Protamine: does it alter right ventricular function?

Protamine administration has been associated with cardiac decompensation secondary to acute pulmonary vasoconstriction and subsequent right ventricular failure. To determine whether protamine infusion produced alterations in right ventricular performance, we evaluated both right and left ventricular function in patients receiving protamine infusion. The dose of protamine administered was calculated as adequate to reverse heparin as measured by the activated clotting time (ACT). Indices of right and left ventricular function obtained included right atrial pressure, right ventricular pressure, right ventricular ejection fraction, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, blood pressure, and heart rate. These measurements were obtained prior to protamine administration, at 1/2 total protamine dose, at completion of protamine infusion, and prior to sternal closure. No significant changes in right ventricular ejection fraction, right ventricular end-diastolic pressure, mean pulmonary artery pressure, or pulmonary vascular resistance were seen at any point during the study. Left ventricular function remained unchanged. Even in patients who are possibly at an increased risk (pulmonary artery hypertension, PAP greater than 25 mm Hg), no deterioration in right or left ventricular function could be demonstrated following protamine administration. These data suggest that protamine does not consistently exert a significant detrimental effect on right ventricular performance.