Congenital Heart Disease Flashcards
What is the pathophysiology of a PDA and how does it sound?
Ductus arteriosus remains patent between the aorta and pulmonary artery
Blood shunts from the aorta back into the pulmonary circuit leading to volume overload of the left side of the heart
Because aortic pressure is always higher than pulmonic pressure a continuous / machinery murmur is created which is louder in systole than it is in diastole
PMI - left heart base, far cranial
Radiation - may detect the systolic component on the LHS
Pulse quality - waterhammer pulse - large pulse pressure
What breeds are predisposed to PDAs?
Bitches
GSD, collies, bichon frise, CKCS
What are the clinical signs of PDA?
Continuous murmur - loudest at the left cranial heart base
Radiation to the axilla and elsewhere on the chest
(systolic murmur)
Secondary mitral valve regurgitation murmur
Waterhammer pulse
What radiographic signs will you se with a PDA?
Pathognomic triple knuckle
= aorta + pulmonary a. + left auricle bulge on DV view
What will you see on an ECG with a PDA?
P mitrale - left atrial enlargement
Tall R waves - left ventricular enlargement
Arrhythmias
What will you see on echo in a PDA?
Left atrial and ventricular enlargement
Dilated pulmonary trunk
Continuous flow trough the ductus with Doppler
How can you treat PDA?
Treat before the onset of CHF at 6y
Catheterise the PDA via the femoral artery and occlude with a duct occluder
What is the most common congenital defect in dogs?
Subaortic stenosis
- narrowing underneath the aortic valve lead the LVOT obstruction and forwards heart failure
= pressure overload of the left ventricle and concentric hypertrophy
What breeds are predisposed to subaortic stenosis?
Boxers, Newfoundlands, GRT
Uncommon in cats but when seen it is severe
What other pathology may you see with subaortic stenosis?
Reduced coronary perfusion leads to myocardial ischaemia
= arrhythmias
What does a subaortic stenosis murmur sound like?
Left heart base (4th ribspace)
Loud, harsh ejection type murmur
Mid-Systolic
Radiation to the right thoracic inlet
Pulses are weak
What changes will you see on echo with subaortic stenosis?
Post-stenotic dilation of the aorta
Turbulence at the aortic valve
High pressure gradient
0-40mmHg - mild
40-80 mmHg - moderate
>80mmHg - severe
What breeds have schemes for controlling subaortic stenosis?
Boxer
Newfoundland
How can you treat subaortic stenosis?
No surgical management available
Beta blockers and Pimobendan in severe outflow tract obstruction
Furosemide in CHF
What is the cause of pulmonic stenosis and what breeds is it common in?
Thickening around the pulmonary valve
Seen in cocker spaniels, CKCS, terrier
What are the clinical signs and pathophysiology of pulmonic stenosis?
Incidental heart murmur
Syncope or exercise intolerance
Obstruction at pulmonic valve increases afterload
This leads to concentric hypertrophy of the right ventricle and reduced myocardial perfusion = arrhythmias
What will you find on echo with pulmonic stenosis?
Thickened RV wall
Paradoxical septal motion - pressure in right ventricle has exceeded the left so the left ventricle is squashed
High pulmonary a. pressure gradient
What radiographic signs will you see with pulmonic stenosis?
Right ventricular enlargement
- increased sternal contact
- reverse d shape on a DV
Right atrium bulging
Pulmonary cap over the trachea
What ECG abnormalities will you see with pulmonic stenosis?
Negative QRS in lead 1
Deep S waves in lead 2 and 3
Right axis deviation
How can you treat pulmonic stenosis?
Ballon valvuloplasty
Surgical approach to dilate the valvular annulus
How do expect a murmur to sound in pulmonic stenosis?
Systolic
Left heart base (3rd intercostal space)
Radiates dorsally up the internal carotid
Normal peripheral pulses
What is one of the more common congenital cardiac defects in the cat?
Ventricular septal defect
What does the murmur grade tell you about the severity of the VSD?
Murmur intensity is inversely proportional to the server its of the defect
Small defects create a high pressure - loud murmur
Large defects create a low pressure - quiet murmur
How does a VSD murmur sound?
Systolic murmur
Diagonal murmur - heart on the left hand side and more causally on the right hand side as well
What is the pathophysiology of a VSD?
Blood shunted left to right
Volume overload of the right ventricle
More blood enters the pulmonary circuit
Consequentially volume overload of the left hand side
Resulting in LHS congestive heart failure
How should you guide treatment for a VSD?
Small defects may self resolve with growth
Aortic valve leaflets may prolapse into the defect and aortic regurgitation develops
Pulmonary hypertension may lead to shunt reversal
What is the most common congenital defect in cats?
AV valve dysplasia
What are the common pathological consequences of mitral / tricuspid valve dysplasia?
Volume overload of the effected side of the heart
Atrial fibrillation
Supraventricular tachycardia
What are the 4 components of the tetraology of fallot?
Pulmonic stenosis
Right ventricular hypertrophy
Ventricular septal defect
Dextrapposed aorta
What is the most common congenital heart defect resulting in cynaosis in small animals?
Tetralogy of fallot
