Early effects of coronary artery bypass surgery and cold cardioplegic ischemia on left ventricular diastolic function: evaluation by computer-assisted transesophageal echocardiography.

OBJECTIVE: Although left ventricular (LV) systolic function undergoes a temporary decrease after cardiopulmonary bypass (CPB) in patients undergoing coronary artery bypass grafting (CABG), data on the effects of CABG and cardioplegic arrest on LV diastolic function are contradictory. The objective of the present study was to further evaluate the effects of CABG and CPB on LV diastolic function.

DESIGN: A prospective study.

SETTING: A multi-institutional investigation at a university hospital.

PARTICIPANTS: 20 patients on beta-receptor antagonists, scheduled for CABG and with a preoperative ejection fraction over 0.5.

INTERVENTIONS: Central hemodynamic measurements, transesophageal LV short-axis images, and mitral Doppler flow profiles were obtained before and after volume loading that in turn was performed both before surgical incision and after weaning from CPB.

MEASUREMENTS AND MAIN RESULTS: Heart rate, cardiac output, and peak atrial filling velocity increased; systemic vascular resistance decreased; whereas stroke volume, LV area ejection fraction, deceleration rate and slope of early diastolic filling, time-velocity integral of early diastolic filling, and the ratio between early and atrial peak filling velocity were unchanged post-CPB compared with pre-CPB. LV end-diastolic stiffness that was calculated for each patient pre-CPB and post-CPB using the formula: P = B*eS*A), where P is the LV filling pressure and A is the end-diastolic short-axis area, was unchanged post-CPB compared with pre-CPB.

CONCLUSIONS: Both the active and passive components of LV diastolic function are well maintained shortly after CABG and cardioplegic arrest in patients with a good preoperative systolic LV function.