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270 Cards in this Set
- Front
- Back
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explain recurrent sclerosiing cholangitis
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-occurs in 20% of recipients who underwent transplant due to cholangitis
-normal waveform, but thickened vessel walls -outpouchings developing due to thickened walls |
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What are the indications for liver transplant?
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-when sugical and medical treatments have failed
-cirrhosis(esp. secondary to chronic, active hepatitis) -fulinant acute hepatitits -inborn errors of metabolism -sclerosis cholangitis -budd-chiari syndrome -unresectable local hepatoma -controversial in mets |
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explain adrenal hemmorrage post LT?
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-observed immediately post op
-due to ligation of RRV -hypoechoic nodular structure -fluid in RT suprarenal region |
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assessory hemiazygos vein
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-ant to vert column and lt ML
-begins at 4-5th intercostal space, and descends to end in the hemiazygos vein -terminates by joining the azygos vein at level of 8th vertebra and drains let side of thoracic wall. -receives blood from 4-8 post intercostal veins, left bronchial and mediastinal veins |
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what is the clinical presentation of HA thrombosis?
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-Delayed blilary leak
-fulminent hepatic failure -intermittent episodes of sepsis |
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what are some contraindications for liver transplant?
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-compensated cirrhosis without complications
-extrahepatic malignancy -cholangiocarcinoma -active untreated sepsis -cardiopulmonary disease -active alcoholism |
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what is the normal flow in hepatic veins?
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-phasic, pulsitile(due to RA pulsations)
-Increase=expiration; decrease=inspiration -hepatofugal -velocity=90-190m/sec |
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What is normal flow in the HA , PV, and HV post trasplant?
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HA:
-rapid systolic upstroke -AT <100msec -continuous flow throughout diastole RI=0.5-0.7 PV: continuous hepatopedal -mild velocity respiratory variations HV: -phasic -physiologic changes in blood flow during the cardiac cycle |
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What may thrombus affecting portal vein thrombosis be caused by?
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Thrombosis may be caused by:
Sluggish flow in patients with cirrhosis. Hypercoagulable states, Surgery Intraperitoneal inflammatory processes causing portal phlebitis (associated with pancreatitis or appendicitis) Tumor invasion usually occurs |
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Explain the complications with liver transplant that involve infection?
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Ocurrs when patients are predisposed to long operative procedures, and/or immunosuppresive therapy.
-cliical appearance of sepsis is altered, so all collections should be assessed thouroughly. |
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what are the u/s fingins of morphologic heptaic vein occlusion?
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(due to changes in the liver)
-acute=hypoechoic and enlarged liver -chronic=shrunken and echogenic fibrotic liver |
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HOw is portal hypertension categorized, in each category, what are the causes of portal hypertension?
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Prehepatic:
-thrombosed PV or splenic vein -extrinsic compression of PV Intrahepatic: -cirrhosis -heptatic fibrosis -lymphoma Post hepatic: -IVC obstruction -HV obstruction |
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what are the normal post TIPS doppler findings?
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-high velocity turbulet flow throughout stent
-heptatofugal flow in intrahepatic PV -increased HA PSV -increased velocity in MPV -increased HA velocities |
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what are the risk factors for HA thrombosis post LT?
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-complex cascular reconstruction
-rejection -severe stenosis -increased cold ischemia time of donor liver -ABO blood type incompatalbity |
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doppler flow w/ hepatic artery stenosis
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-tardus parvus
-RI<0.5 -AT>80msec -PSV-200-300cm/sec |
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what are secondary changes as a result of hepatic vein occlusion?
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-ascites
-pleural effusion -GB edema -splenomegaly -portosystomic shunts |
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cavernous transformation
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-indicates chronic thrombosis
-tangle of vessels in porta hepatis(1-3 wis post trauma) |
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what are some possible intrahepatic solid masses that can be seen post LT?
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-benign solitary hepatic lesions
-infarcts -abscesses -hematomas -recurrent HCC -post transplant lymphoproliverative diseases |
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When is a coronary vein considered dialated? what other features does it have?
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A dilated coronary vein may be seen traveling in a cephalad direction slightly to the right of the portal confluence. NOTE: Visualization of this vein is normal in many patients and is only diagnostic as a collateral if the diameter exceeds 7mm. Hepatofugal flow also indicates abnormal portosystemic pressure gradient.
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what are possible biliary tract complications post liver transplant
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-leaks
-stricture -intraluminal sludge or stones -dysfunction of sphincter of oddi -recurrent disease(sclerosis cholangitis) |
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Explain stenosis o thrombus of the PV post LT?Risk factors and clinical presentation
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-uncommon(1-13%)
RISK FACTORS: -faulty surgery -hypercoagulable states -previous PV surgery Clinically: -hepatic failure -signs of portal hypertension |
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what are the doppler findings of celiac artery stenosis?
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-may be normal
-tardus parvus waveform in transplanted HA -high velocity jet across celiac stenosis |
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azygos sytem
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-collects blood from the thorax and abd wall
-may serve as a bypass for the IVC to drain blood from the lower body -small veins link the azygos w/ the ivc -large veins draining lower limbs and abd. conduct blood into the azygos, so if the IVC or PV become obstructed, the azygos can retrum blood from the lower body to the SVC |
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what percent of TIPS shunts occlude within the 1st year?
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25-66%
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explain HA stenosis
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11% of trx patients
-usually @ anastamosis -present with biliary ischemia, and abnormal LFT's |
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explain vascular complications of liver transplant?
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-vascular thrombosis affecting the HA, PV, or IVC and AO
-arterial thrombosis may occur in 3-10% of recipients -may cause infartion, ishemia, biliary stricture, and necrosis -arterial thrombosis is life thretening requiring immediate transplant -IVC thrombosis is usually related to budd-chiari syndrome |
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Why does budd-chiari syndrome form?
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A Budd-Chiari-like syndrome may develop with excessive right atrial pressure as seen with severe CHF or pericardial tamponade.
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Explain billiary strictures
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-diff. to diagnose(due to poor patient nerve sensistivity)
-patients present as assymtomatic and jaundice -based on location (anastomotic strictures, or intrahepatic strictures) |
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Explain biliary complicatoins with liver transplant?
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-15% of people are affected
-includes biliar stricture and leaking -If stricture is detected, HA stenosis or occlusion should be suspected |
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What are the u/s findings of chronic HV occlusion?
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-collaterals
-portal vein abnormalities -thrombotic scarring |
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what are the risk factors for HA stenosis?
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-Faulty surgical technique
-clamp injury -rejection -intimal trauma due to perfusion catheters |
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what factors might cause a false postive for HA thrombosis?
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-severe Hepatic edema
-systemic hypotension -high-grade hepatic artery stenosis -poor vis of porta Hepatis |
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What is removed with liver transplants?
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-Cholecystectomy
-right hepadectom(seg 5-8) -RHV -IVC and SVC dissconnected -CBD disconnected. |
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when is the presence of collateral channels diagnositic of PHTN?
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always unless there is venous thrombous
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always unless there is venous thrombous
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-focal area of narrowing in intrahepatic CBD
-segmental dialation of intrahepatic bile ducts -with no evidence of obstructin mass -echogenic intraluminal material=ominous |
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Leiriche syndrome
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occlusion of AO from SMA to illiacs. COllateraliatio usually occurs through epigastric arteries
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explan the U/S appearance of reccurrent sclerosing cholangitis
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-diffuse mural thickening of intrahepatic/CBD
-diverticulum-like outpouchings of CBD |
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How should one go about imaging portosystemic shunts on U/S?
