Laser arterial disobstructive procedures in 148 lower extremities

Laser arterial disobstructive procedures in 148 lower extremities Teruo M a t s u m o t o , M D , P h D , FACS, Takeshi Okamura, M D , and Vrajlal Rajyaguru, M D , Philadelphia, Pa. Preoperative arteriographic findings in immediate postoperative results as well as followup studies of treatment with argon and YAG lasers have been evaluated in 148 lesions found in 137 patients. Preoperative arteriography revealed a solitary lesion in 42 of 148 legs (28%) examined, and a combined lesion was found in the remaining 106 legs (72%). Incapacitating intermittent claudication, rest pain, tissue loss, or a combination of these was an indication for laser arterial reconstruction. None of the argon laser-treated lesions was treated with balloon dilatation, but since March 1988 all appropriate YAG lasertreated lesions were immediately followed by laser-assisted balloon angioplasty. The lesions in 64 of 89 legs (72%) treated by argon and 42 of 59 (71%) treated by YAG were successfully recanalized. However, successful angioplasty was performed in 44 of 89 (49%) and 34 of 59 (58%) lesions, respectively. The recanalization depended on the type of lesion (tight stenosis vs occlusion) and the length of lesion (localized vs total-length occlusion). However, the success rate of recanalization was almost the same as the success rate when both laser systems were used. Argon laser treatment proved successfial in 19 of 20 (95%) segmental occlusions in popliteal arteries, whereas YAG laser treatment proved successful in four of five (80%) short segmental (< 15 cm) occlusions of superficial femoral arteries and in 16 of 23 (70%) long segmental (>15 cm) occlusions of superficial femoral arteries. In 26 of 36 (72%) total-length occlusions of superficial femoral and popliteal arteries, recanalization was not possible (p < 0.001). Hence laser recanalization was not recommended in those cases. Severely calcified lesions are not ablated by presently available laser systems. (J VASC Sting 1989;10:169-77.)

Favorable clinical results in percutancous laser an: gioplasty for ischemic limb salvage have been reported. 1-3 Those patients had short segmental occlusions (mean length 8 cm), and in most cases (65%) the indication for the procedure was intermittent claudication. 1 In another study 4 tibial artery occlusion and lesions more than 20 cm in length were excluded. Application of argon laser in 89 advanced lesions has been evaluated to determine the indications for and limitations of laser angioplasty at this institution. ~ In this study 137 patients who had severe occlusive disease and a history of incapacitating intermittent claudication, rest pain, tissue loss, or a combination of these were evaluated. The efficacy of different laser systems has also been assessed in severe atherosclerotic occlusive arterial disease of the lower extremity. From the Department of Surgery, Hahnemann University School of Medicine, Philadelphia. Reprint requests: Teruo Matsumoto, MD, PhD, Professor and Chairman, Department of Surgery, Hahnemann University School of Medicine, Broad and Vine St., Philadelphia, PA 19102-1192.

The purpose of this study is (1) to evaluate the efficacy of argon and YAG laser treatment in occlusive arterial lesions of the lower extremity, (2) to assess the effectiveness of balloon dilatation along with laser recanalization, and (3) to report the available results of our limited follow-up study of argon and YAG laser arterial reconstruction. PATIENTS AND METHODS The patients selected included 87 men and 50 women (total 137); their ages ranged from 40 to 85 years (mean 65 years). The lesions of 148 legs were treated between April 1986 and December 1988 (Table I). Indications for procedures were incapacitating intermittent daudication (grade I) in 46 (31%), rest pain (grade II) in 67 (45%), and tissue loss (grade III) in 35 (24%) of the legs examined. Previous vascular reconstructions were noted in 43 legs (29%) at the time of admission. Preoperative arteriography was performed on all patients showing symptoms to determine the type of lesion (stenosis vs occlusion), extent of lesion (segmental vs total length), and severity of lesion (atherosclerotie vs calcified). When arteriography re169

170

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Matsumoto, Okamura, and Rajyaguru

Table I. Summary of patient data Duration of study No. of patients Men Women Age (yr) Legs Combined lesions Previous vascular surgery Indications Incapacitating intermittent claudication (grade I) Rest pain (grade II) Tissue loss (grade III)

