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Ann Thorac Surg 1997;64:110-114
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

A Survey on Minimally Invasive Coronary Artery Bypass Grafting

Divisions of Cardiothoracic Surgery, The Montreal General Hospital, McGill University, Montreal, Quebec, Canada, and The Humane Hospital, Dallas, Texas

Accepted for publication January 15, 1997.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
Background. There is increasing interest in performing minimally invasive coronary artery bypass grafting. To evaluate the current level of acceptance and utility of this procedure a survey of 162 cardiothoracic surgeons was conducted.

Results. Currently only 16% of surveyed surgeons performed more than 10 minimally invasive coronary artery bypass grafting procedures. Most were less than 55 years old and in private practice. The majority predicted that it will be indicated in less than 25% of coronary artery bypass grafting cases and considered minimally invasive coronary artery bypass grafting a modification of existing techniques rather than investigational. Most believed exposure and stabilization of the coronary arteries on the beating heart to be the most challenging part and expressed concern with quality of the anastomosis.

Conclusions. We conclude that minimally invasive coronary artery bypass grafting is rapidly gaining acceptance in younger surgeons as techniques are improved. Despite concerns with adequacy of anastomosis the procedure is not considered investigational and follow-up is not rigorous.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
See also page 114.

Over the past 2 years, there has been rapid adoption and transfer of experimental techniques and observations of minimally invasive cardiac operations into clinical practice. At least 500 patients worldwide have benefited from one technique or another of minimally invasive coronary artery bypass grafting, mitral and aortic valve repair and replacement, and correction of congenital intracardiac defects [1–4]. Coronary artery bypass grafting (CABG), whether primary or redo, is now the most common procedure performed for single-vessel stenosis [5, 6]. Currently, there are at least 30 published abstracts and articles relating to minimally invasive cardiac operations.

Minimally invasive coronary artery bypass (MICAB) grafting is defined as a grafting operation performed through smaller and less painful incisions with or without use of cardiopulmonary bypass. This generalized definition encompasses a variety of access incisions with the most common being an anterior mini-thoracotomy for the left internal mammary artery to left anterior descending (LAD) anastomosis. Inherent in most innovative procedures is an expected divergence in opinion on its acceptability, exact role in coronary artery revascularization, ideal techniques, and anticipated short- and long-term outcomes.

This survey describes how MICAB is currently perceived by practicing cardiothoracic surgeons.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
This survey was conducted by an audience response system at a symposium held in Montreal on July 19–20, 1996. The audience response system was accessible to a random sample of 162 surgeons from a total of 240 who attended the conference. Seventy-four questions were posed after instructions and administration of five test questions to ascertain knowledge of the audience on how to use the system. The nature of this survey is to examine and poll, in a direct noncomparative fashion, the current demographics and attitudes of selected surgeons interested in MICAB. Results are tabulated as absolute numbers and percentages without statistical analysis. This article presents the results of 37 of the most pertinent questions.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
Demographics
Most respondents (92%) were less than 55 years of age. Fifty-six percent of respondents practiced in a private group, 34% in a university setting, and 10% in solo private practice. Sixty percent of surgeons practiced both cardiac and general thoracic surgery with the remaining practicing solely cardiac surgery. Sixty-seven percent had endoscopic experience and 33% had none. Eighty-four percent of surgeons reported they had performed less than 10 cases as primary operator of MICAB procedures, 12% had performed 11 to 50 cases, 1% 51 to 100 cases, and 3% more than 100cases. When surgeons were asked about their trend of MICAB procedures performed over the past 6 months, 28% indicated increasing use, 2% said use was decreasing, 10% reported no change in trend, and 60% stated that MICAB was not used during the past 6 months.

	Technical Issues

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
When surgeons were asked which is more preferable to eliminate to render coronary artery bypass grafting less invasive, 81% stated avoiding cardiopulmonary bypass whereas 19% indicated avoiding median sternotomy (Fig 1). Despite this, 56% of respondents did not believe that a short period of cardiopulmonary bypass was detrimental and should be avoided if possible.

View larger version (19K): [in this window] [in a new window]   Fig 1. . Survey question: "In your opinion, which is more preferable to eliminate?" Answers: (1) median sternotomy; (2) cardiopulmonary bypass.

View larger version (23K): [in this window] [in a new window]   Fig 2. . Survey question: "Which approach do you use for minimally invasive coronary artery bypass grafting?" Answers: (1) partial sternotomy; (2) vertical thoracotomy; (3) left anterior thoracotomy; (4) other.

Fifty-nine percent of respondents believed that harvest of the total length of the mammary artery was required, whereas 41% thought it was adequate to harvest just enough length to reach the LAD. Thirty-one percent of surgeons used a thoracoscope for this procedure and 69% did not. Only 41% believed that inadequate LAD flow attributable to persistence of LIMA collaterals posed a real problem, whereas 59% disregarding this as unimportant physiologically (Fig 3).

