|
Acute mitral regurgitation
is disorder in which the heart's mitral valve suddenly
does not close properly, causing blood to leak (back-flow)
into the left atrium (upper heart chamber) when the
left ventricle (lower heart chamber) contracts. Regurgitation
(leaking from insufficient valve closure) is caused
by diseases that weaken or damage the valve or its
supporting structures. Inadequate closure of the mitral
valve causes blood to flow back to the left atrium.
The blood flow to the rest of the body is decreased
as a result and the heart may pump harder to try to
compensate. Acute mitral regurgitation may be the result
of dysfunction or injury to the valve following a heart
attack or infective endocarditis
(infection of the heart valve).
These conditions may rupture
the valve, the papillary muscle or chordae tendineae
(the structures that anchor the valve cusps). A rupture
of these structures results in the valve leaflet prolapsing
or flailing (protruding) into the atrium, leaving an
opening for the backflow of blood.
 In
mitral regurgitation blood flows back through the defective mitral
valve during the contraction of the ventricles (ventricular systole).
Less blood is injected into the aorta and blood supply to the body
is compromised.
|
Symptoms:
- rapid breathing
- shortness of breath that increases when lying flat
(orthopnea); in severe acute mitral
regurgitation, shortness of breath is due the backflow
of blood into the lungs
- chest pain -- unrelated to coronary artery disease
or a heart attack
- cough
- sensation of feeling the heart beat (palpitations)
Note: There may be an abrupt onset of symptoms.
Palpation may show thrill (vibration) over the heart.
A stethoscope may reveal a distinctive murmur in the
heart. However, this murmur may be absent in some
cases of acute mitral regurgitation. If fluid backs
up into the lungs, there may be crackles heard in the lungs. Blood pressure
is usually normal. Billowing of the mitral valve and/or regurgitation of
blood may be seen on: echocardiogram -- an ultrasound examination of the
heart, color flow Doppler examination, transesophageal echocardiogram (TEE),
cardiac catheterization. A chest X-ray may also show fluid in the lungs
or
prominent pulmonary veins. Swan-Ganz (right heart catheterization) pressure
readings will record a marked elevation of left atrial pressure. An ECG
usually shows a
normal sinus rhythm but may show arrhythmias (abnormal heart rhythms) such
as atrial fibrillation. Atrial fibrillation is more common in chronic mitral
regurgitation, however.
Other tests may include a chest MRI scan, radionuclide
scans, or a CT scan of the chest. Emergency surgery may
be necessary if acute regurgitation is severe, usually
resulting from endocarditis (valve infection), heart
attack, or ruptured cordae (one of the supporting
structures of the mitral valve). In emergency situations when blood pressure
cannot be maintained, devices such as the intra-aortic balloon pump (IABP)
reduce backflow by enhancing forward blood flow into the aorta. |
