8/25 - Canine Congenital Heart Problems

Subaortic Stenosis

What heart defect is also called SAS and is common in Newfoundlands, golden retrievers, rottweilers, boxers, GSDs, bulldogs, great danes, GSHP, and bouvier cats? It is characterized by a systolic crescendo/decrescendo murmur that is musical, loud over the left heart base, and can radiate anywhere. It involves an outflow tract obstruction, concentric hypertrophy, secondary mitral regurgitation, arrhythmias, and low output failure (syncope, sudden death). The murmur may not be heard until 2 years old, and diagnosis can be difficult (LV enlargement, post-stenotic dilation, hypertrophy, subaortic narrowing, SAM of anterior mitral leaflet, aortic dilation, turbulence).

Systole

Subaortic stenosis and pulmonic stenosis are characterized by a crescendo/decrescendo murmur on the left heart base in which phase?

50

More than what percent of subaortic stenosis dogs will die suddenly within 3 years? They are predisposed for endocarditis, and can be managed with b-blockers (relaxation, decrease afterload) and exercise restriction.

Pulmonic Stenosis

Which heart defect is also called PS and is common in bulldogs, mastiffs, samoyeds, schnauzers, westies, cockers, beagles, airedales, boykins, chihuahuas, and scottie terriers? It causes a systolic crescendo/decrescendo murmur loudest over the left heart base. It is usually caused by dysplastic valve leaflets and involves pressure overload (RV hypertrophy, RA enlargement) and post-stenotic dilation. Syncope, asymptomatic cases, and exercise intolerance can all be seen. Repair is with balloon valvuloplasty.

Coronary

Single anomalous what artery is a condition affecting dogs also predisposed to pulmonic stenosis, making balloon valvuloplasty a risky repair method in these dogs?

PDA

What heart defect (abbreviated) is when this structure fails to close, which normally occurs within hours of birth? It is a L-R shunt and occurs continuously, causing a continuous machinery murmur. It also causes volume overload of the pulmonary circulation, LA, and LV. Pressure overload of the RV can occur, plus increased pulmonic artery pressure causing reversal of the shunt. It is more common in female dogs, like maltese , poms, shelties, springers, keeshonds, bichons, poodles, yorkies, cockers, GSDs, and chihuahuas. Radiographs show enlarged LV and LA, overcirculated pulmonary vessels, and a ductus bump. Repair is with a transcatheter procedure, using coils or an Amplatz ductal occluder, or surgical ligation. Without treatment 50% will die within a year and CHF may also occur.

Sildenafil

Reversal of a PDA will cause pulmonary hypertension, which is treated with what drug? It also causes Eisenmenger’s physiology, RV enlargement, hypoxemia, and differential cyanosis.

Cats

Are VSDs more common in cats or dogs? It is usually the membranous portion of the septum involved and a systolic plateau murmur is heard on the right side. Volume overload will occur. A holosystolic murmur is best heard on the right, and can create a functional PS with concurrent left sided murmur. Echo is used to diagnose. Treatment depends on size, small defects can close and give a normal lifespan, but CHF and BP should be managed. Definitive repair is with occlusion devices and pulmonary banding. Cats with volume overload can be put on pimobendan, ACE inhibitors, furosemide, and/or the banding surgery.

ASD

What heart defect produces a split S2 sound and can produce RA or RV enlargement in severe cases? The fossa ovalis type is more common in dogs and the ostium primum type more common in cats.

Mitral

Dysplasia with what valve is most common in bull terriers, GSDs, danes, goldens, newfies, mastiffs, rottweilers, and cats? Males are more often affected. There will be shortened or elongated chordae, similar clinical signs to DVD just in younger patients, regurgitation/stenosis possible, and management for CHF required.

Tricuspid

Dysplasia with what valve is most common in labs, GSDs, boxers, weimeraners, danes, OESDs, and goldens, and is more common in males? It is caused by a displaced valve or leaflet. It will show right heart enlargement, R-CHF, and guarded-poor prognosis. Treatment can be attempted with pimobendan, ACE Is, spironolactone, furosemide, and diltiazem.

Fallot

Tetralogy of what is a condition of keeshonds and english bulldogs involving VSD, PS, dextropositioned aorta, and RV hypertrophy? It is characterized by exertional weakness, dyspnea, syncope, and cyanosis at rest. There will be a holosystolic right sternal murmur or a systolic ejection murmur at the left heart base. Polycythemia can occur that is absolute, due to chronic hypoxia, and involves hyperviscosity syndrome. Imaging can show underperfused lungs, RV hypertrophy, and reduced pulmonary vasculature. Treatment is with CHF management, phlebotomy, hydroxyurea, prognosis based on severity, and anastomosis or open heart bypass surgery.