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Follow-up of Conventional Angioplasty versus Laser Thermal Angioplasty for Total Femoropopliteal Artery Occlusions: Results of a Randomized Trial
Vascular Therapy
Follow-up of Conventional Angioplasty versus Laser Thermal Angioplasty for Total Femoropopliteal Artery Occlusions: Results of a Randomized Trial! Anna-Maria Belli, FRCR David C. Cumberland, FRCR, FRCP Anne E. Procter, FRCR Christopher L. Welsh, FRCS
Index terms: Arteries, femoral, 92.128 • Arteries, laser angioplasty, 92.128 • Arteries, popliteal, 924.128 • Arteries, stenosis or obstruction, 924.721, 92.721 • Arteries, transluminal angioplasty, 92.128 • Lasers JVIR 1991; 2:485-488 Abbreviations: Nd:YAG = neodymium: yttrium-aluminum-garnet, PTA = percutaneous transluminal angioplasty
1 From the Departments of Radiology (AM.B., D.C.C., AE.P.) and Surgery (C.L.W.J, Northern General Hospital, Sheffield, England. Received June 5, 1991; revision requested July 22; revision received August 19; accepted September 3. Address reprint requests to AM.B., Department of Radiology, Hammersmith Hospital, Du Cane Rd, London W12 ONN, England.
"SCVIR,1991
Sixty-eight patients with 68 femoropopliteal occlusions were entered into a randomized trial of conventional guide-wire and catheter percutaneous angioplasty versus laser thermal angioplasty. Thirty-four occlusions were randomized to conventional angioplasty and 34 to laser thermal angioplasty. Mter successful recanalization and balloon dilation, the patients were followed up for 1 year. Follow-up consisted of obtaining measurements of the ankle-arm indexes at 1, 3, 6, and 12 months. The increase in the mean resting ankle-arm index 1 year after conventional angioplasty (0.26) was greater than that after laser angioplasty (0.12). At I-year follow-up, the cumulative success rate was 47% for patients treated with conventional angioplasty versus 39% for those treated with laser angioplasty. Statistical analysis showed no significant difference in clinical success between the two treatment groups. LASER systems of various types are being evaluated throughout the world, and optimistic reports appear in the literature claiming possible improved performance (1-4), but there is very little objective evidence in the form of randomized trials. In some cases the devices are still undergoing modification and preliminary clinical assessment, and the scene is not yet set for a randomized trial. However, some devices, such as sapphire contact probes and "hottip" probes with continuous-wave laser sources, have been extensively used clinically. Randomized trials are currently underway to assess their clinical utility (5-7). Such a trial has been performed at our institution. The primary success rates of conventional techniques and the hybrid laser thermal probe in crossing total peripheral artery occlusions have been reported already (8), and no statistically different recanalization rates were seen, although immediate crossover to the alternative method improved the results. In this article, we report the clinical success of such treatments up to 1 year after the procedure.
PATIENTS AND METHODS Between October 1988 and May 1990,68 patients with 68 total occlusions in the femoropopliteal artery were entered into the trial. All patients were considered suitable candidates for percutaneous transluminal angioplasty (PTA) via an ipsilateral femoral artery puncture. Patients were randomized to one form of treatment by blind selection of a premarked card from a box. Thirty-four were randomized to laser treatment and 34 to conventional treatment. A 2.5-mm hybrid laser probe (Spectraprobe PLR; Trimedyne, Santa Ana, Calif), which does not pass over a guide wire, was used in all cases randomized to laser treatment. If the occlusion was successfully recanalized, balloon dilation was performed with use of a balloon of approximately the same diameter as the artery. Between October 1988 and May 1989, the laser source was a continuous-wave argon laser generator (Cooper Laser Sonics, Santa Clara, Calif); from June 1989 to May 1990, the source was a continuous-
485
486 • Journal of Vascular and Interventional Radiology November 1991
wave neodymium: yttrium-aluminum-garnet (Nd: YAG) generator (Cardiolase 4000; Trimedyne). In both cases, 10-12 W oflaser energy was used to heat the probe. If the case was randomized to conventional treatment, a variety of guide wires were used, depending on the operator's preference (8). Once crossed, the occlusion was dilated with a 7-F balloon catheter. Resting Doppler ankle-arm indexes were measured at follow-up 1, 3, 6, and 12 months after PTA. Clinical success was defined as relief of symptoms and an increase in Doppler ankle-arm index of at least 0.15. Balloon dilation was performed as the final procedure in all cases by using a standard technique with routine intraarterial administration of 3,000 IV of heparin prior to balloon dilation.