Argon

YA G

Total

Apr. 86-Nov. 87 84 50 34 42-85 89 59 (66%) 25 (28%)

Dec. 87-Dec. 88 53 37 16 40-84 59 47 (80%) 18 (31%)

Apr. 86-Dec. 88 137 87 50 40-85 148 106 (72%) 43 (29%)

19 (21%)

27 (46%)

46 (31%)

52 (59%) 18 (20%)

15 (25%) 17 (29%)

67 (45%) 35 (24%)

Table II. Immediate operative results of argon laser No. of legs Successful angioplasty (recanalized to adequate diameter) LR + BD

Artery &graft SFA*

Profimda femoris Popliteal Infrapopliteal Graft occlusion Total

Type of lesion Segmental occlusion <15 crn I>15 cm Total-length occlusion Stenosis Segmental occlusion Stenosis Segmental occlusion Total-length occlusion Stenosis Segmental occlusion

Total 7 8 23 2 2 2 20 1 1 8 15 89

LR 6 2 0 0 0 2 19 0 0 0 15 44

(86%) (25%)

(100%) (95%)

(100%) (49%)

(LABA) 0 0 0 0 0 0 0 0 0 0 0 0

Unsuccessful angioplasty Too narrow Impossible recanalization recanalization

0 2 7 2 0 0 0 0 1 8 0 20

(25%) (30%) (100%)

(100%) (23%)

i (14%) 4 (50%) 16 (70%)l 0 2 (100%) 0 1 (5%) 1 (100%) 1 0 0 0 25 (28%)

LR, laser recanalization; BD, balloon dilation; LABA, laser-assistedballoon angioplasty. ~There was a statisticallysignificant difference of successful angioplasty between the SFA and the popliteal artery (p < 0.001). tThere was a statisticallysignificantdifference of recanalization between total-length occlusion and other lesions (p < 0.001).

vealed severe narrowing (stenosis) or complete obliteration (occlusion) or both, those cases were considered for a laser procedure. Arteriographic findings were confirmed during the procedure. Postoperative arteriography was done in all patients to evaluate the immediate success and to detect possible complications. The arteriographic findings and immediate results are summarized in Tables II, III, and IV. Preoperative arteriography revealed a solitary lesion in 42 of 148 legs (28%) and a combined lesion in the remaining 106 legs (72%). Treatment of the most appropriate (technically accessible) lesion in each leg (total of 148 lesions) was attempted to disobstruct either by argon or by YAG laser; other proximal and/or distal lesions in respective legs

were treated by balloon angioplasty or appropriate bypass surgery or both. Of the 148 legs treated with a laser 16 (11%) had stenoses, 77 (52%) had segmental occlusions, and 55 (37%) had totallength occlusions. In the latter group 36 were arterial occlusions, and 19 were graft occlusions. The total-length occlusion in this study was defined as an occlusion greater than 75% of the length of the artery. All cases were first evaluated for a percutaneous approach. Since the primary requirement for a safe and successful percutaneous approach was patency of the superficial femoral artery (SFA) at the proximal end, only six cases were considered for this approach. Passage o f a hydrophilic guidewire (Medi-tech, Inc.

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Laser arterial disobstructive procedures 171

Table III. Immediate operative results of YAG laser treatment

No. of legs Successful angioplasty (recanalized to adequate diameter) Artery &graft Common iliac artery SFA

Popliteal artery Infrapopliteal Graft occlusion Total

LR + BD (LABA)

Type of lesion

Total

LR

Segmental occlusion Stenosis Occlusion Segmental <15 cm ~15 cm Total-length Stenosis Total-length occlusion Segmental occlusion

2 9

0 2 (22%)

5 23 7 2 5 2 __4 59

1 (20%) 0 0 2 (100%) 1 (20%) 2 (100%) 3 (75%) 11 (19%)

1 (50%) 5 (56%) 3 12 0 0 2 0 0 23

(60%) (52%) (40%) (39%)

Unsuccessful angioplasty Too narrow recanalization

Impossible recanalization

1 (50%) 2 (22%) 0 5 (22%) 0 0 0 0 0 8 (13%)

1 (20%) 6 (26%) 7 (100%)~ 0

2 (40%)~ 0 1 (25%)

17 (29%)

LR, laser recanalization; BD, balloon dilation; LABA, laser-assistedballoon angioplasty. *There was a statisticallysignificant difference (p < 0.001) of recanalization between total-length and other occlusions.

