Pedal and distal lower leg bypasses with a distal arteriovenous fistula

EurJ VascSurg 1,251-258 (1987)

Pedal and Distal Lower Leg Bypasses W i t h a Distal Arteriovenous Fistula Dennis P. van Berge Henegouwen, GOnter Stelzer,* Thomas Dautzenberg, Lutz Helmig and Uvve Ehresmann Klinik Oberwald, Fachklinik ffir Gefiifl und Enddarmerkrankungen, Postfach 1149, 6 4 2 4 Grebenhain-1, West Germany In Jbrty patients 41 feet were re vascularised by means of distal tibial (the distal 10 cm of the lower leg) (17) or pedal bypasses (24). Angiographieally the preoperative state was best defined as a lower leg block (LLB ); All three arteries showing occlusions at several levels, leaving only isolated functioning arterial segments in the distal leg or foot with relatively good femoral and popliteal arteries. As might be expected this condition was mainly found in diabetics (75%). Only feet with severe rest pain (4) or rest pain with gangrene (37) were operated upon. To improve the distal outflow a side-to-side arteriovenous fistula (A VF) was added to the distal anastomosis. With a mean follow-up of 21 months (1-40 months) the limb salvage rate was 79% and the patency rate 67%. Special problems were experienced with cellulitis of the foot, causing the loss of three feet despite an open bypass and sufficient revascularisation. Furthermore, occlusion of the bypass after healing of the lesion did not necessarily mean a recurrence of gangrene. As this series shows, even in angiographically apparently hopeless cases, a bypass to the foot can prevent an otherwise unavoidable amputation. Key Words: Distal bypass; Arteriovenous fistula; Pedal bypass.

Introduction

Patients

Reconstructive surgery of the distal arterial system is limited by the poor run-off capacity of the vessels at this level. Early occlusion of bypasses in this area are mainly caused by a low flow in the bypass. 1° Other problems include the small calibre of the vessels and severe pathology such as mediasclerosis and small vessel arteriosclerosis. Under these conditions revascularisation of the foot does not seem very promising. By introducing a side-to-side arteriovenous fistula (AVF) integrated into the distal anastomosis of the bypass it was hoped to solve at least one of these problems. This series reports our early experiences of 41 bypasses to the foot or to the last 10 cm of the lower leg.

Between the first of November 1983 and July 1st 1986 forty patients with a mean age of 67.9 years ( 4 6 - 8 7 years) were treated. The sex distribution was: 16 female to 24 male patients, in one patient both legs were operated upon. In 39 patients this kind of bypass was needed in only one lower extremity. Thirty patients were diabetic (75%). All patients suffered from rest pain and/or gangrene, with a major amputation as the only alternative (Table 1). In all but 6 legs, preceding attempts at conservative treatment, PTA or local treatment had failed to heal the lesions and save the foot. In eighteen patients (44%) a recurrence of symptoms after a previous reconstruction in the same leg was seen. Routine angiological examination consisted of pulse palpation and measurement of the ankle-brachial pressure index (A/B I). Routine translumbar or retrograde Seldinger aortography was usually insufficient to visualise the lower leg arteries adequately. Therefore additional biplanar angiograms were obtained after direct femoral puncture. All lesions of the foot or lower leg were documented photographically°

*Engineer for Informationin Medicine Please address reprint requests to: Dennis P, van Berge Hengouwen, Klinik Oberwald, Postfach 1149, 6424 Grebenhain-l, West Germany 0950-821X/87/040251+08503.00/0

© 1987 Grune &Stratton Ltd

252

D.P. van Berge Henegouwen

Table 2. Type of bypass

Table 1. Patients data Patients (16 female, 24 male)

40

Legs

41

m Age (48-87 years)

67.9

Diabetes mellitus

30 ( 75%)

Restpain

3

Restpain with gangrene

38

Recurrence after prey. recon.

18 (44%)

Preoperative Ankle-Brachial I.

0.28

Proximal

Distal

CFA

dist. tib.

2

SFA

dist. tib.

7

Pop. above knee

dist. tib.

