The mitral valve connects left atrium to the left ventricle. It has two cusps that, when open, lets blood flow in one direction, from the left atrium into the left ventricle. A murmur is a abnormal sound made by blood that is flowing irregularly, or turbulently in the heart or arteries. It may be caused by a narrowed vessel or valve, a leaking valve, or too much blood flow through a normal vessel. The presence of a murmur may not mean a significant heart problems, but usually requires further evaluation.
Systolic murmurs occur when the heart is contracting.
Diastolic murmurs occur when the heart is relaxing. Continuous murmurs usually indicate abnormal communications between arteries and veins or between the aorta and other parts of the heart. Most myocardial infarctions occur in the left ventricle and cause sharp pain in the chest, which can spread to the arms and throat. Other complications include ventricular fibrillation , heart failure , embolisms , mitral incompetence , and shock. The myocardium is the muscular middle layer of the heart, responsible for making the heart contract.