ABSTRACT
BACKGROUND: Assessment of origin of ventricular tachycardias (VTs) arising from epicardial vs endocardial sites are largely challenged by the available criteria and etiology of cardiomyopathy. Current electrocardiographic (ECG) criteria based on 12-lead ECG have varying sensitivity and specificity based on site of origin and etiology of cardiomyopathy. OBJECTIVES: This study sought to test the hypothesis that epicardial VT has a slower initial rate of depolarization than endocardial VT. METHODS: We developed a method that takes advantage of the fact that electrical conduction is faster through the cardiac conduction system than the myocardium, and that the conduction system is primarily an endocardial structure. The technique calculated the rate of change in the initial VT depolarization from a signal-averaged 12-lead ECG. We hypothesized that the rate of change of depolarization in endocardial VT would be faster than epicardial. We assessed by applying this technique among 26 patients with VT in nonischemic cardiomyopathy patients. RESULTS: When comparing patients with VTs ablated using epicardial and endocardial approaches, the rate of change of depolarization was found to be significantly slower in epicardial (mean ± SD 6.3 ± 3.1 mV/s vs 11.4 ± 3.7 mV/s; P < 0.05). Statistical significance was found when averaging all 12 ECG leads and the limb leads, but not the precordial leads. Follow up analysis by calculation of a receiver-operating characteristic curve demonstrated that this analysis provides a strong prediction if a VT is epicardial in origin (AUC range 0.72-0.88). Slower rate of change of depolarization had high sensitivity and specificity for prediction of epicardial VT. CONCLUSIONS: This study demonstrates that depolarization rate analysis is a potential technique to predict if a VT is epicardial in nature.
ABSTRACT
Epicardial interventions have forged new frontiers in cardiac ablation and device therapies. Healthy human hearts typically present with significant adipose tissue layers superficial to the ventricular myocardium and may hinder success or increase the complexities of epicardial interventions. We quantitatively evaluated the distribution of epicardial adipose tissue on the surface of human hearts and provided high-fidelity 3-dimensional reconstructions of these epicardial adipose tissue layers. The regional thickness of adipose tissues was analyzed at 51 anatomical reference points surrounding both ventricles and compared to specific patient demographics. Adipose deposits on the human hearts displayed characteristic patterns, with the thickest accumulations along the interventricular septa (anterior, 9.01 ± 0.50 mm; posterior, 6.78 ± 0.50 mm) and the right ventricular margin (7.44 ± 0.57 mm). We provide one of the most complete characterizations of human epicardial adipose location and relative layer thickness. These results are considered fundamental for an underlying anatomic understanding when performing procedures within the pericardial space.
ABSTRACT
BACKGROUND: The DiamondTemp ablation (DTA) system is a novel temperature-controlled irrigated radiofrequency (RF) ablation system that accurately measures tip-tissue temperatures for real-time power modulation. Lesion morphologies from longer RF durations with the DTA system have not been previously described. We sought to evaluate lesion characteristics of the DTA system when varying the application durations. METHODS: A bench model using porcine myocardium was used to deliver discrete lesions in a simulated clinical environment. The DTA system was power-limited at 50 W with temperature set-points of 50 °C and 60 °C (denoted Group_50 and Group_60). Application durations were randomized with a range of 5-120 s. RESULTS: In total, 280 applications were performed. Steam pops were observed in five applications: two applications at 90 s and three applications at 120 s. Lesion size (depth and maximum width) increased significantly with longer applications, until 60 s for both Group_50 and Group_60 (depth: 4.5 ± 1.2 mm and 5.6 ± 1.3 mm; maximum width: 9.3 ± 2.7mm and 11.2 ± 1.7mm, respectively). As lesions transition from resistive to conductive heating (longer than 10 s), the maximum width progressed in a sub-surface propagation. Using a "Time after Temperature 60 °C" (TaT60) analysis, depths of 2-3 mm occur in 0-5 s and depths plateau at 4.6 ± 0.8 mm between 20 and 30 s. CONCLUSIONS: The DTA system rapidly creates wide lesions with lesion depth increasing over time with application durations up to 60 s. Using a TaT60 approach is a promising ablation guidance that would benefit from further investigation.
