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Can’t See the Forest for the Trees: Transcollateral Crossing of Chronic Total OcclusionsVinayak Subramanian, BS1; George L. Adams, MD, MHS2

From 1Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, and 2Rex Hospital, University of North Carolina Health System, Raleigh, NC

ABSTRACT: Chronic Total Occlusions (CTOs) remain a significant clinical challenge in the treatment of peripheral artery

disease. Successful treatment of CTOs is largely dependent on the skill level, patience, and experience of the

interventionalist and is associated with a success rate between 34% and 91%. A transcollateral approach can be

taken to cross and treat complex lesions that are untreatable using traditional techniques. This paper is focused on

the techniques and tools required for successfully using the transcollateral approach to cross CTOs in the peripheral

artery tree.

VASCULAR DISEASE MANAGEMENT 2015;12(6):E109-E113 Key words: transcollateral, chronic total occlusions, peripheral artery disease

Peripheral artery disease (PAD) affects 8 mil-

lion to 12 million Americans. Of the popu-

lation over the age of 65, 12% to 20% is at

risk of developing symptomatic peripheral arterial

insufficiency.1 Chronic total occlusions (CTOs) in

the peripheral artery tree are common; nearly 40%

of PAD cases have CTOs.2 Percutaneous endovascu-

lar intervention has emerged as the preferred meth-

od to restore blood flow to alleviate symptoms of

PAD. However, endovascular treatment of CTOs is

challenging due to the lack of tools for crossing and

treating, time commitment, and skill level. In fact,

treatment of CTOs has a success rate ranging be-

tween 34% and 91%. The interventionalist may uti-

lize various approaches to successfully cross the CTO

in order to treat the lesion. An antegrade approach is

the traditional method of crossing a CTO. However,

traditional techniques to recanalize the vessel fail in

20% of all cases.3 Using a different approach such as

the retrograde and/or transcollateral technique may

allow the interventionalist to treat complex lesions

that are untreatable by traditional techniques. This

paper will focus on the utilization of transcollaterals

to cross infrainguinal CTOs.

COLLATERAL ARTERIESPeripheral arterial collaterals develop to shunt blood

around a chronic total occlusion, first described by

Longland in 1953.4 Commonly recognized, infrain-

guinal collateral vessels are paired with their respec-

tive main vessel occlusion (profunda collateral and

superficial femoral artery [SFA] occlusion; geniculate

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collateral and popliteal occlusion; peroneal collateral

and tibial occlusion; plantar loop collateral and dorsalis

pedis or plantar occlusion) (Figures 1-4). These col-

laterals serve to provide the metabolic nutrients to the

distal vasculature. However, when these collaterals do

not fulfill the needs of the distal vasculature, symptoms

develop in the form of claudication and at its worst

critical limb ischemia.5 If symptoms develop, opening

the chronic total occlusion is warranted to provide in-

line blood flow. Many times an antegrade approach is

unsuccessful and the operator will consider other av-

enues to cross the lesion.6,7 A transcollateral approach is

Figure 1.Treating a chronic total occlusion lesion in the superficial femoral artery by utilizing the profunda collaterals. A wrapping wire technique is employed in order to deploy interventional tools from an antegrade approach after crossing the lesion transcollaterally.

Figure 3. Transcollateral crossing of the posterior communicating artery from the peroneal to the posterior tibial artery.

Figure 2. Transcollateral revascularization of a posterior tibial chronic total occlusion using geniculate collaterals. Successful crossing is followed by percutaneous transluminal angioplasty.

Figure 4. The plantar loop collateral from the dorsalis pedis artery is used to successfully cross a chronic total occlusion in the posterior tibial artery.

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an exotic technique that can be used to treat occlusions

regardless of their location in the peripheral arterial tree

without having to gain a second access point.

TREATING CTOS USING A TRANSCOLLATERAL APPROACHWhen the antegrade approach fails in crossing a CTO, a

transcollateral approach may be considered. Angiograph-

ically, multiple angulated views are obtained to delineate

the exact course of the collateral artery considering its

many branches and tortuosity. The collateral vessel is ini-

tially treated with vasodilators, considering its tapering

size (many times less than 1 mm) and to reduce vaso-

spasm.8 Additionally, the patient is anticoagulated with

heparin with a goal activated clotting time ≥250. A floppy

tipped 300 cm hydrophilic wire is then advanced through

the collateral artery and positioned such that the tip of

the wire is at the distal cap of the CTO and is facing in

a retrograde fashion. A 0.014˝/0.018˝ 150 cm crossing

catheter is inserted over the wire and advanced to the

distal cap. The floppy tipped wire is then exchanged for

a 0.014˝/0.018˝ CTO wire, which is used to cross the

occlusion. Longer length wires, and long-shaft percuta-

neous transluminal angioplasty (PTA) balloons are pre-

ferred when treating from the transcollateral approach.

