Revascularization of the Ischemic Canine Hindlimb by Arteriovenous Reversal KAJ JOHANSEN, M.D., PH.D., EUGENE F. BERNSTEIN, M.D., PH.D.
Arteriovenous reversal (AVR) for revascularization of ischemic tissues has previously failed to meet theoretical, experimental, and clinical expectations despite recurrent trials. The efficacy of a new staged approach to AVR was tested against a canine ischemic limb preparation in which global ligation of ipsilateral collaterals inevitably led to limb gangrene. In 12 animals the complications of direct, single-stage end-to-end femoral AVR, inevitably accompanied by the development of extreme edema, were demonstrated. However, when the ischemic preparation was accompanied by a staged AVR, in which an initial end-artery-to-side-vein arteriovenous fistula was converted 1 week later to AVR by ligation of the central venous limb, 20 of 20 animals survived, and 19 of 20 were ambulatory long-term survivors with only mild edema. Serial angiograms at 1 week, 1 month, and 4 months demonstrated patency rates of 100, 84, and 63%, respectively. Histologic examination of animals electively killed from 4 to 24 months showed normal skeletal muscle histology, venous intimal thickening, and mild edema. In the acutely ischemic canine hind limb, a staged AVR can provide both viability and function with only mild edema formation. S TANDARD TECHNIQUES for arterial reconstruction are
generally of no avail when arterial occlusive disease is extensive and diffuse in its involvement of large and small arteries alike. In the extremities, such circumstances usually advance to tissue ischemia and gangrene. Despite multiple imaginative attempts at direct or collateral tissue revascularization, amputation usually has been the final therapeutic maneuver. For more than eight decades, attempts have been made to utilize an alternate, nondiseased pathway to the capillary bed-the venous tree. Arteriovenous reversal (AVR) of blood flow in the canine hindlimb was tested as a potential revascularization technique in the current study. Methods Several different studies were designed to discern whether AVR can perfuse tissues previously rendered Reprint requests to Kaj Johansen, M.D., Ph.D., Department of Surgery, University of Washington, Harborview Medical Center, Seattle, Washington. Submitted for publication: September 22, 1978.
From the Department of Surgery, University of California, San Diego, School of Medicine, La Jolla, California.
ischemic. This required the initial development of a control canine hind limb preparation in which irreversible tissue ischemia and gangrene were unavoidable without further intervention. Only by so doing could the effects seen with further manipulations properly be ascribed to the manipulation itself and not to the presence of collateral vessels. Clinical, physiologic, and pathologic criteria regarding tissue nutrition, flow distribution, and the effects of such reversed flow on both vessels and tissues were monitored serially. Fifty-six conditioned mongrel dogs were used for these experiments. Throughout, the precepts promulgated by the Committee on the Guide for Laboratory Animal Facilities and Care of the Institute of Laboratory Animal Resources of the National Academy of Sciences/National Research Council, as outlined in the Guide for Laboratory Animal Facilities and Care, were followed, and the animals' condition was monitored daily by licensed veterinarians of the Office of Animal Resources, UCSD School of Medicine. Group I. Control Ischemic Limb Preparation Twelve male and female mongrel dogs weighing 1525 kg were used to develop a reliable model for an ischemic limb that would undergo irreversible tissue death in the absence of a further therapeutic intervention. After an overnight fast, the animals were sedated with 2 cc intramuscular Innovar* and 0.5 mg atropine and then were anesthetized with 25 mg/kg intravenous pentobarbital,t further intravenous pentobarbital being administered incrementally during the course of the surgical procedure as needed. Heparin was administered (100 u/kg). Pitman-Moore, Washington Cro.ssing, New Jersey. t Diamond, Great Neck, New York.
*
0003-4932/79/0800/0243 $01.05 © J. B. Lippincott Company
243
244
JOHANSEN AND BERNSTEIN
CANINE LIMB ISCHEMIA PREPARATION Ao
Level of Vessel Anastomosis
FIG. 1. Scheme of collateral and peripheral femoral artery ligation that resulted in irreversible ischemia in the Group I animals.
In all animals the femoral artery was ligated and divided as far peripherally as possible in the adductor canal of one leg. More central arterial branches were also ligated and divided. Although initial attempts at limb devascularization were limited to denuding just the common femoral artery of its branches (up to the level of the inguinal ligament), inability to render the limb ischemic led to higher and higher ligations of branch arteries. Ultimately an irreversibly ischemic limb preparation was developed and applied in seven dogs (Group I) in which the following criteria were met: 1) The limb was functionless: the animal neither bore weight nor walked on the operated legs; and 2) the limb progressed to irreversible gangrene, or the animal died. To achieve these criteria, the final preparation (Fig. 1) involved ligature of the peripheral femoral artery and all femoral artery branches in the thigh, as well as ligature of the terminal aorta, both internal iliac arteries, the last ipsilateral lumbar artery,
Ann. Surg.
*
August 1979
and the ipsilateral deep circumflex iliac artery. The dogs were examined twice daily for evidence for limb viability, weight-bearing, and general clinical condition. A complete necropsy was performed on all animals, and specimens of skin and skeletal muscle were processed for microscopic examination. Group II. Immediate Arteriovenous Reversal Twelve mongrel dogs of both sexes, weighing 15-25 kg, underwent procedures combining limb devascularization as described for Group I with a surgical maneuver designed to provide immediate retrograde flow of arterial blood to the venous circulation of the limb. All animals were sedated and anesthetized as described previously. Heparin was administered (100 u/kg) and the femoral artery and the femoral vein were isolated in the adductor canal of the left leg. These vessels were divided, and the central arterial end and the peripheral venous end were anastomosed. In these animals, complete ipsilateral devascularization, as described in Group I animals, was performed as well. After the operations, daily examinations of limb viability were carried out. Doppler ultrasonographyt was utilized in several animals to investigate the peripheral progression of the arterial pulse velocity. Weight-bearing and exercise tolerance, skin temperature, wound healing, and palpable arterial pulsation were recorded daily for each animal, and limb circumference 10 cm above and 5 cm below the tibial tubercle was measured and recorded. The presence of subcutaneous hemorrhage and skin necrosis was gauged clinically and graded from 0 to 4+. Angiography was performed in one animal. Either electively or because of impending gangrene, all these animals were killed with 1 mg/kg of intravenous pentobarbital at periods of time up to six weeks after the operation, and necropsy examinations were performed.
Group III. Staged Arteriovenous Reversal Because one-stage AVR (Group II) had an unacceptably high mortality and morbidity, 32 animals were used to develop a technique of staged AVR adapted from a description by Hiertonn.8 Twenty animals comprise Group III. In the first stage the femoral artery was divided in the adductor canal and the peripheral end was ligated. An elliptical 6 mm defect was created in the lateral wall of the common femoral vein, and the artery was anastomosed end-toside to the vein. A 2-0 silk ligature, ends left long, was loosely passed twice around the central venous limb of this end-to-side arteriovenous fistula (AVF) * Medsonics, Mountain View, California.
VOl. 190.o NO. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
just above the area of anastomosis. Limb devascularization was performed as previously described, and the wound was closed with the long ends of the 2-0 silk suture left outside the fascia, beneath the skin closure. On postoperative day six or seven the wound was reopened under Innovar sedation (2 cc intramuscularly), the long ends of the 2-0 silk suture were located, and the central venous limb of the AVF was ligated, producing true AVR (Fig. 2). In eight Group III animals, electromagnetic flowmeter probes§ were used to measure flows in the femoral artery before and after AVF formation during the first stage, and immediately and seven days following ligation of the central venous limb of the AVF. Serial direct femoral puncture angiography was performed in all animals one to two and six to ten weeks after the second stage procedure. In addition, at 10-12 weeks after operation, seven animals underwent transcarotid catheter arteriography using a high-speed film changer (Westinghouse) and an automatic injector system." Patency of each of the AVRs was investigated, and collateral vessel formation was graded on sequential films from 0 to 4+ and tabulated. As before, the animals were examined daily for the first two weeks after the operation and then weekly thereafter, with tabulation of exercise tolerance, wound healing, skin temperature, and the presence of peripheral pulses as indicated by digital palpation and by Doppler ultrasonography. Limb circumference was carefully tabulated at points 10 cm above and 5 cm below the stifle ("knee"). The animals were serially killed at periods up to 24 months after operation. From selected animals, specimens of skin, muscle, and appropriate blood vessels were taken for pathologic examination. Results Group I. Control Ischemic Limb Preparation In Group I animals, in which a reproducible limb gangrene preparation was attempted, initial attempts demonstrated the remarkable proclivity of the dog to re-establish blood flow to an ischemic area by means of collaterals. However, in the last seven dogs in which complete devascularization was performed, the limbs were cold, tender, and functionless, and the animals never stood or bore weight. Angiography performed on one animal showed a thrombosed femoral artery and no sign of significant collateral ingrowth. All seven animals died or were killed in one to six days because of their clearly terminal state. Specimens of skin and muscle demonstrated early mild to moderate necrosis. § Statham, Hato Rey, Puerto Rico. ' Medrad, Allison Park, Pennsylvania.
