Ann Thorac Surg 2003;76:2013-2016
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Our experiences for off-pump coronary artery bypass grafting to the circumflex system
Tomoaki Suzuki, MDa*,
Manabu Okabe, MD, PhDa,
Fuyuhiko Yasuda, MD, PhDa,
Yoichiro Miyake, MDa,
Mitsuteru Handa, MDa,
Takazumi Nakamura, MD, PhDb
a Kochi Municipal Hospital, Kochi, Japan
b Izumino Hospital, Kochi, Japan
Accepted for publication June 25, 2003.
* Address reprint requests to Dr Suzuki, Department of Cardiovascular Surgery, Kochi Municipal Hospital, 1-7-45 Marunouti, Kochi 780-0850, Japan
e-mail: suzukit{at}bronze.ocn.ne.jp
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Abstract
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BACKGROUND: Complete revascularization has been difficult in off-pump coronary artery bypass grafting (OPCAB). Hemodynamic deterioration often prevents access to the circumflex territory. This study presents instrumentation for accessing the circumflex territory, and our clinical experience.
METHODS: From August 1999 through December 2002, 140 patients underwent OPCAB via sternotomy in our institution. The 114 requiring reconstruction of the circumflex artery are the subjects of this study. There were no exclusion criteria. A series of techniques and instruments were developed to provide access to the circumflex area while hemodynamic stability was preserved, including the left pericardial traction technique, compression of the right pericardium, a right sternal retractor, and a type of shunt tube.
RESULTS: Patients received an average of 3.2 grafts (range, 2 to 6). Complete revascularization was achieved in 95% of the cases. Complications included respiratory insufficiency (0.8%), renal dysfunction (7%), and sternal wound infection (0.8%). Blood transfusions were required in 10 patients (8%). No patient suffered perioperative myocardial infarction or stroke. No operation was converted to cardiopulmonary bypass. There was no operative death. Predischarge angiography demonstrated a 99% patency rate.
CONCLUSIONS: With our techniques and instruments, off-pump coronary revascularizaion of the circumflex area may be performed safely to achieve complete revascularization. Early clinical results are excellent, but long-term longitudinal follow-up is required to assess the future effectiveness of OPCAB procedure with our techniques.
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Introduction
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Off-pump coronary artery bypass grafting (OPCAB) has been gaining acceptance among cardiovascular surgeons because it eliminates problems associated with cardiopulmonary bypass (CPB) [1–7). However, complete revascularization cannot be achieved in every patient by OPCAB as hemodynamic deterioration can occur during positioning and stabilization of the heart and snaring of the coronary artery. Attempts at revascularization in the circumflex coronary artery territory often results in hemodynamic compromise [8–11). Thus, accessing the circumflex (CX) system, without compromising hemodynamic stability, is a crucial step towards complete revascularization by OPCAB. We have developed techniques and instrumentation that permit complete revascularization by OPCAB in virtually all patients. In this article, we describe our methods and instruments for exposing the circumflex territory and present the results of an uncontrolled series of patients who underwent circumflex reconstruction by OPCAB.
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Material and methods
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From August 1999 through December 2002, 140 patients underwent OPCAB grafting via sternotomy in our insti-tution. The 114 (81.4%) patients who required revascularization of the circumflex artery are the subjects of this study. Minimally invasive coronary artery bypass grafting (CABG) cases and emergent cases were not included in this material. There were 81 men and 33 women, aged 45 to 82 years (mean, 67.1 ± 8.7 years) (Table1).
We performed OPCAB for all elective CABG, including patients with unstable angina: there were no exclusion criteria.
Anesthetic management
Premedication consisted of intramuscular midazolam (0.04 mg/kg). A standard anesthetic technique was used for all patients. The induction of anesthesia was achieved with fentanyl citrate (10 to12 µg/kg), thiopental (3 to 5 mg/kg), and vecronium bromide (0.1 mg/kg). Anesthesia was maintained with fentanyl, propofol (2 to 3 mg/kg), and low concentrations of sevoflene as necessary. Anticoagulation was achieved with heparin (1 mg/kg) after the internal thoracic artery (ITA) graft was harvested. The activated clotting time was maintained at 
250 seconds. Heparin was reversed with protamine after completion of the anastomoses.
Standard intraoperative monitoring techniques were used. Pulmonary artery floatation catheters were used routinely and they provided continuous evaluation of cardiac output. Transesophageal echocardiography was not used routinely. Red blood cell saving devices were used. A standby without a primed CPB circuit was held in abeyance for all cases.
