Effects of beta(-)-emitting (188)Re balloon in stented porcine coronary arteries: an angiographic, intravascular ultrasound, and histomorphometric study

BACKGROUND

Restenosis within stents may be prevented by ionizing radiation from an intravascular source.

METHODS AND RESULTS

A liquid beta(-) radiation ((188)Re) balloon was evaluated in a randomized and blinded porcine coronary model of stent restenosis. Group A pigs (n=17) received 0,16, 22, or 29 Gy at 0.5-mm depth, followed by stenting. Restenosis was quantified by angiography, ultrasound, and histomorphometry at 30 days. Group B (n=7) was stented first and then treated with 0 or 29 Gy with follow-up at 60 days. There was a measurable effect at 16 Gy, which improved with increasing doses. At 29 Gy, the histological stenotic area was reduced by 67% (22% versus 66% in controls, P<0.001). Radiation after stenting was equally effective; the stenotic area was reduced (21% versus 65%, P<0.001). At 16 Gy, the vessel just distal to the stent was significantly smaller than control vessels because of intimal thickening (P=0.003). Radiated vessels had distinctive histology consisting of neointimal fibrin and reduced smooth muscle cells and matrix (P<0.0001).

CONCLUSIONS

(188)Re balloon brachytherapy in porcine coronary arteries results in dose-dependent and injury-independent inhibition of stent restenosis for up to 60 days. Restenosis at the borders of the irradiated zone is a potential limitation and may be related to underdosing. Brachytherapy with the (188)Re balloon appears to be safe and feasible for clinical studies.

Leakage of a liquid 188Re-filled balloon system during intracoronary brachytherapy. A case report

We are reporting the first case of an accidental radioactive 188Re leakage of a liquid-filled balloon system. Different analytical methods estimated that approximately 4 mCi 188Re were released. The radiation burden was reduced considerably by the combined therapy with perchlorate and forced volume diuresis. Estimated exposures to all organs were very low with 1.8 rad. A total body nuclear scintigraphy demonstrated uniform 188Re distribution, without specific organ concentration.

Effect of glycoprotein IIb/IIIa inhibition without thrombolytic therapy on reperfusion in acute myocardial infarction: results of ReoMI pilot study

The efficacy of abciximab and moderate dose heparin in attaining reperfusion in acute MI was tested in a multicenter pilot study. Patients with acute MI of less than 6-hr onset triaged to primary PTCA received intravenous abciximab bolus and infusion and heparin (70 u/kg) in the emergency room. Mean time to angiography from administration of abciximab was 34 +/- 23 min. TIMI flow rates were: grade 0-62%, grade I-20%, grade II-9%, and grade III-9%. Primary PTCA was performed with 100% success rate. Access site bleeding occurred in 10% of patients with no incidence of intracranial bleeding. TIMI II/III flow rates were 50% in a patient subset where angiography was delayed by 45 min. While not an alternative to thrombolytics in AMI, abciximab administration in the emergency room in patients triaged to PTCA may be beneficial in situation where door to needle time is delayed as TIMI II/III flows may be attained in some patients. Cathet. Cardiovasc. Intervent. 48:430-434, 1999.

Effects of a positron-emitting vanadium-48 nitinol stent on experimental restenosis in porcine coronary arteries: an injury-response study

BACKGROUND

The major limitation of coronary stenting is restenosis due to exaggerated neointimal thickening. We evaluated a positron-emitting V48 nitinol stent in a porcine coronary model of restenosis.

METHODS AND RESULTS

Pigs (n = 16) received a control nonradioactive and a V48 stent (1.5 or 10.6 muCi) randomized to the left anterior descending artery (LAD) and right coronary artery (RCA). Histology, morphometric variables, and strut injury scores were evaluated after 32 days. Peristrut fibrinoid deposits were greater in the high-dose group (p < 0.0001). Control stent area stenosis (AS) and mean neointimal thickness (NIT) correlated with injury (r = 0.81 and 0.79, respectively). Higher-dose stents reduced AS by 20% (0.57 +/- 0.13 vs. 0.71 +/- 0.16; p = 0.029) and mean NIT by 35% (0.44 +/- 0.16 vs. 0.71 +/- 0.24mm; p = 0.001) compared with controls. Lower-dose 1.5-muCi stents did not differ from controls. NIT over individual struts was reduced in the high-dose group compared with controls by 0.18 mm for grade 1 injury, 0.31 mm for grade 2, and 0.38 mm for grade 3 (p < 0.02 for all comparisons).

CONCLUSIONS

1.5-muCi V48 nitinol stents did not influence vessel histology or restenotic parameters in pig coronary arteries. In contrast, 10.6-muCi stents created a distinctive histological picture consisting of increased fibrinoid deposits on the neointimal-facing side of the struts without cellular organization. Higher dose radioactive stents significantly reduced AS and mean NIT. The reduction in neointimal thickening was greatest when the depth of strut penetration into the vascular wall was most severe.

Chimeric DNA-RNA hammerhead ribozyme to proliferating cell nuclear antigen reduces stent-induced stenosis in a porcine coronary model

BACKGROUND

Stent-induced coronary restenosis is a major clinical and public health problem. Proliferating cell nuclear antigen (PCNA) is an important regulator of cell division, and blocking of its expression after angioplasty may limit intimal proliferation.

METHODS AND RESULTS

We cloned the porcine PCNA gene and constructed a chimeric hammerhead ribozyme to a segment of the gene with human homology. In vitro studies with both cultured porcine and human vascular smooth muscle cells demonstrated uptake of ribozyme within the nucleus and significant inhibition of cellular proliferation. The ribozyme was then delivered locally into pig coronaries in a stent model. At 30 days, histomorphometric analysis showed neointimal thickness of 0.51+/-0.20 mm in the ribozyme group versus 0.71+/-0.27 and 0.66+/-0.25 mm in stent controls and scrambled ribozyme control, respectively (P=0.002, P=0.03). Quantitative angiographic analysis showed late loss of 1.4+/-0.5 mm for ribozyme versus 1.9+/-0.4 and 2.0+/-0.4 mm for the controls (P=0.05 and P=0. 02).

CONCLUSIONS

Chimeric hammerhead ribozyme to PCNA inhibits smooth muscle cell proliferation in vitro and reduces both histomorphometric and angiographic restenosis in the porcine coronary stent model when delivered locally.

Effects of clopidogrel, aspirin and combined therapy in a porcine ex vivo model of high-shear induced stent thrombosis

AIMS

Use of ticlopidine in coronary stenting is limited by delayed onset of action. We studied the effects of clopidogrel, a rapidly acting analog of ticlopidine alone, and in combination with aspirin, in inhibiting stent thrombosis.

METHODS

Unpolished nitinol stents were deployed in a porcine ex vivo arteriovenous shunt and exposed to flowing arterial blood at a shear rate of approximately 1500. s-1. Stent thrombus, platelet aggregation and bleeding times were measured at baseline and after treatment.

