What question did this study set out to answer?

To examine how different heart rates affect coronary circulation, focusing on tachycardia and bradycardia.

January 1, 1966The Tohoku Journal of Experimental MedicineOpen Access

Effect of Heart Rate on Coronary Circulation

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Why the study?

Does altering heart rate via electrical pacing affect coronary blood flow and vascular resistance in a dog model of AV block?

Key Points

To examine how different heart rates affect coronary circulation, focusing on tachycardia and bradycardia.
Paced dog's heart at rates of 60, 120, 180, and 240 beats per minute while observing coronary blood flow and resistance.
Measured the effects of bradycardia by switching off the pacemaker at different rates.
In early tachycardia, coronary blood flow decreased while vascular resistance increased: 4.9% to 38.8% at rates of 60 to 240 bpm.
In later stages of tachycardia, blood flow increased and resistance decreased: 1.0% to 32.2% decrease with increased rates.
Bradycardia showed no change in resistance at lower rates (60, 120 bpm) but a decrease of -15.3% and -24.6% at higher rates (180, 240 bpm).

Structured PICO

Does altering heart rate via electrical pacing affect coronary blood flow and vascular resistance in a dog model of AV block?

Population

5 dogs (10-15 kg) with surgically induced atrioventricular block

Intervention

Electrical pacing of the left ventricle at rates of 60, 120, 180, and 240 beats per minute for 15-20 seconds, and subsequent cessation of pacing

Comparator

Baseline ventricular automatism (average heart rate 45 beats per minute)

Outcome

Changes in coronary blood flow and coronary vascular resistancesurrogate

Tachycardia initially increases coronary vascular resistance due to mechanical compression, but subsequently decreases it due to metabolic and humoral factors, increasing coronary blood flow.

Discussion

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Implication

Animal findings require human validation before any pacing implications; leaves open coronary flow mechanisms in clinical tachycardia.

Cite This Study

Kuramoto et al. (1966) studied this question.

synapsesocial.com/papers/6a2196c5153b2036cbf1e121 https://doi.org/10.1620/tjem.88.235

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Effect of Heart Rate on Coronary Circulation

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Effect of Heart Rate on Coronary Circulation

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider