Ann Thorac Surg 2000;70:1063-1065
© 2000 The Society of Thoracic Surgeons
Supplement: cardiothoracic techniques & technologies
Minimally invasive direct coronary artery bypass grafting: intermediate-term results
Thomas A. Vassiliades, Jr, MDa,
Edwin W. Rogers, MDa,
James L. Nielsen, MDa,
James L. Lonquist, MDa
a Pensacola Heart Institute of Sacred Heart Hospital, Pensacola, Florida, USA
Address reprint requests to Dr Vassiliades, Cardiothoracic Surgical Associates of NW Florida, 5147 North Ninth Ave, Suite 401, Pensacola, FL 32504
e-mail: vassiliades{at}pol.net
Presented at the Sixth Annual Cardiothoracic Techniques and Technologies Meeting 2000, Ft Lauderdale, FL, Jan 27–29, 2000.
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Abstract
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Background. Intermediate- and long-term clinical outcome and graft patency in minimally invasive direct coronary artery bypass grafting (MIDCABG) procedures remain a concern.
Methods. Over a 13-month period, 66 MIDCABG procedures were performed utilizing robotic-assisted internal mammary artery (IMA) harvesting and direct CABG through a 5-cm thoracotomy without cardiopulmonary bypass. Clinical follow-up was obtained on all patients. Graft patency was assessed in 61 of 66 consecutive patients 6 months (range 2 to 15 months) postoperatively. Group I consisted of 45 patients who underwent IMA angiography and group II consisted of 16 patients who underwent both a nuclear stress test and transthoracic Doppler examination. All group II patients had abnormal preoperative nuclear stress tests for comparison.
Results. To date, all 66 patients are alive. Graft patency rates in the two groups were 97.8% (45 of 46 grafts in 45 patients) in group I and 100% (15 of 15 grafts), with one indeterminate study, in group II. The overall patency rate for the entire study group was 98.3% (60 of 61 grafts). Sixty-two of 66 (93.9%) patients were able to return to their normal level of activity within 3 weeks.
Conclusions. This study demonstrates that the MIDCABG with thoracoscopic IMA harvesting can achieve effective intermediate-term revascularization and an acceptable clinical outcome.
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Introduction
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Concerns still remain regarding patency rates and clinical outcome for patients undergoing minimally invasive direct coronary artery bypass grafting (MIDCABG) procedures [1, 2]. The early experience of MIDCABG procedures utilizing chest wall retractors to achieve adequate exposure for internal mammary artery (IMA) harvesting cast significant doubt on the advantages of this procedure over the conventional sternotomy [2]. Concurrently, the techniques for performing off-pump coronary artery anastomoses were being learned in the setting of limited exposure. As a result, many surgeons abandoned MIDCABG as compromising the excellent results of conventional CABG. In this study, we reviewed patients who underwent MIDCABG procedures utilizing a totally endoscopic, robotically assisted IMA harvest method. A follow-up study was then conducted to assess intermediate-term patency rates and patient satisfaction.
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Patients and methods
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Patients
Between February 1998 and April 1999, 66 consecutive patients underwent a MIDCABG operation utilizing a thoracoscopic technique of IMA harvesting with robotic assistance. The mean patient age was 61.2 years (range 31 to 81 years). Clinical presentation of NYHA classification consisted of class I (47.0%), class II (40.9%), class III (7.6%), and class IV (4.5%). Sixteen (24.2%) patients had a preoperative myocardial infarction. Twenty-seven patients (40.9%) had a prior percutaneous transluminal coronary angioplasty and 3 patients (4.5%) a prior CABG. Overall preoperative left ventricular function consisted of 38 patients with an ejection fraction of 50% or better, 24 patients in the 30% to 50% range, and 4 patients with an ejection fraction below 30%.