245 TECHNIQUE OF FEMORAL AV REVERSAL
A
V
A
V
A
V
4"-
FIG. 2. Staged arteriovenous reversal, the Group III preparation, was accomplished by end-artery-to-side-vein fistula (left) and placement of loose suture around the proximal vein (center) in an initial sitting. A week later, the venous ligature was tightened (right) to complete the procedure.
Group II. Immediate Arteriovenous Reversal Group II animals underwent procedures designed to explore the utility of immediate AVR for limb salvage. These animals consistently developed almost immediate massive edema with average lower leg circumference rising from a control value of 18.67 + 0.5 cm to 28.71 + 1 cm on the third postoperative day (153.7% greater than control), peaking on day 9 at 32.35 + 1.5 cm (172.7% of control). The progression of edema formation with time in both the upper and lower leg is shown in Figure 3. In all cases the animal's limbs were cool and so swollen that usual anatomic land-
LEG EDEMA WITH AV FISTULA
45
30
30
25~2sm
35
20 3
E
0
I-0
.1-4
p'5
30 Control 2
4
6
8
10
12 14
TIME (Days) FIG. 3. Massive unrelenting limb edema followed fistula (Group II) operation.
simple AV
Ann. Surg. * August 1979
JOHANSEN AND BERNSTEIN
246
TABLE 1. Cumulative Data from Group II Dogs, Immediate AVR
Circumferences C/c* Dog No.
Day 0
Day I
Day 3
Day 7
Day 14
II-I
30/18 34/20 31/20 34/20 30/17 28/15 32/20 30/18 34/20 30/17 30/19 32/20
36/24 39/26 38/30 39/26 36/22
38/26 43/28 t 40/28 37/26
40/28 46/30
t
II-2 11-3 11-4 11-5 II-6 11-7 11-8 11-9 11-10 11-ll II-12
46/31 40/30
40/28 t 40/28 t 42/29 40/29
43/32
46/31 42/32 t 48/35
47/36
42/30
46/33
45/32
t 42/31
t
n
12
9
7
6
Mean C Mean c SEM SEM
31.25 18.67
38.89 26.89
40.71 28.71
44.67 31.50
4 44.50 32.35
0.59 0.50
0.69 0.92
0.99 0.96
1.34 1.08
1.38 1.52
t
* C, 10 cm above tibial tubercle; c, 5 cm below tibial tubercle. t Animal found dead, or killed. t Arteriovenous reversals patent at necropsy.
.
; _ ii.
Stand/Weight Bearing (Day) Never 2 days Never 3 days, 2 days, 0 8 days, 0 6 days, 0 0 0
living living
living living
Skin Necrosis
Hemorrhage
+++ +++
++ ++ +++ + ++
0 0 0 ++ 0 0 0 0 ++ +++
++++ ++ + ++ ++ +++ ++++
Time of Death (killing) 8 days 9 days (3 days)t (5 wk) (6 wk)§ 7 days (5 wk) I day: (3 wk)
Iday 3 dayst (5 days)
§ Animal found to have thrombosed AVR, profuse collateral vessel formation on immediate postmortem arteriogram.
marks were effaced, wound healing was poor, and the limbs were minimally functional, even in the longterm survivors. The animals frequently manifested significant subcutaneous hemorrhage and skin necrosis, as noted in Table 1. Doppler ultrasonography failed to reveal a pulse peripheral to the site of anastomosis after the third postoperative day in any animal. The animals generally declined to bear weight on the operated leg, and apparent sepsis appeared to supervene in several cases. Eight of the 12 animals died or were put to death within two weeks. Necropsy showed massive edema and nonviable muscle, and muscle necrosis was demonstrable by microscopy. Four animals survived: edema subsided slightly, but neither limb circumference nor function returned to normal, though these animals bore weight with a limp. Angiography performed on one of these animals showed profuse collateral development and thrombosis of the AV communication (Fig. 4). Of the 12 animals, only 3 had patent AV anastomoses at the time of necropsy.
Group III. Staged Arteriovenous Reversal
F IG. 4. Angiography in a Group II dog. Femoral artery (FA) inDction (A) shows obliteration of main channel of venous tree, but ich collateral formation peripherally (B) with FA reconstitution.
Group III animals underwent procedures designed to explore the use of a staged AVR preparation for limb salvage; formation of an initial arteriovenous fistula (AVF) was followed in 1 week by ligation of the central venous limb of the AVF, thereby creating a "delayed AVR. Limb devascularization was per formed at the first sitting. All 20 animals survived
VOl. 190.9 NO. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
operation and 19 were long-term survivors. One animal was found dead in his cage 1 week after the second operation; he had previously seemed healthy and had walked without difficulty on his operated leg. Necropsy failed to reveal a cause for death. The AV anastomosis was intact and patent, and skin and skeletal muscle seemed viable. Minimal edema was present, with the limb circumference of the operated leg 4% greater than control. Microscopic examination of tissue was not done. All Group III animals stood shortly after AVF formation, but only 6/20 bore weight normally; all manifested evidence for ongoing discomfort in the limb, attempting to avoid manipulation or examination. Wound healing was excellent and occurred per primam. After conversion to AVR, all animals stood within 12 hours and 16/20 bore weight on the reoperated limb within that period: within 1 week all animals walked without obvious limb dysfunction. This general clinical impression of normal function was maintained indefinitely thereafter. All animals manifested mild edema after AVF formation, with initial lower limb circumference of 18.65 ± 0.2 cm rising to 20.05 ± 0.4 on day 3 (107.5% of control), 21.75 ± 0.5 cm at the time of AVR conversion (116.6% of control), and peaking at 21.94 ± 0.4 cm (117.6% of control) at one week after initiation of reversed flow. At six weeks after AVR lower limb circumference had fallen to 20.29 ± 0.9 cm (108.8% of control) (Fig. 5). Doppler ultrasonography documented femoral arterial flow through the venous anastomosis in each of six animals studied at the level of the stifle 3 weeks after
247
FIG. 6. Multiple subcutaneous vascular collaterals are easily visible in a Group III dog several months after AV reversal.
FIG. 5. With staged AV reversal (Group III), leg edema was modest and reversed within several weeks following second stage of
surgery. In two animals an arterial pulse could be palpated manually in a dilated peripheral vein well beyond the stifle. Multiple large vascular collaterals developed subcutaneously (Fig. 6). Four months after surgery three animals were re-examined, and all were found to have a positive Doppler signal in the peripheral limb; one had a palpable pulse 15 cm below the level of AVR. The presence of Doppler signals in operated animals is recorded in Table 2. Angiograms were performed at several times after operation. Examined serially, these demonstrate increasing arterial collateral ingrowth and, in several cases, persistent retrograde venous flow to the level of the ankle (Fig. 7). Graded collateral vessel formation is presented in Table 2. So far as could be determined, 14/19 animals had patent AV communications at 1 month, and 6/7 selected animals demonstrated angiographic patency at ten weeks after operation. No functional difference could be discerned between animals with and without patent AV
operation.
anastomoses.
LEG EDEMA WITH AV REVERSAL
E
32
C.)
I-
31
L.I Control
3 O8
1
I
I
7
14
21
28
-818
-
35
42
TIME (Days)
248
Ann. Surg.
JOHANSEN AND BERNSTEIN TABLE 2. Cumltulaitiv e Datal for Gr-ouip HI Dog.s,
Circumferences C/c*
Stagedl A VR
Doppler Pulses
AVR Patency by Angio.
