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The fate of the donor artery in extraanatomic revascularization
The fate of the donor artery in extraanatomic revascularization Amdrico Dinis da Gama, M D , Lisbon, Portugal Favorable long-term results have been reported after femorofemoral bypass in the treatment ofiliofemoral occlusive disease. Functional alterations in the donor artery, occurring after the implantation of the graft, have been considered as having an arresting effect on the progress of the occlusive disease, which explains the favorable long-term results. However, until now, the intrinsic mechanism of this phenomenon has remained unexplained. Little attention has been devoted to the evaluation of the natural history of the donor artery. To achieve this purpose, 18 patients previously operated on for femorofemoral bypass, with a normal patent graft, were submitted to angiographic evaluation, from 8 to 57 months after the operation (mean 22 months). The angiograms were compared with the preoperative films to assess the progress of the occlusive disease in the donor artery. A slight but significant dilatation of the proximal donor arterial segment was doctunented in every case, affecting the external iliac and common femoral arteries. The pathogenesis of this phenomenon is discussed. It may be related to decreased peripheral resistance and increased blood flow occurring in the donor arterial segment, reported after the implantation of the shunt. This dilatation of the donor artery may have a compensatory effect for local atherosderotic stenosis, thereby explaining the favorably long duration of the femorofemoral bypasses, which has been emphasized since the early days of extraanatomic revascularization. A similar phenomenon may occur in the vessels of the upper extremity, after axillofemoral revascularization. (J VASC SURG 1988;8:106-11.)
Extraanatomic bypass grafts have a definite place in the armamentarium of the vascular surgeon in the management of some forms of aortoiliac diseases. Despite extensive experience for more than two decades of utilization, several controversial points remain, concerning their hemodynamic implications and the durability of their clinical results. 1-s It has been postulated that success of the revascularization becomes almost completely dependent on the integrity and fimctional capacity of the donor artery. 68 Since the early days of extraanatomic bypasses, Vetto, 9 the pioneer of the femorofemoral shunt, stated that " . . . the hemodynamic changes produced by the operation may have an arresting effect upon the progress of arterial occlusion" (page 164). Several years later, Ehrenfeld et al. I° described the hemodynamics of the femorofemoral shunt in a canine model. These authors could demonstrate increased blood flow in the proximal donor arterial segment, after a crossover femorofemoral bypass, without deFrom the SantaMaria Hospital and Universityof LisbonMedical School. Reprint requests: Amdrico Dinis da Gama, MD, Praqa Nuno Rodrigues dos Santos, 13-10° E, 1600, Lisboa, Portugal. 106
creased flow to the distal vessels on the donor side. Over the years, these documented hemodynamic factors have been used to explain the favorable longterm clinical results of the femorofemoral shunt, thereby confirming Vetto's initial prediction, n,~2 However, it has been difficult for us to understand the mechanism by which the functional alterations may alter the progress of the lesions in the donor artery. A lack of information concerning the natural history of the donor artery led us to proceed with the study of its long-term behavior. To achieve this purpose we have evaluated, with angiography, a series of patients subjected to femorofemoral bypass and followed up for the past five years. MATERIAL AND METHODS The series is composed of 18 patients, 17 men and one woman, having an average age of 56 years (range 35 to 77 years) who were operated on during the period March 1980 to March 1985o Fifteen patients (83%) were operated on for intermittent clandication and the remaining three (17%) had rest pain, trophic necrotic changes, or both. The evaluation of each patient included history and physical examination, blood and urinalysis, cardiac consulta-
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization
107
Table I. Preoperative and postoperative diameters of the donor artery Donor artery External iliac
Commonfemoral
Patient
Preop
Postop
Difference
Preop
Postop
Difference
1 2 3 4 5 6 7 8
4.9 8.2 7.0 6.0 6.5 6.1 5.9 7.2
9.7 9.8 7.8 8.2 6.9 6.6 7.1 7.8
+4.8 +1.6 +0.8 +2.2 +0.4 +0.5 +1.2 +0.6 +2.0 +1.2 +1.0 +0.8 +0.7 +1.6 +1.5 +0.6 +1.3 +1.1
5.1 7.4 6.8 6.8 5.9 5.8 6.3 7.0 7.8 8.5 5.9 6.7 7.1 6.5 6.3 7.0 5.8 6.4
7.3 9.0 7.8 8.2 6.5 6.9 7.4 8.4 9.5
+2.2 +1.6 +1.0 +1.4 +0.6 +1.1 +1.1 +1.4 +1.7 +1.2 +1.2 +1.1 +1.2 +1.0 +1.3 +1.5 +1.1 +0.8
9
7.7
9.7
10 11 12 13 14 15 16 17 18
8.8 6.8 7.3 6.4 6.9 7.2 7.3 6.5 5.8
10.0 7.8 8.1 7.1 8.5 8.7 7.9 7.8 6.9
9.7 7.1 7.8 8.3 7.5 7.6 8.5 6.9 7.2
NOTE: Data expressed as diameter in millimeters.
