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Noncontact mapping using the Endocardial Solutions EnSite 3000 system in flutter ablation at patients with right aneurismal atrium NONCONTACT MAPPING USING THE ENDOCARDIAL SOLUTIONS ENSITE 3000 SYSTEM IN FLUTTER ABLATION AT PATIENTS WITH RIGHT ANEURISMAL ATRIUM O. Nutu¹, L.Chiriac², G.Cristian², I.Tintoiu², M.Gheorghe³ ¹Hopital Foch Paris, ²Army’s Clinical Center for Cardiovascular Disease, ³University Titu Maiorescu Bucharest Abstract – The aim of the Study was to identify clinical electrocardiographic and echocardiographic characteristics of atrial flutter radiofrequency ablation at patients with aneurismal dilated atrium using noncontact mapping. Results show that the majority of radio frequency applications in patients with aneurismal dilated atrium was situated in cava tricuspid isthmus, near inferior vena cava evidentiating that noncontact mapping is a safe method in dilated cava tricuspid isthmus Key words – Atrial flutter, radiofrequency Catheter ablation, noncontact mapping, EnSite 3000 System noncontact mapping.The non-contact mapping system consists of a catheter and a powerful computer. The non-contact catheter, which has many sensing electrodes, is put in a stationary location — often in the center of the heart chamber. The catheter acts like a miniature radio antenna, receiving signals from all around the heart chamber and relaying them to the computer. The computer processes the signals and displays the recorded information on a threedimensional map of the heart chamber. ith the noncontact mapping system your we create a computerized model of the heart and record its electrical activation. This three-dimensional model shows your the source of arrhythmia and guides a therapeutic catheter to the arrhythmia source¹. Methods Introduction Arrhythmias affect millions of people worldwide and can result in heartbeats that are either too slow, erratic, or too fast. These arrhythmias cause the blood to pump inefficiently, resulting in dizziness, fatigue, or other symptoms. Fast heartbeats cause the blood to pump inefficiently. There are two types of fast heartbeats: focal arrhythmias and reentrant arrhythmias. In focal arrhythmia (such as focal tachycardia), a site other than the SA node is initiating rhythms, which may cause the heart to beat faster. In reentrant arrhythmias (such as atrial flutter), the electrical signals circulate repetitively in a closed circuit. EnSite 3000 System is a diagnostic tool to help physicians analyze electrical signals in the heart and facilitate catheter placement for therapeutic ablation. Typical atrial flutter in 15 patients, with aneurismal dilated atrium was mapping and treated by ablation in Electrophysiology Laboratory from Army’s Clinic Emergency Center for Cardiovascular Disease. The aim of this study was to identify clinical, electrocardiographic and echocardiographic characteristics of atrial flutter underwent catheter ablation, to report the localization of the ablation line in patients with aneurismal dilated atrium using The study included 15 consecutive symptomatic patients (age 61 ± 13 years; 1 woman) with common counterclockwise atrial flutter were refereed for catheter ablation of the inferior vena cava – tricuspid isthmus. Some degree of sedation was used in apprehensive patients. Antiarrhythmic drugs was usually stopped prior these studies. In selected cases, other cardioactive drugs was administrated for nonarrhythmic cardiovascular problems such as hypertension, angina, and heart failure. The typical electrode catheters used was multipolar (sizes varying from 4 to 8 F). Catheters was inserted via femoral veins. After using local anesthesia, a guide wire is inserted percutaneously through a needle, and a sheath is advanced over the guide wire, then guided fluoroscopically through the sheath to the right atrial atrium.. Heparinization was administrated - 1000 units per hour to keep ACT (Activated clothing time) at 300s. Mapping was performed using only noncontactmapping catheterThe EnSite catheter uses a balloon design with a 64-electrode array arranged over the outside of the balloon. This balloon is positioned in the center of the chamber and does not come in contact with the walls of the chamber being The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34 55 Noncontact mapping using the Endocardial Solutions EnSite 3000 system in flutter ablation at patients with right aneurismal atrium mapped. Using data from the 64-electrode array catheter, the computer uses sophisticated algorithms to compute an inverse solution to determine the activation sequence on the endocardial surface. Data from all points in the chamber are acquired simultaneously. To create a map, the balloon catheter (has current 9.5-F lumen).was positioned in the lower third of the right atrial atrium with the center of the ballon above the level of the coronary sinus ostium and deployed. A conventional (7F standard catheter with a 4 mm tip) deflectable catheter was also positioned in the chamber and used to collect geometry information. A 5-kHz signal was emitted from the tip electrode of the conventional catheter, and the computer analyzes this signal to determine the position of the roving catheter relative to the position of the balloon. The roving catheter is moved throughout the chamber, and the location information is collected by the system². Using this information, the computer creates a model, called a convex hull, of the chamber during dastole. (Fig.1) Fig.1 Three dimensional map of the dilated right atrium using noncontact mapping Once the electrode catheters are placed appropriately, the connections are made via a junction box and isolation units to prevent excess current in the event of random electrical surges. All of the electrograms are displayed simultaneously on a multi-channel oscilloscopic recorder. In addition to the intracardiac signals, several unfiltered surface electrocardiographic leads (i.e., X, Y, and Z or leads I, II, or aVF and V1) are recorded. To reduce the noise generated with the low-frequency signals, the usual filtering frequency for intracardiac signals is between 30 and 40 Hz for the high-pass and 500 Hz for the low-pass filters. Although appropriately placed electrode catheters will record desired signals at any filtering frequency, filter settings between 30 to 40 and 500 Hz are best suited for sharp intracardiac signals such as those from the His bundle and accessorypathways . Undesirable lowfrequency signals can be reduced by a high-pass filter setting of more than 50 to 100 Hz. On the other hand, 60-cycle interference can be eliminated with a low-pass filter setting at 50 Hz. Alteration in the high-bandpass filter for surface electrocardiography can markedly alter the scalar electrocardiographic morphology. Amplification is frequently necessary to identify desirable signals from the specialized conduction system. This can lead to superimposition of the larger myocardial signals on various 56 electrocardiographic tracings. In most recording equipment, however, limiting filters allow the adjustment of amplitude limits.The intracardiac electrocardiographic tracings was timing of electric circuit and determine the direction of impulse propagation. To acquire true local electrical activity, a bipolar electrogram with an interelectrode distance of less than 1 cm is desirable. When unipolar electrograms are obtained, a rapid intrinsic deflection will identify a point of local activation. The data acquisition process was performed automatically by the system, and all data for the entire chamber are acquired simultaneously. A three dimensional map of the right atrium was created. Major landmarks were recorded and labeled on the EnSite map. The area of interest was identified using the three dimensional isopotential map in combination with surface ECG and computed electrograms (coronary sinus, superior vena cava, inferior vena cava and tricuspide valve anullus) Noncontact mapping with the EnSite 3000 System allows single-beat mapping (Fig.2). The inversesolution computations are performed by the system in real time and projected on to the surface of the convex-hull model, creating a 3D model showing the activation sequence within the chamber. Following this, the segment must be analyzed by the operator to find the early activation or vulnerable The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34 Noncontact mapping using the Endocardial Solutions EnSite 3000 system in flutter ablation at patients with right aneurismal atrium region of the reentry circuit. The locator technology that was used to collect the geometry information for the convex hull can then be used to guide an ablation catheter to the proper location in the heart. Because data from the entire chamber are collected simultaneously with the EnSite 3000 system, it can be used to map patients that was hemodynamically stable³. Fig. 2 Noncontact mapping with the EnSite 3000 System allows single-beat mapping Measurements of right atrium were obtained using the two-dimensional echocardiography and EnSite 3000 noncontact mapping system when a detailed geometry of the chamber was reconstructed. The right atrial long axis was measured from the junction of the tricuspid valve and the intraventricular septum to the roof of the right atrium. The right atrial short axis was measured as the maximum distance between the inner borders of the interatrial septum and the free wall of the right atrium. The septal isthmus length was measured as the distance between the junction of the tricuspid septal leaflet with the intraventricular septum and the coronary sinus ostium. The inferior vena cava – tricuspid isthmus length was measured as the distance from the lateral border of the tricuspid annulus to the