Exam 4 - Canine Chronic Valvular Disease Flashcards
T/F: approximately 10% of dogs have heart disease & approximately 30% will develop heart failure
true
what is the number one cause of canine heart disease?
myxomatous mitral valve disease - canine chronic valvular disease
what breed is predisposed to develop mmvd?
cavaliers
what is the pathophysiology of canine cvd?
degeneration of the av valves & chordae tendinae - mitral & tricuspid valves (endocardiosis) with the left av valve being most commonly affected
why does cardiac remodeling occur in dogs with mmvd? what changes are seen?
occurs secondary to progressive mitral/tricuspid regurgitation
left atrial & ventricular chamber dilation & left systolic dysfunction
what is a common sequelae to mmvd? what is a rare one?
pulmonary hypertension
rare - clinically significant arrhythmias are uncommon
what is the median time to developing CHF in stage B2 for an animal on pimobendan?
42 months
what is the preclinical/asymptomatic stage of CHF?
ACVIM stage B1 & B2
how is stage B1 & B2 of CHF diagnosed?
easy to diagnose - characteristic mitral heart murmur heard in small, older breed dogs
what is the clinical stage of CHF?
ACVIM stage C & D
what are the clinical signs attributed to in CHF stage C & D?
left sided CHF with pulmonary edema
left mainstem bronchus compression secondary to marked left atrial enlargement
pulmonary hypertension
what is stage A according to the ACVIM classification of heart failure?
at risk for heart failure - apparently healthy animal, but high risk for developing CVD or DCM
what is stage B according to the ACVIM classification of heart failure?
animal at risk for heart failure - dogs with CVD or DCM that have never had clinical signs of CHF attributable to CVD or DCM
what are stages C & D in regards to the ACVIM classification of heart failure?
stage C - past or current signs/symptoms of CHF
stage D - end stage CHF, refractory to standard treatment
what is the classification of stage B1?
asymptomatic dogs with CVD or DCM that is not severe enough to meet criteria used to trigger the use of medical treatment to delay the onset of heart failure
what is the classification of stage B2?
asymptomatic CVD or DCM that is severe enough to result in cardiac remodeling (left atrial & left ventricular enlargement) sufficient to recommend treatment before the onset of clinical signs
what is the current recommendation for CVD/DCM in a dog in stage A?
annual auscultation
what is the current recommendation for CVD/DCM in a dog in stage B1?
diagnostic tests for staging, scheduled follow-up & client education - no therapy recommended
what is the current recommendation for CVD/DCM in a dog in stage B2?
diagnostic tests for staging, scheduled follow-up & client education - pimobendan recommended
what is the current recommendation for CVD/DCM in a dog in stage C?
therapy required - furosemide, pimobendan, ACEi, spironolactone
scheduled follow-up & client education
what is the current recommendation for CVD/DCM in a dog in stage D?
therapy required - symptom specific recommendations
scheduled follow-up & client education
what are the EPIC conclusions in regards to time to onset of CHF or cardiac death?
extends symptom free survival
60% = 15 months (10% increase in your dogs health-span)
1/3 decreased risk of CHF every day for the rest of the dog’s life - majority of benefit attributable to delay onset of CHF
*extends overall survival
*safe & well tolerated
*results are of clinical relevance
what are the 4 possible diagnostic criteria for stage B2 of CVD?
documentation of ‘sufficient cardiomegaly’
(echocardiogram)
1. left atrial/ventricular chamber dilation
(thoracic rads)
2. increased vertebral heart size (> 11.5)
3. increased vertebral left atrial size (> 3.0) - progressive radiographic cardiac enlargement
4. > 0.5 increase in VHS over 6 months or increase > 0.08 in a month
what is the typical murmur heard in a dog with stage B2 CHF?
mitral regurgitation murmur - left systolic apical, typically grade 3/6
what criteria must be met to diagnose an asymptomatic older small breed dog with a mitral valve murmur in stage B2 CHF?
must meet or exceed any one of the following 4 criteria!!!!!
