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A quantitative analysis on the intracardiac electrogram contact during ventricular tachycardia ablation

Abstract:

Cardiac arrhythmias are currently treated with ablation procedures, which are guided by X-ray cameras and intracardiac electrograms (EGM) recordings. Recently, the use of catheters with force sensors have been proposed for improving the contact of the sensing catheter over the heart wall, aiming to guarantee the reliability of electrical measurements. Manufacturers of the equipment used for this type of studies have suggested that the catheter has to take a reading above or equal to 5g. We aimed to determine whether the waveform of the EGM can provide us with some information about the good contact conditions of the catheter on the endocardium, by using the recorded force as a gold standard. We first performed a correlation analysis of EGM morphology in terms of the force threshold, and then we made a multivariable analysis based on the Fisher discriminant. The database to be analyzed came from 11 patients (8 males) with mean age of 64.9 years, where 1161 EGM signals were obtained. The EGM set corresponded to the voltage maps of the left ventricle during sinus rhythm. The correlation coefficient between consecutive EGM beats larger and lower than 0.8 in EGM morphology showed similar ratios of averaged force in those beats with larger force (49% vs 46% for force>5g), 29%o vs 28% for force<5g. Fisher discriminant analysis yielded error probability larger than 0.3 for the best discrimination case. These previous results show that the EGM morphology seems to have limited information about the catheter contact when scrutinized with simple signal processing methods.