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-begin w/ splenic vein(If flow is toward the spleen (reversed), then splenogastric or
spenorenal channels likely exist.) -MPV, RPV, LPV(flow reversal or to/fro flow indicates collaterals -Umbilical vein(?patent in the falciform ligament when following left portal vein appears as hepatofugal) -coronary vein(?dialated to the right of portal confluence. Abn. is hepatofugal flow, and/or >7mm) -assess GB wall and bed(look for varices) -examine posterior lt lober in sag(looking for gastric or gastroeploic collaterals) -check gastroesophageal juction(for collaterals) -assess splenic hilum and upper and lower poles(collaterals) |
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Explain portal systemic shunts via the LT gastric vein?
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-aka coronary vein
-retrograde flow in 80-90% of PH -may cause esophageal varices -gastric varices(stomoch, under lt lobe of liver, and near spleen) |
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What are the symptoms of portal hypertension?
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-GI bleeding
-ascites -hepatomegaly -splenomegaly -esophageal varices -jaundice |
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explain the cause and significance of celiac artery stenosis?
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cause:
-atheromatous disease -impingement by medial arcate ligament of diaphragm Signifance=can decrease arterial flow to allograft |
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what are the clinical and U/S findings of membranous obstruction of the IVC?
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Presenting signs and symptoms
Bilateral lower extremity swelling Signs of hepatic vein obstruction Ultrasound findings: Obstructing membrane visible at diaphragm Reversed blood flow in IVC Markedly dilated IVC Dilated obstructed hepatic veins with sluggish continuous flow Intrahepaticvenous collateralization Ul |
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hepatic vein variations
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-middle and lt hepatic veins form a trunk before entering IVC(96%)
-Inf. RHV-10% -RVH missing -douplicated LHV |
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Explain intrahepatic strictures
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-occur prox to anastomosis
-may be unifocal or multifocal -most result from ischemia(HA occlusion) -the reconstructed HA is the only blood supply to CBD and Intrahepatic ducts |
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What things are associated with biliar strictures?
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-HA stenoss or occlusion
-Pretransplant primary sclerosis cholangitis -choledochojejunostomy -cholangiits ant liver biopsy -young age |
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Explain hepatic artery thrombosis
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-most significant vascular complication(due to blood supply)
-up to 12% of post LT |
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what are the major portosystemic collateral routes?
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-umbilical vein
-gastroesophageal -gastropepiploic(rt and lt) -splenorenal -pancreaticduodenial -hemorrhoidal |
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Explain the U/S findings of HA thrombosis
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-increased PSV>200-300cm/sec
-tardus parvus waveform -RI<0.5 -AT>100ms |
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congestive index
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-a quantification of portal hypertension
-=PV area/mean PV flow velocity normal=<0.7 |
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common hepatic artery
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-rt branch of celiac axis
-courses adj to portal vein to porta hepatis -gives rise to gastroduodenal artery, then travels superior to porta hepatic where right gastric artery branches off -turns into hepatic artery proper |
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Explain hepatic artery flow
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-low resistance
-large continuous forward flow in diastole -PSV-60-140cm/sec -RI=0.8 -Absent focal increase in velocity |
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what is hemostasis?
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-stabilization of vasculature of new liver
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what are some complications that could happen with liver transplant?
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1. Rejection:
2. Vascular complications: 3. infection 4. biliary complications 5. neoplasia |
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describe the flow pattern of the HV normall, and abnormally?
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normal:
-phasic, pusitile(increase w/ expiration, and decrease w/ inspiration) -hepatofugal flow -velocity=90-190cm/s Abnormal: -non-pulsitile -to/fro flow or hepatopedal -stenotic velocity>200cm/s |
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what is the normal flow of the pV?
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-heptatopedal
-continuous and phasic -average=15cm/sec -increased flow w/ expiration -70-100% from quiet to deep respiration -mean velocity=15-88cm/s -diameter in quiet respiration=13mm -measured where the PV crosses anterior to the IVC |
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what is the normal flow in the hepatic artery? w/ stenosis, and thrombosis?
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normal:
-low resistance -large continuous flow in diastole -PSV-60-140 -RT=0.8 Stenosis: -tardus parvus -RI<0.5 -AT>80 -PSV 200-300cm/sec Thrombosis(partial) -tardus parvus -RI<0.5 -AT>100ms -PSV=200-300cm/sec |
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what is flow like in the HA w/ a transplant normally?
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-AT<100ms
-RT=0.5-0.7 |
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what is normal and stenotic flow of a tips shunt?
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normal:
-stent mean-135-200cm/se -main PV=37-47cm/sec -HA=increased from 80 preshunt to 131cm/sec post W/stenosis: -most commonly seen in HV branch -<50cm/sec=concern\ <30cm/sec=failure |
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congestive index
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has to do w/ portal hypertension:
(PV area(cm2)/(mean PV velocity(cm/sec)) -normal =<0.7 |
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what is the renal artery flow normally, and w/ stenosis?
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NORMAL:
-low resistance -high velocity(74-127cm/sec) -high diastolic flow(EDV-30-35) -RAR<3.3 -AT<70ms Stenosis: -50-60% diameter reduction PSV>180-200cm/sec -RAR>3.3-3.5 AT>70 -intrarenal damping |
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what are the RI's like w/ normal and abnormal renal transplant? what is normal flow in a renal transplant?
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RI-0.6-0.8=normal
RI0.8-0.9=equivical RI >0.9=abnormal(increased intraparenchymal resistance) PSV<200cm/sec |
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what is the flow like in a transplant kidney w/ RA stenosis?
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-PSV>200cm/sec
-post stenotic turbulence -prolonged AT w/ intralobar and segmental arteries -intrarenal arteries are normal |
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what is the normal flow in the celiac artery? w/ stenosis?
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Normal:
-low resistance -high EDV(31-35cm/sec) -PSV=98-105cm/sec -mean-102-105cm/sec -higher resitant @ the origin |
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what is the flow like in the CA w/ >70% stenosis?
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>200cm/sec and post stenotic turbulence
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what is normal flow w/ a fasting SMA? post prandial?
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fasting:
-high resistance -low diastolic(11-16cm/s) -PSV=97-142cm/s -tubulent near origin -sharp systolic peaks Post prandial: -low resistance -incresed PSV and EDV -broad systolic peaks -continuous in diastole -PSV increased by 40% -mean flow increased by 164% |
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what is the normal flow of the iMA?
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-PSV-98-190cm/s
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what is flow like w/ mesenteric stenosis?
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>70% only significant if it involves 2 or more mesenteric vessels
->3 for messenteric-aortic ratio |
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mesenteric aortic ratio
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normal=1
equivical=1-3 abnormal>3 |
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name the resistive indices for HA, HA stenosis or thrombosis, HA transplant, and the variations w/ renal transplant
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HA=0.8
HA stenosis or thrombosis=<0.5 HA transplant=0.5-0.7 Renal transplant: normal-0.6-0.8 equivical=0.8-0.9 >0.9=abnormal |
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what are the AT fir HA stenosis, HA thrombosis, HA transplant, RA, RA stenosis, RA transplant stenosis
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HA stenosis=>80ms
HA thrombosis=>100ms HA transplant=>100ms RA=<70ms RA stenosis>70ms RA transplant stenosis=prolonged |
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what is the suggested criteria for carotid stent stenosis?
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50-75%=PSV>150-200cm/sec; ICA/CCA ratio 2:4
70-80% stenosis: PSV>300cm/sec; ICA/CCA ratio >4 >80% stenosis: PSV 320-340cm/sec EDV 120-140cm/sec |
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what are the complicatios for bypass grafts in the first 30 days, 1-6 months, 6-24 months, and >24 months
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-<30 days: Technical, hypercoagulable states, inadequate flow
-1-6mo: residual lesion -6-24mo: myointimal hyperplasia ->24 months: progression of atherosclerosis |
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what is the diagnostic criteria for graft stenosis?
