A 35-year-old woman is evaluated for a 4-month history of exertional dyspnea and a 1-week history of chest pressure. She has no sputum production, cough, or wheezes. She has never smoked.
On physical examination, vital signs are normal. Oxygen saturation is 91% breathing ambient air. Cardiopulmonary examination reveals a widened split S2 with a prominent pulmonic component and neck vein distention. Lungs are clear to auscultation.
Laboratory studies, including complete blood count and comprehensive metabolic profile, are normal.
Electrocardiogram is normal.
Chest radiograph shows clear lung fields and prominent hilae.
Which of the following is the most appropriate initial test?
A. High resolution CT of the chest
B. Pulmonary function testing
C. Transthoracic echocardiogram
D. Ventilation-perfusion (V̇/Q̇) scan
MKSAP Answer and Critique
The correct answer is C. Transthoracic echocardiogram. This content is available to MKSAP 18 subscribers as Question 23 in the Pulmonology and Critical Care Medicine section. More information about MKSAP is available online.
The next most appropriate initial test is transthoracic echocardiography. Pulmonary hypertension is easily overlooked because early signs and symptoms, such as exertional dyspnea and fatigue, are nonspecific. As the disorder progresses, right ventricular impairment may be heralded by exertional chest pain, syncope, and peripheral edema. Findings on physical examination depend on the severity of disease. The cardiovascular examination may show jugular venous distention, a prominent jugular venous a wave, parasternal heave, a widened split S2 with a prominent pulmonic component, or murmurs of tricuspid regurgitation as the right ventricle dilates.
Transthoracic echocardiography is a useful initial tool in the evaluation of suspected pulmonary hypertension as it allows an estimation of pulmonary artery pressures and right heart function as well as an assessment of the left heart. Because echocardiography may underestimate true pulmonary artery pressures, the evaluation should not end with an unrevealing echocardiogram if the index of suspicion for pulmonary hypertension is high. In such cases, right heart catheterization may be confirmatory. Once pulmonary hypertension is confirmed, further testing, guided by clinical history, helps determine identifiable causes. Left heart catheterization can assess coronary flow and left ventricular function. Diagnostic tests for respiratory diseases might include pulmonary function tests, chest imaging, ventilation-perfusion (V̇/Q̇) scanning, and overnight pulse oximetry.
High-resolution CT scanning of the chest allows a detailed assessment of the lung parenchyma and is useful in the evaluation of suspected interstitial lung diseases, but is unlikely to be helpful as an initial test in a patient with an unremarkable lung examination and clear lung fields on chest radiograph.
Pulmonary function testing is an important diagnostic test for suspected airways disease such as asthma, COPD, or interstitial lung disease. However, this patient has no symptoms or physical examination findings indicative of either obstructive or restrictive disease. In the patient with isolated pulmonary hypertension, pulmonary function tests demonstrate a reduction in diffusing capacity, which is a nonspecific finding.
V̇/Q̇ scanning is the diagnostic test of choice for suspected chronic thromboembolic pulmonary hypertension (CTEPH). Although CTEPH hasn't yet been excluded in this patient, V̇/Q̇ scanning would typically be performed after transthoracic echocardiography to first establish the presence of pulmonary hypertension.
- Transthoracic echocardiography can estimate pulmonary artery pressures and is the preferred initial test if pulmonary hypertension is suspected.