Quantitative Evaluation of a Directly Depolarized Area Induced by High-Output Pacing on the Cardiac Muscle

Abstract

Quantitative information is needed on the directly depolarized area (DDA) induced by high-output energy during a precise mapping procedure to detect the origin of a tachycardia. In the present study, a DDA caused by high-output energy was quantitatively evaluated in the exposed canine heart. In 8 dogs, the right atrial and ventricular surfaces were exposed through a right thoracotomy and pacing with various outputs was delivered from the epicardial surface. A comb-shaped 16 polar electrode array and/or a 224 polar mat electrode array were used for recording the epicardial electrograms. The local activation time was measured at each electrode site, and the relationship of the distance between the electrode location from the pacing site and the local activation time was plotted and fitted to a primary regression line. The intercept of the regression line on the horizontal axis was defined as the radius of the 'DDA' and this was evaluated at each pacing output. The radius of the DDA was 0.6+/-0.1 mm with a 2 V and 3.8+/-0.2 mm with a 10 V output when it was evaluated in a direction perpendicular to the fiber orientation of the pectinate muscle, 0.8+/-0.1 mm with a 2 V and 4.1+/-0.3 mm with a 10 V output in a direction parallel to the pectinate muscle fiber orientation, and 0.9+/-0.3 mm with a 2 V and 3.6+/-0.5 mm with a 10 V output in the right ventricle. The DDA extended according to the increase in stimulation outputs at all sites, and there was no significant difference in the pacing site or the direction of the stimulation propagation. The DDA caused by high-output energy is a purely physical phenomenon that depends only on stimulation output and tissue resistance. The diameter of the DDA exceeded 4 mm (ie, the size of a standard tip electrode for catheter ablation) when pacing was delivered with an output greater than 6 V.

Effect of Pilsicainide on Atrial Electrophysiologic Properties in the Canine Rapid Atrial Stimulation Model. A Possible Suppressive Effect on Atrial Electrical Remodeling.

“…In the control group, consistent with previous studies, [13][14][15][16][17] the progression of atrial pacing induced electrical remodeling was inhomogeneous, depending on the atrial site assessed. Shortening of the AERP was larger at the RAA and LA sites than at the other sites and as a result, the AERPd was increased early during the rapid pacing phase and then decreased during the recovery phase.…”

“…[17][18][19] Four pairs of stainless steel wire electrodes were sutured onto the epicardial surface of the right atrial appendage (RAA), Bachmann's bundle (BB), the right atrium close to the inferior vena cava (IVC) and the center of the left atrial free wall (LA) (Fig 1A). The other ends of the wire electrodes were tunneled subcutaneously and exposed at the back of the neck for the electrophysiological measurements in the later studies.…”

Arrhythmogenic Difference Between the Left and Right Atria During Rapid Atrial Activation in a Canine Model of Atrial Fibrillation

“…All measurements were performed after pharmacological blocking of the autonomic nervous system by infusing atropine 0.04 mg/kg and propranolol 0.2 mg/kg. 13,18 Atrial Diastolic Threshold At the time of each evaluation of the electrophysiological parameters, the atrial diastolic threshold was measured at the 4 atrial sites by delivering a 300-ms cycle length pacing with a pulse width of 2 ms. 19 ERP The atrial ERP was measured at the 4 atrial sites with basic drive cycle lengths (BCL) of 300, 200, and 150 ms at the time of each evaluation as described above.…”

“…This pacing was delivered at 4-fold the diastolic threshold with a pulse width of 2 ms. 19 We defined AF as a spontaneous irregular atrial rhythm lasting longer than 3 s. 18 Atrial burst pacing to induce AF was delivered 5 times at each pacing site at each evaluation point throughout the entire protocol.…”

Verapamil Suppresses the Inhomogeneity of Electrical Remodeling in a Canine Long‐Term Rapid Atrial Stimulation Model

“…In ten adult beagle dogs weighing 11–15 kg, the cardiac surface was exposed via a right thoracotomy under pentobarbital anesthesia (30 mg/kg body weight, intravenously [IV]) and mechanical ventilation (Model SN‐480‐5, Shinano Manufacturing, Tokyo, Japan) with room air 15–17 . Four pairs of stainless steel wire electrodes were sutured on the epicardial surface of the right atrial appendage (RAA), the right atrium close to the inferior vena cava (IVC), Bachmann's bundle, and the center of the left atrial (LA) free wall (Fig.…”