The Dedicated Endosuite

This surgeon believes that percutaneous procedures are best performed in a sterile environment.

By EDWARD B. DIETHRICH, MD
 

In recent years, treatment of vascular disease has been characterized by innovations that include balloon angioplasty, stenting, and endoluminal grafting. These minimally invasive techniques allow physicians to restore patency and flow in occluded and stenotic vessels in a wide spectrum of patients and may reduce hospital stay, expense, and recovery time as compared to open surgical procedures. Although endovascular interventions are often performed in a radiological suite or catheterization laboratory, such use of these facilities has engendered scrutiny and criticism from a variety of sources.

As the complexity of endovascular procedures has increased and more of the technology requires the use of prosthetic materials, many nonsurgical arenas are now inadequate to promote safe and efficient care. The equipment, as well as the environment, may be ill-suited for hybrid (combined endovascular and surgical) procedures or percutaneous interventions that require conversion to an open operation. The nursing and technical staff in the radiological suite or catheterization laboratory are not usually trained in the nuances of endovascular procedures and are thus unfamiliar with techniques that support the corrective actions that are sometimes necessary to ensure a successful outcome. It is difficult to argue with the premise that complex endovascular procedures are best performed in the sterile environment found in a standard operating room. Ideally, the space is fully outfitted with high-quality imaging equipment as well.1

THE DEDICATED ENDOVASCULAR SUITE
Renovation of an existing operating room or construction of a new one is extremely expensive and may present a significant stumbling block in establishing an endovascular program, however, the benefits of a proper work environment are well worth the cost. The dedicated endovascular workshop allows proper imaging and supports the physician and staff when it becomes necessary to convert quickly from a percutaneous approach to either a hybrid or open procedure. The endoluminal exclusion of thoracic aortic aneurysmal disease offers an excellent example of how the course of a percutaneous procedure can change suddenly. Figures 1-4 show a patient with a descending thoracic aneurysm in whom the lesion appeared to be ideal for corrective endovascular surgery. However, the diameter of the external iliac artery was too small to accommodate passage of the device into the abdominal aorta (Figure 1). The percutaneous route was abandoned, and a left retroperitoneal approach was used to anastomose a 10-mm Dacron endoluminal graft (ELG) to the common iliac artery just below it at the origin (Figure 2). The ELG was easily passed into the vessel and delivered into position in the thoracic aorta (Figure 3). The operation was completed with an anastomosis of the graft to the common femoral artery (Figure 4). The success of such procedures clearly depends on the skill and expertise of the staff, especially their ability to preserve the sterility of the graft. A successful procedure also relies on the availability of a proper environment and, under most circumstances, maintaining a ?standby? operating room for conversion procedures is both expensive and impractical.

Radiology suite and catheterization laboratory staff members frequently perform procedures without headdresses and masks. In the majority of cases, this sort of ?semi-sterile? approach yields no adverse consequences; however, with the introduction of endovascular techniques that incorporate prosthetic materials such as Dacron and Teflon for lining vessels, extreme care must be taken to prevent arterial infection. Although reports of infection and sepsis following endovascular procedures are infrequent, the morbidity and mortality associated with these infections is extremely high.2-24 Breaks in sterile technique are rare in an operating room environment. In one review of infection following stent placement, 21 infected cases were examined, and in all but two of these cases, stents had been placed in an angiography suite rather than in a sterile operating room.21 Although antibiotic prophylaxis has been suggested as a means of reducing the potential for infection following endovascular procedures, its efficacy in this setting has not been proven.9,11,19 A successful technical execution associated with subsequent infection exposes the patient to high likelihood of morbidity and mortality from septic complications.

DESIGNING THE IDEAL SUITE
The ideal suite (Figure 5) should comprise between 500 and 600 square feet, with a minimum clear area of 400 square feet. The primary components of the endovascular suite are the equipment for intraoperative arteriography and fluoroscopy. High-resolution fluoroscopic imaging is essential for today’s more complex endovascular procedures, particularly those involving endografting. In this setting, the accurate positioning of the covering fabric near critical side branches is assured only by quality imaging.

