Congenital murmurs

Congenital murmurs

1. Aortic stenosis

   • More common in Boxer, GSD, Newfoundland, Rottweiler, Golden retriever
   • History: exercise intolerance, syncope, acute death, left sided CHF (dyspnoea, tachypnoea, cough)
   • Clinical exam: weak pulse, harsh systolic murmur left base +/- left CHF
   • Rads often normal or LHS enlarged, cardiac silhouette elongated, post valvular dilation of aorta
   • ECG: tall R waves, ventricular premature complexes, ST segment depression
   • Echo: LV hypertrophy, aortic valve dysplasia, sub-valvular narrowing of aorta, high velocity and turbulence across aorta
   • Mild cases: no treatment, good prognosis, severe cases: beta-blockers and Ca channel blockers, guarded prognosis

2. Patent ductus arteriosus

   • More common in Springer spaniel, Shetland sheepdog, Collie, GSD, CKCS, Poodle
   • History: exercise intolerance, left sided CHF (dyspnoea, tachypnoea, cough)
   • Clinical exam: continuous murmur left base, water-hammer pulse
   • Rads: dilation of the heart (initially left then both), increased lung vasculature, aortic/pulmonic/left auricular bulge
   • ECG: tall R waves
   • Echo: turbulent blood in pulmonary artery, continuous flow through the ductus arteriosus at high velocity, visible ductus
   • Treatment: surgical ligation or coil implant to close off the ductus arteriosus, left sided CHF treated with diuretics and ACE inhibitors, prognosis excellent if treated early
   • Reversed PDA: excessive overload of lungs may lead to pulmonary hypertension and right to left shunting
     • Animals present with hindquarter weakness/caudal cyanosis and may develop polycythaemia due to hypoxia
     • Surgical treatment may result in right sided CHF and prognosis is poor

3. Pulmonic stenosis

   • More common in Beagle, West Yorkshire terrier, English bulldog, Bull mastiff, Boxer, Cocker spaniel, Airedale terrier
   • History: exercise intolerance, syncope, acute death, right sided CHF (ascites, dyspnoea)
   • Clinical exam: weak pulse, harsh systolic left base murmur, ascites
   • Rads: reduced lung vasculature, RV hypertrophy, pulmonic bulge
   • ECG: deep S waves
   • Echo: RV hypertrophy, thickening of pulmonic valve
   • Mild cases no treatment, good prognosis
   • Severe cases beta-blockers, balloon valvuloplasty, patch graft, guarded prognosis

4. Ventricular septal defect

   • Majority are small peri-membranous defects and asymptomatic
     • Occasionally may get over circulation of the lungs, left sided CHF
     • Rarely get pulmonary hypertension, right to left shunting
   • History: exercise intolerance, left sided CHF (dyspnoea, cough)
   • Clinical exam: systolic murmur right side, good pulse
   • Rads: cardiomegaly of whole heart, increased lung vasculature
   • ECG: tall R waves
   • Echo: defect in septum, turbulent flow across the defect
   • Asymptomatic require no treatment, if CHF its treated with diuretics and ACE inhibitors, no surgical treatments

5. Tetralogy of Fallot

   • Combination of 4 disorders
     • Pulmonic stenosis
     • Large ventricular septal defect
     • Over-riding aorta
     • RV hypertrophy
   • History: collapse, dyspnoea, cyanosis, exercise intolerance
   • Clinical signs: +/- murmur, +/- cyanosis, +/- dyspnoea
   • Rads: RV enlargement, decreased lung vasculature, pulmonary artery bulge
   • ECG: deep S wave
   • Echo: large VSD, over-riding aorta, right to left shunting across VSD
   • Phlebotomy, hydroxyurea, beta-blockers, palliative surgery
   • Prognosis is guarded

6. Mitral valve dysplasia

   • Clinical exam: systolic murmur over mitral valve +/- diastolic murmur
   • May develop left sided CHF
   • Treatment similar to mitral valve endocardiosis
   • Prognosis depends on severity

7. Tricuspid valve dysplasia

   • Clinical signs: asymptomatic, exercise intolerance, syncope, ascites, systolic murmur right apex, right sided CHF
   • Rads: RA enlargement
   • ECG: splintered QRS complex
   • Echo: abnormal appearance and position of tricuspid valve
   • More common in Labrador, Weimaraners and other large breeds