2

Pop. below knee

dist. tib.

6

CFA

pedal

2

SFA

pedal

5

Pop. above knee

pedal

3

Pop. below knee

pedal

14

Total

n

41

(CFA: Common Femoral A., SFA:Superficial Femoral A., Pop: Popliteal A.)

Methods

Fig. l. Schematic view of the distal anastomosis with AVP; A: recipient artery, V: concomitant vein, B: bypass. Eur I Vasc Surg Vol ], August 1987

Most p a t i e n t s were o p e r a t e d u p o n u n d e r p e r i d u r a l a n a e s thesia. The p e r i d u r a l c a t h e t e r w a s left in place for at least t h r e e days. During t h e o p e r a t i o n the patients were antic o a g u l a t e d using 2 5 0 0 - 5 0 0 0 IU of i n t r a v e n o u s Heparin. All p a t i e n t s w i t h g a n g r e n e or i s c h a e m i c ulcers were given antibiotic p r o p h y l a x i s for 2 4 h using 3 x 8 0 mg G e n t a m i c i n a n d 3 x 10 mfllion,IU Penicillin i.v. starting one h o u r preoperatively. In cases w i t h cellulitis of the foot this r e g i m e was r a t i o n a l i s e d after microbiological tests a n d p r o l o n g e d as needed. A u t o l o g o u s vein w a s the preferred b y p a s s material. As a result the long s a p h e n o u s vein w a s dissected o u t in the l o w e r leg, leaving the p r o x i m a l p a r t in place w h e r e possible. I n some cases the s h o r t s a p h e n o u s vein or parts of t h e accessory s a p h e n o u s vein were used. In eight cases t w o or m o r e s e g m e n t s were j o i n e d t o g e t h e r to get the r e q u i r e d length. These veins were a l w a y s reversed before i m p l a n t a t i o n . During the o p e r a t i o n t h e vein was gently dilated a n d stored in h e p a r i n i s e d w h o l e blood. For short b y p a s s e s a m i n i m a l d i a m e t e r of 2.5 m m w a s accepted. In cases w h e r e a u t o l o g o u s vein w a s n o t available in the affected leg, h o m o l o g o u s long s a p h e n o u s vein was used. These veins w e r e h a r v e s t e d from stripped varicose veins a n d p r e p a r e d in 0.3% buffered m o n a l d e h y d e solution. The distal a n a s t o m o s i s was c o n s t r u c t e d first using 2,5 magnification. The recipient a r t e r y a n d t h e a d j a c e n t vein were p r e p a r e d a n d c l a m p e d w i t h fine silicone vessel loops or small bulldog clamps. W h e n t h e a r t e r y was obviously involved in severe disease, forceps were gently

Pedal Bypass

253

Fig. 2. Angiogram on the 10th post operative day following popliteo-pedalbypass with distal AVF, from the distal popliteal artery to the dorsalis pedis artery.

applied in the direction of the planned arteriotomy. The venotomy was limited to 5 m m and placed next to the proximal part of the arteriotomy. A simple side-to-side AVF was created by suturing the vein wall to the arterial wall. The graft was anastomosed to the AVF with a long patch reaching up to 15 m m distal of the fistula (Fig. 1). After completion of the anastomosis the graft was tunneled subcutaneously towards the proximal anastomosis. For a bypass to the dorsal pedal artery, the tunnel was made beneath the tendons of the tibialis anterior and extensor hallucis longus muscles. It was necessary to divide the superior extensor retinaculum in order to free these tendons anteriorly. The proximal anastomosis was sited as distally as possible, the only condition being a well functioning connection to the proximal arterial system. In the majority of cases the operation ended with extensive amputation of gangrenous ulcers or toes. Cellulitis of the foot was drained as deeply as possible. In some cases the distance between the distal anastomosis and the drainage wound was only 10 cm. Anticoagulation with heparin was replaced by coumarine beginning in the first postoperative week. All patients were mobilised during the first three days. If necessary further debridement was performed at the end of the first postoperative week. On approximately the

tenth postoperative day, all open bypasses were subjected to angiography. Since the introduction of new DSA equipment in January 19 8 5 flow and distribution studies were performed. 8 All lesions were repeatedly photographed in order to document, healing. After discharge from hospital patients were seen every 3 months. At each visit the pulse was palpated, A/B Index measured and auscultation and direct doppler sonography of the bypass and the AVF performed. Foot salvage and patency rates were calculated using the lifetable method as recommended by the Ad Hoc Committee on Reporting Standards appointed by the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery. 11

