Assessment of atrial fibrillation inducibility based on epicardial mapping signals / 生物医学工程学杂志

Atrial fibrillation (AF) is the most common arrhythmia in clinic, which can cause hemodynamic changes, heart failure and stroke, and seriously affect human life and health. As a self-promoting disease, the treatment of AF can become more and more difficult with the deterioration of the disease, and the early prediction and intervention of AF is the key to curbing the deterioration of the disease. Based on this, in this study, by controlling the dose of acetylcholine, we changed the AF vulnerability of five mongrel dogs and tried to assess it by analyzing the electrophysiology of atrial epicardium under different states of sinus rhythm. Here, indices from four aspects were proposed to study the atrial activation rule. They are the variability of atrial activation rhythm, the change of the earliest atrial activation, the change of atrial activation delay and the left-right atrial dyssynchrony. By using binary logistic regression analysis, multiple indices above were transformed into the AF inducibility, which were used to classify the signals during sinus rhythm. The sensitivity, specificity and accuracy of classification reached 85.7%, 95.8% and 91.7%, respectively. As the experimental results show, the proposed method has the ability to assess the AF vulnerability of atrium, which is of great clinical significance for the early prediction and intervention of AF.

Epicardial Ablation of Ventricular Tachycardia: a Review

For over 3 decades, it has been known that reentry circuits for ventricular tachycardia (VT) are not limited to the subendocardial myocardium. Rather, intramural or subepicardial substrates may also give rise to VT, particularly in those with non-ischemic cardiomyopathy. Percutaneous epicardial mapping and ablation has been successfully introduced for the treatment of such subepicardial VT. Herein, we review the indications for epicardial ablation and the identification of epicardial VT by electrocardiographic and imaging modalities. We also discuss the optimal technique for epicardial access and the implications of epicardial fat which has the potential to mimic scar, decreasing the specificity of electrogram morphology and impeding energy delivery to the tissue. Finally, we also report on possible complications of the procedure and strategies to mitigate adverse events.

Catheter Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is predominantly an inherited cardiomyopathy with typical histopathological characteristics of fibro-fatty infiltration mainly involving the right ventricular (RV) inflow tract, RV outflow tract, and RV apex in the majority of patients. The above pathologic evolution frequently brings patients with ARVD/C to medical attention owing to the manifestation of syncope, sudden cardiac death (SCD), ventricular arrhythmogenesis, or heart failure. To prevent future or recurrent SCD, an implantable cardiac defibrillator (ICD) is highly desirable in patients with ARVD/C who had experienced unexplained syncope, hemodynamically intolerable ventricular tachycardia (VT), ventricular fibrillation, and/or aborted SCD. Notably, the management of frequent ventricular tachyarrhythmias in ARVD/C is challenging, and the use of antiarrhythmic drugs could be unsatisfactory or limited by the unfavorable side effects. Therefore, radiofrequency catheter ablation (RFCA) has been implemented to treat the drug-refractory VT in ARVD/C for decades. However, the initial understanding of the link between fibro-fatty pathogenesis and ventricular arrhythmogenesis in ARVD/C is scarce, the efficacy and prognosis of endocardial RFCA alone were limited and disappointing. The electrophysiologists had broken through this frontier after better illustration of epicardial substrates and broadly application of epicardial approaches in ARVD/C. In recent works of literature, the application of epicardial ablation also successfully results in higher procedural success and decreases VT recurrences in patients with ARVD/C who are refractory to the endocardial approach during long-term follow-up. In this article, we review the important evolution on the delineation of arrhythmogenic substrates, ablation strategies, and ablation outcome of VT in patients with ARVD/C.

A Method for Pretreatment and Character Extraction of Epicardial Signals Based on Template Matching / 航天医学与医学工程

Objective To explore a method for real-time pretreatment and character extraction of epicardial signals and promote the research on the electrophysiological mechanism of atrial fibrillation (AF).Methods Firstly,an analysis was made to get the properties of epicardial signals. Then,a method based on template matching was used to extract atrial activities from epicardial signals. At last,the feature points of atrial activities could be recognized.Results The correctness of recognizing feature points of sinus rhythm and AF were 99.7% and 97.0% respectively. Furthermore,only 1~2 s were cost to compute a 10-second data record with this method.Conclusion The proposed method can extract crucial information about atrium depolarization from epicardial signals and is adequate for online analysis.

Correlation Analysis of Epicardial Depolarization Wave Based on Combined Unipolar and Bipolar Mapping Technique / 航天医学与医学工程

Objective To find a method for real-time measurement of epicardial electrical activity suitable for clinical application.Method Combined unipolar and bipolar mapping technique for recording epicardial electrical activity was applied to detect the propagation of depolarization wave over the epicardium.Epicardial signals from 4 pigs were sampled simultaneously during sinus rhythm or atrial fibrillation(AF).Result Active isopotential map showing the spread of excitation on epicardial surface was demonstrated and correlation analysis data were obtained.The difference in correlation coefficients between adjacent sites was evident during sinus rhythm(above 0.8) and AF(about(0.5).) Conclusion The result shows that combined unipolar and bipolar technique improves the electrode efficiency and the precision in epicardial mapping.Distribution of depolarization wave or the reentry pathway during complex arrhythmia may be revealed by correlation analysis.

Experimental Study on Ventricular Fusion in Wolff-Parkinson-White Syndrome

WPW syndrome is the most common variaty of preexcitaton syndrome in which whole or part of ventricular muscle is activated by the atrial impulse earlier than would be expected if the impulse reached the ventricle by way of normal conduction system alone. WPW syndrome result from existence of accessory muscle bridge(atrio ventricular connection) between atrium and ventricle. The ventricular complex observed in WPW syndrome during periods of sinus rhythm is the result of fusion, with intial phase of ventricular activation representing excitation via accessory pathway and later forces produced by excitation of residual portions of ventricle via normal His-purkinje system. The variations in QRS aberrancy in WPW syndrome depend on varying degree of preexcitation. This experimental study was undertaken to increase our knowledge on the ventricular fusion in WPW syndrome through epicardial mapping after experimental induction of ventricular preexcitaion of WPW type. In 5 normal dogs, the heart was widely exposed through transverse thoracotomy and positioned in a pericardial cradle, then electric wires were fixed on the epicardium of right atrium and ventricular bases(anterobasal and posterobasal) areas of right ventricle, anterobasal and poaterobasal areas of left ventricle for atrial and ventricular pacing. Epicardial mapping was then performed during atrial pacing alone and during atrioventricular sequential pacing at the same rate. Atrioventricular sequential pacing was done with various short AV intervals(60-110 msec) for the purpose of premature stimulation on ventricular base. In mapping we used the grid system which consisted of 29 areas to cover the right ventricle and 23 areas to cover the left ventricle. We drew 9 epicardial ishochrone maps in 5 dogs. The epicardial data during atrio-ventriclar sequential pacing were then compared with those during atrial pacing at an identical rate to study the ventricular fusion in WPW syndrome. The results were as follows; 1) The preexciting wave spread radially from the stimulated basal area to the right and left(or anterior and posterior wall) and the apex. 2) Preexciting wavefronts collided with the normal wavefronts in a wide range of ventricular activation time. 3) Preexcitation widened according to the degree of the shortening of the AV interval. 4) The duration of ventricular activation was greater in preexcited ventricles than in normally activated ventricles. The more prematurely the ventricle was stimulated, the greater the duration of ventricular activation was.