Heterogeneity of myocardial scar assessed by magnetic resonance imaging in patients with chronic chagasic cardiomyopathy and ventricular tachycardia: a clinical, electro anatomic and imaging correlation

• Grant number: 12/14413-2
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2013
• End date: February 29, 2016
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Angelo Amato Vincenzo de Paola
• Grantee: Angelo Amato Vincenzo de Paola
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated researchers: Lucas Hollanda Oliveira

Abstract

Chagas disease is an illness caused by the protozoan Trypanosoma cruzi, is transmitted to humans through Triatoma, popularly known as "kissing bugs" (especially Triatoma infestans and Rhodnius prolixus3). The mechanism of ventricular tachycardia in Chagas patients living in abnormal electrical impulses associated with the presence of apical aneurysms, conduction disturbances in the upper left anterior fascicle and also microreentrada circuits. Areas of extensive fibrosis associated with areas of inflamed tissue and microvascular ischemia provide the setting conducive to the emergence of reentry. With the destruction of parasympathetic nerve fibers, sympathetic tonus is elevated so as to favor the induction of SVT / VF by modifying the electrophysiological properties of the myocardium.Traditionally, the ablation of ventricular tachycardia is performed by the conventional method, which consists in inducing arrhythmia followed by the "mapping activation." This technique allows identification of the isthmus of the re-enables the success of the procedure in most cases. The concept of ablation substrate is an alternative feasible, especially for individuals who do not tolerate maintenance of clinical tachycardia. Is to be sought during sinus rhythm, slow conduction regions which have the theoretical potential to act as the Isthmus of possible tachycardia (including clinics). The usefulness of the CARTO ® 3 in patients with Chagas disease has been shown by several authors. The use of these devices in patients with ischemic TVS is already well established.This work has a primary goal to evaluate the correlation between areas of fibrosis on CT and MRI identificadasos cardíacasde 3 Tesla with low-voltage areas identified by electroanatomic mapping system CARTO ® 3 (Biosense Webster Inc, Diamond Bar, CA, USA) bipolar and unipolar mode, both the epi and endocardium of chagasic patients undergoing ablation of SVT. For both the targeting system of the left ventricle (LV) in 17 areas will be utilizado35. The channels of myocardial tissue patients, but electrically assets located within the scar and CARTO identified by means of electrophysiological and maneuvers will be correlated with changes equivalent area on the image obtained by MRI 3 Tesla.The reliable identification of areas of fibrosis prior to the procedure of ablation of SVT in chagasic patients can reduce the duration of anesthesia that the patient will be submitted, reduce procedure time, radiation exposure time and intuitively, the risk of complications. Better knowledge of the possible circuits involved in the pathogenesis of TVS also allows the production of specific strategies for each patient. To our knowledge, no studies in literature comparing unipolar and bipolar electrograms obtained during mapping with voltage-identified areas of fibrosis in cardiac MRI. Moreover, comparison of the diagnostic accuracy of cardiac MRI in identifying areas of scarring in relation to voltage mapping by electroanatomic system has not been described in patients with Chagas disease. The importance of determining the minimum mass of fibrosis by MRI can be detected for Carto in chagasic patients also awaits further clarification. IIg et al46 recently. showed the characteristics of the injury caused by radiofrequency application in the ventricle of patients without structural heart disease using the technique of delayed enhancement by MRI. The usefulness of this tool on chagasic patients has not been demonstrated. (AU)