Results Preoperative angiograms showed occlusions at several levels. The most typical finding was the so called lower leg block (LLB); A relatively good proximal system with open femoral and popliteal arteries, whereas the trifurcation showed severe arteriosclerotic changes and aI1 three lower leg arteries showed occlusions at multiple levels. In the foot area the remnants of the posterior tibial and dot. EurJ Vasc Surg Vol 1, August 1987

254

D , P. van Berge H e n e g o u w e n

Table 4. Type of bypass versus failures Bypass

Amputation desp. patent,

n

Immediate occlusion*

Occlusion > 1 months

CFA Tib.

2

1

SFA Tib.

7

PaK Tib.

2

1

PbK Tib.

6

1

CFA Ped.

2

SPA Ped.

5

PaK Ped.

3

PbK Ped.

14

1

2 (1 amp.)

Total

41

4

9

1

(CFA:Common Femoral A., SFA:Superficial Femoral A., Pal(: Popliteal A. above knee, PbK: Popliteal A. below knee). * Secondary patency.

Fig. 3. Angiogram of a popliteal-pedal bypass, from the distal popliteal artery to the distal posterior tibial artery with distal AVF.

salis pedis arteries could often be seen.' In m o r e t h a n half of the cases this w a s t h e only a r e a w h e r e p a t e n t vessels were available. I n eleven legs t h e r e existed a LLB w i t h a complete or p a r t i a l occlusion of the popliteal artery. In three cases t h e r e existed a p a r t i a l occlusion of the superficial femoral a r t e r y a n d a LLB, leaving b e t w e e n t h e m a n

Table 3. Outflow and vessel wall quality at the distal anastomosis. (41 bypasses)

Occlusion of the plantar arch

25

Isolated segment

32

Diameter of the lumen < 1 mm Media-sclerosis Rock-like arteries Arteriosclerosis

8 19 10

Unspecific inflammatory changes

4

Thrombosis

1

EurJ Vasc Surg Vol 1, August 1987

isolated s e g m e n t of t h e popliteal artery. In 25 feet the deep p l a n t a r a r c h could n o t be visualised. In three p a t i e n t s the arterial tree was completely occluded from the g r o i n to the foot, l e a v i n g a n intense n e t w o r k of collaterals to feed t h e last o p e n a r t e r y at the level of the foot. In one p a t i e n t b o t h femoral a n d popliteal arteries were a n e u r y s m a l w i t h occlusion of the p r o x i m a l a n d mid lower leg arteries. The m e a n p r e o p e r a t i v e A/B I w a s 0 . 2 8 ( 0 . 1 - 0 . 5 5 ) . F o r t y - o n e bypasses were i m p l a n t e d in 4 0 patients. The types of bypass are s h o w n in Table 2. T w e n t y 4 o u r distal a n a s t o m o s e s were performed at or distal of t h e ankle joint (Figs 2 a n d 3). Six were a n a s t o m o s e d to the distal posterior tibial a r t e r y a n d eighteen to the dorsal pedal artery. S e v e n t e e n were placed b e t w e e n the ankle joint a n d a n i m a g i n e r y line 10 c m above t h e ankle joint. The p r o x i m a l a n a s t o m o s i s to the popliteal a r t e r y w a s above the k n e e on 25 occasions a n d b e l o w t h e knee o n 2 0 occasions. In t h i r t y one bypasses reversed a u t o l o g o u s vein a n d in t e n reversed h o m o l o g o u s vein w e r e used. The quality of the recipient arteries was p o o r (Table 3). T h i r t y - t w o bypasses w e r e a n a s t o m o s e d to isolated segm e n t s (78%) a n d eight recipient arteries h a d a l u m e n of less t h a n 1 m m at the time of the operation. In only seven arteries w a s the arterial wall n o r m a l . Most of t h e m a c r o scopic p a t h o l o g i c c h a n g e s were m e d i a l sclerosis (19) a n d small vessel arteriosclerosis (10). F o u r arteries s h o w e d n o n specific i n f l a m m a t o r y c h a n g e s a n d one h a d to be t h r o m b e c t o m i s e d . Nine patients suffered from cellulitis of the foot at the time of the operation. F o u r bypasses occluded rapidly a n d t h r o m b e c t o m y