RESULTS

Intravenous clopidogrel produced a rapid (within 30 min) and dose-dependent inhibition of stent thrombosis, with 87% reduction at a dose of 10 mg.kg-1 (P < 0.001). Aspirin alone (10 mg.kg-1) was minimally effective (20% inhibition P > 0.05) in inhibiting stent thrombosis. Combined treatment with clopidogrel and aspirin produced 95-98% inhibition of stent thrombosis, even at low doses of clopidogrel (2.5-5.0 mg.kg-1) (P < 0.0001). At effective doses both clopidogrel and combined therapy produced significant prolongation of bleeding time (P < 0.05) and inhibition of platelet aggregation (P < 0.05).

CONCLUSION

Clopidogrel, either alone or combined with aspirin, may have a potential role in preventing stent thrombosis in high-risk clinical situations.

Biocompatibility of polyurethane-coated stents: tissue and vascular aspects

To assess the arterial injury triggered by polyurethane-coated vs. uncoated stents, six polyurethane-coated and six bare nitinol stents were implanted in rabbit carotid arteries. All animals were sacrificed 4 wk after stent placement. Sections were evaluated by histology and morphometric analysis. At 4 wk, both the coated and uncoated stent struts were entirely endothelialized. The spaces between the struts showed a relatively mild proliferative response, with a few sections demonstrating neovascularization around the struts. Polyurethane coating was associated with an inflammatory tissue response consisting of lymphocytic infiltration and foreign-body reaction, with the appearance of multinucleated giant cells. Lumen, intimal, and medial cross-sectional areas varied little between coated and uncoated stented vessels (2.45+/-0.19 vs. 2.47+/-0.47 mm2, 1.17+/-0.52 vs. 0.78+/-0.30 mm2, and 0.66+/-0.18 vs. 0.58+/-0.27 mm2, respectively). In the rabbit carotid artery model, polyurethane coating does not affect the degree of neointimal proliferation after endovascular stenting compared with the conventional stenting approach. However, the inflammatory tissue response may indicate a low intrinsic biocompatibility of this stable polymer, so that it may not be an ideal material for coating intravascular devices.

Laser wire for crossing chronic total occlusions: "learning phase" results from the U.S. TOTAL trial. Total Occlusion Trial With Angioplasty by Using a Laser Wire

The Prima laser guidewire system (Spectranectics Corp., Colorado Springs, CO) consists of an 0.018" hypotube containing a bundle of 45-microm optical fibers coupled to a pulsed excimer laser operating at a tip fluence of 60 ml/mm2 and a repetition rate ranging from 25-40 Hz. This laser guidewire was specifically designed to cross total occlusions refractory to passage with conventional wires. The Prima wire was evaluated in a feasibility study at 15 U.S. centers. Following failure to cross a total occlusion with approved guidewires, the Prima wire was utilized in 179 patients. Average age of subjects was 61 yr. Lesion locations included left anterior descending (36%), right (45%), and circumflex (19%) coronary arteries. Mean angiographic age of total occlusions was 70 wk (range, 2-1,020 wk, median, 14 wk). The use of the Prima wire either solely or in combination with conventional guidewires resulted in successful crossing in 61% of these previously impenetrable occlusions. Failure of the device was commonly related to length of the occlusion and tortuosity along the occluded pathway. Major complications included myocardial infarction in 7 patients (3.9%), tamponade in 3 (1.7%), and death in 2 (1.1%). This "learning phase" pilot study confirmed the feasibility of a laser guidewire in chronic total occlusions that are resistant to passage of conventional guidewires. An extended registry at these investigative sites is planned.

Characterization of a positron emitting V48 nitinol stent for intracoronary brachytherapy

Percutaneous transluminal coronary angioplasty (PTCA) is currently one of the most common treatments for obstructive coronary artery disease. The long term success of the treatment, however, is severely limited by restenosis. Recently, different investigators have begun to study the possibility of radiation therapy in restenosis prevention and have shown promising results. However, an optimal radiation delivery device for delivering a highly localized radiation dose to the arterial medial layer while preserving the viability of the artery has yet to be established. In this article, we discuss the development of a unique mixed gamma/beta brachytherapy source capable of delivering high radiation dose to a 0.5 mm thick vessel wall by proton-beam activating an existing nickel titanium stent to produce vanadium-48. The dose distribution of the activated stent is determined by computer simulation using MCNP Monte Carlo code and is verified by radiochromic film measurement.

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.

Influence of gender on in-hospital clinical and angiographic outcomes and on one-year follow-up in the New Approaches to Coronary Intervention (NACI) registry

Higher complication rates and lower success rates for treatment of women compared with men have been reported in prior studies of coronary angioplasty and in most early reports of outcome with new coronary interventional devices. In multivariate analysis this has been attributed largely to older age and other unfavorable clinical characteristics. These results are reflected in the current guidelines for coronary angioplasty. Women in prior studies have also had different distributions of vessel and lesion characteristics, but the influence of these differences on the outcome of new-device interventions have not been adequately evaluated. This article evaluates the influence of gender on clinical and angiographic characteristics, interventional procedure and complications, angiographic success, and clinical outcomes at hospital discharge and 1-year follow-up, as observed in the New Approaches to Coronary Intervention (NACI) registry. The NACI registry methodology has been reported in detail elsewhere in this supplement. This study focuses on the 90% of patients-975 women and 1,880 men-who had planned procedures with a single new device and also had angiographic core laboratory readings. Women compared with men were older, had more recent onset of coronary ischemic pain that was more severe and unstable, and had more frequent histories of other adverse clinical conditions. The distributions of several but not all angiographic characteristics before intervention were considered more favorable to angioplasty outcome in women. Differences were observed in device use and procedure staging. Angiographically determined average gain in lumen diameter after new-device intervention, with or without balloon angioplasty, was significantly less in women (1.38 mm) than in men (1.53 mm; p < 0.001); this 0.15 mm difference is consistent with the 0.16-mm smaller reference vessel lumen diameter of women. However, final percent diameter stenoses and TIMI flow and lesion compliance characteristics were similar. Among procedural complications, only treatment for hypotension, blood transfusion, and vascular repair occurred more often in women. More women than men were clinically unstable (2.1% vs 1.1%) or went directly to emergent coronary artery bypass graft surgery (CABG; 1.2% vs 0.6%) on leaving the interventional laboratory. However, in-hospital death (1.4% vs 1.1%), Q-wave myocardial infarction (MI) (0.9% vs 1.1%), and emergent CABG (1.5% vs 1.0%, for women and men, respectively) were not significantly different. Nonemergent CABG was more frequent in women (1.8% vs 0.9%; p < 0.05) and length of hospital stay after device intervention was longer (4.4 days vs 3.8 days in men; p < 0.01). In both univariate and multivariate analyses gender did not emerge as a significant variable in relation to the combined endpoint, death, Q-wave MI, or emergent CABG at hospital discharge. At 1-year follow-up more women than men reported improvement in angina (70% vs 62%) and fewer women than men had had repeat revascularization (32% vs 36%). Similar proportions were alive and free of angina, Q-wave MI and repeat revascularization (46% of women vs 45% of men). Although several procedure-related complications were more frequent in women than men after coronary interventions with new devices, no important disadvantages were observed for women in the rates of major clinical events at hospital discharge and at 1-year clinical follow-up. Additional studies are needed to evaluate the complex interplay of clinical, vessel, and lesion characteristics on success and complications of specific interventional techniques and to determine whether gender, per se, is a risk factor and whether gender specific interventional strategies may be beneficial.

