Abstract
Excimer laser coronary atherectomy (ELCA) has been used for coronary intervention for more than 20 years. Advances in delivery systems for laser energy using the xenon-chlorine pulsed laser catheter deliver higher energy density with lower heat production. The Spectranetics CVX-300 (Spectranetics, Colorado Springs, CO, USA) excimer laser catheter system has been used for the treatment of complex coronary lesions. We report our experience with the use of this advanced system for stenoses for which were unsuitable for standard percutaneous coronary intervention; for example, balloon-resistant lesions, chronic total occlusions, and for underexpanded stents in calcified lesions. ELCA may also be valuable for thrombus-containing lesion. We find ELCA to be indispensable in the catheterization laboratory for specific complex or calcified lesions. Its role should be explored in a large randomized trial of thrombus containing lesions and saphenous vein grafts.
1
Introduction
The US Food and Drug Administration-approved laser technology for coronary use in 1992 for the following indications: (1) debulking of saphenous vein grafts (SVG), (2) ostial lesions, (3) eccentric lesions, (4) long lesions (>20 mm), (5) total occlusions crossable by a guide wire, (6) moderately calcified lesions, (7) balloon refractory lesions, and (8) in-stent restenosis (ISR). The ensuing 18 years have seen advances in our understanding of the technology and in the development of this technology.
The Spectranetics CVX-300 (Spectranetics, Colorado Springs, CO, USA) excimer laser coronary angioplasty (ELCA) system compose of excimer laser generator [CVX 300] and the laser catheters 0.9, 1.4, 1.7 and 2-mm pulsed xenon-chlorine laser catheters with either concentric(0.9, 1.4, 1.7, 2 mm) or eccentric (1.7, 2 mm). The eccentric laser catheter features a fibroptic bundle disposed opposite the guide-wire lumen at the catheter tip and a torque mechanism that allows the user to rotate the fiber bundle toward the lesion mass. Most concentric laser catheter are built with the “optimally spaced” (90-μm space among individual fibers) arrangement of fibers which provides improved ablation in comparison to older catheter versions (77 space between fibers) . The laser catheters capable of delivering excimer energy (wave length: 308 nm, pulse length: 185 ns) from 30 to 80 mJ/mm 2 (fluencies) at pulse repetition rates from 25 to 80 Hz. Absorption of excimer laser by tissue may lead to photochemical, photomechanical, or photothermal interactions including formation of gas vapor and acoustic shock waves within the target biologic tissue and creates effects on the non-aqueous components of the irradiated atherosclerotic plaque and its accompanying thrombus.
We report here our recent experience with the Spectranetics laser for a series of lesions unsuitable for standard percutaneous coronary intervention (PCI), including (1) lesions successfully crossed with a guide wire but not with a balloon, (2) calcified lesions, (3) chronic total occlusions, and (4) incompletely expanded stents presenting as ISR in severely calcified lesions. Moreover, in SVG lesions and thrombus containing lesions we found that ELCA effectively vaporizes the thrombus or the friable plaque without distal embolization or slow/no reflow.
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Case 1: Balloon-resistant lesion
An 82-year-old female with a history of hypertension and hyperlipidemia was admitted with dizziness and syncope after an episode of acute diarrhea. She had rapid atrial fibrillation with prolonged sinus pauses after spontaneous conversion. Serum troponin rose to 0.5 ng/ml (normal range 0.0–0.12) and creatinine kinase (CK)-MB to 3 ng/ml (normal range 0.0–2.6).
The patient received 600 mg of clopidogrel and 325 mg of aspirin and underwent coronary angiography. The left coronary system contained no obstructive disease but a severely calcified 95% stenotic lesion was found in the proximal right coronary artery (RCA) ( Fig. 1 A ). A temporary pacer wire was placed in the right ventricle. The diagnostic catheter was exchanged for an 8F hockey stick guiding catheter (Cordis, Miami Lakes, FL, USA) with side holes. Bivalirudin was used as anticoagulation. A 0.014-in. BMW guide wire (Guidant, Santa Clara, CA, USA) crossed the lesion, but 2.5/20-mm and a 1.5/15-mm Sprinter balloons (Medtronic, Minneapolis, MN, USA) did not. The BMW guide wire was exchanged over a micro guide catheter (FineCross MG, Terumo, Ann Arbor, MI, USA) for a Rota Extra Support guide wire (Boston Scientific, Natick, MA, USA). Rotational atherectomy with Rotablator catheters (Boston Scientific) was attempted. A 1.5-mm burr did not cross the lesion and a 1.25-mm burr decelerated without crossing ( Fig. 1 B).
The lesion was successfully crossed with the Spectranetics 0.9-mm excimer laser catheter. Laser energy was initiated with a repetition rate of 40 Hz and fluence of 60 mJ/mm 2 and was then increased to a repetition rate 80 Hz and a fluence of 80 mJ/mm 2 . Subsequent to passage of the laser catheter, rotational atherectomy with 1.5-mm burr was successful. The Rota Extra Support guide wire was exchanged for a BMW guide wire and a 2.5/20-mm Spinter balloon was inflated at 12 atmospheres ( Fig. 1 C). A Micro-Driver 2.5/14-mm bare metal stent (BMS) (Medtronic) was deployed at high pressure (16 atm) ( Fig. 1 D). Echocardiography showed preserved left ventricular function with inferior wall hypokinesis. The patient was discharged four days after admission.
