The Digital Cath Lab: Exploring New Depths
Newer technologies hitting the market for use in the cardiac catheterization lab include advanced digital imaging systems, drug eluting stents and perfusion balloons. The combination of imaging, diagnostic and therapeutic technology is improving the detection and intervention of cardiac disease. And the newer generations of angiography systems utilize flat-panel detectors that tout superior imaging quality and more efficient radiation dose.Many thousands of cardiac catheterizations are performed everyday by cardiologists to diagnose and treat cardiac disease, especially coronary artery disease.
Depending on the severity of a patient's case, treatment may include angioplasty and stenting, as well as coronary artery bypass surgery. Accurate, high-quality images are imperative in determining the optimal path of therapy for each patient. Tiny blood vessels of the heart are hard-to-see, and its minute moving structures require an imaging system with finite resolution and distortion-free imaging techniques.
Approximately one-third of patients with coronary artery disease will undergo coronary angioplasty and stenting. At the Cardiac Cath Lab at North Shore University Hospital in Manhasset, N.Y., 1,200 cardiac caths are performed each month. "We do 4,200 cardiac interventions and 10,000 diagnostic cardiac cath procedures on an annual basis," says Stanley Katz, MD, chief of cardiology at North Shore University Hospital, which is part of the North Shore-Long Island Jewish Health System.
"I think that if you look at the outcomes of angioplasty and stent procedures worldwide, there has been a dramatic improvement in morbidity and mortality, as well as the treatment in myocardial infarction patients," says Katz. "When we started doing angioplasties in the '80s, there was a 5 to 7 percent failure rate requiring urgent bypass surgery. That [failure rate] is about zero to 0.5 percent now. I think this is due to improved skills of the physician, but more importantly through improved products such as balloons, wires, stents and x-ray equipment."
The new market player
Cath lab vendors now offer user-friendly, diagnostic and interventional angiography systems that are coupled with high-quality, flat-panel detectors (FPD), as opposed to image intensifiers. The technology touts superior image quality and greater dose efficiency. Flat panels produce distortion-free images with uniform brightness for patients of all sizes - an important component in the cath lab since obesity is a major contributor to heart disease.
Leading system vendors include GE Healthcare, Toshiba America Medical Systems, Siemens Medical Solutions and Philips Medical Systems. Vendors offer systems dedicated to cardiac procedures, systems with larger FPDs to perform cardiac and peripheral exams, as well as dual-plane systems that integrate two C-arms into one system to optimize imaging for cardiac and peripheral angiography studies. Dual-plane systems typically consist of dedicated C-arms for cardiac and peripheral procedures that share a common table, generator, digital acquisition system and monitors. The desire to work outside the heart has been and is a significant trend in the cardiology market.
North Shore's state-of-the-art, seven-room cath lab department will soon expand to nine by the end of the year, says Katz. All of the labs are equipped with single-plane systems and eight of the nine systems have flat plates.
GE's Innova 2100 IQ, the company's newest digital cardiovascular diagnostic and interventional imaging system, has a 20-centimeter FPD. North Shore uses the system strictly for cardiac procedures. For peripherals, the facility installed GE's Innova 4100 that has a 41-cm FPD. "We do quite a bit of peripherals on the 4100," says Katz. "We have gradually increased volumes of peripherals. That is why we got the 4100." Two of the labs are awaiting installation of GE's Innova 3100 that has a 30-cm FPD, which will be used for both cardiovascular and peripheral studies.
While peripheral work in the cath lab is a growing trend with promising outcomes for patients, it has created a bit of friction between cardiologists and interventional radiologists. "Five years ago there was a civil war between the cardiologists and the radiologists and vascular surgeons," say Katz. "It was resolved with the installation of a system that could image [areas outside the heart]."
Five years ago, a defining moment took place at North Shore that determined the cath labs would operate using FPD technology. "There was a 280-pound patient in his late 40s who had a diagnostic angiogram," describes Katz. "Using the [conventional] system, he was found to have triple vessel disease and bypass surgery was recommended. However, the patient did not want surgery because he wanted stents. He asked if I would put stents in him. I said that I would like to [image him with] the flat-panel system and if I could visualize what was seen on the conventional system, I would attempt to do stents. We took him into the flat-plate detector room where I was able to see much better and place the stents in all three vessels. Now five years later, the patient continues to do well. That was the leap from the image intensifier tubes to the digital flat-panel detector technology."
FPD systems offer users a range of new applications. Auto-countouring, an application available on GE's Innova 2100 IQ, senses the patient and brings the flat-panel detector in as close to the patient as possible without colliding with the patient, producing better images and less scatter of radiation. "The auto-contouring is an amazing feature," says Katz. "It drastically reduces the amount of x-ray scatter to everyone else in the room. It brings the detector as close as it should be to the patient so that you get the best possible images. The next advantage [of FPD technology] is the enhanced image quality, especially during fluoroscopy." Cardiologists can better visualize stents and wires when performing interventional procedures.
