Excimer laser coronary angioplasty: the New Approaches to Coronary Intervention (NACI) experience

In the New Approaches to Coronary Intervention (NACI) registry, 887 patients were electively treated with excimer laser coronary angioplasty (ELCA) for coronary artery disease. The Advanced Interventional System (AIS) system was used in 487 cases; the Spectranetics system, in 400. The mean age was 63.4 years. Most patients had unstable angina (60.3%); 43.7% had a prior myocardial infarction; and 18.6% were high risk or inoperable patients. Mean ejection fraction was 55.4%. A total of 1,000 lesions were treated in the 887 patients. Of the 1,000 lesions treated with ELCA in the 887 patients, 36% were in the right coronary artery; 33%, left anterior descending; 13%, circumflex; 3%, left main; and 16.6%, vein graft. By angiographic core laboratory analysis available for 752 (85%) patients with 839 lesions, lesions were 12.76 mm long. The minimum lumen diameter increased to 1.29 mm after the laser and finally to 1.95 mm after adjunctive percutaneous transluminal coronary angioplasty (PTCA) (which was performed in 93% of all lesions), with a final residual stenosis of 32.1% and Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow in 95%. Dissections of grades B, C, or D were seen after 22.0% of initial laser attempts, and postlaser perforations were noted in 2.6%. Additional such dissections accumulated after adjunctive PTCA but the perforation rate remained low. Procedural success was achieved in 84% of patients, but 1.2% died, 0.7% experienced Q-wave myocardial infarction (MI), and 2.7% required emergency bypass surgery. Multiple logistic regression analysis could not identify any independent predictors of these in-hospital complications. One-year mortality was 5.7% and the cumulative incidence of Q-wave MI was 1.5%. Coronary artery bypass graft (CABG) surgery was performed in 15.0% of patients whereas 25.5% required repeat percutaneous intervention with a target lesion revascularization rate of 31%. Independent predictors of death, Q-wave MI, or target lesion revascularization (which, combined, occurred in 35.6% of patients) were the absence of prior MI, ELCA in the circumflex, perforation after the procedure, and small (<2 mm) final minimal lumen diameter. Considering the large number of patients with high-risk lesions, laser angioplasty was performed with excellent procedural success rates and a reasonable incidence of major complications.

Light-guiding effect in a two-fluid model of laser angioplasty

Mixing and optical characteristics of blood and optical fluid, utilized in laser angioplasty, are investigated with a two-fluid model. Transport equations are solved for the zone-averaged variables of each fluid with allowance for momentum transport at the interface. The predicted volume fractions of the fluids are used as weight functions to calculate the mixture refractive index. A set of light rays are traced through the fluids to the plaque, utilizing the mixture refractive index. The results indicate significant effect of flow characteristics on the focusing of the rays.

The changing face of coronary interventional practice. The Mayo Clinic experience

BACKGROUND

Devices designed to facilitate or replace conventional percutaneous transluminal coronary angioplasty have been introduced in recent years.

OBJECTIVES

To characterize the changes in percutaneous coronary interventional practice over 16 years and to assess the relative use of these new devices.

METHODS

We performed a retrospective analysis of all patients who underwent percutaneous coronary revascularization at Mayo Clinic, Rochester, Minn, during a 16-year period (1980-1995) and characterized the changes in procedural and clinical factors.

RESULTS

The number of coronary interventional procedures performed increased from 38 in 1980 to 1284 in 1995. Atherectomy and laser angioplasty were incorporated in 1988; their use peaked in 1994 (17% of procedures) but decreased to 9.9% by 1995. In contrast, the use of intracoronary stents has increased steadily since 1990. By 1995, intracoronary stents were placed in 48.2% of procedures. The success rate improved from 55.3% in 1980 to 91.4% in 1995, although patients were older (51 +/- 10 [mean +/- SD] years in 1980 vs 63 +/- 12 years in 1995), had more extensive coronary artery disease (0% with multivessel disease in 1980 vs 47.4% in 1995), had more complex lesions, and often underwent intervention in the peri-infarction setting (2.6% of procedures in 1980 vs 17% in 1995). The rate of referral to emergency coronary bypass surgery after percutaneous procedures declined from 5.2% in 1980 to 0.4% in 1995.

CONCLUSIONS

Current coronary interventional practice is expanding and improving. In contrast to intracoronary stents that have greatly affected current practice, other new devices are used infrequently. Conventional angioplasty, with or without intracoronary stents, remains the dominant treatment strategy.

