Differential Diagnosis for Ms Murmur Sound on Exam
- Single most likely diagnosis + Mitral Stenosis: This condition is characterized by the narrowing of the mitral valve opening, which can cause a low-pitched, rumbling murmur best heard at the apex. The murmur is often described as having a "boxcar" shape on phonocardiogram and is typically most prominent during diastole.
- Other Likely diagnoses + Mitral Regurgitation: Although mitral regurgitation typically produces a systolic murmur, severe cases can lead to a mid-diastolic murmur due to increased flow across the mitral valve. This murmur is also best heard at the apex. + Tricuspid Stenosis: This is a less common valvular heart disease that can produce a similar diastolic murmur, best heard at the lower left sternal border. It is often associated with signs of right heart failure. + Aortic Regurgitation: While primarily producing a diastolic murmur best heard at the left sternal border, in some cases, especially with associated mitral stenosis, the murmur can be heard at the apex.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + Endocarditis: Infective endocarditis can cause valvular dysfunction leading to new or changing heart murmurs, including those that might be mistaken for mitral stenosis. It's crucial to consider this diagnosis due to its high morbidity and mortality if left untreated. + Cardiac Tumor (e.g., Left Atrial Myxoma): Although rare, cardiac tumors can obstruct blood flow and produce murmurs similar to those of valvular heart disease. They are a critical diagnosis to consider due to their potential for severe complications.
- Rare diagnoses + Congenital Heart Diseases (e.g., Cor Triatriatum): These are abnormalities in the heart's structure that are present at birth. Some, like cor triatriatum, can produce diastolic murmurs due to obstruction of blood flow. + Rheumatic Heart Disease: While more common in developing countries, rheumatic heart disease can cause valvular lesions, including mitral stenosis, and is a consideration in patients with a history of rheumatic fever.