Related Experiment Videos
Effects of brain death on myocardial function and ischemic tolerance of potential donor hearts
G Szabó1, C Sebening, T Hackert
1Department of Cardiac Surgery, University of Heidelberg, Germany.
Insights
Brain death causes hemodynamic instability due to altered loading conditions, not primary cardiac dysfunction. Donor hearts show preserved function and tolerance to ischemia after preservation, suggesting reversibility.
Area of Science:
- Cardiovascular Physiology
- Transplantation Medicine
- Neurocritical Care
Background:
- Brain death is associated with hemodynamic instability in organ donors.
- The impact of brain death on donor heart function and ischemic tolerance is debated.
- Investigating brain death and cardiac preservation interactions is crucial for transplantation outcomes.
Purpose of the Study:
- To perform a load-independent analysis of cardiac function following brain death.
- To assess the influence of brain death and cardiac preservation on postischemic heart function.
- To determine if brain death causes irreversible myocardial damage or primary cardiac dysfunction.
Main Methods:
- Brain death was induced in 12 dogs using a subdural balloon; 12 served as controls.
- Hearts were explanted after 2 hours and perfused immediately or after 4 hours of cold ischemic storage.
- In situ and ex vivo hemodynamic parameters, including pressure-volume relationships and myocardial oxygen consumption, were measured.
Main Results:
- Despite in situ hemodynamic deterioration in brain-dead animals, ex vivo myocardial function was comparable to controls.
- Both control and brain-dead hearts demonstrated complete functional recovery after hypothermic ischemic preservation and reperfusion.
- Low mean aortic pressure and decreased maximal dP/dt were observed in brain-dead donors in situ.
Conclusions:
- Hemodynamic instability post-brain death likely results from altered loading conditions, not irreversible myocardial damage.
- Brain death does not appear to impair the heart's tolerance to ischemic preservation.
- Donor hearts maintain functional integrity and recover well after preservation, regardless of brain death status.
Background:
An increasing number of experimental and clinical studies reports hemodynamic instability in the donor organism after brain death. However, the relative importance of brain death-related cardiac dysfunction on posttransplantation cardiac function and the reversibility of the observed changes remain controversial. In this study a load-independent analysis of cardiac function after brain death was performed. Special interest was focused on a possible interactive influence of brain death and cardiac preservation on postischemic cardiac function.
Methods:
In 12 anesthetized dogs, brain death was induced by inflation of a subdural balloon; 12 sham-operated animals served as control subjects. After a 2-hour observation in situ, the hearts were explanted and perfused parabiotically either immediately or after hypothermic ischemic preservation (4 hours, 4 degrees C). Heart rate, cardiac output, left ventricular pressure, the maximum of left ventricular pressure development and aortic pressure were measured in situ. In addition, the slope of the end-systolic pressure-volume relationship, coronary blood flow, and myocardial oxygen consumption were estimated in the cross-circulated hearts.
Results:
In spite of a brain death-associated hemodynamic deterioration in situ (expressed as low mean aortic pressure and significant decrease of maximal dP/dt), myocardial function was similar to control after explantation, if assessed ex vivo. Furthermore, after hypothermic ischemic preservation and reperfusion, complete functional recovery of control and brain-dead hearts could be observed.
Conclusions:
These data indicate that hemodynamic instability after brain death may rather reflect altered loading conditions than irreversible myocardial damage or primary cardiac dysfunction. Furthermore, there is no evidence for a brain death-related impairment of ischemic tolerance.