[Cardiac interventions in Switzerland]

For the year 1995, as for the previous 10 years, a survey of cardiac invasive and surgical procedures in Switzerland was carried out by a standardised questionnaire. At the 25 Swiss centres (10 public non academic, 10 private and 5 academic centres) a total of 11,198 coronary revascularisation procedures were performed, the majority of them (60%) by percutaneous transluminal coronary angioplasty (PTCA). Of all PTCAs, 89% were single vessel interventions. PTCA for ongoing infarction accounted for 6% of all PTCAs. The use of coronary stents has increased to 28% of all angioplasties. Other devices like directional atherectomy and rotablations have lost ground (41 cases). Thirteen interventions with intracoronary laser catheters were recorded. Among the new diagnostic tools, only coronary ultrasound has been used regularly (191 cases). Percutaneous balloon valvuloplasties (64 cases) and catheter closure of congenital shunt defects (32 cases) remained rare interventions. Procedure related mortality for PTCA was 0.7%, infarction occurred in 1.1% and emergency coronary artery bypass grafting (CABG) became necessary in 0.7%. For the first time, the total number of CABGs (4485) decreased. Among the 2077 non-coronary operations, 56% were performed for valve disease and 44% for congenital heart disease. Heart transplantation was performed in 44 patients. The majority of interventional catheter procedures were performed at the 5 university centres whereas the majority of CABGs were carried out at private centres. Four centres performed diagnostic procedures, exclusively. In-house surgical stand-by for PTCA was present in 17 of the 21 interventional centres.

Incorporation of endovascular training into a vascular fellowship program

BACKGROUND

Despite expanding indications for endovascular therapy of peripheral vascular disease, vascular surgeons have largely remained bystanders in the use of this form of treatment for the disease, which is the focus of their profession. Lack of access to training in endovascular techniques is a major obstacle to increasing involvement by vascular surgeons. This paper reports our experience in the endovascular training of vascular surgical fellows without the involvement of radiologists.

METHODS

The results of vascular surgery fellows receiving instruction in endovascular diagnostic and therapeutic procedures from vascular surgery faculty were reviewed.

RESULTS

Endovascular training of vascular surgery fellows exceeded the case levels recommended by all involved societies. A diverse case mix of 355 endovascular diagnostic procedures were performed with a major complication rate of 0.3% and no procedure-related deaths. Two hundred six endovascular interventions were performed, with an initial technical success rate of 96.6%, a 30-day success rate of 93%, no major complications, and an overall intervention-related mortality rate of less than 1%.

CONCLUSIONS

Vascular surgery fellows can receive endovascular training by vascular surgery faculty without the involvement of radiologists and can do so with acceptable success and complication rates. This experience is sufficient to qualify them to perform and teach endovascular therapy in their future practices.

Chronic total obstruction and short-term outcome: the Excimer Laser Coronary Angioplasty Registry experience

Percutaneous transluminal coronary angioplasty for chronic total obstructions is associated with significantly decreased success rates in comparison with those for dilation of subtotal stenoses. Failure usually results from inability to cross the occlusive lesion with a guidewire, although it may result from inability to pass the balloon catheter after the guidewire has been passed. In the Excimer Laser Coronary Angioplasty Registry, 172 chronic total obstructions were treated in 162 patients (10.3% of the 1,569 patients entered). For chronic total obstructions, passage of a guidewire is a prerequisite for laser angioplasty. Once a guidewire crossed an occlusion, the overall laser success rate for treatment of chronic total obstructions was 83%; the extent of stenosis decreased from 100% to 55 +/- 26%. Success was independent of length of the occlusive lesion. In 74% of patients, adjunctive percutaneous transluminal coronary angioplasty was used after laser angioplasty. A final procedural success, defined as residual stenosis of less than 50% and no major complication (coronary artery bypass grafting, myocardial infarction, or death), was achieved in 90%. Major complications were infrequent; 1.2% of patients required coronary artery bypass grafting, and 1.9% had a Q-wave myocardial infarction. Only one death occurred. The use of laser angioplasty may be of particular value when chronic total obstructions can be crossed with a guidewire but not with a conventional balloon catheter or when the occlusion is confirmed to be extremely long.

[Laser versus rotation angioplasty in the recanalization of chronic femoropopliteal arterial occlusions]

Between June 1987 and July 1989 laser angioplasty, and between July 1989 and December 1991 rotation angioplasty was used as the method of choice for the recanalisation of chronic (minimal duration 3 months) arterial occlusions in the femoro-popliteal region. The technical success rate and final results following supplementary balloon dilatation were identical and there was no significant difference between the two groups (laser 87%, rotation 87.7%). For long occlusions (more than 150 mm), the success rate for rotation angioplasty was 60% and significantly higher than for laser angioplasty at 40%. Complication rates for rotation angioplasty were 24.3%, higher than laser angioplasty with 20.3%. This was due to the higher incidence of emboli of 12.1% compared with the laser technique of 7.3%. Cumulative patency rates after two years showed no significant difference (uncorrelated/correlated: laser 53.4%/67.8%; rotation 56.6%/67.5%). Using lytic and aspiration techniques, the higher incidence of embolisation during rotation angioplasty had no adverse effect on final outcome. If both methods are available, it is advisable to treat long occlusions by rotation angioplasty because of the high immediate success rate, whereas short occlusions are best dealt by laser angioplasty because of the lower incidence of embolisation.