The lab is fully equipped with GE's Mac-Lab IT, which consists of a Mac-Lab hemodynamic monitoring system and Centricity Cardiology data management system. The labs also are linked to a remote archiving system. The intricate level of networking and connectivity will eventually allow cardiologists to remotely access electronic cath lab images and reports. "Our ultimate goal, which we hope to achieve in about a month, is that the cardiologists will be able to access the cath reports as well as the cath images anywhere that they have internet access," explains Katz.
The labs also are linked to a multislice CT scanner. Cardiologists can retrieve the voluminous CT data sets directly in the cath lab control room. "Cardiologists can compare the CT images with the cath images to get a much better understanding of the lesions," says Katz. "Cardiologists can probably do a better job in terms of stenting because the CT will reveal how extensive the lesion is much better than the cath does."
Seeing more detail
Cardiologists are seeing greater detail with the flat-panel detector technology utilized at University of North Carolina Hospitals, too. The healthcare organization's cath lab implemented Toshiba's Infinix CC-i/FD cardiac ceiling mounted system that comes equipped with an 8-by-8 inch FPD. Dedicated to cardiac imaging, the system is used for approximately 120 cardiac cath procedures monthly, says Mauricio Cohen, MD, associate director of UNC's catheterization laboratory.
Distortion-free cardiac imaging is one benefit of the flat-panel technology. "With the system, we avoid geometric distortion," says Cohen. "The images are very accurate. For example, if I have to do quantitative coronary angiography to estimate the size of a vessel that I want to stent, I am never concerned about getting inaccurate measurements."
Flat-panel detectors, which record dynamic and static x-ray images at a high image quality, have improved contrast and spatial resolution that makes the visualization of fine guide wires, markers and stents much easier. "It's all live, so we really rely on the images we see to make accurate decisions," says Cohen. "To do an intervention, we thread a wire through the blockage and then advance a balloon over the wire. The wire is fourteen thousandths of an inch. Its very thin and we need very good dynamic resolution to see the wire. At the same time, we need very good uniformed spatial resolution.
"The flat-panel detector provides good quality images with uniform grays," continues Cohen. "We are able to visualize the very thin wire. Sometimes when we deliver the stent, we have to make sure that we do it appropriately. The coronary vessels can be in between 2.5 and 3.5 millimeters in diameter and they move. With our calculations, we sometimes need to say whether we are going to bring a 3.25 mm balloon versus a 3.5 mm or a 2.75 mm stent versus a 2.5 mm or 3.0 mm stent. Our decision-making sometimes goes to a quarter of a millimeter in terms of what size stent we are going to use."
Using flat panels also can bring the advantage of lower radiation dose to the patient, the clinicians and the technologists present in the exam room. "With a coronary intervention, most of the radiation is not due to image acquisition, but due to just plain fluoroscopy," says Katz. "When we advance a stent, we are using fluoroscopy. The flat-panel detector gives us very good quality fluro. Depending on the level of fluoro, we may get between 27 and 60 percent less radiation with the flat-panel detector."
After cath procedures are completed, the cardiologists generate a report and the images are transferred to a digital storage system. The archiving system permits cardiologists to access cath lab images from different workstations located throughout different parts of the cath lab. "We also have a web-based server, so [authorized users] can actually look at the images from anywhere via the internet," says Cohen.
Connecting the pieces
Erecting a cath lab in late 2004, Methodist Willowbrook Hospital in Houston installed Siemens' Axiom Artis dTA single plane C-arm system. Lyle Muhammad, cath lab manager, says the ceiling mounted lab is "multidisciplinary" since the system can be used for both peripheral vascular and cardiovascular work. The system is equipped with a 30-by-40 inch FPD.
Cardiologists primarily use the system, but interventional radiologists are the other group of physicians who make use of it as well. "If we had more than one room, one room would be designated to the cardiac cath lab and the other room would be called a special procedures suite," says Muhammad. "Since we don't have that at this point, and since we only have the one room, it has to be shared by interventional radiologists and cardiologists."
Methodist's involved level of connectivity allows cardiologists to simultaneously view multimodality cardiology images. Methodist utilizes a Siemens' KinetDx CWS3000 cardiology workstation that stores echo images until they are archived to the department's long-term storage system. Cardiologists can retrieve the echo images into the Artis lab for review during the cath procedure.
"Echocardiograms can now be viewed within the cath lab," explains Muhammad. "As soon as the cardiac cath procedure is completed, cardiologists can acquire the digital images on Siemens' Axiom Sensis Report Workstation. On site at the hospital, there is an interface that connects both the KinetDx workstation with the Sensis workstation. As a result, no matter which workstation the cardiologist is at - whether the workstation is in the echo lab or the cardiology department - the doctor can simultaneously review cardiac cath and echo procedures."
The lab also is equipped with Siemens' Sensis Hemodynamic and Electrophysiology Reporting system. "This workstation and the Sensis reporting workstation are about a desk away from each other," says Muhammad. "One is set up on a platform that helps the physicians get done what they need to get done. The other one is set up in a way where it acquires a certain amount of information that satisfies the needs of the department. Then, the hemodynamic and EP workstation sends the information that the physicians need to complete the report into the reporting workstation."