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1-19%-minimal disease w/ minor changes within lumen walls; PSV <150cm/sec, VR<2
20-50% diam reduction: PSV <150cm/sec; EDV<100cm/sec; VR 1.5-2.5; mod spectral broadening 50-74%= PSV>140cm/sec; EDV<100cm/sec; VR 2.5-3.5cm/sec; spectral broadening throughout cardiac cycle w/ turbulence 75-99%=PSV>300cm/sec; EDV>100cm/sec; VR >3.5; ABI >0.15 change from serial exam; spectral broadening throughout cardiac cycle and turbulence Total occlusion: total lack of flow within graft |
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What are the rescan times for bypass graft surveillance with no stenosis, low grade stenosis, mod stenosis, and severe?
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no stenosis=rescan as clinically indicated by the physician
Low grade stenosis: 6 wks Mod stenosis: 4 wks Severe=revision |
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what is the criteria for failing iliac system(threshold for graft revision)
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-ABI or to pressure decrease by >0.15 from previous
-abnormal CFA doppler wavefom -PSV>300cm/sec; EDV 20cm/sec -VR>2 -Overall velocity(<40-45cm/sec) |
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When should infrainguinal bypass, peripheral PTA, carotid endartectomy, and patients who have had procedures w/ residual stenosis be brought back for their first follow up visit?
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Infrainguinal bypass=2-3 wks
Peripheral PTA=1 month Carotid Endartectomy=2-3 months Procedures w/ residual lesions=as early as needed |
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Dialysis graft flow volumes?
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-Normal range=300-1000ml/min
-poor dialysis(pending failure)=<250ml/min -possible CHF=>1200ml/min(still falls within normal range, but patients just have CHF |
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what is the normal spectral doppler for renal dialysis grafts and fistulas?
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PSV=100-400
EDV=60-200cm/sec High flow, Low resisitance, disorganized w/ spectral broadening |
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What is the dialysis graft stenosis criteria according to diagle?
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Mild=Velocity increase, but<50% increase in velocity compared to the preceding segment
MOderate=velocity increase btw 50-99% of preceding segment Severe=velocity increase>100% of preceding segment w/ a 50% velocity drop distally; PSV>300cm/sec |
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What is the stenosis criteria for dialysis fistulas?
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PSV>250-400cm/sec=at least >50% stenosis
Ratio>3:1 PSV@ stenotic site compared to 2cm cranially |
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when there is significant distal ICA stenosis, what will the happen with supraorbital PPG when the temporal artery is compressed? Infraorbital or facial artery?
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-Temporal artery=decreased pulse amplitude(>33% or precompression amplitude)
-Infraorbital or facial artery compression=decreased pulse amplitude>15% compared to precompression amplitude |
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what is normal OPG-Gee?
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-<5mmHg pressure diff btw eyes
-eye /brachial index>1 |
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Both the deep superior epigastric artery and the deep inferior epigastric artery branch off a different artery. Name the arteries.
Both of these arteries contribute blood to what muscle? |
-The superior epigastric artery is a terminal branch of the internal mammary artery.
-It branches smaller, anastomosing with branches of the deep inferior epigastric artery which arises off the external iliac artery. -This anastomatic region is known as the “watershed area”. -Both of these arteries, including their perforators, contribute to the blood supply of the rectus abdominus muscle, a long strap muscle, vertically oriented, lying one to either side of midline. |
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Describe “blue toe syndrome” and what causes it.
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-when embolic material moves distally until it becomes lodged in a small caliber vessel such as a digital artery.
-The resulting lack of flow causes cyanosis (bluish discoloration related to the presence of deoxygenated hemoglobin in the blood). -can be a reversible condition. This syndrome may be caused by any of the following: aneurysmal disease arteritis (inflammation of the artery wall that can lead to thrombosis) ulcerated and/or atherosclerotic lesions some angiographic procedures |
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Name at least 3 veins that are preoperatively mapped for use as a bypass graft.
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-greater saphenous vein (GSV),
-cephalic vein, -basilic vein -lesser saphenous vein. |
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What is the name of this commonly used dialysis access at the wrist?
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Brescia-Cimino.(radial artery anastamosed to cephalic vein)
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Describe two complications that can occur with placement of a hemodialysis access graft.
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1. Increased venous return to the heart, resulting in congestive heart failure (CHF). The closer to the heart the access graft is (e.g. arm), the higher the likelihood is of this happening.
2. “steal syndrome”. With the “dialysis access” in the forearm (e.g. Brescia-Cimino), a “steal syndrome” would cause pain on exertion, and pallor and coolness of the hand due to its distal proximity to the shunt. |
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what questions should we, as sonographers, ask ourselves when performing serial scans on a bypass graft patient?
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-Has flow in any graft segment decreased by at least 30 cm/sec?
-Has the Doppler signal quality changed from triphasic to biphasic? -Has the ABI decreased by more than 0.15? -Has the Doppler PSV decreased to < 45 cm/sec in the smallest diameter |
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What is OPG-G?
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(OPG-Gee)
-measures intraocular pressure -Since ophthalmic artery pressure reflects pressure in the distal internal carotid artery (ICA), the measurement of ophthalmic artery pressure can help detect a hemodynamically significant lesion in the ICA. -However, occlusive disease of the distal ICA is rare. Therefore abnormal findings are usually consistent with a hemodynamically significant lesion at the proximal ICA i.e. at the take off of the vessel. |
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what are not contraidications of OPG-G testing that some people might have thought would be?
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myopia(nearsitedness) and conjuntivitis are not contraidications.
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A patient presents to your diagnostic facility to evaluate an asymptomatic right carotid bruit. The carotid duplex examination documents a complete occlusion of the left internal carotid artery. Name three collateral pathways that could be providing blood flow to the left hemisphere preventing a neurological deficit.
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-Cross-over collateralization:
-External-to-internal collateralization: -Posterior-to-anterior collateralization: |
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explain cross-over collaterals
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-Cross-over collateralization: Antegrade flow is evident in the anterior cerebral artery. Flow is crossing over from the contralateral anterior cerebral artery via a patent anterior communicating artery.
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Explain posterior-anterior collateralization
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-Increased flow velocitie in the posterior cerebral artery.
-Anterior circulation is via the posterior communicating arteries. |
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what are the contraindications for using the radial artery for CABG?
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-ishemic digits
-raynaud's syndrome -ipsilateral athero-occlusive disease in the arm -sclerotic, atresic or occluded radial artery -incomplete palmar arch |
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explain the course of the basilic vein
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-ulnar side of the wrist
-travels medially to join the brachial vein at the mid to upper 1/3 of the arm |
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what are the baseline PVR parameters for the resting digit study?
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-digital BP should be within 20mmHg of the braqchial pressure
-digital/brachial ratio>0.8 -waveform should demonstrate upstroke time<0.2 seconds, and dicrotic notch |
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Explain artery grafts?
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-often the graft of choice over veins due to the ability to anastomose the artery to the native vessels and better longevity
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what arteries may be used for artery grafting?
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-mammary or radial artery
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explain how to mark the GSV a vein?
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-marks should be made every 2 cm
-vein should be centered in the middle of the u/s screen -mark skin w/ straw, use a washcloth to wipe off gel, then mark the skin w/ an undelible marker -dry the leg completely when finished, and connect the dots -if a section is<2mm, it should be represented by a dotted line -if a dual system is seen, the larger one should be a solid line, and the smaller one should be a dotted line |
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what are the indications for vein mapping?
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-decreased amount of dissection
-decreased wound complications -increased accuracy -less expensive than venography |
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explain the procedure for radial artery duplex imaginge?
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-identify orign at the brachial artery
-measure diameter -scan the course of the artery and measure distally -average=2.8-men; 2.4mm=women -make sure diameter is at least 2mm, but preferably >2.5-3mm -not the course and any deviations from normal |
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explain how to mark valves and tributaries?