Limb perfusion. An objective measure of hemodynamic improvement after angioplasty

Forty-four patients undergoing femoropopliteal angioplasty were studied by magnetic resonance blood flowmetry to determine quantitative limb perfusion. Baseline limb perfusion averaged 0.52 +/- 0.15 mL/min per 100 cc of tissue. Perfusion values for successful angioplasties rose within 72 hours to a mean of 1.40 +/- 0.31 mL/min per 100 cc of tissue. There were five early failures (less than 30 days), in which perfusion fell to 0.54 +/- 0.10 mL/min per 100 cc of tissue; at 6 months, 12 additional angioplasties had failed, with limb perfusion values of 0.68 +/- 0.16 mL/min per 100 cc of tissue. At 6 months, perfusion in four additional limbs had decreased to between 0.7 and 1.0 mL/min per 100 cc of tissue, with a mean change of 0.59 mL/min per 100 cc of tissue; duplex ultrasound imaging at these sites showed restenoses ranging from 50% to 75%. We conclude that lower-leg limb perfusion appears to be a reliable measure of hemodynamic improvement after femoropopliteal angioplasty and may provide an early indicator of impending failure.

Characteristics of shock waves induced by pulsed lasers and their effects on arterial tissue: comparison of excimer, pulse dye, and holmium YAG lasers

Shock waves were investigated using an excimer laser at 308 nm with 18.9 mjoules/pulse, a pulsed dye laser at 480 nm with 100 mjoules/pulse, and a holmium YAG (yttrium-aluminum-garnet) laser at 2.1 microns with 420 mjoules/pulse. At a distance from the target tissue, excimer lasing resulted in no shock waves in saline, while the other lasers produced smaller shock waves than those recorded when the laser was in contact with tissue (0.22 versus 2.0 mm Hg with the pulsed dye laser, 0 versus 0.23 mm Hg with the excimer laser, and 0.44 versus 6.9 mm Hg with the holmium YAG laser; p less than 0.001, respectively). In blood, excimer laser irradiation at a distance from the tissue produced shock waves as great as those produced when the laser was in contact with the tissue (0.19 versus 0.24 mm Hg with the excimer laser, 1.8 versus 3.0 mm Hg with the pulsed dye laser, and 3.1 versus 5.9 mm Hg with the holmium YAG laser; p less than 0.001 with the pulsed dye and holmium YAG lasers, respectively). When lasing was done at 60 mjoules/mm2, the pulsed dye and excimer lasers produced similar shock waves when the lasers were in contact with tissue; however, the holmium YAG laser did not produce shock waves. Thus pulsed lasers can produce shock waves of different characteristics according to the laser source.

Comparison of ablation efficacy of excimer, pulsed-dye, and holmium-YAG lasers relevant to shock waves

Ablation efficacy of pulsed lasers on human arterial tissue and associated shock waves have been investigated by means of excimer laser at 308 nm, pulsed-dye laser at 480 nm, and holmium-YAG laser at 2.1 microns. A multifiber catheter was used for lasing at 420 mjoules/pulse with holmium-YAG, 18.9 mjoules/pulse with excimer, and 100 mjoules/pulse with pulsed-dye laser. Ablation efficiency (ablated volume/energy) was greatest with pulsed-dye laser in blood and excimer laser in saline solution. There was selectivity for atheroma with pulsed-dye laser (ablation efficiency in atheroma versus normal tissue, 58 versus 27 x 10(-2) mm3/joule in blood; p less than 0.005) and holmium-YAG laser (12.6 versus 5.6 x 10(-2) mm3/joule in blood; p less than 0.001). Ablation efficiency of pulsed-dye laser was enhanced by blood (0.58 in blood versus 0.17 mm3/joules in saline for atheroma; p less than 0.005). Shock waves were correlated with ablation efficiency (r = 0.63 and 0.74 for pulsed-dye laser and holmium-YAG laser, respectively). There was neither selectivity for atheroma nor influence of blood medium with excimer laser. Only holmium-YAG laser could ablate tissue at a distance from the target in the blood medium. Histologic findings showed that all lasers could create smooth-edged craters with minimal coagulation necrosis. In conclusion, laser irradiation with holmium-YAG and pulsed-dye lasers could selectively ablate atheromatous tissue with minimal thermal injury, whereas excimer laser could not. Ablation efficiency was correlated with shock waves. Efficiency of pulsed-dye laser was enhanced by blood.

