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Cardiac damage produced by direct current countershock applied to the heart
The American Journal of Cardiology
|February 1, 1979
Summary
Direct current shock causes myocardial damage, with injury increasing with shock intensity. Hypothermia can mitigate this damage, and technetium-99m pyrophosphate is sensitive for detecting cardiac injury.
Area of Science:
- Cardiology
- Pathophysiology
- Biomedical Engineering
Background:
- Direct current (DC) shock is used in medical procedures.
- Understanding the myocardial damage from DC shock is crucial for patient safety.
Purpose of the Study:
- To investigate the pathophysiology of myocardial damage from DC shock.
- To correlate imaging findings with tissue-level injury assessments.
Main Methods:
- Administered DC shock (10-90 watt-seconds) to canine hearts.
- Assessed injury via creatine kinase depletion, microscopy, and isotope uptake (technetium-99m pyrophosphate, thallium-201).
- Measured intramyocardial temperature and regional myocardial blood flow.
Main Results:
- Technetium-99m pyrophosphate uptake increased exponentially with shock dose and was more sensitive than thallium-201.
- Significant injury threshold identified at ~30 watt-seconds.
- Electron microscopy revealed intercalated disk dehiscence in damaged myocytes.
- Larger paddles caused superficial, widespread injury; shorter shock intervals exacerbated damage.
- Hypothermia reduced myocardial injury.
Conclusions:
- DC shock causes dose-dependent myocardial injury, characterized by intercalated disk damage.
- Technetium-99m pyrophosphate is a valuable tool for assessing DC shock-induced cardiac injury.
- Optimizing shock parameters and considering hypothermia may minimize cardiac damage.