The paucity of long, and low profile interventional tools

place a significant limitation in treating CTOs from a

transcollateral approach when the access point is far from

collateral and the patient is tall.

Retrograde Wire Enters True Lumen

If the CTO wire is able to successfully cross the

occlusion and remain in true lumen, crossing should

be followed up with PTA to treat the occlusion and

recanalize the vessel. This is shown in a patient whose

chronic total occlusion extends from the tibiopero-

neal trunk into the proximal posterior tibial artery

(Figure 2). An antegrade approach is attempted to

cross the lesion but the chronic total occlusion wire

enters a subintimal plane jeopardizing the ostium of

the anterior tibial artery. Therefore, a transcollateral

approach is attempted through a tortuous geniculate

artery which starts in the mid popliteal and extends

to the proximal posterior tibial. The collateral is suc-

cessfully traversed with a long, floppy, hydrophilic

wire supported by a low-profile crossing catheter.

The benign wire is switched for an 18g CTO wire

and successfully crossed into the true lumen. Balloon

angioplasty is then performed through the collateral

with a low profile balloon successfully recanalizing

the tibial-peroneal trunk and posterior tibial artery.

If the collateral is too small and/or tortuous to ad-

vance a balloon, then a wrapping wire technique

should be performed. (Figure 1C) This is illustrated

in a patient with a CTO of the SFA and a transcol-

lateral approach through the profunda artery is per-

formed. The collateral is too small to advance a bal-

loon, therefore a second wire is placed in an antegrade

fashion. The antegrade wire uses the retrograde wire

as a guide. Wires have a natural affinity for each other,

and as such the antegrade wire wraps the retrograde

wire, advancing until the antegrade wire successfully

crosses the CTO. Then treatment can be performed

in an antegrade fashion as illustrated in Figure 1,

recanalizing the SFA.

Antegrade and Retrograde Wires Enter Subintimal Planes

If the antegrade wire followed by the retrograde

transcollateral wire enters two different subintimal

planes, a double balloon technique can be used to

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fenestrate the two lumens of the vessel (Figure 5).

To do this, both antegrade and retrograde wires are

advanced using multiple angiographic views to ensure

that the wires are no more 2-3 mm apart.9 PTA bal-

loons are advanced over each wire, abutting the tips of

the balloons. Both balloons are inflated simultaneously,

successfully fenestrating the lumen at the tips of the

balloon.10 The antegrade wire is then advanced into

the retrograde channel and distally into true lumen.

The retrograde equipment is then removed and the

vessel is treated from an antegrade fashion.

Tools Required to Treat CTOs

Utilizing the transcollateral approach to treat CTOs

requires specialized tools that are capable of being de-

ployed in smaller vessels while being able to provide

support as the interventionalist maneuvers through

the collateral channels and re-enters the native vessel.

Longer length, flexible interventional tools are re-

quired to successfully cross and treat CTOs using the

transcollateral approach. Floppy tipped, strong-bodied

wires and low-profile support catheters are desirable

when using the transcollateral approach. In addition,

stiff-tipped, polymer-coated CTO wires are prefer-

able when crossing CTOs. Treating CTOs using this

approach requires flexible PTA balloons that are low

profile with long shaft lengths. Development of new

interventional tools that are designed to be used for

transcollateral crossing will give interventionalists a

wider array of tools to choose from thereby enhanc-

ing the chances of success.

CONCLUSIONTreatment of CTOs is a critical challenge, and ad-

vanced techniques such as transcollateral crossing may

enhance the chances of successful recanalization. Uti-

lizing the transcollateral approach may allow clini-

cians to cross and treat lesions that are untreatable by

traditional approaches and thereby improve patient

outcomes. Few interventional tools exist that can be

successfully used in conjunction with a transcollateral

approach. Development of new tools can enhance

techniques available to interventionalists. Clinicians

Figure 5. Schematic of double balloon technique to re-enter true lumen after entering a subintimal plane. Shear forces generated by balloons creates a fenestration in the subintimal plane, thus allowing for re-entry into true lumen.

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need to invest time to gain the appropriate training to

successfully use advanced techniques and add transcol-

lateral crossing of CTOs to their arsenal of techniques

to cross CTOs. n

Editor’s note: Disclosure: The authors have completed

and returned the ICMJE Form for Disclosure of Potential

Conflicts of Interest. The authors report no disclosures related

to the content herein.

Manuscript received January 22, 2015; manuscript accepted

March 10, 2015.

Address for correspondence: George L. Adams, MD, Rex

Healthcare, 300 Health Park Drive, Suite 110, Garner,

NC 27529 United States. Email: adamsgla@hotmail.com.

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