Rheumatic Heart Disease Mitral Stenosis and Its Key Physical Sign

Rheumatic heart disease often leads to mitral stenosis, a condition where the mitral valve becomes narrowed and restricts blood flow. One of the most significant and recognizable physical signs of this condition is a low-pitched, rumbling heart murmur heard during the diastolic phase of the heartbeat. This type of murmur is typically localized to the apex of the heart and shows a crescendo pattern, meaning it starts softly and increases in intensity as the heart continues to relax.

Characteristics of the Diastolic Murmur

This murmur is best heard during mid to late diastole and peaks just before the onset of systole. Its unique sound is often described as a rumble, and it is associated with the pressure gradient that develops across the narrowed mitral valve. When the left ventricle relaxes, blood struggles to flow through the restricted valve, causing the distinct sound that physicians listen for during a physical examination.

Factors Affecting the Murmur's Audibility

The murmur becomes more pronounced when a patient is placed in the left lateral decubitus position. Additionally, an increased heart rate or the presence of atrial fibrillation can make the murmur more challenging to identify. In such cases, the timing and rhythm of the heartbeat may obscure the typical crescendo pattern of the murmur.

Understanding the Mechanism Behind the Murmur

The pressure difference across the mitral valve during diastole is the primary reason this murmur occurs. In mild to moderate mitral stenosis, as the pressure gradient increases, the intensity of the murmur also increases proportionally. Therefore, the more severe the narrowing of the valve, the louder and more noticeable the murmur becomes.

Advanced Stages of Mitral Stenosis

However, in the later stages of the disease, when the valve orifice becomes severely restricted, the murmur may actually diminish or disappear altogether. This is due to a reduction in blood flow velocity across the valve, which means there is not enough turbulence to produce a detectable sound. This phenomenon is important for clinicians to understand, as the absence of a murmur does not necessarily indicate an improvement in the patient's condition.