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Minimally Invasive Bypass Surgery

The four-part Nova series, "Surgery, the Brutal Craft," which first aired on PBS in 1988, traces 150 years of history in the development of modern surgery. Starting with amputations without analgesia or antisepsis, the program takes the viewer up to the contemporary (at the time) triumphs of cardiac surgery and transplantation. Based largely on interviews with pioneers like Drs. Norman Shumway and Adrian Kantrowitz, the underlying theme slowly unfolds: the advancement of modern surgical practice will ultimately lead to the elimination of surgery as we know it -- to the demise of the so-called brutal craft.

Although the revolution in surgery did not start till the end of the 1990s, the development of minimally invasive techniques has radically changed the surgical landscape.

In modern cardiac surgical repertoire, virtually every operation can be performed by splitting the breastbone (midline sternotomy), placing the patient on the heart-lung machine, and temporarily stopping the heart. Coronary arteries can be bypassed, heart valves can be repaired or replaced, aneurysms (out pouching of the aorta or the heart chamber) resected, and congenital (birth) defects fixed.

While this basic cardiac operation is highly effective, it is also highly invasive. The breastbone sometimes does not heal properly. Emboli (particles of blood clot or tissue) can travel to any organ causing stroke, heart attack, kidney or liver failure. Inflammatory mechanisms in the body are stimulated and the ability to fight infection reduced. The heart can be weakened during the period when it is stopped.

Toward Minimally Invasive Surgery

There are three basic approaches to making cardiac surgery less invasive. First a partial cut of the breastbone (partial sternotomy) or a cut between the ribs (thoracotomy) can be substituted for full division. This usually results in a smaller incision, less pain, less breathing difficulties, and less risk of infection. Second, almost all coronary bypass surgery and a few other procedures do not require stopping the heartbeat and, therefore, do not require use of the heart-lung machine. This should reduce the risk of emboli, inflammatory, and immune reactions.

Such surgery is called "off-pump" or "beating heart" surgery, and when used for coronary bypass, "OPCAB" (off-pump coronary artery bypass).

Lastly, one can approach some problems by traversing the body's arterial system (access is through a groin with a needle) to deliver a device, most commonly some form of stent. The "endovascular" (within the vessel) approach can be used to treat many forms of aneurysm, and to deliver aortic valve replacement devices. The most common form of endovascular procedure is the coronary stent, which cardiologists perform in great number.

As a general rule for cardiac procedures, less invasive techniques lead to less effectiveness in general, and great care should be exercised in selecting patients who will truly benefit. Just because a minimally invasive procedure exists does not mean that it is the best, nor that it is the right choice.

Take, for instance, the phenomenal rise in percutaneous coronary interventions (PCIs) for coronary artery disease (CAD), also known as angioplasty and stenting.

The number of PCIs performed per year in this country is nearly four times the number of coronary artery bypass grafting (CABG) surgeries performed. Numerous studies both old and quite new have tried to prove that PCI and CABG are equally effective in the more severe forms of CAD, and essentially all of these studies have failed. In terms of the treatment of CAD overall, the vast majority of studies have shown that the long term survival and risk of heart attack are similar for PCI and CABG, but patients are significantly less likely to need additional procedures (i.e., more stents or actual bypass operations) with CABG versus PCI.

Minimally Invasive Bypass

Minimally invasive coronary artery bypass surgery was rediscovered in the mid-1990s. It was rediscovered, because the first CABG procedures were actually done off-pump; these early off-pump procedures persisted in small numbers in institutional settings where the cost of using heart-lung bypass techniques was prohibitive.

In response to the growing application of coronary stenting by cardiologists, many cardiac surgeons refined these early techniques and, in cooperation with industry, developed stabilizing and exposure instruments that now, in experienced hands, allow for the performance of multi-vessel bypass in over 95% of patients with CAD.

OPCAB, as it has become known, a beating heart coronary bypass technique performed through a full sternotomy, frees the patient from the potential medical problems associated with the heart-lung machine and with manipulation of the aorta. It is technically more difficult, both for the surgeon and the anesthesiologist, and significant experience is required on the part of the team to achieve good results.

Although small, usually single-surgeon, studies have shown significant outcome improvement over traditional on-pump CABG, larger studies with less experienced surgeons have had more equivocal results. Most agree that OPCAB is a better choice for high-risk patients, those with cerebrovascular disease (stroke), kidney failure, and calcified ascending aorta, and for women.

At Stony Brook University Hospital, during the last 15 years, nearly half the CABG procedures performed were done using the OPCAB method; the number of OPCABs done to date far exceeds 2,500 cases. Between 2003 and 2007, Stony Brook University Hospital was a designated center for the teaching of OPCAB techniques. From 2003 and 2007, Stony Brook University Hospital was a designated center for the teaching of OPCAB techniques.

When beating heart techniques are applied as a single vessel bypass through a small thoracotomy (a cut between the ribs), we call the procedure a MIDCAB (minimally invasive direct coronary artery bypass). Focusing on the delivery of a left internal mammary artery (LIMA) bypass to the left anterior descending coronary artery (LAD; the "most important" artery in the heart), MIDCAB operations were developed in parallel with OPCAB.

The MIDCAB Approach

MIDCAB allows treatment of single-vessel CAD in situations where a stent cannot be deployed, or it is used in preference to a stent because the LIMA-LAD bypass that results is considered the "gold standard" of coronary revascularization.

The incision used to perform MIDCAB is much smaller than that used for the sternotomy of the conventional CABG operation. Not only that, it is made between two ribs, and involves no cutting of the breastbone. Thus, in these two ways (and for other reasons, incl. absence of heart-lung machine), it is considered minimally invasive.

As a consequence of the reduced invasiveness of the MIDCAB operation, the procedure usually cannot be used for more than one bypass. If the MIDCAB procedure is combined with stenting procedures to other diseased vessels, this hybrid procedure offers, in many cardiologists' opinions, the "best, least invasive, complete revascularization" to the patient with multi-vessel CAD.

MIDCAB operations are less common than OPCAB operations, and are even more demanding of the surgeon's skill and experience.

At Stony Brook University Hospital, we have performed nearly 500 MIDCABs in the last 15 years. Many of the MIDCAB operations were part of a planned hybrid procedure, with stenting of the other diseased vessels. And many of the MIDCAB operations were highly customized to meet the unique needs of individual patients. In the last 100 MIDCAB procedures, the surgical robot was used to enhance the operation.

Robotically-assisted MIDCAB operations substitute the use of the surgical robot for direct mammary artery takedown by the surgeon. The surgical robot has no autonomy; it is an indirect extension of the surgeon's hands and vision with significant enhancement of both.

The technical advantages of the robot result in a longer, more versatile LIMA graft, and the possibility of utilizing the right internal mammary artery (RIMA) for multivessel bypass. Not only that, the robot requires only three small port holes to harvest the vascular grafts, greatly reducing the thoracotomy size required for the direct vascular anastomosis (joining the LIMA to the LAD).

In a sense, robotically-assisted MIDCAB is an exception to the rule that reducing invasiveness leads to reduced effectiveness.

With the continued revolution in surgery that has transformed the once "brutal craft," it is unlikely that traditional MIDCAB procedures will persist in any institution with access to the surgical robot. Between 2008 and 2014, we performed over 100 robotically-assisted MIDCABs at Stony Brook University Hospital, one third of which were part of a planned hybrid intervention. And we continue to increase our experience with this minimally invasive, 21st-century robotic approach to heart surgery, as more and more patients benefit from it.