Abstract 15612: Force, Power, and Temperature Settings in Slow Pathway Modification Utilizing an Irrigated Force Sensing Ablation Catheter

Introduction: Atrioventricular node reentry tachycardia (AVNRT) ablation is typically performed with solid tip catheters set to temperature control (TC) mode. Radiofrequency (RF) output, tip temperature (T), and junctional rhythm response (JRR) during RF application have been well defined. JRR in an intermittent burst, sinus-junction-junction, or sinus-junction-sinus pattern is associated with successful modification of the AV nodal slow pathway (SP). Irrigated force-sensing catheters (IFSC) are often utilized for mapping and ablation of the SP. Despite this, parameters for IFSC used in TC mode resulting in JRR have not been well described. Hypothesis: Parameters predicting JRR and successful SP modification with IFSC include power (P), force (F), impedance drop (I), and target temperature (T). Methods: Consecutive patients that underwent electrophysiologic study and successful ablation of typical AVNRT with an IFSC were studied. Lesion parameters including P, T, F, time and I change were analyzed. Lesions producing JRR were considered efficacious. Independent T-Test and ANOVA were used to determine significance between the two groups (efficacious and non-efficacious lesions). Results: 296 lesions in 39 patients (age 52+/-14) were analyzed. All patients had successful SP modification without complication. Average F producing JRR was 8g, average T producing JRR was 41 o C, average I drop producing JRR was 9 Ohms, and average P producing JRR was 28W. Only RF lesion time was a significant predictor of JRR (p=0.009). (Table 1). Conclusions: Successful SP modification with IFSC was accomplished with catheter contact force as low as 2g. Lower average tip T, and lower average P settings compared to parameters typically used with solid tip catheters were observed. Parameters including P, F, T, and I change were not predictive of JRR. Additional studies controlling for catheter location while varying parameters are indicated.

Differentiating Atrioventricular Reentry Tachycardia and Atrioventricular Node Reentry Tachycardia Using Premature His Bundle Complexes

Background: Current maneuvers for differentiation of atrioventricular node reentry tachycardia (AVNRT) and atrioventricular reentry tachycardia (AVRT) lack sensitivity and specificity for AVRT circuits located away from the site of pacing. We hypothesized that a premature His complex (PHC) will always perturb AVRT because the His bundle is obligatory to the circuit. Further, AVNRT could not be perturbed by a late PHC (≤20 ms ahead of the His) due to the retrograde His conduction time. Earlier PHCs can advance the AVNRT circuit but only by a quantity less than the prematurity of the PHC. Methods: High-output pacing at the distal His location delivered PHCs. AVRT was predicted when late PHCs perturbed tachycardia or when earlier PHCs led to atrial advancement by an amount equal or greater than the degree of PHC prematurity. Results: Among the 73 supraventricular tachycardias, the test accurately predicted AVRT (n=29) and AVNRT (n=44) in all cases. Late PHC advanced the circuit in all 29 AVRTs and none of the AVNRTs (sensitivity and specificity, 100%). With earlier PHCs, the degree of atrial advancement was equal or greater than the PHC prematurity in 26/29 AVRTs and none of the AVNRTs (90% sensitivity and 100% specificity). The mean prematurity of the PHC required to perturb AVNRT was 48 ms (range, 28–70 ms) and the advancement less than the prematurity of the PHC (mean, 32 ms; range, 18–54 ms). Conclusions: The responses to PHCs distinguished AVRT and AVNRT with 100% specificity and sensitivity.