MKSAP Quiz: fatigue and exertional dyspnea
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A 31-year-old woman is evaluated for fatigue and exertional dyspnea. She reports no chest pain, palpitations, or syncope. She has no symptoms of collagen vascular disease. She has had no recent fevers, sick contacts, or weight gain. She smokes one pack of cigarettes per day and denies illicit drug use. Her family history is significant for a mother with mitral valve prolapse. She is on no medications and has never taken oral contraceptives.
On physical examination, temperature is normal, blood pressure is 122/60 mm Hg, and pulse is 80/min. BMI is 23. Cardiac examination reveals a point of maximal impulse that is undisplaced. A grade 2/6 lower left parasternal systolic murmur is heard that increases with inspiration but does not radiate. There are prominent jugular venous pulsations. There is 1+ pedal edema.
Leukocyte count is normal. An electrocardiogram shows evidence of right ventricular hypertrophy. A chest radiograph shows enlarged pulmonary arteries, right atrium, and right ventricle. A transthoracic echocardiogram demonstrates normal left ventricular size and function. The right ventricle is moderately enlarged. Aortic and mitral valve function are normal. There is moderate tricuspid regurgitation. No evidence of an interatrial shunt is seen by color Doppler imaging or following agitated saline contrast. Pulmonary pressure estimates are 60 to 65 mm Hg.
Which of the following is an appropriate next diagnostic test?
A. Cardiac magnetic resonance imaging
B. Stress echocardiogram
C. Transesophageal echocardiogram
D. Ventilation-perfusion lung scan
MKSAP Answer and Critique
The correct answer is D) Ventilation-perfusion lung scan. This item is available to MKSAP 15 subscribers as item 88 in the Cardiology section.
The most appropriate diagnostic test for this patient is ventilation-perfusion lung scanning. This patient has tricuspid regurgitation and significant pulmonary hypertension with evidence of pressure overload on the right ventricle. Pulmonary hypertension with right ventricular enlargement and tricuspid valve annular dilation can lead to significant regurgitation of an otherwise normal tricuspid valve. Pulmonary hypertension may occur when abnormalities in left heart valvular or myocardial function (systolic or diastolic) cause pulmonary venous hypertension. Additional causes of pulmonary hypertension include chronic hypoxic pulmonary disorders (such as chronic obstructive pulmonary disease, interstitial lung disease, or sleep apnea) and chronic thromboembolic disease. Pulmonary hypertension may occur in association with anorectic drug use, HIV infection, chronic liver disease, or collagen vascular disease. In the absence of identifiable risk factors, pulmonary hypertension may be idiopathic. A diagnosis of idiopathic primary pulmonary arterial hypertension requires exclusion of secondary and associated causes of pulmonary hypertension. Additionally, right heart catheterization is needed to confirm the presence of pulmonary hypertension, exclude elevated left-sided filling pressures, and demonstrate elevated pulmonary vascular resistance.
Numerous diagnostic tests may be used to evaluate a patient with suspected pulmonary hypertension. Pulmonary function tests are needed to identify and characterize underlying lung disease. Ventilation-perfusion scanning is used to evaluate patients for chronic thromboembolic disease. A normal scan has greater than 90% sensitivity in excluding chronic thromboembolic disease and a similarly high specificity. Although helpful in the evaluation of acute pulmonary embolism, CT angiography is not known to be sufficiently sensitive for detection of chronic thromboembolism. Blood tests are performed to evaluate potential liver disease, HIV infection, or collagen vascular disease. A right heart catheterization confirms the presence of pulmonary hypertension and allows for calculation of pulmonary vascular resistance. Some patients require left heart catheterization as well.
Cardiac magnetic resonance (CMR) imaging is useful when evaluating primary myocardial abnormalities (such as an infiltrative disease), evaluating ventricular volumes, or assessing three-dimensional imaging of congenital heart disease. In this patient, transthoracic images do not suggest congenital heart disease. CMR imaging would not be the next imaging study of choice.
Exertional dyspnea may be an angina equivalent and stress echocardiography could be considered. However, the patient's age, relative paucity of cardiovascular risk factors, and abnormal transthoracic echocardiogram findings (right ventricular enlargement and pulmonary hypertension) argue against an ischemic cause for her symptoms. A ventilation-perfusion lung scan is the appropriate next diagnostic test.
Transesophageal echocardiography to evaluate for tricuspid valve vegetations would be indicated if there were a strong clinical suspicion for endocarditis. This patient's clinical presentation, with an absence of corroborating history, fever, or an elevated leukocyte count, does not suggest endocarditis.
Key Point
- Pulmonary hypertension may lead to right ventricular enlargement, tricuspid valve annular dilation, and regurgitation in an otherwise normal tricuspid valve.