Long-term follow-up of a high risk cohort after stent implantation in saphenous vein grafts

OBJECTIVES

We sought to provide short- and long-term clinical outcomes of a high risk cohort treated with stents in saphenous vein grafts (SVGs).

BACKGROUND

Data on the long-term outcome of SVG stenting in high risk patients are limited.

METHODS

Johnson & Johnson stents were implanted in the SVGs of 186 patients (302 stents, 244 lesions). Ninety percent of patients presented with myocardial infarction (MI) or unstable angina (mean +/- SD ejection fraction [EF] 44 +/- 11%, patient age 71 +/- 9 years, graft age 9.4 +/- 5 years). Using a risk score classification, 155 patients (83%) were defined as high risk for repeat surgical repair or angioplasty.

RESULTS

The procedural success rate was 97.3%, with 2.7% major complications (death, Q wave MI, coronary artery bypass graft surgery [CABG]). Clinical follow-up was obtained in 177 patients (mean 19.1 +/- 13.5 months, range 7 to 59). Event rates were 10% for death; 9% for MI; 11% for repeat CABG; and 15% for repeat angioplasty (total events 45%). Kaplan-Meier estimated survival and event-free survival at 4 years were 0.79 +/- 0.06 and 0.29 +/- 0.07, respectively. Predictors of death were congestive heart failure (p < 0.01) and EF <44% (p < 0.05). Predictors of combined events of death, MI and CABG were low EF (p < 0.01) and high SVG age (>10 years, p < 0.01). There were 66 revascularization procedures (35% of patients), 24% of which were in nontarget lesions. Fifty-three percent of the cardiac events occurred during the first year of follow-up. Of the 160 survivors, 36% were free of angina, 49% were in Canadian Cardiovascular Society functional class I or II, and 15% were in class III or IV. Sixty-nine percent of patients were in class I or II according to the Specific Activity Scale, and 31% of patients were in class III or IV.

CONCLUSIONS

Balloon-expandable stent implantation in the SVGs of high risk patients is associated with a low early complication rate. Expected survival rates are good, as are the anginal and functional classifications, but there is a high rate of recurrent events and need for repeat revascularization. Vein graft stenting is an acceptable palliative option in many high risk patients.

Sustained local drug delivery to the arterial wall via biodegradable microspheres

This study was designed to evaluate the feasibility of applying locally delivered polylactic acid microspheres for drug delivery to the arterial wall. To study drug persistence, rhodamine-loaded microspheres were infused into one carotid artery of 14 rabbits and plain rhodamine solution into the other by using a porous balloon. To study tissue response, plain microspheres and dexamethasone-loaded microspheres were infused into the carotid arteries of another group of rabbits. To study the antiproliferative effects of locally delivered drug, 20 rabbits were subjected to overstretch balloon injury to both carotid arteries and divided into 4 groups: injury alone, plain microspheres, dexamethasone-loaded microspheres, and microspheres containing colchicine and dexamethasone. Fluorescent microspheres persisted in the vessel wall for 4 wk, whereas rhodamine without microspheres disappeared at 72 h. Histopathologic studies in arteries infused with unloaded microspheres showed inflammatory cell infiltrate with polymorphonuclear cells at 1 wk and macrophages and giant cells at 4 wk. Arteries infused with dexamethasone-loaded microspheres did not show any inflammatory cell infiltrate. Local delivery of dexamethasone or dexamethasone plus colchicine did not result in significant change in the intima-to-media ratio or in residual lumen following balloon injury. Polylactic acid microspheres may be used for prolonged delivery of drugs or other bioactive agents locally to the arterial wall. They induce an inflammatory reaction that is suppressable by dexamethasone in the microspheres. Dexamethasone or dexamethasone and colchicine delivered via this system, however, failed to reduce the degree of intimal hyperplasia after overstretch balloon injury to the rabbit carotid arteries.

Temporary arterial stenting: comparison to permanent stenting and conventional balloon injury in a rabbit carotid artery model

The objective was to assess the arterial wall response to temporary stenting with a removable nitinol stent in comparison with permanent stenting and balloon injury at 28 days in the rabbit carotid artery. Restenosis remains an important limiting factor after the implantation of permanent metallic stents and balloon angioplasty. We have developed a temporary nitinol stent that uses a bolus injection of warmed saline to collapse the stent for percutaneous removal. Vascular changes related to the thermal saline bolus injection required to remove a nitinol implanted stent were assessed in 12 rabbit carotid arteries at 7 and 28 days postinjection. Nitinol stents, inflated to 3.0 mm diameter, were implanted for 3 days (n = 6) and histology and quantitative histomorphometry examined at 28 days. Results were compared with permanently implanted stents (n = 5) and balloon injury (n = 9). Dual bolus injection of 10 ml at 70 degrees C created an acute necrotizing injury and chronic neointimal proliferation, whereas injections of 5 ml at 63 degrees C were minimally injurious. Temporary stenting resulted in the least neointimal proliferation measured by the intima to media ratio (0.22 +/- 0.10 vs. 1.59 +/- 0.31 for permanent stenting and; 0.49 +/- 0.14 for balloon injury; P < 0.001). Temporary stenting maintained a significantly larger lumen than balloon (1.53 +/- 0.72 mm2 vs. 0.64 +/- 0.14 mm2; P < 0.001), which could not be explained by absolute changes in intimal cross sectional area (0.14 +/- 0.07 mm2 vs. 0.21 +/- 0.06 mm2 respectively; P = 0.33). Temporary stenting resulted in a relatively larger vessel area within the external elastic lamina than with balloon (2.28 +/- 1.06 mm2 vs. 1.30 +/- 0.18 mm2; P = 0.007). The thermal stent recovery process can create necrotizing vascular injury and neointimal proliferation at higher temperatures and injectate volumes. Stent removal after 3 days using 63 degrees C saline bolus injection results in less neointimal proliferation than with permanent stents or balloon injury. In comparison to balloon injury, temporary stenting also may have a long-lasting beneficial effect on vessel recoil and remodeling, resulting in larger lumen size after stent removal.

Effects of GP IIb/IIIa receptor monoclonal antibody (7E3), heparin, and aspirin in an ex vivo canine arteriovenous shunt model of stent thrombosis

BACKGROUND

Thrombosis is an important limitation of metallic coronary stents, especially in smaller vessels in which shear rates are high. Monoclonal antibody to platelet glycoprotein IIb/IIIa receptor (7E3) has been shown to inhibit shear-induced platelet aggregation. In this study, we compared the effects of 7E3, heparin, and aspirin on stent thrombosis in an ex vivo arteriovenous shunt model of high-shear blood flow.

