Equine Cardiology Flashcards
what types of murmurs are common in horses?
soft systolic
how many heart sounds are normal to hear in a horse?
two
three
four
split S2
how are cardiac murmurs described?
timing
intensity- grade
point of maximum intensity
quality/pitch
what are the causes of diastolic murmurs?
aortic insufficiency- common
pulmonic insufficiency
what can cause a regurgitant quality systolic murmur?
mitral regurgitation
tricuspid regurgitation
what are the options for quality/pitch of a murmur?
musical
harsh/soft
squeak
shape- crescendo/decrescendo, band/plateau
what diagnostic procedures can be done for a cardiac murmur?
ECG
echocardiography
biomarkers
what is electrocardiography useful for in horses?
rate and rhythm only
base apex lead
what is holter ECG useful for?
intermittent arrhythmia
monitoring of clinically relevant arrhythmia during treatment
monitoring at-risk patients
what heart rate is expected in a horse at a walk?
50-80 bpm
what heart rate is expected in a horse at a trot?
80-120 bpm
what is the best non-invasive technique of looking at the heart in real time?
echocardiography
what are some indications for an echo?
pre-purchase exam
evaluation of murmurs or arrhythmia
unexplained poor performance
what does elevated cardiac troponin-I indicate?
myocardial injury
ruptured aortic jet lesion
sepsis
endurance racing
is there an association between presence of a murmur and racing performance?
no
what with a “functional” murmur would indicate an echo should be performed?
getting louder over time
what left-sided systolic or aortic murmurs should you recommend an echo for?
grade III-VI/VI
what is normal heart rate in a horse?
23-44
what are the causes of ejection quality systolic murmurs?
innocent/functional- common
fever
anemia
ventricular septal defect
aortic stenosis- rare
pulmonic stenosis- rare
what is the heart rate for cantering and galloping?
canter: 120-150
gallop: 150-200
what should you look at with echocardiography?
measure chamber size and wall thickness
valve motion
direction, velocity, turbulence of blood flow
systolic and diastolic function
when might you see a globoid heart with radiographs?
pericarditis/pericardial effusion
when should an echo be performed?
previously diagnosed functional murmur louder over time
grade >III/VI left sided systolic or aortic murmur
grade >IV/VI right sided systolic murmur
suspected congenital heart lesion
continuous or combined systolic-diastolic murmur
clinically important arrhythmia
suspected myocardial injury
suspicion of congestive heart failure
what does atrial fibrillation require?
a trigger to start and substrate to maintain it
what is paroxysmal atrial fibrillation?
resolves spontaneously- usually race horses, resolved by 24 hours
when does the loss of atrial contribution in atrial fibrillation become more important?
during exercise or with underlying heart disease: heart rate increased
does atrial fibrillation shorten the lifespan of most horses with it?
no
when are horses not suitable to be ridden?
cannot achieve performance
maximal heart rate exceeds 220
ventricular ectopy seen with exercise
when should you treat atrial fibrillation?
persists >48 hours
normal heart rate
no other heart disease or electrolyte abnormalities
when should you not treat atrial fibrillation?
secondary to underlying heart disease
left atrial diameter enlarged
resting tachycardia
how can you convert atrial fibrillation?
quinidine sulfate
transvenous electrical cardioversion
does quinidine sulfate or transvenous electrical cardioversion have a better conversion rate for atrial fibrillation?
transvenous electrical cardioversion is better with longer-standing atrial fibrillation
what is the success rate of converting atrial fibrillation?
65-90%
better if less than a month, less likely if more than 3 months
what can cause acute onset loud murmur?
bacterial endocarditis
ruptured chordae tendinae
ruptured sinus of valsalva
previous murmur that was quiet and missed becomes louder
what does aortic regurgitation present as?
diastolic “musical” murmur
water hammer pulse
very common older horses
what is a good indicator of severity of aortic regurgitation?
arterial pulse quality: bounding
intensity of murmur is not
what is the prognosis of aortic regurgitation?
older horse with mild: excellent
young horse with severe: poor
what is the prognosis of ruptured chordae tendinae or sinus of valsalva?
grave
how can you treat ventricular tachycardia?
lidocaine
magnesium sulfate
treat underlying disease
what are the most common sites of endocarditis in horses?
aortic and mitral valves
what is the prognosis of endocarditis?
poor to guarded for both survival and performance
what is the most common congenital heart lesion in horses?
ventricular septal defect
