Recanalization of femoropopliteal occlusive pathology in patients with peripheral arterial disease (PAD) persists as a significant clinical issue in terms of persistent pain as well as the risk of ischemic limb loss. There are approximately 8.5 million individuals with PAD in the United States,1 and it is estimated that chronic total occlusion (CTO) is present in up to 40% of patients with symptomatic PAD.2 Initial guidewire passage required to perform successful intervention on the atherosclerotic segment becomes more difficult with the occurrence of CTO. Attempted guidewire passage in CTO lesions results in failure in 26% to 95% of cases in various studies.3-6 Upon failed true lumen guidewire passage, subintimal navigation with true lumen re-entry is attempted. Subintimal recanalization with guidewire and standard catheter techniques may be applied, as well as the introduction of a variety of true lumen re-entry devices that incorporate approaches such as high-speed diamond-coated tips, high-frequency vibrating tips, rotating mechanical cutters, and blunt tip microcatheters.
In one initial report, true lumen re-entry in attempted subintimal crossing was unsuccessful with standard catheter and wire techniques in 26% of cases;3 however, re-entry devices allowed successful subsequent crossing in all cases. Another retrospective review of 249 patients with CTO demonstrated that attempted subintimal recanalization of femoropopliteal CTO with a re-entry device was successful in 64.5% of cases.7 Significant calcification at the proposed re-entry site was a strong predictor of failure.
Subintimal dissection and re-entry techniques, while often necessary to address peripheral chronic occlusions, are unsuccessful in a fraction of calcified lesions. In addition, an ability to preserve innate arterial anatomic architecture via intraluminal versus subintimal recanalization contains physiologic appeal, if it may be performed successfully. A simplified technique and device to approach intraluminal guidewire placement through severe, peripheral arterial atherosclerotic lesions is described. A catheter containing an everting inner lumen and a distal centering balloon imparts hydraulic pressure to drive a central guidewire through the lesion under mechanical control of the operator. Once guidewire placement is achieved, angioplasty, stent placement, or atherectomy may be performed in a true lumen fashion.
Everting balloon catheters have been previously applied to treat peripheral atherosclerotic narrowing. One such catheter everted a closed-ended balloon through an arterial lesion, partially dilating the stenosis as it advanced through the lesion.8 The unrolling front of the everting balloon negotiated its path through the residual lumen without prior placement of a guidewire. Full pressurization of the everted balloon achieved therapeutic angioplasty of the stricture. Since this everting balloon catheter incorporated no provision for guidewire use, it is not applicable to current intravascular interventional techniques. More recently, a specialized balloon catheter with a dual pressure inflation system was introduced that cyclically gripped and advanced a guidewire in 3 mm increments to cross an atherosclerotic lesion.9
The Houdini Catheter is a balloon catheter that is inflated to center and anchors its distal tip in the arterial lumen proximal to the lesion, while driving a guidewire through the lesion to access distal vasculature. The construction of the device is depicted in Figure 1. The 5 Fr catheter shaft contains a distal coaxial non-compliant anchor balloon. A 20 cm long, thin-walled section of the inner lumen lies within the distal portion of the catheter; the inner lumen accommodates a 0.014" to 0.035" diameter guidewire. A Y-fitting is attached to the proximal end of the catheter, and a corresponding Y-fitting is connected to the inner lumen, which extends proximally out of the catheter at a distance of 20 cm.
Inflation of the balloon via the Y-fitting on the catheter simultaneously anchors the distal tip of the catheter and compresses the inner lumen against the guidewire. Figure 2 shows the sequence of steps associated with the use of the catheter to access discrete regions of the vasculature distal to an occlusive lesion. If attempted guidewire passage is unsuccessful in a diseased segment of lower extremity vasculature, the catheter is loaded onto the guidewire such that the distal tip of the guidewire is flush with the distal catheter tip. In (A), the catheter is advanced to the lesion, and pressurization of the catheter to 6 atm using an inflator device centers and anchors the catheter tip in the vessel lumen. The intraluminal pressure in the catheter compresses a 20 cm length of inner lumen against the guidewire. In (B), advancement of the proximal, inner lumen Y-fitting while holding the distal, catheter Y-fitting stationary causes eversion of the inner lumen out of the distal catheter tip, driving the guidewire into the lesion. In (C), continued advancement of the proximal Y-fitting relative to the distal Y-fitting causes further advancement through the lesion by the everting inner lumen and the guidewire. Note that the length of guidewire protruding distal to the inner lumen is equal to the length of inner lumen everted from the tip of the catheter.
The functional mechanics of the everting inner lumen concept that allow the device to achieve guidewire recanalization of critical occlusive arterial lesions are illustrated in Figure 3. In its uninflated state as shown in (A), the guidewire is free to move within the inner lumen. When the catheter is inflated to 6 atm of pressure, shown in (B), the 20 cm long, thin-walled section of inner lumen collapses onto the guidewire. If the guidewire is 0.035" in diameter, the grip force exerted on the guidewire equals [surface area of a 20 cm length of 0.035" guidewire] × [88.2 psi (= 6 atm)] = 76.3 lbs. This grip force is exerted at the distal tip of the catheter, at the site of guidewire entry into the hard cap. The resultant effect, as shown in (C), is equivalent to the clinician being able to grip the guidewire at the site of an occlusion with a force of 76.3 lbs.
