Infrapopliteal bypasses to severely calcified, unclampable outflow arteries: Two-year results

Infrapopliteal bypasses to severely calcified, unclampablc outflow arteries: Two-year results Bruce D. Misare, M D , F r a n k B. Pomposelli, Jr., M D , Gary W. G i b b o n s , M D , D a v i d R. Campbell, M D , D o r o t h y V. Freeman, M D , and F r a n k W. L o G e r f o , M D ,

Boston, Mass. Purpose:Although severe, circumferential calcification of distal outflow vessels is frequently encountered, its effect on bypass graft patency rates has not been well established. Methods: Using a computerized vascular registry database, we conducted a retrospective review of 1957 bypass grafts with distal anastomoses to infrapopliteal vessels performed at a single institution between 1990 and 1995. Of these cases, 101 procedures involved outflow arteries classified by the operating surgeon as severely calcified and unclampable (requiring intraluminal occluders for vascular control), whereas in 105 cases the outflow arteries had no calcification present at the distal anastomotic site. The remaining cases had varying intermediate degrees of calcification and were not analyzed. Indication for bypass procedure was limb-threatening ischemia in 90% of severe calcification cases and in 84% of cases without calcification. Atherosclerotic risk factors were similar except for the presence of diabetes (92% vs 74%, p < 0.001), creatinine level > 2.0 m g / d l (21% vs 8%, p < 0.01), and dialysis dependency (17% vs 3%, p < 0.001), all of which were more prevalent in the severe calcification group. Infrapopliteal distal anastomotic location and type of conduit (>90% autogenous vein) were comparable between groups. Results: Primary patency, secondary patency, and foot salvage rates at 24 months were 60%, 65%, and 77% for the severe calcification group and 74%, 82%, and 93% for the no calcification group, respectively. With secondary procedures comprising 26% of cases in each group, data from the 150 primary procedures were reanalyzed separately. In this primary procedure group, 24-month primary patency, secondary patency, and foot salvage rates were 66%, 69%, and 77% for the severe calcification group and 84%, 90%, and 96% for the no calcification group, respectively. Although patency and salvage rates were consistently lower for the severe calcification group in all analyses, these differences did not achieve significance by log-rank life-table analysis at 2-year follow-up. Perioperative 30-day mortality (0.99% severe calcification vs 0.95% no calcification) and 24-month survival rates (84% severe calcification vs 83% no calcification) were also similar between groups. Conclusion: These data suggest that effective techniques exist to perform infrapopliteal bypasses to severely calcified, unclampable outflow arteries with results comparable with those obtained with clampable, tmcalcified vessels. The finding of severe, circumferential calcification of outflow target arteries should not dissuade vascular surgeons from distal bypass for limb salvage indications. (J Vase Surg 1996;24:6-16.

From the Division of Vascular Surgery, Deaconess Hospital, Harvard Medical School, Boston. Presented at the Twenty-second Annual Meeting of the New England Society for Vascular Surgery, Montreal, Quebec, Canada, Sept. 28-29, 1995. Reprint requests: Frank B. Pomposelli, Jr., MD, Division of VascularSurgery,DeaconessHospital, Suite 5B, 110 FrancisSt., Boston, MA 02215. Copyright © 1996 by The Society for Vascular Surgery and International Societyfor CardiovascularSurgery, North American Chapter. 0741-5214/96/$5.00 + 0 24/6/71879

Severe, circumferential calcification o f outflow target arteries remains a challenge to vascular surgeons who perform distal infrapopliteal reconstructions. Bypass procedures to such vessels are technically demanding with regard to dissection, vascular control, creation of arteriotomy, and anastomotic technique. Thus initial poor results led to the labeling of such calcification as a poor prognostic factor for both graft patency and limb salvage and the labeling of

JOURNAL OF VASCULAR SURGERY Volume 24, Number 1

many of these paticnts as "unreconstructablc. ''I In 1986 Ascer and colleagues2 described the technical feasibility of infrapopliteal bypasses to such heavily calcified rocklike arteries by fracturing the calcified vessel before anastomosis. In their series of 36 patients, the 3-year graft patency rate was reported as 47%, which was not statistically different from the patency rate for anastomoses to less-calcified arteries. Rubin et al.3 reported a series of 38 patients who underwent femorotibial bypass for calcific arterial disease in 1989. Although the severity of outflow vascular calcification in this study was defined primarily by radiologic criteria, the 3-year primary graft patency rate in this study was 80%, again not statistically different from bypasses to less-calcified vessels. Subsequent publications by other groups have mainly focused on describing the technical aspects of dealing with such severely calcified arteries and have not reported the resultant bypass graft patcncy rates. 4-7 Patients with severe peripheral arterial calcification often have diabetes mellitus with some component of renal insufficiency. Previous reports by our group and others have documented the durability of infrapopliteal and inframalleolar level bypasses in primarily diabetic populations, with 2-year primary graft patency rates ranging from 72% to 85% when autogenous vein was used. 8-~ Bypass results in patients with end-stage renal disease are also documented and carry similar short-term patency rates, although overall limb salvage and patient survival rates remain disappointingly p o o r . 16-19 However, no modern report that used current vascular surgical techniques and reported standards suggested by the Society for Vascular Surgery (SVS) and the International Society for Cardiovascular Surgery (ISCVS) 2° has defined vascular bypass results stratified by the severity of peripheral arterial calcification. Accordingly, this retrospective study was undcrtaken to assess the effects of circumferential crural and pedal arterial calcification on distal bypass graft patency and limb salvage rates. PATIENTS A N D M E T H O D S