Pedal Bypass

255

41 I00

T26

80

J " .........

20 j *6

60

18

15

6 . . 3 2

....

1 I0

9

6

5

2

E 40

20

I

I

J

I

I

i

I

3

6

9

12

15

I

I

18 21 Monfhs

I

I

P

1

l

24

27

30

33

36

Fig. 4. Life table analysis of the patency-rate. (Secondary patency - - ;

59

Primary patency

Table 5. Life table analysis secondary patency rate pedal bypasses No. withdrawn and reasons No. bypass at risk at start

No. of fail bypass

Duration

Loss to follow up/and*

Cumulat. patency

Death

Interval patency rate

0-1

41

3

0

0 + 2*

2

0.92

100

0

1-3

34

2

0

0 + 2*

0

0.94

92

4.4

3-6

30

1

0

0

0

0.97

86.4

5.8

6-9

29

1

2

0

0

0.96

83.8

6.3

9-12

26

2

3

0

0

0.92

80.5

6.9

12-15

21

2

0

0

0

0.90

74.4

8.2

15-18

19

0

2

0

1

1.00

66.9

8.8

18 21

16

1

4

0

0

0.93

66.9

9.6

21-24

11

0

1

0

0

1.00

62.3

11.5

24-27

10

0

1

0

3

1.00

62.3

12.0

27-30

6

0

3

0

0

1.00

62.3

15.6

30-33

3

0

1

0

0

1.00

62.3

22.0

33-36

2

0

1

0

0

1.00

62.3

27.0

Interval (mo)

(%)

Standard error

(%)

Pedal and distal lower leg bypasses; 40 patients; 41 bypasses. * Failure despite of an open bypass, see text. EttrJ Vasc Surg Vol 1, August 1987

O.P. van Berge Henegouwen

256

Table 6. Lifetable analysis primary patency rate pedal bypasses No. withdrawn and reasons No. bypass at risk at start

No. of fail. bypass

Duration

Loss to follow up/and*

0-1

41

4

0

1-3

33

2

3-6

29

6-9

L

Death

Interval patency rate

Cumulat. patency (%)

0 + 2*

2

0.90

100

0

0

0 + 2*

0

0.94

90

4.9

2

0

0

0

0.93

84.6

6.1

27

1

2

0

0

0.96

78.7

7.0

9-12

25

2

3

0

0

0.92

75.5

7.4

12-15

20

2

0

0

0

0.90

69.5

8.4

15-18

18

0

2

0

1

1.00

62.5

9.0

18-21

15

1

4

0

(/

0.92

62.5

9.9

21-24

10

0

1

0

0

1.00

57.5

1 1.8

24-27

9

0

1

0

2

1.00

57.5

12.5

27-30

6

0

3

0

0

1.00

57.5

15.3

30-33

3

0

1

0

0

1.00

57.5

21.6

33-36

2

0

1

0

0

1.00

57.5

26.6

Interval (mo)

Standard error (%)

Pedal and distal lower leg bypasses; 40 patients; 41 bypasses. *Failure despite of an open bypass, see text.

