Pulmonary Hypertension - Diagnosis

Diagnosis

Because pulmonary hypertension can be of five major types, a series of tests must be performed to distinguish pulmonary arterial hypertension from venous, hypoxic, thromboembolic, or miscellaneous varieties..

A physical examination is performed to look for typical signs of pulmonary hypertension. These include altered heart sounds, such as a widely split S₂ or second heart sound, a loud P₂ or pulmonic valve closure sound (part of the second heart sound), (para)sternal heave, possible S₃ or third heart sound, and pulmonary regurgitation. Other signs include an elevated jugular venous pressure, peripheral edema (swelling of the ankles and feet), ascites (abdominal swelling due to the accumulation of fluid), hepatojugular reflux, and clubbing.

Further procedures are required to confirm the presence of pulmonary hypertension and exclude other possible diagnoses. These generally include pulmonary function tests; blood tests to exclude HIV, autoimmune diseases, and liver disease; electrocardiography (ECG); arterial blood gas measurements; X-rays of the chest (followed by high-resolution CT scanning if interstitial lung disease is suspected); and ventilation-perfusion or V/Q scanning to exclude chronic thromboembolic pulmonary hypertension. Biopsy of the lung is usually not indicated unless the pulmonary hypertension is thought to be due to an underlying interstitial lung disease; further, lung biopsies are fraught with risks of bleeding due to the high intrapulmonary blood pressure. Clinical improvement is often measured by a "six-minute walk test", i.e. the distance a patient can walk in six minutes. Stability and improvement in this measurement correlate with better survival. Blood BNP level is also being used now to follow progress of patients with pulmonary hypertension.

Diagnosis of PAH requires the presence of pulmonary hypertension. Although pulmonary arterial pressure can be estimated on the basis of echocardiography, pressure measurements with a Swan-Ganz catheter provides the most definite assessment. PAOP and PVR cannot be measured directly with echocardiography. Therefore diagnosis of PAH requires right-sided cardiac catheterization. A Swan-Ganz catheter can also measure the cardiac output, which is far more important in measuring disease severity than the pulmonary arterial pressure.

Normal pulmonary arterial pressure in a person living at sea level has a mean value of 12–16 mm Hg (1600–2100 Pa). Pulmonary hypertension is present when mean pulmonary artery pressure exceeds 25 mm Hg (3300 Pa) at rest or 30 mm Hg (4000 Pa) with exercise.

Mean pulmonary artery pressure (mPAP) should not be confused with systolic pulmonary artery pressure (sPAP), which is often reported on echocardiogram reports. A systolic pressure of 40 mm Hg typically implies a mean pressure of more than 25 mm Hg. Roughly, mPAP = 0.61•sPAP + 2.