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Ann Thorac Surg 2004;78:1441-1445
© 2004 The Society of Thoracic Surgeons
a Pensacola Heart Institute, Pensacola, Florida, USA
Accepted for publication August 28, 2003.
* Address reprint requests to Dr Vassiliades, Division of Cardiothoracic Surgery, Emory University School of Medicine, 1365A Clifton Rd, NE, Atlanta, GA 30322, USA
thomas_vassiliades{at}emoryhealthcare.org
Abstract
PURPOSE: To evaluate the feasibility of performing multivessel off-pump surgical revascularization without manipulation of the thoracic cage.
DESCRIPTION: The technique consists of bilateral thoracoscopic internal mammary artery harvesting followed by a nonrib-spreading, muscle-sparing opening in the soft tissue of the thorax. An endoscopic cardiac positioner and stabilizers exposes and steadies the target arteries beneath a small opening. Anastomoses are constructed off-pump through the natural width of the intercostal space without the need for rib spreading.
EVALUATION: Fifty-two patients underwent all-arterial, off-pump revascularization through incisions avoiding manipulation of the thoracic skeleton. The mean number of grafts per patient was 2.2 ± 0.4. Transit time flow measurements verified graft patency before closure in all cases. The mean operating time was 4.4 hours (range, 3.4 to 5.6). Hospital length of stay was 2.6 ± 1.9 days. There was no early or late mortality. Postoperative angiography performed in 63.8% of the grafts (74 of 116) revealed an overall patency rate of 98.6%.
CONCLUSIONS: A grafting approach that avoids any manipulation of the thoracic skeleton offers significant patient value and may not be limited to single-graft cases.
| Doctor Vassiliades discloses that he has a financial relationship with Computer Motion, Inc.
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One of the goals of the minimally invasive surgeon is to minimize the trauma of the incision. Recent reports of the endoACAB (endoscopic atraumatic coronary artery bypass) procedure demonstrated that by avoiding manipulation of the musculoskeletal component of the thoracic cavity, surgical revascularization could be achieved without significant trauma [1]. Unfortunately, the majority of these procedures were limited to single-vessel disease (left anterior descending artery [LAD]) situations or in conjunction with a catheter-based intervention (hybrid procedure). Extending the endoACAB for multivessel grafting would greatly expand the utility of this approach and afford significant patient value. This report provides our early experience of multivessel off-pump bypass grafting with preservation of the thoracic skeleton (multivessel endoACAB).
Technique
The technical details of the endoscopic atraumatic coronary artery bypass for single-vessel disease have been previously reported [2, 3]. In the case of multivessel grafting, bilateral, rather than unilateral, thoracoscopic internal mammary artery harvesting is usually performed. The patient is intubated using a double-lumen endotracheal tube and single-lung ventilation is utilized to alternate deflation of the left or right lung during progressive phases of the internal mammary artery dissection. In the majority of cases, the ports are placed on the patient's right side for two important reasons. The right side allows more posterior placement of the ports as opposed to the left side, where the heart will be in the direct line between the skin entrance point and the left internal mammary artery. Therefore, the more posterior position on the right affords the surgeon a more favorable approach angle for the dissection. Additionally, an approach from the right also allows the surgeon to perform an extensive right vertical pericardiotomy that is needed to allow complete displacement of the heart into the right hemithorax (Fig 1). Specifically, the ports are placed in the right third (grasper), fifth (5-mm endoscope), and seventh (electrocautery) intercostal spaces between the mid and anterior axillary lines. Precise endoscope movement is made possible by employing the AESOP robotic arm (Computer Motion, Goleta, CA). Before beginning the internal mammary artery dissection, the mediastinal attachments from the heart to the underside of the sternum are divided and both pleural spaces are opened widely, essentially created one single pleural cavity. Carbon dioxide insufflation at 8 mm Hg to 10 mm Hg aids significantly in providing additional working space by increasing the distance between the anterior surface of the heart and the sternum up to 4 cm. The endoscopic instruments (through the right-sided ports) are advanced across the midline to harvest the left internal mammary artery first. During this phase of the procedure the right lung is inflated and the left lung deflated. To perform the right (ipsilateral) internal mammary artery harvest, the instruments are pulled back into the right hemithorax, deflating the right lung and inflating the left lung. The pericardium is then opened thoracoscopically and the coronary anatomy clearly delineated. In addition to the standard midline pericardiotomy, a long right vertical pericardiotomy is performed. The line of incision is perpendicular to the midline opening, parallels the right hemidiaphragm (2 to 3 cm from its attachment to the diaphragm) and is carried down to the right phrenic nerve (Fig 1). By opening the pericardium on the right side, the heart can be rotated into the right hemithorax (along the axis of the vena cavae) thereby exposing the posterolateral wall through the left anterior chest opening.