was o n l y successful in one. Two long bypasses from the groin to t h e foot a n d o n e b y p a s s from the p r o x i m a l superficial femoral a r t e r y to t h e foot t h r o m b o s e d again, so t h a t all t h r e e legs h a d to be a m p u t a t e d below the knee. In t h r e e o t h e r cases septic c o m p l i c a t i o n s of cellulitis in the foot could n o t be o v e r c o m e despite a n o p e n b y p a s s a n d good r e v a s c u l a r i s a t i o n . Deterioration of t h e patients g e n e r a l condition m a d e a n a m p u t a t i o n u n a v o i d a b l e . In the p a t i e n t w h e r e the recipient a r t e r y h a d to be t h r o m bectomised t h e foot did n o t i m p r o v e a n d p o s t o p e r a t i v e a n g i o g r a p h y s h o w e d t h a t outflow w a s exclusively t h r o u g h the v e n o u s limb of t h e AVF. In this case a n a m p u t a t i o n b e l o w t h e k n e e w a s necessary. N o n e of o u r patients r e q u i r e d a n a b o v e knee a m p u t a t i o n . Two patients died o n the t e n t h a n d 1 8 t h p o s t o p e r a t i v e d a y due to m y o c a r d i a l infarction. Both bypasses were p a t e n t a n d t h e feet were well revascularised. N o n e of the reconstructions b e c a m e infected. The m e a n p o s t o p e r a t i v e A/B I. for o p e n bypasses w a s 0.98. These pressures were m e a s u r e d over the distal arterial system. Figure 4 s h o w s t h e p a t e n c y r a t e w i t h a m e a n follow u p of 2 0 m o n t h s ( 1 4 0 m o n t h s ) , the foot salvage rate w a s 79% a n d the p a t e n c y rate 67% (Table 5, EurJ Vasc Surg Vol 1, August 1987

6 a n d 7). F o u r bypasses occluded w i t h i n 6 m o n t h s of surgery. Only t w o of these suffered a r e c u r r e n c e of g a n g r e n e . One r e q u i r e d below k n e e a m p u t a t i o n . In one case occlusion of the graft w a s c a u s e d by n e o - i n t i m a l hyperplasia, this b y p a s s w a s t h r o m b e c t o m i s e d a n d p a t c h e d . It t h e n ret h r o m b o s e d after h e a l i n g of the l a t e r a l foot a m p u t a t i o n w o u n d four m o n t h s later. After this, g a n g r e n e did n o t recur. Five o t h e r bypasses occluded after 9 to 2 0 m o n t h s a n d t h r e e patients r e m a i n e d in F o n t a i n e stage I or II. One occlusion w a s caused b y progression of arteriosclerosis in the aorto-iliac tract a n d a n iliac to deep femoral bypass r e s t o r e d a m a r g i n a l c i r c u l a t i o n just s h o r t of t h e rest p a i n stage. S h o r t bypasses t e n d e d to do better t h a n long ones (Table 4). Six of the n i n e h o m o l o g o u s vein bypasses e n d e d in immediate, e a r l y or late occlusion. All b u t one p a t i e n t n e e d e d extensive d e b r i d e m e n t n e c r o t o m i e s or a m p u t a t i o n s in the foot level. In the g r o u p of successful bypasses a total of 39 toe a n d five forefoot a m p u t a t i o n s h a d to be carried out. The AVF s h u n t i n g did n o t lead to a n y c a r d i a c p r o b l e m s in this series. A l t h o u g h m o s t legs exhibited p o s t r e c o n s t r u c t i v e oedema, this did n o t exceed the u s u a l o e d e m a found after b e l o w k n e e bypasses. D u r i n g follow u p five patients died of u n r e l a t e d

Pedal Bypass

257

Table 7. Litetable analysis foot salvage rate pedal bypasses No. withdrawn and reasons No. foot at risk at start

No. of amp.