tion and noninvasive laboratory studies, followed up by translumbar aortography. Coronary artery disease (50%), chronic Obstructive pulmonary disease (22%), arterial hypertension (33%), diabetes mellitus (22%), and cerebrovascular insufficiency (11%) were found to bc the most common associated diseases. All the patients smoked cigarettcs. The angiographic diagnosis of unilatcral athcrosclerofic iliofemoral occlusive disease was made in every case. Associated fcmoropopliteal occlusion was found in seven (39%) of the recipient limbs and in three (17%) of the donor limbs. Clinical indications for the cxtraanatomic procedure were high surgical risks in 10 patients, obesity in two, and in the remaining six patients the operation was indicated as prophylaxis of male sexual dysfunction, often reported as a consequence of conventional retroperitoneal aortoiliac surgery. Seventeen patients had general anesthetic; in one patient local anesthesia was used because of severe respiratory insufficiency. Fourteen patients received an 8 mm Dacron tube graft and autologous saphcnous vein was used in four patients. All the patients in this series having a normal patent graft were subjected to postoperative angiography, from 8 to 57 months after the operation (mean 22 months). No selective criteria were used for the angiography, other than the consent of the patient to proceed with the examination: The artc-
riograms were done exactly in the same fashion as before the operation. After light general sedation with 2 nag of intramuscular diazcpam and with the patients under local anesthesia (30 ml of 2% lidocaine (xylocaine)), translumbar aortography was performed with a 50 ml injection of sodium-meglumine iothalamate solution (25 ml/sec). Sequential exposures were taken at the abdomen, thighs, and legs. The purpose of the study was the evaluation of the donor artery behavior to assess the progress of the local atherosclerotic occlusive disease. The diameters of the external iliac and common femoral arteries of the donor side (considered the donor artery) were carefully measured in the preoperative film of each patient and compared with the control angiogram at the same level of each vessel. The head of the femur and the length of the fifth lumbar vertebra were also measured and compared with the control angiograms to confirm the identical conditions in which each examination was made. Classical statistical analysis was used and the resuits were expressed as mean + standard deviation. The mean preoperative diameter was compared with the mean postoperative diameter of the donor artery. The results were also evaluated according to the nature and size of the graft, as well as to the length of the revascuiarization. Paired t test was used to determine the significance of the different groups, p < 0.05 being considered statistically significant.
loumal of VASCULAR SURGERY
108 d a G a m a
Fig. 1. Proximal dilatation of the donor artery, 17 months after crossover femorofemoral bypass graft.
Table II. Highly significant increase in diameter of the donor artery Preop Postop (ram) (ram) External lilac Common femoral
6.8 ± 0.9 6.6 ± 0.8
8.1 ± 1.1 7.9 ± 0.9
NOTE: p < 0.001.
Table IV. N o n s i g n i f i c a n t alteration according to the m e a n d u r a t i o n o f the revascularization follow.up
External iliac C o m m o n femoral
>22 mo
<22 mo
1.5 + 1.3 1.3 _+ 0.4
1.1 _+ 0.4 1.2 ± 0.2
NOTE: p > 0.2.
Table III. N o n s i g n i f i c a n t alteration, according to thc nature and size of the graft Donor artery
Autologous vein ~ (ram)
Synthetic graft~, (ram)
External iliac C o m m o n femoral
1.1 + 0.8 1.3 ± 0.2
1.4 ± 1.1 1.2 -+ 0.4
NOTE: p > 0.5. ~Diameter of 4 to 5 ram. 1-Diameter o f 8 ram.
