Experimental study on the prefabricated tram flap of rabbits with enhanced neovascularization

There are occasions when standard techniques of reconstructive surgery for traumatic injury, tumor resection, and correction of congenital anomalies cannot be used as a result of the unavailability of tissues, absence of healthy vascular pedicle or excessive morbidity in donor area. It is established that autogenous skin, muscle, bone, and other composite tissue can retain their viability in varying degree as a prefabricated `flap with vascular pedicle implantation and the survival rate of these flaps has increased with tissue expansion or PGE1 infusion. The purpose of this study was to demonstrate the reliability of the secondary or prefabricated rectus abdominis musculocutaneous flap, and to evaluate the effect of the several factors on the survival routes of these flaps. Fifty New Zealand white rabbits weighing from 250 to 350 gm were used for the study. On the abdominal area bipedicled skin flaps are elevated as a random pattern flaps and were prefabricated using with rectus muscle. The fifty flaps were studied. They were divided into the five groups as follows; group I, 10 x4 cm classic axial pattern transverse rectus abdominis muscle (TRAM ) flaps were made as a control group (n = 10); groupII, 10 x4 cm random pattern bipedicled skin flaps were prefabricated using right rectus muscle with the delay procedure(n = 10); group III, 5 x4 cm prefabricated musculocutaneous flap were made same as group II on the right, side, tissue expansion was performed on the left side (n = 10); group IV, same procedure was performed as group II, and in addition postoperative intravenous infusion of PGE1 was given(n = 10); group V, same procedure was performed as group III, and in addition postoperative intravenous infusion of PGE1 and tissue expansion was performed(n = 10). Flap survival rates of each group were evaluated and compared. The following results were obtained: 1. Survival rates of prefabricated flaps were lower than that of classic axial pattern flaps regardless of using tissue expansion and PGE1 infusion(p < 0.05). 2. In making a comparison between flap with and without PGE1 infusion, survival rates of prefabricated flaps infused with PGE1 were higher than that of flaps without PGE1 infusion. 3. The prefabricated flaps managed with tissue expansion had higher survival rates than that of flaps without using tissue expansion. 4. The survival rates of prefabricated flaps managed in combination with tissue expansion and PGE1 infusion were significantly higher than that of other groups except control group. In conclusion, this study demonstrated the significance of combiring use of tissue expansion and PGE1 infusion in a prefabricated musculocutaneous flaps as a reliable method.

The effects of surgical and chemical delay procedures on the survival of arterialized venous flaps in rabbits

An arterialized venous flap has the advantages of being thin and pliable, utilizing a large-caliber vein with a pedicle of almost any length, as well as obviating the need to sacrifice a donor artery. However, the main disadvantage of this flap is the partial necrosis of the large flap. The aim of this study was to investigate the efficacy of a surgical delay procedure and a combined surgical and chemical delay procedure on the survival of arterialized venous flaps. Ninety New Zealand white rabbits were divided into three groups: control group, a surgical delay group and a combined surgical and chemical delay group. These groups were further divided into subgroups depending on the delay period and the chemical agents. One arterialized venous flap was made from only one ear of each rabbit due to operative mortality, and 10 rabbits were distributed to each subgroup. The arterialized venous flap had an arterial inflow by anastomosis of the central auricular artery to the anterior branch of the central auricular vein and a venous outflow through the anterior marginal vein. The results were as follows ; 1. Control group : The arterialized venous flaps without any delay procedure showed complete necrosis of all flaps. 2. Surgical delay group : The mean percentages of survival areas of arterialized venous flaps were 36.6% in the 4-day delay group, 59.7% in the 7-day delay group. 3. Combined surgical and chemical delay group: a. A 3-day chemical delay in a continuation of a 4-day simultaneous surgical and chemical delay group: The mean percentages of survival areas of the arterialized venous flaps were 81.1% in the doxazosin mesylate group, 72.8% in the nitroglycerine patch group and 92.9% in a combination group of doxazosin mesylate and nitroglycerine patch. b. A 3-day chemical delay in a continuation of a 7-day simultaneous surgical and chemical delay group : The mean percentages of survival areas of the arterialized venous flaps were 94% in the doxazosin mesylate group, 90.2% in the nitroglycerine patch group and 99% in a combination group of doxazosin mesylate and nitroglycerine patch. In conclusion, the surgical delay procedure increases the percentage of survival areas of the arterialized venous flap in proportion to the delay period. The combination group of surgical and chemical delay procedure had a significant increase of the percentage of survival areas than that of the surgical delay group(p < 0.001). The best survival of the flap was obtained from the subgroup which had a 3-day chemical delay in a continuation of a 7-day simultaneous surgical and chemical delay with combined chemical agents.

