Electrical Stimulability Of Left Atrial Appendage Myocardium In Atrial Fibrillation
André Peres, Markus Hoenicka, Andreas Liebold, Hagen Gorki.
University Hospital Of Ulm, Ulm, Germany.
BACKGROUND: Multisite cardiac pacing may be a promising therapeutic option in atrial fibrillation (AF). As a first step we aimed to prove the electrical stimulability of small myocardial samples from amputated left atrial appendages in patients with AF.
METHODS: From 30 cardiac surgical patients with atrial fibrillation the left atrial appendage was harvested from the beating heart or in cardioplegic arrest. Four small samples of each amputated appendage were investigated in the organ bath. The stretched samples of about 1 cm length were paced using handmade bipolar electrodes. The contractile answers to different voltages, to simultaneous stimulation and the influence of adrenaline were measured.
RESULTS: The time point of harvesting had no influence on the stimulability of the samples. In 11 samples from 9 appendages we obtained a contractile response to pacing with 60 bpm. After application of adrenaline into the bathing buffer solution the response improved to 90 samples from 29 appendages. We observed a proportional relation between the voltage and the contractile answer. Compared to single sample arrangement, simultaneous parallel circuit stimulations with 18 V of up to the 4 samples of the same appendage resulted in similar contractile answers.
CONCLUSIONS: Small samples of atrial myocardial tissue from patients with atrial fibrillation showed rhythmic response to electrical pacing. In vitro studies on larger myocardial tissue are planned before multisite pacing investigations in vivo are warranted.
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