Coronary Revascularization

Coronary artery surgery, which represents more than 90% of adult cardiac procedures nationally, offers some scope for a hybrid approach. The impact of graft failure after coronary artery bypass grafting (CABG) is well documented. In a recent prospective, multicenter study, the 1-year failure rate of saphenous vein grafts was reported to be more than 30%, that of the left internal mammary artery 8%, and the common end point of death or new myocardial infarction was 14% in these patients compared with 1% in patients with patent grafts.⁶ More recent data suggested saphenous vein failure rates of more than 40% at 12 to 18 months.⁷ Early graft failure, present in 5% to 20% of patients at discharge from the hospital, commonly is attributed to technical error and is the rationale for completion angiography with the option for percutaneous coronary intervention before leaving the operating room. In a recent series of 366 consecutive patients undergoing CABG surgery with completion angiography, 6% of all grafts required percutaneous coronary intervention to address technical problems compromising patency (including vein valves impeding flow [n = 9], left internal mammary artery dissection [n = 6], vein graft kinks [n = 7], and incorrect location or vessel [n = 8]). In an additional 49 cases (6.2% of grafts), angiography revealed problems that could be corrected either by minor adjustments such as removing a clip or adjustment of conduit lie or by traditional surgical revision⁸ (see Chapter 18).

The relatively high rate of early saphenous graft failure and the lack of clear prognostic benefit conferred by surgical revascularization of non–left anterior descending coronary artery territories has led some groups to explore the option of hybrid revascularization. In the earlier series, 60% (n = 67) of patients underwent planned percutaneous coronary intervention either immediately before or after CABG surgery. The majority of patients were selected for hybrid revascularization in an attempt to decrease the perceived risk for conventional surgical revascularization or because lesion anatomy favored stenting over surgery. There was one death in this group because of stent thrombosis in a patient who underwent left internal mammary artery grafting to the left anterior descending artery, and a hybrid stent to the left main stem coronary artery. There are no robust data on long-term outcomes in what are typically small, single-center studies.

The authors emphasized the importance of a collaborative working environment. Although they concluded that routine completion graft imaging should become the standard of care in coronary artery surgery, the authors identified several key considerations. Performing percutaneous revascularization immediately before chest closure, as opposed to 1 or 2 days after surgery, means that the patient is submitted to one, rather than two, procedures, and graft patency may be evaluated and addressed as described earlier. The disadvantages of this approach include the requirement for nephrotoxic contrast at the time of surgery, the additional procedural time and cost, the risk for acute stent thrombosis on reversing heparin with protamine, cardiac catheterization-related complications such as stroke or arterial injury, infection risk, and the need to give patients clopidogrel before surgery, with potential impact on bleeding complications.

Transcatheter Valve Replacement

An emerging modality that will likely become a mainstay of hybrid operating rooms is transcatheter valve replacements.⁹ Aortic valve replacement is the treatment of choice for symptomatic severe aortic stenosis; medical management is associated with high mortality, and balloon valvuloplasty offers temporary symptomatic relief without any associated survival benefit. Despite the low operative mortality of isolated primary aortic valve replacement, up to 40% of patients with American Heart Association/American College of Cardiology Class I indications for aortic valve replacement are denied surgery. Reasons most commonly cited by clinicians include advanced patient age and morbidity, and this is a driving force behind the development of transcatheter aortic valve implantation. Transcatheter aortic valve replacement has been performed via either the transfemoral or transapical approach in several thousand patients in Europe, and as of 2010, the U.S. Food and Drug Administration approved the procedure in the United States (see Chapter 19).

These techniques allow aortic valves to be replaced without CPB, large incisions, and in some cases, under sedation rather than general anesthesia. The device consists of a delivery catheter system (now as small as 18F in some devices), a disposable compression and loading system for the prosthesis, and the valve prosthesis. Several such prostheses are available and consist of pericardial valves mounted on compressible metal stents, which can be re-expanded once in position, allowing the valve to be delivered in a retrograde fashion without recourse to CPB, via a catheter placed in the femoral or axillary artery, or antegradely via the apex of the left ventricle, once the native aortic valve has been fractured and displaced by balloon inflation into the coronary sinuses. One key difference between the devices is how the valve is re-expanded once in position. The Cribier–Edwards valve (Edwards Labs, Irvine, CA) is expanded by inflating a balloon inside the valve once in position; cardiac output is zero for the few seconds required to expand the stent. In comparison, the CoreValve prosthesis (Core Valve, Inc., Irvine, CA) is mounted on a large, self-expanding nitinol stent, which allows left ventricular ejection to continue during stent expansion.

The device is guided into position with a combination of real-time transesophageal echocardiography (TEE) and fluoroscopy. Transcatheter valve replacement requires state-of-the-art imaging capability, as well as the ability to secure surgical access, potentially institute CPB, and convert emergently to general anesthesia and conventional aortic valve replacement. If the risk for conversion to open chest surgery declines as experience with the technique increases, the main obstacle preventing standard cardiac catheterization laboratories from being the optimal place to perform transcatheter valve replacement may become one of sterility because current building specifications between catheter laboratories and operating rooms in many countries differ in this regard.

The likelihood is that transfemoral aortic valve replacement will become the dominant treatment modality in high-risk patients requiring aortic valve replacement, greatly expanding the growing pool of eligible patients. Results have improved as both experience with the procedures and technology have developed, and currently mortality, associated stroke, major morbidity, and echocardiographic outcomes appear to offer very-high-risk and nonoperable patients a safe alternative to conventional surgery. Indications for transcatheter aortic valve implantation eventually may be expanded to lower-risk groups, based on outcomes of the large prospective clinical trials currently under way. Interventions for mitral and tricuspid valve repair are at a much earlier stage of development and are less likely to contribute significantly to the volume of hybrid procedures in the next decade.¹⁰

Hybrid Thoracic Aortic Surgery

Thoracoabdominal aortic disease increasingly is treated with hybrid procedures in which open repair, debranching, or bypasses are performed in conjunction with endovascular stenting. These procedures are particularly suited to hybrid suites capable of providing high-quality imaging, CPB capability, and optimal surgical conditions (see Chapter 21).

Hybrid Congenital Cardiac Surgery

Combined open and interventional approaches have been used successfully to treat multiple muscular ventricular septal defects, pulmonic stenosis, and hypoplastic left-heart syndrome. Hybrid techniques address the barriers to transcatheter approaches such as poor vascular access and hemodynamic compromise, as well as reduce the need for high-risk resternotomy and long CPB times (see Chapter 20).

Cardiac Electrophysiology

A hybrid suite would be the optimal location for totally endoscopic approaches to epicardial ablation combined with a modified transcatheter endocardial strategy, which may provide better long-term freedom from atrial fibrillation and stroke than patients treated using these methods in isolation, although data are currently limited to small, single-center series (see Chapter 4).