Technique
The technique used in all operations consisted of single-lung ventilation and carbon dioxide insufflation. The IMA was then harvested as a pedicled graft using the electrocautery on a low setting. A total of three small stab wounds were used for the harvest of the IMA. A 5.5-mm port (Genzyme Surgical Products, Cambridge, MA) was used for the 5-mm scope placed in the fifth intercostal space along the anterior axillary line. A small stab wound was used for the cautery and was placed in the third intercostal space also along the anterior axillary line. Another stab wound was used for a grasper and was placed in the seventh intercostal space along the nipple line. Control of the thoracoscope was accomplished using a voice-activated robotic arm (AESOP, Computer Motion, Goleta, CA). The IMA was harvested from its subclavian artery origin to the sixth rib. After completion of the IMA harvesting phase, the pericardium was opened and the target vessel was identified. A 5-cm incision was then made and the chest was entered usually through the fourth intercostal space. The patient was then heparinized to an activated clotting time (ACT) of more than 400. Distal target stabilization was achieved using a device that integrates stabilization with occlusion (Genzyme Surgical Products, Cambridge, MA). Coronary occlusion was achieved by silastic tapes (Quest Medical, Allen, TX) in conjunction with a disposable platform (Genzyme). A Medtronic Clearview blower/mister (Medtronic, Minneapolis, MN) at 3-L flow or less was also used for keeping the field clear. The anastomosis was sewn with either 7-0 or 8-0 Prolene (Ethicon, Somerville, NJ) suture. An audible Doppler was used to assess diastolic flow. Selected patients underwent intraoperative angiography [3]. The ACT was then fully normalized with protamine. A 22F to 28F pleural tube was inserted in the camera port site. The intercostal spaces were injected with 1% papivacaine with epinephrine. After closure, the patient was usually extubated in the operating room. Aspirin was administered rectally to all patients 4 hors after operation.
Study protocol
We reviewed results from the time of operation to the date of the patient’s final postoperative visit at 6 weeks. Subsequent follow-up of these patients consisted of completion of a satisfaction survey and a personal interview. Information was obtained on readmissions, reinterventions, recurrence of angina, and level of function. After approval from our local institutional review board (April 13, 1999), each patient was asked to submit to an angiogram to evaluate the graft and anastomosis (group I). Patients who declined the angiogram were asked to undergo a nuclear stress test, using technetium Tc99m sestamibi (Dupont, Billerica, MA) or thallium, similar to their preoperative study, as well as a transthoracic Doppler examination of the IMA graft (group II).
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Results
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Thirty-day outcome
The mean harvest time of the IMA was 58.2 minutes (range 35 to 110 minutes) and the mean total operating time was 162 minutes (range 118 to 282 minutes). There were no iatrogenic injuries to the IMA. Three patients were converted to a sternotomy because of deep intramyocardial left anterior descending coronary artery (LAD) vessels (n = 2) and inadequate IMA size (n = 1). They underwent uneventful CABG through a conventional sternotomy and had an uncomplicated postoperative course. These patients were not included in this study. Sixty-one patients underwent a left internal mammary artery (LIMA) to LAD procedure, 4 patients underwent a right internal mammary artery to right coronary artery procedure, and 1 patient had LIMA to LAD and saphenous vein graft to diagonal (proximal to the LIMA). The mean coronary occlusion time was 11 minutes (range 6 to 21 minutes). Two patients with severe left ventricular dysfunction required dobutamine during the operation. Fifty-eight patients (88%) were extubated in the operating room. Table 1 lists the in-hospital clinical outcomes and complications. There were no in-hospital deaths, myocardial infarctions, or neurologic events.
Interview and survey results
All 66 patients participated in the follow-up interview and satisfaction survey. The questions and the results are listed in Table 2. The mean follow-up period was 23.2 weeks (range 9 to 56 weeks). During this time there were no deaths, cardiac-related hospital admissions, or readmissions. There have been no wound infections, myocardial infarctions, or neurologic events. Four patients had been seen in the emergency department for pulmonary-related problems.