METHODS AND RESULTS

An ex vivo arteriovenous shunt was created in 10 anesthetized dogs. Control rough-surface slotted-tube nitinol stents (n = 72) expanded to 2 mm in diameter in a tubular perfusion chamber were interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100s-1 for 20 minutes. The animals were treated with intravenous murine 7E3 (Fab')2 (0.2, 0.4, and 0.8 mg/kg), heparin (100 U/kg), or aspirin (10 mg/kg). Effects of the test agents on thrombus weight, platelet aggregation, platelet P-selectin expression, bleeding time, and activated clotting time (ACT) were quantified. 7E3 reduced stent thrombosis by 95% (20 +/- 1 to 1 +/- 1 mg, P < .001) and platelet aggregation by 94% (14 +/- 2 to 1 +/- 1 omega, P < .001) at the highest dose (0.8 mg/kg). 7E3 significantly prolonged bleeding time but had no effect on ACT and platelet P-selectin expression. Heparin prolonged ACT but had no significant effect on stent thrombosis or platelet aggregation. Aspirin, although it inhibited platelet aggregation by 65%, had no effect on stent thrombosis (19 +/- 2 versus 20 +/- 1 mg in controls).

CONCLUSIONS

7E3 produced a dose-dependent inhibition of acute stent thrombosis under high-shear flow conditions. Stent thrombosis was resistant to heparin and aspirin. Thus, 7E3 may be an effective agent for preventing stent thrombosis.

Subacute thrombosis and vascular injury resulting from slotted-tube nitinol and stainless steel stents in a rabbit carotid artery model

BACKGROUND

Our objectives were to quantify the thrombogenicity and extent of vascular injury created by slotted-tube geometry stainless steel and nitinol coronary stents in a rabbit carotid artery model.

METHODS AND RESULTS

Stents were implanted in rabbit right carotid arteries without antiplatelet therapy. Stainless steel stents were implanted for 4 days while nitinol stents were placed for 4 and 14 days (n = 8, 8, and 6, respectively). Stent thrombosis was assessed by thrombus weight, grading thrombus encroachment of the lumen, and by blood flow in the stented and contralateral arteries. Stainless steel stents at 4 days contained more thrombus than 4- and 14-day nitinol stents (20.0 +/- 5.9 versus 2.5 +/- 0.6 and 2.7 +/- 0.3 mg, respectively; P < .000001). Stainless steel stents were more often occluded by thrombus (6 of 8) or contained more subocclusive thrombus (2 of 8) than nitinol stents (0 of 14, P < .002). Resting blood flow was reduced in arteries with stainless steel stents compared with 4- and 14-day nitinol stents (1.5 +/- 2.8 versus 24.0 +/- 2.0 and 25.5 +/- 1.9 mL/min, respectively, P < .000001). Stainless steel stents were less uniformly expanded, had deeper strut penetration into the vascular wall, and were associated with more extensive medial smooth muscle cell necrosis. There were strong correlations (r = .77 to .95) between variables of thrombosis extent (thrombus weight and grade) and histologically determined vascular injury (strut penetration and medial necrosis).

CONCLUSIONS

Slotted-tube stainless steel stents were more thrombogenic and created more extensive vascular injury than nitinol stents in a rabbit carotid artery model. The mechanisms underlying these differences probably are related to metallurgic and design geometry properties of the two stent types.

Prevention of Restenosis by Local Drug Delivery

Local drug therapy for preventing restenosis after angioplasty has been investigated for over a decade. Biologically active agents ranging from drugs to genes can be delivered locally using a wide variety of catheters. Microspheres, liposomes, and polymers have been used to enhance drug retention at the delivery site. More recently stents have been investigated as devices to attain local drug delivery, either by coating with polymers, seeding with genetically modified cells or by using them as a source of local radiation. Though the best method of delivering agents locally remains undefined, this approach is likely to emerge as an essential mode of therapy in the near future.

Usefulness of a prototype directional catheter for excimer laser coronary angioplasty in narrowings unfavorable for conventional excimer or balloon angioplasty

We report clinical and angiographic results in 53 patients with 57 significant coronary or saphenous vein graft narrowings treated with directional excimer laser angioplasty. The target vessels were the left main (1%), anterior descending (32%), circumflex (19%), right coronary artery (39%), and vein grafts (9%). Lesions were morphologic class B1 (18%), B2 (79%), or C (3%), with 40 de novo and 17 restenotic lesions. Adjunctive balloon angioplasty was used in 53 lesions (93%). Mean pre- and postprocedural minimal lumen diameters were 0.6 +/- 0.3 and 1.9 +/- 0.7 mm (p < 0.001), corresponding to a mean diameter stenosis of 72 +/- 20% and 27 +/- 16%. Procedural success rate was 91%. Cumulative risk of death, Q-wave myocardial infarction, or emergency bypass operation was 9% (5 patients). Of patients who had a successful laser procedure, 28 (60%) with 30 lesions underwent angiographic follow-up at 6 +/- 3 months after the procedure. Restenosis rates (> 50% diameter restenosis or acute gain loss) were 37% and 23%, respectively. Four patients underwent bypass, 3 angioplasty, and 1 patient died from cancer. This study demonstrates the feasibility of directional application of laser energy to selected unfavorable narrowings for conventional excimer laser or balloon angioplasty. Further evaluation of this device using the now standard saline infusion technique is necessary to establish its ultimate role as a primary interventional device.

Six month outcome and determinants of adverse clinical events after successful excimer laser coronary angioplasty. ELCA A.I.S. Multicenter Registry

OBJECTIVE

To describe the six month outcome and predictors of adverse clinical events following successful excimer laser coronary angioplasty (ELCA).

DESIGN

Retrospective analysis of comprehensive data collected at time of initial procedure and during planned follow-up intervals.

SETTING

There were 35 participating institutions throughout the United States.

PATIENTS

The study population was comprised of 3,069 patients who had successful ELCA and completed follow-up at 6 months, representing 91% of eligible cases. Forty percent had prior balloon angioplasty and 34% had prior bypass surgery.

MEASUREMENTS

Patient symptomatology was assessed by Canadian Cardiovascular Society functional (CCSF) class. Interim adverse clinical events [death, Q wave myocardial infarction (QMI), repeat intervention, bypass surgery, and a composite end-point] were tracked. Twenty-six pre-ELCA clinical, angiographic and procedural variables were evaluated to assess their ability to predict outcome.

RESULTS

At 6 months, there was 2.8% mortality, 2.5% incidence of QMI, and 28.7% required either repeat intervention or bypass surgery. Overall, 69.2% of patients had no adverse event. In this cohort, the pre-ELCA CCSF class grade was 2.7 +/- 1.2, but at 6 months, it was 0.7 +/- 1.1 (p < 0.001). The multivariate predictors of the composite end point were gender, stenosis location, and rest and unstable angina.

CONCLUSIONS

There is an excellent 6 month outcome after successful ELCA in this selected population with complex coronary artery disease. The majority of patients without interim events enjoy significant alleviation of symptoms. The predictors of adverse events are clinical rather than angiographic.

