Study objectives: We sought to compare catheter studies
using a right ventricular ejection fraction (REF) catheter together
with echocardiography and MRI in patients with pulmonary
Patients and methods: We compared
hemodynamic findings, echocardiography, and MRI studies in 16 patients
with pulmonary hypertension. Six healthy volunteers 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 underestimated the
REF and overestimated right ventricular volumes in patients with
pulmonary hypertension. REF, end-systolic and end-diastolic right
ventricular volumes, and right ventricular muscle mass, as determined
by MRI, were almost identical in patients with preserved cardiac
function and those with low-output failure. The only factor that was
different in both groups was the severity of tricuspid
Conclusion: Right ventricular
dimensions and muscle mass do not differ in patients with pulmonary
hypertension who have low cardiac output and those who do not.
According to our results, the major determinant of cardiac output in
these patients appears to be the severity of tricuspid regurgitation.
The REF catheter provides invalid data on right ventricular dimensions
in patients with pulmonary hypertension.