Experience with laser-assisted balloon angioplasty and a rotary angioplasty instrument: lessons learned

Favorable early results with mechanical angioplasty devices and laser-assisted balloon angioplasty have resulted in aggressive marketing and a rapid increase in the use of these devices for the treatment of femoropopliteal occlusive disease. Recent reports, however, have questioned the durability of these less invasive procedures. Since 1986 we have been involved in the clinical investigation of the Kensey dynamic angioplasty instrument and laser-assisted balloon angioplasty. One hundred two balloon angioplasty procedures assisted by the Nd:YAG laser (n = 56) and the Kensey dynamic angioplasty instrument (n = 46) were performed for the treatment of femoropopliteal occlusive lesions. Both Kensey dynamic angioplasty instrument and laser-assisted balloon angioplasty groups were similar with regard to age, operative indication, preoperative ankle-brachial index, lesion length, and distal runoff. Mean follow-up was 19 months in the Kensey dynamic angioplasty instrument group and 15 months in the laser-assisted balloon angioplasty group. Technically successful recanalization was achieved in 67% of Kensey dynamic angioplasty instrument-assisted balloon angioplasty procedures and 82% of laser-assisted balloon angioplasty procedures. Early hemodynamic and clinical improvement was obtained in 59% of Kensey dynamic angioplasty instrument-assisted balloon angioplasty procedures and 57% of laser-assisted balloon angioplasty procedures. Two-year clinical success by life-table analysis was 37% in the Kensey dynamic angioplasty instrument group and 19% in the laser-assisted balloon angioplasty group. The level of subsequent surgical revascularization was not altered in any patient by Kensey dynamic angioplasty instrument-assisted balloon angioplasty or laser-assisted balloon angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal laser-assisted balloon angioplasty of the superficial femoral artery: a multicenter review of 602 cases

A multicenter review of 602 procedures was performed to evaluate the effects of thermal laser-assisted balloon angioplasty on the superficial femoral artery. Four hundred thirty-nine (73%) patients underwent laser-assisted balloon angioplasty for claudication, and 163 (27%) underwent the procedure for limb salvage. Two hundred ninety-two laser-assisted balloon angioplasty procedures were performed for multifocal stenotic disease (greater than 80%) diameter reduction), 258 for total occlusion, and 52 procedures for both superficial femoral artery stenosis and occlusion. The initial recanalization rate was 89% (538/602) depending on the length of the lesion. Success of laser-assisted balloon angioplasty was verified by angioscopy or arteriography, and all patients underwent segmental Doppler studies before discharge and during midterm follow-up extending to 30 months (mean, 11.3 months). Complications occurred in 62 (10%) patients, but only one limb amputation occurred because of a complication related to a laser-assisted balloon angioplasty. Overall, 60% of initially successful procedures have remained patent, but long segment (greater than 7 cm) occlusions have fared poorly (25% patency at 30 months). This minimally invasive technology affords the opportunity to treat short segment (less than 7 cm) symptomatic superficial femoral artery occlusive disease with minimal risk. Initial success and midterm patency rates for appropriate lesions appear to make laser-assisted balloon angioplasty a viable adjunct in the treatment of superficial femoral artery occlusive disease.

PTA and laser assisted PTA combined with simultaneous surgical revascularization

In this study we investigated the efficacy of percutaneous transluminal angioplasty (PTA) and laser percutaneous transluminal angioplasty (LPTA) as an adjunct to surgery in patients with peripheral vascular disease. We report 84 cases of the simultaneous association of direct arterial surgery and angioradiological procedures to treat 82 patients with arterial occlusive disease of the lower limbs. Sixty-five patients (79.2%) were affected by severe claudication and 14 (19.6%) presented with rest pain or gangrene. One patient (1.2%) had signs of acute ischemia. PTA or LPTA were utilized as an inflow procedure in 41 cases (48.8%), as an outflow procedure in 24 (28.6%) and in 19 cases (22.6%) to recanalize an arterial occlusion in the contralateral limb opposite to surgical interventions. Immediate postoperative patency was achieved in 79 cases (94.0%), while in 5 cases (6.0%) it was impossible to perform a satisfactory balloon dilatation. The complication rate was 16.6%: 10 perioperative thromboses, 1 plaque dissection, 1 peripheral embolus, 1 haemorrhage and 1 femoral nerve lesion. No perioperative mortality occurred in this group of patients. Long term patency, analyzed with the life-table method (mean follow-up: 28 months) was respectively 78.0%, 76.3% and 78.9% at 5 years. These data indicate that the combined revascularization technique should always be recommended in properly selected patients because it is less invasive, the surgical risk and operative time are reduced and associated with early and long term cumulative patency rates comparable to those of extensive surgery.