EP Lab Digest - December 2007 - (Page 18)

18 INSIDE THE EP LAB DECEMBER 2007 Emerging Technologies for the Electrophysiology Lab Jeffrey Mendel, MD, Chair, Department of Radiology, Caritas Saint Elizabeth’s Medical Center, Boston, Massachusetts ew technologies are emerging to integrate the 3D volume information obtained with multi-detector computed tomography (MDCT) scanning to the electrophysiology lab. These offer a major improvement in the ability of the electrophysiologist to accurately and safely target and treat atrial fibrillation. Atrial fibrillation is the most common cause of sustained cardiac arrhythmia and a major cause of stroke.1 The pharmacologic treatment of atrial fibrillation has significant iatrogenic morbidity. It is associated with the costs of long-term medical treatment, including lifetime monitoring of clotting factors (INR), hospital admissions for bleeding complications, as well other needed therapy while on long-term anticoagulates. Pioneering work by Haissaguerre and colleagues2,3 has documented that the vast majority of triggering foci for atrial fibrillation occur in the pulmonary veins, and radiofrequency ablation techniques have produced consistently high cure rates. The addition of pre-procedure cross-sectional imaging to identify important anatomic structures offers the opportunity to improve the safety and speed of the ablation procedure. This new concept in electrophysiology (EP) labs combines the latest MDCT and proven EP and cath interventional lab technologies with a number of innovative instruments to help make them more convenient and efficient, thereby creating a more intuitive EP lab working environment and integrating data management across the EP care cycle. N coronary anatomy, MDCT can also be useful in guiding AF ablation by providing a pre-procedural assessment of the pulmonary vein anatomy. First, CT pulmonary venography enables assessment of the left atrium and the location and anatomy of the pulmonary veins, including congenital anatomic variants. Additionally, mass effects from adjacent structures, such as the aorta and esophagus, can be assessed on the CT scan. Second, CT venography can be used for both pre-procedure planning and direct guidance of the procedure. CT data can be transmitted to the electrophysiology lab and used to construct 3D modeling. Finally, CT venography is useful for assessment of both immediate and delayed complications. The protocol for CT pulmonary venography is similar to that used for CT coronary angiography, with a few key changes.The scan can be performed at a lower radiation dose because thicker slices than those used for coronary angiography are typically used to assess the coronary venous anatomy. Further reduction of dose can be achieved by using prospectively-gated axial acquisitions (Step & Shoot Cardiac, Philips Medical Systems, Cleveland, Ohio), which can reduce the scan dose by up to 80% compared to a spiral retrospective scan. In our institution, scanning is performed in a caudocranial direction (cardiac apex to cardiac base) to minimize any artifact from residual contrast in the superior vena cava. To obtain the most reliable contrast enhancement in these patients, who have variable cardiac function, we routinely use bolus tracking and position the trigger point within the left atrium to initiate scanning. As with coronary computed tomography angiogram (coronary CTA), all of our scans are performed with a dual injector, a saline chaser and dose-reduction software, (Cardiac DoseRight, Philips Medical Systems, Cleveland, Ohio) and they are all reconstructed at a standard 75% window in the R-to-R interval. Although there may be more gating artifacts in the patient population than the population on whom coronary CTA is typically performed, these gating artifacts have not been problematic. This is likely due to a combination of the increased slice thickness, which minimizes artifact, as well as beta-blockade, which yields a lower heart rate and less gating artifacts, even with patients who are not in normal sinus rhythm at the time of the examination. is a fifth branch of the pulmonary vein arising from the right middle lobe. Other congenital variants include ostial veins, which are branches off the V1 segment within 5 mm of the ostium, and accessory pulmonary veins, which are additional branches terminating directly into the left atrium. Less commonly, patients present with a common pulmonary trunk on 1 or both sides. In our laboratory, we have also seen 2 cases of partial anomalous pulmonary venous return in the past 3 years. There have also been reports from the literature of absence of the inferior pulmonary vein.4 A variety of structures can indent the posterior wall of the left atrium, including the aorta and esophagus.5 Given the reports in the literature of fistulization6 between the left atrium and esophagus as a result of catheter ablation procedures, we carefully evaluate the location of the esophagus prior to it. Viewing the CT Data Advanced visualization techniques, like the automated whole heart segmentation are now available to augment traditional CT visualization tools, especially in the presence of anatomical variations. Our center offers an identical solution for both the radiology department with EP Planning software on the Extended Brilliance Workspace (Philips Medical Systems, Cleveland, Ohio) and the cardiology suite/EP lab as EP Navigator (Philips Medical Systems, Cleveland, Ohio). Anatomical Variants Performing pre-procedural, non-invasive imaging provides cr itical information to manage mor pholog ical differences. Although most patients have 4 pulmonary veins, the most common variant See TECHNOLOGIES page 20 CT Pulmonary Venography Recent advances in non-invasive imaging modalities like MDCT have facilitated the availability of clinical knowledge earlier in the care cycle, thereby providing opportunities of creating new navigation capabilities and fusion of morphological and physiological information. Primarily a diagnostic modality, CT can also play a vital role in the therapy planning portion of the care cycle. While most of the recent literature using MDCT has focused on the Figure 1. 3D surface (left) and CT venoscopy (right) images of accessory pulmonary vein (arrow). Figure 3. Measurement of the combined ostial openings. Note that the axis of measurement is typically tilted in the sagittal plane. Figure 2. Esophagus indenting posterior wall of left inferior pulmonary vein (arrow).

Table of Contents Feed for the Digital Edition of EP Lab Digest - December 2007

EP Lab Digest - December 2007 Improved Anatomical Orientation During AF Catheter Ablation: Experience from Leipzig Heart Center One EP Lab’s Solution to the Administration of Deep Sedation Contents Letter from the Editor Spotlight Interview: Northeast Georgia Medical Center Emerging Technologies for the Electrophysiology Lab The Western Atrial Fibrillation Symposium About the PRECEDE-HF Trial: Interview with William T. Abraham, MD, FACP, FACC, FAHA Overview on Shire and the Discontinuation of Ethmozine®: After the Heart Rhythm Society Intervenes, the Company Changes its Decision Minimizing the Risk of Infection at Children’s Sibley Heart Center: Interview with Nicole Jarrell, RNC, MSN, and J. Renee Watson, RN, CIC Is There a Link Between Gasoline Vapors and Brugada Syndrome? Interview with Darko Kranjcec, MD and Hugues Abriel, MD, PhD New Feature! Pacemaker/ICD Puzzle Email Discussion Group Events Calendar Industry News and Products

EP Lab Digest - December 2007

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