Question

What are the Disorders of the endocardium and heart valves, write full pathophysiology for each one?

Answer 1

DISORDERS OF ENDOCARDIUM

Cardiopathy ​​​​​​

Dilated cardiomyopathy, the most common type of the disease, is characterized by an enlarged heart with stretching of the ventricle (lower chamber) and atrium (upper chamber). The left ventricle, which pumps oxygenated blood to the body tissues, shows weakness in contraction (systolic dysfunction) and stiffness in expansion and filling (diastolic dysfunction). These dysfunctions lead to fluid retention and eventually heart failure.

In hypertrophic cardiomyopathy, the ventricles are quite small owing to abnormal growth and arrangement of the cardiac muscle fibres. This form of the disease is often hereditary and has been associated with mutations in several different genes, each of which encodes a protein necessary for the formation of sarcomeres, the contractile units of muscle.

Endocarditis

Bacteremia and the presence of endothelial damage are important factors in the pathogenesis of Infective endocarditis.

Vegetations develop at the site of endothelial damage, which is usually located at the lower pressure side of the lesion i.e. in the right ventricle in patients with VSD and on the atrial surface of the mitral valve with mitral insufficiency.

After bacteria adhere to the damaged endothelium, platelets and fibrin are deposited over the organisms, leading to the formation of a vegetation. The organisms trapped within the vegetation are protected from phagocytic cells and other host defense mechanisms.

Myocardial fibrosis

When cardiac damage and stress occur, various substances cause fibroblasts to become activated and transdifferentiate into my fibroblasts. The myofibroblasts increase the production of proteins that are deposited in the extracellular matrix.Collagen I, which accounts for about 80 % of the collagen in the myocardium, makes the myocardium stiffer and increases most in myocardial fibrosis. Cross-linking makes the collagen matrix stiffer and more difficult to break down with proteinases. Fibrosis occurs as a result of net collagen production. Fibrosis restricts the supply of oxygen and nourishment to the myocardium. Myocardial fibrosis causes electrical and structural changes that predispose patients to arrhythmias, heart failure and ischaemia.

DISORDERS OF HEART VALVES

Valvular heart diseases are cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.

Valve involved	Stenotic disease	Insufficiency/ Regurgitation disease
Aortic valve	Aortic valve stenosis	Aortic Insufficiency /Regurgitation
Mitral valve	Mitral valve stenosis	Mitral insufficiency /Regurgitation
Tricuspid valve	Tricuspid valve stenosis	Tricuspid insufficiency /Regurgitation
Pulmonary valve	Pulmonary valve stenosis	Pulmonary insufficiency /Regurgitation

Aortic and Mitral Valve disorders

Aortic and mitral valve disease are termed left heart.

The Aortic valve stenosis ischaracterized by a thickening of the valvular leaflets that reduce the ability of blood to be ejected from the left ventricle into the aorta. Stenosis is result of valvular calcification but can be the result of a congenitally malformed bicuspid aortic valve. This defect is characterized by the presence of only two valve leaflets. It may occur in isolation or in concert with other cardiac anomalies.

Aortic insufficiency or regurgitation, is characterized by an inability of the valve leaflets to appropriately close at systolic end, thus allowing blood to flow inappropriately backwards into the left ventricle. Causes of aortic insufficiency in the majority of cases are unknown, or idiopathic. It may be the result of connective tissue or immune disorders, such as Marfan syndrome or systemic lupus erythematosus, respectively. Processes that lead to aortic insufficiency usually involve dilation of the valve annulus, thus displacing the valve leaflets, which are anchored in the annulus.

In normal cardiac physiology, the mitral valve opens during left ventricular diastole, to allow blood to flow from the left atrium to the left ventricle.In mitral valve stenosis, a normal mitral valve will not impede the flow of blood from the left atrium to the left ventricle during (ventricular) diastole, and the pressures in the left atrium and the left ventricle during ventricular diastole will be equal. The result is that the left ventricle gets filled with blood during early ventricular diastole, with only a small portion of extra blood contributed by contraction of the left atrium (the "atrial kick") during late ventricular.

Mitral insufficiency can be caused by dilation of the left heart, often a consequence of heart failure. In these cases the left ventricle of the heart becomes enlarged and causes displacement of the attached papillary muscles, which control the mitral valve.

Tricuspid and pulmonary valve disorders

Pulmonary and tricuspid valve diseases are right heart.

The pathophysiology of pulmonary valve stenosis consists of the valve leaflets becoming too thick (therefore not separate one from another), which can cause high pulmonary pressure, and pulmonary hypertension. This however, does not mean the cause is always congenital.

The left ventricle can be changed physically, these changes are a direct result of right ventricular hypertrophy. Once the obstruction is subdued, it (the left ventricle) can return to normal.

The Pulmonary valve insufficiency pathophysiology is due to diastolic pressure variations between the pulmonary artery and right ventricle, differences are often very small, but increase regurgitation. An elevation in pulmonary insufficiency due to elevated intrathoracic pressure is relevant in ventilated patients (having acute restrictive right ventricular physiology). The reasons for changes in stiffness of the right ventricle's walls are not well understood, but such stiffness is thought to increase with hypertrophy of the ventricle.

Tricuspid valve Stenosis is highly uncommon and typically the result of rheumatic disease. It may also be the result of congenital abnormalities, carcinoid syndrome, obstructive right atrial tumors (typically lipomas or myxomas), or hypereosinophilic syndromes.

The pathophysiology of tricuspid insufficiency it involves the expansion of the tricuspid annulus (fibrous rings of heart). Tricuspid insufficiency is linked to geometric changes of the tricuspid annulus (decreased tricuspid annular release). The leaflets shape are normal but prevented from normal working mechanism due to a distortion of spatial relationships of leaflets and chords. It is also contemplated that the process via which tricuspid regurgitation emerges, is a decrease of contraction of the myocardium around the annulus.