Background-Endocardial mapping before sustained monomorphic ventricular tachycardia (SMVT) induction may reduce mapping time during tachycardia and facilitate the ablation of unmappable VT. Methods and Results-Left ventricular electroanatomic voltage maps obtained during right ventricular apex pacing in 26 patients with chronic myocardial infarction referred for VT ablation were analyzed to identify conducting channels (CCs) inside the scar tissue. A CC was defined by the presence of a corridor of consecutive electrograms differentiated by higher voltage amplitude than the surrounding area. The effect of different levels of voltage scar definition, from 0.5 to 0.1 mV, was analyzed. Twenty-three channels were identified in 20 patients. The majority of CCs were identified when the voltage scar definition was Յ0.2 mV. Electrograms with Ն2 components were recorded more frequently at the inner than at the entrance of CCs (100% versus 75%, PՅ0.01). The activation time of the latest component was longer at the inner than at the entrance of CCs (200Ϯ40 versus 164Ϯ53 ms, PՅ0.001). Pacing from these CCs gave rise to a long-stimulus QRS interval (110Ϯ49 ms). Radiofrequency lesion applied to CCs suppressed the inducibility in 88% of CC-related tachycardias. During a follow-up of 17Ϯ11 months, 23% of the patients experienced a VT recurrence. Conclusions-CCs represent areas of slow conduction that can be identified in 75% of patients with SMVT. A tiered decreasing-voltage definition of the scar is critical for CC identification.

Electrograms with IDCs related to clinical VT can be identified in the majority of patients during RVA pacing. Radiofrequency ablation of E-IDC seems effective in controlling unmappable VT.

Cardiac anatomy is complex and its understanding is essential for the interventional arrhythmologist. The first difficulty is the terminology used to (PACE 2010; 33:497-507) fluoroscopy, ablation, mapping, anatomy, attitudinal nomenclature IntroductionThe establishment of radiofrequency catheter ablation as the mainstay in the treatment of tachycardia in man has renewed the interest in cardiac morphology. The interventional arrhythmologist has drawn attention not only to the gross anatomic details of the heart, but also to some architectural and histological characteristics of various cardiac regions that are relevant to the understanding of the tachycardia substrates, and the potential complications of catheter ablation. Progress in these areas has not ceased. In this review, therefore, the first of a proposed series, we update and expand previous accounts of cardiac anatomy as seen by the arrhythmologist.

Age at the onset of symptoms, sensation of rapid regular pounding in the neck during tachycardia, and female sex are the only significant clinical variables in the differential diagnosis of paroxysmal atrioventricular reciprocating tachycardias in patients without pre-excitation in sinus rhythm. Their consideration adds significant diagnostic information to the ECG.

Introduction. Cardiotoxicity represents a major limitation for the use of anthracyclines or trastuzumab in breast cancer patients. Data from longitudinal studies of diastolic dysfunction (DD) in this group of patients are scarce. The objective of the present study was to assess the incidence, evolution, and predictors of DD in patients with breast cancer treated with anthracyclines.Methods. This analytical, observational cohort study comprised 100 consecutive patients receiving anthracycline-based chemotherapy (CHT) for breast cancer. All patients underwent clinical evaluation, echocardiogram, and measurement of cardiac biomarkers at baseline, end of anthracycline-based CHT, and at 3 months and 9 months after anthracycline-based CHT was completed. Fifteen patients receiving trastuzumab were followed with two additional visits at 6 and 12 months after the last dose of anthracycline-based CHT. A multivariate analysis was performed to find variables related to the development of DD. Fifteen of the 100 patients had baseline DD and were excluded from this analysis.

The two episodes of syncope in strategy A occurred secondary to fast VT unsuccessfully treated by ATP. †Fisher exact test. CI ϭ confidence interval; CL ϭ cycle length; FVT ϭ fast ventricular tachycardia; HES ϭ high-energy shocks; OR ϭ odds ratio.

The presence of pseudo r' deflection and/or pseudo s-wave, an identifiable P-wave after the QRS, and QRS alternans during tachycardia permit us to derive a reliable logistic model to predict the mechanism of paroxysmal AVRT in patients without pre-excitation. Precise probabilities for a correct diagnosis associated with every combination of those classical ECG criteria are presented.

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