M.Dar., F. Ciulli., T. Gillot., G.J. Cooper.

Department Of Cardiothoracic Surgery, Northern General Hospital, Sheffield.

Background: Application of a partial occluding aortic clamp during cardiopulmonary bypass may increase embolisation with consequent neurological injury. Using a single period of aortic clamping for coronary artery bypass grafting reduces aortic manipulation and may reduce this embolisation. We have investigated the influence of the technique of aortic cross clamping used during construction of the proximal anastomoses on neurological injury measured by S -100 levels.

Methods: Patients (n=49) undergoing coronary artery bypass grafting surgery were prospectively randomised into two groups. The single clamp technique was used for the construction of all the coronary artery anastomoses (Proximal and distal) in 25 patients (Group 1). The side biting clamp technique was used to construct the proximal anastomoses in 24 patients (Group 2). S-100 and Troponin T were measured pre and post operatively.

Results: The two groups were equally matched with regard to age ( G1; median 59, interquartile range (IQR) 55.5 to 61.5 years vs G2; 59, IQR 51.5 to 67.8 years), sex (male female ration G1; 21:4, G2; 20:4) and preoperative risk factors such as hypertension (G1; 7(28%), vs G2; 4(17%) and diabetes mellitus (G1; 2(8%), vs G2; 3(12.5%). There was no significant difference between the two groups in the mean number of grafts per patient (G1;3, IQR, 3 to 3, vs G2; 3, IQR, 2.25 to 3) and the cardiopulmonary bypass time (G1; 78, IQR, 60.5 to 87.5min., vs G2; 75.5, IQR, 51.5 to 117.3 min.). Aortic cross clamp time was significantly longer in G1; (52, IQR, 45to 63.5 min.), vs G2; (41.5, IQR, 30.25 to 57.75 min.) (P<0.04). There was no significant difference in Troponin T levels (G1; 0.62, IQR, 0.31 to 1.09m g/L, vs G2; 0.50, IQR, 0.35 to 1.09m g/L (P<0.97)(. S-100 levels were significantly lower in G1; (0.67, IQR, 0.40 to 0.84m g/L), compared to G2; (0.98, IQR, 0.61 to 1.11m g/L) (P<0.015).

Conclusion: This study suggests that despite a significant increase in the total ischemic time, there was no significant difference in myocardial damage between the two groups. S-100 levels were significantly lower in the single clamp technique group. Suggesting that the single clamp technique offers better cerebral protection than the conventional side biting clamp technique.