An acute model for atrial fibrillation arising from a peripheral atrial site: evidence for primary and secondary triggers.

Background: We previously demonstrated that acetylcholine (Ach) injected into cardiac ganglionated plexi (GP) causes pulmonary vein (PV) ectopy initiating atrial fibrillation (AF).

Objective: To determine the effects of Ach applied at non-PV sites.

Methods: Overall, 54 dogs were anesthetized with Na-pentobarbital.

Experimental model for paroxysmal atrial fibrillation arising at the pulmonary vein-atrial junctions.

Background: The mechanism(s) by which pulmonary veins (PVs) become ectopically active and subsequently initiate and sustain atrial fibrillation (AF) remains poorly understood.

Objectives: The purpose of this study was to produce an acute canine model of paroxysmal AF arising from the PVs.

Methods: In 11 dogs, a thoracotomy was performed and a 26-gauge needle with a polyethylene tube attached was inserted into a fat pad containing autonomic ganglia at the base of the PV.

Experimental model of inappropriate sinus tachycardia: initiation and ablation.

Objective: The purpose of the present study was to develop an experimental model of inappropriate sinus tachycardia (IST) by injecting a catecholamine into a fat pad containing autonomic ganglia (AG) innervating the sinus node (SN).

Methods: Initial protocols in 3 groups of pentobarbital anesthetized dogs consisted of (1) slowing the heart rate (HR) by electrical stimulation of AG in the fat pad; (2) the effect of intravenous injection of epinephrine (0.1-0.

Variability of AV nodal potentials recorded, in vivo: direct demonstration of dual AV nodal physiology.

Objectives Of Study: We developed a method to record extracellular A-V nodal potentials in the beating dog heart, in vivo.

Methods: In eleven Na-pentobarbital anesthetized, open-chest dogs, an octapolar electrode catheter (2 mm rings, 2 mm spacing) was inserted through a purse-string suture in the coronary sinus (CS) distal to the ostium and positioned electrographically so that the tip electrode recorded a His bundle (Hb) potential.

Results: Stable recordings of A-V nodal potentials (amplitude, 178 +/- 94 microV; duration 78 +/- 26 msec) were consistently made during sinus rhythm from the second and/or third bipolar pairs of electrodes.

Endovascular stimulation within the left pulmonary artery to induce slowing of heart rate and paroxysmal atrial fibrillation.

Objective: In recent years there have been many reports dealing with basic models for sustained atrial fibrillation (AF), however few animal models exist for paroxysmal AF which closely simulate that seen clinically.

Methods: In 12 dogs, anesthetized with sodium pentobarbital, a right thoracotomy was performed. We stabilized a basket electrode catheter within the left pulmonary artery (LPA) through a purse string suture in the right ventricle.

Is there longitudinal dissociation in the undamaged his bundle? In vitro studies in the normal canine heart.

We investigated the concept of longitudinal dissociation in the His-Purkinje system in vitro. Hearts were excised from the eleven anesthetized dogs and a septal preparation containing the exposed His bundle and the entire right bundle branch and left bundle branch were displayed in a two-dimensional arrangement pinned to the bottom of a superfusion chamber. Tyrodes solution, gassed with 95% O2 and 5% CO2, at 37 degrees C was continuously passed over the preparation.