When did NASPE get So Big?

Jeff Schoeben, RCVT, EP Coordinator, St. Luke's Regional Medical Center, Boise, Idaho

I walked out of a presentation at this year's 22nd Annual North American Society of Pacing and Electrophysiology's Scientific Sessions, I heard someone say, "when did NASPE get so big?" This made me think, how did we come this far, this fast, and what does the future hold for the field of Electrophysiology?

Ten years ago I remember sitting in front of the E for M watching three electrocardiogram channels and three intracardiac channels. After a four- to six-hour basic EP study, we would or would not have induced ventricular tachycardia. If not, we would fan-fold two to three hundred feet of recording paper. If we did, we still folded paper, but took the patient back to their room and loaded the patient with an anti-arrhythmic drug for three days, then brought him/her back for another study. This would only take two to three hours. If VT was still inducible, the patient was put on another antiarrythmic and brought back to the EP lab three days later. Three drug trials would be the maximum and if all failed; the patient may get a "new" therapy, i.e., the automatic implantable cardiac defibrillator. Another system out at this time was the Gould. It had eight channels and a basket to catch the bi-fold paper. Every morning we would use a 60cc syringe with a piece of rubber tubing to blow out the ink jets, then we would replace the ink cartridge and begin our study.

About this time, the Prucka recording system was released. It had a live screen and a review screen, 12-lead capabilities, multi-programmable channels; information recorded on optical disc and printed snapshot capabilities. From this point, all recording system companies chased Prucka. The competition has been advantageous for the field of Electrophysiology. EP Medical Systems and Bard are two more companies that have excelled. The continual improvements in these systems have decreased our case times with faster computers, more disc storage space and more organized screen layouts.

Diagnostic and radiofrequency catheter advancements have also decreased case times. Most of us in EP labs find a comfort zone with our "work horse" diagnostic catheters, whether they are a quadripolar fixed curve or a steerable multi-pole catheter. However, there are times that these are not the correct tools for the job. This is where catheter companies have done an excellent job. They have listened to the Electrophysiologists and staff to fill our needs. Some examples would be:

• Webster Laboratories have made their ablation catheters bi-directional as well as asymmetric for the most commonly used curves. In addition, they've made available longer reach ablation catheters for those larger hearts, and the Lasso catheter for ease of mapping pulmonary vein ostia. Also, due to the FDA regulations on re-sterilization, Webster has made less expensive diagnostic catheters.
• Even though it was a mistake in packing that gave the design, the CRD-2 by the DAIG Corporation has proven to be helpful in attaining good bundle of HIS tracings. Their 4 French coronary sinus catheter has been helpful when we are unable to place a catheter as deep in the CS as needed for accessory bypass tract identification.
• The "Stinger", by Bard, which has, in my opinion, the best steering control.
• There were other companies I saw, many with radiofrequency catheter prototypes and some in clinical trials that had a larger tip (8–10 mm), were linear in design or were even circular for ablating pulmonary vein ostia.

With continued research in catheter technologies, the safety, efficiency and success of procedures will continually improve.

Increased safety in ablative techniques has occurred in Radiofrequency Generators as well. The original American Cardiac Ablation Corporation Generator allowed us to apply voltage and monitor impedance to cardiac tissue, but gave us no control of temperature. Then, EP Technologies brought the EPT-1000 to EP labs. This allowed us to do more controlled tissue desiccation. During one case, I did a comparison of the two machines and found that 70 volts was too much power to achieve an adequate lesion. When we used the EPT 1000, 60º C was achieved with 10 watts of power. This made me wonder how many times we had created emboli in patients while trying to help them?

On the other hand, I have also done many cases where we had low temperatures at the 50-watt maximum power. Hence the need for more power; the question is, how much more? On the market now are some generators that have a 60-watt maximum. Personally, I do not see this as adequate. I believe we need generators capable of 100-watt maximums.

Until these are FDA-released, the best solution seems to be the Cardiac Pathways saline-cooled Chili^™ catheters and generator. This system has allowed our EP Physicians to create deeper lesions for atrial flutter and ventricular tachycardia ablations. Other options in the future are ultrasound and, as presented at NASPE in an interactive session with Massachusetts General Hospital, cryogenic ablation. The Cryocath Technologies, Inc. catheters and generator were used for an atrio-ventricular node re-entry tachycardia case. The arrhythmia was induced and ablation started using the Cryocath. At -30º C the arrhythmia stopped and, to prove the use of this system, the catheter was re-warmed. The AVNRT restarted as catheter temperature neared body temperature, supporting the technology to reverse our ablation lesion if they cause ill effects. Afterwards, the temperature was dropped to -72º C and a permanent 4–7 mm deep lesion was created. Non-inducibility was the endpoint. Again, this showed me that safety of ablation is increasing. Meanwhile, the trend may be leading away from radiofrequency as a therapy.

Radiofrequency has allowed EP labs nationwide to eliminate Wolff-Parkinson-White syndrome, AVNRT, focal atrial tachycardia and atrial flutter in almost all patients who present with these arrhythmias. Multi-focal atrial tachycardia, inappropriate sinus tachycardia and paroxysmal atrial fibrillation are also being eliminated, but to a lesser extent. The aid of mapping systems appears to be effective in increasing success rates while decreasing case times.

Biosense Webster's Carto System and Endocardial Solutions Non-Contact Mapping System control a majority of this market. Both companies have shown software upgrades that make the systems more user-friendly. This allows EP Labs to further decrease case times in these more complicated procedures. Cardiac Pathways and EP Technologies have mapping systems; however, I do not have enough knowledge about them to comment. All in all, I have found these systems much better than pace mapping.

