SASEAP Proceedings: Part 1

Kam Benfield, PA, Melvin M. Scheinman, MD, Sonia Hart, RN, BSN
Kam Benfield, PA, Melvin M. Scheinman, MD, Sonia Hart, RN, BSN
Advanced EP/Troubleshooting Kam Benfield, PA Asheville Cardiology Associates Asheville, NC "Advanced EP/Troubleshooting" was actually a three-part (and three subject) lecture on: 1) Structure and Function of the Atrioventricular (AV) Node; 2) Catheter Ablation of Atrial Flutter; and 3) Mapping and Catheter Ablation of Ventricular Tachycardia. The Structure and Function of the Atrioventricular (AV) Node part of the talk focused on new information about the anatomy and physiology of the AV node and surrounding tissue. A small amount of time was spent discussing the early investigators of AV nodal activity such as, His, Tawara and Koch and their contributions. The cellular basis for AV nodal function was discussed as well as the "mystery" of conduction delay. The origins of dual pathways and AVNRT were discussed and how slow-pathway ablations are done and why they usually work. Pharmacology was discussed briefly and how certain drugs affect the AV node. The action potentials of different cardiac structures were examined in an effort to explain why the AV node exhibits its peculiar behavior. Catheter Ablation of Atrial Flutter discussed common atrial flutter and catheter position during attempted ablation. The majority of the talk focused on the pitfalls of isthmus ablation and how to confirm bi-directional block with activation mapping combined with coronary sinus and tricuspid valve annulus pacing. Complications, although rare, of flutter ablation were also presented. Mapping and Catheter Ablation of Ventricular Tachycardia mainly discussed the mapping and ablation of ischemic (post MI) VT. Voltage mapping and entrainment was discussed as well as the fact that post-MI ventricular tachycardia can be difficult to ablate because it may involve many circuits, not just one as in common atrial flutter. Techniques to identify isthmi, where "lines of block" can be created to stop the VT, were discussed. Non-ischemic VT was also discussed at the end. (See inset for more information about this presentation.) Challenging Ablations Melvin M. Scheinman, MD University of California, San Francisco San Francisco, CA This section is divided into different supraventricular and ventricular ablations. The most common cause of supraventricular tachycardia (AVT) is AV nodal reentry (AVNRT). The vast majority of these patients are cured with ablative lesions placed along the inferior atrial septum (slow pathway region). We describe a small cohort of patients with AVNRT who cannot be ablated in the typical location, but instead must be ablated either within the coronary sinus or at the mitral annulus. The next most common cause of PSVT are found in patients with accessory pathway mediated tachycardia. In these patients, the accessory pathways are ablated either along the right or left annulus or within the septum. We describe ablation of patients with the permanent form of junctional reentrant tachycardia in which the circuit appears to involve the coronary sinus muscle. Ablation within the coronary sinus severed the connection between ventricle and atrium, while ablation at the coronary sinus was required to ablate the pathway potential. Other pathways in the posteroseptal region appear to involve ventricular muscle connections to the branches of veins draining into the coronary sinus and attachment of a muscle coat from the coronary sinus to both the left and right atrium. Another common form of supraventricular tachycardia is atrial flutter. The most common form of this arrhythmia involves a macroreentrant circuit around the tricuspid annulus. The common form of flutter shows negative flutter waves in leads 2, 3 and F and positive flutter waves in V1. An uncommon variety will use the same flutter circuit, but will rotate in the opposite direction producing the opposite ECG pattern (i.e., positive flutter waves in the inferior leads and negative waves in V1). These flutter circuits can be easily ablated by drawing an ablation line from the tricuspid annulus to the inferior vena cava. Patients may present with patterns that are atypical. These atypical patterns may involve either the right or left atrium. In the right atrium, the tachycardia circuit may be located in proximity to the crista terminalis or through channels through scar tissue. The latter mechanism is most common for patients who had prior atrial surgery. These atypical circuits are often quite challenging and require use of advanced mapping devices to properly locate and ablate the flutter circuit. Similar flutter circuits have been found in the left atrium. This is especially common after attempted catheter ablation of atrial fibrillation (see below). The left atrial flutter circuits have been localized as occurring around the pulmonary veins, around veins and contiguous scars