Influence of expanded balloon diameter on Palmaz-Schatz stent recoil

After successful stent implantation, the residual luminal diameter of the stented vessel is usually smaller than the maximal stent-expanded balloon diameter. The goal of this study was to determine whether immediate vessel diameter recoil after Palmaz-Schatz stenting is affected by the final expanding balloon diameter used during stent deployment. Single Palmaz-Schatz balloon expandable stents were successfully placed in 108 stenotic lesions. There were 68 patients with 75 saphenous vein graft (SVG) and 30 patients with 33 native coronary artery lesions, including 26 restenotic and 82 de novo occlusive (> 50% diameter stenosis) lesions. Quantitative coronary angiography was used for the assessment of stent recoil, defined as the difference between the minimal diameter of the fully expanded balloon and the postprocedure minimal lumen diameter divided by minimal diameter of the fully expanded balloon. A strong correlation (r = 0.94) was found between the minimal diameter of the fully expanded balloon and poststenting minimal lumen diameter. Immediate recoil was 11.3 +/- 7.5%, responsible on an average for 0.4 +/- 0.2-mm acute lumen loss. Recoil was less in SVG than in coronary arteries (9.7 +/- 6.6% vs. 14.0 +/- 7.8%; P = 0.004, and 0.3 +/- 0.2 vs. 0.4 +/- 0.2 mm; p = 0.01). Lesions were divided into four subgroups, based on the final stent expanding balloon diameter: (1) < or = 3.0 mm (n = 33); (2) > 3 < or = 3.5 mm (n = 43); (3) > 3.5 < or = 4 mm (n = 23); and (4) > 4 mm (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of restenosis after excimer laser coronary angioplasty

One hundred twenty-five lesions successfully treated with excimer laser coronary angioplasty at 3 centers were analyzed in a central core laboratory using detailed quantitative angiographic analysis. Sixty-seven narrowings had restenosis (> or = 50% diameter stenosis at restudy). Correlates of restenosis were as follows: baseline diameter stenosis was 79% in the restenosis group versus 71% in the group without restenosis (p = 0.0002), baseline minimal diameter stenosis was 0.55 mm in the restenosis group versus 0.72 mm in the group without restenosis (p = 0.006), final diameter stenosis was 40% in the restenosis group versus 32% in the group without restenosis (p = 0.002), lesion length > or = 7 mm was present in 43% of the restenosis group versus 21% in the group without restenosis (p = 0.009), and Thrombolysis in Myocardial Infarction trial flow 0 to 2 was 33% in the restenosis group versus 15% in the group without restenosis (p = 0.025). The strongest multivariate correlate of restenosis was the baseline diameter stenosis (p = 0.003). Whereas most predictors were not controllable, achieving a low residual diameter stenosis that is operator-dependent can favorably influence the restenosis rate.

Stent implantation of saphenous vein graft aorto-ostial lesions in patients with unstable ischemic syndromes: immediate angiographic results and long-term clinical outcome

OBJECTIVES

This study examined the immediate angiographic and long-term clinical results of stenting saphenous vein graft aorto-ostial stenosis at a single center.

BACKGROUND

Data on the feasibility, safety and short- and long-term clinical results of stent implantation in aorto-ostial lesions in patients with unstable angina are limited.

METHODS

Palmaz or Palmaz-Schatz stents were deployed in 29 patients (mean [+/- SD] age 70 +/- 10 years) with complex (B2 or C) vein graft aorto-ostial lesion morphology. All patients had angina at rest; 23 (79%) had a previous myocardial infarction; and 13 (45%) had two previous bypass operations (mean graft age 9 +/- 5 years). Mean left ventricular ejection fraction was 42 +/- 13%.

RESULTS

Thirty-two stents were deployed in 25 new and 4 restenotic aorto-ostial lesions. Ten additional stents were implanted in five patients for eight lesions other than at ostial locations. Stent implantation was successful in all patients. There was no death, Q wave myocardial infarction, bypass surgery or stent thrombosis in the first 30 days. Stenting improved minimal lumen diameter from 0.7 +/- 0.5 mm (95% confidence interval [CI] 0.5 to 0.8) to 3.3 +/- 0.5 mm (CI 3.2 to 3.5) and percent diameter stenosis from 80 +/- 13% (CI 75% to 85%) to 1 +/- 12% (CI -3% to 6%) (p < 0.001 for both variables). Immediate loss from recoil was 0.2 +/- 0.2 mm (CI 0.2 to 0.3), corresponding to a percent recoil of 7 +/- 5% (CI 5% to 9%). Clinical follow-up in all patients at a mean of 11 +/- 8 months revealed that 27 patients (94%) were free of death or myocardial infarction. Bypass surgery and balloon angioplasty were required in one (3%) and two (6%) patients, respectively. In 21 (88%) of the remaining 24 patients, symptoms were lessened by two or more symptom classes.

CONCLUSIONS

Palmaz or Palmaz-Schatz stent implantation for saphenous vein graft aorto-ostial stenosis has a high likelihood of immediate success and is associated with a large immediate gain in lumen diameter. Thirty-day and long-term adverse event rates are low. These data suggest that stenting saphenous vein graft aorto-ostial lesions is an acceptable therapeutic option in selected elderly patients with unstable angina and large-diameter vessels.

Kinetics of drug delivery to the arterial wall via polyurethane-coated removable nitinol stent: comparative study of two drugs

Polymer-coated removable stents were used to deliver 14C-labeled etretinate and 3H-labeled forskolin to the vessel wall in 31 New Zealand White rabbits to study their kinetics. Stents loaded with etretinate (n = 8) and forskolin (n = 14) were implanted in the rabbit carotid arteries, and the animals were euthanized at different time intervals. Drug levels were measured in the media and adventitia of the stented segment, in distant tissues, and in blood. In four rabbits, forskolin-loaded stents were percutaneously retrieved 2 hr after implantation in the carotid artery, and the tissue and blood levels were determined 2 and 24 hr after retrieval. In seven rabbits etretinate-loaded stents were retrieved 72 hr after implantation in abdominal aorta, and drug levels were measured in the tissues and blood immediately after and at 1 and 4 days after retrieval. Levels of etretinate in the vessel wall peaked at 24 hr (250 ng/mg) and remained high up to 72 hr (185 ng/mg) after stent placement. Levels of forskolin peaked within 2 hr of stent placement (135 ng/mg) and rapidly declined to 4.9 ng/mg at 24 hr with the stent in situ. About 50% (1.4 mg) of the original etretinate remained in the stent at 72 hr compared to about 5% (0.08 mg) of forskolin at 24 hr. Ratio of peak drug levels in the vessel wall to those in the blood was 6,000 for etretinate and 780 for forskolin. (ABSTRACT TRUNCATED AT 250 WORDS)

Localized arterial wall drug delivery from a polymer-coated removable metallic stent. Kinetics, distribution, and bioactivity of forskolin

BACKGROUND

Coronary stenting is associated with two major complications: subacute thrombosis and neointimal proliferation resulting in restenosis. Our hypothesis is that the biocompatibility of metallic stents can be improved by coating with a polymer membrane that delivers agents that favorably modify the local arterial microenvironment. This study evaluates the kinetics, distribution, and bioactivity of the model drug forskolin delivered to the local arterial wall by a polyurethane-coated removable metallic stent.

