Single-clamp technique does not protect against cerebrovascular accident in coronary artery bypass grafting

European Journal of Cardio-thoracic Surgery 20 (2001) 127±132 www.elsevier.com/locate/ejcts Single-clamp technique does not protect against cerebrovascular accident in coronary artery bypass grafting q a Department of Surgery, Section of Cardiothoracic Surgery, Yale University School of Medicine, New Haven, CT 06510, USA b Center for Outcomes Research, Yale±New Haven Hospital, New Haven, CT 06510, USA Received 11 December 2000; received in revised form 10 April 2001; accepted 23 April 2001 Abstract Objectives: By potentially avoiding the embolic consequences of a side-biting aortic clamp, the single-clamp technique may decrease cerebrovascular accidents in coronary artery bypass grafting. However, this theoretical superiority in stroke prevention has not been conclusively demonstrated and use of this technique may lead to adverse myocardial effects due to longer cross-clamp times. In this study, we sought to determine if the single-clamp technique prevents postoperative stroke in clinical practice. Methods: Of 607 consecutive isolated coronary bypass operations completed over a 3 year period, 301 (50%) were performed by one surgeon using exclusively the singleclamp technique and 306 (50%) were performed by a second surgeon using exclusively the two-clamp technique. Postoperative adverse events were retrospectively compared between these two groups. Results: There were no differences between groups in terms of postoperative stroke (1.7% single-clamp vs. 2.0% two-clamp, P ˆ 0:78), hospital mortality (2.7% single-clamp vs. 1.6% two-clamp, P ˆ 0:38), or perioperative myocardial infarction (2.6% single-clamp vs. 0.7% two-clamp, P ˆ 0:052). The two-clamp technique was not a signi®cant predictor of stroke by logistic regression analysis (P ˆ 0:72). Conclusions: We conclude that there are no statistically signi®cant differences between clamp techniques with regard to stroke prevention or myocardial protection. We ®nd no compelling evidence for surgeons successfully utilizing one technique to change to the other. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Coronary disease; Surgery; Stroke; Complications 1. Introduction Proposed by Buckberg [1] and developed and popularized by Salerno [2] and Aranki et al. [3,4], the single aortic crossclamp technique for coronary artery bypass grafting (CABG) is based on sound theoretical grounds. By eliminating the second, partially occluding aortic clamp, this technique may potentially decrease the incidence of embolic stroke in CABG. Accordingly, the single-clamp technique has been gaining popularity among cardiac surgeons. However, the clinical superiority of this technique for stroke prevention has not been conclusively demonstrated. In fact, the few studies in the literature that have looked directly at this issue have, for the most part, failed to demonstrate cardiac or cerebral bene®t directly attributable to this technique [3,5± 9]. Although avoiding the application of the conventional q Presented at the 36th Annual Meeting of the Society for Thoracic Surgeons, Fort Lauderdale, FL, USA, January 31±February 2, 2000. * Corresponding author. Tel.: 11-203-785-2705; fax: 11-203-785-3346. E-mail address: (J.A. Elefteriades). second clamp may decrease the number of aortic emboli [10], this method necessarily results in longer cross-clamp times and converts the otherwise closed bypass operation to an open procedure, with increased risk of cardiac and cerebral air embolization. The open aorta may also complicate venting of the left ventricle by gravity or suction. Surgeons currently using the conventional two-clamp technique also question the potential adverse myocardial effects attendant to the extended period of aortic crossclamping inherent in the single-clamp technique. Supporters of the single-clamp technique argue that using a single clamp allows for more uniform cardioplegia delivery as the grafts are constructed and better prepares the myocardium for reperfusion following clamp release [3,4]. Conversely, proponents of the two-clamp technique maintain that no preservation technique is better than early removal of the cross-clamp and point to the bene®cial immediate release of the internal mammary artery graft possible with the twoclamp technique. The balance of these various factors is not clear. We recognized an opportunity to study this issue as two 1010-7940/01/$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. PII: S 1010-794 0(01)00765-5 Richard W. Kim a, Dominick C. Mariconda a, George Tellides a, Gary S. Kopf a, Michael L. Dewar a, Zhenqui Lin b, John A. Elefteriades a,* 128 R.W. Kim et al. / European Journal of Cardio-thoracic Surgery 20 (2001) 127±132 con®rmed postoperative diagnosis of stroke. All available cerebral radiographic imaging was obtained on these patients and reviewed with a neuroradiologist to characterize the stroke, where possible, as embolic, non-embolic ischemic, or hemorrhagic. 2. Materials and methods 2.3. Operative technique 2.1. Patients All patients underwent isolated CABG surgery using cardiopulmonary bypass and moderate systemic hypothermia (28±328C). Myocardial preservation was achieved with topical hypothermia using iced saline, and antegrade cold blood or crystalloid cardioplegia. The two-clamp surgeon utilized cold crystalloid cardioplegia given antegrade. The single-clamp surgeon utilized blood cardioplegia also given antegrade. In the single-clamp method, distal and proximal anastomoses were constructed during a single period of aortic occlusion. Grafting of the internal mammary artery was performed following the sequential completion of saphenous vein anastomoses. Additional cardioplegia was delivered upon completion of each proximal anastomosis. In the two-clamp method, proximal anastomoses were constructed following release of the initial aortic clamp and after applying a second partially occluding aortic clamp. This method allowed for early reperfusion of the heart and early release of the internal mammary artery graft. Although almost all patients in both groups underwent pedicled left internal mammary artery grafting, sequential arterial or `Y' grafting was not utilized by either surgeon. Six hundred and seven consecutive patients who underwent isolated CABG surgery by two equally experienced cardiac surgeons at Yale±New Haven Hospital constituted the study group. All patients having associated valvular, aortic, or left ventricular aneurysm repairs were eliminated, as were all patients having off-pump CABG and all patients having concomitant carotid endarterectomy. These patients were operated upon during a 3-year period extending from October 1996 to September 1999. Three hundred and one (50%) patients underwent surgery via the single-clamp technique (by one surgeon) while 306 (50%) patients underwent CABG using the two-clamp technique (by the other surgeon). Segregation into each treatment group was based upon the routine practice o (...truncated)