To investigate right ventricular function, 24 patients with arterial hypertension and five normotensive controls underwent equilibrium radionuclide ventriculography with simultaneous right heart catheterization. In normal subjects, left ventricular ejection fraction was 57 +/- 2% at rest and 71 +/- 5% on effort, and right ventricular ejection fraction (RVEF) averaged 51 +/- 5% at rest and 65 +/- 2% during exercise. Pulmonary vessel resistance (PVR) was 56 +/- 37 dyn.s.cm-5 at rest and 46 +/- 10 dyn.s.cm-5 on effort. Hypertensive patients were divided into three groups according to their left ventricular function: group 1 (n = 10) had normal left ventricular ejection fraction (LVEF) at rest and on effort (57 +/- 9%; 65 +/- 6%), in this group, right ventricular systolic reserve was reduced (RVEF 52 +/- 7% at rest, ns; RVEF 57 +/- 7% on effort, P less than 0.01 compared to controls). Pulmonary vessel resistance during exercise averaged 78 +/- 24 dyn.s.cm-5, which was significantly higher compared to controls (P less than 0.01). In group 2, left ventricular contractions were normal at rest (60 +/- 6%, ns) but deteriorated during exercise to 56 +/- 8% (P less than 0.001, compared to controls). These patients also showed a lack of right ventricular augmentation at ejection fraction (54 +/- 8% at rest, ns; 56 +/- 8% under exercise, P less than 0.05). PVR was significantly enhanced during exercise (88 +/- 40 dyn.s.cm-5, P less than 0.05 compared to controls).(ABSTRACT TRUNCATED AT 250 WORDS)