Plasmatic imbibition and revascularization in venousisland flap

Several mechanisms about venous flap were proposed. Among them, plasmatic imbibition and early revascularization are supposed to be the most important factors for the survival of venous flap. Many reports about the role of plasmatic imbibition have used silastic sheet or other foreign material to block the plasmatic imbibition so that foreign body reaction might affect the survival of the flap. No experiment has been reported to examine the revascularization directly. We blocked the plasmatic imbibition by marginal resection around the venous island flap and delayed venous island flap and placing it onto the bare cartilage to exclude the effect of foreign body. We also examined the revasularization of the delay and non-delay venous island flap directly using microfil cast. As a result blocking of the plasmatic imbibition markedly decrease the survival of the flap but the survival of delay flap is about five times that of non delay flap. Revascularization was minimal at 1 week postoperative day. It is inferred that plasmatic imbibition is more important than revascularization.

The effects of surgical and chemical delay procedures on the survival of arterialized venous flaps in rabbits

An arterialized venous flap has the advantages of being thin and pliable, utilizing a large-caliber vein with a pedicle of almost any length, as well as obviating the need to sacrifice a donor artery. However, the main disadvantage of this flap is the partial necrosis of the large flap. The aim of this study was to investigate the efficacy of a surgical delay procedure and a combined surgical and chemical delay procedure on the survival of arterialized venous flaps. Ninety New Zealand white rabbits were divided into three groups: control group, a surgical delay group and a combined surgical and chemical delay group. These groups were further divided into subgroups depending on the delay period and the chemical agents. One arterialized venous flap was made from only one ear of each rabbit due to operative mortality, and 10 rabbits were distributed to each subgroup. The arterialized venous flap had an arterial inflow by anastomosis of the central auricular artery to the anterior branch of the central auricular vein and a venous outflow through the anterior marginal vein. The results were as follows ; 1. Control group : The arterialized venous flaps without any delay procedure showed complete necrosis of all flaps. 2. Surgical delay group : The mean percentages of survival areas of arterialized venous flaps were 36.6% in the 4-day delay group, 59.7% in the 7-day delay group. 3. Combined surgical and chemical delay group: a. A 3-day chemical delay in a continuation of a 4-day simultaneous surgical and chemical delay group: The mean percentages of survival areas of the arterialized venous flaps were 81.1% in the doxazosin mesylate group, 72.8% in the nitroglycerine patch group and 92.9% in a combination group of doxazosin mesylate and nitroglycerine patch. b. A 3-day chemical delay in a continuation of a 7-day simultaneous surgical and chemical delay group : The mean percentages of survival areas of the arterialized venous flaps were 94% in the doxazosin mesylate group, 90.2% in the nitroglycerine patch group and 99% in a combination group of doxazosin mesylate and nitroglycerine patch. In conclusion, the surgical delay procedure increases the percentage of survival areas of the arterialized venous flap in proportion to the delay period. The combination group of surgical and chemical delay procedure had a significant increase of the percentage of survival areas than that of the surgical delay group(p < 0.001). The best survival of the flap was obtained from the subgroup which had a 3-day chemical delay in a continuation of a 7-day simultaneous surgical and chemical delay with combined chemical agents.

Plasmatic imbibition and revascularization in venousisland flap

Several mechanisms about venous flap were proposed. Among them, plasmatic imbibition and early revascularization are supposed to be the most important factors for the survival of venous flap. Many reports about the role of plasmatic imbibition have used silastic sheet or other foreign material to block the plasmatic imbibition so that foreign body reaction might affect the survival of the flap. No experiment has been reported to examine the revascularization directly. We blocked the plasmatic imbibition by marginal resection around the venous island flap and delayed venous island flap and placing it onto the bare cartilage to exclude the effect of foreign body. We also examined the revasularization of the delay and non-delay venous island flap directly using microfil cast. As a result blocking of the plasmatic imbibition markedly decrease the survival of the flap but the survival of delay flap is about five times that of non delay flap. Revascularization was minimal at 1 week postoperative day. It is inferred that plasmatic imbibition is more important than revascularization.