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A thoracoscopic version of an open (sternotomy) cardiac positioner is employed to position the heart under the nonrib-spreading thoracotomy. During our initial experience with grafting coronaries beyond the anterior wall, several prototypes were tested including the Starfish NS (Medtronic, Minneapolis, MN; Fig 3), and a modified Expose positioner (Guidant, Santa Clara, CA). The devices consist of a suction head that can detach from the positioning arm. The positioning arm is passed through a port opening in the chest, the suction head is introduced into the chest through the small thoracotomy, and the device is assembled in the chest (Fig 4). Once the desired target vessel is positioned under the incision, the external portion of the positioner arm is attached to a bed-rail mounted attachment. Cardiac stabilization is then accomplished by a similar technique using an externally mounted (to the bed rail) rigid or flexible stabilizer arm passed through a port and then internally connected to a stabilizer device. Using the compression technique, a rigid 6-mm rod is connected to a 3-cm square metal plate (endoACAB Computer Motion, Goleta, CA) or plastic compression plate (Immobilizer; Genzyme, Cambridge, MA) with a window for the coronary artery and holes for silastic occlusion tapes. Prototypes using the suction method included the Octopus 3 and Octopus 4 stabilizers with detachable suction heads (Medtronic), as well as the Axius and Acrobat systems with a detachable footplate employing suction (Guidant). Regardless of the stabilization technique, an intracoronary shunt can be used as in any sternotomy case.
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Preoperative data
Between July 2001 and January 2003, 52 of 59 patients consented successfully underwent a multivessel endoscopic coronary artery bypass operation. During this same period, 61 patients underwent a single-vessel endoACAB and 182 patients underwent a multivessel CAB through a sternotomy, performed by the same surgeon (T.A.V.). The mean age for the 52 multivessel endoACAB patients was 63.4 years, with 46 male and 6 female patients. The mean body mass index (BMI) was 30.9 (range, 26 to 35). The mean preoperative left ventricular ejection fraction was 48.9% (range, 25 to 70%). Before operation, all patients were asked to undergo a postoperative study to assess graft patency.
Operative data
The mean number of grafts per patient was 2.2 ± 0.4 with specific data outlined in Figure 5. Transit time flow measurements (Medi-Stim, Medtronic, Minneapolis, MN) verified graft patency before closure in all cases. Mean graft flow was 45 ± 28 mL/min. The mean operating time was 4.4 hours (range, 3.4 to 5.6). Mean intraoperative blood loss was 547.5 ± 370.4 mL. There was no significant reduction in the mean arterial blood pressure or cardiac index during grafting of the LAD or diagonal coronary arteries. During grafting of the posterolateral vessels, a modest reduction in the mean arterial blood pressure and cardiac index was observed. While the reduction in cardiac function was not significant clinically, this was not specifically studied. Seven patients (8.8%) were converted to sternotomy owing to inability to expose the target coronary artery (3 patients), inadequate mammary flow (1), an intramyocardial vessel (1), significant chest wall bleeding (1), and global ischemia causing hypotension (1). One patient was converted to an on-pump grafting procedure.
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Comment
This report represents our early experience with extending the endoACAB operation to multivessel capability. A primary determinant of our initial success was patient selection: a body mass index of greater than 35, a massively enlarged heart, and poor left ventricular function were contraindications to this technique. We are encouraged that simple modification of sternotomy-based cardiac positioners and stabilizers was successful. Through a single 6-cm nonrib-spreading incision, grafts can be constructed to the LAD, diagonal, ramus intermedius, and obtuse marginal arteries. We are still in our early experience with grafting the posterolateral vessels through this limited access approach (10 grafts to the ramus intermedius and 5 to the obtuse marginal). As both the technique and the tools improve, however, we would expect this to become as routine as grafting the anterior vessels. There were 17 patients who presented with left anterior descending and proximal right coronary artery disease. In most of these cases (11 of 17), it was possible to perform both anastomoses (left internal mammary artery to LAD and right internal mammary artery to the right coronary artery) through a single right-sided incision. The right coronary artery was grafted through the fourth or fifth intercostal space on the right, and then the heart was rotated into the right pleural space where the LAD was positioned under the same incision. In 6 patients, two (bilateral) nonrib-spreading incisions were required. We have yet to solve the mechanics of grafting the posterior descending or posterolateral branch of the right coronary with this approach.
Our success with "off-the-shelf" devices serves only as proof of concept. To be able to truly expand this approach to the majority of patients and for the majority of cardiac surgeons, devices specific to closed chest situations need to be developed. The endoACAB approach demonstrates that endoscopic and open techniques can be blended and still satisfy our goals of minimizing patient trauma. Performing an off-pump anastomosis under direct vision remains technically easier and more reproducible, given the current limitations of endoscopic visualization systems [4, 5]. Such a "direct" approach also overcomes the challenges of designing strong, articulating cardiac positioners and stabilizers that have to fit through small ports. The "two-piece" approach to equipment allows the design and manufacturing of such equipment to be straightforward. In summary, advancing the endoACAB to multivessel capability will offer significant value, but only if we retain the philosophy of minimizing trauma to the thoracic cavity. This can only be achieved by maintaining, at the very least, complete integrity of the thoracic skeleton; otherwise there is little patient value beyond that of sternotomy.
Disclosures and Freedom of Investigation
The thoracoscopic equipment including the endoscopic cardiac positioners and stabilizers were purchased by Sacred Heart Hospital. The design of this review, including data collection, analysis, and interpretation, was free of outside interests. Doctor Vassiliades either currently or in the recent past has had consultant relationships with Genzyme Corp; Medtronic Corp; Computer Motion, Inc; and Guidant Corp.
Disclaimer
The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
References
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