LA Cardiology (Estell) Flashcards
Most common etiologies (4) of cardiac murmurs in LAs
Acquired valvular diseases:
1. degenerative / idiopathic
2. bacterial endocarditis
3. ruptured chordae tendinae
4. aortuc rupture
Diastolic murmurs of valvular insufficiency are caused by…
….Aortic valve regurg
Systolic regurg murmur is caused by:
mitral (L) or tricuspid (R) valve regurg
What conditions require an equine athlete to receive a cardiac worl-up?
- Grade 3/6 murmur
- Arrhythmia
- Cardiac murmur + unexplaiend exercise intolerance
grade 3: readily heard, of equal inensity to S1 & S2
What would be auscultated on a horse with mitral valve ruptured chordae tendinae
- left-sided, honking or musical murmur
generally results in severe MV insuff. & fairly rapid CHF progression
What valve are cattle more likey to get ruptured chordae tendinae and how?
Tricuspid –> occurs 2º to bacterial endocardiitis or lymphoma
Aortic rupture
- definition
- signalment
- Aorta ruptures into pulmonary artery, pericardium, or into right side of heart -> peracute death
- Older horses; stallions and Friesians
Clinical signs of congential cardiac disease
- failure to thrive; lethargy
- loud heart murmur
- camelids have high incidence of congenital anomalies
Signs a murmur is congenital cardiac disease-associated murmur vs. an innocent/flow murmur that is common amongst neonates
PDA is a normal finding in equine and ruminant neonates of what age?
< 7 days old
Cor pulmonale
right-sided heart disease 2º to pulmonary dysfunction (pulmonary aa. hypertension -> RV dilation/hypertrophy -> right-sided HF)
What species is cor pulmonale most common?
cattle
2 causes of Cor pulmonale in cattle
1. High altitude disease / Brisket disease (exacerbated by pre-exisiting lungowrm or parasitic infection, cold weather, bronchopneum., genetics)
2. Chronic lung disease
Lower O2 concentrations -> hypoxic vasoconstriction of pulm. a. -> pulm. hypertension
Sequela of pericarditis
fluid accumulation b/w visceral and parietal pericardium (peridcardial effusion) -> can lead to cardaic tamponade
main CS = muffled heart sounds
Effusive pericarditis appearance on u/s
anechoic fluid accumulation
Fibrinous pericarditis
fluid + fibrin in the pericardium
Constrictive pericarditis
fibrous tissue ( = chronic inflammation/scar tissue) of the pericardium/myocardium -> compression of the heart, permanently impairing diastole
Most common etiologies of pericarditis of ruminants vs equines
Ruminants: traumtic reticulopericarditis (poorer prognosis)
Equines: Idiopathic, viral, bacterial - Actinobacillus spp. (result of ingestion of eastern tent caterpillars)
Where is lymphoma most likely to occur in LAs? Specifically in cattle?
Large Animals: RA, mediastinun, pericardium
Cattle specifically: RA, Uterus, Spine, Abomasum, LNs
non-pathologic arrhythmia characteristic
present at rest and disappear with an increase in sympathetic tone
Afib
- irregulary irregular
- lack of P waves
- most common patholgcic arrhythmia in horses
Quinidine sulfate
Na+ channel blocker, prolongs refractory period (time in b/w beats) + slows AP conduction
use in Afib tx
Transvenous Electrocardioversion
transvenous catheters in RA and PA via jug vein -> delivery of shocks precisely on R wave
When do cattle typically develop (pathologic) arrhythmias
when off feed or with GI dz
When do small ruminants and camelids develop pathologic arrhythmias
w/ urinary tract obstuction or uroabdomen
White Muscle Disease & VitE/selenium deficiency pathogenesis
VitE and selenium = cofactors in antioxidant enzymes –> deficiency results in free radical accumulation –> membrane destruction of skeletal and cardiac muscle -> myocarial necrosis, fibrosis, & mineralization
Ionophore toxicity and myocarditis in horses
growth-promoting feed additive for livestock -> if horses accidentally eat them (grain overload) –> disrupted cardiac membrane -> cell necrosis, arrhythmia and poor systolic function
tx = gastric lavage + charcoal + arrhthmia mgmt. + anti-fibrotics + VitE
prognosis: may cause acute death 12-36h after ingesion; can devleop CHF if systole dysfunction continues; some horses recover (normal LV fractional shortening on M-motion is positive indicator)