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Case 1: Balloon-resistant lesion
An 82-year-old female with a history of hypertension and hyperlipidemia was admitted with dizziness and syncope after an episode of acute diarrhea. She had rapid atrial fibrillation with prolonged sinus pauses after spontaneous conversion. Serum troponin rose to 0.5 ng/ml (normal range 0.0–0.12) and creatinine kinase (CK)-MB to 3 ng/ml (normal range 0.0–2.6).
The patient received 600 mg of clopidogrel and 325 mg of aspirin and underwent coronary angiography. The left coronary system contained no obstructive disease but a severely calcified 95% stenotic lesion was found in the proximal right coronary artery (RCA) ( Fig. 1 A ). A temporary pacer wire was placed in the right ventricle. The diagnostic catheter was exchanged for an 8F hockey stick guiding catheter (Cordis, Miami Lakes, FL, USA) with side holes. Bivalirudin was used as anticoagulation. A 0.014-in. BMW guide wire (Guidant, Santa Clara, CA, USA) crossed the lesion, but 2.5/20-mm and a 1.5/15-mm Sprinter balloons (Medtronic, Minneapolis, MN, USA) did not. The BMW guide wire was exchanged over a micro guide catheter (FineCross MG, Terumo, Ann Arbor, MI, USA) for a Rota Extra Support guide wire (Boston Scientific, Natick, MA, USA). Rotational atherectomy with Rotablator catheters (Boston Scientific) was attempted. A 1.5-mm burr did not cross the lesion and a 1.25-mm burr decelerated without crossing ( Fig. 1 B).
The lesion was successfully crossed with the Spectranetics 0.9-mm excimer laser catheter. Laser energy was initiated with a repetition rate of 40 Hz and fluence of 60 mJ/mm 2 and was then increased to a repetition rate 80 Hz and a fluence of 80 mJ/mm 2 . Subsequent to passage of the laser catheter, rotational atherectomy with 1.5-mm burr was successful. The Rota Extra Support guide wire was exchanged for a BMW guide wire and a 2.5/20-mm Spinter balloon was inflated at 12 atmospheres ( Fig. 1 C). A Micro-Driver 2.5/14-mm bare metal stent (BMS) (Medtronic) was deployed at high pressure (16 atm) ( Fig. 1 D). Echocardiography showed preserved left ventricular function with inferior wall hypokinesis. The patient was discharged four days after admission.
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Case 2: Chronic total occlusion
A 57-year-old male with a past medical history of hyperlipidemia, hypertension, and tobacco abuse was admitted for elective diagnostic coronary catheterization because of chest pain and inferior wall ischemia on myocardial scintigraphy. The left coronary system was free of obstructive disease, but there was total occlusion in the proximal third of the RCA ( Fig. 2 A ). The diagnostic catheter was exchanged for a 7F 3D right guiding catheter. The occlusion could not be crossed with a MiracleBros 6 guide wire (Abbott Vascular, Abbott Park, IL, USA); however, successful crossing was attained with a 2.1F Tornus catheter (Abbott Vascular) and a Confianza guide wire (Abbott Vascular). An Apex 1.5-mm balloon (Boston Scientific, Natick, MA) could not be passed. Initially the Spectranetics excimer laser (0.9 mm) also failed but did cross with the use of a proximal anchoring balloon. Laser treatment with a repetition rate of 80 Hz and a fluence of 80 mJ/mm 2 allowed passage ( Fig. 2 B) of an Apex 1.5/15-mm balloon followed by a 2.5/30-mm Maverick balloon (Boston Scientific). Both were inflated at high pressure, and a long Cypher (2.5/30-mm) drug-eluting stent (DES) (Cordis, Miami Lakes, FL, USA) was deployed at high pressure with excellent angiographic results ( Fig. 2 C).
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Case 3: Underexpanded stents with recurrent restenosis
A 64-year-old male with a past medical history of hypertension, hyperlipidemia, and who was a former heavy smoker presented to our center. Nine years earlier, he developed angina for which he underwent implantation of a 3.0/24 BMS in a significant stenosis in the proximal circumflex coronary artery. Seven months later, he presented with recurrent angina. Diffuse ISR in the proximal circumflex artery was treated with rotational atherectomy, balloon angioplasty, and Irdium-192 radiation to 14 pGy, and a 3.0-mm BMS was implanted. He did well up until 3 years ago. He again had symptomatic ISR: this time he received a 3-mm TAXUS DES (Boston Scientific). One year later, mild exertional angina reappeared and lateral ischemia was demonstrated on myocardial scintigraphy. Coronary angiogram revealed focal ISR in the proximal circumflex artery of the multiple overlapped stents ( Fig. 3 A ). Intravascular ultrasound showed underexpanded stents in an area of severe underlying concentric calcification. Minimal luminal area was 1.3 mm 2 ( Fig. 3 B). Multiple attempts at dilatation with non-complaint balloons at pressures up to 24 atmospheres failed. The stenosis was then treated with a concentric 2-mm excimer laser ( Fig. 3 C), followed by high pressure Quantum balloon (Boston Scientific) inflation (28 atmospheres) ( Fig. 3 D) with good angiographic and ultrasound results ( Fig. 3 E and F), thereby increasing the minimal luminal area to 3.68 mm 2 .