Table IV. Immediate results of laser arterial reconstruction in 148 legs

No. of legs Successful angioplasty (recanalized to adequate diameter)

Type Type of lesion

of laser

Total

LR + BD (LABA)

LR

Unsuccessfulangioplasty Too narrow recanalization

Stenosis

Argon YAG

5 __11 16

2 (40%) 4 (36%) 6 (38%)

0 5 (45%) 5 (31%)

3 (60%) 2 (18%) 5 (31%)

Segmental occlusion

Argon YAG

45 32 7"---7

27 (60%) 3 (9%) 30 (39%)

0 16 (50°,6) i6 (21%)

10 (22%) 6 (19%) 16 (21%)

Argon YAG

24 12 36

0 1 1

(8%) (3%)

0 2 (17%) 2 (6°,6)

7 (29%) 0 7 (19%)

15 _ _4 19 148

15 3 18 55

(100%) (75%) (95%) (37%)

0 0 0 23 (16%)

0 0 0 28 (19%)

Total-length occlusion

Graft occlusion Total

Argon YAG

Impossible recanalization

8 (18%)

7 (22%) 15 (19%) 17 (71%) 9 (75%) 26 (72%)~ 0

1 (25%)

1 (5%) 42 (28%)

For abbreviations see Table II. ~Statistically significant difference between the success rate of total-length occlusion and that of others (p < 0.001).

Watertown, Mass.) was attempted in all cases. If the guidewire passed through the artery, only balloon angiophsty was performed, and those cases were eliminated from this study. Balloon angioplasty and balloon dilation were performed by use of a Gruentzig balloon catheter (Medi-tech, Inc., Watertown, Mass.). Successful recanalization of lesions by means of

laser alone was defined as laser recanalization. When laser recanalization created a channel of adequate diameter, it was referred to as laser angioplasty. When laser recanalization was followed by balloon dilation, it was called laser-assisted balloon angioplasty. Bypass grafting was performed parallel to the arterial lesion, from proximal end to the distal end of the lesion as needed. All procedures (laser recanalization, laser an-

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172 Matsumoto, Okamura, and Rajyaguru

Fig. 1. A, Infrapopliteal artery occlusion. B, Good distal runoff after argon laser recanalization. gioplasty, laser-assisted balloon angioplasty, and parallel bypass grafting) were collectively defined as laser arterial reconstruction. This study was based on three consecutive phases between April 1986 and December 1988. In the first phase, between April 1986 and November 1987, the argon laser (Trimedyne Inc., Santa Ana, Calif.) was exclusively used in lesions of 89 legs to evaluate its efficacy as a sole treatment in occlusive vascular disease of the lower extremity. During this period tight stenosis, various length occlusions of the SFA, deep femoral artery, popliteal artery,~ and infrapopliteal artery (tibioperoneal trunk and tibial artery), and graft occlusions were treated. Since the laser had limited energy, only smalldiameter laser tips (2 ram) were available. Consequently, the lesions of small-diameter arteries such as the popliteal artery could be recanalized by adequate blood flow (laser angioplasty) (Fig. 1). However, arteries of larger diameter such as the SFA could be recanalized, but blood flow was not adequate because of a narrow channel. Therefore later cases required parallel bypass surgery to provide adequate blood flow to the distal arteries (Table II). Since the protocol during this period was to evaluate the efficacy of laser recanalization with a laser tip, no attempt was made to combine balloon dilation with laser recanalization. In the second phase, between DeCember 1987 and February 1988, a high-energy YAG laser (Trimedyne Inc., Santa Ana, Cali£) with 2.5 m m and