as well as around the mitral annulus and around the septum primum. As with the atypical RA flutter circuits, advanced mapping techniques are usually required. The final frontier for ablation of SVT is found for patients with atrial fibrillation. This arrhythmia remains the most challenging for clinical electrophysiologists. The recent discovery that rapid electrical discharges from the muscular coat investing the pulmonary veins led to the use of an ablative procedure that isolated those pulmonary vein foci by placing ablative lesions around the veins. In addition, others use both the isolation procedure as well as other wide left atrial ablative lines that might connect the LA roof as well as the mitral isthmus (from the inferior pulmonary vein to the mitral annulus) in order to obtain maximal cure for patients with atrial fibrillation. Patients with idiopathic ventricular tachycardia (VT) continue to challenge the clinical electrophysiologist. Idiopathic VT is defined as that occurring in patients without structural cardiac disease. The most common location of this arrhythmia is localized to the right ventricular outflow tract (RVOT), and this arrhythmia can be readily ablated after appropriate mapping. A less common variety has been located to the left ventricular outflow tract or to aortic cusps. Proper ablation of these arrhythmias require precise definition of coronary anatomy so as to avoid placing ablative lesions at the os of the coronary artery. Other idiopathic VTs have been localized to the epicardium and can be ablated either through the coronary venus system (which is epicardial) or via catheters that are placed within the pericardium after needle transpericardial entry. A more common form of idiopathic VT involves the left posterior fascicle and produces a tachycardia with right bundle branch block and superior axis. This is a macroreentrant tachycardia that appears to involve the fascicular system and is usually easily ablated after appropriate mapping. In summary, although ablation was introduced almost 25 years ago, the clinical electrophysiologist is still confronted with exciting and challenging arrhythmias. Our approach to these arrhythmia problems are greatly enhanced by advances in mapping techniques, catheter design and integration of anatomy (i.e., CT scans) with our mapping procedures. Recent & Current Device Trials Sonia Hart, RN, BSN Clinical Research Nurse Coordinator Outpatient Team Leader Mid Carolina Cardiology Division of Research Charlotte, NC Pacer and ICD trials are very pertinent to EP. With results from these studies, new guidelines are established to help prevent sudden cardiac death and other illnesses. This article will discuss six recent and current device trials. EnPulse. The first study to be reviewed is EnPulse. EnPulse was a pre-market study to evaluate the accuracy of the Atrial Capture Management feature and the overall system performance of the EnPulse Pacemaker. We completed this study approximately two years ago. Two hundred patients were enrolled in the study (100 in the US and 100 in Europe). Patients were seen at three-, six-, nine-, and 12-month follow ups. Case Study. RCM is a 64-year-old male patient with a history of inferior MI, aortic valve replacement (AVR), coronary artery bypass grafting and COPD. While in the hospital for his AVR, he developed an AV block with a junctional escape rhythm. The patient s heart rate was in the 60-80 range with a narrow QRS complex. The patient was implanted with an EnPulse device in September 2003, and has done well from a cardiac standpoint since. Patient is now more active and plays golf two to three times a week. The impact this study had on EP is that it introduced a new series of pacemakers that allow EP MDs more choices of devices for their patients. RESPECT. The next study to be reviewed is RESPECT. The purpose of this study is to confirm the AT500/EnRhythm intervention pacing effectiveness data previously seen in the ASPECT clinical study and to gather additional data to understand the effectiveness of the intervention pacing features. The goal of the trial is to demonstrate a reduction in symptomatic AF recurrence with intervention pacing algorithms in patients with a pacing indication and a history of atrial arrhythmias with atrial pacing leads located in the region of Bachman s bundle. Four hundred subjects are to be enrolled in this study at approximately 90 centers. Patients will be followed for 15 months. Enrollment started in this study February 2004. Case Study. MC is a 73-year-old male patient with a history of inferior MI, hypertension, hyperlipidemia, and sinus bradycardia. The patient also had symptomatic, paroxysmal atrial fibrillation. The patient was implanted with an AT500 device in August 2005 and has done well from a cardiac standpoint. The impact this study has had on EP is yet to be determined, since this study is still in progress. SAVEPACe. The next study to be reviewed is SAVEPACe. The purpose of this study is to compare the percentage of ventricular pacing at one-month post implant between subjects in the ON & OFF arms implanted with the Kappa 700, Kappa 900, EnPulse or EnRhythm devices. This study is still in progress. The study is also comparing the time to development of persistent AF between all randomized subjects in the ON & OFF arms. Patients will be randomized to Search AV ON or OFF. A total of 1,100 subjects are to be enrolled at approximately 120 centers. Patients will be followed for a minimum for two years and a maximum of six years. Follow-up visits will occur at one month, six months, and then every six months until the end of the study. Enrollment in this study started in 2003. Case Study. FHB is a 71-year-old female with a history of paroxysmal atrial fibrillation, sick sinus syndrome, hypertension, and first-degree heart block. This patient was implanted with a Kappa 900 in April 2003, and was randomized to the ON arm. Since implant, the patient has done well from a cardiac standpoint and is currently still participating in the trial. She is involved in cardiac rehab and missionary activities with her church. SAVEPACe is currently still enrolling, so the impact on EP is still being determined. PAVE. The next study to be reviewed is PAVE. The purpose of this study is to evaluate treatment options for patients with chronic atrial fibrillation who receive an ablate and pace procedure. Three hundred and sixty one patients were enrolled in this study. Patients had to have chronic AF, be NYHA Class II or III and have had an AV nodal ablation. Patients were randomized to biventricular pacing or right ventricular pacing in a 2:1 ratio. This study closed this year. Case Study. JDH is a 68-year-old female with chronic atrial fibrillation and poorly controlled rates. Prior to enrollment in the study, the patient had been cardioverted several times with no success. Before implant, she could not walk from one room to another in her house without being short of breath. The patient was enrolled into the study on June 4, 2003. She was randomized to the BV Pacing arm. She has done very well since implant. She is now able to walk three miles, and does so regularly. She also joined Weight Watchers, lost 18 lbs., and has kept the weight off for over a year. PAVE impacted EP by showing that an AV nodal ablation and biventricular pacing improves cardiac functional capacity in patients. SCD-HeFT. The next study to be discussed is SCD-HeFT. The purpose of this study is to determine the efficacy of ICDs as a primary prevention for sudden cardiac death. A total of 2,521 patients were enrolled. These patients had Class II or III congestive heart failure (CHF) and an ejection fraction (EF) of ? 35%. The patients were randomized to one of three arms: Conventional therapy + placebo Conventional therapy + amiodarone Conventional therapy + single-chamber ICD Follow-up on these patients lasted two and a half years. Case Study. EP is a 68-year-old male with a history of coronary artery disease, CABG, and ischemic cardiomyopathy. He also has Class III CHF and an EF of 25%. The patient was enrolled in SCD-HeFT in April 1999. He was randomized to the ICD arm of the study. The patient remained stable from a cardiac standpoint until May 2004. He developed intermittent 2:1 AV block and his heart failure symptoms worsened. EP was upgraded to a biventricular ICD in June 2004. He continues to be followed by our clinic and is stable. SCD-HeFT impacted electrophysiology because the results showed that mortality improved in the ICD arm, but there was no difference between amiodarone and placebo. SCD-HeFT confirmed MADIT II conclusions. In addition, SCD-HeFT received CMS approval, so that patients who meet SCD-HeFT criteria can now receive ICDs. COMPANION. The final study to be discussed is COMPANION. The purpose of this study is to study the effect of cardiac resynchronization therapy (CRT) with or without defibrillation on death, as well as hospitalization in heart failure patients when compared to optimal pharmacologic therapy. A total of 1,520 patients were randomized in the study at 128 centers. All patients were required to be on optimal pharmacologic therapy. 20% received OPT alone 40% received OPT & CRT-P 40% received OPT & CRT-D Patients were followed for approximately two and a half to three years. Case Study. SCC is a 75-year-old male with a history of Class III CHF, nonischemic cardiomyopathy, HTN, and left bundle branch block. The patient was randomized to the OPT+CRT-D arm in September 2001. This patient has been followed by our clinic for the past four years, and has had no significant heart failure symptoms. He is now a Class I CHF patient. The patient is able to hunt and does so frequently. COMPANION impacted electrophysiology by showing that CRT-D, in combination with OPT, reduced the risk of all-cause mortality by 36%.