View larger version (21K): [in this window] [in a new window]   Fig 3. . Survey question: "Do you think that inadequate left anterior descending flow due to left internal mammary artery collaterals persistence is a real problem?" Answers: (1) yes; (2) no.

When technical questions were raised concerning LAD occlusion for the purpose of anastomosis on the beating heart, 44% of surgeons used Prolene (Ethicon, Somerville, NJ) sutures and snares, 28% used silicone occluders/silicone tape, and 28% neither occluded nor used other technique. Fifty-six percent of surgeons did not believe that coronary artery shunt is essential for safety of MICAB on a beating heart, whereas 42% stated that shunting was only occasionally necessary and only 2% thought this was often necessary.

When asked how the distal anastomosis is performed, 79% stated they used single running sutures, 18% used two running sutures, and 3% used interrupted sutures. The majority (64%) used 7–0 diameter sutures, 34% used 8–0 sutures, and 2% used other sizes.

When the question "Do you think you can achieve the same quality of anastomosis on a beating heart?" was posed, 62% responded no and 38% indicated yes. Seventy-four percent of responding surgeons stated they were either slightly or very uncomfortable with performing MICAB, with 26% stating that they were either comfortable or very comfortable. When asked what would most enable them to perform more complex MICAB procedures, 41% of surgeons indicated more personal experience was the most important factor, 38% believed improved coronary artery stabilization, 11% stated training courses, 8% thought ascertaining a bloodless field, and 2% stated improvement in video-assisted visualization.

Only 9% of surgeons routinely performed postoperative angiography, 20% used Doppler flow evaluation, and 7% used both. The majority (64%) used neither for the routine evaluation of anastomotic patency.

Eighty-one percent of surgeons considered the MICAB procedure to be an extension or modification of existing techniques, 15% considered it investigational, and only 4% considered it experimental (Fig 4).

View larger version (22K): [in this window] [in a new window]   Fig 4. . Survey question: "Do you consider minimally invasive coronary artery bypass grafting procedures:" Answers: (1) experimental; (2) investigational; (3) extension or modification of existing techniques.

	Prospective

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
When asked if they believe there is a role for MICAB, 63% stated occasionally, 20% responded rarely, and 17% thought the role was often. When asked the reasons why they were not performing more cases of myocardial revascularization without cardiopulmonary bypass, 30% stated the most limiting factor was the lack of patients with only one- or two-vessel disease, 12% stated they always aim to do complete revascularization limiting the number of cases suitable for MICAB, 4% believed the technique was more demanding, and 54% stated all of the above.

When surgeons were asked about their predictions of what percentage of coronary artery operations would be performed with current or future minimally invasive techniques in 5 years, the majority of respondents (57%) predicted that 11% to 25%, 31% predicted less than 10%, 12% predicted 26% to 50% of procedures, and none predicted this to exceed 50% of total coronary artery revascularization operations.

When asked what they thought would be the most important driving force for the expansion of MICAB, 38% of surgeons stated economic benefits of this procedure, 32% stated patient demand, 19% limited intermediate outcome of catheter intervention, and 11% stated that the most important driving force for the expansion of MICAB was cardiologist demand (Fig 5).

View larger version (22K): [in this window] [in a new window]   Fig 5. . Survey question: "What do you think will be the most important driving force for the expansion of minimally invasive coronary artery bypass grafting?" Answers: (1) patient demand; (2) cardiologist demand; (3) economic benefits of procedure; (4) limited intermediate outcome of catheter intervention.

When asked about limiting factors on future applicability of MICAB, 37% stated concern with risk of poor long-term outcome compared with conventional operations, 15% stated concern with potential early higher mortality and morbidity compared with conventional operations, 8% worried about possible poor long-term outcome compared with angioplasty and stenting, 5% stated risk of higher mortality and morbidity compared with angioplasty stenting, and 35% stated that none of the above would likely be a limiting factor for the future applicability of MICAB.

When challenged with a clinical problem: "What would be the procedure of choice for a 50-year-old man with 95% proximal LAD and 90% obtuse marginal lesion?", 73% stated they would perform conventional CABG, 21% stated MICAB to LAD plus percutaneous transluminal coronary angioplasty of obtuse marginal, and 6% stated percutaneous transluminal coronary angioplasty and stent of both lesions (Fig 6).

View larger version (20K): [in this window] [in a new window]   Fig 6. . Survey question: "My procedure of choice for a 50-year-old man with 95% proximal left anterior descending and 90% obtuse marginal lesions is:" Answers: (1) percutaneous transluminal coronary angioplasty + stent of both lesions; (2) conventional coronary artery bypass grafting; (3) minimally invasive coronary artery bypass grafting to left anterior descending + percutaneous transluminal coronary angioplasty of obtuse marginal.

