Cardiac function after intermittent antegrade warm blood cardioplegia: contribution of the double-indicator dilution technique.

OBJECTIVE: To evaluate cardiac performance following coronary artery surgery using two different techniques of cardioplegia. DESIGN: Randomized prospective study. SETTING: Adult cardiothoracic intensive care unit in a university hospital. STUDY POPULATION: Thirty patients undergoing isolated coronary surgery. INTERVENTIONS: Patients were randomized to receive either intermittent antegrade warm blood cardioplegia with normothermic bypass (group 1) or combined antegrade and retrograde cold crystalloid cardioplegia with hypothermic bypass (group 2). Hemodynamic evaluation included conventional measurements from a pulmonary artery catheter and data obtained by thermal dye dilution utilizing an arterial thermistor-tipped fiberoptic catheter. RESULTS: The only major difference between groups was a significantly higher right atrial pressure in group 2, from 4 h to 24 h after surgery (8.8 +/- 2.6 vs. 11.8 +/- 3.2 mmHg at 4 h and 11 +/- 3.1 vs. 8.5 +/- 1.8 mmHg at 24 h, P = 0.04). After cold cardioplegia a significant increase in right atrial pressure was observed (7.5 +/- 3.1 before surgery vs. 11.4 +/- 3 mmHg at 8 h, P = 0.003) whereas right ventricular end diastolic volume index did not increase significantly, suggesting impaired right ventricular diastolic compliance in this group. CONCLUSIONS: Until 24 h after surgery cold cardioplegia is associated with impaired right ventricular filling, which seems better preserved by intermittent antegrade warm blood cardioplegia. End-diastolic volume measurement with the double-indicator technique allows differentiation between systolic and diastolic dysfunction.