Duration

Loss to follow up

Death

Interval foot salv. rate

0-1

41

5

0

0

2

0.875

1-3

34

2

0

0

0

0.94

87.5

5.3

3-6

32

1

0

0

1

0.97

82.3

6.2

6-9

30

0

2

0

0

1.00

79.3

6.6

9-12

28

0

3

0

0

1.00

79.3

6.8

12-15

25

0

0

0

0

1.00

79.3

7.2

15-18

25

0

4

0

1

1.00

79.3

7.2

18-21

20

0

4

0

1

1.00

79.3

8.1

21-24

15

0

1

0

0

1.00

79.3

9.4

24-27

14

0

1

0

3

1.00

79.3

9.7

27-30

10

0

4

0

0

1.00

79.3

11.5

30-33

6

0

1

0

0

1.00

79.3

14.8

33-36

5

0

2

0

0

1.00

79.3

16.3

Interval (mo)

Cumulat. foot salv. (%) 100

Standard error (%) 0

Pedal and distal lower leg bypasses; 40 patients; 41 bypasses.

causes. Two of t h e m had a n early occlusion w i t h o u t a r e c u r r e n c e of their gangrene. I n four cases the AVF occluded 6 to 18 m o n t h s postoperatively.

Discussion The presence of a good popliteal pulse a n d a n ischaemic foot d e m a n d s some form of arterial r e c o n s t r u c t i o n . On the other h a n d these patients are good candidates for below knee a m p u t a t i o n , w h i c h in c o m p a r i s o n to other kinds of m a j o r a m p u t a t i o n , do very well. M e n z o n i a n et al. d e m o n s t r a t e d t h a t the angiographic finding of a poor r u n off correlates very well with a high peripheral vascular resistance. 9 Especially in patients w h e r e the m a i n arterial occlusion is in the lower leg, the quality of the arterial bed is limited by the severity of disease affecting the most distal open arterial segments. Occlusion of the pedal arch is a bad o m e n for tibial bypasses, a n d is worse for pedal bypasses. 3 Nevertheless these isolated segments in the distal lower leg or foot offer the last hope for limb or foot salvage. The age a n d the general c o n d i t i o n of these patients are limiting factors for

good rehabilitation after a m p u t a t i o n m a k i n g limb salvage more desirable. Blaisdell et al. i n t r o d u c e d the a d j u n c t i v e AVF at the distal a n a s t o m o s i s in 1 9 6 6 ~ in order to increase flow in the graft a n d improve early a n d late p a t e n c y rates in cases with a poor run-off. Dardik a n d co-workers showed a difference i n limb salvage a n d p a t e n c y b e t w e e n poor r u n off bypasses with a n d w i t h o u t a n AVF. 3 The t e c h n i q u e for creating a n AVF differs b e t w e e n various authors. W h e r e a s Largiadair prefers a "bucket h a n d l e " AVF, others advise the c o m m o n o s t i u m technique.4, s Several studies h a v e s h o w n t h a t a n AVF at the distal anastomosis causes a two to threefold increase in flow in the graft. 3,4,s We constructed o u r bypass so t h a t the AVF occupied the proximal part of the anastomosis, because a flow of 2 0 0 - 4 0 0 m l / m i n causes a n i n t e n s e turbulence, we t h i n k it better to c o n s t r u c t the AVF in this fashion t h a n u s i n g a c o m m o n ostium.4 Flow studies u s i n g a DSA t e c h n i q u e 8 c o m p a r i n g several types of bypasses with or w i t h o u t a distal AVF in ten popliteal-pedal bypasses showed a m e a n flow of 2 58 m l / m i n . Distribution studies showed t h a t most of the arterial blood is lost into the AVF (88.2%). This gives a n inflow into the fore of approximately 4 0 m l / m i n w h i c h is EurJ Vasc Surg Vol 1, August 1987

