Family history may reveal relatives with PH, given the genetic predisposition to development of Group 1 PH. Physical exam findings include a prominent pulmonic valve closure during the second heart sound, a palpable left parasternal heave, and a tricuspid regurgitation murmur.
Electrocardiogram (ECG) and chest X-ray (CXR) are not sufficiently sensitive or specific to diagnose PH but may provide initial supporting evidence that prompts further testing. Signs of right ventricular hypertrophy and right atrial enlargement may be present on ECG. The CXR may show pruning (prominent hilar vasculature with reduced vasculature peripherally) and right ventricular hypertrophy, as evidenced by shrinking of the retrosternal window on lateral CXR. An unremarkable ECG or normal CXR does not rule out PH.
Echocardiography: TTE allows estimation of pulmonary artery systolic pressure (PASP) via measurement of tricuspid regurgitation jet velocity and estimation of right atrial pressure. Although results of TTE do correlate with measurements from right heart catheterization (RHC), underestimation and overestimation commonly occur. PASP thresholds for diagnosing or ruling out PH cannot thus be defined easily. An elevated PASP less than 36 mmHg, tricuspid regurgitation velocity <2.8 m/s, and no additional echocardiographic variables suggestive of PH may indicate that PH is unlikely, based on arbitrary criteria from one clinical practice guideline.16
The guideline suggested that tricuspid regurgitation velocity >3.4 m/s or estimated PASP >50 mmHg indicated that PH was likely. Other echocardiographic variables that may suggest the presence of PH include right ventricular enlargement or intraventricular septal flattening. Finally, TTE should also be used to assess for possible causes of PH, such as left heart disease or cardiac shunts.
Further evaluation: Following identification of PH via TTE, further testing can confirm the diagnosis, determine the etiology of the PH, and allow appropriate treatment (see Table 2). Much of this evaluation may occur after hospital discharge and, in cases of unexplained PH, referral to a pulmonologist for further evaluation and management is appropriate. Depending on patient stability, test availability, and patient ability to follow up, some testing may be reasonable during the inpatient stay.
(Click for larger image.)Table 2. Suggested steps in evaluating pulmonary hypertension (PH).17,18
Patients should undergo a stepwise series of testing that initially may be guided by clinical suspicion for underlying conditions.15-19 Polysomnography can identify sleep-disordered breathing, and pulmonary function tests and high-resolution chest CT can assess for chronic pulmonary diseases. Patients with groups 2 and 3 PH, whose PH can be explained by left heart disease or lung disease, do not necessarily require RHC or extensive evaluation for other etiologies of PH.2,17 These patients may be monitored while their underlying conditions are managed.
Patients with worsening clinical course or PH that is “out of proportion” to their lung disease or heart disease, however, do require further evaluation, including RHC. “Out of proportion” has not been consistently defined but generally refers to severe PH observed in patients with mild left heart or lung disease.18 More precise terminology and criteria to define patients with out of proportion PH have been proposed.14
Ventilation-perfusion scanning is required in all cases of PH of unknown etiology to evaluate for CTEPH (Group 4 PH). CT angiography, while appropriate to use in testing for acute pulmonary embolism, is not sufficiently sensitive to evaluate for CTEPH. Tests for liver function, HIV, and connective tissue disease may identify conditions associated with Group 1 PH. Ultimately, RHC is required to confirm the diagnosis of PH, given the shortcomings of TTE. A vasodilator study during RHC allows identification of candidates for advanced therapies, such as patients with Group 1 PH.