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19 Cards in this Set
- Front
- Back
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What are some clinical signs of CV dz?
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failure to grow or thrive, exercise intolerance/poor performance, tachycardia, arrhythmia, heart murmur, weak pulse, poor perfusion (↑ CRT, cold extremities), cough, prominent jugular pulse, peripheral or ventral edema, ascites, cyanotic mm, pleural effusion, syncope
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What are the components of a cardiac workup?
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PE: mm, CRT, HR, rhythm, pulse quality (pulse deficits, apical beat, thrills), jugular pulse, jugular venous distention, cardiac auscultation
-NORMAL to hear all 4 heart sounds (or 2 or 3) echo ECG: limited usefulness in horses BP: not commonly done CBC, Chem, ABG thoracic rads: limited value contrast angiography +/- cardiac isoenzymes, blood cultures |
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What are the most common causes of murmurs that occur during
a. systole b. diastole |
widely radiating murumurs more likely pathologic than localized murmurs, regardless of intensity
a. “flow”: benign, functional -low intensity, highly localized -occur early in systole - louder w/ ↑ CO AV valve insufficiency semilunar valve stenosis L: #1 flow, #2 mitral regurg R: #1 tricsupid regurg, #2 VSD b. #1: aortic regurg: 99% (semilunar valve insufficiency) “flow”: not very common -very faint -young horses usually AV valve stenosis |
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What are some characteristics of PDA in horses?
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closure may be delayed or ductus may remain open in septic foals: partial return to fetal circulation
PDA in older foal or adult almost always accompanied by other congenital cardiac defects murmur often only systolic: careful, b/c most foals will have systolic murmur for 1st few days of life |
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ventricular septal defect
a. defect occurs where b. PE findings c. px |
a. usually subaortic
b. L --> R shunt: normal PaO2 -clinical significance depends on size of defect -systolic murmur, PMI on R side c. high athletic potential: defect < 2.5 cm, shunt velocity > 4 m/sec, no aortic regurg -pleasure horse: defect < 3.5 cm, shunt velocity > 3 m/sec, no to mild aortic regurg -↓ life expectancy: defect > 3.5 cm, shunt velocity < 3 m/sec, no to severe aortic regurg |
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What is the difference b'twn physiologic & pathologic arrhythmias?
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physiologic: d/t high vagal tone
pathologic -1º: cardiac -2º: electrolyte disturbances, GI/metabolic disturbances, autonomic nervous system, toxicities |
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AV block
a. 1st degree b. 2nd degree c. 3rd degree |
a. PR interval > 0.4 s
b. "dropped beats" (most common) c. AV dissociation: ALWAYS pathologic 1st & 2nd degree often NORMAL d/t high vagal tone, esp. in athletes, startle horse to obliterate |
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atrial fibrillation
a. characteristics b. causes |
a. no synchronous atrial contraction: no S4 on auscultation, no P waves on ECG (f waves)
-irregularly irregular HR: irregular R-R interval on ECG, normal QRS -varying intensity of heart beats/pulses: may have pulse deficits -HR may be normal or ↑: arrhythmia less obvious at faster rates b. electrolyte/acid-base disturbances -metabolic, GI disturbances -autonomic nervous system imbalances -anesthesia, drug toxicities -enlarged atria d/t underlying cardiac dz -idiopathic |
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mitral regurg
a. murmur b. causes c. clinical signs d. echo findings |
a. systolic band shaped murmur heard best over L heart apex
b. congenital valve abnormality, endocardiosis (most common), ruptured chord, bacterial endocarditis, myocarditis or CM w/ stretching of valve annulus c. range from none to HF d. severity determined by extent of regurgitant jet into LA & signs of left heart enlargement -left cardiac enlargement: rounding of apex, ↑ chamber volumes, ↓ LV free wall & septal thickness (dilative hypertophy) -heart is initially hyperdynamic, w/ contractility ↓ as horse progresses toward HF |
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aortic regurg
a. murmur b. causes c. clinical signs d. echo findings |
a. diastolic decrescendo murmur heart best over L heart base, can be musical or honking
-loudness does NOT correlated w/ severity -strong to bounding pulses b. usually found in older horses -usually caused by degenerative changes of valve c. rarely interferes w/ performance unless prolapsing valve cusp, concurrent mitral regurg, myocardial dz, or arrhythmia d. look for aortic valve thickening or cusp prolapse -high frequency vibrations of septum or septal leaflet of mitral valve -look for evidence of mitral regurg -determine degree of cardiomegaly -severity based on size of regurgitant jet, degree of L heart enlargement, presence of arrhythmia |
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tricuspid regurg
a. PE findings b. cause c. clinical signs |
a. systolic band shaped murmur heard best over R heart apex
-jugular pulsations, venous distention b. primary is rare, can be assoc. w/ other diseases causing right heart enlargement (ex. CM) c. none to signs of RHF |
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myocarditis
a. etiology b. clinical signs |
a. myocardial inflammation d/t bacteria, viruses, or parasites
-most common causes: influenza, Strep equi -->cardiac dysfunction, poor contractility, arrhythmias b. depression, anorexia, lethargy, fever, inc. cardiac troponin |
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What are some causes of cardiomyopathy?
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toxins: ionophores, gossypol, plants, molybdenum, sulfates
deficiencies: vitamin E/selenium, copper other unknown |
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myocardial dz: myocarditis, CM
a. dx b. tx |
a. ECG, echo, find underlying dz
b. tx underlying cause symptomatic & supportive care -tx HF: furosemide, digoxin -tx arrhythmias |
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bacterial endocarditis
a. clinical signs b. dx c. tx |
a. fever, depression, anorexia, wt. loss
-can cause valvular regurg &/or stenosis b. CBC (chronic infection), blood cultures, echo c. difficult to tx if extension valvular lesions -aggressive AB therapy for prolonged period: based on C/S -supportive care |
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pericarditis
a. causes b. clinical signs c. dx d. tx |
a. most commonly assoc. w/ viral resp. dz
b. may be acutely effusive or chronically constrictive -jugular v. engorgement w/o pulsations -muffled heart sounds or friction rubs -acute: signs of cardiac compromise, pain c. CBC (chronic infection), echo, +/- thoracic rads, +/- pericardiocentesis d. mild: monitor fluid accumulation & supportive care (ABs +/- steroids, etc.) suppurative or restrictive: pericardiocentesis, pericardial stripping, rib resection |
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What is the tx for CHF in horses?
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ID & tx underlying cause: infection, toxicity, GI dz, etc.
tx arrhythmias if necessary ↓ edema: furosemide ↑ contractility if necessary: digoxin currently, no useful ACE inhibitors for horses |
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atrial fib
a. clinical signs b. dx c. tx |
a. variable: none --> ↓ exercise performance --> CHF
b. ECG, electrolytes, blood gas, cardiac isoenzymes (troponin), echo c. correct underlying dz if 1 exists -quinidine: more successful if no underlying cardiac dz, duration of A fib is < 2-4 mo. *process is labor intensive requires expertise; moderately toxic at therapeutic doses +/- digoxin -cardioversion: electrical shock applied to heart (new) |
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What are some limitations of ECG in horses?
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extensive penetration of Purkinje fibers thru out myocardium
explosive depolarization bulk of myocardial depolarization is silent to ECG d/t multiple cancellations ECG records a small part of septum |