In conventional catheter systems, a flexible, catheter-supported guidewire is manipulated from a remote puncture site that may be 40 cm or 60 cm away from the lesion. Force exerted over such a significant length of flexible guidewire and flexible coaxial catheter leads to a loss of column strength and guidewire tip crossing force. In the everting inner lumen concept, lumenal eversion and guidewire advancement are performed manually and only occur upon translational movement of the proximal Y-fitting in a controlled fashion. The system functions as a hydraulic-powered probe that is anchored and centered within the vessel lumen. As the guidewire protrudes into the occlusion, the everting inner lumen follows behind the guidewire, dilating the surrounding luminal tract to a 1.4 mm diameter. Following guidewire passage through the lesion, the catheter is deflated and removed from the patient, maintaining guidewire position for subsequent adjunctive therapy such as stent placement or atherectomy.
Guidewire position at the start of the procedure is a function of the morphology of the lesion. If a residual lumen exists in a segment of atherosclerotic narrowing, the guidewire may be retracted back into the inner lumen, such that the everting inner lumen traverses the stenosis without guidewire protrusion. As shown in Figures 4B and 4C, upon pressurization of the catheter and advancement of the proximal Y-fitting, the inner lumen everts from its center outwards, unrolling along the contours of the stenosis in a manner similar to carpet unrolling across the floor. There is limited relative movement or shear force exerted between the surface of the everting inner lumen and the surface of the atherosclerotic lesion. Rather, the everting lumen finds the path of least resistance through the stenosis, which in this case is the residual lumen.
In a previous study, measurable shear force exerted by an everting balloon during passage in a tight stenosis may be up to 40 times less than the shear force observed with coaxial catheter passage.10 On the other hand, if no residual lumen is present, and the leading edge of the lesion is characterized by a calcified hard cap, the straight end of the guidewire is positioned a few mm distal to the tip of the catheter at the start of the procedure. This arrangement fully employs the hydraulic power of the pressurized inner lumen to drive the guidewire directly through the hard cap as the inner lumen is everted through the lesion.
A 55-year-old man was referred to us with a 5-month history of a non-healing venous stasis ulcer of the right ankle, which had failed a trial of Unna boot therapy and a variety of topical wound agents at the local wound care center. The man was a heavy smoker with a history of hypertension, hyperlipidemia, morbid obesity, and peripheral vascular disease status after previous left superficial femoral artery (SFA) angioplasty and bilateral external iliac stents for claudication.
The patient reported right calf claudication with 100 yards of walking and denied symptoms of rest pain. Examination revealed a palpable right femoral pulse with absent popliteal and pedal pulses and a typical 2 cm venous stasis ulcer of the medial ankle with poor quality granulations. His ankle brachial index on the right was 0.46 with monophasic Doppler signals at the popliteal and pedal level. Pulse volume tracings were consistent with SFA occlusion with possible tibial disease.
Comprehensive arteriography demonstrated a patent aorto iliac segment with restenosis of his right external iliac stent. Run-off views showed patency of the first few centimeters of the SFA, which was then occluded through its entire length. The above-knee popliteal artery reconstituted through profunda collaterals with 3-vessel run off to the foot. A 6 Fr Rabbe sheath was positioned in the right common iliac artery, and the restenosis in the external iliac stent was treated with a 7.0/40 drug-eluting balloon.
The sheath was then advanced into the proximal SFA. The initial attempt to cross the CTO was unsuccessful with a stiff angled glidewire and Quickcross catheter. We then selected a 5 mm Houdini device, which was positioned close to the proximal end of the CTO and crossed the lesion quite easily with a V-18 wire. The lesion was then treated with 5.0/120 and 5.0/60 drug-eluting balloons. The total treated length was approximately 16 cm total occlusion. Completion angiography showed a widely patent SFA with excellent distal flow. No stents were used. Following the procedure, the patients had a strongly palpable posterior tibial pulse.
The patient continued to be followed by his local wound care center and the ulcer was healed over the next 2 months. On his 6-month follow-up visit, his ulcer remained healed and his angioplasty remained widely patent with an ankle brachial index of 0.8. He denied symptoms of intermittent claudication but continues to smoke.
Disclosure: The authors have completed and returned the ICMJE Form for disclosure of potential conflicts of interest. Dr Chin reports personal fees from Cruzar Medsystems, Inc., during the study; personal fees from Cruzar Medsystems, Inc., outside the submitted work. In addition, Dr Chin has a patent 9,795,408 issued, a patent 9,326,790 issued, a patent 8,926,559 issued, a patent 20180125510 pending, and a patent 20170360475 pending. Dr Pomposelli discloses paid consulting for Cruzar Med Systems, Inc..
Manuscript submitted on May 3, 2018; accepted on May 22, 2018.
Address for correspondence: Albert K. Chin, MD, Chief Medical Officer, Cruzar Medsystems, Inc, 1100 Industrial Road, Suite 16, San Carlos, California, United States. Email: firstname.lastname@example.org
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