3.5 m m diameter laser tips was used in SFA lesions. In spite of increased energy with these laser tips, 57% of the patients required parallel bypass surgery because ablation of plaque beyond the diameter of the laser tip was again not possible. Consequently, in the third phase, between March 1988 and December 1988, all lesions of the SFA and popliteal artery were treated b y laser-assisted balloon angioplasty. The indications for additional balloon dilation were determined intraopcratively after fluoroscopy. Balloon dilation after laser recanalization significantly improved arteriographic findings (Fig. 2). Heparin was infused (100 units/kg) during the procedure, and an anti-plate!et drug wa s given to all patients after surgery. Each arterial occlusive lesion was assessed during surgery by fluoroscopy and after surgery by arteriography. Results were divided into two categories-successful and unsuccessful angioplasty--according to immediate postoperative arteriographic findings. Recanalization that resulted in adequate luminal diameter was defined as successful angioplasty that was achieved by either laser recanalization or laserassisted balloon angioplasty. Unsuccessful angioplasty was further divided into two categories: category 1, too narrow recanalization (recanalization that did not produce adequate luminal diameter); and category 2, impossible recanalization. When argon laser was used, all lesions resulted to category 1 were treated by parallel bypass grafting. However

Volume 10 Number 2 August 1989

Laser arterial disobstructive ~rocedures 173

Fig. 2. A, Long segmental occlusion (---15 cm) of the SFA. B, Successfulangioplasty resulting ,: from laser-assisted balloon angioplasty. when YAG laser was used, parallel bypass grafting was performed in category 1 if balloon dilation proved unsuccessful. All impossible recanalizations (category 2) in both laser systems were treated by parallel bypass grafting (Figs. 3 and 4). This study was undertaken with the approval of an Institutional Review Board and the Food and Drug Administration. Informed consent was obtained from all patients in the study before the procedure. Statistical analyses were made by the chi-square test. RESULTS Analysis of immediate results of laser arterial reconstruction is shown in Fig. 4. When argon laser was used, the following resuited in successful angioplasty: 6 of 7 (86%) short segmental occlusions (<15 cm) and 2 of 8 (25%) long segmental occlusions (>-15 cm) of the SFA; and 2 of 2 (100%) stenoses and 19 of 20 (95%) segmental occlusions of the popliteal artery. All 15 grafts were reopened and luminal diameter was adequate. All stenoses (one) and segmental occlusions (eight) of infrapopliteal arteries were recanalizcd, but adequate diameter was not achieved. Essentially, laser recanalization was attempted in all described lesions, and laser-assisted balloon angioplasty was not used. In occluded popliteal arteries 19 of 20 (95%) laser recanalizations were successfully converted into laser

angioplasties. None of the total-length occlusions of SEAs and popliteal arteries resulted in successful angioplasty. The successful recanalization rate was 72% (64/89) and the successful angioplasty rate was 49% (44/89). A statistically significant difference was found between successful angioplasty of popliteal arteries and SFAs (p < 0.001). A statistically significant difference in successful recanalizations was also found between total-length occlusions and other lesions (p < 0.001) (Table II). When the YAG laser was used, five of nine (56%) stenoses, three of five (60%) short segmental occlusions (<15 cm), and 12 of 23 (52%) long segmental occlusions• (---i5 cm) of.the SEA had a successful laser-assisted balloon angioplasty. Laser recanalization resulted in successful angioplasty in three lesions (two in stenoses and one in a short segmental occlusion) of SFAs. Successful laser angioplasty (adequate luminal diameter) was achieved in two of two (100%) stenoses, one of five (20%) total-length occlusions of the popliteal artery, t w o o f two (100%) segmental occlusions of the infrapopliteal artery, and three of four (75•%) graft occlusions. Successful angioplasty was not achieved in any of SEAs and in two of five (40%) of popliteal arteries with totallength occlusion. The successful recanalization rate was 71% (42/59), and thcsuccessful angioplasty rate was 58% (34/59). Laser recanalization was successfully used in 11 of 59 (!9%) and laser-assisted balloon angioplasty was used in 23 of 59 (39%) lesions.