METHODS AND RESULTS

Stents were used in rabbit carotid arteries (n = 20) for as long as 24 hours. The quantity of forskolin bound to the stent decreased exponentially with a half-life of 5.8 hours. Blood concentrations peaked at 140 +/- 39 pg/microL at 4 hours. The adjacent arterial media contained 60 +/- 39 ng/mg, which was 380- and 460-fold greater than the contralateral carotid media and the systemic blood, respectively (P < .0001). Media forskolin concentrations declined exponentially over time with a tissue half-life of 5.0 hours. Drug distributed throughout the vessel wall with decreasing gradients in the radial and axial dimensions consistent with a diffusion process. Removal of the stent was associated with a 100-fold decline in media forskolin concentration within 2 hours. Forskolin release was associated with a sustained 92% increase in carotid blood flow and a 60% decrease in local arterial resistance compared with coated control stents (P < .005). In another set of rabbits (n = 14) using a carotid crush injury, flow-reduction model, forskolin prolonged the time to flow variation and occlusion by 12-fold compared with the use of bare metal stents and 5-fold compared with the use of polyurethane-coated stents (P < .0001).

CONCLUSIONS

A polymer-coated metallic stent can deliver forskolin to the local arterial wall in high concentrations relative to the blood or other tissues. High local drug concentrations are dependent on maintaining stent-to-tissue gradients. The delivered drug is biologically active, demonstrating vasodilating and antiplatelet properties.

Current status and prospects for the use of temporary stents

Temporary stenting appears to be an attractive potential therapy that combines some of the benefits of permanent stenting without the need for permanent endovascular prostheses and oral anticoagulation. The devices used for temporary stenting are still evolving. The Flow Support Catheter showed promise in the early clinical trial phase but is not being pursued by the original manufacturer because the device was associated with a high rate of thrombosis and suboptimal overall success rate. The experience with the Instent is limited and the removal of its unattached version relies upon catching the end of the stent in the retrieval device (a wire loop); also, its safety and reliability still need to be proved. The HARTS device is currently in the preclinical phase, but available data from animal studies show it to be a feasible device for coronary use. Its potential applications include use as a permanent stent, a temporary stent, a repositionable stent, a primary lesion-dilating device, or a local drug-delivery vehicle. Clinical trials are likely to commence in the foreseeable future for one or more of these applications.

Percutaneous excimer laser coronary angioplasty: results in the first consecutive 3,000 patients. The ELCA Investigators

OBJECTIVES

We report the comprehensive results of the first consecutive 3,000 patients treated in an excimer laser coronary angioplasty registry.

BACKGROUND

Excimer laser coronary angioplasty involves the use of a pulsed, 308-nm ultraviolet laser transmitted by optical fibers to reduce coronary stenoses. Preliminary reports have described safety and efficacy profiles in small numbers of patients.

METHODS

Patients were enrolled in a prospective, nonrandomized manner. The catheters used were 1.3, 1.6, 2.0, 2.2 and 2.4 mm in diameter, at energy densities up to 70 mJ/mm2. Procedures were performed by standard angioplasty technique with conventional guide catheters.

RESULTS

Seventy-five percent of patients were male, 68% were in Canadian Cardiovascular Society functional class III or IV and the cohort included 3,592 lesions. Procedural success (final stenosis < or = 50% without in-hospital Q wave myocardial infarction, coronary artery bypass surgery or death) was 90% and did not differ between the first 2,000 and the last 1,000 patients treated. There was no significant difference in success or complication rates with respect to lesion length, nor were there differences between selected complex and simple lesions. Complications included in-hospital bypass surgery (3.8%), Q wave myocardial infarction (2.1%) and death (0.5%). Coronary artery perforation occurred in 1.2% of patients (1% of lesions) but significantly decreased to 0.4% in the last 1,000 patients (0.3% of lesions). Angiographic dissection occurred in 13% of lesions, transient occlusion in 3.4% and sustained occlusion in 3.1%. Comprehensive lesion morphologic data collected in the latter portion of the study showed the procedure predominantly limited to American College of Cardiology-American Heart Association type B2 and C lesions, with no significant difference in short-term outcome between groups.

CONCLUSIONS

Excimer laser angioplasty can be safely and effectively applied, even in a variety of complex lesions not well suited for percutaneous transluminal coronary angioplasty. These types may include aorto-ostial, long lesions, total occlusions crossable with a wire, diffuse disease and vein grafts. Most recent data show a trend for the selection of predominantly complex lesions and a reduction in the incidence of perforation. This procedure may broaden the therapeutic window for the interventional treatment of selected complex coronary artery disease.

Coronary perforation after excimer laser coronary angioplasty: the Excimer Laser Coronary Angioplasty Registry experience

OBJECTIVES

This study assessed the frequency of perforation with excimer coronary angioplasty.

BACKGROUND

Coronary artery perforation after conventional percutaneous transluminal coronary angioplasty is extremely rare. Because laser coronary angioplasty involves actual tissue ablation, it has an increased potential for perforation.

METHODS

All patients in the Excimer Laser Coronary Angioplasty Registry were included in this prospective study. Those who had a perforation related to the procedure were compared with those who did not have this complication.

RESULTS

Of 2,759 consecutive patients in the Excimer Laser Coronary Angioplasty Registry, 36 (1.3%) had perforation. In these patients, the left anterior descending coronary artery was the most frequently treated vessel (53%). There were no differences in fiber sizes between patients with and those without perforation. Among the patients with perforation, 36.1% required coronary artery bypass surgery, 16.7% experienced an infarction and 5.6% had a fatal outcome. Among the patients without perforation, the rates were 3.1%, 3.8% and 0.6%, respectively. However, 41.7% of the patients with documented coronary artery perforation did not need coronary artery bypass surgery or experience myocardial infarction or death. No angiographic characteristics distinguished lesions with from those without perforation. The frequency of coronary artery perforation declined over time with increasing operator experience, from 1.6% in the first 1,888 patients to only 0.4% in the last 1,000 patients (p = 0.002).

CONCLUSIONS

With increasing operator experience, the rate of perforation with excimer laser coronary angioplasty has decreased. When perforation occurs, subsequent event rates increase.

Baseline characteristics and therapeutic goals in the New Approaches to Coronary Intervention (NACI) registry

BACKGROUND

The New Approaches to Coronary Intervention (NACI) voluntary registry was designed to study the use, safety, and efficacy of new percutaneous transluminal interventional devices including directional coronary atherectomy, the transluminal extraction catheter, the rotablator, the Palmaz-Schatz stent, the Gianturco-Roubin stent, the Advanced Interventional Systems (AIS) laser, and the spectranetics laser.

METHODS

To date, more than 3800 consecutive patients treated for the first time with a new device at 41 centers have been entered into the registry. Complete detailed information about the patient, lesions, device characteristics, reasons for device selection, and procedural data, such as adjunctive use of conventional balloon angioplasty (PTCA), was available for the first 2835 patients.

