Mitral Regurgitation
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Sonogram of actual 62 year old female patient revealing a functional central mitral regurgitation due to ischemia. The regurgitation can be recognized by the yellow and red “flame” in the upper portion of the echogram above the posterior and anterior mitral leaflets. |
Echogram of the same 62 year old patient with The Cardiosolutions Percu-Pro System implanted in the left ventricular apex and extending up into the mitral valve to provide a sealing surface for the mitral leaflets. The device can be seen as a black, rounded structure between the leaflets preventing the yellow and red “blowback” of mitral regurgitation. |
Mitral Regurgitation results from a partial unloading of the blood volume in the left ventricle back into the upper left atrium upon ventricular contraction (heartbeat). The syndrome is usually divided into two categories, functional and degenerative. Functional MR is caused by ischemia (heart attack) and/or annular dilation in which the annulus, or circular ring of tissue creating the valve orifice, becomes large and unsymmetrical. Degenerative MR consists of structural abnormalities of the valve and associated papillochordal apparatus (e.g. mitral valve prolapse). When MR is present the oxygenated blood is pushed back through the diseased valve because it is not closing properly, and the pressure in the larger left ventricle is greater than that in the smaller left atrium. Fluid dynamics establishes that liquid wants to go from an area of high pressure to an area of low pressure thus we have the resultant backflow if the mitral leaflets are not coapting correctly.
MR imposes an extra load on the heart because the left ventricle has to pump more blood per beat to maintain its normal output throughout the peripheral vascular system. The ventricle must compensate for the volume of blood being pushed back to the atrium due to the valvular inefficiency. This overload on the ventricle results in dilation and eventual failure. Significant MR also results in the enlargement of the left atrium and can incite atrial fibrillation. Atrial fibrillation makes the heart work less effectively and has its own set of complications that include stroke. Pulmonary arterial pressure can increase in response to MR and pulmonary hypertension can occur in varying degrees. The combination of depressed forward cardiac output as well as pulmonary hypertension and concomitant atrial fibrillation is very dangerous, leading to chronic cardiopulmonary decompensation, risk of ischemia, embolization (clotting) and congestive heart failure.
For more information about Mitral Regurgitation please visit these sites:
http://www.nlm.nih.gov/medlineplus/ency/article/000177.htm
http://www.merck.com/mmhe/sec03/ch028/ch028b.html