What does this research mean for the field?

In conscious dogs, increasing heart rate directly enhances left ventricular contractility by increasing the slope and zero-pressure intercept of the end-systolic pressure-volume relation, and accelerates ventricular relaxation, independent of autonomic control. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to understand how heart rate affects left ventricular performance in conscious dogs.

September 1, 1987Circulation ResearchOpen Access

Influence of heart rate on left ventricular performance in conscious dogs.

View Full Paper

Ask AI

Bookmark

Why the study?

Does increased heart rate via atrial pacing alter left ventricular performance in conscious dogs?

Population

8 chronically instrumented, conscious dogs

Comparison

Atrial pacing at 100, 120, 140, 160, 180, and… vs Control heart rate

Design

Preclinical

Authors

GFG. L. FreemanThe University of Texas Health Science Center at San Antonio WLWilliam C. LittleInterventional Cardiology RORobert A. O’RourkeCardiac Imaging

Discussion

Member takes

Implication

Rate-dependent LV enhancement occurs in conscious dogs; leaves open translation to human pacing or HF management.

Key Points

This research aims to understand how heart rate affects left ventricular performance in conscious dogs.
Eight conscious dogs were instrumented for measurement of left ventricular pressure and volume.
Atrial pacing was performed at varying heart rates (100 to 200 bpm) to assess the pressure-volume relation.
Two dogs underwent autonomic blockade to evaluate the effects of autonomic nervous system intervention.
Emax, the slope of the end-systolic pressure-volume relation, increased to 238 +/- 99% of control at peak pacing with p < 0.05.
V0, the zero pressure intercept, increased by 8.6 +/- 5.5 ml from control to peak pacing with p < 0.05.
The time constant of isovolumic pressure fall decreased by 20 +/- 10.3% at higher heart rates, indicating faster ventricular relaxation.

Structured PICO

Does increased heart rate via atrial pacing alter left ventricular performance in conscious dogs?

Population

8 chronically instrumented, conscious dogs (6 autonomically intact, 2 after autonomic blockade with 2 mg/kg i.v. propranolol and 0.2 mg/kg i.v. atropine)

Intervention

Atrial pacing at 100, 120, 140, 160, 180, and 200 bpm

Comparator

Control heart rate

Outcome

Left ventricular end-systolic pressure-volume relation (Emax and V0) and time constant of isovolumic pressure fall (T)surrogate

Increased heart rate via atrial pacing enhances contractility and accelerates relaxation, but shifts the end-systolic pressure-volume relation rightward, reducing stroke volume for any given end-diastolic volume.

Cite This Study

Freeman et al. (1987) studied this question.

synapsesocial.com/papers/6a12d154c031bb6829a75b5e https://doi.org/10.1161/01.res.61.3.455

View Full Paper

Ask AI

Bookmark

September 1, 1987Circulation ResearchOpen Access

Influence of heart rate on left ventricular performance in conscious dogs.

View Full Paper

Ask AI

Bookmark

Why the study?

Does increased heart rate via atrial pacing alter left ventricular performance in conscious dogs?

Population

8 chronically instrumented, conscious dogs

Comparison

Atrial pacing at 100, 120, 140, 160, 180, and… vs Control heart rate

Design

Preclinical

Authors

GFG. L. FreemanThe University of Texas Health Science Center at San Antonio WLWilliam C. LittleInterventional Cardiology RORobert A. O’RourkeCardiac Imaging

Discussion

Member takes

Implication

Rate-dependent LV enhancement occurs in conscious dogs; leaves open translation to human pacing or HF management.

Key Points

This research aims to understand how heart rate affects left ventricular performance in conscious dogs.
Eight conscious dogs were instrumented for measurement of left ventricular pressure and volume.
Atrial pacing was performed at varying heart rates (100 to 200 bpm) to assess the pressure-volume relation.
Two dogs underwent autonomic blockade to evaluate the effects of autonomic nervous system intervention.
Emax, the slope of the end-systolic pressure-volume relation, increased to 238 +/- 99% of control at peak pacing with p < 0.05.
V0, the zero pressure intercept, increased by 8.6 +/- 5.5 ml from control to peak pacing with p < 0.05.
The time constant of isovolumic pressure fall decreased by 20 +/- 10.3% at higher heart rates, indicating faster ventricular relaxation.

Structured PICO

Does increased heart rate via atrial pacing alter left ventricular performance in conscious dogs?

Population

8 chronically instrumented, conscious dogs (6 autonomically intact, 2 after autonomic blockade with 2 mg/kg i.v. propranolol and 0.2 mg/kg i.v. atropine)

Intervention

Atrial pacing at 100, 120, 140, 160, 180, and 200 bpm

Comparator

Control heart rate

Outcome

Left ventricular end-systolic pressure-volume relation (Emax and V0) and time constant of isovolumic pressure fall (T)surrogate

Cite This Study

Freeman et al. (1987) studied this question.

synapsesocial.com/papers/6a12d154c031bb6829a75b5e https://doi.org/10.1161/01.res.61.3.455

Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

View Full Paper

Ask AI

Bookmark