Structurally Abnormal Myocardium Underlies Ventricular Fibrillation Storms in a Patient Diagnosed With the Early Repolarization Pattern.

Objectives: The aim of this study was to investigate the mechanism underlying QRS-slurring in a patient with the early repolarization pattern in the electrocardiogram (ECG) and ventricular fibrillation (VF) storms.

Background: The early repolarization pattern refers to abnormal ending of the QRS complex in subjects with structurally normal hearts and has been associated with VF.

Methods: We studied a patient with slurring of the QRS complex in leads II, III, and aVF of the ECG and recurrent episodes of VF.

Experimental Validation of Noninvasive Epicardial and Endocardial Activation Imaging.

Background: Noninvasive imaging of cardiac activation before ablation of the arrhythmogenic substrate can reduce electrophysiological procedure duration and help choosing between an endocardial or epicardial approach. A noninvasive imaging technique was evaluated that estimates both endocardial and epicardial activation from body surface potential maps. We performed a study in isolated and in situ pig hearts, estimating activation from body surface potential maps during sinus rhythm and localizing endocardial and epicardial stimulation sites.

Transmural electrophysiological heterogeneity, the T-wave and ventricular arrhythmias.

Heterogeneous distribution of electrophysiological behavior across the heart is essential for normal cardiac function. If this heterogeneity becomes excessive it may contribute to arrhythmogenesis and sudden cardiac death. Controversy exists regarding the localization of activation and repolarization gradients in the diseased heart and how these heterogeneities contribute to arrhythmogenesis.

Dispersion in ventricular repolarization in the human, canine and porcine heart.

Dispersion in repolarization is important for the genesis of the T wave, and for the induction of reentrant arrhtyhmias. Because the T wave differs across species our intent here is to review the epicardial, endocardial and transmural repolarization patterns contributing to repolarization in whole hearts from man, dog and pig. The major points we emphasize are: transmural repolarization time gradients are small and are directed from endocardium (early) to epicardium (late) in dog and human and from epicardium to endocardium in pig; the right ventricle tends to repolarize before the left ventricle and this difference is larger in dog than in pig; a negative relation between the activation times and the repolarization times is rare in man, and absent in dog and pig.

Synchronization of repolarization by mechano-electrical coupling in the porcine heart.

Aims: The aim of this study was to evaluate the effect of increase in left ventricular (LV) pressure on repolarization and activation-recovery intervals.

Methods And Results: Six pig hearts were Langendorff-perfused. A compliant liquid-filled balloon, connected with a pressure transducer, inserted through the mitral orifice, could be filled until the required LV systolic pressure was obtained.

Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome.

Background: Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood.

Objective: The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves.

Methods: We simultaneously recorded surface ECG and unipolar electrograms at baseline and after dofetilide in a canine model of dofetilide-induced LQT2 (6 male mongrel dogs).

Disparate response of high-frequency ganglionic plexus stimulation on sinus node function and atrial propagation in patients with atrial fibrillation.

Background: In patients with atrial fibrillation (AF), the autonomic nervous system is supposed to play an role in triggering AF; however, little is known of the effect on atrial conduction characteristics.

Objective: The purpose of this study was to study the effect of ganglionic plexus (GP) stimulation during sinus rhythm on atrial and pulmonary vein conduction in patients during thoracoscopic surgery for AF METHODS: In 25 patients, the anterior right ganglionic plexus (ARGP) was stimulated (16 Hz, at 1, 2, and 5 mA). Epicardial electrograms were recorded using a 48-electrode map from the right pulmonary vein (RPV) or right atrial (RA).

Electrocardiographic T wave and its relation with ventricular repolarization along major anatomical axes.

Background: The genesis of the electrocardiographic T wave is incompletely understood and subject to controversy. We have correlated the ventricular repolarization sequence with simultaneously recorded T waves.

Methods And Results: Nine pig hearts were Langendorff-perfused (atrial pacing, cycle length 650 ms).