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-best identified in the trx plane
-valve sites may be identified by observing the dialation of the vein at the sinus(don't always see leaflets) -tributaries should be marked according to their direction -perforators are identified by their communication w/ the deep venous system |
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Explain the course of the cephalic vein?
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-begins along radial aspect of the hand
-communicates with basilic vein in the antecubital fossa via the medial cubital vein -asc. laterall and empties into the axillary vein |
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where is the cephalic vein measured?
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-upper arm
-mid arm -antecubital fossa -forarm -wrist -anatomic variations exist(most common is absent or atretic vein in upper or lower arm) |
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What does pyelopnephritis look like sonographically?
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-lumen of collecting system becomes anechoic.
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what are possible causes of long term hydro post renal transplant?
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-scarring at UVJ
-obstructing debis within ureter -ureteral cmpression by extrinsic fluid collections -disorders that delay emptyng of the bladder -vesicoureteral reflux |
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where will renal artery stensosis occur in renal transplants?
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-anastomosis(usually end to end)
-distal donor artery(usually end to end) -recipient artery(equally in both types |
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What is evident w/ doppler U/S w/ acute, sever rection of a renal allogragt?
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-increased flow resistance
-decreased or absent flow in diastole -flow eversal in diastol -RI>0.7 =PI>1.8 |
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EXPLAIN VENOUS THROMBOSIS WITH RENAL ALLOPGRAFTS? What are the U/S findings?
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VENOUSTHROMBOSIS
-Slightly more common than arterial thrombosis -Occurs in up to 4% of transplants -Associated with: -Acute pain -Swelling of allograft -Abrupt cessation of renal function (3-8 postop day) U/S findings: VENOUSTHROMBOSIS Slightly more common than arterial thrombosis -Occurs in up to 4% of transplants -Associated with: -Acute pain -Swelling of allograft -Abrupt cessation of renal function (3-8 postop day) |
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What would acute renal thrombosis appear like sonographically?
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-enlarged kny w/ loss of corticomedullary differentiation, and hypoechoic cortex
-hyperechoic cortex w/ preservation of corticomedullary differetiation -mottled, heterogenous echotexture, -or, echogenic streakes seen throughout kny. |
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Explain what happens during transplant of a living liver donor?
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-55% of liver is taken from donor and it should regenerate within 4-6 wis.
-when a liver is placed in a recipient, they connect the hepatic vasculature 1st, then make sure the liver is being profused, then connect billiary. |
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What is it important to look for with polar accessory renal arteries?
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look for compression of the ureters because they can cause this.
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What is the flow like in normal extraparenchymal transplant arteries? What would cause a change?
|
normally low resisitance
-an increase in resistance would be due to: -acute rejection -renal vein thrombisis -infection -tubular necrosis |
|
|
when might false positives occur with renal artery occlusion?False negative
|
-poor vis
-small kny for other reasons FALSE NEGATIVE: -adequate collaterals |
|
|
what is the sonographic appearance of renal vein thrombosis(acute, and chronic)
|
ACUTE:
-Renal enlargement -Hypoechoic cortex with decreased corticomedulllary differentiation -Hyperechoic cortex with preservation of corticomedullary differentiation -Mottled heterogeneity accompanied by loss of normal intrarenal architecture -Echogenic streaks CHRONIC: -Recanalization may occur -May return to normal sonographic appearance -May undergo fibrosis -Increased echogenicity -Decrease in size |
|
|
lymphocele post op
|
-pain or asymptomatic
-1-2 months post op -interupted lymphatics from surgery ML btw allograph lower pole, and bladder -loculated w/ thin septae |
|
|
what are some causes of renal artery thrombosis?
|
-acute and hyperacute rejection
-iatrogenic -hypotension -vascular kinking -cyclosporine -end-to end anastomosis -hypercoagulable states -atherosclerotic emboli |
|
|
What patients are appropriate candidates for renal artery assessment of stenosis?
|
-young patients w/ severe hypertension
-patiens w/ rapidly worsening hypertension(malignant) -uncoltrollable hypertension -pt. w/ renal insufficiency and hypertension -pt .w/ renal insufficiency and discrepant kny size |
|
|
what may happen as a result of stenosis and/ or occlusion of the renal artery?
|
-may cause hypertension because the renin-angiotension system is triggered
-may cause parynchmal damage to kidney |
|
|
What may renal artery stenosis be caused by? what may it cause?
|
-atherosclerosis or fibromuscular hyperplasiam
-may cause hypertension |
|
|
causes of renal vein thrombosis
|
-underlying kny anomolies
-hydration status -coagulation status -tumors of the kny -adrenal tumors- -membranous glomerulonephritis -extrinsic compression from tumors -trauma -pancreatitis -retroperitoneal fibrosis |
|
|
what is a secondary sign of renal vein thrombosis?
|
-absent or reversed end-diastolic flow in the renal arteries of the parynchma of the native kny.
|
|
|
expalin the clinical and doppler findings in an occluded renal artery or vein?
|
CLINICAL:
-arterial: <1% -immediately post op -may be caused by rejection -Venous: <1% -occurs immed. post op -kny enlarged, congested DOPPLER: -absent arterial and venous flow -absent renal vein flow -distended vein -intraluminal echos -diastolic flow reversal in renal arter |
|
|
explain acute tubular nechrosis?
|
Results from donor organ ischemia either prior to vascular anastomosis or secondary to perioperative hypotension
-Most common in early postoperative period -Major cause of delayed graft function -Occurs in most cadaveric grafts -Observed infrequently in living related renal transplants due to short cold ischemic time of donor kidney (LAST SLIDE=56) |
|
|
what is the normal orientation of the kidney in a renal allograft?
|
Renal pelvis ant
Renal vein post renal artery btw vein and pelvis -the long axis of the kidney is usually parallel to the incision site. |
|
|
how often does IVC tumore invasion occur w/ RCC/
|
-5-10%
|
|
|
What happens with fibromuscular dysplasia and renal artery stenosis?
|
-stenosis may occur anytim along the artery
-fibromuscular dysplasia patients are particualarly challenging for detection of stenosis |
|
|
Arterial fibrodysplasia
|
-non-atherosclerotic, non-inflammatory vascular occlusive and aneurysmal disease
-arteries involved: renal, cerebral, axillary, subclavian, brachial, celiac, SMA, IMA and others Ocuurs <0,5%, but is the second most common cause of sergicall correctable hypertsion(to atherosclerosis) -occurs in women40-50 |
|
|
what are some conclusive findings for renal vein thrombosis?
|
-enlarged renal vein
-loss of doppler signal -low flow seen, and loss of phasicity -collaterals identified -venous intrarenal flow present, but losss of phasisicity and lower velocities |
|
|
where does renal artery stenosis most frequently occur?
|
-at the hilar region
-if there is duplication, or accessory arteres, sensitivity is dramatically decreased -if an accessory or duplicated artery is missed w/ stenosis, angio may not be done to correct the problem of hypertension |
|
|
how does intrarenal evaluation of a waveform give information about a renal artery stenosis?
|
-If the accel time is >70ms=significant stenosis
|
|
|
with renal transplants, how is the donor artery anastamosed?
|
-to external iliac artery(end-to side), or internal iliac artery(end to side), internal iliac artery(end to end)
-renal vein connected to EIV(end to side) |
|
|
explain the clinical and doppler findings with A-V fistula post renal op
|
CLINICAL:
-may be due to biopsy trauma -connection btw art. and vein -may be asymptomatic or hypertensive DOPPLER: -disturbed flow that stands out in renal parynchma -high velocity flow within artery -color bruit seen in parynchma next to fistula |
|
|
what is the u/s protoco for allograft images?
|
Done 2 days post op, and 1-2 wks, and 3 months post-op.