RESULTS Early surgical results were considered most satisfactory; there were no operative deaths and no postoperative complications have occurred. Hemodynamic studies showed remarkable improvement of pedal systolic indexes. They increased from 0.49 + 0.06 to 0.91 -+ 0.05 on the recipient limb with a patent superficial femoral artery and from 0.29 -+ 0.1 to 0.55 -+ 0.09 with that artery occluded. The 5-year cum~ative patency rate was 89.5%.
The results of the evaluation of the donor artery were found almost constant in every patient. Instead of a decrease, as might be expected by the nature of the disease, an increase in the diameter of the donor arterial segment was generally found (Table I; Figs. 1, 2, and 3). This increase in diameter ranged from 6.8 __- 0.9 mm to 8.1 -+ 1.1 mm of the original diameter of the external iliac artery and from 6.6 __+ 0.8 mm to 7.9 + 0.9 mm for the common femoral artery (Table II). An assessment of the con'anon iliac artery diameter was also made. Although a discrete increase in size was noted, this was neither constant nor significant enough to warrant consideration. In addition, no significant correlation could be established with the nature and size of the graft or the length of the revascularization (Tables III and IV). However, bccause the series was so small, no significant conclusions can be drawn. A stenotic lesion in the common iliac artery was found in only one patient 28 months after surgery (Fig. 4). This was a 48-year-old diabctic man, who was hypertensive and a heavy, smoker; however,
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization 109
Fig. 2. Proximal dilatation of the donor artery, 57 months after crossover femorof~moral bypass graft.
Fig. 3. Proximal dilatation of the donor artery, 34 months after crossover femorofemoral saphenous vein bypass graft.
there was a slight increase in the diameters of the external iliac and common femoral arteries. Two nonsignificant stenoses were found in the recipient artery anastomosis; however, none required surgical treatment. DISCUSSION Atherosclerosis is a diffuse and progressive disease. Surgery temporarily modifies th e natural history of atherosclerotic diseases; many late surgical failures
may be explained by the deteriorating nature of its course, affecting either the proximal, 'the distal arterial bed, or the operated vessel. 1a-15 Concerning the fcmorofemoral bypass, several authors 9-12have admitted that the hemodynamic conditions created by the operation could have an arresting effect on the progress of the disease in the arterial donor segment, but there has been a lack of evidence to support its mechanism. In the present study, an unquestionable dilatation of the proximal
Journal of VASCULAR SURGERY
110 da Galicia
Fig. 4. Significant stenosis of the common iliac donor artery, 28 months after crossover femorofemoral bypass graft.
donor artery occurred after the operation and has never been reported. This phenomenon should be regarded as quite similar to that one already described as a consequence of arteriovenous fistulas 16 and reported initially by Holman 17 and Leriche. I8 Decreased peripheral resistance in the proximal arterial bed to the fistula is considered the main factor involved in the genesis of its dilatation. ~9a~ The increased blood flow, which is recognized as the physiologic response to the diminished peripheral resistance, may cause a compromise of the arterial wall structure. 22 The intrinsic strength and structural integrity of the arterial wall may be affected; thus the artery becomes dilated, and true aneurysms have already been reported, in some longstanding acquired arteriovenous fistulas. 2a'24 In the femorofemoral shtmt, the decreased peripheral resistance comes from the perfusion of an extraarterial bed by the donor artery, which is the recipient arterial bed. Increased blood flow results in this segment, as already shown by Ehrenfeld et al. m in their animal experiments. This increased blood flow results in a slight dilatation of the donor artery. Several authors have emphasized the unexpected good long-term results of the clinical use of femorofemoral bypasses. According to Plecha and Plecha, 2s who reported their 10-year experience in 113 patients, they found only one patient in whom there was any significant progression of the occlusive disease in the donor iliac artery. Some functional alterations occurring as a consequence of the physiologic
response to the shunt have been mentioned to explain the favorable long-term results of this procedure. However, in the present study, we demonstrated the occurrence of a structural alteration, the dilatation of the proximal donor artery, which should also be interpreted as a part o f the physiologic response of the arterial system to the femorofemoral bypass. A major and beneficial effect of this phenomenon arises from the fact that the dilatation of the donor artery may compensate for atherosclerotic stenosis in this vessel, thereby contributing to the preservation of the patency of the donor artery as well as the permeability of the graft. The favorable outcome of the extraanatomic bypasses may thus be explained by structural changes of the donor artery rather than by functional alterations, as expressed by others. We anticipate that a similar phenomenon may occur in the subclavian-axillary artery, related to the axillofemoral bypass, which is more difficlt to document as a consequence of the natural limitations of angiography in this area. REFERENCES 1. Brief DK, Alpert J, Parsonnct V. Crossover femoro-femoral grafts. Compromise or preference: a reappraisal. Arch Surg 1972;105:889-95. 2. Donaldson MC, Louras IC, Bucknam CA. Axillofemoral bypass: a tool with a limited role. J VAsc SURG 1986;3:75763. 3. Kalman PG, Hosang M, Cina C, et al. Current indications for axillounifemoral and axillobifemorai bypass grafts. I VAsc SURG 1987;5:828-32.
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization 111
4. Kalman PG, Hosang M, Johnston KW, et al. The current role for femorofemoral bypass. J VAsc SURG 1987;6:71-6. 5. Lamerton A, Nicolaides AN, Kenyon JR, et al. Selection for long term results of femorofemoral bypass. In: Greenhalgh R, ed. Extra-anatomic and secondary arterial reconstruction. London: Pitman, 1982. 6. BriefDK, Brener BJ, Alpert J, et al. Crossover femoro-femoral grafts followed up five years or more. Arch Snrg 1975; 110:1294-9. 7. Dick LS, BriefDK, Alpert J, et al. A 12-year experience with femorofemoral crossover grafts. Arch Surg 1980; 115:135965. 8. Parsonnet V, Alpert J, Brief DK. Femorofemoral and axillofemoral grafts--compromise or preference. Surgery 1970; 67:26-39. 9. Vetto RM. The fEmorofemoral shunt--an appraisal. Am J Surg 1966;112:162-5. 10. Ehrenfeld WK, Harris JD, Wylie EJ. Vascular "steal" phenomenon. An experimental study. Am J Surg 1968;116: 192-7, 11. Shin CS, Chandry AG. The hemodynamics of extra-anatomic bypass grafts. Surg Gynec01 Obstet 1979;148:567-75. 12. Sumner DS, Strandness DE Jr. The hemodynamics of the femorofemoral shunt. Surg Gynecol Obstet 1972;134:62936. 13. Haimovid H. Patterns of arteriosclerotic lesions of the lower extremity. Arch Surg 1967;95:918-33. 14. Malone JM, Moore WS, Goldstone J. The natural history of bilateral aortofemoral bypass grafts for ischemia of the lower extremities. Arch Surg 1975;110:1300-6. 15. Warren R, Gomez RL, Marston JP, et al. Femoropopliteal
16.
17. 18. 19.
20.
21.
22. 23.
24.
25.
arteriosclerosis obliterans--arteriographic patterns and rates of progression. Surgery 1964;55:135-49. Lindenauer SM, Thompson NW, Kraft RO, et al. Late complications of traumatic arteriovenous.fistulas. Surg Gynecol Obstet 1969;129:525-34. Holman E. The anatomic and physiologic effects of an arteriovenous fistula. Surgery 1940;8:362-9. Leriche R. An&rysmes art&ielles et fismles art6rio-veineuses. Paris: Masson et Cie, 1949. Ingebrigsten R, Johansen K, Muller O, et al. Blood pressure of the proximal artery in experimental artcriovenous fistulas of long standing. Acta Chit Scand 1960;253 (suppl): 134-42. Sako Y, Varco RL. Arteriovenons fistula: results of management of congenital and acquired forms, blood flow measurements and observations on proximal arterial degcneration. Surgery 1970;67:40-53. Schenk WG Jr, Martin JW, Leslie MB, et al. The regional hemodynamics of chronic expcrimental arteriovenous fistulas. Surg Gynecol Obstet 1960;110:44-53. Stehbens WE. Blood vessels changes in chronic experimental arteriovenous fistulas. Surg Gynecol Obstct 1968;127:32733. Kieser TM, Walley VM, McPhail NV. Abdominal aortic ectasia resulting from peripheral traumatic artcriovenous fismlization. J Vase SURG 1987;5:882-6. Shumacker HB Jr. Aneurysm development and degenerative changes in dilated artery proximal to arteriovenous fistula. Surg Gynecol Obstet 1970;130:636-43. Plecha FR, Plecha FM. Femorofemoral bypass grafts: tenyear experience. J VAsc SURG 1984;1:555-61.
Extraanatomic bypass grafts have a definite place in the armamentarium of the vascular surgeon in the management of some forms of aortoiliac diseases. Despite extensive experience for more than two decades of utilization, several controversial points remain, concerning their hemodynamic implications and the durability of their clinical results. 1-s It has been postulated that success of the revascularization becomes almost completely dependent on the integrity and fimctional capacity of the donor artery. 68 Since the early days of extraanatomic bypasses, Vetto, 9 the pioneer of the femorofemoral shunt, stated that " . . . the hemodynamic changes produced by the operation may have an arresting effect upon the progress of arterial occlusion" (page 164). Several years later, Ehrenfeld et al. I° described the hemodynamics of the femorofemoral shunt in a canine model. These authors could demonstrate increased blood flow in the proximal donor arterial segment, after a crossover femorofemoral bypass, without deFrom the SantaMaria Hospital and Universityof LisbonMedical School. Reprint requests: Amdrico Dinis da Gama, MD, Praqa Nuno Rodrigues dos Santos, 13-10° E, 1600, Lisboa, Portugal. 106
creased flow to the distal vessels on the donor side. Over the years, these documented hemodynamic factors have been used to explain the favorable longterm clinical results of the femorofemoral shunt, thereby confirming Vetto's initial prediction, n,~2 However, it has been difficult for us to understand the mechanism by which the functional alterations may alter the progress of the lesions in the donor artery. A lack of information concerning the natural history of the donor artery led us to proceed with the study of its long-term behavior. To achieve this purpose we have evaluated, with angiography, a series of patients subjected to femorofemoral bypass and followed up for the past five years. MATERIAL AND METHODS The series is composed of 18 patients, 17 men and one woman, having an average age of 56 years (range 35 to 77 years) who were operated on during the period March 1980 to March 1985o Fifteen patients (83%) were operated on for intermittent clandication and the remaining three (17%) had rest pain, trophic necrotic changes, or both. The evaluation of each patient included history and physical examination, blood and urinalysis, cardiac consulta-
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization
107
Table I. Preoperative and postoperative diameters of the donor artery Donor artery External iliac
Commonfemoral
Patient
Preop
Postop
Difference
Preop
Postop
Difference
1 2 3 4 5 6 7 8
4.9 8.2 7.0 6.0 6.5 6.1 5.9 7.2
9.7 9.8 7.8 8.2 6.9 6.6 7.1 7.8
+4.8 +1.6 +0.8 +2.2 +0.4 +0.5 +1.2 +0.6 +2.0 +1.2 +1.0 +0.8 +0.7 +1.6 +1.5 +0.6 +1.3 +1.1
5.1 7.4 6.8 6.8 5.9 5.8 6.3 7.0 7.8 8.5 5.9 6.7 7.1 6.5 6.3 7.0 5.8 6.4
7.3 9.0 7.8 8.2 6.5 6.9 7.4 8.4 9.5
+2.2 +1.6 +1.0 +1.4 +0.6 +1.1 +1.1 +1.4 +1.7 +1.2 +1.2 +1.1 +1.2 +1.0 +1.3 +1.5 +1.1 +0.8
9
7.7
9.7
10 11 12 13 14 15 16 17 18
8.8 6.8 7.3 6.4 6.9 7.2 7.3 6.5 5.8
10.0 7.8 8.1 7.1 8.5 8.7 7.9 7.8 6.9
9.7 7.1 7.8 8.3 7.5 7.6 8.5 6.9 7.2
NOTE: Data expressed as diameter in millimeters.