RESULTS The length of femoropopliteal occlusions in the laser and conventionally treated groups were 1-15 cm (mean, 6 cm) and 1-25 cm (mean, 8 cm), respectively. Failure to cross the occlusion and proceed to balloon dilation occurred in six cases: three in the laser group and three in the conventional treatment group. The attempt at PTA did not worsen the condition of any of these patients. All of these patients are included in the final analysis. Immediate crossover to the alternative therapy was allowed in the trial; however, this could be performed in few cases. Failure to recanalize an occlusion with a guide wire and catheter was not readily accepted; often dissection had occurred, and the lumen could not be reentered with the wire. In these circumstances, the energized laser probe could not reasonably be expected to be successful. In one case, when conventional recanalization failed and dissection had not occurred, the energized laser probe successfully recanalized the occlusion. The laser probe was found to have very useful me-
chanical properties and helped reenter the true arterial lumen even after extensive dissection in five cases (8). Similarly, the guide wire was able to successfully recross an occlusion in three cases when use of the laser probe resulted in dissection. The two treatment groups were comparable for sex, age range, severity of symptoms, and risk factors such as diabetes mellitus and smoking (Table 1). The cumulative rates of clinical success for femoropopliteal occlusions are shown in Table 2. A number of patients in each group were lost to follow-up at 6 months and 1 year, despite requests for them to return to the vascular laboratory. At 6 months, eight patients (24%) in the conventional group and four (12%) in the laser group were lost to follow-up; at 1 year, the numbers rose to 10 (29%) and eight (24%) in the conventional and laser groups, respectively. The Kaplan-Meier survival curve (Fig) shows a steady drop in clinical success throughout the year in both groups, with poorer results in the laser group. Analysis of the results (log rank test, l) showed no statistical difference between the two treatment groups at any time during the follow-up period (l = 0.06, df = 1, P = .81). The mean Doppler anklearm indexes were 0.51 before and 0.77 1 year after conventional PTA versus 0.64 before and 0.761 year after laser angioplasty; therefore, there was an increase of 0.26 versus 0.12 after conventional and laser angioplasty, respectively. Complications included a groin abscess secondary to hematoma in one patient. In three cases (two in the conventional group, and one in the laser group), a small embolus was noted in the calf vessels on the angiogram obtained after PTA. However, in no case did this obstruct flow or cause clinical symptoms. Spasm was induced in four patients (two in the laser group and two in the conventional group), requiring treatment with antispasmodics. Hematoma formation, dissection, and perforation were not considered
Table 1 Summary of Patient Data ConvenCharacteristic tional Laser Sex 21 Male 24 13 Female 10 Symptoms Intermittent claudication 24 24 Rest ischemia 10 10 Occlusion length (cm) 1-25 1-15 Range Mean 8 6 Runoff vessels 25 27 2-3 9 ~1 7 Risk factors IDDM 4 2 NIDDM 5 1 Former smoker 28 31 Still smoking 4 10 Note.-IDDM = insulin-dependent diabetes mellitus, NIDDM = non-insulin-dependent diabetes mellitus.
Table 2 Cumulative Success Rates (%) for Conventional and Laser Thermal Angioplasty Time (mo) after Angioplasty Immediately 1
Conventional 88 82
Laser 88 79
3 6 12
72 56 47
56 42 39
% Clinical Success
100
;g
!?.~ :0
75
e0-
50
.~
25
ctl .0
ro>
Conventional
Laser
:::J (f)
0 0
3
6
12
time (months)
Kaplan-Meier curve of clinical success in the two treatment groups.
Belli et al • 487 Volume 2 Number 4
significant complications unless they necessitated prolonged hospital stay or operative intervention or worsened the patient's clinical grade. Apart from abscess formation in one groin hematoma, there were no significant complications.
