Advancing Treatments at the George Washington University Hospital

Jay A. Mazel, MD
Jay A. Mazel, MD
EP Lab Digest recently spoke with Jay A. Mazel, MD, from George Washington University Hospital in Washington, DC, regarding upcoming advances at GWU. One of the new advancements involves utilizing a new multiple therapy pacing system for the treatment of complex heart rhythm disturbances. The AT500 Pacing System by Medtronic is a new system that uses multiple features to monitor atrial arrhythmias and deliver therapies that may stop or suppress atrial tachyarrhythmias and catheter-based procedures to cure them. In this article, he also describes the new GW Women's Heart Program, which is exclusively dedicated to preventing, diagnosing, and treating cardiovascular disease in women. The George Washington University Hospital has committed itself to providing some of the best patient care in the nation. Located in the heart of the nation s capitol, GWU Hospital is known for its advancements in the medical field. Treating high-profile patients such as Vice President Dick Cheney, as well as foreign dignitaries, they have based their principles on using the most advanced medicine offered. Recently, the GWU Hospital was the premier hospital to use a new multiple therapy pacing system for the treatment of complex heart rhythm problems. The AT500 (Medtronic, Minneapolis, Minnesota) system is a revolutionary way to treat heart rhythm problems. Currently more than 2 million Americans suffer from atrial fibrillation. The AT500 is a pacemaker with two leads, one for the upper chamber of the heart, and one for the lower chamber. The leads are connected to a small box, which is implanted underneath the collarbone. Physically, the device is similar to other pacemakers, however, the AT500 comes with new therapies used in the hopes of better treating atrial fibrillation (AF). With the AT500 pacemaker, it is hoped that certain types of pacing algorithms will actually be able to suppress fast heartbeats. Normally, pacemakers are thought of as devices that prevent slow heartbeats, but this pacemaker s algorithms help control certain fast heartbeats from either occurring in the first place, or when they do happen, treating those rhythms and restoring the heart rate back to normal. There are three algorithms of the AT500: atrial preference pacing (APP), atrial rate stabilization (ARS), and post-mode switch overdrive pacing (PMOP). Typically, the rhythms of the heart are generated by the natural pacemaker system in the heart called the sinus node. About the size of a pea, it is located up on the top of the heart, and generates electrical impulses. The impulses are distributed through the rest of the heart, so that each cell in the heart is stimulated by this electrical impulse. Every time the heart beats, it is responding to a signal from the sinus node. This process is similar to how muscles in the body function. An electrical impulse is sent to a muscle from a nerve, and the muscle contracts when an arrhythmia occurs. When other places in the heart besides the sinus node begin generating impulses of their own, it forces the heart to beat faster than it naturally does. Some arrhythmias are life threatening, while others are fairly benign. The AT500 uses the impulses it generates to suppress certain places in the heart from generating their own rapid impulses. APP works by denying the heart the ability to generate its own impulses from the normal sinus node. Instead, it takes over the pacing of the heart entirely by pacing the atrium. The idea is, that often times AF occurs when the natural pacemaker of the heart starts to weaken and become diseased. Suppressing or pacing the atrium has been found to significantly reduce the atrial fibrillation as it occurs. APP provides an overdrive pacing at a slightly faster rate than the basic sinus rhythm, resulting in an increased pacing time. This creates a consistent rhythm in situations of abnormal atrium movements. APP will maintain a pacing rate close to that of basic sinus rhythm. Sometimes one of the other triggers of AF is rate irregularity. If the impulses that are being generated are not regular like a clock it can become a factor in causing AF. ARS senses APB gradually adjusts the rhythm interval until the regular atrial rate is achieved. This eliminates any pauses or other events that may trigger AF. PMOP is a feature than may prevent recurrences of AF. The pacemaker can sometimes temporarily overdrive the pacing of the heart after normal rhythm returns. For example, if a patient has just gone through AF, and normal rhythm has occurred, PMOP can take over the pacing of the heart more rapidly to inhibit a recurrence of AF. The AT500 can also help terminate episodes of AF once they occur. Like other products on the market, the AT500 is useful in reducing the number of episodes a patient has, though not curing them of atrial fibrillation. Other devices do have certain features which function similar to the AT500. However, the ARS feature that Medtronic has developed is a feature on the market that is exclusive to this device. PMOP is also a unique feature that is not seen on other manufacturer s devices. One of the main advantages of this system is its ability to catch silent episodes. Commonly, patients are not aware of certain symptoms of AF or other irregular rhythms. This pacemaker, however, can sense even slight episodes, and treat them accordingly. With the device implanted in the patient, it is like having a 24-hour monitor on their heart. The AT500 can provide a detailed report of episodes including time, duration, and the kind of rhythm that occurs. This enables the physician to see when episodes occur and then adapt a treatment program or medication accordingly. At George Washington University Hospital, we also perform complex ablations, where we actually cure some of these rhythms. GWU Hospital is also performing some atrial fibrillation ablations, during which a catheter is thread up through the heart to look for the spots that are generating those abnormal heart pulses, and actually cure them with a catheter, so the patient does not have to return. At the Cardiovascular Center at George Washington University Hospital, the new GW Women's Heart Program opened June 26th. It is very exciting for GWU Hospital, as it is the only center of its kind in the Washington, DC, area, as well as being unique clinic in the U.S. The Women s Heart Program is exclusively dedicated to the preventing, diagnosing, and treating of cardiovascular disease in women. The Clinical Director of the program is Susan K. Bennett, MD. Other Advancements at George Washington University Hospital GWU Hospital has also been performing complex biventricular pacing; in this procedure, we are able to resynchronize the heart by putting in a lead in the left as well as right ventricle, to help treat heart failure. In fact, patients who have had this procedure done often enjoy a dramatic improvement with far less shortness of breath and improved exercise tolerance and endurance. It is very exciting. In addition, GWU Hospital has participated and continues to be involved in multiple clinical trials. The biggest advances in EP will be in curing atrial fibrillation, rather than just using medications or sophisticated pacemakers to suppress them. These options are very helpful, but it would be best if we could cure them altogether. As our technique develops, many more patients will become candidates for these curative, catheter-based procedures.