View larger version (23K): [in this window] [in a new window]   Fig 7. . Survey question: "By the year 2000, most patients with three-vessel coronary artery disease will be managed by:" Answers: (1) medical therapy; (2) catheter intervention; (3) conventional coronary artery bypass grafting; (4) minimally invasive coronary artery bypass grafting; (5) combined "hybrid" catheter + minimally invasive coronary artery bypass grafting.

Finally, when asked their opinion on MICAB, 52% believed this was a potentially significant procedure but with isolated application, 21% recognized it as a significant watershed event in cardiac surgery, 26% refrained from giving an opinion as it is too early to state, and 1% believed it was much ado about nothing.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
In the past 2 years, there has been increasing interest in the application of less invasive access and technology to perform CABG [2, 7, 8, 12]. This survey examines the demographics of selected surgeons interested in MICAB, their choice of techniques, level of comfort, concerns, and overall views on MICAB. Currently, two schools of thought exist. One advocates performing CABG on the beating heart while eliminating the use of cardiopulmonary bypass unless required as bailout [3, 4, 9, 10]. The second advocates the use of cardiopulmonary bypass, aortic occlusion, and cardioplegic arrest through small access ports during the routine course of CABG [11–13]. There are theoretical advantages to both approaches. The first is a simpler technique that avoids additional cannulation, arterial manipulation, and side effects of administering cardiopulmonary bypass. It requires a level of expertise and in the absence of good stabilization of the coronary artery may result in less than adequate coronary artery anastomosis. The second approach uses standard principles of CABG (ie, cardiopulmonary bypass, aortic occlusion, and cardioplegic arrest). The need to use numerous thoracic access ports, cannulation of peripheral veins and arteries, intraaortic occlusion of the ascending aorta, administration of cardiopulmonary bypass, and mobilization of additional personnel to obtain intraoperative radiologic imaging adds to the cost of the operation and its duration. On the other hand, the security of conducting the operation in a milieu that is similar to that of conventional CABG with the heart arrested will likely permit the performance of a good anastomosis. Because none of these procedures have been studied prospectively or compared with conventional CABG, it is not possible to comment on their long-term safety and efficacy.

The interest of cardiac surgeons in less invasive CABG is evident by the increase in the number of articles published and abstracts presented at meetings. Registration of surgeons to educational symposia and conferences addressing minimally invasive CABG have been high with a great demand for more didactic and hands-on workshops.

It is clear from this survey that interest in minimally invasive CABG is highest in surgeons less than 55 years old. It is not surprising that most respondents have been involved in performing less than 10 cases with the main reasons for the slow adoption of the technique of CABG on the beating heart being the inability to stabilize the target coronary artery and concern with the quality of anastomosis. Despite this it was surprising to see that most surgeons adopted the view that MICAB was neither experimental nor investigational and that it was an extension or a modification of existing techniques. Furthermore, the majority of surgeons used neither Doppler flow nor angiography to assess the patency of their anastomoses.

It was interesting to know that short periods of cardiopulmonary bypass were not perceived as dangerous, yet the majority believed that avoiding cardiopulmonary bypass was the most important element in rendering CABG less invasive. Despite the reported low conversion to sternotomy and cardiopulmonary bypass, most surgeons required the presence of a perfusionist on standby. The majority of surgeons identified the need to have a larger clinical experience and improvement in their ability to stabilize the coronary artery as the most important factors that can improve their comfort level and the quality of the anastomosis [10]. These comments are not surprising at the infancy stage of MICAB and identify the need for industry to provide better instrumentation.

Despite the enthusiasm of cardiac surgeons to this new technology, expectations for current and future applicability appear to be realistic with the majority recognizing its current role as occasional and less than 25% of the total CABG pool in 5 years. Surgeons recognized that expansion of MICAB will be driven by its economic advantage and demand by patients. It was also interesting to identify that cardiac surgeons were open to the concept of "hybrid" revascularization in which both surgeons and interventional cardiologists would team to revascularize multivessel occlusions. It is clear from this survey that MICAB is rapidly gaining interest with more surgeons and centers seeking to learn it and adapt new technologies to improve on some of its current limitations. It is also clear that younger surgeons will likely be more enthusiastic and open minded to the applicability of MICAB procedures for single-vessel disease or a hybrid approach for selected multivessel disease. Until techniques are well established and standardized, and outcomes are verified, there is need for clear policy and recommendation on how to evaluate and practice MICAB.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 
Address reprint requests to Dr Shennib, The Montreal General Hospital, 1650 Cedar Ave, Suite L9–120, Montreal, PQ, H3G 1A4, Canada.

	References

Top Footnotes Abstract Introduction Material and Methods Results Technical Issues Prospective Comment References

 

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This Article Abstract 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): Hani Shennib Michael J. Mack Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shennib, H. Articles by Lee, A. G. L. Search for Related Content PubMed PubMed Citation Articles by Shennib, H. Articles by Lee, A. G. L.