inferior vena cava origin. Data are expressed as mean ± SD. A probability value of p<0,05, was accepted as statistically significant. Several variables including anatomical atrial data, were tested: age, gender, the type of atrial flutter (chronic vs. paroxysmal), structural heart disease, left ventricular ejection fraction (%), cavatricuspid isthmus dimension (mm), septal isthmus dimension (mm), right atrial size (mm), number of radiofrequency applications (± SD), mitral regurgitation (II, III or IV grade), flutter cycle length (ms), A-wave velocity (cm/s), E-wave velocity (cm/s), E/A, right atrial area (cm²). After geometry was obtained, a short segment of atrial flutter was recorded. The majority of patients were presented in the lab in atrial flutter so induction of the arrhythmia was not necessary. The endocardial activation map demonstrated a counterclockwise istmus dependent flutter. Using the EnGuide location signal, the ablation catheter was guided to the isthmus region. Continuos lesions were created using ablation catheter. (Fig.3). The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34 57 Noncontact mapping using the Endocardial Solutions EnSite 3000 system in flutter ablation at patients with right aneurismal atrium Fig.3. Radiofrequency ablation lesions delivered at the “gap” site in a dilated cavo-tricuspid isthmus , near inferior vena cava septum near coronary sinus. Results The mean number of radiofrequency application Successful isthmus ablation with bi-directional was 17 ± 9 (range from 6 to 33), septal isthmus 27 ± conduction block eliminating right atrial flutter was 4 mm and cava –tricuspid isthmus 45 ± 9 mm. All achieved in all patients. To confirm the absence of patients with remained free of atrial flutter with an conduction across the isthmus following ablation, average follow-up for 6,4 months. Mean total atrial pacing was done from the proximal coronary fluoroscopy time was 39 min. Of the patients with sinus (CS). No conduction was observed across the dilated atrium, undergoing ablation of common delayed conduction. Next, to confirm bi-directional counterclockwise atrial flutter, early atrial block across the isthmus, pacing was performed in fibrillation wasdocumented in 1 patient, presented the lower lateral part of the right atrium showing arrhythmogenic gaps that was corrected afterwards. very delayed activation in the lower interatrial Table 1. Clinical, electrocardiographic and echocardiographic characteristics Atrial flutter (n=15) Age y ± SD 61 ± 13 Type of atrial flutter (chronic vs. paroxysmal) (%) 80 Structural heart disease (%) 100 Radiofrequency applications (%) 17 ± 9 Right atrial size (mm) 61 ± 8 Right atrial area (cm²) 34 ± 8 Septal isthmus dimension (mm) 26 ± 8 Cava-tricuspid isthmus dimension (mm) 44 ± 9 A-wave velocity (cm/s) 0,53 ± 0,16 E-wave velocity (cm/s) 0,8 ± 2 E/A 1,8 ± 0,9 Left ventricular ejection fraction (%) 44,2 ± 13 Mitral regurgitation (%) 60 Atrial flutter cycle length (ms) 270 ± 40 Preablation history of atrial fibrillation (%) 80 Fluoroscopy time (min) 39 ± 12 Conclusions The majority of sequentional radiofrequency applications in patients with aneurismal dilataed atrium was situated in cava tricuspid isthmus, in low region near inferior vena cava. Noncontact mapping has been shown to be an safe method for demonstrating the complete circuit of typical atrial flutter, in dilated cavotricuspid isthmus. The EnSite 3000 system provides a clear, accurate view of chamber anatomy and activation. The clinician can view and analyse aarrhythmia conductionnand precisely label anatomic and ablation sites. Confirmation of therapy is simplified with the dynamic isopotential maps and computed electrograms. These mapping systems, both of which are relatively new, provide electrophysiologists with new tools for diagnosing and treating what are often complex arrhythmias. They make use of state-ofthe-art technology to accomplish their objectives and improve the state of the art in arrhythmia management. Because these technologies are so 58 new, further enhancements can be expected that will further the usefulness of advanced mapping techniques in the practice of electrophysiology. Bibliography 1. 2. 3. 4. Chad E. and colab. - Radiofrequency Catheter Ablation Using Non-Contact Mapping for Inappropriate Sinus Tachycardia - Journal of Interventional Cardiac Electrophysiology, Volume 10, Number 2 / April, 2004, Thomas Pauland colab. - Non-contact mapping and ablation of tachycardia originating in the right ventricular outflow tract - Cardiology in the Young 2002, 12 : 294-297, Reginald Liew and colab.- Use of non-contact mapping in the treatment of right atrial tachycardias in patients with and without congenital heart disease - Europace 2008 10(8):972-981; HurstTechniques of Intracardiac Electrophysiologic Studies – The Heart , 12e 2008. The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34