Background: Prognostic evaluation of patients with primary pulmonary hypertension (PPH) requires right heart catheterisation. The development of accurate non-invasive methods for monitoring these patients remains an important task. Cyclic guanosine monophosphate (cGMP) is an indicator of the action of natriuretic peptides and nitric oxide on target cells. Plasma and urinary cGMP concentrations are raised in patients with congestive heart failure in whom they correlate closely with haemodynamic parameters and disease severity. The aim of the present study was to determine whether the urinary concentration of cGMP could be used as a non-invasive marker of haemodynamic impairment in patients with severe PPH.
Methods: Urinary cGMP concentrations were measured in 19 consecutive patients with PPH, seven with acute asthma, and 30 normal healthy controls.
Results: Patients with PPH had higher urinary cGMP concentrations than asthmatic patients or normal healthy controls (p = 0.001). Urinary cGMP concentrations were higher in patients with severe haemodynamic impairment--that is, those with a cardiac index (CI) of < or = 2 l/min/m2 (p = 0.002)--and urinary cGMP concentrations were inversely correlated with CI (r = -0.69, p = 0.002) and venous oxygen saturation (r = -0.65, p = 0.003).
Conclusion: Urinary cGMP concentrations may represent a non-invasive indicator of the haemodynamic status of patients with severe PPH.