Contact force during VT ablation: vector orientation is key.

Our understanding of ventricular tachycardia (VT) substrate and mapping has evolved considerably over the past 3 decades. Nonetheless, the outcomes of catheter ablation of scar-mediated VT continue to remain far from perfect.1 There is no doubt that new advances in VT mapping may help improve the outcomes of catheter ablation. But ultimately it will be the quality of the ablation lesions delivered to the VT substrate that will determine the clinical outcomes. This is important because radiofrequency, the principal source of energy used in VT ablation has been presumed to be a suboptimal energy modality for catheter ablation of scar tissue. A recent study found that in experienced hands using the standard 3.5-mm tip irrigated ablation catheter, elimination of late potentials occurred during only one-third of the radiofrequency applications and electrogram reduction with impedance drop >10 Ω in just half of the radiofrequency lesions during VT ablation.2 Yet, experimental data suggest that presence of scar by itself does not significantly impact lesion size or intramural temperatures when stable ablation catheter-tissue contact is maintained during radiofrequency energy delivery through a needle electrode.3 As such, there seems to be a paradox—scar by itself does not significantly affect radiofrequency lesion size or intramural temperature during ablation, however, the efficacy of ablating scar tissue seems poorer than anticipated! Because tissue contact by way of a needle electrode seems most optimal, one may simply ask whether lack of a stable catheter-tissue contact could provide a plausible explanation for our disappointing clinical outcomes. Article see p 1168 Although no concrete data are presently available to support a direct relationship between contact force (CF) and successful elimination of abnormal ventricular electrograms or VT recurrence after catheter ablation, it is conceivable that poor or unstable contact between the ablation catheter tip and myocardial tissue could …