Using a computerized vascular registry, a retrospective review of all bypass operations performed to outflow vessels below the popliteal artery at Deaconess Hospital by five surgeons (F.B.P., G.W.G., D.R.C., D.V.F., and F.W.L.) from January 1990 to January 1995 was conducted. During these 1957 bypass grafts, the attending operating surgeon classificd the outflow vessel by degree of calcification. Calcificalion was considered at the final site of distal anastomosis after further proximal or distal dissection

Misare et al.

7

as necessary to isolate the optimal anastomotic site on the outflow artery. No patient in this series was refused a bypass solely on the basis of severity of vascular calcification. O f these 1957 cases, 101 procedures involved vessels that were classified as having severe circumferential calcification. Criteria for this category included the inability to obtain control of arterial flow with standard vessel loops or atraumatic vascular clamps, which necessitated the use ofintraluminal vessel occluders. 21,22 None of these cases were performed with tourniquet technique. In 105 cases the attending surgeon listed no calcification as being present at the distal anastomotic site. Thus 206 of 1957 cases, or a total of 10.5% of all bypasses performed, fit into these two extreme categories of vascular calcification. The remaining 90% of infrapopliteal bypasses had varying intermediate degrees of calcification present that could not be objectively quantitated between surgeons; therefore, they were not included in this subgroup analysis. Preoperative patient demographic characteristics and atherosclerotic risk factors are summarized in Table I. Groups were similar with regard to sex and age. Atherosclerotic vascular risk factors were notable for the higher incidence of diabetes mellitus, renal failure (defined as a serum creatininc level >2.0 m g / d l ) , dependency on either hemodialysis or peritoneal dialysis, and the presence of a functioning renal allograft, all of which were more prevalent in the group with severe distal arterial calcification. Indications for surgery are summarized in Table II. More than 90% of patients underwent a bypass procedure for limb-threatening ischemia with either ischcmic rest pain, nonhealing ischemic ulceration, or extremity gangrene/cellulitis being present. O f note, severe tissue gangrene was present more often in patients with severely calcified arteries. Only one patient in each group underwent a concurrent inflow procedure along with the distal bypass. Twenty-six percent of cases performed in both groups were secondary procedures for failed or failing bypass grafts. These secondary procedures consisted of either completely new bypass grafts or revision jump grafts from a failing graft to a new distal anastomotic location. Thrombectomies or simple patch angioplasties were excluded from patient analysis in this study. 2°'23Angioscopic evaluation of conduit was used equally between groups and was used in all cases where an in situ technique, arm vein, or composite conduit was required. Table III summarizes each patient subgroup by inflow artery, outflow artery, and bypass conduit used. There was no difference in the level of infrapopliteal

8

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Misare et aL

T a b l e I. Demographics o f patient population u n d e r g o i n g inffapopliteal bypass grafts Severe calcification

No. of patients No. of procedures Age (yr) Mean Range Sex Male Female Risk factors Prior vascular surgery Diabetes Diet controlled Oral agent Insulin-dependent Tobacco Coronary artery disease Prior coronary bypass Stroke Hypertension Creatinine >2.0 mg/dl Dialysis Hemodialysis Peritoneal Kidney transplant

No calcification

93 101

p

99 105

67 29-90

68 37-91

0.259

74 (73%) 27 (27%)

67 (64%)

0.177

38 (36%)

0.177

74 93 9 24 68

69 78 9 30 66 87 89 26 16 65 8 3 3 0 0

0.290 0.001" 0.950 0.527 0.663 0.482 0.845 0.408 0.464 0.670 0.009* 0.001" 0.078 0.003* 0.001"

79

87 20 20 59 21 17 9 8 9

(73%) (92%) (9%) (24%) (67%) (78%) (86%) (20%) (20%) (58%) (21%) (17%) (9%) (8%) (9%)

(66%) (74%) (9%) (29%) (63%) (83%) (85%) (25%) (15%) (62%) (8%) (3%) (3%) (0%) (0%)

*Statistically significant.

T a b l e I I . Indications for bypass and associated procedures p e r f o r m e d in 206 patients with severely calcified or uncalcified distal outflow arteries Severe calcification

Indications Limb-threateningischemia Ulcer Rest pain Gangrene Cellulitis Popliteal aneurysm Disabling claudication Concurrent inflow procedure Redo/revision Angioscopy

91 75 24 45 44 2 8 1 26 54

(90%) (74%) (24%) (45%) (44%) (2%) (8%) (1%) (26%) (54%)

No calcification

88 69 30 30 32 4 13 1 27 54

(84%) (66%) (29%) (29%) (30%) (4%) (12%) (1%) (26%) (51%)

p

0.218 0.224 0.527 0.021" 0.06I 0.683 0.360 0.950 0.950 0.782

*Statistically significant.