RESULTS

The registry shows that 88% of the 3233 attempts with a new device were intended as a definitive treatment of target lesions, frequently in combination with adjunctive PTCA. The remaining 12% of attempts with a new device were unplanned, prompted by unexpected complications, unsuccessful attempts, or suboptimal results with PTCA. Although there was some overlap in the indications for selecting a given interventional device, the variation from device to device was sufficiently large to caution users against any direct comparison of either safety or efficacy between devices without careful attention to the differences in baseline patient and lesion characteristics, treatment plans, and the circumstances of device use.

CONCLUSION

This report provides the first comprehensive overview of how new interventional devices are currently being used in the treatment of coronary artery lesions at the 41 centers participating in the NACI registry.

Treatment of refractory coronary occlusions with a new excimer laser catheter: preliminary clinical observations

BACKGROUND

Total coronary occlusion is a frequent cause of procedural failure after coronary angioplasty, often because of the inability to recanalize the occluded segment with a conventional coronary guidewire. The novel excimer laser catheter described in this report contains a highly efficient, pulsed excimer laser guidewire designed to create a small channel within the occluded coronary segment. A preliminary report of the safety and efficacy of this excimer laser catheter is provided.

METHODS

Ten patients with refractory coronary occlusions that could not be crossed by experienced operators using conventional guidewire techniques were treated using a novel laser catheter system. The laser catheter consisted of a densely packed, multiple fiber, helical guidewire measuring 0.020 inches (0.51 mm) in diameter, interfacing a 308 nm excimer laser system and delivering 70-80 mJ/mm2 of energy to the output surface. After the laser guidewire had been advanced to the occlusion site, laser energy was applied to ablate a channel as the wire was advanced through the occlusion. Once the occlusion had been recanalized, standard concentric laser or balloon angioplasty was performed.

RESULTS

Complete recanalization was achieved in three total occlusions, and partial recanalization was established in a further three; thus, normal coronary perfusion was attained in six out of 10 patients after adjunct excimer laser or balloon angioplasty. The final minimum lumen diameter averaged 1.51 mm and the final residual stenosis diameter was 27%. In two patients the procedure was unsuccessful but without significant complications; two other patients developed limited coronary perforations without clinical sequelae.

CONCLUSION

Refractory coronary occlusions were successfully recanalized in six out of 10 patients using a novel excimer laser catheter. Treatment failures in four patients were not associated with major complications, although limited coronary perforation occurred in two patients.

Implantation and recovery of temporary metallic stents in canine coronary arteries

OBJECTIVES

The purpose of this study was to test the feasibility of implanting and retrieving a heat-activated recoverable temporary stent and to determine its effect on the angiographic, gross and histologic appearance of a normal coronary artery wall.

BACKGROUND

Permanent coronary stenting is associated with a significant incidence of thrombosis, bleeding and vascular complications. These may be avoided by temporarily stenting for a period of hours to several days.

METHODS

Seventy-eight stents constructed from the shape-memory nickel-titanium alloy nitinol were deployed by balloon expansion in the coronary arteries of 28 dogs and left in place for up to 6 months. Thirty minutes to 1 week after implantation, 70 stents were recovered by flushing the coronary arteries with 3 to 5 ml of 75 degrees C lactated Ringer solution, with collapse of the stent over a recovery catheter and subsequent withdrawal.

RESULTS

All stents were successfully recovered and removed percutaneously. Mean vessel diameter after stenting was 12 +/- 6% (p < 0.05) greater than baseline diameter. Mean vessel diameter after stent removal remained enlarged (6 +/- 3%, p < 0.05). No angiographic or gross evidence of thrombosis, dissection, embolization, migration or spasm was associated with implantation or recovery. Microscopic examination revealed minor intimal injury in 40 segments (51%). Microscopic focal medial necrosis was associated with mural platelet-fibrin thrombus in 23 stented segments (29%) and media was interrupted in 7 (9%).

CONCLUSIONS

This study demonstrates the feasibility of a new method of temporary stenting that uses the thermoelastic properties of nitinol to permit reliable recovery of the stent in normal canine coronary arteries.

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.

Morphological predictors of acute complications after percutaneous excimer laser coronary angioplasty. Results of a comprehensive angiographic analysis: importance of the eccentricity index

BACKGROUND

Percutaneous excimer laser coronary angioplasty (ELCA) is a new technique for recanalization of arteries obstructed by coronary atherosclerosis. This study was conducted to assess the complication rate and determine the influence of clinical and angiographic characteristics on complications after ELCA.

METHODS AND RESULTS

A detailed, quantitative, angiographic core laboratory analysis of patients undergoing ELCA was performed by two experienced angiographers who were not the primary laser angioplasty operators. Two hundred patients underwent 203 separate procedures on 220 lesions at three medical centers. Laser success was achieved in 180 lesions (81.8%) and procedural success in 199 (90.5%). Emergency coronary artery bypass graft (CABG) was required in five patients (2.5%). One patient suffered a Q wave myocardial infarction; there were no deaths. Also, acute closure and perforation occurred in 10 (4.5%) and three (1.4%) vessels, respectively. Coronary dissections after laser treatment were seen in 36 vessels (16.4%). Multivariate analysis found two independent preprocedural factors related to complications: eccentricity index, which is the percent deviation of the lesion lumen from the center of the artery (p = 0.0007), and proximal vessel diameter (p = 0.033). In addition, an abrupt proximal face of the lesion was associated with angiographic complications by univariate analysis (p = 0.051). Multivariate analysis showed the eccentricity index (p = 0.032) to be the only independent predictor for the occurrence of any one or more of the important complications (emergency CABG, perforation, acute closure, or Q wave myocardial infarction), whereas lesion angle greater than 45 degrees was a significant univariate predictor (p = 0.029). Other predictors of complications with balloon percutaneous transluminal coronary angioplasty, such as increased lesion length, rough edges, calcification, ulceration, and branch point, were not predictive of complications with the excimer laser.

CONCLUSIONS

The degree of lesion eccentricity is the most powerful predictor of complications after ELCA. This and other morphological predictors may be of benefit in the selection of patients for ELCA as well as directing future development of this new technology.

Excimer laser coronary angioplasty: results in restenosis versus de novo coronary lesions. Excimer Laser Coronary Angioplasty Investigators

There is limited information regarding the use of excimer laser coronary angioplasty (ELCA) in patients with restenotic lesions. The purpose of this investigation was to compare the results of ELCA in patients with restenosis following prior PTCA with results obtained in de novo (no restenosis) patients. A retrospective review was obtained of all patients undergoing attempted ELCA at each of the 12 participating clinical investigative centers. There were 620 patients in the prior restenosis group and 949 in the de novo group. Both laser success (88% vs 78%) and procedural success (92% vs 88%) were higher in restenosis lesions compared with de novo lesions (P less than 0.001). Six-month follow-up was available in 40% of patients. Restenosis occurred in 49% of the prior restenosis group vs 44% of the de novo group (P nonsignificant) but death was more common in the de novo group (2.2 vs 0.4%, P = 0.01). ELCA can be performed with a high success rate in patients with restenosis following prior balloon angioplasty but recurrent restenosis following laser procedure remains a significant problem.

