Lecture 14 - Cardio 5 Flashcards
What is a cardiomyopathy?
Well defined clinico-pathologic entities that are either genetic abnormalities of myocardial contracture or are responsive to substances such as taurine
What are some features of cardiomyopathy?
Features include cardiomegaly (dilation or hypertrophy), mural thrombosis (left ventricle) and fibrosis
How is a diagnosis of cardiomyopathy made?
Diagnosis is based on absence of significant congenital or acquired valvular or vascular abnormality. Presence of dilation or hypertrophy of one or both ventricles (possibly all four) and accompanied in some cases by diffuse fibrosis
What is the name of the condition that is shown below?
Hypertrophic cardiomyopathy (HCM)
Breifly describe the condition that is shown below and state what other clinical findings may be found post-mortem:
Dilated cardiomyopathy - decreased markedly in prevalence since discovery of taurine-deficiency myocardial failure in cats. Omn post mortem all chambers of the heart are enlarged and the ventricles are dilated and flabby with thinned walls
What is the name of the condition that is shown below and what was a likely preceding factor?
Restrictive cardiomyopathy is a result of impaired diastolic ventricular filling due to severe endomyocardial fibrosis. Endomyocarditis was likely a preceding factor in this case
Hypertrophic cardiomyoparthy is very rare in dogs. How does hypertrophic cardiomyopathy normally present?
In young dogs it normally presents as sudden and unexpected anaesthetic deaths or sudden death in otherwise healthy young dogs
What is the most likely cause of cardiomyopathy in dogs and what is the prognosis of it?
Most causes of dilated cardiomyopathy in dogs have a genetic basis. The long term prognosis of this condition is very poor as it is a progressive condition
What is the name of the condition that is shown in the condition below?
Dilated cardiomyopathy - dogs
What is the name of the conditon shown below? Comment on the prevalence of it:
Cardiac neoplasia - primary cardiac neoplasia in all domestic species is quite rare. The exception = haemangiosarcoma in RA of dogs
What are three examples of congenital cardiac diseases that would result in systemic to pulmonary (left to right) shunting?
- Patent ductus arteriosus
- Atrial septal defects
- Ventricular septal defects
What are some congenital cardiac diseases that can result in malformation of semilunar or atrioventricular valves?
- Pulmonary stenosis
- Sub-aortic stenosis
What is a patent ductus arteriosis?
Develops from the sixth left brachial arch of the fetus and diverts a major portion of blood from the aorta to the pulmonary artery
What is an atrial septal defect?
It is failure of the closure of the foramen ovale - an interatrial shunt allowing blood to bypass the lungs of the fetus
Describe the sequelae of events that arises from an atrial septal defect:
- Excessive flow from the left to the right atrium - resultant voluem overload on right ventricle and subsequent elevated central venous pressure
- Results in right ventricular hypertrophy
- Developement of pulmonary hypertension
What is a ventricular septal defect and what are the consequences of it ?
A ventricular septal defect failure is lack of complete developement of intraventricular septum allowing the shunting of blood between them. This results in the left ventricle being enlarged and accompanied by mild sub-endocardial fibrosis following chronic dilation.
Briefly describe the sequelae of events invovled in ventricular septal defects:
- VSD has no deleterious effects on the fetus because left and right ventricular pressures are equal
- The left ventricular ouptut is maintained by an increase in end-diastolic volume and augmenation of contractility by Frank-Starling mechanism (right ventricular pressure then = left ventricular pressure so the right ventricle now has a greater systolic and diastolic load –> pulmonary hypertension. Both ventricles then undergo hypertrophy the left being more obviously eccentric in nature)
- The pulmonary hypertension has the potential to lead to shunt reversal (right –> left, that results in cyanosis and death)
What changes occur in an animal with pulmonic stenosis?
post-stenotic dilation of the pulmonary artery
What is the gross appearance of aortic and sub-aortic stenosis?
The gross appearance of sub-valvular lesions is a small number of fibrous plaques on the endocardial surface of the left ventricular outflow tract. The aortic valves are also frequently involved are are thickened
What are the sequelae to aortic and sub-aortic stenosis?
Increased afterload on the LV and turbulent post stenotic flow –> compensatory concentric hypertrophy of the ventricle and post stenotic dilation of the aorta. Intimal proliferation of collagen and deposition of glycosamines in intramural arteries is common with increased risk of mutlifocal myocardial necrosis and fibrosis
What is arteriosclerosis?
Arteriosclerosis is hardening of the arteries. Chronic arterial change consists of hardening, loss of elasticity and luminal narrowing
What are some causes of arterial mineralisation?
The causes of arterial medial calcification include:
- Vitamin D toxicosis - calcinogenic plant toxicosis
- Renal insufficiency
- Severe debilitation - as seen in cattle with Johne’s disease
