Arterialisierung epigastrischer Lappen
J. Hußrnann and E. Vaubel
Department of Plastic Surgery at the Behring-Krankenhaus (Head: Prof. Dr. E. Vaubel),
Girnpelsteig 3-5, D-1000 Berlin 37, Federal Republic of Germany
Summary. This preliminary experimental investigation revealed that arteral blood supply via the inferior epigastric vein (reversed blood flow)
nourished an epigastric skin flap well enough to survive. Histological examinations showed no differences between skin of thé flap and normal
skin (Figs. 4, 5). Free nonvascularised skin flaps (group 1) showed necroses and secondary wound healing. However, the question remains
u-isolved whether or not the blood flow is „re-reversed“ again postoperal ely and how circulation of the flap stabilizes after the first postoperative days.
Key words: Arterialization of skin flaps – AV-fistula – Reversed blood flow – Epigastric flaps – Rabbits. Carre] and Guthrie  and Jeger  have presented proposals about the reversal of b]ood flow. Erol , Nakayama  and Vouk.idis  have added further information including its experimental development, Orticochea , Vaubel , Mühlbauer , Anderl  and Stock [8) have described clinical applications.
Using the venous network as a means of arterial blood supply for a specific skin area includes two major advantages: 1) Construction of flaps
with variable angles between in- and outflow becomes possible depending · upon the kind of flap raised and upon the site of the arterie-venous fistula.
2) The relatively large diameter of the vessels used in humans might allow suturing the anastomoses without the operating microscope. Microsurgical equipment, prolonged operating time and consequent expense would no longer be necessary. Technique and Experimental Setting Inferior epigastrio flaps, 14 x 6 cm in size, were raised with different modifications (5 groups) on 15 male bastard rabbitsc o- 12 months old, 2.5-4 kg body weight, with an operation microscope type Zeiss OPMI 7-B·H-6 under Nernbutal ë-anaesthesia:
Fig. t. Flap preparation including anastomoses of proximal inferior epigastric artery (A. epig. inf.) with distal inferior epigastric vein (V. epig. inf.) and of proximal V. cpig. inf. with distal A. epig, inf.. blood ílow is indicated by arrows.
Fig. 2. Flap preparation including anastomosis of proximal A. epig. inf. with distal V. epig. inf., venous drainage via V. epig. sup. (superior epigastric vein), blood flow is indicated by arrows.
Group l : complete preparation of a ílap without blood supply (2 cases) (after preparation all flaps were put back in place and sutured)
Group 2: anastomosis of proximal inferior epigastric artery (.A, epig. inf.) with distal inferior epigastric vein (V. epig. inf) and of proximal V. epig. inf. with distal A. epig. inf.
(Fig. 1) with partial preparation of the flap (incomplete circumcision of the flap leaving 4 „rissue-skin-bridges “ approximately 2 cm each in width) to reduce postoperative ílap edema; 1 week later completepreparation of the ílap (complete circumcision and raising of the flap) (3 cases).
Group 3 · anastomoses as in group 2: arterial inflow via V. epig. inf. and venous drainage via A. epig. inf.; complete preparation of the flap (3 cases).
Group 4: 2 flap preparations in 1 rabbit: right side, flap preparation as in group 1 ; left side, flap preparation as in group 3 (1 case).
Group 5: arterial inflow via V. epi g. inf., venous drainage via V. epig. sup.; complete flap preparation (Fig. 2) (1 case). 3 other rabbits died pre- or intraoperatively, 2 rabbits died postoperatively. Postoperatively the flaps were examined for swelling, temperature and. color changes each day. 4 days to 8 weeks after the operation flaps and anastomoses were examined histologically (hematoxylineosin, elastica-Masson-Gold stain).
1) Necrosìs of varying extent was seen (in 1 case there was complete necrosis forma tion of all layers of the epidermis (Fig. 3) of the whole flap, the other 2 cases showed „jslands “ of necrosis of the flap which also included all layers of the epidermis, on some microscopic slides necrosis of the dermis was visible), secondary wound healing (in 2 cases there was infectious dehiscence of the wound edges).
Arterialízation of Epigastrio Skin Flaps 175
2) See findings in group 5.
3) See findings in group 5.
4) Right side, complete necrosis of the epidermis, secondary wound healing,
left side, as in group 3 (Fig. 6).
5) Minor eàematous swelling of the flaps for the first 1 or 2 postoperative days (on clinical aspect there was no difference between groups 2 and 3); primary wound healing in all cases, no histological differences in skin and skin appendages between flap and normal skin (Figs. 4, 5).
Discussion Necrosis and secondary wound healing of the group 1 skin flaps showed that blood supply vía the wound edges and the wound bed (capillarization) was insufficient in all flaps without microvascular anastomoses. Partial preparation (leaving „skin-bridges“) prior to raising the flap in order to reduce postoperative flap edema seemed to be redundant since clinically no significant differences in edema forma tion could be noted between the results of groups 2 and 3. · Blood supply of the flaps via arterialized veins (groups 2, 3, 4, 5) proved to be sufficient for flap survival, since clinical as well as histological examinations yield regular skin and skin appendages in all cases. Histological slides taken around the 7th postoperative day, however, showed thromboses of the anastomoses in most cases. Since all flaps looked well macro- and microscopically capillarization by that time appeared to supply the flap sufficiently. Nevertheless blood supply via anastomoses
seemed to be crucial, since all flaps without anastomoses showed varying degrees of necrosis (group 1 ). It is therefore presumed that blood supply of a flap via anastomoses is crucial in a „critical phase“ some time before postoperative day 7. We did not determine, however, the exact date of occurrence of thrombosis of the anastomoses and we do not know the earliest date thrombosis might occur and still allow survival of the flap because of sufficient capillary arterial inflow. Figure 7 summarizes the different possible patterns of arterial blood supply of the flap.
Another unsolved question is the exact pattern of capillary arteria] blood supply of the flap:
- Do capillaries grow into the flap from surrounding tissues or vice versa?
- Does capillary arterial blood flow use old capillary .. channels .. or do new capillary beds form?
- Does capillary arterial inflow increase to an amount sufficient for the flap to survive only after inflow via arterie-venous anastomoses becomes insufficient or are there 2 different mechanisms?
- Is there a „re-reversa]“ of blood flow in the flap after sufficient capillary arterial b]ood supply has been established?
- Do arterie-venous and veno-arterial anastomoses become clotted only after the „re-reversal .. of blood flow of the flap has taken place?
Fig. 7. A, decrease of arterial inflo v.,· of the flap via AV-anastomosis with time; sudden cessation of inflow when thrombosis occurs, B, increase or arterial inflow via capillaries with time: at the moment of thrombosis formation there are 2 possibilities: 1) dotted line, arterial inflow via capillaries is insufficient resulting in necrosis of the flap. 2) continuous line, arterial inflow via capillaries is sufficient leading to survival of the flap (sudden increase of the slope after thrombosis formation suggests increased arterial in.flow caused by increased capillarization due to decreased Oj-supply)
PD Dr. med. habil. Jürgen Hussmann
These and other questions remain unsolved and will be the subject of further investigations about the patterns of arterial and capillary arterial blood inflow of a skin flap. The results of these investigations might change the value of the appreciation that is given to the patency of microvascular arterio-venous anastomoses in the clinical practical application of skin flaps (compound grafts).
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