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Ann Thorac Surg 1999;67:500-503
© 1999 The Society of Thoracic Surgeons

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Original Articles

Minimally invasive direct coronary bypass versus cardiopulmonary technique: angiographic comparison¹

^a Division of Cardiac Services, St. Charles Medical Center, Bend, Oregon, USA

Accepted for publication July 25, 1998.

Address reprint requests to Dr Lazzara, The Hope Heart Institute, 528 18th Ave, Seattle, WA 98122

	Abstract

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
Background. Studies comparing minimally invasive direct coronary artery bypass grafting (MIDCABG) with techniques using cardiopulmonary bypass (CPB) are needed.

Methods. Sixteen patients underwent single-vessel left internal thoracic artery–left anterior descending (LITA-LAD) MIDCABG through a left anterior thoracotomy, and 10 underwent multivessel bypass grafting that included a LITA-LAD, using CPB. Intraoperative completion angiography was performed on all LITA-LAD bypasses, and graded. One point each was given for: anastomotic patency, pedicle patency, intercostal obliteration, proper placement into the correct native coronary artery, and Thrombosis In Myocardial Ischemia grade III flow.

Results. There were no intraoperative deaths or morbidities. LITA takedown averaged 49 ± 18.6 minutes for MIDCABG and 16 ± 2.0 minutes for CPB CABG (p < 0.05). LITA length did not differ between groups (15.3 ± 1.2 cm for MIDCABG, 14.3 ± 1.08 cm for CPB CABG). Ischemic arrest time was significantly less for the CPB group (13.3 ± 8.3 minutes versus 24.5 ± 9.6 minutes; p < 0.05). Average grade for MIDCABG LITA-LAD was 4.06 ± 0.98 points versus 4.77 ± 0.98 points for CPB LITA-LAD bypass (p = not significant).

Conclusions. Intraoperative completion angiography is feasible and, when combined with a grading system, may facilitate the comparison of MIDCABG with standard techniques.

	Introduction

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
Despite a lack of prospective, clinically directed studies, minimally invasive direct coronary artery bypass grafting (MIDCABG) has become a commonly performed procedure. The standard of care for operative revascularization of the left anterior descending (LAD) artery is use of the left internal thoracic artery (LITA) with cardiopulmonary bypass (CPB) techniques. The inception of MIDCABG at our institution began with the concomitant use of intraoperative completion angiography to insure LITA-LAD anastomotic and pedicle patency and immediate surgical correction of technical problems before patient discharge from the operating room suite [1]. Intraoperative completion angiography has the ability to identify specifically an anatomic or physiologic problem, enabling a focused approach to its correction. In an attempt to develop a comparative grading system to identify and assess the technical pitfalls in beating heart operations, we compared intraoperative angiographic results between LITA-LAD MIDCABG and LITA-LAD using CPB.

	Material and methods

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
No high-risk patients were included in either group. The MIDCABG operations were done during the initial learning curve of the surgeon (RRL).

A total of 26 patients were studied after informed consent was obtained. Sixteen (11 men, 5 women; mean age, 65.8 ± 13.6 years) underwent single-vessel LITA-LAD bypass using MIDCABG techniques as part of an internal review board-approved protocol at St. Charles Medical Center, Bend, Oregon. The technique of MIDCABG has been previously described [2, 3]; it involves performance of a left anterior thoracotomy, harvest of the LITA, and beating heart LITA-LAD bypass using a specialized retractor and epicardial stabilization system (Cardiothoracic Systems, Cupertino, CA). Another 10 patients (9 men, 1 woman; mean age, 68 ± 7.6 years) undergoing elective multivessel CABG that included LITA-LAD bypass using the technique of ischemic fibrillatory arrest and CPB were selected for completion LITA-LAD angiography. Intraoperative angiography was performed through a femoral approach. Femoral access was obtained after anesthesia induction by the surgical team. Angiography was performed by a cardiologist using a digitally based portable angiographic system (OEC Medical Systems, Salt Lake City, UT) that was incorporated into the surgical suite (Fig 1 ). Completion angiography was performed before thoracotomy closure in the MIDCABG patients and after weaning from bypass and complete chest closure in the cardiopulmonary LITA-LAD bypass patients. Views were obtained in straight anterior, right anterior oblique, and left anterior oblique projections. Intraoperative angiography was performed using a femoral artery introducer system (7F USCI No. 07001, C.R. Bard, Inc, Billerica, MA). A LITA catheter (7F No. 010371, C.R. Bard) and a 0.032 in. by 145 cm, 3-mm J guidewire (USCI No. 007042, C.R. Bard) were used to intubate the ITA ostia. Ionic contrast material (350 mg/mL iohexol) (Nycomed, Inc, Princeton, NJ) was used in all patients. Final interpretations were made and dictated by the cardiologist after an independent review of completion angiography results. The initial straight anterior view was used to document pedicle patency and obliteration of intercostal vessels. Subsequent right anterior oblique and left anterior oblique views were used to document distal pedicle and anastomotic patency (less than 50% reduction in luminal or anastomotic diameter in two distinct views), and to determine graded flow from pedicle to LAD, using the Thrombolysis In Myocardial Infarction (TIMI) scoring system, TIMI 0, TIMI I, TIMI II, and TIMI III.

