In vivo canine coronary artery laser irradiation: photodynamic therapy using dihematoporphyrin ether and 632 nm laser. A safety and dose-response relationship study

The changing face of vascular interventional radiology: the future role of pharmacotherapies and molecular imaging

Interventional radiology has had to evolve constantly because there is the ever-present competition and threat from other specialties within medicine, surgery, and research. The development of new technologies, techniques, and therapies is vital to broaden the horizon of interventional radiology and to ensure its continued success in the future. In part, this change will be due to improved chronic disease prevention altering what we treat and in whom. The most important of these strategies are the therapeutic use of statins, Beta-blockers, angiotensin-converting enzyme inhibitors, and substances that interfere with mast cell degeneration. Molecular imaging and therapeutic strategies will move away from conventional techniques and nano and microparticle molecular technology, tissue factor imaging, gene therapy, endothelial progenitor cells, and photodynamic therapy will become an important part of interventional radiology of the future. This review looks at these new and exciting technologies.

A first trial in the clinical application of photodynamic therapy for the prevention of restenosis after coronary-stent placement

BACKGROUND AND OBJECTIVES

The aim of this clinical study was to evaluate the safety of local delivery of a photosensitizer followed by photodynamic therapy (PDT), to determine its effectiveness in reducing in-stent restenosis.

STUDY DESIGN/PATIENTS AND METHODS

Porfimer sodium was administered via a local delivery catheter to five coronary-stent implanted lesions followed by irradiation with a pulse laser. Coronary angiography (CAG) was performed at the baseline, after the procedure and at a 6-month follow-up.

RESULTS

By the 18-month clinical follow-up, no adverse events such as photodermatosis, or myocardial ischemia had occurred. At the follow-up, no coronary embolization, dissection, or aneurysmal dilatation was observed in the CAG. In-stent diameter stenosis, late loss, and loss index were 19.16+/-8.20%, 0.37+/-0.18 mm, and 0.19+/-0.12, respectively. No in-stent restenosis was observed.

CONCLUSIONS

This study suggests that PDT, with local delivery of Porfimer sodium, is safe and may be a feasible technique in preventing in-stent restenosis.

Phase I drug and light dose-escalation trial of motexafin lutetium and far red light activation (phototherapy) in subjects with coronary artery disease undergoing percutaneous coronary intervention and stent deployment: procedural and long-term results

BACKGROUND

Motexafin lutetium (MLu; Antrin) is a photosensitizer that is taken up by atherosclerotic plaque and concentrated within macrophages and vascular smooth muscle cells. After photoactivation with far red light, MLu facilitates production of cytotoxic oxygen radicals that mediate apoptosis. We assessed the safety and tolerability of phototherapy (PT) with MLu in patients undergoing percutaneous coronary intervention with stent deployment.

METHODS AND RESULTS

An open-label, phase I, drug and light dose-escalation clinical trial of MLu PT enrolled 80 patients undergoing de novo coronary stent deployment. MLu was administered to 79 patients by intravenous infusion 18 to 24 hours before procedure, and photoactivation was performed after balloon predilatation and before stent deployment. Clinical evaluation, serial quantitative angiography, and intravascular ultrasound were performed periprocedurally and at 6 months follow-up. MLu PT was well tolerated without serious dose-limiting toxicities, and side effects (paresthesia and rash) were minor. No adverse angiographic outcomes were attributed to phototherapy.

CONCLUSIONS

This study demonstrates that coronary MLu PT seems safe, and the maximum well-tolerated MLu dose and range of tolerated light doses were identified. These data can be used in phase II efficacy trials of MLu PT for the treatment of coronary atherosclerosis or vulnerable plaque.

New catheter-based technology for the treatment of restenosis

Catheter-based vascular interventions have been in development worldwide for several decades, leading to remarkable progress in device technology. Mechanical interventional devices, such as angioplasty balloons, atherectomy devices, and stents, were invented and have contributed greatly to the treatment of atherosclerotic vascular stenosis. However, mechanical approaches do not effectively prevent subsequent intimal growth. Recently, several biological approaches, including radiation therapy and drug-eluting stents, have shown striking inhibition of intimal growth. These significant results are likely to change the treatment strategy in the field of interventional cardiology. Furthermore, additional catheter-based technologies for vascular interventions are presently being evaluated. These latest technologies designed to prevent intimal proliferation include intravascular sonotherapy, cryotherapy, photoangioplasty, and soft X ray. To date, intravascular sonotherapy has proven its efficacy in animal studies and safety in human studies. Cryotherapy, the application of cold thermal energy during angioplasty, enhances the acute effects of conventional dilation while decreasing the likelihood of restenosis. Photoangioplasty has a unique property based on its selective mechanism of action to treat atheromatous plaque. Soft X ray systems provide convenient device handling and well-controlled radiation dose. Some of these technologies may play an important role in vascular interventions in the near future.

Photoangioplasty: An emerging clinical cardiovascular role for photodynamic therapy

Photodynamic therapy (PDT) has been studied and applied to various disease processes. The potential of PDT for selective destruction of target tissues is especially appealing in cardiovascular disease, in which other existing interventional tools are somewhat nonselective and carry substantial risk of damage to the normal arterial wall. Enthusiasm for photoangioplasty (PDT of vascular de novo atherosclerotic and, potentially, restenotic lesions) is fueled by more effective second-generation photosensitizers and technological advances in endovascular light delivery. This excitement revolves around at least 4 significant attributes of light-activated therapy: the putative selectivity and safety of photoangioplasty, the potential for atraumatic and effective debulking of atheromatous plaque through a biological mechanism, the postulated capability to reduce or inhibit restenosis, and the potential to treat long segments of abnormal vessel by simply using fibers with longer light-emitting regions. The available nonclinical data, coupled with the observations of a new phase I trial in human peripheral atherosclerosis, suggest a promising future for photoangioplasty in the treatment of primary atherosclerosis and prevention of restenosis.

Photodynamic therapy of atherosclerosis using YAG-OPO laser and Porfimer sodium, and comparison with using argon-dye laser

We performed photodynamic therapy (PDT) using the Yttrium Aluminium Garnet-Optical Parametric Oscillated (YAG-OPO) laser in cases of atherosclerosis, and examined its efficacy in vivo. We also performed PDT using an Argon-dye (Ar-dye) laser with the same output, and compared the efficacies. Following balloon denudation injury of the thoracoabdominal aorta, rabbits were raised on a cholesterol diet for 16 weeks, producing atheroma in that region. At 24 h following the administration of Photofrin 5 mg/kg, PDT was performed, and animals were sacrificed at 1 day, 1 week, and 2 weeks following the procedure to examine its efficacy. This was compared with the efficacy of PDT using the Ar-dye laser. Following PDT using a YAG-OPO laser, an increase in the vessel lumen was seen due to reduction of the hypertrophic intima and media, without the appearance of inflammatory cells. This result was seen more strongly in PDT using the pulse wave YAG-OPO laser than with the continuous wave Ar-dye laser, affecting not just the intima but also the media. These data demonstrated that PDT can effectively regress atherosclerotic lesions.

Cardiovascular applications of laser technology

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrhythmias and/or laser diagnostics are directed at improving upon conventional non-laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy.