Ann Thorac Surg 2007;83:2098-2102
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Exclusive Internal Thoracic Artery Grafting in Triple-Vessel–Disease Patients: Angiographic Control
Alexandre Azmoun, MDa,*,
Ramzi Ramadan, MDa,
Nawwar Al-Attar, FRCS, PhDa,
Chokri Kortas, MDa,
Said Ghostine, MDa,
Christophe Caussin, MDa,
Marie-Laure Bourachot, MDa,
Bernard Lancelin, MDa,
Michel Slama, MD, PhDb,
Remi Nottin, MDa
a Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France
b Hospital Antoine Beclere, Clamart, France
Accepted for publication February 14, 2007.
* Address correspondence to Dr Azmoun, Centre Chirurgical Marie Lannelongue, 133 Avenue de la Resistance, Le Plessis Robinson, 92350, France (Email: azmoun{at}yahoo.com).
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Abstract
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Background: The internal thoracic artery (ITA) is considered to be the conduit of choice for coronary artery bypass grafting surgery (CABG). In triple-vessel–disease patients, CABG can be performed exclusively using both ITAs in a Y fashion with multiple sequential side-to-side coronary anastomoses. The aim of this prospective study was to evaluate by early postoperative angiographic control, the patency and particularly the quality of ITA grafts and coronary anastomoses in this configuration.
Methods: Between October 2002 and October 2003, 92 triple-vessel–disease patients underwent CABG with this technique and consented to immediate postoperative angiographic control. The right ITA was divided at its origin and connected to the in-situ left ITA (ITA-Y anastomosis). The left ITA was anastomosed to anterior coronary arteries and the right ITA was anastomosed to lateral and inferior coronary arteries, for a total of 374 coronary anastomoses (4.1 anastomoses per patient; range, 3 to 6).
Results: There was 1 hospital death by septic shock. Two patients were reoperated on for superficial wound infection. There was no postoperative myocardial infarction or stroke. On postoperative angiograms, all ITA-Y (92) and ITA-coronary anastomoses (374) were patent. Competition of flow in right ITA to the moderately stenosed right coronary artery was observed in 9 patients, and there were 4 distal ITA-coronary stenoses, both without clinical consequences.
Conclusions: In triple-vessel–disease patients, this procedure allows CABG without increasing operative risk. ITA-Y anastomoses and multiple sequential side-to-side ITA-coronary anastomoses are safe to perform and demonstrate excellent patency and quality in early postoperative angiographic control, particularly when coronary artery stenoses are significant (>70%).
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Introduction
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The internal thoracic artery (ITA) is considered to be the conduit of choice for coronary artery bypass grafting (CABG) [1–7]. Furthermore, some recent data suggest that the use of both ITAs seems to be superior to the use of single ITA [8–12]. In triple-vessel–disease patients, CABG can be performed using exclusively ITAs grafts. One of the techniques that allows achieving this goal is connecting the free right ITA (RITA) end to side, to the in-situ left ITA (LITA) as a Y graft and has been already reported [13, 14]. This technique requires performing multiple sequential side-to-side ITA-coronary anastomoses and so allows increasing the number of arterial coronary anastomoses with ITA without using any other type of graft.
This technique has not been widely adopted, however, and controversies still remain about its efficiency, the reserve blood flow in LITA for the entire heart especially in immediate follow-up, the length of the free RITA to reach the right coronary artery without stretch, safety and feasibility of multiple sequential side-to-side ITA-coronary anastomoses, and particularly the phenomenon of competition of flow. On the other hand, the ITA-Y anastomoses and multiple sequential side-to-side ITA-coronary anastomoses have not been systematically evaluated in large studies by direct graft visualization. Their patency was usually inferred from clinical signs or nonspecific evaluation methods (scintigraphy, exercise electrocardiogram, and so forth). The aim of this prospective study was to evaluate by early postoperative coronary angiography the patency and particularly the quality of grafts, ITA-Y anastomoses, and multiple sequential side-to-side ITA-coronary anastomoses in this configuration, in triple-vessel–disease patients.
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Patients and Methods
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From October 2002 through October 2003, 305 triple-vessel–disease patients underwent first elective isolated CABG in our department. Arterial grafts (ITA, radial artery, and gastroepiploic artery) were always used in these nonemergency cases, and no patient received saphenous vein graft. According to the surgeon’s preference, 133 of these patients had single or bilateral ITA in association with radial or gastroepiploic artery grafts, and 172 others underwent CABG using exclusively both ITAs grafts in the Y configuration. Among these 172 patients, 80 refused a postoperative coronary angiographic control and were excluded from the study. The remaining 92 patients (81 men and 11 women) with a mean age of 64.4 years (±10.6 years) consented to the coronary artery angiographic control before hospital discharge and are presented here. Patients’ preoperative clinical characteristics and their operative risk factors are summarized in Table 1. The exclusion criteria were emergency cases with cardiogenic shock or left subclavian artery stenosis assessed by preoperative Duplex ultrasonography.
