Intracoronary infusion of catecholamines causes focal arrhythmias in pigs.
BACKGROUND
Acute ischemia causes myriad changes including increased catecholamines. We tested the hypothesis that elevated catecholamines alone are arrhythmogenic.


RESULTS
A 504 electrode sock was placed over both ventricles in six open-chest pigs. During control infusion of saline through a catheter in the left anterior descending coronary artery (LAD), no sustained arrhythmias occurred, and the refractory period estimated by the activation recovery interval (ARI) was 175 +/- 14 ms in the LAD bed below the catheter. After infusion of isoproterenol at 0.1 microg/kg/min through the catheter, the ARI in this bed was significantly reduced to 109 +/- 10 ms. A sharp gradient of refractoriness of 43 +/- 10 ms was at the border of the perfused bed. Sustained monomorphic ventricular tachycardia occurred after drug infusion in the perfused bed or near its boundary in all animals with a cycle length of 329 +/- 26 ms and a focal origin. The maximum slope of the ARI restitution curve at the focal origins of the tachyarrhythmias was always <1 (0.62 +/- 0.15). Similar results with a focal arrhythmia origin occurred in two additional pigs in which intramural mapping was performed with 36 plunge needle electrodes in the left ventricular perfused bed.


CONCLUSIONS
Regional elevation of a catecholamine, which is one of the alterations produced by acute ischemia, can by itself cause tachyarrhythmias. These arrhythmias are closely associated with a shortened refractory period and a large gradient of the spatial distribution of refractoriness but not with a steep restitution curve.
Doppalapudi
Harish
H
Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Jin
Qi
Q
Dosdall
Derek J
DJ
Qin
Hao
H
Walcott
Gregory P
GP
Killingsworth
Cheryl R
CR
Smith
William M
WM
Ideker
Raymond E
RE
Huang
Jian
J
D000818:Animals; D002395:Catecholamines / Q000008:administration & dosage*; D005260:Female; D007261:Infusions, Intra-Arterial; D008297:Male; D013552:Swine; D014693:Ventricular Fibrillation / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology*
D002395:Catecholamines