Operative technique
All procedures were performed through a median sternotomy. The conduits (one or both ITAs, the radial artery, right gastroepiploic artery (RGEA), and saphenous vein) were harvested and skeletonized. Pericardiotomy is essential to preserve hemodynamics stability while exposing the circumflex territory. Following is our technique: After midline pericardiotomy, the left side of the pericardium is peeled away from the pleura and two transverse left pericardiotomies are created. First, the left side of the pericardium is incised from the apex to the back of the pericardial sac to the anterior of the phrenic nerve, in order that it not be injured. The other pericardiotomy is at the level of the left atrial appendage. The right side of the pericardium is incised longitudinally around the superior vena cava (SVC). This maneuver prevents the SVC from being compressed by the pericardium and prevents disruption of venous return when the heart is lifted. Finally, a vertical pericardiotomy is created and carried out toward the inferior vena cava (IVC) at the diaphragmatic surface. The incised left side of the pericardium is pulled up and sutured to the skin, and retracted by sternal retractor. Our sternal retractor is our own design, and elevates the right sternum to create a free space beneath it. Furthermore, the right side of the pericardium is compressed down between the right upper and lower pulmonary veins by a pericardial retractor that we designed. The pericardial retractor is fixed by the surgical arm that is fixed on the operating table (Figs 1, 2, and 3).
As a result, the cardiac base is rotated right side down and left side up and the apex moves into the free space beneath the right sternum. Placing the patient in the right decubitus Trendelenburg position improves
exposure of the circumflex area. We also use the deep pericardial sutures in conjunction with our techniques in cases with cardiomegaly or a too deep pericardial sac.
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Fig 1. (A) Our sternal retractor and right pericardial retractor. The pericardial retractor is fixed with the surgical arm that is fixed on the operating table. (B) The retractor for compressing the right side of the pericardium.
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Fig 2. The surgical view with our technique. The cardiac apex moves into the free space beneath the right sternum without being compressing.
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Fig 3. (1) The left side of the pericardium is peeled and separated away from the pleura. (2) The left side of the pericardium is pulled up and sutured to the skin. It makes the left side cardiac base rotate up. (3) The right sternum is lifted up by the sternal retractor, which we originally designed, and the result in the free space is made beneath the sternum. (4) The right side of the pericardium is compressed down between the upper and lower pulmonary veins by the pericardium retractor, which we originally designed. It makes the right-side cardiac base rotate down and the apex move into the free space beneath the right sternum.
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We use a suction-type mechanical stabilizer (Octopus 3, Medtronic, Minneapolis, MN) to immobilize the target coronary artery. Soft silicon loops are used to perform the coronary occlusion test and control coronary blood flow. Ischemic preconditioning was performed only if hemodynamic deterioration occurred during test occlusion of the coronary artery. Intracoronary shunt tubes were used routinely in all target vessels. These shunts create a bloodless surgical field, assure distal coronary blood flow, and provide hemodynamic stability during anastomosis. Our shunt tube (JMS Bypass Tube, JMS, Hiroshima, Japan) was designed with a very flexible shaft that makes it easy to insert and remove without intimal injury. The JMS bypass tubes are available from 1.25 mm to 2.5 mm in 0.25 mm increments. The distal anastomosis was performed using 8-0 polypropylene by a standard technique.
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Results
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An average of 3.20 ± 0.31 grafts per patient (range, 2 to 6 grafts per patient) were performed. The total number of distal anastomosis was 365, and sequential anastomosis was 42 (two anastomoses in 39 patients and three in 3 patients). The left internal thoracic artery (LITA) was used in 111 (97%) patients, the right internal thoracic artery in 28 (25%, in situ graft in 23, free graft in 5), radial artery in 72 (63%), RGEA in 41 (36%), and the saphenous vein in 48 (42.5%). The grafted vessel was the left anterior descending artery (LAD) in 97% of patients, a diagonal branch in 34%, the oblique marginal (OM) in 65%, the posterior descending artery (PDA) in 78%, the posterolateral branch in 69%, and the right coronary artery (RCA) in 8%. Complete revascularization was achieved in 108 (95%) patients. Seven patients experienced hemodynamic deterioration, which occurred during snaring of the coronary artery (LAD, 3; CX, 2; PDA, 2). One patient developed frequent ventricular premature contraction during test occlusion of the LAD. The other patients developed hemodynamic deterioration as decrease of systemic pressure and cardiac output and as increase of pulmonary pressure and right atrial pressure. However, hemodynamic stability was achieved in all cases, after ischemic preconditioning and prompt insertion of the coronary shunt tube. No patient was converted from off-pump to on-pump. The length of stay in the intensive care unit was 1 day in 112 patients and 2 days in 2 patients. Only 10 patients (8.7%) needed blood transfusions.
Morbidity and mortality
No patient suffered low cardiac output or perioperative myocardial infarction. A sternal wound infection occurred in one patient (0.8%). Respiratory insufficiency necessitating prolonged (> 24 hours) respiratory support occurred in one patient (0.8%), new renal dysfunction (serum creatinine > 2.0 mg/dL) that did not require hemodialysis occurred in 3 patients (2.5%), and no patient had a stroke. There was no operative or hospital death. Postoperative angiography was performed in 113 (99%) patients before discharge (1 to 2 weeks after the operation). Of 376 anastomoses studied, 370 were patent.
Graft occlusion was documented in 2 cases; in 1 case, the SVG was occluded at the anastomotic site to the RCA and, in 1 case, the sequential RGEA graft was occluded at the side-to-end anastomotic site to PDA. Graft stenosis occurred in 4 cases. In 2 cases, SVG to PDA and to OM showed stenosis of the anastomotic site, in the other 2 cases, graft stenosis occurred at the side-to-end anastomotic site of the sequential SVGs to OM–PL and to midRCA–PDA.
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Comment
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As interest in OPCAB surgery has grown the technology supporting it has matured. Refinements in the mechanical stabilizer, especially the suction type (Octopus series Medtronic, Minneapolis, MN) provide a very stable surgical field with minimum hemodynamic change [12]. The deep pericardial suture technique is very effective for providing to the lateral and posterior walls of the heart. Lima [13] first described a method employing a series of sutures to expose the circumflex vessels on the beating heart. With greater experience, the deep pericardial suture technique was modified and is now performed universally [14]. Bergsland and colleagues [15] modified the Lima sutures into a "single suture" technique and documented the simplicity and effectiveness of this method. Ricci and colleagues [16] reported a single suture technique with vaginal tape. This is very simple and useful to expose all areas of the heart without the other instrument. However, this maneuver sometime compresses the heart by the vaginal tape. The point of our technique is to expose the circumflex area without compressing the heart. Our technique, making a free space beneath the right sternum by elevating the right sternum and compressing the right side of pericardium, is very effective for comfortable contraction for the right ventricle without compressing.
We have developed several devices and techniques to improve the quality of the surgical field when accessing the circumflex territory. Rotation of the cardiac base, right side down and left side up, creates wide and stable exposure of the circumflex territory. The incised left side of the pericardium traction technique we presented effectively exposes the circumflex area in conjunction with the deep pericardial suture technique, even in case of cardiomegaly. Compression of the right side of the pericardium by the pericardial retractor enhances rotation of the cardiac base. Finally, the right sternal retractor creates a free space beneath the right sternum that allows the heart to be displaced without compromising contraction.
The coronary shunt tube prevents transient myocardial dysfunction during OPCAB [17]. It maintains coronary perfusion, creates a bloodless surgical field, and prevents "back walling" while creating the anastomosis [18]. Hemodynamic deterioration can occur during snaring of the coronary artery, with either the LAD or the circumflex artery. Therefore, we routinely use a coronary shunt tube in all target vessels. Occasionally it can be very difficult and risky to insert the shunt tube into a coronary artery that is calcified, narrow, or serpentine. We developed a coronary shunt tube that is quite flexible, facilitating insertion and removal without coronary injury. We have never been unable to insert or remove a shunt, nor has any coronary artery been injured through shunt use.
The important factors in achieving stable hemodynamics during circumflex artery anastomosis are as follows: (1) the cardiac base should be rotated right side down and left side up; (2) a free space should be created beneath the right sternum to allow displacement of the heart; (3) systemic and pulmonary venous return should not be impeded; and (4) coronary blood flow should be maintained using a coronary shunt tube.
Routine complete revascularization in all patients by OPCAB surgery is the goal of surgery for myocardial ischemia. The technique presented here allows surgeons easy access to the circumflex territory.
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References
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Abstract
Introduction
