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Improved tolerance of the pediatric myocardium to brain death
D S Peterseim1, C H Meyers, D M Craig
1Department of Surgery, Duke University Medical Center, Durham, NC 27710.
Insights
Pediatric myocardium in pigs shows resilience to brain death, unlike adult hearts. This study indicates that young hearts may better withstand the cardiac dysfunction associated with brain death.
Area of Science:
- Cardiology
- Physiology
- Pediatric Research
Background:
- Brain death significantly impairs adult left ventricular function.
- The impact of brain death on pediatric myocardium remains less understood.
Purpose of the Study:
- To investigate the sensitivity of pediatric porcine myocardium to brain death.
- To compare the cardiac response of young pigs to brain death with adult models.
Main Methods:
- Left ventricular pressure and dimensions were measured in 1-month-old pigs.
- Brain death was induced in a subset of pigs; controls were maintained.
- Preload recruitable stroke work relationships were analyzed over 6 hours.
Main Results:
- Brain-dead pigs showed variable contractility indices, with a notable decrease at 6 hours (87% of baseline).
- Control pigs maintained stable contractility (111% of baseline at 6 hours).
- Pediatric myocardium demonstrated some resilience compared to adult models, though dysfunction occurred.
Conclusions:
- The pediatric porcine heart exhibits a different response to brain death compared to adult hearts.
- Further research is needed to fully elucidate the mechanisms of cardiac adaptation in pediatric brain death.
Abstract:
The occurrence of brain death has been shown to significantly diminish left ventricular function in the adult porcine model. This study examined whether the pediatric myocardium is as sensitive as the adult myocardium to the detrimental effects of brain death in the porcine model. Left ventricular intracavitary pressure and major and minor axis epicardial dimensions were measured in eleven 1-month old pigs (7.5 to 10 kg) during a vena caval occlusion. Brain death was induced in six pigs by acutely ligating the brachiocephalic and left subclavian arteries. The remaining five pigs served as controls. Data were then collected every hour for 6 hours. The plot of the stroke work versus the end diastolic volume, called the preload recruitable stroke work relationship, was determined from the measured pressure and calculated intracavitary volume data. The slope of this linear relationship is an index of contractility, and the x intercept (Vo) is an index of diastolic mechanics. At each hour after instrumentation two vena caval occlusions were performed, and the mean slope of the preload recruitable stroke work line was calculated as a percentage of the baseline slope in both the brain-dead and control group. The mean values from the brain-dead pigs were 118%, 138%, 126%, 154%, 123%, and 87% of the baseline value for the 6 hours after brain death. The mean control values were 128%, 117%, 133%, 123%, 114%, and 111% of baseline for the 6 hours after instrumentation alone.(ABSTRACT TRUNCATED AT 250 WORDS)