Valvular Heart Disease

Valvular heart disease refers to damage or defects involving one or more heart valves, and can be either stenosis, or narrowing of the valvular opening; or regurgitation, also called insufficiency or incompetence, or failure of the valve to adequately close.

Alright so, valvular heart disease is caused by damage or defects involving one or more heart valves. One cause of valvular heart disease is rheumatic fever, which is an inflammatory condition that typically occurs after a strep throat infection from Streptococcus pyogenes, also referred to as group A beta-hemolytic streptococcus. Other important causes include congenital defects, infective endocarditis, atherosclerosis, myocardial infarction, as well as autoimmune diseases like rheumatoid arthritis or systemic lupus erythematosus; or connective tissue disorders, like Marfan syndrome.

Now, the heart valves control blood flow through the heart. The two atrioventricular, or AV, valves include the tricuspid valve that separates the right atrium from the right ventricle and the mitral valve, which separates the left atrium from the left ventricle. The two semilunar valves are the pulmonary valve that separates the right ventricle from the pulmonary artery and the aortic valve that separates the left ventricle from the aorta. The type of valvular heart disease depends on the affected valve and the type of defect.

So, let’s start with mitral stenosis, which is where the valve leaflets either fuse together or stiffen, impairing the valve opening, making it harder for blood to flow from the left atrium to the left ventricle. As a result, the pressure in the left atrium increases, which compensates by undergoing hypertrophy and dilation to accommodate the extra blood.

Then there's mitral valve regurgitation, where the valve fails to close completely during systole; or sometimes, the leaflets bulge back, or prolapse, into the left atrium. Either way, blood flows back from the left ventricle into the left atrium. As with mitral stenosis, left atrial pressure increases, resulting in hypertrophy and dilation. Now, eventually blood will start backing up from the left atrium into the lungs, resulting in pulmonary edema, which can make it harder for the right ventricle to pump blood into the pulmonary artery. Over time, the right ventricle can also undergo hypertrophy, and ultimately fail, which is known as right-sided heart failure.

Next up is aortic stenosis, where the leaflets of the aortic valve become stiff, so they can’t open fully, making it harder for blood to flow from the left ventricle into the aorta. To compensate, the left ventricle undergoes hypertrophy and dilation to accommodate the extra blood.

In aortic regurgitation, the valve doesn’t close properly during diastole, so blood leaks from the aorta, back into the left ventricle. To compensate, the left ventricle undergoes hypertrophy and dilation; but eventually, the left ventricle begins to fail, and blood starts to back up into the left atrium and into pulmonary circulation, causing pulmonary edema.