Changes in jugular venous flow velocity after coronary artery bypass grafting.

The factors underlying postoperative jugular venous flow velocity and pulse contour changes were studied in 25 patients undergoing coronary artery bypass grafting. Before operation, all patients had normal right-sided cardiac hemodynamics, normal jugular pulse contours and normal jugular venous flow velocity patterns, i.e., systolic flow (SF) velocity greater than diastolic flow (DF) velocity. After operation, jugular venous flow velocity was abnormal in 24 patients (SF = DF in 14 and SF less than DF in 10). Neither the right-sided cardiac pressures after the operation nor any of the perioperative factors examined had any bearing on these flow alterations. Postoperative right ventricular ejection fraction was normal in all 5 patients with SF greater than DF and SF = DF flow patterns (mean +/- standard error of the mean 48 +/- 3%). It was significantly depressed in all 6 patients with SF less than DF flow pattern (34 +/- 1%, 2p less than 0.001). These findings suggest that the right atrium behaves as a conduit rather than a capacitance chamber. However, the postoperative abnormal flow pattern of SF less than DF as opposed to SF = DF indicates the additional presence of right ventricular dysfunction. The implications of these observations for the clinical assessment of right ventricular function in the postoperative patients are discussed.