As coronary diseases continue to proliferate, diagnostic cardiac catheterization procedures are keeping pace. To increase efficiency, some facilities have opted for cardiac cath swing labs, which use one C-arm that pivots between two tables. But despite the configuration’s potential for increased productivity, users and manufacturers say it is a niche market that is not right for every, or even most, facilities.

But a new type of ‘swing’ lab has physicians — from cardiologists to neurologists — sitting up and taking notice. The suite combines magnetic resonance imaging (MRI) and x-ray systems to improve diagnoses and to shorten the time between diagnosis and treatment, saving critical time for stroke and coronary patients. The combination may even change how physician’s approach healthcare, blurring the lines between diagnosis, treatment and evaluation. But research is just getting under way, and the expensive systems exist in just a few large academic research institutions.

Swinging C-arms
“A swing lab can be a great lab depending upon who’s using it and what he or she is using it for,” says James R. Wilentz, M.D., F.A.C.C., director of cardiac catheterization laboratories and interventional cardiology at St. Luke’s — Roosevelt Hospital Center (New York).

The little-known swing lab (in the U.S. anyway, while overseas interest is more keen) essentially converts one cath lab into two by using a single C-arm that pivots, or swings, between two x-ray tables separated by a movable lead-lined wall. While a physician performs a procedure on one side, nurses prepare the next patient on the other table. After the first procedure finishes, nurses swing the C-arm to the other side, saving about 30 minutes in preparation time for each procedure.

Five years ago, Wilentz helped install and now uses the swing lab at Beth Israel Medical Center (New York). The Toshiba lab is one of three cath labs at Beth Israel, where physicians perform more than 1,000 interventional and 3,500 total angiographic procedures a year.

When cath lab procedures move along predictably, swing labs can double the workload of a single lab. But that does not always work out, Wilentz says. Nurses rely on knowing the length of each procedure so that they can schedule patients appropriately and prep them in time for the next procedure. While diagnostic cases offer that predictability, patients and nurses are left waiting when cases turn into interventional procedures.

“The experience at Beth Israel has been that when they’re doing caths, and a lot of them turn into angioplasties, the swing lab is essentially wasted real estate,” Wilentz says. “If you counted on being able to have the throughput that a swing lab can give you, but you don’t have control over the schedule, then you can end up at the end of the day with patients either left over or canceled or just disgruntled from long waiting periods.”

St. Luke’s high rate of interventional procedures was the main reason Wilentz and colleagues opted not to include a swing lab in their recent purchase of two new cath labs.

Wilentz says for facilities doing both diagnostic and interventional cases, especially with a large base of out-of-town patients who find it inconvenient to return for treatment later, swing labs are impractical. “But if you’re running a diagnostic outpatient cath center, that would probably be a very good place for a swing lab,” he says. “In a lab where the schedule is predictable, a swing lab can be fabulous.”

But, Wilentz advices, “if you are going to use a swing lab, the key is controlling the schedule and having a manager who can ride the schedule like a bulldog, making sure the nurses are swinging to the other side at the appropriate time.”

Rebekah Surles, B.S., RT(R), cardiovascular specialist, at the Heart Center of WakeMed (Raleigh, N.C.), says their Philips swing lab, installed in 1998, was a popular addition. “We like it a lot,” she says. “It’s easy to keep the doctor moving.” Physicians perform both diagnostic and interventional cases in the swing lab, but staff schedule patients in a way to keep things moving. At times, unexpected interventional cases can cause long delays, but Wilkes says having the other room already set up still saves time. The center’s swing lab typically handles 10 to 12 cases a day, twice the number of their single C-arm cath lab.

Few vendors offer a swing lab, and those that do admit it is a small, niche market that can be difficult to sell. “In a perfect world, if someone has a steady, large stream of nothing but diagnostic procedures and there are no emergencies and no need to do work outside of the heart, a swing lab works very well,” says Raymond Dimas, senior product manager — vascular systems at Toshiba America Medical Systems (Tustin, Calif.).

