Evaluation of right ventricular performance with a right ventricular ejection fraction thermodilution catheter and MRI in patients with pulmonary hypertension

Study objectives: We sought to compare catheter studies using a right ventr icular ejection fraction (REF) catheter together with echocardiography and MRI in patients with pulmonary hypertension. Patients and methods: We compared hemodynamic findings, echocardiography, a nd MRI studies in 16 patients with pulmonary hypertension. Six healthy volu nteers served as control subjects for the MRI studies. Results: MRI imaging provided accurate assessment of cardiac output in all but two patients. As compared with MRI, the REF catheter constantly underes timated the REF and overestimated right ventricular volumes in patients wit h pulmonary hypertension. REF, end-systolic and end-diastolic right ventric ular volumes, and right ventricular muscle mass, as determined by MRI, were almost identical in patients with preserved cardiac function and those wit h low-output failure. The only factor that was different in both groups was the severity of tricuspid regurgitation. Conclusion: Right ventricular dimensions and muscle mass do not differ in p atients with pulmonary hypertension who have low cardiac output and those w ho do not. According to our results, the major determinant of cardiac outpu t in these patients appears to be the severity of tricuspid regurgitation. The REF catheter provides invalid data on right ventricular dimensions in p atients with pulmonary hypertension.