Study design validation for consolidating global with focal neurological events in cardiac surgery stroke risk factor analyses.

Neuroimaging shows that both global and focal neurologic deficits after cardiac surgery share an acute, often multifocal, embolic cerebral infarction etiology; yet, analyses of stroke risk factors historically have emphasized the focal deficits. We test if consolidating encephalopathy and coma with focal deficits affects four stroke risk factors and a dummy variable. Overall focal and global events in 575 cardiopulmonary bypass operations identified by retrospective review matched indices reported in large prospective studies. Logistic regression in 189 records selected for completed non-invasive preoperative carotid stenosis screening showed all four conventional stroke risk factors to be independent predictors of overall consolidated global plus focal neurologic risk, specifically: age [odds ratio (OR) 1.90 per decade], carotid stenosis >50% (OR 1.91), pump time (OR 1.67 per hour), open chamber (OR 1.95); and successfully eliminated the dummy variable gender (P = 0.6). This analysis indicates that the design of future stroke risk factor studies in the setting of cardiac surgery can and should adopt a neuroimaging evidence-based investigative approach of consolidating global with focal deficits.

Heparin-protamine mismatch. A controllable factor in bleeding after open heart surgery.

OBJECTIVE: To test the effect of a new system designed to reduce heparin-protamine mismatch on bleeding after open heart surgery. DESIGN: Nonrandomized but consecutive retrospective review of patients undergoing open heart surgery during a 9-month period. SETTING: Multispecialty referral center. PATIENTS: A total of 150 patients comparable by age, body surface area, and coagulation status undergoing primary open heart surgery for either coronary bypass or heart valve replacement. INTERVENTION: In the first 75 patients (group 1), heparin sodium was neutralized with protamine sulfate, using a fixed ratio (1 mg of heparin sodium to 1.3 mg of protamine sulfate). An activated clotting time was used to confirm heparin neutralization. For the subsequent 75 patients (group 2), titration of heparin and protamine from defined lots was accomplished using activated clotting times adjusted and matched to drug lots to minimize biologic variability. Groups 1 and 2 had comparable operations, pump times, and cross-clamp times. MAIN OUTCOME MEASURES: Doses of heparin and protamine and their effect on blood product transfusion and postoperative bleeding were evaluated in all patients. RESULTS: The average protamine sulfate dose for group 2 patients (287.56 +/- 8.3 mg) was significantly lower than that for group 1 (346.01 +/- 12.6 mg) (P < .0005). Less protamine was associated with the transfusion of fewer red blood cells (0.92 +/- 0.15 vs 2.57 +/- 0.38 U) (P < .001), platelets (0.72 +/- 0.8 vs 2.96 +/- 0.80 U) (P < .01), and fresh-frozen plasma (0.83 +/- 2.0 vs 2.01 +/- 0.48 U) (P < .03). No patients in group 2 required reexploration for bleeding, compared with eight patients in group 1. CONCLUSIONS: A reduction in protamine dose was associated with significant decreases in blood product use and postoperative bleeding. Excess protamine warrants consideration as both an important and a controllable factor in coagulopathy after open heart surgery.

Postperfusion coronary stenosis.

A patient is described who had left main coronary artery stenosis four months after aortic valve replacement. He was seen with unstable angina, and subsequent catheterization revealed stenosis of a previously normal left main coronary artery. The diagnosis, treatment, and means of prevention are discussed.