Passive current redistribution in the heart.
BACKGROUND
Electrical stimuli produce a spatial distribution of voltage across the heart. We hypothesized that the potential difference between tissue near a stimulating electrode and a remote site could cause sufficient current to flow through a highly conductive wire connecting the two sites to directly stimulate the remote tissue.


RESULTS
In six open chest pigs, we inserted a catheter with right ventricular (RV) and superior vena cava (SVC) coil electrodes. A wire was placed with one end contacting the epicardium 10 +/- 2 mm away from the RV electrode and the other end on left ventricular (LV) epicardium 56 +/-14 mm from the RV end of the wire. Stimuli of 10 to 100 V were delivered to the RV and SVC electrodes. Potentials were recorded from two 252-electrode arrays placed over the RV and LV ends of the passive wire. The current induced in the wire was measured. A minimum stimulus of 15 +/- 6 V was needed between RV --> SVC electrodes to not only pace the RV but also to pace the LV through the passive wire as detected by the electrode array recordings. Current in the wire varied linearly with RV-SVC stimulus strength.


CONCLUSIONS
Coupling RV and LV epicardium with a passive wire while stimulating the RV endocardium induced sufficient current in the wire to synchronously pace the LV.
Girouard
S
S
Department of Biomedical Engineering, University of Alabama at Birmingham, USA.
Ideker
R
R
D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004553:Electric Conductivity; D004867:Equipment Design; D006321:Heart / Q000502:physiology*; D008955:Models, Cardiovascular; D010138:Pacemaker, Artificial; D013552:Swine; D014683:Vena Cava, Superior / Q000502:physiology; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right