Dog No.
Day 0
Day 3
Day 7
Day 14
Day 28
Day 42
111-1 111-2 111-3 I11-4 111-5 111-6 111-7 111-8 111-9 111-10 111-11 111-12 111-13 111-14 111-15 111-16 111-17 111-18 111-19 111-20
30/18 34/20 32/20 30/17 28/15 30/19 30/20 29/17 30/20 28/18 30/18 34/20 28/15 30/20 34/20 30/18 32/19 35/21 30/18 34/20
32/20 36/22 33/22 32/20 29/16 31/19 32/22 30/18 31/20 28/19 30/19 35/21
32/22 37/24 34/24 32/21 29/19 30/21 32/23 30/20 31/22 (29/20) 31/22 37/23
30/21
30/21
+
-
+ 0
31/21 35/21 30/18 34/20 35/22 30/20 34/21
33/21 38/25 35/25 32/2 1 29/19 31/22 32/24 30/21 31/23 29/20 31/22 37/22 29/16 31/23 34/22 30/19 34/22 35/24 31/21 35/23
Mean C Mean c
30.90 18.65
32.00 20.05
32.35 21.75
SEM SEM
0.51 0.23
0.54 0.38
n
20
19
C. 10
cm
above stifle,
-
c,
5
cm
32/23 32/21 29/19
3 Wk
32/23 32/20
32/22 29/30 -30/22 35/22
3 1/22 35/23 31/20 34/21
31/21 34/23
31/22 35/24 32.47
30/20
+ +
-
+
-
+
30/16
+
33/22
+ -
33/21
31.29 20.29
0.61 0.50
0.59 0.36
0.58 0.37
0.45 0.90
20
17
12
7
+
-
++ ++
0
+++ + 4++++
+
+
++
+ 0 +
+
++ +++
+ +
+
+ + +
+ +
+ ++ ++ + ++
-+
0 -
+
+
-
0 + +
-++
-
31/20
31.50 21.25
Collaterals (O to ++++)
10 Wk
0 + +
31/20
21.44
4 Wk
+
-
-
below stifle.
16 Wk
-
-
June 1979
Animal found dead in
++++ ++ +++
+
cage: no cause
for death found at
necropsy.
FIG.
Group One
weecs. collateral
period.
Angiography dogs. (b,
(a,
right)
left)
Vol. 190 -No. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
249
FIG. 7 c and d. Multiple films demonstrated persistent flow to level of the ankle.
I FIG. 7 e and f. Midstream aortograms demonstrate, by comparison with the non-
operated left hindlimb, the massive increase in collateral vessels in both arterial and venous phases of the
injections.
Electromagnetic flow determinations before and after the time of AVF formation, before and after AVR conversion, and one week after initiation of AVR in seven animals showed that initial (baseline) femoral artery flow was augmented by AVF formation, as expected. Initial moderate flows with AVR (87.2 ± 24.2 cc/min) rose to flows to 126.7 + 48.3 cc/min
one week later, as demonstrated in Figure 8 and Table 3. Necropsy examinations showed no sign of cardiac chamber or wall hypertrophy; the pertinent vessels showed some evidence for thinning and tortuosity in the artery, while examination of the vein showed thickening of the intima and media with some fibrosis
Ann. Surg. * August 1979
JOHANSEN AND BERNSTEIN
250
FEMORAL ARTERY FLOW WITH AV I2CV=DQA mv nr-c wnopRLI
There has been
no
shortage of innovative attempts
to salvage ischemic extremities in circumstances in
c
which standard revascularization procedures (end-
E
arterectomy, bypass grafting, sympathectomy) have
200 F
failed. Direct muscle revascularization,14 implantation of Ivalon sponge cubes into which the superior epigastric artery was inserted,4 connection of the arterialized in situ saphenous vein into the medullary cavity of the femur,16 and subcutaneous transfer of omental pedicle grafts3 are among the more creative trials undertaken either in experimental animals or in patients.
0
-J
Discussion
100
F
U-
Control
AVF +
AVF 1 wk
AVR
AVR
+ 1 wk
FIG. 8. Flow through femoral artery reaches a peak following AV fistula construction and decreases to contirol levels following proximal venous ligation and conversion of AV fis ,tulatoAVreversal,
That increased blood flow and intense collateral
vessel formation occurs around an arteriovenous communication, either congenital or acquired, has led occasional investigators to explore the use of the AVF for tissue revascularization. Experimental studies in
dogs by Root and Cruz'2 and in turkeys by Matolo et al.11 suggested that an AVF can cause, both by retro-
(Fig. 9a). Serial excrescences in the v ein were felt to represent thrombosed valves (Fig. 9b). No abnormalities were noted upon microscopic exajmination of the skin or muscle. One dog was kept for 24 months a Lfter operation. Clinically the animal did well, without e vidence for disability or exercise intolerance. The arnimal was then anesthetized and underwent angiograph y by techniques described previously. The angiogram (Fig. 10) shows thrombosis of the main AVR channiel but profuse collateral flow through serpiginous paralIlel vessels. The animal was killed and multiple sections of vessels were taken for microscopic examination. Ais before, they demonstrated thrombosis of the valves and arterialization of the veins, with intimal and medial hypertrophy. The AV anastomosis showed an .intimal ingrowth which had rendered it stenotic (2 mm) but not occluded. In summary, heroic denuding of actu,al and potential collateral sources, both ipsilaterally and contralaterally, ultimately led to a canine surgical prepaLration that provided reproducible, irreversible limb ischemia and gangrene in seven animals (Group I). then immediate end-to-end femoral AVR was added tio this preparation (Group II), massive incapacitatirig limb edema resulted, accompanied by incontrove rtible signs of poor tissue perfusion and sepsis. Howe ver, when limb devascularization was accompanied b)y a side-to-side AVF, converted one week later to tru e AVR (Group III), all animals survived the procedure and 19/20 were electively killed up to 24 months lateDr. None demonstrated significant limb edema and s,everal clinical, physiologic, and angiographic meast ires suggested that adequate tissue perfusion was prov rided by AVR.
grade venous flow and by intense arterial pollateralization, perfusion sufficient to nourish an extremity. Pilot clinical studies between 1965 and 1970 by groups in San Francisco and Honolulu implied occasional successes in ameliorating limb ischemia, but these have not been confirmed subsequently. Similar studies with arteriovenous fistulas, without reversal, have also been recently reported from our laboratory.5'6 In these experiments, AV fistula alone offered no protective physiologic benefit against a severe limb ischemia model, in marked contrast to the dramatic benefits to limb perfusion and tissue nutrition which followed the construction of an anastomosis with an AV reversal component. For this reason, and because of the relatively large literature confirming the absence of significant protection from acute ischemia associated with simple AV fistula construction, no "control" group of AV fistula animals was included in the current experimental series. TABLE 3. Electromagnetic Flow Data for Group III Dogs, Staged AVR
Electromagnetic Flow (ml/min)
Dog No.
Control
AVF
III-25 111-26 III-27 III-28 III-29 III-30 III-31 Mean flow SEM
68 52 112 75 98 66 48 74.1 9.5
62 88 162 88 148 90 98 105.1 14.7
AVF + 1 Wk
160 225 420 180 205 165 225.8 43.9
AVR AVR 38 60 180 80 45 120 87.2 24.2
+ I Wk
95 205 80 126.7 48.3
Vol. 190.o NO. 2
FIG. 9a and b. (a) Representative section of vein through which reversed ar-E terial flow has passed 24 ' months in a Group III dog. The intima and media are Tangential section of venous valve in a 24-monthold Group III dog. The valve was markedly shortened and thickened and on gross examination of the vessel surface, the valve was clearly incompetent against reversed flow.
~
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
251
I-
Flow reversal, perhaps the most radical revascularization concept of all, is also the oldest, predating the beginnings of vascular surgery. The concept was attempted experimentally in 1881, and the first clinical
attempt, by the Spanish surgeon, San Martin y Satrustegui, occurred in 1902.13 Occasional successes engendered enough enthusiasm that widespread clinical trials were carried out prior to 1920. Ultimately,
252
JOHANSEN AND BERNSTEIN
Ann. Surg. * August 1979
FIG. 10. Angiogram of Group III dog 24 months after AVR. A, site of femoral artery injection; B, site of AV anastomosis; C, massive venous collaterals; D, site of ongoing retrograde venous flow; E, new arterial collaterals.
however, the physiologic inconsistency of the theory and its poor results in practice were responsible for discarding the concept. Spurred by the success of new attacks on congenital cardiac defects, Beck2 developed several procedures involving retrograde perfusion of the myocardium via the cardiac veins in patients with coronary artery insufficiency. His coworkers10 attempted to revascularize the cerebral circulation of patients suffering from cerebral palsy, mental retardation, or epilepsy by anastomosing the carotid artery to the jugular vein. At about the same time, Johnston et al.9 reported good to excellent results in each of nine patients with threatened limb gangrene on whom they performed end-to-end femoral triangle AVR. However, in a careful clinical study of such centrally located AVRs. Szilagyi et al. 15 demonstrated rapid stepwise loss of the pressure head due to the succession of venous valves. Alternative bypass and endarterectomy techniques were developed, and vascular surgeons again lost interest in AVR. More recently, Root and Cruz12 demonstrated that tissue perfusion can be supplied by AVR in dogs. Those investigators, as well as Amir-Jahed' and Matolo et al.," further showed that immediate end-to-end AVR is inevitably followed by a massive transudation of fluid and edema formation. Though his attempts were directed toward the amelioration of leg-length dis-
crepancy rather than tissue revascularization, Hiertonn8 demonstrated that formation first of an AVF, followed later by ligation of the central venous limb to yield a true AVR, provided an excellent result, with augmented leg length development and the absence of excessive edema formation. His experiments formed the basis of our two-staged approach. It is extraordinarily difficult to produce limb gangrene in the dog, whose propensity to develop a new and major collateral supply from tiny remote arterial twigs is well recognized. Since the current investigation was designed to ascertain whether arterial flow retrograde in the veins would keep tissues alive, an extreme control preparation was required, i.e., a limb with no other nutritional blood supply that inevitably would undergo ischemic necrosis without a further, successful, therapeutic maneuver. That the current Group I model is a satisfactory "ischemic limb" preparation is supported not only by this study's results, but also by comparison with the essentially identical Group I dogs of Root and Cruz'2 and Group I turkeys of Matolo et al."l The simplest AVR (end-to-end connection offemoral artery and vein) caused severe limb edema and death in two-thirds of the animals. Thrombosis of the AVR was frequently demonstrable, in association with lethal limb gangrene. The staged AVR preparation, in which an initial side-to-side arteriovenous fistula was con-
Vol. 190 * No. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
verted to AVR by ligation of the central venous limb, was very acceptable. Limb edema was not a prominent feature, and other clinical and quantitative criteria suggested that these devascularized limbs now had an adequate blood supply. A number of "physiologic fallacies" have been presented as evidence against the usefulness of AVR in limb revascularization: 1) The flow must traverse competent venous valves. However, in situ saphenous vein femoralpopliteal grafts conduct similarly reversed flow following valve destruction. 2) Centripetal venous tributaries might shunt blood to the superficial venous system and decompress the inflow arterial pressure head, to the extent that little or no perfusion of the distal microcirculation would occur. However, the success of the Group III preparation speaks against this concern. Further, ligation of perforating veins connecting the deep and superficial venous systems could block such shunting, if necessary. 3) Can arterial blood presented retrograde to the terminal circulation carry out normal cellular nutrition and clearance of metabolites? Microvascular work by Zweifach17 using vital dyes suggests that exchange of small molecules can occur with such reverse perfusion, and Heimbecker et al.7 demonstrated oxygen uptake across a retroperfused capillary bed. 4) If the venous tree is used as inflow, what will serve as the venous outflow? In our preparation, the superficial venous tree is used as an inflow route. It is likely that new deep venous collaterals rapidly form and/or enlarge, as demonstrated by the Group III animals with ongoing arterial inflow (Fig. 8) in the absence of excessive edema formation (Fig. 5).
253
in the management of severe peripheral ischemia. The current study suggests that the excessive edema formation that occurs with immediate end-to-end AVR can be avoided by forming an initial end-artery-to-sidevein AVF, with later ligation of the central venous limb to cause AVR. Nineteen of 20 dogs enjoyed longterm survival with such a preparation. Several theoretical fallacies exist, asserting that AVR cannot perform retrograde perfusion of the terminal circulation. These issues can be only partially answered from the published reports and are under active investigation in our laboratory. References 1. Amir-Jahed, A. K.: Revascularization of Lower Extremities by Reversal of Blood Flow with and without Lumbar Sympathectomy: An Experimental Study. Surgery, 59:243, 1966. 2. Beck, C. S.: Surgical Operations for Coronary Artery Disease. In Encyclopedia of Thoracic Surgery, Vol. II. Berlin, Springer-Verlag, 1959, p. 779. 3. Casten, D. F. and Alday, E. S.: Omental Transfer for Revascularization of the Extremities. Surg. Gynecol. Obstet., 126:301, 1971. 4. Friedman, E. W., Lambert, P. B. and Frank, H. A.: Vascular Connections Established by Arteries Implanted into the Lower Extremity with Plastic Sponge as an Intermediary. Surgery, 60:386, 1966. 5. Gausewitz, S., Gerard, D. F., Dilley, R. B. and Bernstein, E. F.: Arteriovenous Anastomosis (AVA) and Arteriovenous Fistula (AVF) in Revascularizing the Ischemic Canine Hindlimb. Surg. Forum, 29:211, 1978. 6. Gerard, D. F., Dilley, R. B. and Bernstein, E. F.: The Acute Physiologic Effects of an Arteriovenous Anastomosis in the Devascularized Canine Hindlimb. Surg. Forum, 28:206, 1977. 7. Heimbecker, P., Vivien, T. and Blalock, A.: Experimental Reversal of Capillary Flow. Circulation 4:116, 1951. 8. Hiertonn, T.: Arteriovenous Fistula for Discrepancy in Length of Lower Extremities. Acta Orthop. Scand., 31:25, 1961. 9. Johnston, C. G., Jordan, P. and Cloud, T.: Arteriovenous Anastomosis in Traumatic Vascular Lesions. Ann. J. Surg.,
80:809, 1950. 10. McKhann, C. F., Belknap, W. D. and Beck, C. S.: Cervical Arteriovenous Anastomosis in Treatment of Mental Retardation, Convulsive Disorders, and Cerebral Spasticity.
Ann. Surg., 132:162, 1950.
The current experimental thus has provided 1) a reproducible canine model for limb ischemia, 2) proof of unacceptably massive edema formation with immediate end-to-end AVR, and 3) evidence that conversion of an initial AVF into an AVR in a limb previously made irreversibly ischemic appears to salvage the limb without excessive edema formation. The concept of staged venous flow reversal therefore appears worthy of further investigation as an approach to the severely ischemic extremity. Summary Reversal of the circulation arises phoenix-like from the ashes of authoritative assertions of its inutility
11. Matolo, N. M., Cohen, S. W. and Wolfman, E. F.: Use of an Arteriovenous Fistula for Treatment of Severely Ischemic Extremity: Experimental Evaluation. Ann. Surg., 184:622,
1976. 12. Root, H. D. and Cruz, A. B., Jr.: Effects of an Arteriovenous Fistula on the Devascularized Limb. JAMA, 191:109, 1965. 13. San Martin y Satrustegui, A.: Chirurgie de l'appareil Circulatoire: l'anastomose Arterio-veineuse. Sem. Med., p. 395, 1902. 14. Shionoya, S., Ban, I. and Nakata, Y.: Skeletal Muscle Revascularization by Vascular Implantation. J. Cardiovasc. Surg., 14:208, 1973. 15. Szilagyi, D., Jay, G. D. and Munnell, E. D.: Femoral Arteriovenous Anastomosis in the Treatment of Occlusive Arterial Disease. Arch. Surg., 63:435, 1951. 16. Vetto, R. M. and Belzer, F. O.: Use of an Arterio-bone Fistula in Advanced Ischemia. Surg. Forum, 16:131, 1965. 17. Zweifach, B. W.: The Structural Basis of Permeability and Other Functions of Blood Capillaries. Cold Spring Harbor Symposia on Quantitative Biology, 18:216, 1940.
Arteriovenous reversal (AVR) for revascularization of ischemic tissues has previously failed to meet theoretical, experimental, and clinical expectations despite recurrent trials. The efficacy of a new staged approach to AVR was tested against a canine ischemic limb preparation in which global ligation of ipsilateral collaterals inevitably led to limb gangrene. In 12 animals the complications of direct, single-stage end-to-end femoral AVR, inevitably accompanied by the development of extreme edema, were demonstrated. However, when the ischemic preparation was accompanied by a staged AVR, in which an initial end-artery-to-side-vein arteriovenous fistula was converted 1 week later to AVR by ligation of the central venous limb, 20 of 20 animals survived, and 19 of 20 were ambulatory long-term survivors with only mild edema. Serial angiograms at 1 week, 1 month, and 4 months demonstrated patency rates of 100, 84, and 63%, respectively. Histologic examination of animals electively killed from 4 to 24 months showed normal skeletal muscle histology, venous intimal thickening, and mild edema. In the acutely ischemic canine hind limb, a staged AVR can provide both viability and function with only mild edema formation. S TANDARD TECHNIQUES for arterial reconstruction are
generally of no avail when arterial occlusive disease is extensive and diffuse in its involvement of large and small arteries alike. In the extremities, such circumstances usually advance to tissue ischemia and gangrene. Despite multiple imaginative attempts at direct or collateral tissue revascularization, amputation usually has been the final therapeutic maneuver. For more than eight decades, attempts have been made to utilize an alternate, nondiseased pathway to the capillary bed-the venous tree. Arteriovenous reversal (AVR) of blood flow in the canine hindlimb was tested as a potential revascularization technique in the current study. Methods Several different studies were designed to discern whether AVR can perfuse tissues previously rendered Reprint requests to Kaj Johansen, M.D., Ph.D., Department of Surgery, University of Washington, Harborview Medical Center, Seattle, Washington. Submitted for publication: September 22, 1978.
From the Department of Surgery, University of California, San Diego, School of Medicine, La Jolla, California.
ischemic. This required the initial development of a control canine hind limb preparation in which irreversible tissue ischemia and gangrene were unavoidable without further intervention. Only by so doing could the effects seen with further manipulations properly be ascribed to the manipulation itself and not to the presence of collateral vessels. Clinical, physiologic, and pathologic criteria regarding tissue nutrition, flow distribution, and the effects of such reversed flow on both vessels and tissues were monitored serially. Fifty-six conditioned mongrel dogs were used for these experiments. Throughout, the precepts promulgated by the Committee on the Guide for Laboratory Animal Facilities and Care of the Institute of Laboratory Animal Resources of the National Academy of Sciences/National Research Council, as outlined in the Guide for Laboratory Animal Facilities and Care, were followed, and the animals' condition was monitored daily by licensed veterinarians of the Office of Animal Resources, UCSD School of Medicine. Group I. Control Ischemic Limb Preparation Twelve male and female mongrel dogs weighing 1525 kg were used to develop a reliable model for an ischemic limb that would undergo irreversible tissue death in the absence of a further therapeutic intervention. After an overnight fast, the animals were sedated with 2 cc intramuscular Innovar* and 0.5 mg atropine and then were anesthetized with 25 mg/kg intravenous pentobarbital,t further intravenous pentobarbital being administered incrementally during the course of the surgical procedure as needed. Heparin was administered (100 u/kg). Pitman-Moore, Washington Cro.ssing, New Jersey. t Diamond, Great Neck, New York.
*
0003-4932/79/0800/0243 $01.05 © J. B. Lippincott Company
243
244
JOHANSEN AND BERNSTEIN
CANINE LIMB ISCHEMIA PREPARATION Ao
Level of Vessel Anastomosis
FIG. 1. Scheme of collateral and peripheral femoral artery ligation that resulted in irreversible ischemia in the Group I animals.
In all animals the femoral artery was ligated and divided as far peripherally as possible in the adductor canal of one leg. More central arterial branches were also ligated and divided. Although initial attempts at limb devascularization were limited to denuding just the common femoral artery of its branches (up to the level of the inguinal ligament), inability to render the limb ischemic led to higher and higher ligations of branch arteries. Ultimately an irreversibly ischemic limb preparation was developed and applied in seven dogs (Group I) in which the following criteria were met: 1) The limb was functionless: the animal neither bore weight nor walked on the operated legs; and 2) the limb progressed to irreversible gangrene, or the animal died. To achieve these criteria, the final preparation (Fig. 1) involved ligature of the peripheral femoral artery and all femoral artery branches in the thigh, as well as ligature of the terminal aorta, both internal iliac arteries, the last ipsilateral lumbar artery,
Ann. Surg.
*
August 1979
and the ipsilateral deep circumflex iliac artery. The dogs were examined twice daily for evidence for limb viability, weight-bearing, and general clinical condition. A complete necropsy was performed on all animals, and specimens of skin and skeletal muscle were processed for microscopic examination. Group II. Immediate Arteriovenous Reversal Twelve mongrel dogs of both sexes, weighing 15-25 kg, underwent procedures combining limb devascularization as described for Group I with a surgical maneuver designed to provide immediate retrograde flow of arterial blood to the venous circulation of the limb. All animals were sedated and anesthetized as described previously. Heparin was administered (100 u/kg) and the femoral artery and the femoral vein were isolated in the adductor canal of the left leg. These vessels were divided, and the central arterial end and the peripheral venous end were anastomosed. In these animals, complete ipsilateral devascularization, as described in Group I animals, was performed as well. After the operations, daily examinations of limb viability were carried out. Doppler ultrasonographyt was utilized in several animals to investigate the peripheral progression of the arterial pulse velocity. Weight-bearing and exercise tolerance, skin temperature, wound healing, and palpable arterial pulsation were recorded daily for each animal, and limb circumference 10 cm above and 5 cm below the tibial tubercle was measured and recorded. The presence of subcutaneous hemorrhage and skin necrosis was gauged clinically and graded from 0 to 4+. Angiography was performed in one animal. Either electively or because of impending gangrene, all these animals were killed with 1 mg/kg of intravenous pentobarbital at periods of time up to six weeks after the operation, and necropsy examinations were performed.
Group III. Staged Arteriovenous Reversal Because one-stage AVR (Group II) had an unacceptably high mortality and morbidity, 32 animals were used to develop a technique of staged AVR adapted from a description by Hiertonn.8 Twenty animals comprise Group III. In the first stage the femoral artery was divided in the adductor canal and the peripheral end was ligated. An elliptical 6 mm defect was created in the lateral wall of the common femoral vein, and the artery was anastomosed end-toside to the vein. A 2-0 silk ligature, ends left long, was loosely passed twice around the central venous limb of this end-to-side arteriovenous fistula (AVF) * Medsonics, Mountain View, California.
VOl. 190.o NO. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
just above the area of anastomosis. Limb devascularization was performed as previously described, and the wound was closed with the long ends of the 2-0 silk suture left outside the fascia, beneath the skin closure. On postoperative day six or seven the wound was reopened under Innovar sedation (2 cc intramuscularly), the long ends of the 2-0 silk suture were located, and the central venous limb of the AVF was ligated, producing true AVR (Fig. 2). In eight Group III animals, electromagnetic flowmeter probes§ were used to measure flows in the femoral artery before and after AVF formation during the first stage, and immediately and seven days following ligation of the central venous limb of the AVF. Serial direct femoral puncture angiography was performed in all animals one to two and six to ten weeks after the second stage procedure. In addition, at 10-12 weeks after operation, seven animals underwent transcarotid catheter arteriography using a high-speed film changer (Westinghouse) and an automatic injector system." Patency of each of the AVRs was investigated, and collateral vessel formation was graded on sequential films from 0 to 4+ and tabulated. As before, the animals were examined daily for the first two weeks after the operation and then weekly thereafter, with tabulation of exercise tolerance, wound healing, skin temperature, and the presence of peripheral pulses as indicated by digital palpation and by Doppler ultrasonography. Limb circumference was carefully tabulated at points 10 cm above and 5 cm below the stifle ("knee"). The animals were serially killed at periods up to 24 months after operation. From selected animals, specimens of skin, muscle, and appropriate blood vessels were taken for pathologic examination. Results Group I. Control Ischemic Limb Preparation In Group I animals, in which a reproducible limb gangrene preparation was attempted, initial attempts demonstrated the remarkable proclivity of the dog to re-establish blood flow to an ischemic area by means of collaterals. However, in the last seven dogs in which complete devascularization was performed, the limbs were cold, tender, and functionless, and the animals never stood or bore weight. Angiography performed on one animal showed a thrombosed femoral artery and no sign of significant collateral ingrowth. All seven animals died or were killed in one to six days because of their clearly terminal state. Specimens of skin and muscle demonstrated early mild to moderate necrosis. § Statham, Hato Rey, Puerto Rico. ' Medrad, Allison Park, Pennsylvania.