Imaging Equipment
There is little debate regarding a preference for the ceiling-mounted C-arm imaging equipment that is found in both cardiac catheterization laboratories and in radiology suites. Formerly, cath labs were deficient in equipment that allowed high-quality lower extremity imaging, but the latest generation of equipment has overcome some of the shortcomings of earlier models. Nevertheless, many cath labs are still not equipped with the capacity for “roadmapping,” in which substrated images permit real-time visualization. This function increases both the accuracy and efficiency of angioplasty maneuvers.
In the surgical arena, there is a paucity of ceiling-mounted imaging equipment. Most surgical units rely on portable C-arms, which have the advantage of mobility for use in multiple rooms and procedures. Unfortunately, these units are less user-friendly than stationary C-arm equipment, and it is more difficult to pan the length of the pelvis and lower extremities using mobile equipment. Although the newer portable C-arms do have roadmapping capabilities, it can be frustrating to find that the mobile unit is in use in another operating room when it is needed for the endovascular procedure.

The Right Table
In addition to the appropriate fluoroscopic unit, a nonmetallic, carbon fiber surgical table is essential for peripheral endovascular interventions. Cardiac procedures are usually limited to a small window over the chest, whereas the peripheral cases may require visualization from the antecubital space to the ankle. Our suites are equipped with nonmetallic, carbon fiber tables that are supported at only one end and provide complete clearance for panning x-rays. This capability has proven particularly useful when it is necessary to pass a brachial-femoral wire into position for delivery of endovascular grafts. The ability to move quickly over the area without interference from the table is invaluable in such procedures.
Visualization Techniques

We use intravascular ultrasound (IVUS) techniques in almost all abdominal and thoracic endograft procedures, because they provide baseline luminal dimensions and precise determination of arterial architecture and lesion pathology. IVUS has become indispensable when CT images are such that the interventionist has difficulty assessing the proper stent size. In many cases, IVUS examination following balloon dilation also helps define the need for further intervention. The most important application of this technology, however, is when assessment of the lumen of the artery is required, such as in cases of aneurysmal disease or vessel dissection. IVUS is the most precise method of determining arterial diameter and for visualizing the origins of a dissection, the extent of disease, and the orifices of branching vessels. In addition, the advent of color flow IVUS provides the potential to determine the presence of endoleak. This new ability may make IVUS even more important in procedural and postprocedure evaluations.
Angioscopy is also useful, offering direct visualization of suture lines and lumens of grafts. Although it is used less often than ultrasound, this is an important tool for assessing the superficial femoral artery and the popliteal artery and its trifurcation. For example, an angioscopic assessment is an extremely accurate means of determining the extent of obstructing plaque and aids the interventionalist in planning a device deployment strategy. In our experience, angioscopy allows a real look at disease and is much more informative than contrast studies. It also allows evaluation of hemorrhagic plaques and intimal hyperplasia in stents.

Patient Monitoring
The endovascular suite must be equipped for accurate patient monitoring during the procedure; continuous electrocardiographic surveillance is imperative. Observation of urine output is also essential for cases involving the renal arteries and higher abdominal or thoracic aortic segments. Intra-arterial monitoring that includes precise measurement of pressure differentials is also important during endovascular procedures.

ENDOVASCULAR DEVICES
There are a variety of sheaths, catheters, wires, and balloons available today. It is now possible to perform most standard angioplasty procedures, including stent deployment, through sheaths <7F (or even <6F); such devices are available from many companies. Hydrophilic-coated guidewires have greatly increased the ease and safety of lesion traversal, and high-resolution fluoroscopic equipment assures better positioning of all wires and devices. Steerable guidewires are also available, as are ?activated? wires that allow the interventionist to navigate severely occluded vessels. Balloon technology has improved considerably, yielding low-profile devices with excellent performance capabilities. For peripheral interventions, catheter lengths from 65 cm to 150 cm are commonly inventoried for a variety of balloon dimensions. Longer lengths are available for retrograde procedures in which the aortic bifurcation is crossed in order to reach the contralateral limb. Useful balloon diameters range from 4 mm to 8 mm, over lengths of 2 mm to 10 mm for angioplasty procedures. Larger balloons up to 40 mm are now available for thoracic endovascular interventions.

