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Ann Thorac Surg 1998;66:1101-1105
© 1998 The Society of Thoracic Surgeons
a Texas Heart Institute, Houston, Texas, USA
Address reprint requests to Dr Cooley, Texas Heart Institute, PO Box 20345, Houston, TX 77225-0345
e-mail: (dcooley{at}biost1.thi.tmc.edu)
Presented at "Facts and Myths of Minimally Invasive Cardiac Surgery: Current Trends in Thoracic Surgery IV," New Orleans, LA, Jan 24, 1998.
Abstract
As a result of reports touting the effectiveness of minimally invasive valve operations, many cardiovascular surgeons and their patients are beginning to believe that smaller incisions are always better. According to its proponents, the minimally invasive approach results in less pain, a faster recovery, and a more satisfactory cosmetic result. Proponents also believe that the operation can be done safely and effectively at a lower cost than traditional surgical approaches. This may not be the case, however, and additional prospective studies must be done before firm conclusions can be drawn. For example, cardiopulmonary bypass, myocardial ischemia, and overall operative times are significantly longer (40% or more) for minimally invasive surgical procedures. Morbidity and mortality rates do not appear to be decreased, the length of hospital stay varies by only 1 or 2 days, and patients do not necessarily report less postoperative pain. When the conventional technique is used, the operation can be performed precisely and expeditiously. Should complications occur, the surgeon will have direct access to the heart. The cost of a conventional procedure should not be much more than that of a minimally invasive procedure, and in some instances it may even be less—particularly when the less invasive procedure significantly extends the operating room time or requires additional monitors or costly disposables.
"It is not the critic who counts ... or the man who points out how ... the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena. ... " Theodore Roosevelt
These oft-quoted, powerful lines apply to many of life’s arenas, including that of medical researchers and clinicians who pursue new methods and techniques, ostensibly for the betterment of humankind. Throughout my career, I have been involved in the surgical arena, developing operative techniques such as cardiopulmonary perfusion with crystalloid cardioplegia for priming the extracorporeal circuit [1], hypothermic circulatory arrest [2], cardiac transplantation [3], implantation of a total artificial heart [4], use of exsanguination in the treatment of aortic aneurysms [5], and others.
Minimally invasive techniques, which have recently been added to the surgical arena, have captured the interest and imagination of cardiac surgeons throughout the world. Nevertheless, some concerns remain. For example, public opinion increasingly holds that less invasive, smaller incisions are always more desirable, but this may not be true. Another concern involves the marketing of minimally invasive techniques that require sophisticated equipment to implement. Although the equipment was designed to satisfy requests from a few surgeons, product manufacturers cannot recoup their costs without marketing to all cardiac surgeons, regardless of expense of the technique and possible risk to the patient. Thus, the following cautionary message is intended not to be reactionary or antiprogressive but, rather, to encourage discretion and sound judgment on the part of the surgical profession. Providing the best and safest care for our patients must always remain our goal.
Background
The past decade has seen a growing emphasis on less invasive surgical procedures. Incisions have become increasingly smaller as endoscopic techniques have been developed. In the past few years, minimally invasive techniques for cardiac operations have been growing in popularity. In particular, single-vessel coronary artery bypass grafting seems well suited to this approach. Most recently, valvular operations have been added to the list of procedures amenable to the minimally invasive technique. In February 1996, Carpentier and coworkers [6] successfully performed the first video-assisted mitral valve repair through a minithoracotomy incision. Three months later, Chitwood and colleagues [7] performed a direct-vision micromitral repair, also through a minithoracotomy. Others soon followed with additional mitral repairs, and Cosgrove and Sabik [8] reported their experience in performing aortic valve procedures through a right-sided parasternal incision.
In comparing minimally invasive valvular operations with the conventional approach, proponents of the new procedure all state that the smaller incisions are more "patient friendly." Patients have less pain, a faster and smoother recovery, and a more satisfactory cosmetic result. According to proponents, the operation is also just as "friendly" for the surgeons. It can be done safely with or without video-access techniques, and when necessary, peripheral cannulation can be accomplished without incident. Moreover, enthusiasts claim that all of these benefits entail much lower cost. Nevertheless, a reality check shows that each of these benefits has limitations.
Patient-friendly aspects
Less pain
Many types of incisions have been used for minimally invasive valvular operations, including the parasternal incision, the ministernotomy, the transverse sternotomy, and the intercostal incision. The parasternal incision usually requires peripheral cannulation; the extra incision increases pain. In addition, the left atrial roof, interatrial septum, and even the sinoatrial nodal artery may need to be divided to expose the valve; this maneuver may result in early postoperative arrhythmias.