But Dimas admits that perfect swing lab world is rare and interest has been low. As heart centers proliferate, the competition for patients becomes keener, creating an even greater incentive not to keep patients waiting through emergency interventions. Dimas also says Medicare reimbursements steer facilities away from swing labs. “With the high reimbursement rates of interventional procedures, for a facility that needs to pay off a lab, interventional procedures can be critical to maintaining a heart program,” he says.

“For about the same price as a swing lab, they can get two dedicated labs and not have to have the concern of emergency interventions coming into play and slowing down their patient throughput,” Dimas adds.

Sandy Black, cardiac product manager at Siemens Medical Solutions Inc. (Iselin, N.J.), agrees that swing labs are a niche market. But as the overall cath lab market grows, the swing lab market also grows, albeit more slowly.

Keeping the market down, in addition to surprise interventions, is the swing labs’ larger size, Black says. Many facilities cannot accommodate the larger space required. The lab also functions differently so staff must be trained, and not everyone is comfortable working with the unique system.

But Black says that the lab can be particularly helpful for facilities in states that require a Certificate of Need (CON) to operate a cath lab. For high volume centers that can obtain only one CON, a swing lab can increase their efficiency.

Both Dimas and Black say that combination labs are more popular options than swing labs. Physicians increasingly are welcoming vascular work beyond the heart, and they want a system that can handle both cardiac and peripheral work. Originally designed for smaller hospitals that had one lab to perform both cardiology and radiology procedures, some combo labs use one image intensifier at a size somewhere between the 9-inch cardiac image intensifier and the 16-inch or larger intensifier normally found in interventional radiology.

St. Luke’s Wilentz says one of the two new cath labs his department recently purchased was Toshiba’s Infinix Dual Plane, a combination lab with two C-arms, a 9-inch image intensifier for cardiac work and a 16-inch image intensifier for peripheral work. The C-arms share a common table, x-ray generator, and digital fluoroscopy system.

Brave New World
Despite St. Luke’s new cath labs, Wilentz says they may become extinct soon. “We’re just about to enter a world where diagnostic imaging is going to move toward non-catheter based modalities,” he says. “Which is the likely winner, we don’t know. But diagnostic cardiac catheterization for the purpose of visualizing the coronary angiogram is going to be obsolete at some point in time.”

Some manufacturers are helping speed diagnostic cardiac cath’s demise by developing new labs that combine modalities to give physicians even greater flexibility. Some computed tomography (CT) and x-ray labs exist, but of greater interest to U.S. physicians is the combination MRI and interventional x-ray lab. Cardiac care is only one area this combination of modalities may transform.

GE Medical Systems (GEMS of Waukesha, Wis.) introduced its prototype XMR system in March 2001, now installed in three academic institutions. The XMR uses a detachable table that can be attached to both the x-ray scanner and the MR system. “This allows us to transport the patient from the MR to the x-ray and vice-versa without the patient having to be removed from the tabletop, which is really essential when you’re doing these procedures and you have catheters in place and so forth,” says David Weber, Ph.D., GEMS’ manager of the global high-field MR business.

The GEMS XMR is demonstrating its power in the ability to diagnose and treat stroke patients under the guidance of Gilberto Gonzalez, M.D., Ph.D., director of neuroradiology at Massachusetts General Hospital (Boston), who has done the most work with the GEMS XMR.

“The potential result of a stroke is devastating — death or severe disability,” says Gonzalez. “We do have a treatment. However, the time that we have to be effective with that treatment is quite short.” To best assess the brain, Gonzalez uses perfusion MR, but treatment requires high-quality angiography. “Currently, they’re in separate rooms and in separate parts of the radiology department,” he says. “We can’t effectively do it. That was the motivation to actually put them together in the same room.”

Being able to assess the brain using the XMR leads to a faster, more accurate triage decision, Gonzalez says. Additionally, the combination lets him use MR imaging to assess the brain during the interventional procedure. Real-time MR information makes the procedure more effective and safer, increasing efficacy from 60 percent to 80 percent and reducing hemorrhage rates from 20 percent to well below 10 percent, Gonzalez estimates.