outflow site, with 50% o f the severe calcification g r o u p and 38% o f the no calcification g r o u p having bypasses to the inframalleolar level. Popliteal inflow was used m o r e c o m m o n l y for grafts to severely calcified outflow vessels, in contrast to femoral level inflow being used m o s t often for grafts to uncalcified vessels. Finally, the type o f c o n d u i t used was similar in b o t h calcification groups. A u t o g e n o u s vein was harvested whenever possible and was used in 90% o f the 206 total cases. Choice o f in situ, reverse, or nonreverse vein technique was based on individual patient characteristics and surgical preference. Twenty-seven percent o f cases in each g r o u p were p e r f o r m e d with

either arm vein or composite vein because o f prior harvesting or inadequacy o f the greater saphenous vein. Surgical technique for m a n a g e m e n t o f the outflow arteries was similar for all five participating surgeons. After exposing the potential outflow artery, careful proximal and distal dissection was p e r f o r m e d as necessary to locate the least diseased p o r t i o n o f artery for anastomosis. I f n o calcification was present, proximal and distal control was obtained with vessel loops. W h e n severe circumferential calcification was encountered and control with multiple, serially placed vessel loops or atraumatic clamps was n o t possible,

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Misare et al.

9

Table III. Inflow artery, outflow artery, and conduit used in infrapopliteal bypasses to 101 severely calcified and 105 uncalcified outflow arteries Severe calcification

Inflow Iliac/common femoral Distal SFA/AK popliteal BK popliteal Tibial Previous bypassgraft Total Outflow Tibial-peronealtrunk Peroneal Tibial (anterior/posterior) Pedal Tarsal/plantar Total Conduit In-situ saphermusvein Non-reverse saphenous vein Peverse saphenous vein Arm vein Composite vein PTFE/vein patch Total

No calcification

32 23 30 3 13 101

(32%) (23%) (30%) (2%) (13%) (100%)

55 26 13 1 10 105

(52%) (25%)

4 25 32 27 13 101

(4%) (25%) (31%) (27%) (13%) (100%)

1 19 45 33 7 105

1%) 18%) 43%) 31%) 7%)

14 32 20 15 12 8 101

(14%) (31%) (20%) (15%) (12%) (8%) (100%)

25 26 12 14 15 13 105

24%) 25%) 12%) 13%) 14%) 12%) 100%)

(12%) (1%)

(10%)

p

0.002* 0.747 0.003*

0.362 o.511

(100%) 0.205 0.308 0.114 0.540 0.161

100%)

0.077 0.282 0.124 0.842 0.682 0.360

SFA, Superficialfemoralartery; AK, above knee; BK, below knee; PTFE, polytetrafluoroethylene.

*Statisticallysignificant. arterial backflow was controlled with intraluminal vascular occluders (Bio-Vascular, Inc.; St. Paul), as illustrated in Fig. 1.21,22 If adequate outflow vascular control still was not obtained, inflow occlusion at the site o f the proximal anastomosis was used. No cases were performed with tourniquet technique. An arteriotomy was made by scoring the arterywith a No. 15 blade or a Beaver Micro-sharp blade (BectonDickenson, Franklin Lakes, N.J.) until the lumen was encountered, then extended with fine Potts scissors. Routine vascular anastomoses werc then executed under loupe magnification with running simple sutures o f 6-0 or 7-0 Prolene (Ethicon, Inc.; Somerville, N.J.) on cardiovascular cutting needles. Extreme care was taken to have small, closely spaced bites o f both arterial and vein walls. No special techniques such as arterial crushing, 2 plaque fracturing, 6 or localized endarterectomy a were used to prepare the calcified artery for anastomosis. Patient follow-up examinations for assessment o f patency and foot salvage occurred at 2 weeks, then every 3 m o n t h s for the first year, and at 6-month intervals thereafter. Graft patency was determined by the presence o f a palpable graft pulse or by the foot/brachial pressure index. Foot salvage was defined as retention o f the affected limb without need for amputation above the metatarsal level. Primary patency, secondary patency, foot salvage, and patient survival rates were analyzed by the life-table method,

compared by the log-rank test, and listed as mean + SEM, in accordance with criteria established by the Joint Council of the ISCVS and the SVS. 2° Patient characteristics, graft characteristics, and complication rates were compared between groups by ~2 analysis. RESULTS A total of 101 bypasses were performed in 93 patients in the severe calcification group; 99 patients underwent 10 5 bypasses in the no calcification group. Follow-up ranged from 1 to 36 months, with a mean of 12.7 months. The 30-day graft patency rate was 99% for severely calcified arteries, with one early failure. For uncalcified vessels, two early graft failures occurred with a 98% 30-day primary patency rate. Twenty-four-month bypass graft patency and foot salvage rates were compared by severity o f distal arterial calcification. Given the large number o f secondary procedures included in the initial analysis (26%), further subgroup analysis also was performed including only those graft procedures performed as a primary procedure. Primary patency results are reported in life-table form in Table IV and summarized graphically in Fig. 2. For all procedures, the primary patency rates for the severely calcified and uncalcified artery groups were 60.2% _+ 10.5% and 73.9% + 10.0%, respectively (p = 0.395). With only primary procedures considered, the primary patency

10

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Misare et al.