245 TECHNIQUE OF FEMORAL AV REVERSAL
A
V
A
V
A
V
4"-
FIG. 2. Staged arteriovenous reversal, the Group III preparation, was accomplished by end-artery-to-side-vein fistula (left) and placement of loose suture around the proximal vein (center) in an initial sitting. A week later, the venous ligature was tightened (right) to complete the procedure.
Group II. Immediate Arteriovenous Reversal Group II animals underwent procedures designed to explore the utility of immediate AVR for limb salvage. These animals consistently developed almost immediate massive edema with average lower leg circumference rising from a control value of 18.67 + 0.5 cm to 28.71 + 1 cm on the third postoperative day (153.7% greater than control), peaking on day 9 at 32.35 + 1.5 cm (172.7% of control). The progression of edema formation with time in both the upper and lower leg is shown in Figure 3. In all cases the animal's limbs were cool and so swollen that usual anatomic land-
LEG EDEMA WITH AV FISTULA
45
30
30
25~2sm
35
20 3
E
0
I-0
.1-4
p'5
30 Control 2
4
6
8
10
12 14
TIME (Days) FIG. 3. Massive unrelenting limb edema followed fistula (Group II) operation.
simple AV
Ann. Surg. * August 1979
JOHANSEN AND BERNSTEIN
246
TABLE 1. Cumulative Data from Group II Dogs, Immediate AVR
Circumferences C/c* Dog No.
Day 0
Day I
Day 3
Day 7
Day 14
II-I
30/18 34/20 31/20 34/20 30/17 28/15 32/20 30/18 34/20 30/17 30/19 32/20
36/24 39/26 38/30 39/26 36/22
38/26 43/28 t 40/28 37/26
40/28 46/30
t
II-2 11-3 11-4 11-5 II-6 11-7 11-8 11-9 11-10 11-ll II-12
46/31 40/30
40/28 t 40/28 t 42/29 40/29
43/32
46/31 42/32 t 48/35
47/36
42/30
46/33
45/32
t 42/31
t
n
12
9
7
6
Mean C Mean c SEM SEM
31.25 18.67
38.89 26.89
40.71 28.71
44.67 31.50
4 44.50 32.35
0.59 0.50
0.69 0.92
0.99 0.96
1.34 1.08
1.38 1.52
t
* C, 10 cm above tibial tubercle; c, 5 cm below tibial tubercle. t Animal found dead, or killed. t Arteriovenous reversals patent at necropsy.
.
; _ ii.
Stand/Weight Bearing (Day) Never 2 days Never 3 days, 2 days, 0 8 days, 0 6 days, 0 0 0
living living
living living
Skin Necrosis
Hemorrhage
+++ +++
++ ++ +++ + ++
0 0 0 ++ 0 0 0 0 ++ +++
++++ ++ + ++ ++ +++ ++++
Time of Death (killing) 8 days 9 days (3 days)t (5 wk) (6 wk)§ 7 days (5 wk) I day: (3 wk)
Iday 3 dayst (5 days)
§ Animal found to have thrombosed AVR, profuse collateral vessel formation on immediate postmortem arteriogram.
marks were effaced, wound healing was poor, and the limbs were minimally functional, even in the longterm survivors. The animals frequently manifested significant subcutaneous hemorrhage and skin necrosis, as noted in Table 1. Doppler ultrasonography failed to reveal a pulse peripheral to the site of anastomosis after the third postoperative day in any animal. The animals generally declined to bear weight on the operated leg, and apparent sepsis appeared to supervene in several cases. Eight of the 12 animals died or were put to death within two weeks. Necropsy showed massive edema and nonviable muscle, and muscle necrosis was demonstrable by microscopy. Four animals survived: edema subsided slightly, but neither limb circumference nor function returned to normal, though these animals bore weight with a limp. Angiography performed on one of these animals showed profuse collateral development and thrombosis of the AV communication (Fig. 4). Of the 12 animals, only 3 had patent AV anastomoses at the time of necropsy.
Group III. Staged Arteriovenous Reversal
F IG. 4. Angiography in a Group II dog. Femoral artery (FA) inDction (A) shows obliteration of main channel of venous tree, but ich collateral formation peripherally (B) with FA reconstitution.
Group III animals underwent procedures designed to explore the use of a staged AVR preparation for limb salvage; formation of an initial arteriovenous fistula (AVF) was followed in 1 week by ligation of the central venous limb of the AVF, thereby creating a "delayed AVR. Limb devascularization was per formed at the first sitting. All 20 animals survived
VOl. 190.9 NO. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
operation and 19 were long-term survivors. One animal was found dead in his cage 1 week after the second operation; he had previously seemed healthy and had walked without difficulty on his operated leg. Necropsy failed to reveal a cause for death. The AV anastomosis was intact and patent, and skin and skeletal muscle seemed viable. Minimal edema was present, with the limb circumference of the operated leg 4% greater than control. Microscopic examination of tissue was not done. All Group III animals stood shortly after AVF formation, but only 6/20 bore weight normally; all manifested evidence for ongoing discomfort in the limb, attempting to avoid manipulation or examination. Wound healing was excellent and occurred per primam. After conversion to AVR, all animals stood within 12 hours and 16/20 bore weight on the reoperated limb within that period: within 1 week all animals walked without obvious limb dysfunction. This general clinical impression of normal function was maintained indefinitely thereafter. All animals manifested mild edema after AVF formation, with initial lower limb circumference of 18.65 ± 0.2 cm rising to 20.05 ± 0.4 on day 3 (107.5% of control), 21.75 ± 0.5 cm at the time of AVR conversion (116.6% of control), and peaking at 21.94 ± 0.4 cm (117.6% of control) at one week after initiation of reversed flow. At six weeks after AVR lower limb circumference had fallen to 20.29 ± 0.9 cm (108.8% of control) (Fig. 5). Doppler ultrasonography documented femoral arterial flow through the venous anastomosis in each of six animals studied at the level of the stifle 3 weeks after
247
FIG. 6. Multiple subcutaneous vascular collaterals are easily visible in a Group III dog several months after AV reversal.
FIG. 5. With staged AV reversal (Group III), leg edema was modest and reversed within several weeks following second stage of
surgery. In two animals an arterial pulse could be palpated manually in a dilated peripheral vein well beyond the stifle. Multiple large vascular collaterals developed subcutaneously (Fig. 6). Four months after surgery three animals were re-examined, and all were found to have a positive Doppler signal in the peripheral limb; one had a palpable pulse 15 cm below the level of AVR. The presence of Doppler signals in operated animals is recorded in Table 2. Angiograms were performed at several times after operation. Examined serially, these demonstrate increasing arterial collateral ingrowth and, in several cases, persistent retrograde venous flow to the level of the ankle (Fig. 7). Graded collateral vessel formation is presented in Table 2. So far as could be determined, 14/19 animals had patent AV communications at 1 month, and 6/7 selected animals demonstrated angiographic patency at ten weeks after operation. No functional difference could be discerned between animals with and without patent AV
operation.
anastomoses.
LEG EDEMA WITH AV REVERSAL
E
32
C.)
I-
31
L.I Control
3 O8
1
I
I
7
14
21
28
-818
-
35
42
TIME (Days)
248
Ann. Surg.
JOHANSEN AND BERNSTEIN TABLE 2. Cumltulaitiv e Datal for Gr-ouip HI Dog.s,
Circumferences C/c*
Stagedl A VR
Doppler Pulses
AVR Patency by Angio.
Dog No.
