P Piza | PubMed Health

PubMed1999

Thrombogenic stimulus causes long-term decrease of muscle flap perfusion.

This study was designed to evaluate the effect of a continuous thrombogenic insult at the feeding artery on skeletal muscle flap perfusion over 24 hours. Twelve male Sprague-Dawley rats were divided into two experimental groups. In the control group (N = 6) and in the treatment group (N = 6) the right cremaster muscle was isolated on its neurovascular pedicle and the tubular muscle flap was preserved in the medial part of the hind limb over a 24-hour period for subsequent microcirculatory observation. In the treatment group, an inverting suture was applied over half of the circumference of the ipsilateral common iliac artery to create a continuous thrombogenic stimulus. Intravital microcirculatory measurements obtained were red blood cell velocities, vessel diameters, capillary perfusion, endothelial edema index, and leukocytic-endothelial interactions. There were no statistically significant differences seen in red blood cell velocities, vessel diameters, and leukocytic-endothelial interactions between the groups. However, the inverting suture caused a significant drop in capillary perfusion from 6.23 to 1.50 capillaries per visual field (median; p = 0.002). An arterial thrombogenic insult may result in a significant decrease in capillary perfusion in muscle flaps over 24 hours although the blood flow through the thrombogenic main feeding vessel is maintained.

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PubMed1999

Effects of 8-Gy radiation on the microcirculation of muscle flaps in the rat.

Combination of radical excision and radiation has been used as a treatment modality for cancer patients. As a result, in reconstructive surgery there is often a need to harvest flaps in the vicinity of previously irradiated tissues. Radiation has been shown to cause progressive injury to the macrocirculation and microcirculation, often jeopardizing flap survival. The purpose of this study was to examine whether radiation significantly affects the sequence of leukocyte-endothelial interactions or the hemodynamics of the muscle flap in both acute and chronic situations. Male Sprague-Dawley rats (n = 42) were divided into seven groups of six rats each. Rats in group I were not irradiated. Groups II through VII received 8-Gy radiation to the right groin and scrotum. Groups II, III, and IV were examined at 4, 24 and 72 hours, respectively, and groups V, VI, and VII were examined at 1, 2 and 12 weeks. For intravital microscopy, the cremaster muscle was dissected on its neurovascular pedicle. Vessel diameters and red blood cell velocities were measured in the central cremasteric branches and branch arterioles. Capillary perfusion was evaluated in 27 visual fields of each flap. Leukocyte-endothelial interactions were evaluated by numbers of rolling, adhering, and transmigrating leukocytes in post-capillary venules. In the same postcapillary venule, we measured the endothelial edema index (constriction index). The hemodynamics of irradiated flaps did not differ significantly from those of controls. Diameter and red blood cell velocity were increased in the first- and second-order arterioles and were highest at 72 hours and 1 week. After irradiation, third-order arterioles were constricted. Radiation reduced capillary perfusion by 4.3, percent. None of the differences were statistically significant. Neither leukocyte behavior nor the constriction indices differed among the groups. In conclusion, low-dose radiation of 8 Gy does not affect hemodynamics or leukocyte-endothelial interactions of muscle flaps in the rat. Muscle tissue with intact microvasculature can be harvested for reconstructive procedures after low-dose radiation.

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