View larger version (103K): [in this window] [in a new window]   Fig 1. Digitally based portable angiographic system used in the surgical suite.

	Results

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
There were no intraoperative deaths or morbidities. There were no cases of ITA dissection. No patient experienced a neurologic event or perioperative myocardial infarction. The mean New York Heart Association functional class was 3.2 for the MIDCABG group and 3.3 for the CPB group. There was no significant difference in ejection fraction between groups (61% MIDCABG and 63% CPB). Significant differences occurred for ITA takedown time (49 ± 18 minutes MIDCABG versus 14.3 ± 2 minutes CPB; p < 0.05) and ischemic arrest time for performance of the LITA-LAD anastomosis (24.5 ± 9.6 minutes MIDCABG versus 13.3 ± 8 minutes CPB; p < 0.05). There was no difference in total mean LITA-LAD grade between the two groups (4.06 ± 0.98 points for the MIDCABG group and 4.77 ± 0.33 points for the CPB group).

Angiographic results led to a 31% intervention rate in the MIDCABG group. None of the patients requiring intervention exhibited clinical evidence of ischemia or hemodynamic compromise. One MIDCABG patient had an anastomosis with a more than 50% stenosis; this patient also had TIMI grade I flow and was converted to a sternotomy. A second MIDCABG patient required conversion for placement of the ITA into a diagonal vessel instead of the LAD, in conjunction with a large patent intercostal vessel. Two MIDCABG patients underwent repositioning of the ITA pedicle through the thoracotomy incision because of a more than 50% angiographic lesion in the pedicle. A single MIDCABG patient underwent angioplasty of the native LAD due to a 70% lesion in the IMA pedicle proximal to the anastomosis, after failure of efforts to correct the lesion by repositioning or lengthening the pedicle. Angiographic follow-up at 6 months in this patient revealed occlusion of the native LAD at the angioplasty site and a patent ITA pedicle and anastomosis.

None of the patients in the CPB group required an intervention; however, 3 patients received less than a perfect score of five points. One patient had patency of a first intercostal vessel, 1 patient had a 50% anastomotic narrowing with TIMI grade III flow that did not result in reintervention, and a single patient had TIMI grade II flow secondary to coronary vasospasm that responded to intracoronary verapamil hydrochloride.

	Comment

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
Newer techniques of beating heart bypass require comparison with established CPB techniques that are considered standard of care. Completion intraoperative angiography for assessment of coronary bypass grafts is a new technique that allows immediate assessment of bypass conduit function [4–6]. The purpose of this small study was limited to determination of its feasibility and use in grading, assessment, and comparison of MIDCABG as a procedure for LITA-LAD bypass with standard techniques. Large comparative studies of MIDCABG with standard LITA-LAD bypass techniques have not been done, nor have studies documenting immediate angiographic results of standard or MIDCABG bypass techniques and their relation to long-term outcomes. In addition, early studies attempting to validate patency rates of MIDCABG report less than 100% angiographic follow-up and do not have control arms using standard LITA-LAD approaches.

The most recent, complete angiographic study of LITA-LAD using CPB techniques is the International Multicenter Aprotinin Graft Patency Experience Trial [7], in which 645 patients undergoing LITA-LAD bypass with CPB techniques had coronary angiography at a mean of 10.9 days postoperatively. The study documented a 91% patency rate (<50% stenosis with normal antegrade flow). Fifty patients (7.8%) had more than 50% stenosis, and occlusion of the LITA was seen in 8 patients (1.2%). Initial studies using immediate intraoperative completion angiography after MIDCABG have documented patency rates between 70% and 87% with total occlusion rates as high as 10% to 15% [1, 4–6].

