Yunlong Xia

T(peak)-T(end) Interval as an Index of Global Dispersion of Ventricular Repolarization: Evaluations Using Monophasic Action Potential Mapping of the Epi- and Endocardium in Swine.

AbstractThe ECG interval from the peak to the end of the T wave (Tpeak-Tend) has been used as an index of transmural dispersion of ventricular repolarization (DVR). The correlation between the Tpeak-Tend interval and the global DVR, however, has not been well-evaluated. Methods: Monophasic action potentials (MAPs) were recorded from 51 ± 10 epicardial and 64 ± 9 endocardial sites in the left ventricles of 10 pigs, and from 41 ± 4 epicardial and 53 ± 2 endocardial sites in the right ventricles of 2 of the 10 pigs using the CARTO mapping system. The end of repolarization times over the epi- and endocardium were measured, and the end of repolarization dispersions over the epicardium (DVR-epi), over the endocardium (DVR-endo) and over both (DVR-total) were calculated. The QTpeak, QTend and Tpeak-Tend intervals as well as the QTpeak and QTend dispersions were obtained from the simultaneously recorded 12-lead ECG. Results: The maximal Tpeak-Tend intervals (57 ± 7 ms) were consistent with the DVR-total (58 ± 11 ms, p > 0.05), and significantly correlated with the DVR-total (r = 0.64, p < 0.05). However, the mean Tpeak-Tend intervals (44 ± 5 ms), and Tpeak-Tend intervals from lead II (41 ± 6 ms) and V5 (43 ± 5 ms) were all significantly smaller than and poorly correlated with the DVR-total, as were the QTpeak and QTend dispersions (15 ± 2 ms vs. 21 ± 4 ms). Conclusion: The maximal Tpeak-Tend interval may be used as a noninvasive estimate for the global DVR, but not the QTpeak and QTend dispersions, nor the mean Tpeak-Tend interval and that from a single lead.

Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: validation of P-wave morphology using electroanatomic mapping in man.

BACKGROUND Different P-wave morphologies during sinus rhythm as displayed on standard ECGs have been postulated to correspond to differences in interatrial conduction. OBJECTIVE The purpose of this study was to evaluate the hypothesis by comparing P-wave morphologies using left atrial activation maps. METHODS Twenty-eight patients (mean age 49 +/- 9 years) admitted for ablation of paroxysmal atrial fibrillation were studied. Electroanatomic mapping of left atrial activation was performed at baseline during sinus rhythm with simultaneous recording of standard 12-lead ECG. Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology. The morphology was subsequently classified into one of three predefined types. All analyses were blinded. RESULTS The primary left atrial breakthrough site was the fossa ovalis in 8 patients, Bachmann bundle in 18, and coronary sinus in 2. Type 1 P-wave morphology was observed in 9 patients, type 2 in 17, and type 3 in 2. Seven of eight patients with fossa ovalis breakthrough had type 1 P-wave morphology, 16 of 18 patients with Bachmann bundle breakthrough had type 2 morphology, and both patients with coronary sinus breakthrough had type 3 P-wave morphology. Overall, P-wave morphology criteria correctly identified the site of left atrial breakthrough in 25 (89%) of 28 patients. CONCLUSION In the vast majority of patients, P-wave morphology derived from standard 12-lead ECG can be used to correctly identify the left atrial breakthrough site and the corresponding route of interatrial conduction.

Atrial average conduction velocity in patients with and without paroxysmal atrial fibrillation

To evaluate intra‐atrial conduction delay in patients with atrial fibrillation (AF) via calculation of conduction velocities (CVs) of the right and left atria.

Epicardial and endocardial dispersion of ventricular repolarization. A study of monophasic action potential mapping in healthy pigs.

Objectives. To investigate the total dispersion of ventricular repolarization of the epi- and endocardium. Design. Monophasic action potentials (MAP) were recorded from 211±54 (151–353) left and right ventricular epi- and endocardial sites during atrial pacing in 10 pigs using the CARTO system. The activation time (AT), MAP duration (MAPd) and end of repolarization time (EOR) were measured. Results. The total dispersion of AT, EOR and MAPd, defined as the maximal differences of these parameters over both the epi- and endocardium, were 57±10, 84±20, and 75±21 ms respectively and were significantly larger than the respective epi- and endocardial dispersions (p<0.05). The epicardial dispersion of AT, EOR and MAPd of both the right and left ventricles were significantly larger than that of each ventricle alone (p<0.02). Sternotomy did not affect these dispersion parameters. Conclusion. Detailed mapping of epicardial repolarization in vivo using the MAP mapping technique is feasible. Both the epi- and endocardium of the two ventricles contribute significantly to the total dispersion of repolarization.

Ventricular repolarization sequences on the epicardium and endocardium. Monophasic action potential mapping in healthy pigs

UNLABELLED To investigate repolarization sequence, monophasic action potentials were recorded from a mean of 153 ± 54 left and right ventricular epicardial and endocardial sites in 10 pigs using the CARTO mapping system (Biosense Webster, Waterloo, Belgium). The activation time and end-of-repolarization (EOR) time were measured and 3-dimensional maps of activation and repolarization sequences constructed. RESULTS In 8 of 9 pigs, both the activation and EOR times appeared first in the septum and last in the latero-basal areas on the endocardium, not on the epicardium. The EOR followed the activation sequence, both on the epicardium (in 8/9 pigs) and endocardium (in 8/8 pigs). The maximal EOR differences were 84 ± 20 ms, whereas the local EOR differences between paired sites against each other on the left ventricular epicardium and endocardium were 11 ± 9 ms in the apex and 12 ± 12 ms in the anterior wall. CONCLUSION The EOR follows the activation sequence both on the epicardium and endocardium. The apico-basal gradients are predominant repolarization gradients, as compared with the epicardial-endocardial gradients.