DISCUSSION Over the past few years there has been an explosion of interest in new percutaneous adjunctive techniques to conventional balloon angioplasty. Although these new devices are aimed at further improving the results of balloon dilation, there has been very little objective evidence that they achieve their aims. There has been a call for randomized trials to assess these devices before they are taken up more widely (9). On the whole, they are expensive, adding considerably to the cost of percutaneous balloon dilation, which has gained popularity partly because of its low cost compared with surgery (10). To our knowledge, there have been three reports of results of a randomized trial in which the "hot-tip" probe was used (5,6,8). A randomized trial is also underway to assess conventional angioplasty with the Nd: YAG laser and excimer laser-assisted angioplasty (7). So far the results of the trials with the hot-tip probe confer no advantage to laser thermal angioplasty when compared with conventional PTA, although a combination of the two techniques may increase primary success in crossing femoropopliteal occlusions (8). In the article by Jeans et al (5) patency at 1 month was 52% and 57% for the laser and conventional groups, respectively. In this article, we compared the I-year results ofthe two treatment methods. The results in the group treated with laser angioplasty are not as good as those in the group treated with conventional PTA. Cumulative clinical success at 1 year was 47% in those treated with conventional PTA and 39% for those treated with laser
thermal angioplasty (Table 2). The results are, however, not statistically significant (log rank test, l = 0.06). Also the increase in mean resting Doppler ankle-arm indexes following conventional PTA was greater (0.26) than that following laser thermal angioplasty (0.12). However, there are many limitations to this trial. The number ofpatients recruited was small (n = 68). Follow-up of these patients was not ideal in that we were unable to perform angiography at 1 year to assess whether improvement of symptoms was due to patency of the treated segment or collateral formation. Similarly we were unable to distinguish recurrence of symptoms due to disease at the PTA site or elsewhere. This was due to inadequate funding and facilities. For the same reasons, duplex ultrasound, which would depict patency or recurrence at the angioplasty site, was not used for follow-up. This study therefore does not assess patency of the treated segment but does assess clinical success at 1 year. In addition, many patients did not return for follow-up assessment. Two patients emigrated, and two other patients moved from Sheffield without leaving a forwarding address. Three patients died during follow-up: one following a traffic accident and two from cerebrovascular accidents. Attempts were not made to interview patients by telephone. Many patients were referred from outlying hospitals and preferred to return there for follow-up. Despite good intentions, compliance was low. In all, 29% of patients in the conventional group and 24% in the laser group were lost to follow-up by 1 year. Despite these criticisms, the two groups of patients are similar both in patient characteristics and follow-up Doppler ankle-arm indexes. Our results do not show any advantage in using laser thermal angioplasty with regard to clinical success. Balloon dilation remains a necessary part of the laser procedure, and this may be a limiting factor in improvement of patency.
In conclusion, the laser probe (Spectraprobe PLR) may increase the primary success rate and be helpful in recanalizing occlusions in which conventional techniques have failed, even if only used as a mechanical tool (11), but it does not confer any advantage in clinical success. This may be due to the fact that balloon dilation remains a necessary part of the procedure to produce a definitive lumen because there is insufficient ablation of obstructing material by the laser. New laser devices are being produced in an attempt to allow more selective ablation of atheroma and produce larger channels by using a diverging beam oflight (3,12,13). Reports oflaser therapy without concomitant balloon dilation are in the preliminary stages. Once they are past the stage of initial evaluation, these should also undergo testing by means of randomized trials, preferably with angiographic follow-up to assess the patency of the treated segment. Acknowledgments: We thank Clare Wales for her invaluable help in organizing follow-up of the patients, and Sally Grant for typing the manuscript. References 1. Sanborn TA, Cumberland DC, Greenfield AJ, Welsh CL, Guben JK. Percutaneous laser thermal angioplasty: initial results and I-year follow-up in 129 femoropopliteallesions. Radiology 1988; 168:121-125. 2. Michaels JA, Goss FW, Shaw P, et al. Laser angioplasty with a pulsed Nd: YAG laser: early clinical experience. Br J Surg 1989; 76:921-924. 3. Murray A, Mitchell DC, Grasty M, Wood RFM, Edwards DH, Basu R. Peripheral laser angioplasty with pulsed dye laser and ball-tipped optical fibres. Lancet 1989; 1471-1474. 4. Lammer J, Pilger E, Karnel F, et al. Laser angioplasty: results of a prospective multicenter study at 3-year follow-up. Radiology 1991; 178:335337. 5. Jeans WD, Murphy P, Hughes AO, Horrocks M, Baird RN. Randomised trial of laser-assisted passage through occluded femoro-popliteal arteries. Br J Radioll990; 63:19-21.