IMAGES; Sag and trx measurements -images of stent if there is one -note hydro -note size, type, and location of fluid collections around allograft, and at surgical site DOPPLER(spectral and color to include PSV, PI, and RI): -arcuate arteries of Upper, mid, and lower poles -main renal artery -main renal vein -anastomotic site |
|
|
what are the pitfalls with renal vein thrombosis?
|
-false positive w/ slow flow within renal vein
-false negative w/ anechoic thrombus -false negative if flo is seen as a result of collaterals |
|
|
What ways could the renal artery be attached with a RT?
|
-end to side(most common)(end of donor attached to side of external iliac artery)
-end to end -patche onto the iliac artery w/ a peice of dor aorta(carrell's patch) |
|
|
explain collecting system obstruction post renal transplant
|
Unusual in renal transplants
Occurs in less than 5% patients -Allograft is denervated = collecting system dilates without clinical signs of pain or discomfort -Often made as an incidental finding on routine screening Ureteric-vesical anastomotic site -Most frequent location -Stricture or intraluminal lesion -Extrinsic compression of ureter |
|
|
name some non-vascular renal diseases?
|
-Urinary tract infection
-Glomerulosclerosis -Acute tubular necrosis -Pyelonephritis |
|
|
How are large AV fistulas treated? What is the result of them if not treated?
|
-treated by percutaneous embolization
-cause a decrease in perfusion to kidney -symptoms are persistent hematuria, and high output cardiac failure |
|
|
draw the waveforms for the normal RA, RA w/ transplant, RA stenosis of the transplanted kidney
|
refer to notebook
|
|
|
what are the clinical findings of arterial stenosis post RT?
|
CLINICAL:
-10% of allograph pt. -within 3 yrs -hypertension -may be due to rejection -may result from intimal hyperplasia |
|
|
what are some intrinsic or extrinsic lesions that occur post renal transplant? They can obstruct either a component of the calycealsystem or the transplanted ureter
|
-Include:
-Postrenalcollecting system obstruction -Arteriovenousmalformations -Pseudoaneuryms -Fluid Collections |
|
|
what is the cause and of arterial fibrodysplasia?
|
-largely unknown, but may be related to arteritis
-developmental renal artery stenosis is a form of fibrodysplasia that occurs in the pediactric population by 40% in those w/ renovasculature hypertension |
|
|
what are good questions to ask patients who are being checked prior or post RT?
|
-high BP
-history of headaches, dizziness, nosebleeds, or flushed face and tiredness -blood in urine -problems urinating -back pain or abd. pain |
|
|
Explain stenosis in intrarenal doppler assessment?
|
-causes a tardus-parvus waveform within the kidney
-increase accel time(>70ms=severe stenosis), low systolic velocity and increased diastolic flow -increase in diastole is due to dialation of arterioles in response to ischemic tissues -intrarenal flow changes=70% or more stenosis of the renal artery |
|
|
what arteries, and where on the arteries should be interrogated(for a renal study)?(7)
|
-Right renal artery=close to Ao, Mid, and and at hilum
-segmental=LP, MP, UP -interlobar=doppler (total seven doppler sites) |
|
|
what are the parameters for renal artery stenosis of the transplanted kidney
|
-PSV>200cm/s
-poststenotic turbulence -prologed AT w/ intralobular and segmental arteries -intrarenal arteries are Normal |
|
|
what are the limitations and advantages of a renal allograft?
|
LIMITATIONS;
-Continuing shortage of suitable donor kidneys -Average life expectancy for cadaveric allograft is 7 –10 years -Live donor allograft is 15 –20 yrs ADVANTAGES: -cost outweighs living w/ chronic renal failure |
|
|
What naturally occurs w/ renal vein thrombosis?
|
-induces ischemci parynchmal damage, and acute renal failure
-recanalaization and collaterals can occur,and if adequate, kny can return to normal apparance -if kny was severely damaged, it would become echogenic and small |
|
|
what may a patial renal artery thrombosis show?
|
-reversed or decreased diastolic arterial flow
|
|
|
post renal stent surgery, what should you(as a sonographer)look for?
|
LOOK FOR:
-renal artery dissection -distal embolization to kidney -thrombosis -incomplete deployment of stent |
|
|
what is the appearance of arterial fibrodysplasia?
|
-circumfrenetial, and smooth occuring most in the main renal artery
-may be solitary focal stenosis or a series of stenosis with aneurysmal outcpouchings(string of pearls) -most stenosis occur midvessel, but may occur distal and rarely in to branch vessels |
|
|
Enlargement of the renal vein
|
-could be due to splenorenal or gastrorenal shunting found in portal hypertension
-ther causes could be tumor invovement or AV fistula |
|
|
what is the treatment for renal artery stenosis?
|
-surgery by placeing bypass graft around stenotic segment
-segment dialated by ballon angioplasty -remove plaque and widen artery with vein patch -renal arty stenting |
|
|
what is the criteria for renal artery stenosis?
|
normal=74-127cm/sec
50-60% diam reduction-PSV=180-200cm/sec -renal/AO ratio>3.3-3.5 AT >100-120ms (some books say>70ms) >60% diam reduction=dampening as the AT>0.07 sec. AT>0.1-0.12sec=significant stenosis |
|
|
what is the result of SMA syndrome?
|
Results in chronic, intermittent, or acute complete or partial bowel obstruction
Difficult to diagnose Requires Radiographic Studies: Upper GI CT Ultrasound |
|
|
what is the treatment for chronic and acute mesenteric ishemia/
|
Goal: re-open stenotic artery
Chronic Trans-aortic endarterectomy Bypass surgery Angioplasty and stenting Acute Emergency procedure Thrombolytic agents to dissolve clot Surgery if bowel damage irreversible |
|
|
SMA compression syndrome
|
-aka arteriomesenteric duodenal compression syndrome, or wilkie's syndrome.
-uncommon -compression of trx part of duodenum against the AO by the sma -SMA is usually 45 degrees w/ the AO, and the 3rd part of the duodenum crosses underneath, but when the angle btw the AO, and SMA is <45 it could cause compression of the duodenum -often due to loss of fat btw sma and AO |
|
|
what are the symptoms of chronic messenteric ishemia>
|
Symptoms:
Abdominal cramps / bloating Post prandial pain Weight loss Diarrhea / Constipation Flatulence AKA: “fear of food “syndrome |
|
|
what is the cause, and symptoms of acute messenteric ishemia?
|
Life-threatening emergent condition
Symptoms: Acute sudden onset of abdominal pain Abdominal distention Fever Dehydration Acidosis Cause: Embolic occlusion of one or more of the mesenteric vessels: -arterial embous -arterial thrombosis -non-occulusive pathology |
|
|
what can acute arterial thrombus be due to?
|
Atherosclerosis
Arteritis Ao dissection |
|
|
Explain pancreaticoduodenal collateral supply?
|
-natural collateral that connects the celiac axis to the SMA
-The most important collateral supply. - Supply the bowel when either one or both of the celiac artery or SMA is stenosed or occluded. - Flow moves from the hepatic artery to the gastroduodenal artery and into the SMA via the pancreaticoduodenal arteries. |
|
|
what is normal flow in the celiac artery?
|
-PSV=98-105m/sec
-EDV=32-35cm/sec -mean=102-104cm/sec -low resistance -higher resistant near origin -high EDV -continuous throughout diastole |
|
|
what are some common sites of mesenteric ischemia?
|
-superior and inferior mesenteric artery(watershed)
-inferior mesenteric and hypogastric artery(watershed) |
|
|
CACS
|
celiac axis compression syndrome(aka median arcuarte artery syndrome and dunbar syndrome):
-median arcuate ligament of the diaphragm compresses the celiac axis. -occurs during exhalation |
|
|
explain the mesenteric collateral?
|
-@ splenic flexture
-SMA and IMA share circulation |
|
|
what is flow like in the SMA w/ >70% stenosis?
|
-PSV>275cm/sec
-post stenotic turbulence -EDV-45cm/sec -post stenotic tardus parvus waveform. |
|
|
what are the types of mesenteric ishemia/
|
Arterial
Venous Acute Chronic |
|
|
which vessels are considered messenteric vessels?
|
Celiac axis
Lt. Gastric A. Splenic A. Common Hepatic A. Superior Mesenteric A. (SMA) Inferior Mesenteric A. (IMA) |
|
|
Explain arterial embolus, arterial thrombosis, and non-occlusive pathology in regards to acute mesenteric ishemia?
|
Arterial embolism
Usually dislodged cardiac thrombus SMA most commonly affected Arterial thrombosis Pre-existing atherosclerosis Involves at least 2 of the major splanchnic vessels Non-occlusive pathology Primary mechanism: severe and prolonged intestinal vasoconstriction |
|
|
what are the causes of mesenteric ishemia?
|
-Acute arterial embolus
-Acute arterial thrombosis -Nonocclusive ischemia -Mesenteric venous thrombosis – underlying -hypercoagulable state -Mechanical compression - CACS |
|
|
If both the SMA and celiac axis are severely diseased, what happens?
|
-The IMA provides collateral circulation.
