What does this research mean for the field?

Contractile force of the intact mammalian heart varies directly with heart rate and rhythm changes, including treppe, postextrasystolic potentiation, and mechanical alternans, independent of ventricular volume or muscle fiber length. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to understand how variations in heart rhythm and rate affect the contractile force of the isovolumic left ventricle in dogs.

December 1, 1960American Journal of Physiology-Legacy Content

Rhythm effects on contractility of the beating isovolumic left ventricle

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Why the study?

Do spontaneous changes in heart rate and rhythm affect the contractile force of the isovolumic left ventricle in dogs?

Population

Open-chested in situ dog hearts

Design

Preclinical

Authors

BLBessie L. LendrumDePaul University HFHarold FeinbergUniversity of Illinois Chicago EBE. BoydGuy's Hospital

Discussion

Member takes

Implication

Supports intrinsic contractility modulation by rate/rhythm; leaves open human translation.

Key Points

This research aims to understand how variations in heart rhythm and rate affect the contractile force of the isovolumic left ventricle in dogs.
Studied contractile force in open-chested in situ hearts recording electrocardiogram and intraventricular pressures.
Analyzed the effects of spontaneous heart rate and rhythm changes on contractile force at various heart volumes.
Observed changes like postextrasystolic potentiation with specific conditions during the experiment.
Contractile force increased with heart rate (treppe), demonstrating a clear relationship.
Postextrasystolic potentiation showed a decrease in contractile force after a premature beat followed by an increase in the next beat.
Mechanical alternans occurred alongside electrical alternans without significant changes in volume, indicating independent mechanisms.

Structured PICO

Do spontaneous changes in heart rate and rhythm affect the contractile force of the isovolumic left ventricle in dogs?

Population

Open-chested in situ dog hearts

Intervention

Spontaneous changes in heart rate and rhythm (including premature beats and electrical alternans)

Outcome

Isovolumic systolic pressure development (contractile force)surrogate

In an intact mammalian heart model, changes in heart rate and rhythm directly alter ventricular contractile force independent of muscle fiber length (Frank-Starling mechanism).

Cite This Study

Lendrum et al. (1960) studied this question.

synapsesocial.com/papers/6a1d605f750575be8d2f6fd2 https://doi.org/10.1152/ajplegacy.1960.199.6.1115

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Rhythm effects on contractility of the beating isovolumic left ventricle

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Rhythm effects on contractility of the beating isovolumic left ventricle

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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Also Consider