Valvular insufficiency, also termed valvular incompetence, occurs when one or more of the cardiac valves leaks (called “regurgitant flow”) because the valve cusps do not close tightly enough. Inflammation or disease may cause the free edges of the valve cusps to become scarred and constricted, allowing blood to regurgitate back through the valve. As the heart works to overcome the effect of the backflow, blood must be forced through the valve openings and this effort may cause heart enlargement. As a result, the heart must work harder to circulate the normal amount of blood.
Valvular stenosis (ste-nō ́sis; narrowing) is scarring of the valve cusps so that they become rigid or partially fused and cannot open completely. A stenotic valve is narrowed and presents resistance to the flow of blood, so that output from the affected chamber decreases.
Often the affected chamber hypertrophies and dilates—both conditions that may have deleterious consequences. Heart function may become so reduced that the rest of the body cannot receive adequate blood flow. A primary cause of valvular stenosis is rheumatic heart disease.
Rheumatic (roo-mat ́ik) heart disease may follow a streptococcal infection of the throat. It results when antibodies produced to kill the bacteria cross-react with the body’s own connective tissue, thereby initiating an autoimmune disease. All parts of the heart are subject to injury, but the endocardium, the valve cusps, and the left AV valve are typically most affected. Significantly scarred and narrow valves must be surgically repaired or replaced. Patients with a history of rheumatic heart disease must take antibiotics before undergoing dental or medical procedures that are likely to introduce bacteria into the bloodstream.
source : human anatomy
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