Maximum Deflection Index Research Articles

Electrocardiographic Characteristics of the Epicardial Ventricular Tachycardia in Dilated Cardiomyopathy

Background: Although epicardial ventricular tachycardia (VT) ablation in patients with dilated cardiomyopathy (DCM) is increasingly performed, there may have a potential risk of complications related to epicardial access. The aim of study was to ascertain the electrocardiographic characteristics of epicardial VT related with DCM by using some previously reported electrocardiographic indexes. Methods: Endocardial or epicardial radiofrequency catheter ablation (RFCA) were performed in 16 consecutive DCM patients (3 female; age 56±11 years). In this study, we analyzed the surface electrocardiograms of 15 clinical VTs in 12 patients who were successfully ablated from the epicardial sites. We measured the intervals of ventricular activation: (1) the pseudodelta wave, (2) the intrinsicoid deflection time in V2 (IDT), (3) the shortest RS complex, and (4) the maximum deflection index (MDI), which indexes were previously reported by other papers. Results: A pseudodelta wave of >34 ms had a sensitivity of 100%, an IDT in V2 of >85 ms had a sensitivity of 86%, an RS complex duration of >121 ms had a sensitivity of 73%, and a MDI of >0.55 had a sensitivity of 73% in identifying an epicardial origin of the VTs. Conclusion: Morphological ECG features that described the above-mentioned indexes can help to identify the epicardial origin of DCM-VTs. Especially, a pseudodelta wave of >34 ms in precordial lead is the most useful index of epicardial VT.

Idiopathic Left Ventricular Arrhythmias Originating Adjacent to the Left Aortic Sinus of Valsalva: Electrophysiological Rationale for the Surface Electrocardiogram

Idiopathic ventricular arrhythmias (VAs) may be amenable to catheter ablation within or adjacent to the left sinus of Valsalva (LSOV). However, features that discriminate these sites have not been defined. The purpose of this study was to determine the electrocardiographic and electrophysiological features of VAs originating within or adjacent to the LSOV. We studied 48 consecutive patients undergoing successful catheter ablation of idiopathic VAs originating from the left coronary cusp (LCC, n = 29), aortomitral continuity (AMC, n = 10) and great cardiac vein or anterior interventricular cardiac vein (Epi, n = 9). A small r wave, or rarely an R wave, was typically observed in lead I during the VAs and pacing in these regions. An S wave in lead V5 or V6 occurred significantly more often during both the VAs and pacing from the AMC than during that from the LCC and Epi (p < 0.05 to 0.0001). For discriminating whether VA origins can be ablated endocardially or epicardially, the maximum deflection index (MDI = the shortest time to the maximum deflection in any precordial lead/QRS duration) was reliable for VAs arising from the AMC (100%), but was less reliable for LCC (73%) and Epi (67%) VAs. In 3 (33%) of the Epi VAs, the site of an excellent pace map was located transmurally opposite to the successful ablation site (LCC = 1 and AMC = 2). The MDI has limited value for discriminating endocardial from epicardial VA origins in sites adjacent to the LSOV probably due to preferential conduction, intramural VA origins or myocardium in contact with the LCC.

ECG Criteria to Identify Epicardial Ventricular Tachycardia in Nonischemic Cardiomyopathy

ECG criteria identifying epicardial (EPI) origin for ventricular tachycardia (VT) in nonischemic cardiomyopathy have not been determined. Endocardial (ENDO) and EPI basal left ventricle fibrosis characterizes the VT substrate. We assessed the QRS from 102 basal-superior/lateral EPI and 67 comparable ENDO pace maps in 14 patients with nonischemic cardiomyopathy. Pace mapping focused on low bipolar voltage areas. Published morphology criteria: q wave in lead I (QWLI) and no q waves in inferior leads and interval criteria: pseudo-delta wave > or =34 ms, intrinsicoid deflection time > or =85 ms, shortest RS complex > or =121 ms, and maximum deflection index > or =0.55 were assessed for ability to identify EPI origin. Sixteen EPI and 8 ENDO of the 34 mapped VTs (71%) in the study population and 14 EPI and 7 ENDO VTs from an 11-patient validation cohort were localized to basal-superior/lateral left ventricle and corroborated pacing data. A QWL1 was seen in EPI but not ENDO pace maps (91% versus 4%; P<0.001), identified 14 of 16 EPI VTs (sensitivity, 88%), and was seen in 1 of 8 ENDO VTs (specificity, 88%). None of the remaining criteria achieved similar sensitivity without specificity <50%. We identified 4 criteria (q waves in inferior leads, pseudo-delta wave > or =75 ms, maximum deflection index > or =0.59, and QWL1) having > or =95% specificity and > or =20% sensitivity in identifying EPI/ENDO origin for pace maps. This 4-step algorithm identified the origin in 109 of 115 pace maps (95%), 21 of 24 VTs (88%) in the study population, and 19 of 21 VTs (90%) in validation cohort. Morphological ECG features that describe the initial QRS vector can help identify basal-superior/lateral EPI VTs in nonischemic cardiomyopathy.

Idiopathic Epicardial Left Ventricular Tachycardia Originating Remote From the Sinus of Valsalva

Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV). In 12 of 138 patients (9%) with idiopathic VT referred for ablation, an epicardial left ventricular site of origin was identified >10 mm from the ASOV. Coronary venous mapping demonstrated epicardial preceding endocardial activation by >10 ms (41+/-7 versus 15+/-11 ms before QRS onset; P<0.001). VT induction was facilitated by catecholamines and terminated by adenosine. Ablation through the coronary veins or via percutaneous transpericardial catheterization was successful in 9 patients; 2 required direct surgical ablation as a result of anatomic constraints. No ECG pattern was specific for epicardial VT. However, slowed initial precordial QRS activation, as quantified by a novel metric, the maximum deflection index, was more useful. A delayed precordial maximum deflection index > or =0.55 identified epicardial VT remote from the ASOV with a sensitivity of 100% and a specificity of 98.7% relative to all other sites of origin (P<0.001). Although clinically underrecognized, idiopathic VT may originate from the perivascular sites on the left ventricular epicardium. The mechanism is consistent with triggered activity. It is amenable to ablation by transvenous or transpericardial approaches, although technical challenges remain. Recognition of a prolonged precordial maximum deflection index and early use of transvenous epicardial mapping are critical to avoid protracted and unsuccessful ablation elsewhere in the ventricles.