Follow-up study results
Five patients declined to participate in a follow-up study because of their significant distance from the study site (n = 4) and family illness (n = 1). Sixty-one of 66 patients consented to undergo a follow-up study. The mean time interval from operation to study was 5.8 months (range 9 to 56 weeks). Forty-five patients (group I), with a total of 46 grafts, underwent IMA angiography through the radial, femoral, or brachial artery. The anastomoses were classified using the FitzGibbon [4] grading system of postoperative angiography as either grade A (unlimited runoff) for 42 patients, grade B (stenosis reducing caliber of proximal or distal anastomosis or trunk to less than 50% of grafted coronary artery) for 3 patients, or grade O (occlusion) for 1 patient. The 3 patients with grade B anastomoses subsequently underwent nuclear stress tests, which did not indicate ischemia. The patient with a grade O anastomosis actually had a patent "string-sign" of his entire distal LIMA graft but this graft was considered occluded in this study. The patency rate for the group I patients was 97.8% (45 of 46 patients). The remaining 16 patients (group II) in the study underwent both a nuclear (sestamibi or thallium) and a transthoracic Doppler. The systolic-to-diastolic peak velocity ratio and diastolic flow time interval was used to assess the grafts. All of these patients had previously undergone preoperative stress tests, which were positive. The same test was performed postoperatively so a comparison could be made upon interpretation. Fifteen patients who had had positive tests preoperatively had negative stress tests during follow-up. Additionally, the transthoracic Doppler examinations confirmed patent grafts. One patient had an equivocal postoperative stress test and a patent graft by Doppler examination. The patency rate for the group II patients was 100% with one indeterminate study. The overall patency rate for the entire study group (groups I and II) was 98.3% (60 of 61 patients) with one indeterminate study.
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Comment
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Since its introduction in 1996 [5], the MIDCABG procedure has undergone significant technical modification. Many of the early procedures were performed utilizing a direct vision technique of harvesting the IMA, often with available equipment not specifically designed for the procedure. Later, retractors designed for direct vision IMA harvest became popular, but resulted in significant chest wall trauma and subsequent long-term negative effects on the patient’s quality of life. Concurrently, new techniques for performing off-pump coronary anastomoses, still in their infancy, were being learned in the setting of very limited exposure. As a result, many surgeons abandoned the new techniques and cast significant doubt on the ultimate value of the MIDCABG procedure. Many continue to doubt the advantages of the MIDCABG procedure. We, and others, embraced early the technique of using thoracoscopy as a more precise and less traumatic method to harvest the IMA. Additionally, the amount of information that is learned through the endoscope about the anatomy of the heart and chest wall is extremely useful in setting up a straightforward and successful anastomosis. This advantage has been appreciated. Although more technically demanding to learn, we accept the endoscopic approach as the method of choice. With the addition of a voice-activated robotic-controlled endoscope, this procedure has become less technically demanding and more efficient. Additionally, the significant improvements in techniques for performing off-pump coronary anastomoses through a sternotomy have also provided improvements in the MIDCABG procedure.
Although the assessment of the graft early in the postoperative course is important, we did not routinely perform intraoperative angiography. The procedure is usually straightforward, but can add 30 to 40 minutes to the total operating time. Additionally, the minor irregularities that are occasionally seen with angiography in this setting are difficult to interpret [6]. Admittedly, the Doppler has also been shown to be unreliable [7]. One must have confidence in the technical quality of the anastomosis or revise it before the patient leaves the operating room. The average time from operation to angiogram (5.8 months) for the patients in this study was well beyond the interval one would expect to see technical failures. As a result, the patency rate of these patients at this intermediate checkpoint should be closely representative of long-term patency.
The MIDCABG procedure performed with robotic-assisted thoracoscopic IMA harvesting has laid the essential groundwork for the future totally endoscopic bypass procedures that are just now evolving. This study has demonstrated that the MIDCABG procedure can yield excellent clinical outcome and acceptable intermediate-term patency rates.
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Acknowledgments
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This work was supported by a grant from the Regional Heart Institute of Sacred Heart Hospital. We thank John Stewart for his assistance.
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References
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Abstract
Introduction
