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Ann Thorac Surg 2002;73:1431-1435
© 2002 The Society of Thoracic Surgeons
a National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, Harefield Hospital, Middlesex, United Kingdom
Accepted for publication December 21, 2001.
* Address reprint requests to Mr Amrani, Cardiac Surgery, Harefield Hospital, Middlesex UB9 6JH, UK
e-mail: mr.amrani{at}rbh.nthames.nhs.uk
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Abstract |
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Methods. The records of 212 consecutive patients who underwent isolated coronary artery bypass grafting with the pedicled RITA graft to the LAD artery at Harefield Hospital between January 1998 and May 2001 were retrospectively reviewed. We approached the last 35 consecutive patients to obtain an angiographic control group. All 35 patients (16.5%) consented and, before discharge, underwent angiography to look at the quality of anastomoses and the patency of grafts.
Results. Successful catheterization and engagement of the RITA grafts was performed in 32 patients. Angiography showed that 32/32 (100%) of the RITA grafts were widely patent with excellent flow. The distal anastomoses of these RITA grafts were also satisfactory. There were no deaths among the study patients.
Conclusions. Our results show that the use of the pedicled RITA graft to the LAD artery provides a good early clinical and angiographic outcome, and suggests that the pedicled RITA graft to the LAD artery is a good alternative to the pedicled LITA graft to the LAD artery.
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Introduction |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Patients and methods |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Anesthesia
Anesthesia was induced using propofol 1 to 2 mg/kg, pancuronium 0.1 mg/kg, and fentanyl 8 to 15 µg/kg; it was then maintained by air/oxygen and propofol 2 to 3 mg · kg-1 · h-1. Transesophageal echocardiography (TEE) was used for additional monitoring as required. For OPCAB cases, normothermia was maintained by using warm intravenous fluids, a heating mattress, and a humidified airway; in addition to a warm operating theater. A standby perfusionist with primed bypass circuit was available for all OPCAB cases.
Surgical technique
Approach and exposure
In this technique, a standard midline sternotomy incision is used to expose the heart. The pericardium is opened using an inverted T-shaped incision after harvest of the ITAs. Opening the right pleural space and dissecting the pleura for the entire length of the RITA provides two advantages: first, it gives more length of the RITA [9]; and second, it creates a space for the rotated and verticalized heart to minimize hemodynamic compromise when performing the operation off-pump. This is followed by an evaluation of the status of coronary artery and the lengths of both ITAs.
CPB technique
Anticoagulation was achieved using 250 U/kg of heparin. The activated clotting time was maintained at more than 480 seconds. Heparin was reversed by protamine at the end of the procedure. Cardiopulmonary bypass was instituted with a single right atrial cannula and an ascending aorta perfusion cannula. Standard bypass management included membrane oxygenators, arterial line filters, nonpulsatile flow of 2.4 L/min/m2, with a mean arterial blood pressure greater than 50 mm Hg. Myocardial protection was achieved with intermittent cold blood cardioplegia (blood to crystalloid ratio, 4:1).
Cardiac stabilization and manipulation
Anticoagulation was achieved using 150 U/kg of heparin. The activated clotting time was maintained at more than 250 seconds. Of the study patients, 193 (91%) were operated on using the OPCAB technique. The heart is stabilized using the suction/irrigation tissue stabilization system (Octopus 3 Medtronic Inc, Minneapolis, MN). One deep pericardial retraction suture is placed at the posterior fibrous pericardium, very close and medial to the most proximal part of the inferior vena cava (IVC); this acts as a lever that helps the surgeon to manipulate and rotate the heart to vertical and lateral positions along with the Octopus. A wet gauze swab is placed between the suture and the posterior surface of the heart to avoid tearing the myocardium or compressing of the posterior coronary vessels.