Stenting Options
A variety of stents are available in both balloon-expandable and self-expanding designs. Balloon-expandable devices provide longitudinal rigidity and diameters that make them ideal for straight vessels such as distal aorta, mesenteric, renal, and iliac arteries. The spring-like structure of the self-expanding stent makes it useful for delivery through curved arteries, implantation overlying the graft-artery junction in end-to-side anastomoses, and in vessels subject to flexion from adjacent joints or structures.

In 2002, Cordis Corporation (a Johnson & Johnson company, Miami, FL) introduced the Palmaz Genesis stent, which is a new balloon-expandable device incorporating high radial strength to resist vessel recoil and flexibility that accommodates tortuous or challenging anatomy. The stent offers minimal stent shortening and may be delivered through a very low profile sheath; it is available premounted or unmounted. The Smart Stent, also available from Cordis, is a self-expanding nitinol stent that has a flexible, segmented design. Both stents are considerably more flexible than the original Palmaz designs that were commonly used in the past. The Wallstent (Boston Scientific Corporation, Natick, MA) is a self-expanding stent that we have used most commonly in carotid angioplasty protocols. Alternatively, the VistaFlex stent (Angiodynamics Inc., Queensbury, NY) is a balloon-expandable stent comprised of platinum in a linked segment design that is highly visible and MRA compatible. Bridge Stents (Medtronic AVE, Santa Rosa, CA) are also available in extra support and flexible designs; both are balloon expandable and offered in a variety of lengths. The Herculink Biliary System (Guidant Corporation, Indianapolis, IN) includes a low-profile, highly trackable stent that provides differential radial strength. IntraStent (IntraTherapeutics, Inc., St. Paul, MN) is another balloon-expandable stent that is 6F compatible when used with a low-profile 5F balloon; its cell structure provides robust radial force.

Endoluminal Grafts
Endoluminal grafting now plays a significant role in the treatment of aneurysmal disease. The first two commercial products approved in the US were the Ancure device by Guidant and the AneuRx device by Medtronic. Other devices, such as the Talent graft by World Medical/Medtronic (Sunrise, FL), have been used widely in Europe, and clinical trials are ongoing with the Zenith graft (Cook Incorporated, Bloomington, IN), the Endologix graft (Endologix Inc., Irvine, CA), and the Lifepath graft (Edwards, Irvine, CA). Most recently, the FDA has approved the Excluder graft (WL Gore & Associates, Flagstaff, AZ). The Teramed graft was purchased by Cordis Endovascular and is now called the Ariba graft. There are currently no thoracic devices approved in the US despite the fact that numerous thoracic pathologies can be treated effectively with the technology.

AN ENVIRONMENT FOR SUCCESS
Endovascular surgery is a technology-driven specialty that incorporates sophisticated imaging techniques and innovative equipment. While there are differences of opinion regarding the ideal environment for performing these procedures, many endovascular interventions are still completed in radiographic suites. My experience over more than 30 years has convinced me that a dedicated endovascular suite that allows optimal imaging and strict adherence to the sterile conditions is preferable. Although there is considerable expense associated with construction of such a facility, the properly designed and equipped endovascular suite offers the greatest likelihood for successful endovascular intervention using current techniques, and it supports the clinical team in developing the procedures of the future.

Edward B. Diethrich, MD, is Medical Director at the Arizona Heart Institute and Arizona Heart Hospital in Phoenix, Arizona. Dr. Diethrich is a stockholder in Endologix. He may be reached at (602) 266-2200; ediethrich@azheart.com.

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About Endovascular Today

Endovascular Today is a publication dedicated to bringing you comprehensive coverage of all the latest technology, techniques, and developments in the endovascular field. Our Editorial Advisory Board is composed of the top endovascular specialists, including interventional cardiologists, interventional radiologists, vascular surgeons, neurologists, and vascular medicine practitioners, and our publication is read by an audience of more than 22,000 members of the endovascular community.