Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery.

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.

Echocardiographic characterization of left ventricular diastolic properties in patients presenting for the maze procedure.

The aim of this study is to characterize and compare the left ventricular (LV) diastolic filling patterns in patients with paroxysmal (PAF) versus chronic atrial fibrillation (CAF) undergoing the maze procedure and to examine their relation with the hemodynamic status. Fifty patients with PAF and 22 with CAF were studied. Hemodynamic measurements and transesophageal echocardiography (TEE) were performed after the induction of anesthesia but before surgical incision, at stable conditions. Transmitral (TMF) and pulmonary venous flow (PVF) velocities were recorded with the pulsed Doppler method. Statistical analysis between the two groups (PAF and CAF) was performed using Student's t-test and chi-squared test, with P less than .05 statistically significant. Compared with patients in the PAF group, those in the CAF group had: (1) higher pulmonary capillary wedge pressure (14 +/- 5 v 12 +/- 4 mm Hg; P < .05), (2) lower left ventricular fraction of area change (43% +/- 6% v 52% +/- 9%; P < .01), (3) slower PVF systolic wave velocity (23 +/- 10 v 35 +/- 15 cm/s; P < .05), and (4) lower ratio of PVF systolic to diastolic wave velocity (0.75 +/- 0.3 v 1.2 +/- 0.4; P < .05). In the present study, LV filling patterns of abnormal relaxation were found in all our patients who underwent the maze procedure for CAF or PAF. Although the cause of LV filling abnormalities is not apparent, the data suggest LV diastolic dysfunction is prevalent in these patients.