Test 1: 15+16: large animal Flashcards
2nd degree AV block has what type of rhythm
regularly irregular
pause or dropped beat
S4 not followed by S1
conduction through AV node blocked
2nd degree AV block
missed beat: conduction through AV node blocked
2nd degree AV block can be a normal finding that —
goes away with exercise or drugs that increase sympathetic and decrease parasympatetic tone
from high vagal tone
15% of short EKG will show, 44% on 24 hr EKG
— is a variation in P-P interval due to changes in the SA node
sinus arrhythmia
sinus arrhythmia in dogs vs horses
dogs: controlled by breathing, HR changes with exhale inhale
large: not as common, but can be in athletic horse with high vagal tone
no clinical relevance
change in P-P interval due to changes in SA node
irregularly irregular = AFib
R-R interval
wobbly line
clinical signs of Afib
- High intensity exercise horse presented for poor performance
- Incidental finding in low intensity/pleasure riding horse
- Secondary to systemic illness
- Secondary to severe valvular disease and atrial enlargement
what can cause Afib in horse
- High vagal tone
- Atrial enlargement and remodeling
- Transient potassium depletion
- Sweating, diuretics (furosemide), bicarbonate milkshakes
- Atrial (supraventricular) premature complexes
- Atrial myocardial inflammation
- Excessive thyroid hormone administration or iodine containing supplements
auscultation of Afib in large animals
irregularly irregular
variable heart sounds and pulses
no S4
heart rate normal unless in CHF or draft breed
HR in dogs, humans, and cattle will be increased
if Afib is first seen what should you do
check meds, electrolytes, cardiac troponin, echo (atrial enlargement)
wait, may spontaneously convert
when to not convert Afib in a horse
atrial enlargement
severe myocardial dysfunction
HR >60bpm
hyperthyroid
can be happy and healthy with normal activity
prognosis of cardioversion of Afib after 4 months
successful cardioversion 80%
can recurr 60%
if underlying heart disease worse odds
what drug used to medically cardiovert a horse
quinidine sulfate
85% success rate
can cause seizures, ataxia, edema, QRS prolongation
associated with high plasma concentration
how to convert Afib in horse
quinidine sulfate
or
TVEC
adverse effects of TVEC
GA
myopathy, 3rd degree AV block, sudden death
how does quinidine work
class 1A AA
Na blocker
increases effective refractory peroid
slows conduction and dirupts reentry circuits
vagolytic (positive chronotrope)
negative inotrope (at high doses only)
chemical conversion of Afib in horse
why do you need an exercising EKG on horse with Afib
to look for other arrhythmias or high HR that would be dangerous
horse can collaspe or die
3 causes of murmur
regurgitation
shunts
stenosis
7 ways to characterize murmur
- Grade
- Timing
- Duration
- Quality
- Shape
- Location = PMI
- Variable
systole occurs with what heart sounds
S1-S2 (short)
+ pulse
diastolic murmur is caused by
aortic regurgitation
can also be pulmonic regurg, mitral and tricuspid stenosis
aortic regurgitation will cause — mumur
1-6/6 decrescendo diastolic murmur
normal finding in horse over 10 years old, usually asymptomatic
if bounding pulses= severe or moderate
what kind of pulse for aortic regurgitation
mod or severe will cause bounding peripheral pulse
blood leaks through aortic valve causing decrease in diastolic pressure, difference in pulse pressures is greater= bounding
Aortic regurgitation with exercise will cause
- ventricular enlargement and remodeling
- decreased coronary perfusion
- shortened diastole caused by high HR
- increased oxygen demand
- increased sympathetic tone caused by the exercise
leads to arrhythmias
what kind of murmur for TR
right systolic murmur
grade = severity
usually good prognosis
VSD will cause — murmurs
right= systolic mumur (shunt >3 panystolic PMI TV area) (shunt moving left to right, shoots toward stethoscope)
left= relative PS (< R cresc-decresecendo PMI PV)
systolic murmurs with right side louder then left side
why do horses with bilateral systolic murmurs need echo
congenital heart disease (VSD)
can cause mild to severe issues based on size and pressure of defect
right sided systolic murmur=
TR
A loud L sided systolic murmur is — until proven otherwise
MR
Mitral regurg will cause — murmur
loud left sided systolic murmur
grade 1-6 with no correlation with severity
right sided only systolic murmurs are —
TR
diastolic murmurs=
AR
what are signs of MR in horse
loud Left sided systolic murmur
Exercise intolerance
* Increased heart rate
* Increased respiratory rate and effort
* Cough
* Edema
* Arrhythmias (AF)
how to tell physiologic vs mitral regurg
how to tell MR from MV prolapse
how to tell systolic murmur on left side
when to worry about left sided systolic murmur
If 3-6/6 and holo or pansystolic
* If band shaped and holo or pansystolic (mitral regurg)
When the horse has other signs of heart disease:
* Increased respiratory rate or effort
* Atrial fibrillation
* Exercise intolerance/poor performance
continuous mumur in young animals are
PDA
continuous murmur in adult is caused by
aortocardiac fistula
- Connection from aortic root-RV, RA or LV
- Signs may be distress, arrhythmia or colic
- Associated with ventricular arrhythmias
- Unsafe to ride/risk sudden death
- Life expectancy days-months
what can cause pericardial disease
idiopathic, bacterial, viral, traumatic, neoplastic
hardware disease
PE of animal with pericardial disease
Physical examination: Tachycardia, tachypnea, fever, pericardial friction rub,
muffled heart sounds, jugular and generalized venous distension, weak pulse, ventral edema, weight loss
A loud left sided systolic murmur is – until proven otherwise
MR
A diastolic murmur is — until proven otherwise
AR
A right sided systolic murmur, if only right is — until proven otherwise
TR
A right sided systolic murmur, if accompanied by systolic murmur over the pulmonic valve is a — until proven otherwise
VSD
An irregularly irregular rhythm is — until proven otherwise
Afib
how to diagnose pericardial disease
echo
pericardiocentesis
Xray
can give antimicrobials, steroids and drain the effusion
bovine cardiac lymphosarcoma will cause
cancer in abomasum, uterus, kidney, and heart
Mass in right atrium, infiltrating pericardium and/or hemorrhagic pericardial effusion
Neoplastic lymphocytes in pericardial or pleural fluid
caused by bovine leukemia virus
symptoms of infectious valvular disease
intermittent fever, weight loss, depression, anorexia, lethargy, intermittent lameness, synovial distension, tachycardia
May have no auscultable murmur (50% cattle)
effect different valves:
Horse: M>A>T>P
Cattle: T>P>M=A
what valves are infected by endocarditis in large animals
Horse: M>A>T>P (left side)
Cattle: T>P>M=A (right side)
need to confirm with blood culture