Fig. 1. Insertion of intraluminal vascular occludcr through arteriotomy provides hemostasis and retraction of arterial wall during construction of anastomosis. Occluder then may be removed immediately before completing anastomosis to allow backflushing of vessel. (Photo used with permission of Bio-Vascular, Inc.)

T a b l e I V . Life-table analysis o f p r i m a r y p a t e n c y for all cases by severity o f calcification Interval (months)

Severe calcification 0-1 i-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-24 No calcification 0-1 1-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-24

Cumulative patency (%)

Grafts at risk

Failed grafts

Withdrawn

Interval patency

98 97 87 71 56 37 30 25 19 14 14

1 2 5 6 4 3 1 1 1 0 1

0 8 11 9 15 4 4 5 4 0 7

0.990 0.978 0.939 0.910 0.918 0.914 0.964 0.956 0.941 1.000 0.905

100.0 99.0 96.8

103 101 85 67 48 36 31 25 19 17 14

2 2 4 4 4 0 0 1 0 0 0

0 14 14 15 8 5 6 5 2 3 7

0.981 0.979 0.949 0.933

100.0 98.1 96.0 91.1 85.0

rates were 66.0%_+ 10.3% a n d 8 3 . 7 % _ 10.2% for severe a n d n o calcification g r o u p s , respectively ( p = 0.202). N e i t h e r c o m p a r i s o n r e a c h e d statistical significance at 2 years. S e c o n d a r y p a t e n c y was successfully r e s t o r e d in e i g h t grafts in t h e severe calcification g r o u p a n d in six grafts in t h e n o calcification g r o u p , w i t h resultant rates s u m m a r i z e d in Fig. 3. F o r the severely calcified arteries, the s e c o n d a r y p a t e n c y rate was 65.0% _+ 10.3%, whereas the rate was 81.6% +_ 8.6% for uncalcified arteries ( p = 0.523). F o r the p r i m a r y p r o c e d u r e s u b g r o u p analysis, t h e s e c o n d a r y p a t e n c y rates were 68.8%-+ 9.9% for calcified vessels a n d

0.909

1.000 1.000 0.956 1.000 1.000 1.000

90.9

82.7 75.9 69.4 66.9 64.0 60.2 60.2

77.3 77.3 77.3

73.9 73.9 73.9

SE (%)

0.00 1.01 1.86 3.25 4.60 6.13 7.01 7.70

8.81 10.15 10.15 0.00 1.35 2.08 3.32 4.75 6.14 6.61 7.37

8.66 9.16 10.09

89.9% 4- 8.3% for uncalcified vessels ( p = 0.118). Again, these results were n o t statistically significant by l o g - r a n k life-table analysis at 2 years. Eleven b e l o w - l m e e a m p u t a t i o n s a n d o n e aboveknee a m p u t a t i o n were p e r f o r m e d in patients w i t h severely calcified arteries. F o r patients w i t h n o o u t flow-vessel calcification, six b e l o w - k n e e a n d one a b o v e - k n e e a m p u t a t i o n s were required. Resultant f o o t salvage rates arc listed by life-table analysis in Table V a n d are s u m m a r i z e d graphically in Fig. 4. N o statistical difference was n o t e d in c o m p a r i s o n w h e n b o t h p r i m a r y a n d s e c o n d a r y p r o c e d u r e s were included. W i t h s e c o n d a r y p r o c e d u r e s excluded, h o w -

J O U R N A L OF VASCULAR SURGERY Volume 24, Number 1

Misare et al.

10o

100

,73.9% c

= 0.523

0

e-

p = 0.395

60

_; ,0

60

65.0%

•- - o - Severe Calcification - - ~ - - No Calcification

O. 4)

- . c . - Severe C a l c l f l c x t l o n No C a l c i f i c a t i o n

o

_>

(.1

ra

160.2%

a.

=

81.6%

80

8o

E

11

.>

40

E o

20

I I

I

I

I

12

4

6

8

I

I

I

I

20

[

10 12 14 16 18

24

I

I

I

4

6

8 10 12 14 16 18

I

I

i

I

I 24

Duration of Follow-up (months)

Duration of Follow-up (months) Severe 98 97 87 71 56 37 30 25 19 15 No Ca1103101 85 67 48 36 31 25 19 17 Patients Remaining at Interval

i l 12

Severe98 97 87 74 62 40 33 28 23 17 No Ca] 103101 86 68 49 38 33 27 22 20 Patients Remaining at Interval

14 14

15 16

100 100

°•"

83.7%

8O

p = 0.202

e-

366.0%

e0

Severe Calcification No Calcfficatlon

n

o

=

80

p = 0.118

¢J 68.8%

60

Severe Calcification - - ~ - - No Calcification

O.

o

.>

_; ,0 E

,.,,,.

e=

.>

0

89.9%

A

E .m

20

(J !1 12

4

I

I

6

8

1

I

I

I

I

10 12 14 16 18

24

Duration of Follow-up (months) Severe 75 74 68 56 45 31 26 22 18 15 NoCal 75 75 63 49 36 27 23 18 17 15 Patients Remaining at interval

14 11

40

20

II

i

I

12

4

8 10 12 14 16 18

I

i

I

[

i 24

Duration of Follow-up (months) Severe 7574 68 57 48 33 28 24 21 17 NoCal 7575 64 50 37 29 25 20 19 17 Patients Remaining at Interval

15 12

Fig. 2. Twenty-four-month primary graft patency rate for infrapopliteal bypasses by log-rank life-table analysis. Top graph summarizes data for all cases. Bottom graph includes data from bypasses performed as the primary procedure only.