tion and noninvasive laboratory studies, followed up by translumbar aortography. Coronary artery disease (50%), chronic Obstructive pulmonary disease (22%), arterial hypertension (33%), diabetes mellitus (22%), and cerebrovascular insufficiency (11%) were found to bc the most common associated diseases. All the patients smoked cigarettcs. The angiographic diagnosis of unilatcral athcrosclerofic iliofemoral occlusive disease was made in every case. Associated fcmoropopliteal occlusion was found in seven (39%) of the recipient limbs and in three (17%) of the donor limbs. Clinical indications for the cxtraanatomic procedure were high surgical risks in 10 patients, obesity in two, and in the remaining six patients the operation was indicated as prophylaxis of male sexual dysfunction, often reported as a consequence of conventional retroperitoneal aortoiliac surgery. Seventeen patients had general anesthetic; in one patient local anesthesia was used because of severe respiratory insufficiency. Fourteen patients received an 8 mm Dacron tube graft and autologous saphcnous vein was used in four patients. All the patients in this series having a normal patent graft were subjected to postoperative angiography, from 8 to 57 months after the operation (mean 22 months). No selective criteria were used for the angiography, other than the consent of the patient to proceed with the examination: The artc-
riograms were done exactly in the same fashion as before the operation. After light general sedation with 2 nag of intramuscular diazcpam and with the patients under local anesthesia (30 ml of 2% lidocaine (xylocaine)), translumbar aortography was performed with a 50 ml injection of sodium-meglumine iothalamate solution (25 ml/sec). Sequential exposures were taken at the abdomen, thighs, and legs. The purpose of the study was the evaluation of the donor artery behavior to assess the progress of the local atherosclerotic occlusive disease. The diameters of the external iliac and common femoral arteries of the donor side (considered the donor artery) were carefully measured in the preoperative film of each patient and compared with the control angiogram at the same level of each vessel. The head of the femur and the length of the fifth lumbar vertebra were also measured and compared with the control angiograms to confirm the identical conditions in which each examination was made. Classical statistical analysis was used and the resuits were expressed as mean + standard deviation. The mean preoperative diameter was compared with the mean postoperative diameter of the donor artery. The results were also evaluated according to the nature and size of the graft, as well as to the length of the revascuiarization. Paired t test was used to determine the significance of the different groups, p < 0.05 being considered statistically significant.
loumal of VASCULAR SURGERY
108 d a G a m a
Fig. 1. Proximal dilatation of the donor artery, 17 months after crossover femorofemoral bypass graft.
Table II. Highly significant increase in diameter of the donor artery Preop Postop (ram) (ram) External lilac Common femoral
6.8 ± 0.9 6.6 ± 0.8
8.1 ± 1.1 7.9 ± 0.9
NOTE: p < 0.001.
Table IV. N o n s i g n i f i c a n t alteration according to the m e a n d u r a t i o n o f the revascularization follow.up
External iliac C o m m o n femoral
>22 mo
<22 mo
1.5 + 1.3 1.3 _+ 0.4
1.1 _+ 0.4 1.2 ± 0.2
NOTE: p > 0.2.
Table III. N o n s i g n i f i c a n t alteration, according to thc nature and size of the graft Donor artery
Autologous vein ~ (ram)
Synthetic graft~, (ram)
External iliac C o m m o n femoral
1.1 + 0.8 1.3 ± 0.2
1.4 ± 1.1 1.2 -+ 0.4
NOTE: p > 0.5. ~Diameter of 4 to 5 ram. 1-Diameter o f 8 ram.
RESULTS Early surgical results were considered most satisfactory; there were no operative deaths and no postoperative complications have occurred. Hemodynamic studies showed remarkable improvement of pedal systolic indexes. They increased from 0.49 + 0.06 to 0.91 -+ 0.05 on the recipient limb with a patent superficial femoral artery and from 0.29 -+ 0.1 to 0.55 -+ 0.09 with that artery occluded. The 5-year cum~ative patency rate was 89.5%.
The results of the evaluation of the donor artery were found almost constant in every patient. Instead of a decrease, as might be expected by the nature of the disease, an increase in the diameter of the donor arterial segment was generally found (Table I; Figs. 1, 2, and 3). This increase in diameter ranged from 6.8 __- 0.9 mm to 8.1 -+ 1.1 mm of the original diameter of the external iliac artery and from 6.6 __+ 0.8 mm to 7.9 + 0.9 mm for the common femoral artery (Table II). An assessment of the con'anon iliac artery diameter was also made. Although a discrete increase in size was noted, this was neither constant nor significant enough to warrant consideration. In addition, no significant correlation could be established with the nature and size of the graft or the length of the revascularization (Tables III and IV). However, bccause the series was so small, no significant conclusions can be drawn. A stenotic lesion in the common iliac artery was found in only one patient 28 months after surgery (Fig. 4). This was a 48-year-old diabctic man, who was hypertensive and a heavy, smoker; however,
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization 109
Fig. 2. Proximal dilatation of the donor artery, 57 months after crossover femorof~moral bypass graft.