(echocardiogram)
1. left atrial/ventricular chamber dilation
(thoracic rads)
2. increased vertebral heart size (> 11.5)
3. increased vertebral left atrial size (> 3.0) - progressive radiographic cardiac enlargement
4. > 0.5 increase in VHS over 6 months or increase > 0.08 in a month
what is the highest priority test to diagnose CVD? why?
echocardiography - it is the most sensitive & specific method to diagnose & stage CVD making it the priority test
what should you do when evaluating chest rads that weren’t taken at a 6 month interval?
divide the difference in VHS by the number of months between the visits - a change per month that is > 0.08 also represents progressive cardiomegaly in dogs with stage B CVD
what are the differences in follow-up care in dogs with stage B1 versus stage B2 CVD?
stage B1 - no treatment, follow up every 6-12 months, weekly monitoring of home respiration rates, & modest dietary sodium restriction
stage B2 - pimobendan (0.23-0.3 mg/kg every 12 hours), recheck every 4-8 months, daily monitoring of home respiration rates, & modest dietary sodium restriction
if you have a dog in stage C CVD with no significant arrhythmias, what treatment is recommended?
- pimobendan & furosemide
- ACEi
- spironolactone
if you have a dog in stage C CVD with significant ventricular arrhythmias, what treatment is recommended?
- pimobendan & furosemide
- ACEi & sotalol
- spironolactone
if you have a dog in stage C CVD with atrial fibrillation, what treatment is recommended?
- pimobendan & furosemide
- ACEi & diltiazem
- spironolactone +/- digoxin
after the initial diagnosis of L-CHF secondary to mmvd is made, what should be done?
follow-up in 10-14 days & scheduled follow-ups every 2-4 months or sooner if signs of decompensation develop or after a significant change in meds
what is heart failure?
inability of the heart to meet tissue perfusion needs with normal filling pressures
what is backward heart failure?
‘wet’ heart failure
left sided CHF - cardiogenic pulmonary edema
right sided CHF - ascites +/- pleural effusion
left & right sided - biventricular failure
what is forward heart failure?
‘cold’ - poor peripheral perfusion
what diagnostic tests should be performed if you suspect forward heart failure?
blood pressure - low
pre-renal azotemia
venous O2 < 24mmHg
increased blood lactate
what is the typical history & physical exam findings of a dog with suspected ‘forward’ heart failure?
lethargic, dull/depressed, exercise intolerance, weakness, collapse, syncope
+/- murmur, relative tachycardia, cool extremities, weak pulses, increased CRT, cyanosis, & low body temperature
what is the typical history & physical exam findings of a dog with suspected ‘backward’ right-sided heart failure?
pot belly/abdominal distension, diarrhea, dyspnea, tachypnea
+/- murmur/relative tachycardia, ascites with jugular distension & positive hepatojugular reflex, pleural effusion - muffled lung and/or heart sounds
what diagnostic tests should be performed if you suspect right-sided backward heart failure?
echocardiogram, abdominal ultrasound, thoracic radiographs, abdominocentesis, & pleurocentesis
what is seen on rads in a dog with left sided backward heart failure?
cardiogenic pulmonary edema
what diagnostic tests should be performed if you suspect left-sided backward heart failure?
thoracic rads, therapeutic challenge, blood biomarkers - n-terminal pro b type naturetic peptide
what is the typical history & physical exam findings of a dog with suspected ‘backward’ left-sided heart failure?
cough, tachypnea, dyspnea, acute history, depressed, anorexia, weight loss, orthopnea
+/- murmur, relative tachycardia, normal lung sounds, crackles, wheezes, & increased bronchovesicular sounds
why do dogs get a cough with CVD?
there is compression of the left mainstem bronchus secondary to left atrial enlargement & primary airway disease complicated by heart enlargement
can mimic primary respiratory disease - can occur alone or in combination with CHF, small (chronic bronchitis) & large airway (collapsing trachea) disease
what is the therapy for a cough in a dog with cvd?
therapy is palliative not curative - therapy targets underlying airway disease & CVD
what are some signs that don’t support a diagnosis of CHF?
slow heart rate, sinus arrhythmia, no gallop sounds, normal pulses, loud lung crackles, normal VHS, no pulmonary infiltrate
what are some surgical options for CVD?
open surgical repair on cardiopulmonary bypass & transcatheter edge to edge repair (v-clip)
what is the 4th most common reported cause of canine death?
CVD
T/F: CVD is rare before 5 years of age
true
T/F: 30% of stage B2 dogs will develop CHF
true
