<unk> is blood flow in the opposite direction from normal, as the backward flowing of blood into the heart or between heart chambers. It is the circulatory equivalent of backflow in engineered systems. It is sometimes called reflux.<unk> in or near the heart is often caused by valvular insufficiency (insufficient function, with incomplete closure, of the heart valves); for example, aortic valve insufficiency causes<unk> through that valve, called aortic<unk>  and the terms aortic insufficiency and aortic<unk> are so closely linked as usually to be treated as metonymically interchangeable. The various types of heart valve<unk> via insufficiency are as follows: # Aortic<unk>  the backflow of blood from the aorta into the left ventricle, owing to insufficiency of the aortic semilunar valve; it may be chronic or acute. # Mitral<unk>  the backflow of blood from the left ventricle into the left atrium, owing to insufficiency of the mitral valve; it may be acute or chronic, and is usually due to mitral valve prolapse, rheumatic heart disease, or a complication of cardiac dilatation. See also Mitral<unk>  # Pulmonic<unk>  the backflow of blood from the pulmonary artery into the right ventricle, owing to insufficiency of the pulmonic semilunar valve. # Tricuspid<unk>  the backflow of blood from the right ventricle into the right atrium, owing to imperfect functioning (insufficiency) of the tricuspid valve.
Regurgitation 
Cavitation 
Proarrhythmia
Exercise intolerance
Allostasis
Venospasm
Cyclospasm
Atopy