Fig. 3. Twenty-four-month secondary graft patency rate for infrapopliteal bypasses by log-rank life-table analysis. Top graph demonstrates patency ratc for all cases. Bottom graph summarizes results excluding secondary procedures.

ever, foot salvage tended to be worse in patients with severe vascular calcification (76.5% + 10.3% calcified vs 95.5% :k 6.8% uncalcified, p = 0.06). Table VI lists systemic and local complications encountered in this series. All patients who underwent peripheral bypass received invasive cardiac monitoring (pulmonary arterial and arterial catheters) and were followed in a monitored step-down unit until stable at preoperative weight. Each patient group had one perioperative death, each as a conse-

quence o f myocardial infarction. The resultant 30-day operative mortality rate was 1%. The 24-month patient survival rate was 84% in the severe calcification group and 83% in the no calcification group, which was not statistically different. DISCUSSION With the growing acceptance o f the feasibility o f very distal bypass to tibial and inframalleolar vessels, more vascular surgeons are encountering patients

12

JOURNALOF VASCULARSURGERY July 1996

Misare et al.

Table V. Life-table analysis of foot salvage for all cases by severity of calcification Interval (months)

Severe calcification 0-1 1-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-24 No calcification 0-1 1-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-24

Limbs at r i s k

Amputations

Withdrawn

Interval salvage

Cumulative salvage (%)

SE (%)

98 98 88 75 64 40 34 29 23 18 14

0 2 2 1 4 1 1 0 0 1 0

0 8 11 10 20 5 4 6 5 3 9

1.000 0.979 0.976 0.986 0.926 0.973 0.969 1.000 1.000 0.939 1.000

100.0 100.0 97.9 95.6 94.3 87.3 84.9 82.3 82.3 82.3 77.3

0.00 0.00 1.51 2.32 2.81 4.92 5.66 6.43 7.22 8.16 9.84

103 101 87 70 52 41 36 27 22 20 15

2 0 0 2 1 0 0 0 0 0 0

0 14 17 16 10 5 9 5 2 5 8

0.981 1.000 1.000 0.968 0.979 1.000 1.000 1.000 1.000 1.000 1.000

100.0 98.1 98.1 98.1 95.0 93.0 93.0 93.0 93.0 93.0 93.0

0.00 1.35 1.45 1.62 2.95 3.84 4.10 4.74 5.25 5.50 6.35

Table VI. Morbidity and mortality rates for bypasses to calcified (n = 101) or uncalcified (n = 105) distal outflow arteries Severe calcification

Systemic complications Hemorrhage Myocardial infarction Heart failure Pneumonia Pulmonary embolus Arrhythmia Renal failure Clostridiai diarrhea Urinary tract infection Local complications Wound infection Hematoma Wound dehiscence Lymphocele 30-day mortality rate

No calcification

1 2 1 0 0 1 1 2 5

(1%) (2%) (1%) (0%) (0%) (1%) (1%) (2%) (5%)

3 3 1 2

0 (0%)

1.000

2 0 3 5

(2%) (0%) (3%) (5%)

0.950 0.490 0.950 0.950

3 3 0 0 1

(3%) (3%) (0%) (0%) (1%)

3 4 0 1 1

(3%) (4%) (0%) (1%) (1%)

0.950 0.950 1.000 0.950 0.950

with severe circumferential calcification o f otherwise p a t e n t outflow vessels w h e n a t t e m p t i n g distal anastomoses. A l t h o u g h patchy calcification is c o m m o n in almost all patients with atherosclerotic peripheral occlusive disease, generalized vascular calcification is m o r e p r o m i n e n t in the diabetic p o p u l a t i o n . Patients with end-stage renal disease o n dialysis also are p r o n e to severe vascular calcification, leading to the description " a z o t e m i c arteriopathy. ''24 I n accordance with this finding, o u r study f o u n d that patients with severe peripheral vascular calcification had higher incidences

(3%) (3%) (1%) (2%)

p

0.622 0.950 0.950 0.498

o f diabetes, elevated creatinine levels, a n d the n e e d for dialysis or renal transplantation. Ascer et al.2 f o u n d similar results in 77% o f patients with severely calcified, rocldike arteries w h o had diabetes. Despite extensive calcification, quite c o m m o n l y a small area o f relative sparing can be f o u n d in otherwise p a t e n t distal vessels. O u t f l o w vessels in our series only m e t criteria for severe calcification if n o such area c o u l d be located in the area chosen for distal anastomosis. T h u s only i 0 1 o f 1957 infrapopliteal bypass procedures, or 5% o f total cases, required the m e t h o d s described to deal

