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Ann Thorac Surg 1996;61:1786-1787
© 1996 The Society of Thoracic Surgeons
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305
Small incisions and a variety of instruments and videoscopes designed to allow minimally invasive operations are currently revolutionizing many surgical disciplines. Although the technical challenges are great when considering cardiac operations, Dr Pyng Jing Lin and colleagues from the Chang Gung Memorial Hospital in Taipei, Taiwan, are to be congratulated for their early efforts. In their report, 2 patients with mitral valve disease were treated by a small anterior thoracotomy incision with assisted visualization using a video thoracoscope. The clotted mitral prosthesis in 1 patient was debrided, and the mitral regurgitation created when a chordal rupture occurred was effectively repaired. Lin and associates clearly point out that their operative times, cardiopulmonary bypass times, and lengths of stay in both the intensive care unit and in the hospital are not different from standard mitral valve operations. In fact, the intraoperative times are probably considerably prolonged. However, the early results in these 2 patients are promising and suggest that, even with these deficiencies, the patients made nice recoveries and were doing well at follow-up.
Approaching the heart through smaller and smaller incisions provides many challenges for the surgeon. A concerted effort requires addressing each of them. The first of these is to obtain optimum visualization at all times. Current video technology, as used in the patients at Chang Gung, seems to be satisfactory for most applications. Direct vision may also be feasible, as in minithoracotomy for left internal mammary bypass to the left anterior descending artery. However, further efforts at creating a three-dimensional video image will be particularly helpful for cardiac surgeons operating on the heart.
The second challenge is the ability to perform all of the necessary technical maneuvers. Because the access is through limited incisions, many of the currently available instruments will need to be modified for these new approaches. Shafted forceps, needle holders, retractors, and others may need to be developed. Some may be available from currently developed laparoscopic instruments, but certainly the surgeon will require additional tools specifically constructed for heart surgery.
The third challenge will be to provide adequate myocardial protection that is at least the equivalent of that currently achieved with conventional open surgery. This report uses fibrillation with the aorta unclamped; however, this technique would seldom be used for mitral valve surgery with current open operations. Thus, a method to provide standard cardioplegic arrest and a bloodless operative field would be preferred, or indeed be mandatory. Lin and associates' first patient had aortic regurgitation, and anyone who has operated on the fibrillating heart in the presence of aortic regurgitation knows the tremendous technical disadvantage that this creates. An alternative approach using an endovascular balloon aortic clamp on a catheter-based system is currently being tested at Stanford. Both coronary artery bypass and mitral valve replacement are facilitated by its use, as demonstrated by experimental studies in our laboratory, as well as a clinical study of single-vessel coronary artery bypass. Further clinical application of the endovascular balloon clamp will soon be forthcoming. This seems to us to be the current best method for producing cardioplegic arrest of the heart, although undoubtedly other technologies will be developed.
A further technical challenge that needs to be dealt with is the ability to assess the heart and treat both expected and unexpected findings or complications encountered during the course of the operation. It should be clear that surgeons should not compromise the quality of the operative repair because of the efforts at using small incisions. If some element of the procedure is considered essential for obtaining an excellent result, it should not be eliminated or altered in the course of the minimally invasive approach; for example, moving toward mitral valve replacement rather than repair because of a technical limitation of the minimally invasive approach.
Morbidity associated with the new approach should not be substantially greater than that of standard operations, so that the anticipated benefits of minimally invasive approaches are achieved. In this regard, Lin and associates mentioned the absence of neurologic complications, but pointed out the difficulties with adequate deairing of the heart from the minimally invasive approach. This will be the subject of many investigations, and talented surgeons will undoubtedly develop methods for overcoming this potential problem. In addition, the morbidity associated with femoral artery and vein cannulation with respect to perfusion, as well as thrombosis of the femoral vein and possible pulmonary embolism, must be within acceptable limits to justify the new approach.
It is yet to be determined whether the economic and patient comfort benefits that usually accompany minimally invasive approaches are in fact realized. Early data from several centers performing minimally invasive coronary artery bypass using the left internal mammary artery to the left anterior descending artery, both with a beating heart and with the arrested heart, support the concept that patients recover quickly and are able to return to work in a much shorter time than with conventional median sternotomy. More data are required, however, before firm conclusions can be made. Undoubtedly, reports will now come in rapid succession, testing new technologies and techniques for performing minimally invasive cardiac operations. Already very technically oriented and innovative, cardiac surgeons will continue to refine the methods they use to benefit their patients in much the same way that Dr Pyng Jing Lin and colleagues have done.
Related Article
Ann. Thorac. Surg. 1996 61: 1781-1786.
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