What question did this study set out to answer?

To investigate how prolonged ectopic activation influences myocardial repolarization and action potential duration.

November 1, 1989Circulation

Slow and long-lasting modulation of myocardial repolarization produced by ectopic activation in isolated rabbit hearts. Evidence for cardiac "memory".

Q: What is the clinical evidence from this study?

Study design: Other. Population: Myocardial repolarization (cardiac memory) (n=9). Intervention: Ectopic pacing (right ventricular pacing) vs. Right atrial pacing. Primary outcome: Correlation between action potential duration (APD) and activation time (AT) (p=<0.0002).

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Key result

Prolonged ventricular pacing in isolated rabbit hearts produced slow changes in action potential duration that restored the inverse relation between activation time and repolarization (p<0.0002).

Population

9 isolated Langendorff-perfused rabbit hearts

Comparison

Ectopic pacing sequence: 45 minutes right atrial… vs Internal control

Design

Preclinical

Follow-up

225 minutes total pacing protocol

Authors

ACAngelika Costard‐JäckleBielefeld University BGB GoetschStanford University MAMatthias AntzElectrophysiology

Discussion

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Implication

May indicate cardiac memory in repolarization; hypothesis-generating for arrhythmia risk after prolonged pacing.

Key Points

To investigate how prolonged ectopic activation influences myocardial repolarization and action potential duration.
Studied nine isolated Langendorff-perfused rabbit hearts;
Mapped monophasic action potentials during atrial and ventricular pacing;
Analyzed the relationship between activation time and action potential duration using linear regression.
During initial atrial pacing, a significant inverse correlation between activation time and action potential duration was observed (S = -1.63; r = 0.76).
Ventricular pacing disrupted this correlation, but after 120 minutes, a slower change restored it (S = -0.71; r = 0.68; p < 0.0002).
Atrial pacing reestablished an inverse correlation after 60 minutes (S = -1.25; r = 0.53; p < 0.01).

Structured PICO

Population

9 isolated Langendorff-perfused rabbit hearts studied to examine the effect of ectopic pacing on action potential durations.

Intervention

Ectopic pacing sequence: 45 minutes right atrial pacing, followed by 120 minutes right ventricular pacing, followed by 60 minutes right atrial pacing

Comparator

Internal control (comparison between different pacing phases and timepoints within the same hearts)

Outcome

Distribution of action potential durations (APDs) and its correlation with activation time (AT)surrogate

Main Result

p-value: p=<0.0002

Prolonged changes in ventricular activation sequence induce slow, long-lasting modulation of myocardial repolarization, demonstrating the phenomenon of cardiac memory.

Cite This Study

Costard‐Jäckle et al. (1989) studied Myocardial repolarization (cardiac memory) (n=9). Ectopic pacing (right ventricular pacing) vs. Right atrial pacing was evaluated on Correlation between action potential duration (APD) and activation time (AT) (p=<0.0002). Prolonged ventricular pacing in isolated rabbit hearts produced slow changes in action potential duration that restored the inverse relation between activation time and repolarization (p<0.0002).

synapsesocial.com/papers/6a6aa1e545e10bb5bcf2c688 https://doi.org/10.1161/01.cir.80.5.1412

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Slow and long-lasting modulation of myocardial repolarization produced by ectopic activation in isolated rabbit hearts. Evidence for cardiac "memory".

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

Slow and long-lasting modulation of myocardial repolarization produced by ectopic activation in isolated rabbit hearts. Evidence for cardiac "memory".

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

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