The site of origin and the sequence of atrial activation were studied in 21 open-chested dogs anesthetized with sodium pentobarbital. Bipolar plunge electrodes were used to record atrial electrograms simultaneously with surface lead II and His bundle electrogram. In sinus rhythm the sinus node was activated first, followed sequentially by Bachmann's bundle, right atrial appendix, left atrial ap...

Catheter ablation of atrial fibrillation has emerged as a viable therapeutic option for those patients who have failed conventional medical therapy. This treatment strategy has been introduced in the past decade following the discovery of ectopic foci in the pulmonary veins capable of initiating this arrhythmia. The basis of current ablation techniques relies on inducing myocardial necrosis at ...

The atrial electrocardiogram was studied in eight patients who developed intermittent atrial fibrillation following myocardial infarction. Thirty-two episodes of onset of atrial fibrillation and 28 episodes of spontaneous cessation were observed. An atrial premature beat followed by atrial tachycardia of variable duration always preceded the onset of atrial fibrillation. Spontaneous cessation o...

The purpose of the present study was to validate the recording of left atrial activity from the pulmonary artery in man. Fifteen patients with atrial septal defect or patent foramen ovale were studied. Atrial activity was recorded simultaneously from the pulmonary artery and the high left atrium either during sinus rhythm or during paced ectopic atrial rhythm. The results have shown a close sim...

Atrial remodeling is a term introduced in 1995 to describe alterations in atrial structure or function. Atrial electrical remodeling is characterized by a reduction of refractory period and action potential duration, dispersion in refractoriness, and a reduction in conduction velocity of impulse propagation. Numerous animal and human studies have demonstrated that atrial electrical remodeling i...

Indirect evidence of a sinoatrial pacemaker shift after programmed atrial stimulation in man is presented. Following electrically induced beats, time intervals and postextrasystolic morphology of atrial electrogram and P waves were scrutinized in 30 catheterization studies. Applying premature atrial stimulation, a decrease of the interval between the last basic atrial depolarization and the sti...

The atrial vectorcardiograms of two cases of lefi atrial rhythm are described. The essential vectorcardiographic features of the usual type of this ectopic rhythm, with its variations, are discussed. The probable sites of origin of these variations are considered. It is suggested that the atrial vectorcardiogram amplified to the greatest possible magnification is the best and most direct means ...

Step-stair and banding artifacts may result from irregular ventricular rhythm caused by atrial fibrillation or premature ectopic ventricular contractions. In the case reported here, severe banding and misalignment artifacts occurred due to electrocardiographic noise mimicking ectopic beats. Severe EKG noise or pseudo-ectopic beats may cause rare but serious artifacts during cardiac-CT acquisiti...