Abstract
Peripheral arterial disease (PAD) is a growing clinical condition affecting more than 10 million patients in the United States and it is responsible for more than 120,000 amputations annually. The presence of chronic total occlusions (CTO) increases the complexity of endovascular procedures and open surgery may often be the preferred approach. Despite the optimization of the CTO devices and technique, percutaneous CTO revascularization remains a challenging procedure even for experienced operators with important complication rates. The Ocelot TM system is a novel CTO device to use real-time optical coherence tomography (OCT) imaging guidance for the recanalization of peripheral CTOs. We review the mechanism of the Ocelot system, the initial results from the multi-center Connect-II trial and two cases of Ocelot-assisted CTO recanalization.
1
Arterial chronic total occlusion of the low extremities
Peripheral arterial disease (PAD) is a growing clinical condition globally with important impact on morbidity and mortality . PAD affects more than 10 million patients in the United States and it is responsible for more than 120,000 amputations annually. Aggressive risk factor modification, smoking cessation, supervised exercise programs and optimal medical therapy may prevent the development of symptoms. However, progressive lifestyle-limiting intermittent claudication and critical limb ischemia warrant supervision by vascular specialists and often percutaneous or surgical revascularization . According to the Trans-Atlantic Inter-Society Consensus (TASC) classification, the presence of chronic total occlusions (CTO) increases the complexity of endovascular procedures and open surgery may often be the preferred approach . A surgical approach may not always be feasible in the presence of multiple co-morbidities which are common in that complex patient subgroup. The optimization of specialized devices for the recanalization of complex arterial lesions has made endovascular approaches a potential alternative to surgery especially in high-risk patients for surgery.
2
Endovascular approaches for lower extremity CTO recanalization
The recanalization of chronic total occlusions carries increased risks for artery dissection, perforation, distal embolization, longer procedural time, radiation and contrast exposure. Over the last years the accumulation of percutaneous experience treating CTOs in coronary and peripheral arteries and the improvement of the device armamentarium have increased the safety of the procedure and minimized the risks of complications. The optimization of the CTO access with antegrade, retrograde or transcollateral approaches and the feasibility of popliteal, tibial, peroneal and dorsalis pedis access offer now a variety of options to the peripheral interventionalists . The STAR (subintimal tracking and re-entry) technique which was initially developed for the treatment of coronary arteries CTOs is increasingly used and specialized devices have been developed for safer re-entry to the true lumen . Specialized CTO devices have been designed using microdissection, vibrational energy and laser to recanalize such challenging lesions with different success rates .
2
Endovascular approaches for lower extremity CTO recanalization
The recanalization of chronic total occlusions carries increased risks for artery dissection, perforation, distal embolization, longer procedural time, radiation and contrast exposure. Over the last years the accumulation of percutaneous experience treating CTOs in coronary and peripheral arteries and the improvement of the device armamentarium have increased the safety of the procedure and minimized the risks of complications. The optimization of the CTO access with antegrade, retrograde or transcollateral approaches and the feasibility of popliteal, tibial, peroneal and dorsalis pedis access offer now a variety of options to the peripheral interventionalists . The STAR (subintimal tracking and re-entry) technique which was initially developed for the treatment of coronary arteries CTOs is increasingly used and specialized devices have been developed for safer re-entry to the true lumen . Specialized CTO devices have been designed using microdissection, vibrational energy and laser to recanalize such challenging lesions with different success rates .
3
Development of a novel OCT-guided CTO catheter — The Ocelot catheter
Optical coherence tomography (OCT) technology uses near-infrared light to optimize intravascular visualization and it has been extensively studied for coronary arterial circulation imaging. The Ocelot TM system is the first CTO device to use real-time OCT for the recanalization of peripheral CTOs ( Fig. 1 ). Ocelot was named after the nocturnal wildcat which is known for its exceptional night vision. The Ocelot over-the-wire catheter has a 110 cm shaft length and it is compatible with 6 F sheaths and 0.014” guidewires. Its distal tip has a 2 mm crossing profile and it consists of spiral flutes and an optical fiber to facilitate catheter advancement in the CTO. It is factory pre-shaped with 3 markers to allow controlled deflection and re-orientation when needed ( Fig. 2 ). The real-time OCT just proximal to the catheter tip allows direct visualization of the catheter position throughout the catheter progress in the CTO without the use of contrast.