Local Ethics Committee approval was obtained, and 92 patients gave individual informed consent to be controlled by postoperative coronary angiography.
The surgical technique consisted of complete skeletonized harvesting of both ITAs to obtain maximum length. The RITA was divided at its origin and connected end to side to the in-situ LITA in a Y fashion. Construction of this ITA-Y anastomosis was always performed by a linear incision in the LITA and end-to-side anastomosis of the free RITA by a single 8-0 polypropylene running suture, before placing the patient on cardiopulmonary bypass (CPB). That allowed visual assessment of the quality of flow in both limbs of the Y graft before performing the distal anastomoses. A topical infusion of diluted papaverine (4 mg/20 mL Ringer solution) was sprayed on the body of grafts, and heparin sodium (3 mg/kg) was administered. Both limbs of ITA graft were then clipped at the end and left pulsating in-situ until use. No therapy with vasodilators or calcium-channel blockers was given.
The LITA was destined to the anterior coronary arteries and the RITA to the lateral and inferior coronary arteries of the heart in a sequential fashion by constructing side-to-side and end-to-side coronary anastomoses. All distal ITA-coronary anastomoses were performed under aortic cross clamping and cardioplegic arrest. Interventions were always performed under normothermia with antegrade discontinued warm blood cardioplegia. The mean aortic cross-clamping time was 58 minutes (±8), and the mean CPB time was 65 minutes (±12). The LITA was anastomosed to the left anterior descending artery (n = 97), ramus intermedius artery (n = 8), and diagonal artery (n = 61). The RITA was anastomosed to the ramus intermedius artery (n = 13), obtuse marginal artery (n = 95), right posterolateral artery (n = 26), and posterior descending artery (n = 74; Fig 1,
Table 2). A total of 374 ITA-coronary anastomoses were performed, for an average of 4.1 anastomoses per patient (3 to 6 anastomoses per patient). In these patients, all coronary arteries with stenosis of 70% or more or left main stenosis of 50% or more were grafted with at least one bypassed coronary artery in each coronary territory (anterior, lateral, and inferior). In patients with stenosis of the right coronary artery associated with an isolated stenosis of the left main stem (without significant stenoses in the left anterior descending and the circumflex arteries), the same technique was used: the left anterior descending artery was bypassed with the LITA; the obtuse marginal and posterior descending arteries were bypassed with the RITA.
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Fig 1. Schematic representation of the anastomosis of RITA on LITA in the Y configuration and sequential internal thoracic artery-coronary anastomoses. (D = diagonal artery; LAD = left anterior descending artery; LITA = left internal thoracic artery; OM = obtuse marginal artery; PD = posterior descending artery; RI = ramus intermedius artery; RITA = right internal thoracic artery; RPL = right posterolateral artery.)
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All patients had sternal wiring with two longitudinal transsternal wire loops. The two halves of the sternum were then tightly opposed by means of multiple single-suture wires tightened against the longitudinal wires.
Graft visualization studies were performed before hospital discharge (9 ± 1.4 days) by left radial artery approach with selective catheterization of the in-situ LITA using an IM Supertorque Plus catheter (Cordis; Johnson and Johnson, Miami, Florida). Heparin sodium (5,000 IU) and verapamil (3 mg) were injected in the radial artery to prevent arterial spasm. Nitrates (1 mg isosorbid dinitrate) were then injected in the LITA, and four orthogonal views were systematically obtained: right anterior oblique caudal projection, anteroposterior cranial projection, left anterior oblique caudal projection, and left lateral projection. All angiograms were analyzed independently by two experienced operators. Each ITA graft was visually evaluated for occlusion, development of "string" sign (conduit diameter less than 1 mm), presence of significant stenosis, or abnormality at any point within the body of the graft or at the coronary anastomoses.
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Results
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One noncardiac hospital death (1.1%) was subsequent to pulmonary infection and septic shock. Five patients had wound infection, all with favorable outcome. Three had type II diabetes melletus, 1 had type I diabetes, and 1 patient was not diabetic. In all cases, the infection was superficial. Three had conservative medical treatment with antibiotics after culture, and 2 had superficial wound debridement without sternum reopening, closed suction drainage, and antibiotics. No patient had mediastinitis.
There was no postoperative myocardial infarction assessed by postoperative cardiac enzyme monitoring (creatine kinase-MB and troponin), electrocardiography, and echocardiography. Postoperative intra-aortic balloon pump was never required. There was no postoperative stroke. Postoperative complications are summarized in Table 3.
