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).

Lights, Monitors

Surgical lights and banks of four to six imaging monitors (or, preferably, large flat-panel screens that can support multiple video inputs) are housed on overhead gantries. Optimally, monitors that display continuous invasive and noninvasive monitoring of vital signs should be placed in four quadrants of the room, in addition to the imaging monitors, which should be located opposite the surgeon, as well as in the control room. A specific plan should be created, including all ceiling-mounted components (lights, monitors, booms, air-conditioning, C-arms, etc.) to minimize collisions between devices (Figure 26-1). Conventional surgical lights are often mounted on very long gantries. It can be difficult to position the lights adequately and maintain sterility without assistance, without interfering with sight lines or other equipment, particularly the overhead monitors. A video camera integrated in the main overhead light enables nonsurgical personnel to obtain a view of the surgical field.

Figure 26-1 Floor plan showing the layout of a hybrid cardiovascular suite, including the working arcs of three booms, C-arm, operating lights, and monitoring gantries; location for bypass circuit; and ancillary rooms.

(Courtesy of Alfred I. Dupont Hospital for Children.)

Infection Control

The two main focuses of infection control are preventing contamination of the hybrid site and adjacent operating rooms during construction and maintaining hygiene once the room is in use. It frequently is necessary to change or limit access to existing facilities and utilities during building work, and eliminating low-level contamination of nearby rooms is challenging. Rigorous infection control risk assessments are mandatory before and during construction. Requirements for infection control once construction is completed differ between surgical disciplines and between countries. Standard provision by many centers now includes laminar air flow with specified volume changes. Ceiling skirts, which are often used in conjunction with laminar flow systems, preclude ceiling-mounted imaging gantries. Furthermore, ceiling-mounted systems are more difficult to clean than floor-mounted systems, interfere with air flow, and may increase the risk for dust contaminating the surgical field if running parts cross the ceiling above the operating table. Their main advantage is that they can move up and down the entire operating field without putting tension onto lines and catheters. Touch panel–operated doors and daily terminal cleaning contribute to optimal infection control once the hybrid room is running.

Both a surgical suite, in which the operating room is located, and a cardiac catheterization suite are required to have staff locker facilities that encourage one-way changing from street clothes to scrubs. A catheterization suite should maintain the same semirestricted and restricted areas that are required in a surgical suite. In terms of dress codes, the standard two-step policy for surgical attire is applied to the hybrid operating room. Education of nonsurgical personnel, who are less familiar with the strict antisepsis requirements required in a cardiac operating room, is mandatory.

Imaging Equipment

Fluoroscopy is the basic imaging mode provided by all angiography systems, and is the predominantly used modality during surgery because it exposes the patient to less radiation and provides high-resolution, real-time images. Biplanar rather than monoplanar imaging is essential for interventional cardiology-based procedures. Two kinds of C-arms are available: mobile and fixed. Mobile C-arms, which surgeons currently use routinely for screening for missing instruments and catheter placement, are not adequate for visualizing thin guidewires or fine stents or quantifying stenosis of small vessels. The technical specifications for power, frame rate, and heat storage capacity of mobile C-arms are well below those set by the regulatory bodies, and for a room to work as a true hybrid cardiovascular suite, a fixed C-arm should be installed (Figure 26-2). Where available space is lacking, a semimobile system with a fixed generator may be a reasonable compromise. Flat-panel detectors are preferable to image intensifiers because contrast resolution is higher; there is no edge distortion effect, and flat-panel detectors offer three-dimensional (3D) imaging capabilities (see Chapter 3).

Figure 26-2 View of a hybrid cardiovascular operating room.

The cardiopulmonary bypass circuit is on the far right with its own boom. The operating table is in the middle of the picture, with a floor-mounted, fixed biplanar C-arm to the left.

(Courtesy of Alfred I. Dupont Hospital for Children.)

Postprocessing of fluoroscopic images allows 3D images to be generated, as well as fusion of fluoroscopic images with any previously acquired 3D images including computerized tomography, magnetic resonance imaging, positron emission tomography, and single-photon emission tomography. The C-arm must be integrated with the operating table if 3D imaging is planned. Fixed C-arms may be ceiling or floor mounted. Although floor-mounted systems are preferred for hygiene reasons outlined earlier, ceiling-mounted systems can image the whole patient without the need to move the operating table, associated lines, catheters, and monitoring and easily can be moved in and out of the operative field as required. Careful attention needs to be paid to idle and working positions. It often is difficult to mobilize a ceiling-mounted C-arm left at the head of the patient during a procedure without interfering with anesthesia and monitoring equipment. Designing a hybrid suite where large imaging equipment must routinely be stored outside defeats the purpose of a true hybrid operating room.