Some proponents of minimally invasive surgical procedures advocate small intercostal incisions. In my experience, however, patients have had pain longer after an intercostal incision than after a midline incision. In addition, removal of the costal cartilages can cause herniation of the lung or a chest wall defect. Postoperative pneumonia is also more common in patients who have had intercostal incisions. None of these complications is without pain.
When a ministernotomy is used, the surgeon may have trouble determining how far caudad to extend the incision, because of the varying height of the aorta. However, this approach does allow for cannulation of the right atrium and the distal ascending aorta, and it usually provides good exposure of the mitral valve. The exposure is not as good if the atrium is small, however, and pain is not significantly lessened by the shorter incision.
The transverse sternal incision at the level of the third intercostal space has also been used in minimally invasive valve repairs. When the sternum is transected, however, both internal thoracic arteries may be lost and unavailable for future or concomitant coronary artery bypass grafting. Although some surgeons believe that subsequent bypass operations are unlikely [9], I do not think that we should ever eliminate a possible bypass conduit. If a calcified valve is seated deeply in the chest and the plane of the valve is inclined, operations through a transverse sternal incision may be difficult technically without video assistance [10].
After a valvular repair through any of these incisions, evacuation of air from the heart becomes more difficult, making embolism an ever-present threat. In a standard open heart operation, the surgeon can lift the apex of the left ventricle to aspirate contained air. Because this is not possible in a minimally invasive procedure, the aorta becomes the only site for air evacuation. Proponents believe that air can be visualized on transesophageal echocardiography (TEE), but the use of TEE adds significantly to the operative time, and TEE may not always be accurate. The possibility of entrapping air in the left atrium and ventricle remains. In at least two series, an electrocardiogram obtained immediately after cardiac arrest showed inferior-lead changes, despite evacuation and monitoring with TEE [11, 12]. The changes in these patients resolved, however, without causing ventricular dysfunction.
In some patients, coronary artery bypass grafting may be required on an emergent basis. Unless a conventional sternotomy incision is used, the surgeon will not have complete access to the internal mammary and coronary arteries. Other patients will need concomitant coronary artery bypass grafting. In our hospital, 22,319 patients have undergone valve operations since we began our database in 1975. Of these patients, 4,271 (19%) required a concomitant coronary artery bypass graft procedure—most needed three or more bypass grafts. Seldom could concomitant coronary artery bypass grafting be performed easily during a minimally invasive operation for valve repair or replacement.
Faster, smoother recovery
Patients may recover faster from parasternal or intercostal incisions than from sternotomy incisions. However, the length of a sternotomy incision is not a factor in recovery. The sternotomy incision that we use in performing a conventional repair (Figs 1, 2) is not much more invasive than a ministernotomy incision and provides much better exposure. Retraction is done in a pyramidal rather than a rectangular shape and is limited to a necessary minimum. Wide retraction is always avoided. Keeping the width of the cephalad portion narrow may prevent brachial plexus injury, one of the complications associated with the conventional sternotomy. Patients also have less pain and recover more quickly with the pyramidal approach because the sternum is not overstretched. The average length of stay for patients who undergo valvular repair through a sternotomy in our institution is 6 to 7 days. For minimally invasive procedures, the reported length of stay has usually been 5 or 6 days [11, 13]. The extra days in the hospital may be necessary to adjust anticoagulant medications.
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Lower cost
Are costs really lower with minimally invasive surgical procedures? One study showed that costs and hospital charges decreased by 34% and 27%, respectively; however, the increased operating room time was considered part of the cost of the procedure and was not included in the total [11].
Equipping a center to perform minimally invasive cardiac operations is also expensive. Capital equipment costs may include an endoscopic video-assistance system, TEE, and a C-arm fluoroscope, which is needed for placing the cannulas and equipment. The extra disposables for Port-Access (Heartport, Inc, Redwood, CA) procedures alone cost $5,000. The extended time needed to insert the extra equipment in patients under general anesthesia yields additional operating room and personnel charges. In our hospital, operating room time costs approximately $1,500 for 30 minutes, and these operations take at least an hour and a half longer than conventional procedures.
Surgeon-friendly aspects
I do not believe that minimally invasive cardiac procedures are necessarily "surgeon friendly" or that every cardiovascular surgeon should be performing them. Only after gaining significant experience in conventional valvular operations through a standard sternotomy should a surgeon attempt such stunts.