“It worked spectacularly well,” Gonzalez says of the few times he has used the new system on patients, crediting the XMR table for its success. Normally, x-ray and MR tables cannot be used interchangeably. But the mobile XMR table, equipped with monitoring tools and contrast ejectors, is.

Combining MR assessment with x-ray angiography to diagnose and treat strokes will eventually become state-of-the-art and major medical centers will have to jump in and use it, says Gonzalez. Although expensive, the system is paying for itself because the MR portion is being used alone as well.

Gonzalez says stroke treatment is just one possible application. “We’ve been keeping the cardiologists away from it,” he says with a laugh. “But if it’s useful in coronary artery disease, then the whole thing cracks open and you’ve sold this to every hospital with more than 200 beds in the country. This could have a very major impact. Between the brain and the heart, that covers the No. 1 and No. 3 killers in the country.”

Hitting the Top Three
Even the No. 2 killer, cancer, is not immune to a combined MR and x-ray system, says Peter Luyten, Ph.D., senior director for MRI business development at Philips Medical Systems (Bothell, Wash.). Philips installed their XMR suite at the University of California-San Francisco (UCSF) in July 2001. The system uses Philips’ 1.5 tesla I/T MRI scanner with the Integris Vascular angiography system.

When designing the XMR, Luyten says one requirement was to build it like a swing lab. A sliding shielded door can separate the two components so that physicians can use each modality independently. At UCSF, the suite functions half the time as separate rooms.

But the real benefits come when the door opens and the modalities are combined. “You have the ideal environment of really driving the whole field to a new source of applications,” says Luyten. “You get much better functional information about the procedure that you have actually performed.”

In cancer treatment, for example, physicians treat liver tumors by injecting a drug through a catheter slipped in through the groin and up to the liver using an x-ray system. By adding MR imaging at the time of delivery, physicians can see where the drug is absorbed and can adjust the treatment at the time, instead of having patients return over a period of weeks to evaluate and redeliver treatment.

For hearts, physicians can place a stent using x-ray guidance then use the MR system to measure the blood supply to the tissue, adjusting the stent as necessary.

Both GEMS’ Weber and Philips’ Luyten say that combining modalities is an expensive setup that is limited to a few large academic institutions. Siemens’ Black and Toshiba’s Dimas say they do not believe most facilities are ready for the expensive suites.

“There are inherent limitations as far as payoffs with patient throughput,” Dimas says. “Because it’s such a large investment, any downtime in the room makes it difficult for a hospital to afford it. Combining MR and vascular or CT and vascular still doesn’t meet the economic needs and requirements of a hospital.”

St. Luke’s Wilentz agrees. When his department was preparing to purchase new cath labs, Wilentz says they enthusiastically contemplated an MR/x-ray combination system. “It’s a very good concept,” he says. “The problem is right now it’s just tremendously expensive.” An XMR suite would have cost $2 million, twice the cost of their dual C-arm cath lab.

In addition, devices that can be used with both MR and x-ray systems still are being developed. Luyten says device development is the biggest issue yet to be resolved to insure the XMR concept’s success. Creating such devices requires the cooperation of imaging companies, the device industry and physicians — a coalition that has already formed.

In the future, physicians and manufacturers believe the XMR suite may put itself out of business. By moving back and forth between modalities, physicians may more easily learn to perform MR-guided interventional procedures. “In that setting, the XMR concept could be an interim device to developing MR into the final interventional device,” says Weber.

Massachusetts General’s Gonzalez agrees, saying he envisions his work with the XMR to help lead to a future of MR-only applications, but cautions that day is a long way off.

Luyten says healthcare is facing a whole new era in which patients will be immediately run through a series of diagnostic imaging modalities for faster, more efficient triage. Using MR-only interventional procedures will create a “health cascade of one-stop shop procedures” he says.

The combination x-ray and MR suites may be the answer to shrinking that time span between diagnosis and therapy while increasing treatment efficacy and ultimately enhancing patient quality of life.