Day 0
Day 3
Day 7
Day 14
Day 28
Day 42
111-1 111-2 111-3 I11-4 111-5 111-6 111-7 111-8 111-9 111-10 111-11 111-12 111-13 111-14 111-15 111-16 111-17 111-18 111-19 111-20
30/18 34/20 32/20 30/17 28/15 30/19 30/20 29/17 30/20 28/18 30/18 34/20 28/15 30/20 34/20 30/18 32/19 35/21 30/18 34/20
32/20 36/22 33/22 32/20 29/16 31/19 32/22 30/18 31/20 28/19 30/19 35/21
32/22 37/24 34/24 32/21 29/19 30/21 32/23 30/20 31/22 (29/20) 31/22 37/23
30/21
30/21
+
-
+ 0
31/21 35/21 30/18 34/20 35/22 30/20 34/21
33/21 38/25 35/25 32/2 1 29/19 31/22 32/24 30/21 31/23 29/20 31/22 37/22 29/16 31/23 34/22 30/19 34/22 35/24 31/21 35/23
Mean C Mean c
30.90 18.65
32.00 20.05
32.35 21.75
SEM SEM
0.51 0.23
0.54 0.38
n
20
19
C. 10
cm
above stifle,
-
c,
5
cm
32/23 32/21 29/19
3 Wk
32/23 32/20
32/22 29/30 -30/22 35/22
3 1/22 35/23 31/20 34/21
31/21 34/23
31/22 35/24 32.47
30/20
+ +
-
+
-
+
30/16
+
33/22
+ -
33/21
31.29 20.29
0.61 0.50
0.59 0.36
0.58 0.37
0.45 0.90
20
17
12
7
+
-
++ ++
0
+++ + 4++++
+
+
++
+ 0 +
+
++ +++
+ +
+
+ + +
+ +
+ ++ ++ + ++
-+
0 -
+
+
-
0 + +
-++
-
31/20
31.50 21.25
Collaterals (O to ++++)
10 Wk
0 + +
31/20
21.44
4 Wk
+
-
-
below stifle.
16 Wk
-
-
June 1979
Animal found dead in
++++ ++ +++
+
cage: no cause
for death found at
necropsy.
FIG.
Group One
weecs. collateral
period.
Angiography dogs. (b,
(a,
right)
left)
Vol. 190 -No. 2
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
249
FIG. 7 c and d. Multiple films demonstrated persistent flow to level of the ankle.
I FIG. 7 e and f. Midstream aortograms demonstrate, by comparison with the non-
operated left hindlimb, the massive increase in collateral vessels in both arterial and venous phases of the
injections.
Electromagnetic flow determinations before and after the time of AVF formation, before and after AVR conversion, and one week after initiation of AVR in seven animals showed that initial (baseline) femoral artery flow was augmented by AVF formation, as expected. Initial moderate flows with AVR (87.2 ± 24.2 cc/min) rose to flows to 126.7 + 48.3 cc/min
one week later, as demonstrated in Figure 8 and Table 3. Necropsy examinations showed no sign of cardiac chamber or wall hypertrophy; the pertinent vessels showed some evidence for thinning and tortuosity in the artery, while examination of the vein showed thickening of the intima and media with some fibrosis
Ann. Surg. * August 1979
JOHANSEN AND BERNSTEIN
250
FEMORAL ARTERY FLOW WITH AV I2CV=DQA mv nr-c wnopRLI
There has been
no
shortage of innovative attempts
to salvage ischemic extremities in circumstances in
c
which standard revascularization procedures (end-
E
arterectomy, bypass grafting, sympathectomy) have
200 F
failed. Direct muscle revascularization,14 implantation of Ivalon sponge cubes into which the superior epigastric artery was inserted,4 connection of the arterialized in situ saphenous vein into the medullary cavity of the femur,16 and subcutaneous transfer of omental pedicle grafts3 are among the more creative trials undertaken either in experimental animals or in patients.
0
-J
Discussion
100
F
U-
Control
AVF +
AVF 1 wk
AVR
AVR
+ 1 wk
FIG. 8. Flow through femoral artery reaches a peak following AV fistula construction and decreases to contirol levels following proximal venous ligation and conversion of AV fis ,tulatoAVreversal,
That increased blood flow and intense collateral
vessel formation occurs around an arteriovenous communication, either congenital or acquired, has led occasional investigators to explore the use of the AVF for tissue revascularization. Experimental studies in
dogs by Root and Cruz'2 and in turkeys by Matolo et al.11 suggested that an AVF can cause, both by retro-
(Fig. 9a). Serial excrescences in the v ein were felt to represent thrombosed valves (Fig. 9b). No abnormalities were noted upon microscopic exajmination of the skin or muscle. One dog was kept for 24 months a Lfter operation. Clinically the animal did well, without e vidence for disability or exercise intolerance. The arnimal was then anesthetized and underwent angiograph y by techniques described previously. The angiogram (Fig. 10) shows thrombosis of the main AVR channiel but profuse collateral flow through serpiginous paralIlel vessels. The animal was killed and multiple sections of vessels were taken for microscopic examination. Ais before, they demonstrated thrombosis of the valves and arterialization of the veins, with intimal and medial hypertrophy. The AV anastomosis showed an .intimal ingrowth which had rendered it stenotic (2 mm) but not occluded. In summary, heroic denuding of actu,al and potential collateral sources, both ipsilaterally and contralaterally, ultimately led to a canine surgical prepaLration that provided reproducible, irreversible limb ischemia and gangrene in seven animals (Group I). then immediate end-to-end femoral AVR was added tio this preparation (Group II), massive incapacitatirig limb edema resulted, accompanied by incontrove rtible signs of poor tissue perfusion and sepsis. Howe ver, when limb devascularization was accompanied b)y a side-to-side AVF, converted one week later to tru e AVR (Group III), all animals survived the procedure and 19/20 were electively killed up to 24 months lateDr. None demonstrated significant limb edema and s,everal clinical, physiologic, and angiographic meast ires suggested that adequate tissue perfusion was prov rided by AVR.
grade venous flow and by intense arterial pollateralization, perfusion sufficient to nourish an extremity. Pilot clinical studies between 1965 and 1970 by groups in San Francisco and Honolulu implied occasional successes in ameliorating limb ischemia, but these have not been confirmed subsequently. Similar studies with arteriovenous fistulas, without reversal, have also been recently reported from our laboratory.5'6 In these experiments, AV fistula alone offered no protective physiologic benefit against a severe limb ischemia model, in marked contrast to the dramatic benefits to limb perfusion and tissue nutrition which followed the construction of an anastomosis with an AV reversal component. For this reason, and because of the relatively large literature confirming the absence of significant protection from acute ischemia associated with simple AV fistula construction, no "control" group of AV fistula animals was included in the current experimental series. TABLE 3. Electromagnetic Flow Data for Group III Dogs, Staged AVR
Electromagnetic Flow (ml/min)
Dog No.
Control
AVF
III-25 111-26 III-27 III-28 III-29 III-30 III-31 Mean flow SEM
68 52 112 75 98 66 48 74.1 9.5
62 88 162 88 148 90 98 105.1 14.7
AVF + 1 Wk
160 225 420 180 205 165 225.8 43.9
AVR AVR 38 60 180 80 45 120 87.2 24.2
+ I Wk
95 205 80 126.7 48.3
Vol. 190.o NO. 2
FIG. 9a and b. (a) Representative section of vein through which reversed ar-E terial flow has passed 24 ' months in a Group III dog. The intima and media are Tangential section of venous valve in a 24-monthold Group III dog. The valve was markedly shortened and thickened and on gross examination of the vessel surface, the valve was clearly incompetent against reversed flow.