Fig. 3. Proximal dilatation of the donor artery, 34 months after crossover femorofemoral saphenous vein bypass graft.
there was a slight increase in the diameters of the external iliac and common femoral arteries. Two nonsignificant stenoses were found in the recipient artery anastomosis; however, none required surgical treatment. DISCUSSION Atherosclerosis is a diffuse and progressive disease. Surgery temporarily modifies th e natural history of atherosclerotic diseases; many late surgical failures
may be explained by the deteriorating nature of its course, affecting either the proximal, 'the distal arterial bed, or the operated vessel. 1a-15 Concerning the fcmorofemoral bypass, several authors 9-12have admitted that the hemodynamic conditions created by the operation could have an arresting effect on the progress of the disease in the arterial donor segment, but there has been a lack of evidence to support its mechanism. In the present study, an unquestionable dilatation of the proximal
Journal of VASCULAR SURGERY
110 da Galicia
Fig. 4. Significant stenosis of the common iliac donor artery, 28 months after crossover femorofemoral bypass graft.
donor artery occurred after the operation and has never been reported. This phenomenon should be regarded as quite similar to that one already described as a consequence of arteriovenous fistulas 16 and reported initially by Holman 17 and Leriche. I8 Decreased peripheral resistance in the proximal arterial bed to the fistula is considered the main factor involved in the genesis of its dilatation. ~9a~ The increased blood flow, which is recognized as the physiologic response to the diminished peripheral resistance, may cause a compromise of the arterial wall structure. 22 The intrinsic strength and structural integrity of the arterial wall may be affected; thus the artery becomes dilated, and true aneurysms have already been reported, in some longstanding acquired arteriovenous fistulas. 2a'24 In the femorofemoral shtmt, the decreased peripheral resistance comes from the perfusion of an extraarterial bed by the donor artery, which is the recipient arterial bed. Increased blood flow results in this segment, as already shown by Ehrenfeld et al. m in their animal experiments. This increased blood flow results in a slight dilatation of the donor artery. Several authors have emphasized the unexpected good long-term results of the clinical use of femorofemoral bypasses. According to Plecha and Plecha, 2s who reported their 10-year experience in 113 patients, they found only one patient in whom there was any significant progression of the occlusive disease in the donor iliac artery. Some functional alterations occurring as a consequence of the physiologic
response to the shunt have been mentioned to explain the favorable long-term results of this procedure. However, in the present study, we demonstrated the occurrence of a structural alteration, the dilatation of the proximal donor artery, which should also be interpreted as a part o f the physiologic response of the arterial system to the femorofemoral bypass. A major and beneficial effect of this phenomenon arises from the fact that the dilatation of the donor artery may compensate for atherosclerotic stenosis in this vessel, thereby contributing to the preservation of the patency of the donor artery as well as the permeability of the graft. The favorable outcome of the extraanatomic bypasses may thus be explained by structural changes of the donor artery rather than by functional alterations, as expressed by others. We anticipate that a similar phenomenon may occur in the subclavian-axillary artery, related to the axillofemoral bypass, which is more difficlt to document as a consequence of the natural limitations of angiography in this area. REFERENCES 1. Brief DK, Alpert J, Parsonnct V. Crossover femoro-femoral grafts. Compromise or preference: a reappraisal. Arch Surg 1972;105:889-95. 2. Donaldson MC, Louras IC, Bucknam CA. Axillofemoral bypass: a tool with a limited role. J VAsc SURG 1986;3:75763. 3. Kalman PG, Hosang M, Cina C, et al. Current indications for axillounifemoral and axillobifemorai bypass grafts. I VAsc SURG 1987;5:828-32.
Volume 8 Number 2 August 1988
Fate of the donor artery in extraanatomic revascularization 111
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