To evaluate the potential occurrence of right ventricular infarction, 53 patients with acute inferior transmural myocardial infarction were studied within 36 hours of symptoms by right heart catheterization, equilibrium radionuclide angiography and two-dimensional echocardiography. Technetium-99m pyrophosphate myocardial scintigraphy was performed 3 days after the onset of symptoms. The hemodynamic standard for right ventricular infarction was defined as both a right atrial pressure of 10 mm Hg or more and a right atrial/pulmonary artery wedge pressure ratio of 0.8 or more. Eight (15%) of the 53 patients had hemodynamic measurements at rest characteristic of right ventricular infarction, and 6 (11%) additional patients met these criteria after volume loading (p < 0.05).
Nineteen (37%) of the 51 patients who had radionuclide angiography had right ventricular dysfunction manifested by both a reduced right ventricular ejection fraction (<40%) and right ventricular regional wall motion abnormalities (akinesia or dyskinesia). An abnormal radionuclide angiogram was observed in 12 of 13 patients with hemodynamic measurements indicating right ventricular infarction. In 12 patients with an abnormal radionuclide angiographic study, right ventricular ejection fraction improved 6 to 12 weeks after infarction (27 ± 7 to 36 ± 9%, p < 0.01).
Twenty-two (49%) of the 45 patients with adequate two-dimensional echocardiograms had a right ventricular regional wall motion abnormality. An abnormal two-dimensional echocardiogram was seen in 9 of 11 patients with hemodynamic measurements characteristic of right ventricular infarction. Technetium-99m pyrophosphate scintigraphy was positive for right ventricular infarction in 3 of 12 patients who had hemodynamic measurements indicating right ventricular infarction.
In conclusion: 1) volume loading significantly increases the identification of right ventricular infarction by hemodynamic criteria in patients with inferior transmural infarction, 2) radionuclide angiographic and two-dimensional echocardiographic evidence for right ventricular infarction is not always associated with abnormal hemodynamics even after volume loading, and 3) serial radionuclide studies in patients with inferior infarction with right ventricular infarction in the acute period often show improved right ventricular ejection fraction in the recovery period.