On postoperative angiograms (Fig 2), all ITA-Y anastomoses (n = 92) and all ITA-coronary anastomoses (n = 374) were patent. No abnormality was observed on ITA-Y anastomoses. There were 4 ITA-coronary anastomoses stenoses (1.1%; Fig. 3) without any flow abnormality or clinical manifestation: 1 left anterior descending artery, 1 diagonal artery, 1 obtuse marginal artery, and 1 posterior descending artery. Two of these patients had a subsequent angiogram, 4 and 5 months later. In both of them, the anastomotic stenosis disappeared (Fig 3). Graft kinking was observed on the body of the RITA in 3 patients. Two of them were followed up by subsequent angiography at 6 and 9 months; the graft kinking had disappeared in both. Competition of flow in the RITA to the right coronary artery or its branches was observed in 9 patients. In all of these patients, postoperative opacification of the native coronary arteries showed perfect patency of the RITA graft, visualized by retrograde flow without any clinical consequences. There was no complication from catheterization of the in-situ LITA grafts for angiographic control.
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Fig 2. Postoperative coronary angiograms showing Y graft. (LITA = left internal thoracic artery; RITA = right internal thoracic artery.)
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Fig 3. Postoperative angiographic abnormalities: (A) anastomotic stenosis on right internal thoracic artery to posterior descending artery (arrow); (B) anastomotic stenosis has disappeared 4 months later (arrow).
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All patients had an electrocardiographic exercise test the first month after discharge. None of them had a positive test, and none had recurrence of angina.
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Comment
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In triple-vessel–disease patients, CABG exclusively using ITA-Y grafts with multiple sequential side-to-side ITA-coronary anastomoses introduces the concept of coronary arterial tree reconstruction by the most appropriate conduit. It capitalizes on the best expected longevity of this graft. Nevertheless, this technique has not been widely adopted with controversies about its efficiency.
That total coronary bypass flow is dependent on the flow of the proximal LITA in this procedure has led to concern whether flow reserve in the LITA is sufficient to supply more than one coronary anastomosis and even more, for the entire heart. Several reports have already concluded that ITA-Y graft permits complete myocardial revascularization with good perioperative results and that the flow reserve of the proximal LITA is adequate for multiple coronary anastomoses [15, 16]. In our angiographic study, when the coronary artery stenoses were significant (>70%), the flow in the proximal LITA allowed the complete perfusion of all bypassed coronary arteries. However, the competition of flow in the RITA to the right coronary artery or its branches at conditions of rest occurred in 9 patients. After reviewing the preoperative angiograms, the native right coronary artery lesions were found to be overestimated and were in fact inferior to 70%. Even in this situation, ITA grafts still demonstrated perfect early patency assessed by retrograde flow from postoperative opacification of the native right coronary artery. These angiographic data suggest that in case of a large dominant right coronary artery with a moderate stenosis, this technique may experience the phenomenon of competition of flow. However, these angiographic abnormalities had no postoperative consequences, as patients were asymptomatic on discharge with an early postoperative negative electrocardiographic exercise test. Nevertheless, this technique remains questionable in such situation. Other techniques then could be proposed to bypass a dominant right coronary artery with a moderate stenosis [14].
Controversy still persists on whether the RITA is long enough to reach the right coronary artery without stretch. Indeed, completely skeletonized harvesting of ITAs is of great importance to provide enough length to reach the right coronary system. In our series, we were never short of length to bypass the right coronary artery branches (right posterolateral or posterior descending arteries). In this study, postoperative opacification of grafts showed no angiographic evidence of traction or stretch at any point of conduits or coronary anastomoses.
Another matter of concern is whether the ITA-Y grafts and multiple sequential side-to-side ITA-coronary anastomoses are safe to perform. Early angiographic follow-up in this study allowed visual control of the quality of the ITA-Y anastomoses and sequential side-to-side ITA-coronary anastomoses and the distal run-offs in the native coronary arteries. The risk of anastomotic stenosis is minor in this series (1.1%), and it together with occasional graft kinking have both been shown to be transient. This phenomenon has also been reported by some authors [17] as the ITA graft stenosis at the anastomotic site detected at early postoperative angiography might improve without intervention therapy.
Harvesting of both ITAs may reduce the sternum vascularization, particularly in diabetic patients. To obtain good sternum stability, all patients had reinforced sternal wiring with two additional longitudinal wire loops. Of the 5 patients who had wound infection, 4 were diabetic. Two of them were reoperated on with superficial wound toileting and medical management; in these patients, there was perfect sternum stability without the need for sternum reopening. The three remaining patients were simply treated conservatively. In all cases, the infection was superficial with favorable outcome. Thus in this series, diabetes mellitus seems to be a risk factor for superficial wound infection.
This immediate postoperative angiographic evaluation shows that in triple-vessel–disease patients, ITA-Y anastomoses and multiple sequential side-to-side ITA-coronary anastomoses are reproducible and safe to perform routinely with excellent angiographic results when coronary artery stenoses are significant.
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Abstract
Introduction
