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24 Cards in this Set
- Front
- Back
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Fetal circulatory basics
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Fetus = parasite with a scuba tank
Very little blood enters fetal lungs “Best” (highest oxygen content) blood enters RA via umbilical vein and shoots across foramen ovale to LV Least well oxygenated blood goes thru ductus arteriosus to body |
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Fetal circulation
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Oxygenated blood enters from umbilical vein from placenta
Crosses atrial septum to left atrium Left ventricle pumps highly oxygenated blood to heart and brain Less oxygenated blood returns to Right atrium, goes to right ventricle, and is pumped through patent ductus arteriosus into aorta |
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Common shunt lesions
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Shunt = to divert
-CV term = flow of blood thru an abnormal opening / connection Ventricular septal defect (VSD) Atrial septal defect (ASD) Patent ductus arteriosus (PDA) |
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Newborn and pulmonary reisistance
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Pulmonary resistance is higher than systemic before birth
-Hypertrophied medial layer of pulmonary arterioles -Keeps blood out of the lungs! First breath = drops resistance some Pulm bed fully “relaxed” by 4 - 8 wks Most shunt lesions do not have any physical findings or sx until pulm resistance drops “enough” Defects with intracardiac mixing and non-resticted pulm blood flow will develop CHF |
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Congestive heart failure in infants/children
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Pressure &/or volume load most common cause in infants/children
Hypovolemia detected by the body leads to: -Renal salt and water retention -Increased catecholamine levels -Myocyte hypertrophy Tachycardia Tachypnea / respiratory distress -Poor exercise tolerance -Feeding problems in infants Diaphoresis PE: lung findings, murmur &/or gallop, enlarged liver, poor perfusion, gray! -Rarely see peripheral edema, ascites |
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Murmurs
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Murmur = noise = blood flow = pressure difference
Not all murmurs are abnormal Graded by loudness Thrill = vibration due to a palpably loud murmur |
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Ventricular septal defect: overview
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Single most common CHD
-Septum formation complex Size of hole(s) determines presentation and physical exam Most close spontaneously Surgery if: -Huge hole with uncontrollable CHF -Hole large enough to cause pulm HTN -Large heart later, other complications |
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VSD anatomy
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Left to right shunt
-Higher pressure in LV compared to RV |
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Small VSD PE
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Child thriving
Heart not large Murmur begins at onset of systole (with S1) and continues as long as a pressure gradient exists betw left & right ventricles = holosystolic (IMPORTANT) Loudness & pitch vary with size & location |
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Stenotic lesions overview
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“Mediumly” common defects
Valvular stenosis most commonly -Pulmonary valve stenosis (PS) -Aortic valve stenosis (AS) Can involve LV or RV outflow tracts -Sub-aortic or infundibular Can involve branch pulm art, aorta -Branch pulm stenosis or coarctation |
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Pulmonary stenosis overview
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Stenosis due to lack of separation of the valve cusps
-"doming" Severity determines symptoms, physical exam and treatment needed Murmur due to turbulent blood flow thru narrowed valve orifice -RV may become hypertrophied if severe enough |
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Pulmonary stenosis: examination
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Usually no symptoms unless severe PS in a newborn
RV may feel enlarged if very thick -May have palpable thrill if severe Murmur occurs as blood ejected across valve orifice = systolic ejection murmur (crescendo decrescendo) Heard best over pulm art = LUSB -Usually radiates into lung fields |
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Pulmonary stenosis: treatment
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None needed for mild to mod PS
If severe stenosis or sick infant: -Balloon valvuloplasty -Rarely (now) surgical valvotomy Other types of stenoses may need surgical repair if severe enough |
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Cyanotic CHD: overview
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Bluish coloration of the skin / mucous membranes due to presence of deoxygenated hemoglobin in the circulation
Visible when the equivalent of 3-5 gm/dl of Hb has no oxygen in it Does not imply lack of oxygen -That depends on the amount of hemoglobin and how much is desaturated Can be on a lung or cardiac basis -Not breathing or sick lungs or . . . -Due to deoxygenated blood going directly to the body due to cardiac defect(s) |
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Acrocyanosis
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“Blue edges” = hands, feet
Normal finding in newborns Common in chilled children Does not mean true cyanosis Sluggish circulation in the periphery allows for extensive removal of oxygen by the tissues = blue |
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Hypoplasia/hypoplastic
Atresia/atretic Stenosis/stenotic |
Hypoplasia/hypoplastic = developed, but too small to be functional
Atresia/atretic = never formed at all -Valve atresia = door never opened; a solid shelf exists instead of a functional valve Stenosis/stenotic = only opens partially; obstructed |
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Cyanotic heart defects acronym
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Hey
Harry, This Turkey Tastes Terrible Hypoplastic right heart syndrome -Tricuspid atresia; pulm atresia Hypoplastic left heart syndrome Transposition of the great arteries Transposition of the pulmonary veins -Total anomalous pulm venous return (TAPVR) Tetralogy of Fallot Truncus arteriosus |
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Tetralogy of fallot: overview
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Most common of the cyanotic defects
Combination of 4 abnormalities due to conal septum malalignment (IMPORTANT): Large VSD (non-restictive to pressure) Pulmonary stenosis -determines how "blue" kid is Aorta over-rides the VSD Right ventricular hypertrophy |
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Tetralogy of fallot: variability
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The variable component is the severity of pulmonary stenosis
Cyanosis varies by the amount of obstruction of blood flow to lungs -May be minimally cyanotic (pink tet) if PS very mild -May be critically cyanotic (blue tet) if PS severe (ductal dependant) |
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Tetralogy of fallot: exam
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Palpably enlarged right ventricle
May have thrill Murmur is produced by the PS, not by the VSD Systolic ejection murmur radiates into lung fields Usually can’t hear pulmonary closure (single S2) due to stenosis |
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Tetralogy of fallot: Surgery
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Timing and nature of surgery depend on severity of cyanosis, size, etc
Palliation for some, then later repair -Surgical shunt placed --Get more blood to lungs Repair possible for most -Close VSD with patch and open up pulmonary outflow tract |
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Surgical repairs history and heart-lung machine
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Closed procedure means heart and lungs continue to function during surg
Open procedure requires use of extra-corporeal support to provide function of heart and lungs First closed procedure in 1938 (PDA) Open heart surgery first performed in mid 1950’s (ASD) Heart-lung machine -Circulation to heart and body -Oxygenation of blood -Removal of carbon dioxide -Temperature control -Administration of medications |
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Surgical basics, beginning and stopping heart
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Full monitoring & anesthesia
Midline sternotomy to expose heart Insert venous and arterial cannulae -SVC, IVC and ascending aorta Go on pump & begin cooling patient Clamp aorta proximal to cannula Stop heart with cardioplegia Perform repair |
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Surgical basics, starting heart
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De-air the left heart
Remove cross-clamp Heart action resumes spontaneously Allow heart to “take over” gradually from pump (wean from bypass) Remove cannulae Close up and go home |