488 • Journal of Vascular and Interventional Radiology November 1991
6.
Spies JB, LeQuire MR, Brantley SD, Williams JE, Beckett WC, Mills JL. Comparison of balloon angioplasty and laser thermal angioplasty in the treatment of femoropopliteal atherosclerotic disease: initial results of a prospective randomized trial-work in progress. JVIR 1990; 1:39-42. 7. Lammer J. Recanalization of arteriosclerotic occlusions with exeimer laser, Nd-YAG laser, or guide wire: preliminary report of a randomized trial (abstr). Radiology 1989; 173(P): 387. 8. Belli AM, Cumberland DC, Procter AE, Welsh CL. Total peripheral
artery occlusions: conventional versus laser thermal recanalization with a hybrid probe in percutaneous angioplasty-results of a randomized trial. Radiology 1991; 181:5760. 9. McLean GK, Burke DR, Marinelli DL. Comment on the clinical appropriateness of an emerging technology (editorial). Radiology 1989; 172:941-942. 10. Anderson JB, Wolinski AP, Wells IP, Wilkins DC, Bliss BP. The impact of percutaneous transluminal angioplasty on the management of peripheral vascular disease. Br J Surg 1986; 73:17-19.
11. Belli AM, Procter AE, Cumberland DC. Peripheral vascular occlusions: mechanical recanalization with a metal laser probe after guide wire dissection. Radiology 1990; 176:539-541. 12. Litvack F, Grundfest WS, Adler L. Percutaneous exeimer-Iaser and exeimer-laser-assisted angioplasty of the lower extremities: results of initial clinical trial. Radiology 1989; 172:331-335. 13. Leon MB, Almagor Y, Bartorelli AL, et al. Fluorescence-guided laserassisted balloon angioplasty in patients with femoropopliteal occlusions. Circulation 1990; 81:143-155.
Follow-up of Conventional Angioplasty versus Laser Thermal Angioplasty for Total Femoropopliteal Artery Occlusions: Results of a Randomized Trial! Anna-Maria Belli, FRCR David C. Cumberland, FRCR, FRCP Anne E. Procter, FRCR Christopher L. Welsh, FRCS
Index terms: Arteries, femoral, 92.128 • Arteries, laser angioplasty, 92.128 • Arteries, popliteal, 924.128 • Arteries, stenosis or obstruction, 924.721, 92.721 • Arteries, transluminal angioplasty, 92.128 • Lasers JVIR 1991; 2:485-488 Abbreviations: Nd:YAG = neodymium: yttrium-aluminum-garnet, PTA = percutaneous transluminal angioplasty
1 From the Departments of Radiology (AM.B., D.C.C., AE.P.) and Surgery (C.L.W.J, Northern General Hospital, Sheffield, England. Received June 5, 1991; revision requested July 22; revision received August 19; accepted September 3. Address reprint requests to AM.B., Department of Radiology, Hammersmith Hospital, Du Cane Rd, London W12 ONN, England.
"SCVIR,1991
Sixty-eight patients with 68 femoropopliteal occlusions were entered into a randomized trial of conventional guide-wire and catheter percutaneous angioplasty versus laser thermal angioplasty. Thirty-four occlusions were randomized to conventional angioplasty and 34 to laser thermal angioplasty. Mter successful recanalization and balloon dilation, the patients were followed up for 1 year. Follow-up consisted of obtaining measurements of the ankle-arm indexes at 1, 3, 6, and 12 months. The increase in the mean resting ankle-arm index 1 year after conventional angioplasty (0.26) was greater than that after laser angioplasty (0.12). At I-year follow-up, the cumulative success rate was 47% for patients treated with conventional angioplasty versus 39% for those treated with laser angioplasty. Statistical analysis showed no significant difference in clinical success between the two treatment groups. LASER systems of various types are being evaluated throughout the world, and optimistic reports appear in the literature claiming possible improved performance (1-4), but there is very little objective evidence in the form of randomized trials. In some cases the devices are still undergoing modification and preliminary clinical assessment, and the scene is not yet set for a randomized trial. However, some devices, such as sapphire contact probes and "hottip" probes with continuous-wave laser sources, have been extensively used clinically. Randomized trials are currently underway to assess their clinical utility (5-7). Such a trial has been performed at our institution. The primary success rates of conventional techniques and the hybrid laser thermal probe in crossing total peripheral artery occlusions have been reported already (8), and no statistically different recanalization rates were seen, although immediate crossover to the alternative method improved the results. In this article, we report the clinical success of such treatments up to 1 year after the procedure.
