A diagnosis of PH can only be made with a positive right heart catheterisation finding. Measurement of the pulmonary vascular resistance (PVR), cardiac index (CI) and mean right atrial pressure (mRAP) allows statements to be made regarding the severity and hence the prognosis for the patient. On the basis of current data, the CI, mRAP and mPAP parameters are independent predictors of survival, although it must be borne in mind that mPAP also falls with decreased right ventricular function.

A complete right heart catheter examination should include measurement of the pulmonary capillary wedge pressure (PCWP) using a balloon catheter in various sections of the pulmonary vascular system. This permits differentiation between pre- and post-capillary PH. If optimal measurement of the PCWP is not possible or is in doubt, left ventricular end-diastolic pressure (LVEDP) may also be determined. A primary measurement of LVEDP is also recommended in patients in whom there is a high probability of a left ventricular cause of the symptoms (e.g. orthopnoea).

A test of pulmonary vasoreactivity is recommended in principle for all patients with documented pulmonary hypertension. The acute response to vasodilators correlates well with the underlying vascular morphology and thus constitutes a good prognostic parameter. Those patients in whom the mean pulmonary arterial pressure (mPAP) drops by at least 10 mmHg below an absolute value of 40 mmHg are described as responders. Cardiac output should increase or at least remain unchanged at the same time. The vasoreactivity test should only be performed using substances with a short half-life. Test substances recommended by the European Society of Cardiology (ESC) are epoprostenol, adenosine and nitric oxide (NO). Approximately 10% of all adults with idiopathic PAH are haemodynamic responders. High-dose calcium channel blocker therapy is indicated for these patients. Genuine responders have an excellent prognosis with a 5-year survival rate of almost 95% [27].