Morphometric identification of luminal narrowing of myocardial capillaries after cardioplegic arrest
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Published on: December 11, 2016
1Department of Public Health, Kaohsiung Medical University, Taiwan. yfchen@cc.kmu.edu.tw
Insights
Hypothermic blood cardioplegic arrest causes endothelial cell swelling and capillary lumen narrowing in the heart. This progressive decrease in capillary lumen impacts myocardial microcirculation during cardiac surgery.
Area of Science:
- Cardiovascular Research
- Cardiac Surgery
- Microcirculation
Background:
- Capillary function differs from arterioles due to lack of smooth muscle.
- Investigating myocardial capillaries post-cardioplegic arrest is crucial.
Purpose of the Study:
- To assess the impact of hypothermic blood cardioplegic arrest and reperfusion on myocardial capillaries.
- To understand changes in capillary structure and lumen in cardiac operation patients.
Main Methods:
- Stereologic morphometric analysis of myocardial capillary biopsies (n=27).
- Measurements included luminal surface area and endothelial cytoplasmic surface area.
- Biopsies taken pre-ischemia, during ischemia, and post-reperfusion.
Main Results:
- Significant endothelial cell swelling observed after ischemia and reperfusion (p=0.0007).
- Remarkable reduction in capillary luminal surface area post-ischemia and reperfusion (p=0.0008).
- No significant change in total cross-sectional surface area of capillaries (p=0.152).
Conclusions:
- Endothelial cell swelling is the primary cause of capillary lumen narrowing.
- Progressive capillary lumen decrease occurs during and after cardioplegic arrest.
- Findings highlight critical microcirculatory changes in cardiac surgery patients.
Background:
Because there is no smooth muscle cell surrounding the capillary endothelial cells, the effect of coronary microcirculation at the capillary level following cardioplegic arrest and reperfusion would be much different from that of resistant arterioles. We therefore studied the effect of hypothermic blood cardioplegic arrest and subsequent reperfusion on the myocardial capillaries in cardiac operation patients.
Methods:
Twenty-seven patients who underwent cardiac operations were included in this study. Three sequential biopsies (preischemia, ischemia, and reperfusion) were obtained from the right atrium. This study was restricted to blood vessels with a diameter of less than 8 microns. Ten randomly selected capillaries from each biopsy were measured for luminal surface area, endothelial cytoplasmic surface area, and total cross-sectional surface area of capillaries.
Results:
From stereologic morphometric studies, the serial changes in total cross-sectional surface area were not statistically significant (p = 0.152). However, there was a significant swelling of endothelial cytoplasm following ischemia and reperfusion (p = 0.0007). Meanwhile, changes in luminal surface area of capillaries following ischemia and reperfusion were also remarkable (p = 0.0008).
Conclusions:
The most striking finding of this study was the progressive decrease in capillary lumen during ischemia and after reperfusion. The swelling of endothelial cells is a major determinant of luminal narrowing of capillaries in patients receiving cardioplegic arrest.