-Blood flows from the IMA through the arch of Riolan to the pancreaticoduodenal arteries. |
|
|
how is the penis profused in the penis?
|
Cavernosal Artery
Bulbourethral Artery Dorsal Artery |
|
|
explain venous drainage of the penis?
|
Small veins from corpora cavernosa:
Perforate tunica albuginea Drain into deep dorsal vein Cruralveins: Base of penis Drain into deep pelvic veins to internal pudendal vein |
|
|
explain the physiology of the penis in a flaccid state?
|
Corporal arterioles are vasoconstricted
Sinus cavity smooth muscles are contracted Pre cavernosalA-V shunting Minimal blood flow into cavernosa |
|
|
explain the physiology of the penis in erectile function?
|
Physiologic process
Begins with increased parasympathetic nervous activity to penis Cavernosal arteries dilate Sinusoids fill with blood –corpora cavernosa expand and stretch Occludes the draining veins Continued parasympathetic activity maintains erection Smooth muscle in cavernosal sinusoids relaxes Sinusoids expand |
|
|
what are some other causes of impotence?
|
Scarring within corpora cavernosa or tunica albuginea
Peyronie’s disease(Calcification of severe scarring in tunica albuginea =plaques) |
|
|
what doppler measurements should be taken of a flaccid penis?
|
-Obtain both sagittaland transverse 2-D images
Measure diameter of cavernosalarteries Record color and spectral Doppler tracings from cavernosalarteries Measure PSV & EDV |
|
|
what medications are given to aid in erection during an exam?
|
-papavarine-30-60mg
-prostaglandin E1=10 micrograms |
|
|
Explain doppler assessment post injection??
|
Measure PSV in each artery
Obtain arterial waveforms at 2-3 minute intervals until peak systolic velocity is above 35 cm/s or has plateaued Measure EDV once peak systolic velocity has plateaued Assess flow in deep dorsal vein |
|
|
what is normal doppler evaluation full tumescence?
|
PSV decline
Absent or reverse end-diastolic flow No flow in deep dorsal vein (with color) |
|
|
What is the doppler criteria for normal when looking for arterial insufficiency? Abnormal
|
NORMAL:
PSV > 30 cm/s EDV < 5 cm/s 75 % increase in artery diameter ABNORMAL: EDV > 6 cm/s = venous leak PSV < 25 cm/s < 75 % increase in artery diameter |
|
|
What are the limitations when doing penile spectral doppler?
|
Patient anxiety
Psychogenic impotence Patients with variants of cavernosal arterial anatomy Duplicated arteries ** If more than one artery seen, conclusions regarding arterial function cannot be drawn if PSV < 30 cm/sec. |
|
|
what is the purpose of doing penile pressures and waveforms?
|
-Determine cause of erectile dysfunction
vascular insufficiency other causes May indicate: pelvic steal arterial vasospasm arterial occlusive disease when combined with exercise. |
|
|
what is the root of the penis?
|
posterior and contains the bulb and crus which is attached to the perineum and is enveloped in muscle.
|
|
|
what(overall) needs to be obtained to do a non-duplex test for impotence?
|
-obtain ankle/brachial indices(to see if there is diffuse atherosclerotic disease)
-obtain penile systolic pressures using doppler, PPG -calculate penile/brachial indices -obtain PVR and PPG waveforms |
|
|
how is a penile systolic pressure test done?
|
-cuff applied to base of penis and connected to a manometer
-locate dorsal artery w/ handheld CW probe -infate cuff to obliterate signal from artery -slowly deflate cuff until doppler signal returns -note penile systolic pressure -repeat test to assure reproducability |
|
|
What are the values for normal, and abnormal penile/brachial indices?
|
normal=0.7-1.0
borderline=0.6-.0.7 abnormal=<0.6 |
|
|
Explain the test for reactive hyperemia of the penis?
|
-record PVR w/ 60mmHg pressure
-inflate cuff to 20mmHg above penile systolic pressure for 5 minutes -re-inflate to 60mmHg and record several PVR's |
|
|
if an erection is maintained for 3 hours post pavavarin, what should be suspecte? What should be done about it?
|
If the patient’s erection is maintained for 3 hours post injection, priapism is suspected and urologist should be consulted to reverse it.
|
|
|
intracavus papavarine
|
-used to Differentiates between vasculogenic and psychogenic erectile dysfunction.
-60mg of diluted papaverine is injected into the corpus cavernosum. -A tourniquet is applied at the base of the penis prior to injection - After two minutes, the patient is asked to stand and the tourniquet is removed. -If the patient develops full erection after 10 min, and if it lasts for more than 30 minutes, the arterial, venous and sinusiodal mechanisms are normal. |
|
|
explain the arterial blood supply to the penis?
|
-internal iliac arteries give rise to the internal pudendal arteries
-internal pudendal artery gives off the urethral artery, the bulbar artery and a perineal branch before it becomes the penile artery -Each penile artery divides into the right and left cavernosal arteries and the right and left dorsal arteries. |
|
|
what do the dorsal arteries supply?
|
supply the skin of the penis and glands.
|
|
|
what does the bulbar artery supply?
|
supplies the urethral bulb and the bulbourethral gland
|
|
|
where do most varicocele's occur? why?
|
This occurs more often on the left side due to the high pressures from the left hemiscrotum draining into the left renal vein. The presence of a varicocele on the right may indicate a mass pressing somewhere on the venous pathway.
|
|
|
why is the PBI not a reliable indicater of vasculogenic impotenct?
|
-continuous-wave probe is blind and may not pick up the dorsal arteries instead of the cavernosal arteries
-The measurements taken while the penis is in a flaccid state differ from the measurements taken while the penis is in an erect state. -If the cuff does not fit the penis properly, errors may occur. |
|
|
what are the major pathways available for transfusions?
|
-circle of willis
-intracrantial to extracranial -smal intraarterial communications |
|
|
What is the technique for supraorbital PPG?
|
-obtain signal from PPG
-optimally adjust pulse amplitude(25-30mmheight and paper speed at 5mm/sec) -compress temporal arteries bilaterally(for 5 beats) -depress foot switch at the same time of compression -compress supraorbital -compress both facial art. -compress ipsilateral and contralateral CCA's(optional) |
|
|
what are the eight branches of the ECA?
|
ascending pharngeal artery
superior thyroidal artery lingual artery posterior aurical artery internal maxillary artery superficial temporal artery transverse facial artery occipital artery |
|
|
What are the side effects that occur with OPG-G testing?
|
-subjunctival edema(redness and tearing-usually disappears within 30 minutes)
-severe redness of the sclera -pt. should not rub eyes for a while |
|
|
when does the waveform for OPG-G return? What does the pressure in the opthalmic artery reflect?
|
when the opthalmic arterial pressure exceeds the intraocular pressure
-the pressure in the opthalmic artery reflects the pressure in the distal ICA |
|
|
name and explain the arteries that the circle of willis is made up of?
|
-Anterior cerebral artery-carries 20-30% of the blood to the brain
-middle cerebral artery-carries 70-80% of blood to the brain -post cerebral artery -basilar artery-formed by vert. arteries and supplies blood to posterior structures -distal ICA -ant. communicating artery -post communicating artery |
|
|
What are the techinical errors that can be made w/ periorbital doppler?
|
-ECA branches vs. opthalmic artery branches
-excessive transducer pressure -inapropriate compression technique |
|
|
why would carotid compression maneuvers be used while administering OPG-G test? What is NB to remember when doing these tests?
|
-to determine info about collateral pathways in the brain.