Percutaneous excimer laser coronary angioplasty of lesions not ideal for balloon angioplasty

BACKGROUND

Excimer laser coronary angioplasty is a new, investigational technique for treating coronary artery stenoses. Initial reports have demonstrated acute efficacy and relative safety of this procedure, but have not addressed the effect of lesion type on acute success and complication rates.

METHODS AND RESULTS

In the first 100 patients undergoing percutaneous excimer laser coronary angioplasty at our institution, acute laser success was obtained in 84% and procedural success was obtained in 94%. There were six acute closures during laser angioplasty and one myocardial infarction. Two patients required emergency coronary bypass surgery. Sixty-five percent of patients had lesions not ideal for balloon angioplasty because of lesion morphology (tubular, diffuse, or chronic total occlusion) or ostial location. There were 10 tubular stenoses, 29 diffuse lesions, 18 chronic total occlusions, and eight ostial lesions, including five aorto-ostial lesions. In this nonideal subgroup, the acute success rate with laser was 86% (72% of chronic total occlusions and 91% of non-totally occluded lesions), and the procedural success rate was 94%. There were three acute occlusions during laser angioplasty but no myocardial infarctions, emergency bypass surgeries, or deaths. One coronary artery perforation occurred without clinical sequelae. Laser angioplasty was successful in four of six lesions (67%) in which balloon angioplasty had failed. Laser success was obtained in 10 of 11 (91%) moderately or heavily calcified stenoses. Eight eccentric lesions and two lesions on bends were successfully treated without dissection or perforation. No side branch occlusions occurred in the 15 patients in whom one or more major branches originated within the lesion treated. Adjunctive balloon angioplasty was performed in 47% of cases, usually to obtain a larger final luminal diameter. Need for adjunctive balloon angioplasty decreased to 36% after a larger (2.0 mm) laser catheter became available. Twenty-eight percent of the 105 lesions treated were American College of Cardiology/American Heart Association classification type A, 47% were type B, and 25% were type C. Laser and procedural successes were obtained in 83% and 97% of type A, 88% and 96% of type B, and 85% and 88% of type C lesions, respectively.

CONCLUSIONS

In our initial experience, excimer laser angioplasty was found to be acutely effective and safe therapy for lesions identified as not ideal for balloon angioplasty. This technique may provide a useful adjunct or alternative to balloon angioplasty in selected patients.

Synchronized coronary venous retroperfusion for support and salvage of ischemic myocardium during elective and failed angioplasty

To determine the safety and efficacy of synchronized coronary venous retroperfusion during brief periods of ischemia, 30 patients undergoing angioplasty of the left anterior descending coronary artery were studied. Each patient underwent a minimum of two angioplasty balloon inflations. Alternate dilations were supported with retroperfusion; the unsupported inflations served as the control inflations. Synchronized retroperfusion was performed by pumping autologous femoral artery blood by means of an electrocardiogram-triggered retroperfusion pump into the great cardiac vein through a triple lumen 8.5F balloon-tipped retroperfusion catheter inserted percutaneously from the right internal jugular vein. Clinical symptoms, hemodynamics and two-dimensional echocardiographic wall motion abnormalities were analyzed. Retroperfusion was associated with a lower angina severity score (0.8 +/- 1 vs. 1.2 +/- 1) and delay in onset of angina (53 +/- 31 vs. 37 +/- 14 s; p less than 0.05) compared with the control inflations. The magnitude of ST segment change was 0.11 +/- 0.14 mV with retroperfusion and 0.16 +/- 0.17 mV without treatment (p less than 0.05). The severity of left ventricular wall motion abnormality was also significantly (p less than 0.01) reduced with retroperfusion compared with control (0.7 +/- 1.4 [hypokinesia] vs. -0.3 +/- 1.6 [dyskinesia]). There were no significant changes in hemodynamics, except in mean coronary venous pressure, which increased from 8 +/- 3 mm Hg at baseline to 13 +/- 6 mm Hg with retroperfusion. Four patients required prolonged retroperfusion for treatment of angioplasty-induced complications. The mean retroperfusion duration in these patients was 4 +/- 2 h (range 2 to 7). In the three patients who underwent emergency bypass surgery, the coronary sinus was directly visualized during surgery and found to be without significant injury. There were no major complications. Minor adverse effects were transient atrial fibrillation (n = 2), jugular venous catheter insertion site hematomas (n = 4) and atrial wall staining (n = 1), all of which subsided spontaneously. Thus, retroperfusion significantly reduced and delayed the onset of coronary angioplasty-induced myocardial ischemia and provided effective supportive therapy for failed and complicated angioplasty.

Initiating events of acute coronary arterial occlusion

Acute myocardial infarction is caused by coronary thrombosis on an ulcerated atheroma. We now believe that the predominant cause of this intimal disruption is the rupture of the atheroma through the intimal surface, caused by enzymes released by activated macrophages. The subsequent clinical course following atheroma disruption is determined by the rate and size of thrombus formation. Partially occlusive thrombi produce unstable angina; completely occlusive thrombi produce myocardial infarction; clot embolization can produce sudden death. The localized thrombus lyses within days. The healing process, however, is frequently accompanied by rapid local progression of the size of the atheroma at the site of intimal disruption. With healing of the intimal surface, the patient's clinical status stabilizes. Thus coronary disease is a cyclical phenomenon driven by cellular events within the atheroma and by the interaction of the atheroma with circulating blood elements.

Percutaneous excimer laser coronary angioplasty

To determine the efficacy of percutaneous excimer laser coronary angioplasty as an adjunct or alternative to conventional balloon angioplasty, 55 patients were studied in a multicenter trial. These patients underwent the procedure using a modification of conventional balloon angioplasty technique. A first-generation, 1.6-mm diameter catheter constructed of 12 individual silica fibers concentrically arranged around a guidewire lumen was used. Catheter tip energy density varied from 35 to 50 mJ/mm2. The mean number of pulses delivered at 20 Hz was 1,272 +/- 1,345. Acute success was defined as a greater than or equal to 20% increase in stenotic diameter and a lumen of greater than or equal to 1 mm in diameter after laser treatment. Acute success was achieved in 46 of 55 (84%) patients. Adjunctive balloon angioplasty was performed on 41 patients (75%). The percent diameter stenosis as determined by quantitative angiography decreased from a baseline of 83 +/- 14 to 49 +/- 11% after laser treatment and to 38 +/- 12% in patients undergoing adjunctive balloon angioplasty. The mean minimal stenotic diameter increased from a baseline of 0.5 +/- 0.4 to 1.6 +/- 0.5 mm after laser treatment and to 2.1 +/- 0.5 mm after balloon angioplasty. There were no deaths and no vascular perforations. One patient (1.8%) required emergency coronary bypass surgery. These data suggest that excimer laser energy delivered percutaneously by specially constructed catheters can safely ablate atheroma and reduce coronary stenoses.