Harvest of RITA
The right and left internal thoracic arteries are harvested as wide pedicles including artery, vein, muscle, fascia, and adipose tissue. In the absence of evidence, by a randomized trial, to show the superiority of the skeletonization technique in harvesting the ITA grafts [10], we kept the wide pedicle technique. However, we acknowledge the advantage of avoiding the bulkiness of the pedicle by limiting the amount of tissues taken down with it [11]. Gentle dissection is begun at the distal end of the artery to ensure adequate length in case of inadvertent injury. We extend the dissection proximally as far as the subclavian artery. The RITA is brought to the left side through a right pericardial incision crossing over the aorta and pulmonary trunk, as far cranial as possible, and passing behind the thymus gland [12] (Figs 1, 2, and 3).
The RITA pedicle becomes completely wrapped by the thymic tissue to separate it from the sternum. The RITA is sprayed with diluted papaverine solution (50 mg/20 mL normal saline) and a bulldog is applied to control bleeding from the distal end. The pedicled RITA to LAD graft is performed first in OPCAB cases and performed last in CPB. If the distal segment of the LAD needs to be reached, a longitudinal and transverse fasciotomy of the pedicle is performed. This maneuver has always allowed us to reach any segment of the LAD.
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Results |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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This group of patients represents a consecutive series of selective application of full or partial arterial revascularization, in which pedicled RITA to LAD graft was used in conjunction with pedicled LITA graft to Cx. All operations were performed by a single surgeon (M.A.) using mainly the OPCAB technique.
Angiography
Angiography was performed on 35 of the 212 patients (16.5%) before discharge at the earliest on postoperative day 4. All 35 patients studied by angiography underwent operation with the OPCAB technique.
The visualization of the RITA grafts was successful in 32 patients. In 1 patient, the angiographic procedure was abandoned before catheterizing the RITA graft because of advanced age and frailty. In 2 patients, selective engagement of the pedicled RITA grafts using the available types of cardiac catheters was not possible, and the procedures were abandoned. All grafts and anastomoses were viewed in at least two orthogonal views. All the catheterized pedicled RITA grafts to the LAD artery in 32/32 cases (100%) were patent, with good quality distal anastomoses (Figs 1, 2, and 3).
In contrast, selective engagement of all the pedicled LITA grafts was possible in all 35 patients. All LITA grafts to the Cx and its OM branches (35/35 cases, 100%) were patent, with good quality distal anastomoses. The 35 patients studied by angiography also had 26 radial grafts and 15 vein grafts. One radial graft was occluded, and another radial graft had a string sign but a good-quality distal anastomosis. All 15 vein grafts were patent with good-quality distal anastomoses.
Postoperative course
There were no deaths among the study patients. Postoperative complications are listed in Table 2.
Pulmonary complications occurred in 3 patients (1.1%) who required reintubation and ventilation, and in 2 patients (0.7%) who required tracheostomy. These 5 patients developed persistent hypoxia in the immediate postoperative period due to adult respiratory distress syndrome (n = 2) and lung collapse (n = 3) without evidence of phrenic nerve injury or pleural effusion on postoperative chest x-rays. Five (2.3%) patients developed low cardiac output, which resolved by adequate filling and use of inotropic agents. Myocardial infarction was excluded in those 5 patients by electrocardiography and cardiac enzymes.
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Comment |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Because of the well-documented benefits of long-term survival and excellent patency, the pedicled LITA graft to LAD artery has become the gold standard in coronary bypass surgery. The proposed underlying mechanisms of those benefits include the following: reduced late cardiac events [1–5]; high resistance to the development of arteriosclerosis [13–15]; patency superior to that of the saphenous vein grafts [2, 4, 5, 16–18]; and the ability to autoregulate its flow and to minimize competitive flow in the native coronary artery [19].
