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Comparison of skeletal muscle microcirculation between clamp ischemia and microsurgical ischemia
1Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital and Medical College, Taipei, Taiwan, Republic of China.
Abstract:
We compared ischemia reperfusion injury-associated vasospasm and perfused capillary density (PCD) at the microcirculatory level between clamp ischemia and microsurgical ischemia in rat skeletal muscle. Rat cremaster muscle was prepared as an island flap, attached only with pudic-epigastric vessels branching from external iliac vessels. Two types of ischemia, with clamping only or with microvascular anastomosis, were applied at the external iliac vessels for 2 hours followed by 1-hour reperfusion before in vivo microscopic examination for hemodynamic changes. At the end of observation, small segments of the vessels at the clamping site and microsurgical anastomoses site were also harvested for histological examination. It was found that the first- and second-order arterioles had about 12-15% diameter reductions in both groups, whereas diameter reductions of the third-order arterioles were up to 37.8% in the microsurgical ischemia group, much greater than that in the clamp ischemia group (2.3%). There was also no significant difference in PCD reduction between the two groups, although the red blood cell velocity was much slower in the microsurgical ischemia group. Histological examination of the anastomosis site showed massive accumulation of polymorphonuclear neutrophils on the venous endothelium. These results suggested a different degree of endothelial damage and local leukocyte activation between microsurgical ischemia and clamp ischemia. Therefore, we conclude that clamp ischemia cannot replace microsurgical ischemia for studying microcirculatory changes in free tissue transfer.
Insights
Clamp ischemia causes less severe microvascular damage than microsurgical ischemia in rat skeletal muscle. This difference is crucial for accurately studying microcirculatory changes in free tissue transfer.
Area of Science:
- Vascular Surgery
- Microcirculation Research
- Tissue Engineering
Background:
- Ischemia reperfusion injury is a critical concern in free tissue transfer.
- Understanding microcirculatory responses to different ischemia models is essential for preclinical research.
Purpose of the Study:
- To compare microcirculatory changes, specifically vasospasm and perfused capillary density (PCD), between clamp ischemia and microsurgical ischemia in rat skeletal muscle.
- To determine the suitability of clamp ischemia as a model for microsurgical ischemia in free tissue transfer studies.
Main Methods:
- Rat cremaster muscle flaps were subjected to either clamp ischemia or microsurgical ischemia for 2 hours, followed by 1 hour of reperfusion.
- In vivo microscopy was used to assess hemodynamic changes, including arteriolar diameter and red blood cell velocity.
- Histological examination evaluated endothelial damage and leukocyte activation at ischemia sites.
Main Results:
- Microsurgical ischemia induced significantly greater diameter reduction in third-order arterioles (37.8%) compared to clamp ischemia (2.3%).
- While PCD reduction was similar, red blood cell velocity was notably slower in the microsurgical ischemia group.
- Histology revealed massive polymorphonuclear neutrophil accumulation on venous endothelium in the microsurgical ischemia group.
Conclusions:
- Clamp ischemia does not accurately replicate the microcirculatory damage observed with microsurgical ischemia.
- Microsurgical ischemia leads to more pronounced arteriolar vasospasm and endothelial inflammation.
- Clamp ischemia is inadequate for modeling microcirculatory alterations relevant to free tissue transfer research.