What question did this study set out to answer?

To evaluate hemodynamic responses to submaximal exercise and brief ischemia in dogs with healed myocardial infarctions to distinguish animals susceptible to sudden cardiac death.

September 1, 1985Journal of Applied Physiology

Cardiac response to submaximal exercise in dogs susceptible to sudden cardiac death

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To evaluate hemodynamic responses to submaximal exercise and brief ischemia in dogs with healed myocardial infarctions to distinguish animals susceptible to sudden cardiac death.
Studied 38 chronically instrumented mongrel dogs with healed anterior wall myocardial infarctions during submaximal treadmill exercise.
Applied a 2-minute coronary occlusion during and immediately following exercise, identifying 19 dogs susceptible to ventricular fibrillation and 19 resistant dogs.
Measured heart rate, left ventricular pressures, and coronary blood flow at baseline and following beta-adrenergic blockade with propranolol.
Susceptible dogs demonstrated significantly higher heart rates (201.4 ± 5.1 vs. 176.2 ± 5.6 beats/min) and left ventricular end-diastolic pressure (19.4 ± 1.1 vs. 12.3 ± 1.7 mmHg), but lower left ventricular systolic pressure (136.9 ± 7.9 vs. 154.6 ± 9.8 mmHg) during exercise at 6.4 kph and 8% grade.
Propranolol reduced the difference in heart rate between susceptible and resistant dogs (163.4 ± 4.7 vs. 150.3 ± 6.4 beats/min) but exacerbated left ventricular pressure disparities (LVEDP: 28.4 ± 2.1 vs. 19.6 ± 3.0 mmHg; LVSP: 122.2 ± 8.1 vs. 142.8 ± 10.7 mmHg).

Structured PICO

Population

38 mongrel dogs with healed anterior wall myocardial infarctions, chronically instrumented

Intervention

Submaximal exercise stress test with a 2 min coronary occlusion initiated during the last minute of exercise, with and without beta-adrenergic receptor blockade (propranolol)

Comparator

Dogs susceptible to ventricular fibrillation (n=19) vs. dogs resistant to ventricular fibrillation (n=19)

Outcome

Hemodynamic response (heart rate, left ventricular pressure, LVP rate of change, and coronary blood flow)surrogate

Animals vulnerable to ventricular fibrillation during exercise and transient ischemia exhibit a greater degree of left ventricular dysfunction and increased sympathetic efferent activity.

Discussion

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Implication

Exercise-induced hemodynamic disparities may mark VF susceptibility in this post-MI canine model; hypothesis-generating and should not yet change clinical practice.

Cite This Study

Billman et al. (1985) studied this question.

synapsesocial.com/papers/6a815b1c6034bcd5e8690bd6 https://doi.org/10.1152/jappl.1985.59.3.890

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Implication

Exercise-induced hemodynamic disparities may mark VF susceptibility in this post-MI canine model; hypothesis-generating and should not yet change clinical practice.

Cardiac response to submaximal exercise in dogs susceptible to sudden cardiac death

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Cardiac response to submaximal exercise in dogs susceptible to sudden cardiac death

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider