EP Lab Digest - March 2008 - (Page 8)

8 COVER STORY MARCH 2008 ECG 101: THE CASE OF A DIZZY PATIENT WITH A LEFT BUNDLE BRANCH BLOCK Continued from page 6 However, this patient did not meet any criteria for an ICD as he had no demonstrable heart failure, he had a left ventricular ejection fraction exceeding 35%, there was no history of longstanding ventricular dysfunction, and he was not otherwise medically treated for the structural heart disease. We proceeded with a complete electrophysiology study. During that study, spontaneously but more reproducibly with atrial pacing and isoproterenol, the following phenomenon was noted (Figure 1). No other abnormalities were seen. The patient had AV Wenckebach block below the AV node. The block was below the initial part of the His bundle. Intra-Hisian Wenckebach periodicity was seen with further progressive delay in conduction below the distal common His or right bundle. The electrophysiology study (Figure 1) showed normal sinus rhythm. The first and second beats were associated with split His potentials indicating intraHisian disease. Therefore, the conduction disease is not only within the His bundle, but below it as well. Wenckebach periodicity can occur below the AV node and is more likely when conduction system disease is present in the His Purkinje system, as was the case in our patient. Such patients often present with a history of exerciserelated symptoms because heart block increases with increasing sinus rate when catecholamine levels are higher and AV conduction via the AV node is facilitated. More rapid bombardment of the His-Purkinje system leads to greater block due to conduction system abnormalities and increases the refractory period of the His Purkinje system. This is in contradistinction to AV Wenckebach in the AV node. It is important to note that a complete electrophysiology study was performed. There were no supraventricular or ventricular tachycardias induced. In patients like this with non-ischemic cardiomyopathy and His Purkinje disease, a complete electrophysiology study must still be performed since inducible tachyarrhythmias, such as bundle branch reentry tachycardia and other tachycardias, may be the cause of symptoms. This patient’s cardiomyopathy was treated with a beta-blocker and an ACE inhibitor. He was counseled to stop smoking and stop drinking. In addition, his truncal obesity was a concern to us, as this also increases his risk of death. He was also educated about the risks of obesity on coronary artery disease and heart failure. He was scheduled to meet with a dietician to start a weight loss program, but instead agreed to begin a “fad” diet instead. Due to his symptoms and the Wenckebach block in the His Purkinje system, a permanent dual chamber pacemaker was placed. We were not compelled to collect more information from an endless loop recorder or an implantable loop recorder to document spontaneous episodes, as this would not have altered our management plan. He did not meet criteria for an ICD, and certainly did not meet criteria at this point for a CRT device. This case demonstrates several conundrums associated with evaluating patients presenting with dizziness. Following a structured and well thought-out plan while eliminating the possibilities at each step will help the clinician arrive at the most likely Figure 1. Intra-Hisian Wenckebach. The first and second beats are associated with split His potentials, and there is 2:1 AV block noted in the second beat. Also, there is evidence of Wenckebach periodicity. Following a structured and well thought-out plan while eliminating the possibilities at each step will help the clinician arrive at the most likely diagnosis. diagnosis. In follow-up, his ejection fraction improved and he denied any further symptoms. He maintains an active lifestyle and continues to work as a brick layer to support his family. He also recently became the proud father of a baby girl. In the Next Installment: In the next installment of the ECG 101 section, Dr. Abraham Kocheril will provide an extensive overview on Holter monitors, event monitors, and implantable loop recorders. This article is scheduled to appear in our May 2008 issue, so stay tuned! In addition, if you have an article idea for this section, let us know! Please email the editor at “jelrod@hmpcommunications.com”. We look forward to hearing from you!

Table of Contents Feed for the Digital Edition of EP Lab Digest - March 2008

EP Lab Digest - March 2008 ECG 101: The Case of a Dizzy Patient with a Left Bundle Branch Block Delayed Defibrillation: Research and Results Interview with Paul S. Chan, MD Contents Letter from the Editor Spotlight Interview: St. Joseph’s Hospital Health Center Parent Heart Watch from 36,000 Feet… Perspectives from the Annual Leadership Conference Clinical Trial Overview: 2008 Are MRI-Safe Pacemakers and Leads on the Horizon? Q & A with J. Rod Gimbel, MD Navigating Tortuous Coronary Sinus Anatomy Using a Bipolar Lead Email Discussion Group: March 2008 Guidelines on ECG Interpretation Spotlight Interview Update: What Have We Learned? The Value of Educating Staff Events Calendar Industry News and Products Classifieds Advertisers Index In Memoriam

EP Lab Digest - March 2008

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