L6: Pathology of Congenital Heart Diseases

What is patent ductus arteriosus (PDA)?

most common defect of dogs where the ductus arteriosus does not close after birth. left cardiac chamber → aorta → patent ductus → pulmonary artery → overcirculation to lungs → pulmonary hypertension and increase preload to left ventricle

What is patent foramen ovale?

foramen does not close into fossa (secondary) or primary being its located low in the septum; left atrium → septal defect → right atrium → volume overload → right ventricular dilation

What is a (inter)ventricular septal defect?

common in ruminants with failure to completely develop the interventricular septum (usually in upper portion); shunting of blood between ventricles (left to right) → volume overload

What is teralogy of fallot?

1. pulmonic stenosis

2. ventricular septal defect located high in septum

3. dextroposition (overriding) of aorta

4. hypertrophy of right ventricular myocardium (secondary)

What is stenosis of the great vessels (pulmonic/aortic/subaortic)?

common in bulldogs and beagles where valvular lesions include formation of circumferential band of fibrous or muscular tissue beneath the valve (subvalvular stenosis) or malformation of the valve (valvular stenosis)

What is valvular dysplasia (endocardial cushion defects)?

tricuspid and mitral valve displasias; dysplastic malformations in the AV valves → valvular insufficiency → volume overload with resultant atrial dilation

What is persistent right aortic arch?

results in megaesophagus leading to aspiration pneumonia; ligamentum arteriosum forms a vascular ring over the esophagus and trachea

What are ectopia cordis?

congenital development of the heart at an abnormal site outside of the thoracic cavity

What are the congenital defects seen in ruminants? Such as cattle, sheep, and goats.

valvular hematomas (hemocyst) and ventricular septal defect

What are the congenital defects seen in dogs?

patent ductus arteriosus, pulmonic stenosis (bulldogs), persistent right aortic arch

What kind of hypertrophy does PDA cause?

eccentric hypertrophy due to volume overload to left ventricle and concentric hypertrophy due to pressure overload of the right ventricle

What is another term for patent foramen ovale?

atrial septal defect (primary)

What kind of hypertrophy does atrial septal defect/patent foramen ovale cause?

eccentric hypertrophy of right ventricle

What kind of hypertrophy does an (inter)ventricular septal defect cause?

eccentric hypertrophy of both ventricles due to shunting

What kind of hypertrophy does pulmonic stenosis cause?

increase afterload placed on right ventricle: concentric right ventricular hypertrophy

What kind of hypertrophy does aortic/subaortic stenosis cause?

increased afterload on the left ventricle and turbulent poststenotic flow: compensatory concentric left ventricular hypertrophy

What are “Jet Lesions”?

force of blood ejected though stenotic lesion created this in aorta

What kind of hypertrophy does valvular dysplasia (endocardial cushion defects) cause?

eccentric ventricular hypertrophy

What is the difference between persistent right aortic arch cause megaesophagus verses myasthenia gravis causing it?

persistent right aortic arch only causes it to the proximal portion

What is congenital hematomas (hemocysts)?

cysts in margins of the AV valves especially in calves

What is a cardiac anomaly found in cats?

endocardial fibroelastosis, prominent white thickened endocardium from hypoxia

What are epithelial inclusions?

miscellaneous cardiac anomaly found as an incidental finding in myocardium of bovine, seen as areas of discoloration or sponginess