Role of papillary muscle in the generation and maintenance of reentry during ventricular tachycardia and fibrillation in isolated swine right ventricle.
BACKGROUND
The role of papillary muscle (PM) in the generation and maintenance of reentry is unclear.


RESULTS
Computerized mapping (477 bipolar electrodes, 1.6-mm resolution) was performed in fibrillating right ventricles (RVs) of swine in vitro. During ventricular fibrillation (VF), reentrant wave fronts often transiently anchored to the PM. Tissue mass reduction was then performed in 10 RVs until VF converted to ventricular tachycardia (VT). In an additional 6 RVs, procainamide infusion converted VF to VT. Maps showed that 77% (34 of 44) of all VT episodes were associated with a single reentrant wave front anchored to the PM. Purkinje fiber potentials preceded the local myocardial activation, and these potentials were recorded mostly around the PM. When PM was trimmed to the level of endocardium (n = 4), sustained VT was no longer inducible. Transmembrane potential recordings (n = 5) at the PM revealed full action potential during pacing, without evidence of ischemia. Computer simulation studies confirmed the role of PM as a spiral wave anchoring site that stabilized wave conduction.


CONCLUSIONS
We conclude that PM is important in the generation and maintenance of reentry during VT and VF.
Kim
Y H
YH
Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, Calif, USA.
Xie
F
F
Yashima
M
M
Wu
T J
TJ
Valderrábano
M
M
Lee
M H
MH
Ohara
T
T
Voroshilovsky
O
O
Doshi
R N
RN
Fishbein
M C
MC
Qu
Z
Z
Garfinkel
A
A
Weiss
J N
JN
Karagueuzian
H S
HS
Chen
P S
PS
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D003198:Computer Simulation; D001330:Electronic Data Processing; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006352:Heart Ventricles; D066298:In Vitro Techniques; D010210:Papillary Muscles / Q000503:physiopathology*; D011342:Procainamide / Q000494:pharmacology; D011690:Purkinje Fibers / Q000502:physiology; D013552:Swine; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000503:physiopathology*; D016278:Ventricular Function, Right
D000889:Anti-Arrhythmia Agents; D011342:Procainamide