Left-sided myocardial revascularization with bilateral skeletonized internal thoracic artery

R. Mohr, A. Kramer

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

The current conventional and most commonly used operative procedure for myocardial revascularization includes one internal thoracic artery (ITA) together with one or more saphenous vein grafts (SVG) [1, 2]. Themajor surgical objective is to supply the left anterior descending coronary artery with an ITA in order to improve patient survival [3, 4]. ITA patency rate exceeds that of SVG and long-term patency remains high, in contrast to vein grafts which are subject to late closure as a result of progressive atherosclerosis [3]. Besides better survival, the superior patency rate is associated with better angina-free survival and decreased rates of reoperations and reinterventions [5]. Since SVG failure is a major drawback of coronary artery bypass grafting (CABG), surgical techniques of arterialmyocardial revascularization with minimal use of SVG were attempted. Two popular techniques for achieving this goal are bilateral and sequential ITA grafting [6-8]. In most centers, the ITA is isolated from the chest wall as a pedicle, together with the vein, muscle, fat and accompanying endothoracic fascia [3, 4, 9]. Harvesting is relatively quick due to the fact that cautery is used to separate the pedicle from the chest wall. However, cauterization damages the blood supply to the sternum, which in turn impedes sternal healing and exposes the sternum to the risks of early dehiscence and infection, particularly in operations in which both ITAs are used [10-13]. A surgical technique was recently developed wherein the ITA is dissected as a skeletonized vessel [14, 15]. The skeletonized artery is isolated gently with scissors and silver clips, without the use of cauterization. Skeletonized ITA dissection leaves the vein, muscle and accompanying tissue in place (Fig. 14.1). The advantage is that the dissected artery is longer [16] and its spontaneous blood flow is greater than that of the pedicled ITA [17], allowing the use of both ITAs as grafts to all necessary coronary vessels [9]. In many cases, no additional vein grafts are required [9]. Another advantage of using ITA as a skeletonized artery is the preservation of collateral blood supply to the sternum, enabling more rapid healing and decreasing the risk of infection [18]. The use of left ITA as a bypass graft has been shown to result in better early patency rate and improved survival in all patients, including elderly patients [13, 19], butmost published series have failed to show additional survival benefit with the use of bilateral ITA [1, 2]. The lack of survival benefits and the technical complexity of performing complete arterial revascularization with bilateral ITAs are the probable causes of the relative lack of popularity of this technique. The Society of Thoracic Surgeons (STS) database includes 153,000 CABG operations performed in the United States and Canada, only 4% of which involved the use of bilateral ITAs [20]. In contrast to most previously published reports, three important large-scale studies have shown that long-termsurvival with bilateral ITA is better than that with single ITA. Lytle et al. reported that the 10- and 15- year survival rates of bilateral ITA patients were 84% and 67%, compared to 79% and 64%, respectively, for patients with single ITA (p<0.001). Reoperative and angina-free survival, as well as freedom fromadditional revascularization procedures, was significantly higher in the bilateral ITA subset [21]. In another study performed by Buxton et al. [22], the 10-year actuarial survival of bilateral ITA patients was 86-3% compared to 71-5% for a single ITA (p<0.001). In that report, the use of bilateral ITAs improved the rate of freedomfrom late myocardial infarction and reoperations. The third report by Schmidt et al. demonstrated that survival benefit with bilateral ITA operations is achieved by grafting the ITA conduits to coronary arteries supplying the left ventricle (left-sided revascularization) rather than to the right coronary system [8]. Studies reporting results of bilateral ITA grafting contain preselected patients operated upon over a relatively long period [8, 9, 21, 22]. Most were non-obese and non-diabetic patients and were preselected for this procedure according to their life expectancy. Most of them were young and only a few of them were older than 70 years. The bilateral skeletonized ITA technique was adopted in the Tel Aviv Sourasky Medical Center in April 1996 as the preferred method for myocardial revascularization. Routine use of this ITA-harvesting technique enabled the surgeons to acquire the dexterity necessary for dissecting the skeletonized ITA and to minimize the time required for a learning curve. The routine use of SVG was stopped and since then vein grafts have been used as a third optional graft, in emergency CABG operations, or in cases with contraindications for the use of two ITAs. From April 1996 to July 1999, 1,000 consecutive patients underwent bilateral skeletonized ITA grafting. They comprised 71% of the 1,408 patients who underwent CABG during this time period in the Tel Aviv SouraskyMedical Center. This was a non-selected group of patients: there were 770 males and 230 females; 420 patients were older than 70 years and 312 were diabetic. Myocardial preservation technique was intermittent warm cardioplegia. The average number of grafts was 3.1 per patient [2-6]. The gastroepiploic artery was used in 231 patients and 158 saphenous vein grafts were implanted in 142 patients.

Original languageEnglish
Title of host publicationArterial Grafting for Coronary Artery Bypass Surgery
Subtitle of host publicationSecond Edition
PublisherSpringer Berlin Heidelberg
Pages130-139
Number of pages10
ISBN (Print)354030083X, 9783540300830
DOIs
StatePublished - 2006
Externally publishedYes

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