Review Question - QID 104254

This patient with limited routine medical care in childhood that now presents with palpitations, an electrocardiogram demonstrating atrial fibrillation, and a rumbling diastolic murmur likely has mitral stenosis. The most appropriate first step in evaluating this patient’s condition is a transthoracic echocardiogram.

Mitral stenosis can occur secondary to rheumatic heart disease. Patients typically have a history of rheumatic fever in childhood, though this may not always be explicitly stated. Rheumatic fever and subsequent rheumatic heart disease are rare in the United States due to the wide availability of antibiotics. Rheumatic disease remains common in developing nations. The murmur of mitral stenosis occurs during diastole, often following an opening snap. It has a rumbling quality that is usually loudest at the start of diastole. If the degree of stenosis is mild, the murmur may be difficult to auscultate. The murmur can be enhanced by having the patient lie on his left side and using the bell of the stethoscope or by having the patient engage in mild exercise such as walking. Increased pressure in the left atrium as a result of mitral valve stenosis can lead to dilation of the left atrium. As the left atrium expands, patients often develop atrial fibrillation. In rare cases, the dilated left atrium may lead to compression of the esophagus and symptoms of dysphagia. Transthoracic echocardiography is used to confirm the diagnosis, determine the valve area and ventricular function, and assess whether the patient is a good candidate for balloon valvotomy.

Shipton and Wahba discuss management of mitral stenosis. For those who are asymptomatic, annual visits to a physician, chest radiograph, and ECG are recommended. When symptoms, such as dyspnea on exertion develop, diuretics may be helpful. Potential interventions include balloon valvotomy, mitral valve reconstruction and replacement.

Figure A shows an electrocardiogram demonstrating atrial fibrillation. Note the narrow QRS complex and the irregularly irregular rhythm with the lack of discernible P waves.

Incorrect answers:
Answer 1: Anti-streptolysin O titers are sometimes used in the diagnosis of acute rheumatic fever. This patient's condition is a result of chronic rheumatic heart disease, which follows an episode of untreated acute rheumatic fever.

Answer 2: Cardiac MRI is sometimes utilized to further characterize structural heart diseases. It is an expensive and time consuming test. Transthoracic echocardiogram is the most appropriate first step in diagnosis.

Answer 3: Observation would not be appropriate. Observation may be appropriate for certain benign murmurs in childhood, such as a Still murmur. Diastolic murmurs are always pathologic and necessitate further evaluation.

Answer 4: Transesophageal echocardiogram is sometimes utilized to evaluate valvular pathology. Transthoracic echocardiogram is sufficient in most cases, and does not require sedation and carry the risks associated with transesophageal echocardiography.

Bullet Summary:
For patients with suspected mitral stenosis, the most appropriate first step in evaluation is a transthoracic echocardiogram.