Mitral Valve Disorders

The mitral valve sits between the two left-sided chambers, and when it fails — whether it won't open or won't close — blood backs up into the lungs before the patient ever notices ankle swelling.

Mitral stenosis and mitral regurgitation are the two primary mitral valve disorders, and they produce different hemodynamic problems with overlapping but distinct presentations. In mitral stenosis, the valve leaflets thicken and fuse (often from a history of rheumatic fever), restricting blood flow from the left atrium to the left ventricle. The left atrium dilates under chronic pressure, predisposing the patient to atrial fibrillation and thrombus formation. Pulmonary congestion develops because blood backs up behind the narrowed valve — expect dyspnea on exertion, orthopnea, and a low-pitched diastolic rumble heard best at the apex with the bell. In mitral regurgitation (insufficiency), the valve fails to close completely, allowing blood to flow backward into the left atrium during systole. This produces a high-pitched blowing holosystolic (pansystolic) murmur at the apex radiating to the left axilla. Over time, both the left atrium and left ventricle dilate to handle the volume overload. Fatigue, palpitations, and progressive exertional dyspnea are hallmarks of both disorders. Atrial fibrillation is common in both, but especially in stenosis due to atrial stretch. Nursing assessment priorities include auscultating heart sounds in the correct position (left lateral decubitus for stenosis), monitoring for signs of pulmonary edema, and tracking rhythm changes.

Key Distinctions

Stenosis murmur is diastolic (valve should be open but won't); regurgitation murmur is systolic (valve should be closed but won't). Students confuse this — remember the murmur timing reflects when the valve is failing its job. Don't attribute peripheral edema and JVD primarily to mitral disease; those are right-sided signs. Mitral disorders cause pulmonary congestion first.

Clinical Pearl

Stenosis = stuck shut = diastolic rumble. Regurgitation = leaks open = systolic blow. Match the murmur to the phase when the valve should be doing the opposite.