JOURNAL 0,1~VASCULAR SURGERY Volume 24, Number 1

with the calcified outflow vessel. Again, this finding correlates with Ascer's finding that the fracture technique was required to deal with dense calcification in 10% of all total bypasses to infrapopliteal vessels performed at their institution) Diabetic patients tend to have calcific arterial occlusive ,disease, which is often limited to the crural arteries. <~° Results from this study showed that in patients with severe distal arterial calcification, 92% of whom had diabetes mellitus, the inflow vessel was most commonly the popliteal artery. In contrast, in patients with no calcification, 74% of whom had diabetes, the predominant inflow source was more proximal in the femoral artery. Quinones-Baldrich et al.9 had similar findings in their series of very distal bypasses in which 80% of patients had diabetes, and inflow was obtained from the poplitcal artery in 54% of cases. 'Thus shorter popliteal-tibial or poplitealpedal bypass procedures are often possible in patients with severe vascular calcification. Previous studies have documented no difference in patency rate between bypasses with femoral or popliteal inflow sites. 2s Adequate preoperative assessment of both inflow and inframalleolar-level outflow arteries with digital subtraction angiography is thus critical in identiffing patients with reconstructible occlusive disease, regardless of the presence of severe calcification. Autogenous vein is believed to be critical to the success of infrapopliteal bypasses and was used in more than 90% of procedures in this series. Although there are isolated reports of improved results with techniques such as a Taylor vein patch on distal tibial polytetrafl[uoroethylene anastomoses, 26'27 prosthetic material remains a suboptimal conduit for crural or pedal arteries. Arm vein, although inferior to saphenous vein, remains a viable alternative to prosthetic graft material and was used in 14% of cases in our report. 26 Our experience has shown that angioscopy can be beneficial in identifying defects in autogenous conduit, ,especially in cases in which arm vein or composite', vein with venovenostomies are used. 2s'29 When available, saphcnous vein may be used in either in situ, reverse, or nonrcvcrse technique, depending on length and vessel size considerations. In previous studies of distal bypass procedures in diabetic patients, no difference in saphenous vein graft patency rate has been documented between bypasses using any of these techniques. 2s Many different methods have been described to deal with severe circumferential calcification present at sites of proposed distal anastomosis. 2-8 Our current technique involves adequate careful dissection to expose the: target artery, taking care not to fracture the

Misare et al.

13

10o 93.0% p = 0.174

g.

77.3%

J

Severe Calciflcatlom No Calcification

r~ 0

0

I I 12

f I 4 6

Duration

I [ I I I [ 8 10 12 14 16 18 of Follow-up

(months)

Severe 98 98 88 75 64 40 34 29 23 18 No Ca1103101 87 70 52 41 36 27 22 20 Patients Remaining at Interval

24 1"4 15

10o ~95.5% p = 0.061 ~)

176.5% ~

60

Severe Calcification No Calcmcatlon

¢n 0

_> ; 40 am=

==

E

"~ 0

20

0

I f I 12 4

I 6

Duration

Severe 7575 No Cal 75 75

I f I I I I 8 10 12 14 16 18 of Follow-up

(months)

69 57 48 31 27 23 19 15 64 51 36 27 23 17 16 14 Patients Remaining at Interval

24 13 9

Fig. 4. Twenty-four-month foot salvage rates by log-rank life-table analysis. Top graph shows results for all cases included in the study. Bottom graph illustrates data for primary bypass procedures only. calcified plaque present. An arteriotomy then is made by scoring the artery with a No. 15 blade until blood return is encountered. The arteriotomy is then extended as necessary with tibial Ports scissors. No fracturing of the calcified wall, as described by Ascer et al.,e is performed, and all possible attempts are made to maintain integrity of the intimal surface. Endarterectomy of the outflow vessel is never used. Vascular control, when not possible with vessel loops, is obtained with silicone bulb-tipped intraluminal vessel

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occluders placed proximally and distally in the artery. 21'22 Sizing of the luminal diameter is determined with a small metal coronary dilator. Experience has demonstrated that a bulb-tipped vessel occluder that is 0.25 mm larger than the measured vessel lumen usually provides effective hcmostasis and does not traumatize the intima or disrupt plaque. In addition, inflow occlusion at the site of proximal anastomosis usually improves hemostasis. Tourniquet technique has not been used, although it has been proved effective in other series, s'7 The anastomosis is then created end-to-side with a running 6-0 or 7-0 Prolene suture on a cardiovascular cutting needle. Using this size of cutting needle, we have found it unnecessary to use other tools, such as Keith needles or dental drills, to penetrate the calcified vessel wall. 3'6 Loupe magnification and fine instruments are routinely used for all distal anastomoses. Suture-hole bleeding on the calcified artery, if encountered, is easily controlled with Surgicel (Johnson & Johnson, Arlington, Tex.). Using the above techniques, this study demonstrates no statistically different short-term primary or secondary patency rates when infrapopliteal bypass procedures are performed to either severely calcified or uncalcified outflow arteries. Intermediate degrees of calcification between these two extremes, which account for more than 90% of patients who undergo peripheral bypass, would thus be expected to have similar acceptable patency rates. Our 69% primary patency rate for primary bypasses to severely calcified, unclampable crural and pedal arteries concurs well with other patient series that showed 3-year primary patency rates of 47% to 80%.2,3,9 These results also remain comparable with the 70% to 90% infrapopliteal bypass graft primary patency results reported in recent series of arterial reconstructions in patients with diabetes. 8-t~ Although not achieving statistical significance, foot salvage rates at 2 years tended to be lower in patients with severe vascular calcification, especially when secondary procedures were excluded. This result may be in part explained by the greater percentage of patients with severe calcification in whom gangrene was the indication for revascularization. It may also be related to the greater number of patients with end-stage renal disease in the severe calcification group. Numerous studies have documented a higher tissue loss and amputation rate in vascular patients with renal failure, often in the setting of successful, patent bypass grafts. 16-19 Potential limitations of this study include the relatively small number of patients in each group and the limited 2-year follow-up period. Compared with