This study documented one anastomotic problem for a patient in the MIDCABG group. Technical problems were most commonly related to the pedicle (3 patients), with problems also documented in graded flow (2 patients), placement (1 patient), and patent intercostals (1 patient). Immediate angiographic analysis of CPB LITA-LAD techniques also diagnosed a single anastomotic problem, with other points subtracted for a patent intercostal (1 patient), and less than TIMI grade III flow related to spasm (1 patient). An initial conclusion may be that currently available epicardial stabilization devices allow for the performance of an acceptable anastomosis, but that differing ergonomics related to working in a smaller, more confined space result in less than optimal pedicle patency rates that can be improved with experience, technologic advances or reversion to larger, more ergonomically satisfactory, incisions.

Coronary spasm and reductions in graded flow in the absence of anastomotic and pedicle problems, and their relation to short- and long-term function are unknown. However, evaluating flow before exiting the operating room and discovering the physiologic, pharmacologic, and technical factors that can prevent diminished flow are surely important in determining adequate long-term function of bypass grafts.

Patency of intercostal vessels, their size, and their effect on long-term function and flow are unknown and speculative. The ability to document obliteration of all intercostals before operative discharge should have a positive, rather than a detrimental, effect on optimal long-term function [8–11].

Last, the ability to avoid inaccurate placement of bypass conduits is important and at times difficult using MIDCABG techniques. The smaller working space, variations in patient anatomy, and reduction in use of anatomic landmarks because of small incisions may cause inaccurate placement in some patients. Avoiding this potential complication while still in the operating room is clearly important.

The relationship between immediate postoperative completion angiography findings and long-term results is unknown. A single patient in this study had correction of a clearly defined kink in the ITA pedicle when restudied at 6 months (Fig 2 ). It is likely that immediate angiographic results are influenced by conditions that are not present during late angiographic studies. Immediate angiographic findings appear to be related to a dynamic interplay between lung mechanics, the beating heart, technical placement of the pedicle, size and location of the pericardiotomy incision, the effects of epicardial dissection, pharmacologic agents, and other as yet undefined factors that are not present after healing and fixation of the ITA anastomosis and pedicle.

View larger version (105K): [in this window] [in a new window]   Fig 2. Minimally invasive direct coronary artery bypass grafting of left internal mammary artery to the lateral anterior descending. Note kink proximal to patent anastomosis (grade 4). Angiography led to repositioning of pedicle. Correction of the problem was achieved without redoing the anastomosis, and did not require cardiopulmonary bypass.

	Footnotes

Top Footnotes Abstract Introduction Material and methods Results Comment References

 
¹ Doctor Lazzara is a member of the Scientific Advisory Board for, and holds stock options with, Cardiothoracic Systems.

	References

Top Footnotes Abstract Introduction Material and methods Results Comment References

 

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2. Subramanian V.A., McCabe J.C., Geller C.M. Minimally invasive direct coronary artery bypass grafting: two-year clinical experience. Ann Thorac Surg 1997;64:1648-1655.[Abstract/Free Full Text]
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4. Osborne J., Mack M., Scruggs J., Magovern J., Landreneau R. Graft patency rates among patients undergoing minimally invasive-coronary artery surgery. J Am Coll Cardiol 1998;31:70A.
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6. Aliabadi D.G., Pica M.C., Safian R.D., et al. Intraoperative coronary angiography using a mobile fluoroscope to assess graft patency following minimally invasive coronary bypass surgery. Circulation 1997;96(suppl 1):369-370.
7. Berger P.B., Alderman E.L., Schaff H.V. Frequency of early occlusion and stenosis in the left internal mammary artery among patients undergoing CABG through a median sternotomy on conventional bypass: benchmark for the MIDCABG [abstract]. Circulation 1997(suppl 1):681.
8. Patel V., Bailey S.R., O’Leary E., Hoyer M.H. Novel technique for coil embolization of intercostal branch of internal mammary artery graft. Cathet Cardiovasc Diagn 1997;42:229-231.[Medline]
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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Robert R. Lazzara Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lazzara, R. R. Articles by Kidwell, F. E. Search for Related Content PubMed PubMed Citation Articles by Lazzara, R. R. Articles by Kidwell, F. E. Related Collections Related Article