With all the new equipment and increased technologies, we should be able to eliminate any supraventricular arrhythmias that enter the EP lab, including chronic atrial fibrillation. For those patients with ventricular tachycardia or a bradyarrhythmia, great strides have been made in controlling these while increasing the patient's quality of life. Most patients with monmorphic VT are cured with radiofrequency ablation, whether it comes from the right or left ventricle.

However, there is a concern with patients presenting with polymorphic VT or ventricular fibrillation. For these patients, the advances in internal cardiac defibrillator technologies have been responsible for increased survival as well as a better quality of life. Although I am not sure which advance has been the greatest, my choices would be the Biphasic Shock wave form for defibrillation, and the Endocardial instead of Epicardial systems or the development of smaller capacitors allowing generators to be placed in the shoulder instead of the abdomen. After speaking with a multitude of patients who have had both an abdominal as well as a shoulder generator placement, they have expressed how much happier they are with the shoulder location. We have also reduced the number and size of leads required for these systems. In the near future, we will be able to look at an X-ray of a defibrillator system and not see epicardial patches, subcuticular patches or the Cardiac Pacemaker Incorporated Array. Granted, it is nice to have these things, but in the near future, dual capacitor technology will render these obsolete. Add to this the dual chamber pacing capabilities, and it is easy to see why implant numbers keep increasing.

Along with ICD implants increasing, so are pacemaker implants. Again, it is the technologic advances that have allowed us to help a greater number of patients. Over the past several years we have gone from single chamber pacing capabilities to dual chamber pacing capabilities to dual chamber with rate response. Throw in mode switching, rate enhancements and a variety of physiologic monitoring capabilities and one would think that no person should be incapacitated due to their heart's electrical system aging.

At NASPE, the biggest advancement in pacemaker technology seen was biventricular pacing. This should be FDA-released in December with most of the companies having their systems available soon after. Biventricular pacing should allow us to help congestive heart failure patients by resynchronizing the ventricles and optimizing their cardiac outputs. In turn, NYHA Class III and IV patients will be lowered to Class II and III. By slowing the progression of CHF, it should allow us to learn more about the remodeling of the heart and how we can control it earlier; thus, helping to improve these patients' quality of life. As with any new technology, many questions need to be answered before an accepted implant protocol can be implemented. Many of these questions were asked at the NASPE sessions, which included: 1) who should do the implant; 2) how should we visualize the coronary sinus; 3) do we need to see the whole vasculature or just the origin of the vessels; and 4) do we balloon occlude the CS for better visualization and risk dissecting the coronary sinus?

In this article I have not presented all the new technologies seen at NASPE -- there was new lead extraction devices, new imaging systems, Internet websites for patients and physicians and much more. With all these new technologies, informational resources are needed. Although I cannot explain when NASPE got so big, I can tell you why. NASPE is probably the best resource for pacing and electrophysiology because they are always trying to improve communication between all of us in the field of Electrophysiology. Another resource that I hope grows to this level is EP Lab Digest. This publication gives technologists and nurses a resource to communicate and share our experiences in the EP lab. In turn, the field will continue to grow and benefit patients.

Editor's Note:
by Todd J. Cohen, MD

Previously I had published an article, which announced that Medtronics had won approval by the United States Food and Drug Administration (FDA) panel for its InSync^® heart failure pacemaker. On July 10, 2001, Medtronic, Inc. announced that its InSync cardiac resynchronization device for treating moderate to severe heart failure with left ventricular dyssynchrony was unanimously approved by the circulatory device panel of the FDA. It was based on the multicenter InSync Randomized Clinical Evaluation trial known as the MIRACLE trial, which evaluated the benefits of the device (model #8040). This is a biventricular pacing device, which was shown to improve the patient's quality of life, exercise tolerance, and functional status. At the same time that this device was approved, their competitor, Guidant Inc., failed to gain approval of the Contak CD pacemaker for the treatment of congestive heart failure. The FDA advisory panel voted six to two against recommending approval of the Contak CD based on the failure of this device to meet the endpoint of cutting progression of heart failure by 25% (only a 21% reduction in progression of heart failure was demonstrated).

It appears clear that cardiac resynchronization therapy is in the near future and more closely in the future for the Medtronics device. The fact is that the concept of biventricular pacing/cardiac resynchronization therapy is not a new one and in fact, myself, along with Jack Lattuca and Morton Mower, MD, were involved in the investigation of this type of methodology in an animal model back in the late 1980s. Below is an abstract (Figure 1), published in 1990, from one of the first animal experiences demonstrating the utility of biventricular pacing as resynchronization therapy.

It is my pleasure to include this early work in this new exciting field, though perhaps it is really not as new as most people believe!

Bi-Ventricular Pacing to Improve Cardiac Hemodynamics

J.J. Lattuca, T.J. Cohen, and M.M. Mower, Sinai Hospital, Baltimore, Maryland, and CPI, St. Paul, Minnesota

Incoordinate contraction pattern might be partly responsible for hemodynamic impairment in heart failure. To determine if narrowing the QRS width by simultaneously pacing several sites on the heart would improve hemodynamics, pacing was done on three dogs comparing pacing right and left ventricles alone with both sides simultaneously using a Seamed external pacer device. Artificial AV interval was set shorter than intrinsic, and animals were paced at 150, 175, and 190 BPM. Three replicate measurements were made at each setting. Results (simple means of all measurements) are displayed in the table. 

While increased cardiac output and aortic pressure with narrowed QRS complex indicate improved systolic function, the marked right atrial pressure reduction in even more impressive and suggests a favorable effect on diastolic relaxation as well. The clear implication is that some patients in congestive heart failure with conduction defects could be dramatically helped by reducing elevated right atrial pressure through such means.