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D.P. van Berge Henegouwen

in agreement with other studies. 2,3 It is interesting that neither we nor other authors saw a real steal phenomenon. Billet et al. showed that the loss of blood via the AVF depends on the diameter of the AVF and the existence of a proximal stenosis. 7 Although the primary patency rate in (90.2%) this series is m u c h higher t h a n would be expected for bypasses With such a bad outflow an AVF cannot always prevent immediate occlusion. These occlusions occurred in two long groin to foot and two shorter bypasses. It is assumed that the occlusions in the two extremely long bypasses were related to their length. Increasing the flow with the help of an AVF doesn't seem to keep long bypasses open. Veith et al. showed that short bypasses perform better than long ones. 6 In our small series very long bypasses tend to immediate or early occlusion. Although the foot salvage rate at twelve months is acceptable, some problems remain to be solved. Most disappointing were the amputations required despite a patent graft. A major threat to the revascularised foot is deep cellulitis. In this series six out of nine feet with this condition were saved by radical debridement and high dose antibiotic treatment, however even under normal conditions it can be extremely difficult to save a foot with a full-blown cellulitis. An encouraging finding was that permanent healing was possible even w h e n the bypass occluded after healing of the gangrene. In our opinion this confirms the marginal nature of the circulation in these patients. The collaterals originating from the popliteal artery prevent severe calf claudication and diabetic polyneuropathy causes a diminished sensation in the foot and often has a sympathectomy effect. Minor lesions don't heal but tend to become infected. Once this happens a vicious circle starts which can only be improved by immediate revascularisation and surgical drainage. After healing of the lesions bypass occlusion does not necessarily mean a recurrence of gangrene. 2 On the other hand the chances of healing without revascularisation are minimal.

Eur ] Vasc Surg Vol 1, August 1987

In conclusion: Pedal bypasses are a promising alternative for patients suffering from gangrene caused by occlusions in the lower leg arteries. Diabetics especially profit from this kind of bypass surgery. A simple side-to-side arteriovenous fistula enhances the otherwise low flow of these bypasses. On the other hand an AVF does not necessarily prevent immediate occlusion. Bypass occlusion after healing of the lesion does not necessarily lead to recurrence of the gangrene.

References 1 BLAISDELLFW, LIM RC, HALL AD, THOMAS AN. Reconstruction of small arteries with an arteriovenous fistula. An experimental study. ArchSurg 1 9 6 6 ; 9 2 : 1 1 6 - 1 2 1 . 2 BUCHBINDERD, PASCHAR, VERTAMJ, ROLLINSDL, RYAN TJ, SCHULER JJ, FLANIGANDP. Ankle bypass: Should we go the distance? Am J Surg 1985 ; 150:216-219. 3 DARDIKH, SUSSMANB, KAHN M, SVOBODAJJ, MENDES D, DARDIKI. Distal arteriovenous fistula as an adjunct to maintaining arterial and graft patency for limbsalvage. Surgery 1983;94: 478-486. 4 IBRAHIM IM, SUSSMANB, DAaDIK I, KAHN M, ISREAL M, KENNY M, DARmK H. Adjunctive arteriovenous fistula with tibial and peroneal reconstruction for limbsalvage. Am ] Surg 1980; 140: 246-251. 5 LArtCIADER J. Kruoro-pedale Rekunstruktionen bei peripherem arterMlem Querschnittverschluss im distalen Untersehenkel. VASA 1984;;13:24-31. 6 VEITHFJ, ASCERE, GUPTA SK, WHITE-FLORESS, SPRAYREGENS, SCHER LA, SAMSONRH. Tibiotibial vein bypass grafts: A new operation for limbsalvage. ] Vasc Surg 1985; 2 : 552-557. 7 BILLET A, QUERALLA, POLITO WF, DAGHER FJ. The vascular steal phenomenon: An experimental model. Surgery 1984; 96: 923-928. 8 STELZERG, VAN BERI;E HENEGOUWENDP. Flowestimation by DSA in bypasses with or without a distal arterio-venous fistula. Eur ] Vasc Surg 1987; 1:227-234. 9 MENZONIAN]O, LA MORTEWW, CANTELMONL, DOYLEJ, SmAWYAN,

SAVENORA. The preoperative angiogram as a predictor of peripheral vascular runoff. Am ] Surg 1985 ; 150:346-352. 10 REICHLE FA, TYSON RR. Comparison of long-term results of 364 femoropopliteal or femorotibial bypasses by revascularisation of severly ischemic lower extremities. Ann Surg 1975 ; 182 : 4 4 9 4 55. 11 Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery/North American Chapter, International Society for Cardiovascular Surgery. Suggested standards for reports dealing with lower extremity ischemia. ] Vasc Surg 1986; 4: 80-94.

Received 1 April 1987