What is the clinical evidence from this study?

Study design: Other. Population: Ligament of Marshall electrophysiology (n=15). Intervention: Left atrial appendage (LAA) pacing vs. Sinus rhythm and right atrial appendage pacing. Primary outcome: AM interval during LAA pacing (p=0.043).

January 1, 2009Open Access

Electrophysiological Characteristics of the Marshall Potential in Dogs Based on Anatomic Properties

Key Result

Left atrial appendage pacing in dogs separated the Marshall potential from the atrial electrogram, presenting with a prolonged AM interval (125±9 vs 80±6 ms, P=0.043 at pacing rate 350).

Structured PICO

Does left atrial appendage pacing alter the electrophysiological characteristics of the Marshall potential compared to sinus rhythm in a canine model?

Population

15 mongrel dogs of either gender, weight 20-25 kg

Intervention

Left atrial appendage (LAA) pacing and right atrial appendage (RAA) pacing; epicardial ligament of Marshall (LOM) ablation with 1-5 ml ethanol in 5 dogs

Comparator

Sinus rhythm

Outcome

AM interval (interval between atrial electrogram and Marshall potential) and Marshall potential characteristicssurrogate

Left atrial appendage pacing prolongs the AM interval and separates the Marshall potential from the atrial electrogram, which may facilitate ligament of Marshall ablation.

Main Result

Absolute Event Rate: 125% vs 80%

p-value: p=0.043

Abstract

Background: The electrophysiological characteristics of the Marshall potential is important in ligament of Marshall (LOM) ablation. Methods and Results: Marshall potential was recorded under sinus rhythm and left atrial appendage (LAA) pacing and in the first randomly selected 5 dogs (Group 1), LOM ablation was performed. Histological examination was performed in the remaining 10 dogs, which were subdivided according to the results (Groups 2, 3). During LAA pacing in Group 2, the AM interval was prolonged or shortened, whereas in Group 3 it was prolonged (125±9 vs 80±6 ms, P=0.043, when the pacing rate =350) (126±9 vs 80±6 ms, P=0.0442, when the pacing rate =450). The Marshall potential was separated from the atrial electrogram by LAA pacing in Groups 2 and 3. There was no significant difference in the AM interval during sinus rhythm and right atrial appendage pacing. Conclusions: Marshall potential has different forms on electrograms, including a prolonged AM interval, which presents with LAA pacing. This finding might be useful in LOM ablation. (Circ J 2009; 73: 444 - 450)

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