Given the proven advantages of the LITA to LAD graft, some authors advocated a more extensive use of the RITA to LAD [8, 20]. Recent data shows that the use of bilateral ITA grafts improves outcome even more than single pedicled ITA graft in addition to allowing an increase in the number of distal anastomoses, while reducing the manipulation of the aorta [21–23]. For the same reason, others have used the ITA grafts as free grafts off the aorta. However, the clinical and angiographic outcomes of those free ITA grafts proved to be less satisfactory. Indeed, free ITA grafts anastomosed to the aorta have a lower patency because of more turbulence causing intimal damage than pedicled ITA grafts [8, 24, 25]. The difference in patency was reported to be as high as 25% [8].
Because of well-established clinical and angiographic superiority of the pedicled ITA grafts, and because of the excellent clinical and angiographic data shown in our institution and others [8, 20], it is our policy first to use the pedicled LITA graft to LAD and pedicled RITA graft to the Cx through the transverse sinus [26–28]. When this is not feasible (eg, in the case of distal Cx vessel), the second best combination is pedicled RITA to LAD and pedicled LITA to Cx. This strategy allows one to keep both ITAs pedicled. By using the longitudinal and transverse fasciotomy of the pedicle, we have been able to make the RITA graft reach any segment of the LAD. In fact, we have not experienced any true technical contraindication for the use of RITA to LAD.
With increasing experience and with an eye to data suggesting the excellent outcome of the pedicled RITA graft to LAD [8, 20], we are now using this combination in an increasing rate reaching 87.6% of all the pedicled RITA grafts in our institution. We also believe that the pedicled RITA graft to LAD has a theoretical anatomical advantage, as it constitutes an excellent linearity and uniformity in direction with the targeted LAD (Figs 1, 2, and 3).
Because of the lack of evidence from a randomized clinical trial that would show the advantage of the skeletonization technique over the wide-pedicle technique in harvesting the ITA grafts, we kept our practice of ITA harvest as a wide pedicle.
One major concern about the more extensive use of pedicled RITA to LAD is the anterior retrosternal cross-over route, which poses a potential risk of damage of the artery during repeat sternotomy. Another concern arises from the possibility of easy aortic cannulation and cross-clamping in case of an emergent reoperation. In a previous experience with 11 patients undergoing reoperation with patent retrosternal RITA grafts crossing the midline, one graft (9%) was damaged and then successfully repaired [29]. Incorporating the retrosternal RITA into polytetrafluoroethylene graft was proposed as an additional safeguard for reoperations [11]. However, the technique had the disadvantages of inability to control bleeding from the RITA branches and the risk of graft kinking at the edges of the rigid material. We still believe that the risk of injury of the RITA graft in case of reoperation remains minimal, provided that the RITA graft is covered by surrounding tissues including: the thymus, pleura, and pericaridium, as in our routine practice [8]. Although we have not yet faced a redo operation with RITA graft to LAD, we believe that those maneuvers should help to separate the sternum from the RITA pedicle and therefore reduce the risk of injury.
Morbidity and mortality in the present study compare favorably to recently reported series of consecutive RITA grafts to LAD performed on-pump [10]. The majority of the patients (91%) in this series were operated on using the OPCAB technique. We believe that this makes the process of evaluating the lengths of the ITA conduits easier, particularly when dealing with large hearts. It is not surprising to note the relatively low incidence of postoperative neurologic complications, as we believe that this is a potential advantage of using bilateral pedicled ITA grafts in minimizing aortic manipulation.
One limitation of the study is the lack of an objective evaluation of the RITA-to-LAD flow by functional provocative tests such as echo Doppler or stress myocardial scintigraphy, which would provide a substantial evidence of the advantage of this technique. Other limitations of the study are the small number of patients who underwent angiography, as well as the lack of mid- and long-term follow-up that are needed to make definitive conclusions about the efficacy of the pedicled RITA graft to LAD.
In conclusion, despite certain limitations, this study shows that the use of the pedicled RITA graft to the LAD artery provides a good early clinical and angiographic outcome. The patency rate of 100% of the pedicled RITA grafts to LAD in this study compares favorably to those in other series [8, 10, 20], and suggests that the pedicled RITA graft to the LAD artery is a good alternative to the pedicled LITA graft to the LAD artery.
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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