-never compress both carotid arteries or the bulb -compressing the bulb may disturb the heart rate or rhythm, decrease cerebral perfusion, or cause distal embolization from dislodged plaque -carotid compressions should be released slowly to prevent the sudden return of blood flow |
|
|
what collateral pathways come from the ICA? ECA?
|
ICA- supraorbital, frontal, nasal, and opthalmic
ECA-superficial temporal, facial, infraorbital |
|
|
how is the OPG-G test done?
|
-patient supine
-bilateral brachial pressures taken(if BP<140, 300mmHg may be used; If BP>140mmHg, 500mmHg may be needed to obliterate flow) -local anesthetic applied to eyes -eye cups placed on lateral sclera(white of the eyes) -vacuum applied to cups deforming the shape of the globe, and increasing intraocular pressure -strip chart recordings are made as pressure increases to obliterate arterial flow-patient may experience temporary loss of vision -as vacuum is released, pulse returns when the opthalmic arterial pressure exceeds the introcular pressure -pressure in the opthalmic artery reflects the pressure n the distal ICA |
|
|
Explain how carotid compressions are done with OPG-G testing?
|
-carotid artery is compressed for 3-5 seconds while the OPG maintains an intraocular pressure of 60mmHg
-If pulsations are noted during this, then the carotid artery is compressed for < or equal to 15 seconds while the OPG decreases the intraocular pressure from 110mmHg to the level at which the pulsations reappear. -carotid compressions should be released gradually to prevent the sudden return of blood flow |
|
|
what can cause false negatives with OPG testing?
|
-bilateral carotid artery disease
-stenosis<50% -50-70% stenosis produces variable test results |
|
|
If siginificant stenosis is noted with Supraorbital PPG, what will be seen?
|
-W/ temporal artery compression, theer is attenuation of pulse amplitude by >33%
-w/ infraorbital or facial artery compression, there is reduction or >15% or pre-compression amplitude |
|
|
name the periorbital arteries?
|
frontal-inner canthus1-2cm
supraorbital=middle of the eye=2cm opthalmic=5-6cm |
|
|
What could cause a false negative or false positive with supraorbital PPG?
|
False negatives:
-improper ECA branch compression -ipsilateral ICA and ECA obstruction False positives: -vasoconstriction -anomolous circulation -improper compression of ECA |
|
|
what are the contraindications for OPG-G?
|
-patients w/ glaucoma
-patients w/ allergies to local anesthetics -patients w/ hx of or potential for retial detachment -patients who have had eye surgery within 6 months -patients who have acute or chronic conjunctivitis -patients who cannot hold their eyes open |
|
|
what are the limitations of the OPG-G test?
|
-cannot determine exact location of stenosis
-cannot differnetiate btw rt stenosis and occlusion -non-diagnostic when evaluating well-collateralized lesions or non-hemodynamically significant lesions -not usedful for documentation of the progression of disease |
|
|
what are the frequently seen symtoms of posterior cerebral artery stroke?
|
dyslexia and coma
|
|
|
what are the different types of intracranial to extracranial anastamosis?
|
-connections via the opthalmic and orbital arteries, the meningophophyseal branches, and the carotid-typanic branches
-connections via the occipital branch of the ECA and the atlantic portion of the vertebral artery -ECA's connections across midline -Deep cervical and ascending cevical branches of the subclavian artery to the lower vertebral artery, atlantic portion of the vertebral artery, and the occipital branch of the ECA |
|
|
what compression maneuvers should be done for periorbital doppler?
|
-temporal artery
-both supraorbital arteries -both facial arteries -CCA on ipsilateral side(1-3 heartbeats) -contralateral CCA compression if ipsilateral compression is normal |
|
|
what are the branches of the opthalmic artery? What do they supply
|
-central retial artery-supplies the eye
-suptraorbital artery-courses ant. and sup. till it reaches the globe, then joins the ECA via the superficial temporal artery -frontal artery-exits orbit medially to supply midportion of the forhead; joins ECA via superficial temporal -nasal artery/angular artery -branches off the fronatl artery to supply the nose. courses down lateral border of the nose. Joins ECA via the facial artery |
|
|
explain the anatomy of the ICA?
|
-approx 4mm
-usually posterior and lat to ECA, but 15% of the time its reversed -supplies anterior brain, eyes, forehead, and nose -enters the skull through the carotid canal -the first branch is the opthalmic artery -after this branch, it joins the circle of willis and gives off the anterior choroidal and posterior communicating arteries before it divides into the anterior cerebral artery and middle cerebral artery |
|
|
summerize the finding that would be considered abnormal in regards to periorbital doppler?
|
-reversal of flow in either the frontal or supraorbital arteries
-flow reversal(or decreased flow) with ECA branch compression -failure of flow to diminish with ipsilateral CCA compression -decrease of flow with contralateral CCA compression |
|
|
what are the indications for pre-op assessment?
|
-patients with a history of vein stripping
-previous DVT -previous harvesting or bypass surgery |
|
|
explain arterial grafts
|
-radial or mammary arteries
-reduced incidence of basospasm -improved longevity -mapping proceduce-similar to vein mapping -radial artery study for palmar arch patency |
|
|
what is done to reliably identify failing PTA?
|
-serial clinical evaluations-mesurement of limb pressures
-doppler waveform analysis at 6 month intervls |
|
|
what is the protocol for surveillence of PTA's?
|
-obtain post-op history
-perform a pulse evaluation -measure ABI -color doppler -characterize hamodynamics of graft flow |
|
|
explain how to assess endografts w/ 2D, color and spectral?
|
2D;
-assess entire endograft -assess attachment sites -assess entire residual aneurysm sac Color/Spectral: -identify and confirm endoleaks -identify source of endoleak -limb dysfunction -graft patency -outlfow vessels |
|
|
what is the criteria for a failing iliac system?
|
-ABI or toe pressure decrease>0.15
-development of an abnormal CFA doppler waveform -Hemodynamically failing iliac angioplasty: PSV>300cm/sec VR>2 |
|
|
what are abnormal findings when surveying a carotid post intervention?
|
-flow disturbances(intimal flap or retained plaque)
-stenosis -occlusion -myointimal hyperplasia-delayed complication -malposition of stent -separation of stent from vessel wall |
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what is the threshold for graft revision?
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-PSV>300cm/sec
-VR>3.5 -Low velociy<40-45cm/sec -decreased ABI |
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explain the basic conscept of hemodialysis?
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-Central circulation is accessed-AVF, Graft, and central venous catheter
-blood cleansed by diffusion across a semi-permeable membrane -2 15G needles placed into AVF or graft -more distal(caudal) needle carries blood from the patient to the dialyzer -second, mor proximal needle returns blood to patients circulation |
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explain PTFE straight grafts?
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-distal radial artery to cephalic, median cubital or basilic v. in arch near atecubital fossa
-distal brachial artery to prox basilic or axillary vein |
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explain PTFE loop grafts
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-distal branchial artery to cephalic, median cubital, or basilic veins
-proximal brachial artery to axial vein -lower extremity: SMA to saphenous vein |
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what is the preferred order of access for placement of dialysis grafts?