Operating Equipment

Deciding on a table that meets the needs of both surgeon and interventionalist is challenging. If fixed imaging equipment is installed, then the table also must be fixed. The table must be radiolucent, with a floating tabletop controlled by a touch panel in the surgeon’s field providing fast, fine movements during angiography, allowing the whole patient to be imaged. Carbon-fiber tables meet this requirement but do not meet the surgeon’s need for a breakable table, although some models do permit lateral and Trendelenburg tilt, and these should be selected for cardiovascular hybrid suites. Most additional positioning can be accomplished with inflatable cushions, which should be checked to establish they do not interfere with any imaging modalities. If robotic procedures are planned, then particularly careful attention needs to be paid to both working space and storage, as well as access between the two because the robot console and arms are particularly bulky pieces of equipment that are preferably stored outside the immediate area of the operating table. As the robot arms surround the operating table, it is not possible to leave the C-arm in space, and options for parking this during robotic procedures should be planned carefully in advance of installation. A fixed C-arm may not be feasible in a room in which the dominant procedure is robotic surgery.

Anesthetic Equipment

Anesthesia for hybrid procedures presents particular challenges, and careful attention must be paid to the design and ergonomics of the anesthesia area. Patients undergoing hybrid procedures may be selected because of substantial frailty or morbidity, contraindicating conventional surgery. Procedures starting out without endotracheal intubation may need urgent conversion. In addition to providing anesthesia for procedures that, in the case of transcatheter aortic valve replacement, for example, may require rapid pacing with periods of complete loss of cardiac output, the anesthetic team is simultaneously required to provide accurate transesophageal echocardiographic guidance to interventionalists. Providing real-time image guidance during time-critical parts of the procedure when the patient is often maximally unstable is a different dynamic from providing routine prebypass and postbypass imaging. Primary consideration, therefore, in designing the anesthesia area is ensuring adequate space to accommodate the anesthetic adjuncts to hybrid procedures such as transesophageal echocardiographic machines, somatosensory-evoked potential and cerebral perfusion monitoring, pacing and defibrillator devices, standard invasive monitoring, and drugs and equipment required for cardiac surgery, while ensuring the anesthesia team has optimal access to the patient at all times. The T-shaped design described earlier offers a particularly effective layout, facilitating flow to patient and equipment. Additional improvements in work flow can be obtained by creating an anesthetic room for induction; these are widely used in conventional cardiac operating rooms in Europe because they increase the efficiency with which the rooms can be used by almost eliminating anesthetic turnaround time.

Communication and Audiovisual Equipment

Imaging routing is helpful, so that all prior patient imaging can be brought up on monitoring screens, which also can display any combination of the real-time imaging or monitoring as required. Integration of multiple video inputs, such as echocardiography, angiography, film of the operative field, physiologic monitoring, electrophysiologic mapping, and live processing to produce 3D imaging, can greatly facilitate hybrid procedures but requires careful planning. Cameras may be usefully mounted high on the wall of the hybrid suite and within the central light handle, and if high-definition equipment is used with sufficient zooming and remote control capability, it can provide high-quality video footage for monitoring and education purposes. Fixed cameras can be combined with handheld thoracoscopic cameras for minimally invasive procedures. Voice-activated microphones (both fixed to the wall and mounted on headsets) are most useful for communicating with a separate control room during cardiac catheterization but also can allow the surgical team to communicate outside the operating room without breaking sterility if telephone routers are integrated. Well-planned audiovisual systems also facilitate live teaching, case discussions, and conferencing if video footage is linked to remote monitoring screens and projection centers. Dedicated Ethernet and data ports for each imaging modality, as well as standard Internet access, are necessary for uploading large image files onto hospital mainframes. Hybrid rooms should have DVD recording capability.

Opening a New Hybrid Room

Despite painstaking planning and exhaustive testing, initial wrinkles in the smooth functioning of a hybrid room are inevitable; staff need time to familiarize themselves with new layouts, equipment, and ways of working, and unforeseen challenges are inevitable. It, therefore, makes sense to ensure that, for the first week or so of operation, procedures scheduled for the hybrid operating room are routine operations with which all staff is familiar. Building complex and novel approaches in an incremental fashion should minimize adverse events and build institutional confidence in what is, by any measure, a huge investment for all concerned.