In a preclinical model, HP-SD ablation (90 W/4 s, T ≤65°C) produced an improved lesion-to-lesion uniformity, linear contiguity, and transmurality at a similar safety profile of conventional ablation.

HP-SD ablation strategy results in improved linear continuity, shorter ablation time, and a safety profile comparable to conventional ablation.

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In STEMI patients undergoing primary PCI, AKI assessed by AKIN criteria is a frequent complication, associated with an increased risk of both short- and long-term mortality.

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Background: Activation mapping of scar-related atrial tachycardias (ATs) can be difficult to interpret because of inaccurate time annotation of complex electrograms and passive diastolic activity. We examined whether integration of a vector map can help to describe patterns of propagation to better explain the mechanism and location of ATs. Methods: The investigational mapping algorithm calculates vectors and applies physiological constraints of electrical excitation in human atrial tissue to determine the arrhythmia source and circuit. Phase I consisted of retrospective evaluation in 35 patients with ATs. Phase II consisted of prospective validation in 20 patients with ATs. Macroreentry was defined as a continuous propagation in a circular path >30 mm; localized reentry was defined as a circular path ≤30 mm; a focal source had a centrifugal spread from a point source. Results: In phase I, standard activation mapping identified 28 of 40 ATs (70%): 25 macroreentry and 3 focal tachycardias. In the remaining 12 ATs, the mechanism and location could not be identified by activation and required entrainment or empirical ablation for termination (radiofrequency time, 17.3±6.6 minutes). In comparison, the investigational algorithm identified 37 of 40 (92.5%) ATs, including 5 macroreentry, 3 localized reentry, and 1 focal AT not identified by standard mapping. It also predicted the successful termination site of all 37 of 40 ATs. In phase II, the investigational algorithm identified 12 macroreentry, 6 localized reentry, and 2 focal tachycardias that all terminated with limited ablation (3.2±1.7 minutes). It identified 3 macroreentry, 3 localized reentry, and 1 focal AT not well characterized by standard mapping. The diagnosis of localized reentry was supported by highly curved vectors, resetting with increasing curve and termination with limited ablation (22±6 s). Conclusions: Activation mapping integrating vectors can help determine the arrhythmia mechanism and identify its critical components. It has particular value for identifying complex macroreentrant circuits and for differentiating a focal source from a localized reentry.

Background: Radiofrequency ablation using irrigated catheters is performed using a power-controlled mode. However, lesion size is dependent on current delivery at a particular impedance, such that a power value alone may not reflect actual energy delivery, resulting in lesion size variability at similar power settings. We hypothesized that modulating baseline impedance at fixed power settings affects ablation lesion dimensions. Methods: In 20 ex vivo swine hearts, radiofrequency ablation was performed using an irrigated catheter at a fixed power setting of 30 W per 20 seconds and a multistepped impedance load (100–210Ω). In 4 in vivo thigh muscle preparations and right atria, ablation was performed using similar power settings at 3 baseline impedances: low (90–130Ω), intermediate (131–180Ω), and high (181–224Ω). The relationship between baseline impedance, current, and lesion dimensions was examined. Results: Baseline impedance had a strong negative correlation with current squared ( I 2 ) for all experimental models: ex vivo (R=−0.94; P <0.0001), thigh muscle (R=−0.93; P <0.0001), and right atria (R=−0.94; P <0.0001). Lesion dimensions at similar power settings were highly variable and directly related to I 2 (width [R=0.853], depth [R=0.814]). In the thigh muscle, lesion depth was 8.2±0.7, 6.5±0.8, and 4.2±0.5 mm for low, intermediate, and high impedance, respectively ( P <0.0001). In right atria lines, low baseline impedance resulted in wider lines (7.2±1.4 mm) relative to intermediate (5.8±1.8 mm) and high impedance (4.7±1.7 mm; P <0.0001). Conclusions: Radiofrequency ablation in a power control mode results in variable lesion dimensions that are partially related to differences in baseline impedance and current output. Ablation at a lower baseline impedance results in increased current output and lesion dimensions.