PATIENTS AND METHODS Between October 1988 and May 1990,68 patients with 68 total occlusions in the femoropopliteal artery were entered into the trial. All patients were considered suitable candidates for percutaneous transluminal angioplasty (PTA) via an ipsilateral femoral artery puncture. Patients were randomized to one form of treatment by blind selection of a premarked card from a box. Thirty-four were randomized to laser treatment and 34 to conventional treatment. A 2.5-mm hybrid laser probe (Spectraprobe PLR; Trimedyne, Santa Ana, Calif), which does not pass over a guide wire, was used in all cases randomized to laser treatment. If the occlusion was successfully recanalized, balloon dilation was performed with use of a balloon of approximately the same diameter as the artery. Between October 1988 and May 1989, the laser source was a continuous-wave argon laser generator (Cooper Laser Sonics, Santa Clara, Calif); from June 1989 to May 1990, the source was a continuous-
485
486 • Journal of Vascular and Interventional Radiology November 1991
wave neodymium: yttrium-aluminum-garnet (Nd: YAG) generator (Cardiolase 4000; Trimedyne). In both cases, 10-12 W oflaser energy was used to heat the probe. If the case was randomized to conventional treatment, a variety of guide wires were used, depending on the operator's preference (8). Once crossed, the occlusion was dilated with a 7-F balloon catheter. Resting Doppler ankle-arm indexes were measured at follow-up 1, 3, 6, and 12 months after PTA. Clinical success was defined as relief of symptoms and an increase in Doppler ankle-arm index of at least 0.15. Balloon dilation was performed as the final procedure in all cases by using a standard technique with routine intraarterial administration of 3,000 IV of heparin prior to balloon dilation.
RESULTS The length of femoropopliteal occlusions in the laser and conventionally treated groups were 1-15 cm (mean, 6 cm) and 1-25 cm (mean, 8 cm), respectively. Failure to cross the occlusion and proceed to balloon dilation occurred in six cases: three in the laser group and three in the conventional treatment group. The attempt at PTA did not worsen the condition of any of these patients. All of these patients are included in the final analysis. Immediate crossover to the alternative therapy was allowed in the trial; however, this could be performed in few cases. Failure to recanalize an occlusion with a guide wire and catheter was not readily accepted; often dissection had occurred, and the lumen could not be reentered with the wire. In these circumstances, the energized laser probe could not reasonably be expected to be successful. In one case, when conventional recanalization failed and dissection had not occurred, the energized laser probe successfully recanalized the occlusion. The laser probe was found to have very useful me-
chanical properties and helped reenter the true arterial lumen even after extensive dissection in five cases (8). Similarly, the guide wire was able to successfully recross an occlusion in three cases when use of the laser probe resulted in dissection. The two treatment groups were comparable for sex, age range, severity of symptoms, and risk factors such as diabetes mellitus and smoking (Table 1). The cumulative rates of clinical success for femoropopliteal occlusions are shown in Table 2. A number of patients in each group were lost to follow-up at 6 months and 1 year, despite requests for them to return to the vascular laboratory. At 6 months, eight patients (24%) in the conventional group and four (12%) in the laser group were lost to follow-up; at 1 year, the numbers rose to 10 (29%) and eight (24%) in the conventional and laser groups, respectively. The Kaplan-Meier survival curve (Fig) shows a steady drop in clinical success throughout the year in both groups, with poorer results in the laser group. Analysis of the results (log rank test, l) showed no statistical difference between the two treatment groups at any time during the follow-up period (l = 0.06, df = 1, P = .81). The mean Doppler anklearm indexes were 0.51 before and 0.77 1 year after conventional PTA versus 0.64 before and 0.761 year after laser angioplasty; therefore, there was an increase of 0.26 versus 0.12 after conventional and laser angioplasty, respectively. Complications included a groin abscess secondary to hematoma in one patient. In three cases (two in the conventional group, and one in the laser group), a small embolus was noted in the calf vessels on the angiogram obtained after PTA. However, in no case did this obstruct flow or cause clinical symptoms. Spasm was induced in four patients (two in the laser group and two in the conventional group), requiring treatment with antispasmodics. Hematoma formation, dissection, and perforation were not considered
Table 1 Summary of Patient Data ConvenCharacteristic tional Laser Sex 21 Male 24 13 Female 10 Symptoms Intermittent claudication 24 24 Rest ischemia 10 10 Occlusion length (cm) 1-25 1-15 Range Mean 8 6 Runoff vessels 25 27 2-3 9 ~1 7 Risk factors IDDM 4 2 NIDDM 5 1 Former smoker 28 31 Still smoking 4 10 Note.-IDDM = insulin-dependent diabetes mellitus, NIDDM = non-insulin-dependent diabetes mellitus.