~
REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
251
I-
Flow reversal, perhaps the most radical revascularization concept of all, is also the oldest, predating the beginnings of vascular surgery. The concept was attempted experimentally in 1881, and the first clinical
attempt, by the Spanish surgeon, San Martin y Satrustegui, occurred in 1902.13 Occasional successes engendered enough enthusiasm that widespread clinical trials were carried out prior to 1920. Ultimately,
252
JOHANSEN AND BERNSTEIN
Ann. Surg. * August 1979
FIG. 10. Angiogram of Group III dog 24 months after AVR. A, site of femoral artery injection; B, site of AV anastomosis; C, massive venous collaterals; D, site of ongoing retrograde venous flow; E, new arterial collaterals.
however, the physiologic inconsistency of the theory and its poor results in practice were responsible for discarding the concept. Spurred by the success of new attacks on congenital cardiac defects, Beck2 developed several procedures involving retrograde perfusion of the myocardium via the cardiac veins in patients with coronary artery insufficiency. His coworkers10 attempted to revascularize the cerebral circulation of patients suffering from cerebral palsy, mental retardation, or epilepsy by anastomosing the carotid artery to the jugular vein. At about the same time, Johnston et al.9 reported good to excellent results in each of nine patients with threatened limb gangrene on whom they performed end-to-end femoral triangle AVR. However, in a careful clinical study of such centrally located AVRs. Szilagyi et al. 15 demonstrated rapid stepwise loss of the pressure head due to the succession of venous valves. Alternative bypass and endarterectomy techniques were developed, and vascular surgeons again lost interest in AVR. More recently, Root and Cruz12 demonstrated that tissue perfusion can be supplied by AVR in dogs. Those investigators, as well as Amir-Jahed' and Matolo et al.," further showed that immediate end-to-end AVR is inevitably followed by a massive transudation of fluid and edema formation. Though his attempts were directed toward the amelioration of leg-length dis-
crepancy rather than tissue revascularization, Hiertonn8 demonstrated that formation first of an AVF, followed later by ligation of the central venous limb to yield a true AVR, provided an excellent result, with augmented leg length development and the absence of excessive edema formation. His experiments formed the basis of our two-staged approach. It is extraordinarily difficult to produce limb gangrene in the dog, whose propensity to develop a new and major collateral supply from tiny remote arterial twigs is well recognized. Since the current investigation was designed to ascertain whether arterial flow retrograde in the veins would keep tissues alive, an extreme control preparation was required, i.e., a limb with no other nutritional blood supply that inevitably would undergo ischemic necrosis without a further, successful, therapeutic maneuver. That the current Group I model is a satisfactory "ischemic limb" preparation is supported not only by this study's results, but also by comparison with the essentially identical Group I dogs of Root and Cruz'2 and Group I turkeys of Matolo et al."l The simplest AVR (end-to-end connection offemoral artery and vein) caused severe limb edema and death in two-thirds of the animals. Thrombosis of the AVR was frequently demonstrable, in association with lethal limb gangrene. The staged AVR preparation, in which an initial side-to-side arteriovenous fistula was con-
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REVASCULARIZATION OF ISCHEMIC CANINE HINDLIMB
verted to AVR by ligation of the central venous limb, was very acceptable. Limb edema was not a prominent feature, and other clinical and quantitative criteria suggested that these devascularized limbs now had an adequate blood supply. A number of "physiologic fallacies" have been presented as evidence against the usefulness of AVR in limb revascularization: 1) The flow must traverse competent venous valves. However, in situ saphenous vein femoralpopliteal grafts conduct similarly reversed flow following valve destruction. 2) Centripetal venous tributaries might shunt blood to the superficial venous system and decompress the inflow arterial pressure head, to the extent that little or no perfusion of the distal microcirculation would occur. However, the success of the Group III preparation speaks against this concern. Further, ligation of perforating veins connecting the deep and superficial venous systems could block such shunting, if necessary. 3) Can arterial blood presented retrograde to the terminal circulation carry out normal cellular nutrition and clearance of metabolites? Microvascular work by Zweifach17 using vital dyes suggests that exchange of small molecules can occur with such reverse perfusion, and Heimbecker et al.7 demonstrated oxygen uptake across a retroperfused capillary bed. 4) If the venous tree is used as inflow, what will serve as the venous outflow? In our preparation, the superficial venous tree is used as an inflow route. It is likely that new deep venous collaterals rapidly form and/or enlarge, as demonstrated by the Group III animals with ongoing arterial inflow (Fig. 8) in the absence of excessive edema formation (Fig. 5).
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in the management of severe peripheral ischemia. The current study suggests that the excessive edema formation that occurs with immediate end-to-end AVR can be avoided by forming an initial end-artery-to-sidevein AVF, with later ligation of the central venous limb to cause AVR. Nineteen of 20 dogs enjoyed longterm survival with such a preparation. Several theoretical fallacies exist, asserting that AVR cannot perform retrograde perfusion of the terminal circulation. These issues can be only partially answered from the published reports and are under active investigation in our laboratory. References 1. Amir-Jahed, A. K.: Revascularization of Lower Extremities by Reversal of Blood Flow with and without Lumbar Sympathectomy: An Experimental Study. Surgery, 59:243, 1966. 2. Beck, C. S.: Surgical Operations for Coronary Artery Disease. In Encyclopedia of Thoracic Surgery, Vol. II. Berlin, Springer-Verlag, 1959, p. 779. 3. Casten, D. F. and Alday, E. S.: Omental Transfer for Revascularization of the Extremities. Surg. Gynecol. Obstet., 126:301, 1971. 4. Friedman, E. W., Lambert, P. B. and Frank, H. A.: Vascular Connections Established by Arteries Implanted into the Lower Extremity with Plastic Sponge as an Intermediary. Surgery, 60:386, 1966. 5. Gausewitz, S., Gerard, D. F., Dilley, R. B. and Bernstein, E. F.: Arteriovenous Anastomosis (AVA) and Arteriovenous Fistula (AVF) in Revascularizing the Ischemic Canine Hindlimb. Surg. Forum, 29:211, 1978. 6. Gerard, D. F., Dilley, R. B. and Bernstein, E. F.: The Acute Physiologic Effects of an Arteriovenous Anastomosis in the Devascularized Canine Hindlimb. Surg. Forum, 28:206, 1977. 7. Heimbecker, P., Vivien, T. and Blalock, A.: Experimental Reversal of Capillary Flow. Circulation 4:116, 1951. 8. Hiertonn, T.: Arteriovenous Fistula for Discrepancy in Length of Lower Extremities. Acta Orthop. Scand., 31:25, 1961. 9. Johnston, C. G., Jordan, P. and Cloud, T.: Arteriovenous Anastomosis in Traumatic Vascular Lesions. Ann. J. Surg.,
80:809, 1950. 10. McKhann, C. F., Belknap, W. D. and Beck, C. S.: Cervical Arteriovenous Anastomosis in Treatment of Mental Retardation, Convulsive Disorders, and Cerebral Spasticity.
Ann. Surg., 132:162, 1950.
The current experimental thus has provided 1) a reproducible canine model for limb ischemia, 2) proof of unacceptably massive edema formation with immediate end-to-end AVR, and 3) evidence that conversion of an initial AVF into an AVR in a limb previously made irreversibly ischemic appears to salvage the limb without excessive edema formation. The concept of staged venous flow reversal therefore appears worthy of further investigation as an approach to the severely ischemic extremity. Summary Reversal of the circulation arises phoenix-like from the ashes of authoritative assertions of its inutility
11. Matolo, N. M., Cohen, S. W. and Wolfman, E. F.: Use of an Arteriovenous Fistula for Treatment of Severely Ischemic Extremity: Experimental Evaluation. Ann. Surg., 184:622,
1976. 12. Root, H. D. and Cruz, A. B., Jr.: Effects of an Arteriovenous Fistula on the Devascularized Limb. JAMA, 191:109, 1965. 13. San Martin y Satrustegui, A.: Chirurgie de l'appareil Circulatoire: l'anastomose Arterio-veineuse. Sem. Med., p. 395, 1902. 14. Shionoya, S., Ban, I. and Nakata, Y.: Skeletal Muscle Revascularization by Vascular Implantation. J. Cardiovasc. Surg., 14:208, 1973. 15. Szilagyi, D., Jay, G. D. and Munnell, E. D.: Femoral Arteriovenous Anastomosis in the Treatment of Occlusive Arterial Disease. Arch. Surg., 63:435, 1951. 16. Vetto, R. M. and Belzer, F. O.: Use of an Arterio-bone Fistula in Advanced Ischemia. Surg. Forum, 16:131, 1965. 17. Zweifach, B. W.: The Structural Basis of Permeability and Other Functions of Blood Capillaries. Cold Spring Harbor Symposia on Quantitative Biology, 18:216, 1940.