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-non-dominent forarm
-dominent foram -non-dominent/dominent upper arm basilic vein trasposition fistula -forarm loop graft -upper arm straight graft -upper arm loop graft(axillary artery to axillary vein) |
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venous catheters
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usesd for temporary ccess because grafts and fistulas take awhile to mature
-inserted into vein in neck, chest, or leg near groin -have 2 chambers to allow two-way flow of blood -look for thrombus |
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what are some exam indications for dialysis patients?
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-pre-op assessment
-elevated pressures during dialysis -puncture problems -peri-graft fluid or mass -distal limb ischemia -poor dialysis |
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what are some signs of possible access failure twith dialysis grafts?
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-difficult cannulation, or thrombus aspiration
-elevated venous pressure>200Hg -access recirculation of 12% or greater -unexplained area reduction -shunt collapse |
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what is the pre-operative assessment procedure?
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-evaluat arterial inflow
-evaluate entire venous outflow -assess vessel size -assess palmar patency |
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what is considered a normal exam when evaluating the veins for dialysis?
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-absence of stenosis, or thrombosis
-patent deep veins in upper arm -venous luminal diamter: >2.5mm for fistula >4mm for graft |
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what is ultrasound useful for in post-operative assessment?
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-determining graft maturity
-If AVF maturity in doubt, serves as a triage function -evaluates multiple anastomic features of the AVF |
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what are the complications associated with dialysis access grafts/fistulas?
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-thrombosis/occlusion/stenosis
-infection; mostly synthetic grafts(2puncture sites) -arterial steal-digital ischemia -distal venous hypertension -aneruryms, pseudoaneurysms -elevated rt. side heart pressure due to excessive graft flow |
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how is graft flow volume calculated? what is the formula?
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-Q=graft area x TAV x 60
-Q=area x avg max vel. x 60sec -select clean site midgraft -in trx, obtain lumen diamete r(turn off color to measure diameter) -in longitudinal, expand sample gate to diameter of vessel -obtain several spectral wavefomrs and calculate time average velocity. |
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what should you assess with arterial steel?
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-perfusion distally
-obtain PVR's or PPG -obtain digital pressures -if possible, temorarily occlude fistula while obtaining PVR/PPG waveforms |
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What is the normal flow pattern of grafts and fistulas for dialysis?
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PSV=100-400cm/sec
EDV=60-200cm/sec high flow low resistance disorganized flow w/ spectral broadening due to larger diameter of vessel |
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graft stenosis criteria for dialysis grafts?
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-MIld stenosis: velocity increase, but <50% or preceding segment
-moderate stenosis=50-99%velocity increase from preceding segment -severe stenosis: -velocity increase>100% of preceding segment with a 50% drop distally(>50% diam. reduction) -PSV>300cm/sec |
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what is the stenosis criteria for dialysis fistulas
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-PSV>250cm/sec =>50% stenosis
-velocit may be unreliable due to variations in vein diameter -estimating doppler angle is difficult in fistulas(60 degrees is hard to determine) |
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w/ a radial a. to cephalic vein., what is considered stenosis?
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PSV>4m/sec
Ration>3:1(PSV at stenosis/PSV 2 cm cranial to anastamosis) -for outflow cephalic vein stent ratio of 3:1 |
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explain venous hypertension with dialysis grafts?
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-too much blood in the hand; have to go and ligate vessels
forarm loop graft with venous stenosis -retrograde venous flow -patient w/ hand swelling and venous stasis |
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Graft rain
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-artifact caused by air in the wall of synthetic graft material
-doppler signal may not penetrate graft wall -have to rely on information obtained from inflwo and ouflow vessels |
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what is the most common preoblem w/ dialysis grafts? explain it?
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-venous anastamosis site or outflow bein becomees stenotic and thrombus formes due to increased arterial pressure.
-Stenosis in teh venous side of the graft happens in more than 80% of cases -can produce endothelial damage or intimal hyperplasia |
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explain the primary devices used for angioplasy?
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-balloon tipped catheter
-rotational atherectomy catheter(rotablator) |
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what are the benefits of stents?
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-physically opens channel of diseased arterial segments
-releives symptoms of decreased blood supply -increases quality of life -reduces other complication of the disease |
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what are some peripheral sights where stents may be placed?
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-aorta
-renals -iliacs -femoral-popiteal -carotid |
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explain how carotid stents change the carotid artery?
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-metallic stent change biomechanical properties of the carotid artery(decreases elasticity, and complience)
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explain the aortic endovascular stent graft
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-introduced in the 90's
-follow carefully w/ u/s -alternative to surgical repair of abdominal aortic aneurysm -placed transluminally through small femoral incisions and deployed remotely |
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what are the endograft characteristics of support, design, and configurations?
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Support:
-complete externally supported -supported at attachment or fixation sites Design: -modular design -single body construction Configurations: -bifurcated tube -aorto-uni-illiac configuration |
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what are the categories of endoleaks?
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look at diagram in power point:
I-attachment leak 2-branch leak 3-device related 4-graft porosity 5-site undefined |
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explain type 2 endoleak
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Branch leak:
-flow from aortic branches into aneurysm -IMA, lumbar, internal illiac -other sources linked to branches -get to/fro flow due to increased pressure in the endograft |
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Other than endoleaks, what other complications can occur with aortic endovascular stent grafts?
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-graft limb dysfunction
-intimal tears or dissections -pseudoaneurysm -AV fistulas -Ishemia/Embolization -Graft redundancy -wire cracks/fractures |
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Explain endograft limb dysfunction?
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-most common complication other than endoleaks
-twisting or kinking -stenosis/crimping -incomplete deployment -thrombosis/occlusion -migration |
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what are the acoustic characteristics of renal stents?
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-echogenic-if pure metal=well seen
-not always well visualized -image perpendicular to the arterial wall |
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what are the flow patterns of renal arteries post stenting?
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-flow disturbances at orifice(may indicate stent protrudes into AO too far)
-minimal flow disturbances in prox. stented segment(reduced wall complience) -elevated velocities at distal end of stent(diameter mismatch) |
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what are the indications for renal stenting?
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->70% stenosis of RA and poorly controlled HTN
-aortoostial lesions -restenosis lesions -suboptimal balloon angioplasty -renal failure and assoc. renal artery stenosis -hemdialysis patients w/ stenosis |
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explain some contraindications for renal artery stentting?
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-relative, and not absolute
-risk to benefit must be considered: -atheroembolic disease(shaggy ao) -renal artery aneurysms |
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what (on a ROC curve), gives teh likelihood ratio for the value of the test?
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the slope of the tangent line at a cutpoint gives the likelihood ratio fr that value of the test
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how is cavication threshold predicted?
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-by the ratio of peak rarefractional pressure to the square root of the frequency(MI describes likely hood of cavication-should be <1)
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cutpoint
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-point on the graph where above the test is considered abnormal, and below is considered normal
-cutpoint can be changed by changing criteria for what constitutes a positive test -changing the cutpoint alters the sensitivity and specificty of a test |
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formula for prevalence
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true positives + false negatives/all people
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explain transient caviation
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-bubble implode
-high requencies and large intensities are required to preoduce this effect(i.e.100w/cm2 at 1 MH |
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When is intensity the highest? When is acoustic power the highest? lowest?
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highest intensity=pulsed doppler
highest acoustic power=color lowest acoust power=m-mode because PRF is only 500/s |
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What is considered the max intensity of u/s?
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SPTA-spacial peak, temporal average
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do chi square example E in notes
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do it, as well as calculations on the back.
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What is max heat related to?
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SPTA:Descripter used in the AIUM statement on mammalian bioeffects
SPTA=SP/SA |