previous similar reports in the literature that contained 362 and 383 patients, this study represents the largest series to date that stratified patients by degree of arterial calcification. Further patient accrual and follow-up will be required to see whether the trend to lower patency and limb salvage rates exhibited by this study will become statistically significant beyond 24 months. CONCLUSION This series supports the findings of previous smaller reports that demonstrated that circumferentiall3) calcified infrapopliteal outflow arteries are not a major obstacle to successful lower extremity arterial reconstruction. The presence of vascular calcification on preoperative radiologic studies should not preclude attempts at arterial reconstruction. Furthermore, the use of intraluminal vessel occluders for hemostatic control in such vessels appears to be an effective alternative to tourniquet occlusion. All vascular surgeons should have a technique in their armamentarium for dealing with these challenging distal vessels to maximize the chance for ischemic limb salvage. REFERENCES 1. Dardik H, Ibrahim IM, Dardik II. The role of the peroneal artery for limb salvage. Ann Surg 1979;189:189-98. 2. Ascer E, Veith FJ, White-Flores SA. Infrapopliteal bypasses to heavily calcified rock-like arteries: management and results. Am J Surg 1986;152:220-3. 3. Rubin JR, Persky J, Lukens MC, Plecha EJ, Graham LM. Femoral-tibial bypass for calcific arterial disease. Am J Surg 1989;158:146-50. 4. Wagner WH, Treiman RL, Cossman DV, et al. Tourniquet occlusion technique for tibial artery reconstruction. J Vase Surg 1993;18:637-47. 5. Semel L, Schu W, Aust JC, Bredenberg CE. Atraumatic control in calcified arteries. Ann Vase Surg 1988;2:73-4. 6. White JV, Gass J. Preparation of the calcified tibial artery for bypass grafting. Surg Gynecol Obstet 1990;171:165-6. 7. Shindo S, Tada Y, Sato O, et al. Esmarch's bandage technique in distal bypass surgery. J Cardiovasc Surg 1992;33:609-12. 8. Pomposelli FB Jr, Marcaccio EJ, Gibbons GW, et al. Dorsalis pedis arterial bypass: durable limb salvage for foot ischemia in patients with diabetes mellitus. J Vase Surg 1995 ;21:375-84. 9. Quinones-Baldrich WJ, Colburn MD, Ahn SS, Gelabert HA, Moore WS. Very distal bypass for salvage of the severely ischemic extremity. Am J Surg 1993;166:117-23. 10. Pomposelli FB Jr, Jepsen SJ, Gibbons GW, et al. Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations. J Vase Surg 1990;11:745-52. 11. Kwolek CJ, Pomposelli FB, Tannenbaum GA, et al. Peripheral vascular bypass in juvenile-onset diabetes mellitus: are aggressive revascularization attempts justified? J Vase Surg 1992;15: 394-401. 12. Gibbons GW, Burgess AM, Guadagnoli E, et al. Return to weli-being and function after infralnguinal revascularization. J Vase Surg 1995;21:35-45.

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13. Shah DM, Chang BB, Fitzgerald K/Vl,Kaufman IL, Leather RP. Durability of the tibial artery bypass in diabetic patients. Am J Surg 1988;156:133-5. i4. Ascer E, Veith FJ, Gupta SK. Bypasses to plantar arteries and other tibial branches: an extended approach to limb salvage. J Vase Surg 1988;8:434-41. 15. Rosenblatt MS, Quist WC, SidawyAN,PaniszynCC, LoGerfo FW. Results of vein graft reconstruction of the lower extremity in diabetic and nondiabetic patients. Surg Gynecol Obstet 1990;17I:331-5. 16. Whittemore AD, Donaldson MC, Mannick JA. Infrainguinal reconstruction for patients with chronic renal insufficiency. J Vase Surg 1993;I7:32-41. 17. Harrington EB, Harrington ME, Schanzer H, Haimov M. End-stage renal disease--is infrainguinal limb revascnlarization justified? [1Vase Surg 1990;12:689-94. i8. Chang BB, Paty PSI(, Shah DM, Kaufman JL, Leather RP. Results ofinfrainguinal bypassfor limb salvagein patients with end-stage renal disease. Surgery 1990;108:742-7. 19. Edwards JM, Taylor LM Jr, Porter JM. Limb salvage in end-stage renal disease (ESRD): Comparison of modern results in patients with and without ESRD. Arch Surg 1988; 123:1164-8. 20. Ruthertbrd RB, Flanigan DP, Gupta SK, et al. Suggested standards for reports dealing with lower extremity ischemia. J Vase Surg 1986;4:80-94. 21. Edwards WH, Mulherin JL. An internal vessel occluder for distal limb bypass.Ann Thorac Surg 1979;27:472-3.

