Long-duration ventricular fibrillation exhibits 2 distinct organized states.

Background: Previous studies showed that endocardial activation during long-duration ventricular fibrillation (VF) exhibits organized activity. We identified and quantified the different types of organized activity.

Methods And Results: Two 64-electrode basket catheters were inserted, respectively, into the left ventricle and right ventricle of dogs to record endocardial activation from the endocardium during 7 minutes of VF (controls, n=6).

Different types of long-duration ventricular fibrillation: can they be identified by electrocardiography.

We tested the hypothesis that after 2 minutes of ventricular fibrillation (VF), periods of highly organized activations occur on the endocardium, arising from an intramural mother rotor or triggered activity originating in the Purkinje fibers. In 6 anesthetized dogs, we recorded electrically induced VF from two-thirds of the endocardium with a 64-electrode basket catheter. In another 12 dogs, the study was repeated with the addition of the early afterdepolarization blocker pinacidil in 6 animals and the delayed afterdepolarization blocker flunarizine in the other 6 animals.

Evidence that activation following failed defibrillation is not caused by triggered activity.

Background: Earliest postshock activation following failed defibrillation shocks slightly lower than the defibrillation threshold (DFT) in large animals appears to arise from a focus. We tested the hypothesis that these foci are caused by early or delayed afterdepolarizations (EADs or DADs) by performing epicardial electrical mapping and giving the EAD inhibitor pinacidil or the DAD inhibitor flunarizine to see if the foci were extinguished or altered in timing or location.

Methods And Results: A sock containing 504 electrodes was placed over the entire ventricular epicardium of 12 open-chested pigs.

Decrease in fluoroscopic cardiac silhouette excursion precedes hemodynamic compromise in intraprocedural tamponade.

Background: Acute pericardial tamponade is a life-threatening complication of invasive cardiovascular procedures. Survival depends on early recognition and treatment. A diagnostic test to detect pericardial fluid accumulation before a significant fall in blood pressure and without contamination of the sterile field would be valuable.

Activation sequences following failed atrial defibrillation.

Objectives: The purposes of this study were to examine the first activations following atrial defibrillation shocks to help understand how and where atrial fibrillation (AF) relapsed following failed shocks and to assess the difference in postshock activation between failed and successful shocks.

Background: While many studies have investigated the mechanism of ventricular defibrillation, much less is known about the mechanisms of AF.

Methods: Sustained AF was induced electrically after pericardial infusion of methylcholine in 10 sheep.

Reduction of the internal atrial defibrillation threshold with balanced orthogonal sequential shocks.

Introduction: The aim of this study was to determine the atrial defibrillation threshold (ADFT) of a first shock across the standard right atrium (RA) to distal coronary sinus (dCS) configuration followed by a second shock along the atrial septum with a standard sequential waveform (the second shock leading edge equaled the first shock trailing edge) and a balanced sequential waveform (the leading edges of both shocks were equal).

Methods And Results: In nine sheep atrial fibrillation was induced with acetyl-beta-methylcholine and burst pacing. A catheter was placed with electrodes in the dCS, proximal coronary sinus (pCS), and RA.