Journal of VASCULAR SURGERY

174 ¢Vlatsumoto,Okamura, and Rajyaguru

Fig. 3. A, Total-length occlusion of the SFA and stenosis of the popliteal artery (combined lesion). B, Total-length occlusion of SFA and stenosis of the popliteal artery treated by parallel bypass. Table V. Efficacy of balloon dilation followed by successful laser recanalization No. of lesions Recanalization Type of laser

Balloon dilation

Total

Argon

With BD Without BD (LR) Total With BD (LABA) Without BD (LR) Total

0 64 64 25 17 42

YAG

Adequate diameter (successful angioplasty) 0 44 44 23 11 34

(69%)~ (69%) (92%)a (65%) (81%)

Inadequate diameter (unsuccessful antioplacty) 0 20 (31%) 20 (31%) 2 (8%) 6(35~ 8 (19%)

For abbreviations see Table II. ~Statisticallysignificantdifferenceof successfulangioplasty between argon laser recanalizationand YAG laser-assistedballoon angioplasty

(p < 0.05). A statistically significant difference between successful recanalization of total-length occlusion and all other lesions was found (p < 0.001) (Table III). In this study angioplasty was successful in 78 of 148 (53%) lesions. Laser recanalization and laserassisted balloon angioplasty were used in 55 (37%) and 23 (16%) of these lesions, respectively. None of the total-length occlusions had adequate diameter after recanalization by argon laser, and three of 12 (25%) total-length occlusions were recanalized to adequate diameter by YAG. In 15 of 15 (100%) and three of four (75%) graft occlusions adequate diameter was achieved by recanalization with argon and

YAG, respectively. O f 148 lesions 28 (19%) did not have adequate diameter after recanalization, and 42 (28%) were impossible to recanalize. A statistically significant difference was determined between recanalization of the total-length occlusions and others (p < 0.001) (Table IV). In 44 of 64 (69%) lesions successful angioplasty was achieved with argon laser recanalization. When YAG laser-assisted balloon angioplasty was used, the success rate was 92% (23/25); however, six of 17 (35%) recanalized lesions had inadequate diameter and were not treated with balloon dilation. A statistically significant difference was found between suc-

Volume10 Number2 August1.989

Laser arterial disobstructive procedures 175

Tota11481esions I !

, I

!

YAG*2

treated 89 I

treated 59 I

I

Impossible

Successful recanalization 64

recanalization 25

Inadequate diameter 20

!

Impossible recanalization , 17 I

Adequate

recanalization 42 I

diameter 44

diameter 31 I

I Noballoon*a dilatation 6

I

diameter 11

I

Balloon*4

dilatation 25

I

I

2

Adequate diameter 23

Inadequate I diameter Bypass surgery

I

Adequate

Inadequate

I

I [

Bypass surgery

Bypass surgery

I

Bypass surgery

Bypass surgery

Fig. 4. Analysis of immediate results of laser arterial reconstruction: *i, April 1986 to November 1987; *2, December 1987 to December 1988; *3, December 1987 to February 1988; *4, March 1988 to December 1988.

cessful angioplasty without balloon dilation (argon laser recanalization) and with balloon dilation (YAG laser-assisted balloon angioplasty) (p < 0.05) (Table V, Fig. 4). Calcification was divided into categories A and B depending on intraoperative appearance and consistency of the arterial wall. Category A included red, rather swollen, and soft-textured arteries with some evidence of limited lumen (soft atherosclerosis). Category B included pale, shrunken, and hard-textured (cordlike) arteries without any evidence of lumen (hard atherosclerosis). In arteries in category A, recanalization was successful in eight of 11 (73%) totallength occlusions. However, in arteries in B, recanalization was achieved in only two of 25 (8%) totallength occlusions (p < 0.001) (Table VI). Lesions having an inadequate luminal diameter after argon laser treatment had bypass grafting; whereas when YAG was used, treatment of the lesions was first attempted by balloon dilation and if balloon dilation failed, parallel bypass grafting was performed. However, all lesions that could not be recanalized were treated by parallel bypass grafting in both laser systems. Nine perforations occurred during this study;

seven occurred in SFAs, one occurred in popliteal artery, and one occurred in a graft. All occurred when the YAG laser was used. In the SFAs four perforations occurred in total-length occlusions, two occurred in long segmental occlusions (-> 15 cm), and one occurred in a short segmental occlusion (<15 cm). All perforations were detected promptly and treated by appropriate bypass surgery. In the present study follow-ups were performed on 72 of 78 (92%) legs for 15 days to 24 months. Four of 25 (16%) patients undergoing argon laser recanalization required amputation during the 3- to 19-month follow-up period. All seven patients undergoing YAG laser recanalization had patent arteries during the 1- to 6-month follow-up period. Nineteen of 22 (86%) patients undergoing YAG laser-assisted balloon angioplasty had patent arteries, and three (14%) of the patients required amputation during the 15-day to 5-month follow-up period. All 18 grafts were patent during the 1- to 24-month followup period (Table VII). DISCUSSION

