Minimally invasive mitral valve surgery: current status.

Cardiac surgery was the last area of surgery to become “minimally invasive,” and this began in the mid-1990s with some regularity at the Cleveland Clinic and the Brigham and Women's Hospital.1,2 Currently, there are several iterations of minimally invasive techniques for mitral valve surgery. The incisions first used at the Cleveland Clinic and the Brigham were a lower hemisternotomy or a right parasternal incision.3–5 More recently, the more frequently used approaches have been a right thoracotomy or a thoracoscopic right thoracotomy (either or both).6 Finally, the use of robotic mitral valve repair has become popular, albeit still controversial in terms of outcomes.7 The most important thing in minimally invasive surgery of any kind is that the new approach must yield results equal to or better than those of the approach that it replaces. At the Brigham and Women's Hospital, we have performed approximately 1,200 minimally invasive mitral valve repairs, including 1,000 through a lower mini-sternotomy, with cannulation of the right femoral vein for venous return and cannulation of the ascending aorta for arterial perfusion. We chose the lower mini-sternotomy because the mitral valve exposure is very similar to that of the full sternotomy and enables repair with the same degree of success as does the full sternotomy.8 At 10 years, the results of our miniseries were identical to those of the full-sternotomy series in our hospital and to those reported elsewhere.2,3 The right-thoracotomy approach has been thought to be more appealing for reasons of cosmesis and reduced trauma. This approach has been aided by the use of thoracoscopy and special instruments for long-distance knot-tying.6 Because the mitral valve is a posterior structure, excellent exposure can be established through either the lower mini-sternotomy or the right thoracotomy. A simplified right-thoracotomy approach includes peripheral cannulation with vacuum-assisted drainage in the heart-lung machine, a small right anterior lateral thoracotomy, and simple inexpensive handheld atrial retractors and long HeartPort instruments (Cardiovations Division of Ethicon, Inc., a Johnson & Johnson company; Redwood City, Calif). In the technique described here, no aortic cross-clamp is used—only cold fibrillatory arrest. Without an aortic clamp, myocardial protection is provided by hypothermia (28 °C), and a pacing swan (Edwards Swan-Ganz Pacing-TD Catheters; Edwards Lifesciences; Irvine, Calif) is inserted preoperatively to defibrillate.8 The technique does require an intact aortic valve, which enables perfusion of the coronary arteries and avoids ischemic injury to the heart or dilation of the heart from aortic regurgitation. In all minimally invasive valve surgery, the transesophageal echocardiogram is mandatory for quality control and intracardiac air evacuation, so our partnership with our cardiac anesthesiologists has become intrinsic to the success of these techniques. Careful de-airing is performed while closing the left atrium. Carbon dioxide infusion into the operative field can help decrease the chance of air embolism. If a mitral valve replacement is performed for ischemic mitral regurgitation, chordal sparing is, of course, essential. In the Vanderbilt right-thoracotomy series,8 the 30-day mortality rate for patients with ischemic mitral regurgitation who had a Society of Thoracic Surgeons index greater than 10% was 4.3%. In patients with a prior sternotomy, most of whom had undergone coronary artery bypass grafting, the operative mortality rate was only 3.1% when the right-thoracotomy approach was used.8 Minimally invasive mitral valve surgery through a right thoracotomy without aortic cross-clamping is simple, reproducible, and easily learned. The final iteration of minimally invasive mitral valve surgery is robotic mitral valve repair via right thoracotomy and several incisions for port access. Initially, this was thought to be much less traumatic, but an important factor emerged in the early reporting of results. Substantial experience of the operator in conventional mitral valve operations (at least 100 prior cases) is essential to achieve equal or better results with the robotic approach.9 Although supported in many papers from series in Greenville, North Carolina,7 the Mayo Clinic,9 and the Cleveland Clinic,10 robotic operations tend to be longer and the technology more expensive. Yet patient satisfaction after a successful robotic mitral valve repair is very high because of exceptionally small incisions and minimal trauma. The references listed below represent all techniques and approaches to minimally invasive mitral valve surgery, again emphasizing that an experienced mitral valve surgical team will achieve excellent results with minimally invasive reparative surgery performed by a variety of techniques. Understanding of mitral valve pathophysiology and sufficient prior experience in mitral valve repair surgery are the keys to success in minimally invasive approaches.