Table 2 Cumulative Success Rates (%) for Conventional and Laser Thermal Angioplasty Time (mo) after Angioplasty Immediately 1
Conventional 88 82
Laser 88 79
3 6 12
72 56 47
56 42 39
% Clinical Success
100
;g
!?.~ :0
75
e0-
50
.~
25
ctl .0
ro>
Conventional
Laser
:::J (f)
0 0
3
6
12
time (months)
Kaplan-Meier curve of clinical success in the two treatment groups.
Belli et al • 487 Volume 2 Number 4
significant complications unless they necessitated prolonged hospital stay or operative intervention or worsened the patient's clinical grade. Apart from abscess formation in one groin hematoma, there were no significant complications.
DISCUSSION Over the past few years there has been an explosion of interest in new percutaneous adjunctive techniques to conventional balloon angioplasty. Although these new devices are aimed at further improving the results of balloon dilation, there has been very little objective evidence that they achieve their aims. There has been a call for randomized trials to assess these devices before they are taken up more widely (9). On the whole, they are expensive, adding considerably to the cost of percutaneous balloon dilation, which has gained popularity partly because of its low cost compared with surgery (10). To our knowledge, there have been three reports of results of a randomized trial in which the "hot-tip" probe was used (5,6,8). A randomized trial is also underway to assess conventional angioplasty with the Nd: YAG laser and excimer laser-assisted angioplasty (7). So far the results of the trials with the hot-tip probe confer no advantage to laser thermal angioplasty when compared with conventional PTA, although a combination of the two techniques may increase primary success in crossing femoropopliteal occlusions (8). In the article by Jeans et al (5) patency at 1 month was 52% and 57% for the laser and conventional groups, respectively. In this article, we compared the I-year results ofthe two treatment methods. The results in the group treated with laser angioplasty are not as good as those in the group treated with conventional PTA. Cumulative clinical success at 1 year was 47% in those treated with conventional PTA and 39% for those treated with laser
thermal angioplasty (Table 2). The results are, however, not statistically significant (log rank test, l = 0.06). Also the increase in mean resting Doppler ankle-arm indexes following conventional PTA was greater (0.26) than that following laser thermal angioplasty (0.12). However, there are many limitations to this trial. The number ofpatients recruited was small (n = 68). Follow-up of these patients was not ideal in that we were unable to perform angiography at 1 year to assess whether improvement of symptoms was due to patency of the treated segment or collateral formation. Similarly we were unable to distinguish recurrence of symptoms due to disease at the PTA site or elsewhere. This was due to inadequate funding and facilities. For the same reasons, duplex ultrasound, which would depict patency or recurrence at the angioplasty site, was not used for follow-up. This study therefore does not assess patency of the treated segment but does assess clinical success at 1 year. In addition, many patients did not return for follow-up assessment. Two patients emigrated, and two other patients moved from Sheffield without leaving a forwarding address. Three patients died during follow-up: one following a traffic accident and two from cerebrovascular accidents. Attempts were not made to interview patients by telephone. Many patients were referred from outlying hospitals and preferred to return there for follow-up. Despite good intentions, compliance was low. In all, 29% of patients in the conventional group and 24% in the laser group were lost to follow-up by 1 year. Despite these criticisms, the two groups of patients are similar both in patient characteristics and follow-up Doppler ankle-arm indexes. Our results do not show any advantage in using laser thermal angioplasty with regard to clinical success. Balloon dilation remains a necessary part of the laser procedure, and this may be a limiting factor in improvement of patency.