Laser treatment of occlusive vascular lesions of the lower extremities is a new and developing tech-

Journalof VASCULAR SURGERY

176 Matsumoto, Okamura, and Rajyaguru

Table VI. Immediate operative results of total-length occlusion of SFA and popliteal artery (PA) in relation to degree of calcification No. oflegs

Degree of calcification

Artery

Soft atherosclerosis with some evidence of limited arterial lumen~

SFA PA

Hard atherosclerosis without any evidence of lumen~

SFA PA

Total

Successful angioplasty (recanalized to adequate diameter)

Argon YAG Argon YAG

7 1 0 __3 11

Argon YAG Argon YAG

16 6 1 2 25

Type of laser

Unsuccessful angioplasty Too narrow recanalization

Impossible recanalization

0 0 0 3, (100%) 3 (27%)

5 (71%)

2 (29%) 1 (100%) 0 0 3 (27%)

0 0 0 0 0

2 (13%) 0 0

0 0 5 (46%)

2 (8%)

14 (87%) 6 (100%) 1 (100%) 2 (100%) 23 (92%)

*There was a statisticallysignificant difference of recanalization rate between groups.

Table VII. Follow-up results of Argon and YAG laser treatment Laser Argon LR YAG LR YAG LABA Total

Lesion

Total legs

Follow-up period (mo)

Artery Graft Artery Graft Artery

25 15 7 3 __22 72

3-19 1-24 1-6 1-4 1/2-5 1/2-24

No. patent arteries 21 15 7 3 19 65

(84%) (100%) (100%) (100%) (86%) (90%)

No. amputations 4 (16%) 0 0 0 3 (14%) 7 (10%)

For abbreviations see Table II.

nique. In this study the immediate and limited follow-up results of two different laser systems, argon and YAG, have been assessed in 148 lesions in lo~¢er extremities. In the argon laser system the small laser tip with the aperture at the apex was used in this study, in the hope that direct laser energy ablates atheromatous plaque. The laser energy emerges through the small aperture in the form of a beam and presumably strikes the lesion directly. However, the heat of the laser energy in the metal tip appears to facilitate recanalization. Because of energy limitation, only a small-diameter laser tip (2 ram) could be optimally activated by argon laser. In the "more powerful YAG laser system the laser energy was used for thermal activation of the laser tip. Consequently, tips of larger diameter (2.5, 3.5, 4.2 nun, and larger) can be optimally activated. Unlike the argon energy, the YAG laser energy was principally used indirectly to heat the laser tip in this study. Although the rate of successful recanalization is almost the same in both laser systems, the rate of successful angioplasty is 9%

greater with the YAG laser system. This might be due to the higher energy level of the system and balloon dilation after the YAG laser recanalization. Previous studies by other investigators show " high success rate (93%). 13 However, in this study the rate of successful recanalization is 72% and the rate of successful angioplasty is 53%. The reasons for this are (1) the present study focused on severe atherosclerotic arterial disease, with 72% combined lesions and 37% total-length occlusions, (2) 69% of the patients in the present study had a history of rest pain (grade II) or tissue loss (grade III), (3) mean arterial occlusion was 27 cm in presented cases, and (4) 29% of the legs in this study had evidence of previous vascular surgery at the time of patient adnUSSlOn;

A reasonable success rate was achieved for recanalization of segmental occlusions and tight stenoses. However, very few (8%) of the total-length occlusions could be recanalized. Efforts to recanlize totallength occlusions resulted in five perforations (fou(

