You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Description

The mitral valve lies between the left atrium and left ventricle chambers of the heart. It is one of the so-called Atrioventricular valves. It consists of a fibrous ring at the junction between the atrium and the ventricle and its cusps are indistinct. It is a one-way valve that does not allow blood to pass back into the atrium during the systolic phase of the cardiac cycle , when the ventricular muscle contracts to force oxygenated blood out into the aorta - the body's largest artery. Strong fibrous chordae tendineae attach the valve to large papillary muscles. The pressure of blood leaving through the aorta is about 4 times as great as the pressure of blood leaving the heart to pass into the pulmonary artery.

If the valve becomes damaged - such as occurs with chronic valvular degeneration (or endocardiosis) the blood leaks back (called regurgitation) into the atrium and causes an abnormal heart sound (murmur). This can be heard loudest over the 5^th intercostal space, about one-third of the way up from the sternum on the left-hand side of the chest wall. On X-rays the affected atrium and ventricle may both appear enlarged and colour flow Doppler imaging clearly shows blood flowing through the valve in the wrong direction.

Last updated : October 2013