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22. Griffin JB, Meng RL. Internal vessel occlusion: an improved technique for small vessel anastomosis. J Vase Surg 1986;4: 616-8. 23. De Frang RD, Edwards JM, Moneta GL, Yeager RA, Taylor LM Jr, Porter JM. Repeat leg bypassafter multiple prior bypass failures. J Vase Surg 1994;19:268-77. 24. Conn J, Krumlovksy FA, DelGreco F, Simon NM. Calciphylaxis: etiology of progressive vascular calcification and gangrene?Ann Surg 1973;177:207-10. 25. Pomposelli FB Jr, Jepsen SJ, Gibbons GW, et al. A flexible approach to infrapoplitealvein grafts in patients with diabetes mellitus. Arch Surg I991;126:724-9. 26. Taylor RS, McFarland RJ, Cox M, Chester JF. Improved technique for polytetraflnoroethylene bypass grafting: longterm results using anastomotic vein patches. Br J Surg 1992; 79:348-54. 27. Loh A, Chester IF, TaylorRS. PTFE bypassgrafting to isolated popliteal segments in critical limb ischaemia. Eur J Vase Surg 1993;7:26-30. 28. Marcaccio EJ, Miller A, Tannenbaum GA, et al. Angioscopically directed interventions improve arm vein bypass grafts. J Vase Surg I993;17:994-1004. 29. Holzenbein TJ, Miller A, Tannenbaum GA, et al. Role of angioscopyin reoperation for the tailing or failedinfrainguinal vein bypass graft. Ann Vase Surg 1994;8:74-91.

Submitted Oct. 4, 1995; accepted Jan. 12, 1996.

DISCUSSION Dr. David C. Brewster (Boston, Mass.). I congratulate the Deaconess group on another important and clinically relevant study on a topic related to infrainguinalreconstruction. Your results are really remarkable, in terms of both patency rates and your perioperative mortality rate for what is recognized to be often a clinically high-risk category of patients. Obviously calcification presents technical challenges related both to the control of vessels and to the actual construction of the anastomosis. I would agree with you that the "flow arrester" intraluminal device may be useful, but my perspective has come to favor tourniquet control, which you briefly mentioned. I find this method of more utility and believe that it is actually a safer method than the introduction of intraluminal devices that may themselves produce technical problems. I would be interested in your comments on why the technique with a tourniquet and exsanguination with an Esmarch bandage was not used in any of your patients. Second, I think it would be helpful to expand just a bit about constructing the anastomosis. You mentioned special needles, and I think these are important, but surely even with cutting-tip needles some vessels may be so densely calcified that they cannot be penetrated, so is there ever a role for crushing of calcified vessel walls or local endarterectomy to construct the anastomosis? Dr. Bruce D. Misare. We agree with Dr. Brewster that

the tourniquet technique is an effective alternative to intraluminal occluders in controlling heavily calcified vessels. We have not adopted it because intraluminal occlusion has proved satisfactory in cases in our experience. Either method appears to be sufficient. We believe that vascular surgeons should use the method with which they feel most comfortable. With regard to anastomotic technique, in most cases the cardiovascular cutting needles will penetrate even heavily calcified arterial walls. We have found that the portion of the arterial wall directly adjacent to the arteriotomy is usually softened during cutting with Potts scissors. Placing very small suture bites in this area usually allows penetration. We never crush the wall and rarely remove any calcium from the artery, taldng care to preserve intimal integrity. Dr. J o n a t h a n Woodson (Boston, Mass.). Dr. Misare, could you please clarify something for me? It appeared as you constructed your life-table analysis that very few patients were available at 24 months for follow-up, and, ifI am correct, in the distal pedal bypass group with the calcified group only nine patients were available at 24 months. Am I correct in saying this, and do you think that affects your analysis? Dr. Misare. Log-rank life-table analysis was used for patency analysis in this study. In the subgroup comparisons excluding primary procedures, which excluded 25 % of our initial patient data base, fewer patients were followed out to

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24 months. By using the criteria for life-table analysis set by the SVS/ISCVS, however, the SEM for all patency comparisons in this study was less than 10 percent at 2 years of follow-up. Thus our patient data maintained statistical validity at this time interval. Beyond 2 years, the statistical significance was limited by patient follow-up. Dr. M a g r u d e r C. D o n a l d s o n (Boston, Mass.). The 30-day failure rate of 1% to 2% indicates very strongly that you gentlemen know how to do this operation technically. The relatively early follow-up and a patency trend that looks a little bit worrisome hopefully will not persist. Have you learned anything from looldng at the causes of failures in this calcified group? Is there any indication of a higher incidence of causes related to the calcified anastomotic region or

run-off bed later than the 30-day period that reflects clamp injury or other issues? Dr. Misare. One thing that we did note in this series was that there appeared to be continuing graft failure in the severely calcified group, without a plateau in the life-table curve as is usually observed in vein grafts and was observed in the uncalcified group. The reasons for this trend are unclear, although a large number patients undergoing dialysis were included in the severely calcified group. These patients tend to have the worst results and may partly be responsible for this finding. The causes of the late graft failure in the calcified arteries were not analyzed in this study.

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