The minimally invasive valvular operation requires significantly more time than conventional surgical valve repairs. Even experienced surgeons report cardiopulmonary bypass times of 114 ± 26, 151 ± 52, and 183 ± 7.2 minutes [11, 14, 15]. Others have reported even longer bypass times [16]. In these same series, aortic cross-clamp times averaged 76 ± 19, 99 ± 22, and 136 ± 5.5 minutes [11, 14, 15]. Total operating times averaged 190 ± 40 minutes and 260 minutes [14, 15]. In one report, the mean cardiopulmonary bypass time was 222 minutes, and a patient who underwent mitral valve thrombectomy required 320 minutes of cardiopulmonary bypass [17]. In this same report, the mean operating time was 6.1 hours. None of the different incision types seem to offer a faster operating time. Rather, more time is required for the technical aspects of the procedure and for evacuating air before release of the cross-clamp or removal of the occluding balloon.
As in all procedures, there will be complications, necessitating that the surgeon access the heart quickly. The threat of complications, which are often unexpected, can add to the insecurity of surgeons who perform minimally invasive procedures. For example, a recent case report described a patient in whom unexpected hypotension developed as a result of mechanical compression of the right ventricle after cardiopulmonary bypass [18]. Although the problem was corrected after it was shown by TEE, it would have been identified easily and quickly under direct vision. In addition, with minimally invasive access, the heart cannot be raised for massage or defibrillated directly.
Placement of the balloon aortic occluder is also subject to potential complications. Positioning the balloon catheter at the proper level in the ascending aorta can be difficult. However, optimal anatomic positioning and maintenance of the balloon are essential to keep the device from becoming dislodged during manipulation. If the balloon does become dislodged, innominate artery occlusion with resultant neurologic complications can ensue. Balloon misplacement may also cause aortic valve incompetence, left ventricular distension, unequal distribution of cardioplegia, or compromised perfusion of the arch vessels [15]. Transesophageal echocardiography or fluoroscopy is essential for placing the balloon.
The technical aspects of the minimally invasive procedure are also more difficult. For example, tying knots, especially anterior annular sutures, can be tedious. To facilitate the procedure, special efficient suture holders and instruments are needed. In addition, three-dimensional video could restore some of the visual perspective lost in such a deep operative field.
Although this new valvular procedure is labeled "minimally invasive," the need for blood products—normally a sign of a more invasive procedure—has not decreased. Blood-product transfusions have been as high as 38%, most likely because of longer perfusion times and attendant increased hemodilution [11].
Cannulation
For conventional valvular operations, the right atrium or vena cava and the ascending aorta are cannulated. In many techniques, transfemoral cannulas are needed, requiring an additional groin incision. Groin incisions are subject to more complications, including pain, infection, and lymph drainage. The venous site is prone to late thrombosis, pulmonary embolism, and thrombophlebitis. Cannulation of the arterial site, especially in patients with arteriosclerosis, may be hazardous or technically impossible. There is always a possibility of retrograde dissection, ischemic complications, and delayed wound healing. An undetected abdominal aneurysm could add further complications. Recently Bichell and colleagues [19] proposed axilloaxillary cannulation as a possible solution. With this technique, they achieved flows of 3 L/min. Two of their 7 patients, however, incurred a transient brachial plexus neuropathy that resolved before hospital discharge. Brachial plexus injury remains a potential complication after use of this cannulation site.
Comment
Although minimally invasive procedures may have psychological benefits for patients, I believe that we must continue to scrutinize the results to determine whether these procedures are really "minimally invasive." We must also remember that minimally invasive operations entail a distinct learning curve—because of the deeper operative field and attendant technical difficulties, as well as the use of new equipment and methods.
Early data regarding valvular procedures seem positive but describe small series of patients with short follow-up times. Thus, more data are needed before firm conclusions can be made. Most authors admit that the procedures are reserved for the least complex cases, and morbidity and mortality rates do not appear to be much lower than those of conventional valvular operations. In conventional valve repair, the mortality of lower-risk patients is about 1%; in some minimally invasive series, the mortality rates were 2% [13] to 5% [20].