Volume 10 Number 2 August 1989

SFAs and one popliteal artery). Therefore, laser recanalization should not be performed in total-length occlusions of SFAs or popliteal arteries at this time. At present, conventional arterial reconstructive bypass is the treatment of choice in these cases. The argon laser was used exclusively between April 1986 and November 1987. Since the energy level was low (12 W), only a small-diameter laser tip (2 mm) could be optimally activated. Therefore the argon laser remains effective in treating short segmental occlusions of small-diameter arteries, such as popliteal arteries and infrapopliteal arteries (Fig. 1). Argon laser recanalization in lesions of popliteal arteries facilitates conversion of the below-knee to the the above-knee bypass, which eliminates the absolute need to use saphenous vein. In SFAs a substantial number of cases required parallel bypass grafting because of limited energy and a smaller laser tip and because balloon dilation was not combined with argon laser recanalization, in keeping with our protocol. If balloon dilation had been combined with the argon laser treatment, a higher rate of successful angioplasty would have been achieved. The YAG laser was used between December 1987 and December 1988 on lesions o n 5 9 legs. This system has a much higher energy level (maximum of 60 W); therefore a laser tip of greater diameter could be activated. Because these bigger laser tips may ere, ate a larger opening in bigger-diameter arteries such as SFAs, an additional balloon angioplasty may not be necessary. In addition, the YAG system is just as efficacious in small-diameter arteries as the argon laser ~recanalization. Therefore we started using, the YAG laser system as soon as the FDA approved it in December 1987. From December 1987 to February 1988, the YAG laser was used with tips of larger diameter even though 57% of the lesions of SFAs required parallel bypass surgery. Therefore since March 1988, we have not used laser recanalization as a sole therapy in large arteries, and all lesions have been treated by laserassisted balloon angioplasty. Consequently, recanalization followed by balloon dilatation markedly improved arteriographic findings in large-diameter arteries such as the SFA (Fig. 2), and in a substantial number of cases parallel bypass surgery was not required (Fig, 4). Thus balloon dilation may prove useful and cost-effective in decreasing length of hos-

Laser arterial disobstructiveprocedures 177

pitalization and minimizing surgical intervention. However, the results of laser-assisted balloon angioplasty may be determined by the success of balloon dilation rather than by the type of laser alone. Longterm results are not yet available. The degree of calcification depends mainly on the severity of atherosclerosis. A previous study shows that in severe calcification, laser recanalization was impossible. 6 Severe atherosclerotic lesions usually occlude the total length of the artery. In this study 55 total-length occlusions treated with argon or YAG laser were evaluated. Our results indicate that laser arterial reconstruction is not the treatment of choice in total-length occlusions. Many physicians believe that although laser energy directly or indirectly ablates the atheromatous plaque, the optimum energy level is not adequate to evaporate severely calcified lesions. The follow-up results of the present study showed that seven patients (10%) required amputation from 15 days to 24 months after surgery. Since 72% of the legs had combined lesions and 29% of the legs had previous vascular surgery at other institutions, the follow-up resuks are not based solely on laser therapy. Since only a limited follow-up was done, longterm evaluation must be performed before laser dis, obstruction is used routinely.In the future, develop: ment of a graduated laser tip correlated with arterial diameter would facilitate Successful laser angioplasty. REFERENCES 1. Cumberland DC, Tayler DI, Welsh CL, et al. Percutaneous laser thermal angioplasty: initial clinical results with a laser probe in total peripheral artery occlusions, Lancet 1986; 2:I457-9. 2. Sanborn TA, Greenfield AJ, Guben JK, Menzoian JO, LoGerfo FW. Human percutaneous and intraoperative laser thermal angioplasty: initial clinical results as an adjunct to balloon angioplasty. J VAsc.SuRG 1987;5:83-7. 3. Fleischer HL, Thompson BW, McCowan TC, Ferris EJ, Reifsteck JE, Barnes RW. Human percutaneous laser angioplasry. Patient selection criteria and early results. Am J" Surg 1987; I54:666-9. 4. Seeger JM, Abela GS, Silverman SH, Jablonski SK. Initial results of laser recanalization in lower extremity arterial reconstruction. J VAsc SURG 1989;9:i0-7. 5. Matsumoto T , K0yanagi N, Yang Y, DuPree J. Laser arterial recanalization in reconstructive vascular surgery. Contemporary Surg 1988;33:11-9: 6. Yang Y, Hashizume M, Arbuntina D, Milewski LF, DuPree J, Matsumoto T. Argon laser angioplasty with a laser probe. J VAsc SURG 1987;6:60-5. %