Once a physician completes a cath report, it is exported out into the hospital's electronic record system. "We are now on electronic hospital charts as well," says Muhammad. "The virtual chart can be viewed by authorized users throughout the hospital-wide enterprise."
The IT-oriented environment has streamlined the information acquired during each diagnostic and interventional cath procedure. "Users are not performing newer procedures, but rather, users are working in a much more efficient environment," says Muhammad. "With electronic image and information systems, it is much easier to share the information, process the information, acquire the information, review the information and store the information. These are all of the advantages to going digital."
Conclusion
Angiography plays a fundamental role in the detection, diagnosis and treatment of heart disease, heart attack, acute stroke and vascular diseases. Hardware and software improvements made to the imaging component of cath procedures are helping physicians visualize structures more clearly during interventional exams, as well as expanding possibilities in the area of peripheral angiography. Flat panels are a trend whose time has come, and the technology offers better imaging quality over older systems, as well as better dose management and ease of maneuverability. As more flat-panel systems are adopted, will continue to focus on networking and connectivity so that cath lab images and information can be distributed throughout the healthcare enterprise.
According to UNC's Cohen, the cath lab may be used for more interventions than diagnostics in the future due to improvements in CT angiography. "As CT angiography gets better every day and the images are used more widely, I think in the future this non-invasive technology may replace diagnostic catheterization," says Cohen. "But CT angiography is not ready yet. However, a few years ago we were not talking about CT angiography and now we are. In a few years, I think that we are going to see a lot of improvements to CT angiography." For patients, this means better methodologies for detecting and treating various forms of heart disease.
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| Navigating the Digital Cath Lab Options | ||||
| State-of-the-art cardiovascular digital imaging systems are coupled with flat-panel detectors that bring the benefit of excellent image quality and lower dose. Cardiologists can see miniscule blood vessels with exceptional clarity on flat panel-acquired images, and clearly visualize interventional devices for the accurate placement of stents, guidewires and catheters. As the field explores angiography outside the heart, vendors have expanded their suite of flat-panel angiography systems to include systems suitable for either cardiac or peripheral, and in some instances, both. | ||||
| Company & Model | Type | Flat Panel Detector | Field of View | Applications |
| GE Healthcare | ||||
| Innova 2100 IQ | single plane, floor mounted | 20x20cm | 20cm, 17cm, 15cm, 12cm | Primarily cardiovascular diagnostics and interventions, but also used for vascular |
| Innova 4100 | single plane, floor mounted | 41x41cm | 40cm, 32cm, 20cm, 16cm | Primarily vascular diagnostics and interventions, but also used for cardiac |
| Innova 3100 | single plane, floor mounted | 31x31cm | 30cm, 20cm, 16cm, 12cm | Cardiac and vascular diagnostics and intervention |
| Philips Medical Systems | ||||
| Allura Xper FD10 | single plane, ceiling suspended or floor mounted | 7''x7'' | 10''x10'', 8''x8'', 6''x6'' | Cardiovascular diagnostics and intervention, electrophysiology |
| Allura Xper FD20 | single plane, ceiling mounted | 12''x16' | 12''x16'', 12''x12'', 8''x8'', 6''x6'' | Shared cardiovascular and vascular diagnostics and intervention |
| Allura Xper FD10/10 | biplane system | 7''x7' | 10''x10'', 8''x8'', 6''x6'' | Electrophysiology, pediatric cardiology |
| Siemens Medical Solutions | ||||
| Axiom Artis dBC | floor & ceiling mounted C-arm stands | 30x40cm or 20x20cm | 30x40 FPD: 48cm, 42cm, 32cm, 22cm, 16cm, 11cm | Cardiovascular diagnostics and intervention |
| Axiom Artis dFC | single plane, floor mounted | 30x40cm or 20x20cm | 30x40 FPD: 48cm, 42cm, 32cm, 22cm, 16cm, 11cm | Cardiovascular diagnostics and intervention |
| Artis dTC | single plane, ceiling mounted | 30x40cm or 20x20cm | 30x40 FPD: 48cm, 42cm, 32cm, 22cm, 16cm, 11cm | Cardiovascular diagnostics and intervention |
| Toshiba America Medical Systems | ||||
| Infinix CC-i | single plane, ceiling mounted | 8''x8'' | 8''x8'', 7''x7'', 6''x6'', 5''x5'' | Cardiovascular diagnostics and intervention |
| Infinix CS-i | single plane, floor mounted | 8''x8'' | 8''x8'', 7''x7'', 6''x6'', 5''x5'' | Cardiovascular diagnostics and intervention |
| Infinix DP-i | dual-plane system | cardiac plane: 8''x8'' angio plane: 12''x16'' | cardiac plane: 8''x8'', 7''x7'', 6''x6'', 5''x5'' angio plane: 12''x12'', 8''x8'', 6''x6'' | Shared cardiovascular and vascular diagnostics and intervention |