In conclusion, the laser probe (Spectraprobe PLR) may increase the primary success rate and be helpful in recanalizing occlusions in which conventional techniques have failed, even if only used as a mechanical tool (11), but it does not confer any advantage in clinical success. This may be due to the fact that balloon dilation remains a necessary part of the procedure to produce a definitive lumen because there is insufficient ablation of obstructing material by the laser. New laser devices are being produced in an attempt to allow more selective ablation of atheroma and produce larger channels by using a diverging beam oflight (3,12,13). Reports oflaser therapy without concomitant balloon dilation are in the preliminary stages. Once they are past the stage of initial evaluation, these should also undergo testing by means of randomized trials, preferably with angiographic follow-up to assess the patency of the treated segment. Acknowledgments: We thank Clare Wales for her invaluable help in organizing follow-up of the patients, and Sally Grant for typing the manuscript. References 1. Sanborn TA, Cumberland DC, Greenfield AJ, Welsh CL, Guben JK. Percutaneous laser thermal angioplasty: initial results and I-year follow-up in 129 femoropopliteallesions. Radiology 1988; 168:121-125. 2. Michaels JA, Goss FW, Shaw P, et al. Laser angioplasty with a pulsed Nd: YAG laser: early clinical experience. Br J Surg 1989; 76:921-924. 3. Murray A, Mitchell DC, Grasty M, Wood RFM, Edwards DH, Basu R. Peripheral laser angioplasty with pulsed dye laser and ball-tipped optical fibres. Lancet 1989; 1471-1474. 4. Lammer J, Pilger E, Karnel F, et al. Laser angioplasty: results of a prospective multicenter study at 3-year follow-up. Radiology 1991; 178:335337. 5. Jeans WD, Murphy P, Hughes AO, Horrocks M, Baird RN. Randomised trial of laser-assisted passage through occluded femoro-popliteal arteries. Br J Radioll990; 63:19-21.
488 • Journal of Vascular and Interventional Radiology November 1991
6.
Spies JB, LeQuire MR, Brantley SD, Williams JE, Beckett WC, Mills JL. Comparison of balloon angioplasty and laser thermal angioplasty in the treatment of femoropopliteal atherosclerotic disease: initial results of a prospective randomized trial-work in progress. JVIR 1990; 1:39-42. 7. Lammer J. Recanalization of arteriosclerotic occlusions with exeimer laser, Nd-YAG laser, or guide wire: preliminary report of a randomized trial (abstr). Radiology 1989; 173(P): 387. 8. Belli AM, Cumberland DC, Procter AE, Welsh CL. Total peripheral
artery occlusions: conventional versus laser thermal recanalization with a hybrid probe in percutaneous angioplasty-results of a randomized trial. Radiology 1991; 181:5760. 9. McLean GK, Burke DR, Marinelli DL. Comment on the clinical appropriateness of an emerging technology (editorial). Radiology 1989; 172:941-942. 10. Anderson JB, Wolinski AP, Wells IP, Wilkins DC, Bliss BP. The impact of percutaneous transluminal angioplasty on the management of peripheral vascular disease. Br J Surg 1986; 73:17-19.
11. Belli AM, Procter AE, Cumberland DC. Peripheral vascular occlusions: mechanical recanalization with a metal laser probe after guide wire dissection. Radiology 1990; 176:539-541. 12. Litvack F, Grundfest WS, Adler L. Percutaneous exeimer-Iaser and exeimer-laser-assisted angioplasty of the lower extremities: results of initial clinical trial. Radiology 1989; 172:331-335. 13. Leon MB, Almagor Y, Bartorelli AL, et al. Fluorescence-guided laserassisted balloon angioplasty in patients with femoropopliteal occlusions. Circulation 1990; 81:143-155.