In addition, the significantly longer cardiopulmonary bypass times are a problem with minimally invasive valvular procedures. As Lytle has asked, "Is a smaller incision worth a longer pump run?" [21]. Cohn and colleagues [20] published an interesting report that compared two groups of 50 patients each who had undergone minimally invasive or conventional procedures. In their patients, cardiopulmonary bypass time increased by almost 40%. In many other reported series, the percentage would probably be higher, as the cardiopulmonary bypass times were longer [11, 15–17] than those reported by Cohn and associates. Of the 84 patients in the overall series studied by Cohn and coworkers who underwent minimally invasive aortic or mitral valve operations, 16 had atrial fibrillation postoperatively (19%), 7 had groin complications (8%), 1 had an intraoperative dissection, 2 had episodes of bleeding (involving the aortic valve), and 41 required transfusions (49%). In comparing minimally invasive and conventional repairs, no significant difference was noted in the amount of pain felt either during hospitalization or after 2 weeks. In fact, on a scale from 0 to 10, pain during hospitalization was ranked by patients as 4.1 for minimally invasive procedures and 4.4 for conventional operations. After 2 weeks, the patients rated pain at 1.7 for minimally invasive operations and 2.4 for conventional approaches. Although there was not a significant difference in the time missed from work, patients in the comparison subset returned to normal activities and felt "like themselves" significantly faster (4.6 versus 9.4 weeks and 6.4 versus 10.3 weeks, respectively). Overall charges were 20% less for the minimally invasive group, but it was not clear whether "charges" included hospital charges and costs, and whether operating room time and capital expenditures were included. There was only 1 day’s difference between the two approaches with respect to length of hospital stay (5 days for minimally invasive valve operations versus 6 days for the conventional approach).
Under any circumstances, surgeons should refuse to compromise the clinical outcome of an operation just to satisfy a desire to be innovative or to improve their image among their peers or the public. The choice of operative technique must fit the patient. Whenever possible, surgeons should choose the simple approach and avoid unproven innovations. Let it not be on any surgeon’s conscience that a failed effort to be an innovator harmed a patient.
Footnotes
1 This article was produced as part of a debate on "Minimally Invasive Versus Conventional Valve Surgery." Doctor Cooley addressed the conventional side.
The Editors 
References
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  I. Bakir, F. P. Casselman, F. Wellens, H. Jeanmart, R. De Geest, I. Degrieck, F. Van Praet, Y. Vermeulen, and H. Vanermen Minimally invasive versus standard approach aortic valve replacement: a study in 506 patients. Ann. Thorac. Surg., May 1, 2006; 81(5): 1599 - 1604. [Abstract] [Full Text] [PDF]
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 H.-S. Sun, W.-G. Ma, J.-P. Xu, L.-Z. Sun, F. Lu, and X.-D. Zhu Minimal Access Heart Surgery via Lower Ministernotomy: Experience in 460 Cases Asian Cardiovasc Thorac Ann, April 1, 2006; 14(2): 109 - 113. [Abstract] [Full Text] [PDF]
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W. Luo, C. Chang, and S. Chen Ministernotomy versus full sternotomy in congenital heart defects: a prospective randomized study Ann. Thorac. Surg., February 1, 2001; 71(2): 473 - 475. [Abstract] [Full Text] [PDF]
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F. Schneider, J.-F. Onnasch, V. Falk, T. Walther, R. Autschbach, and F. W. Mohr Cerebral microemboli during minimally invasive and conventional mitral valve operations Ann. Thorac. Surg., September 1, 2000; 70(3): 1094 - 1097. [Abstract] [Full Text] [PDF]
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M. F. Szwerc, D. H. Benckart, R. J. Wiechmann, E. B. Savage, G. W. Szydlowski, G. J. Magovern Jr, and J. A. Magovern Partial versus full sternotomy for aortic valve replacement Ann. Thorac. Surg., December 1, 1999; 68(6): 2209 - 2213. [Abstract] [Full Text] [PDF]
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L. K. von Segesser, S. Westaby, J. Pomar, D. Loisance, P. Groscurth, and M. Turina Less invasive aortic valve surgery: rationale and technique Eur. J. Cardiothorac. Surg., June 1, 1999; 15(6): 781 - 785. [Abstract] [Full Text] [PDF]
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A. Aris, M. L. Camara, J. Montiel, L. J. Delgado, J. Galan, and H. Litvan Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study Ann. Thorac. Surg., June 1, 1999; 67(6): 1583 - 1587. [Abstract] [Full Text] [PDF]
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F.W. Mohr, J.F. Onnasch, V. Falk, T. Walther, A. Diegeler, R. Krakor, F. Schneider, and R. Autschbach The evolution of minimally invasive mitral valve surgery - 2 year experience Eur. J. Cardiothorac. Surg., March 1, 1999; 15(3): 233 - 239. [Abstract] [Full Text] [PDF]
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