Section B
Treatment of Lesions Resistant to Dilation
Although less common than failure to cross a CTO lesion with a guidewire, occasionally a coronary lesion cannot be crossed with a balloon or cannot be dilated with a balloon. It is important to confirm that the guidewire is in the vessel architecture or in the distal true lumen before proceeding with any over-the-wire catheter or before applying various dilation strategies. The vessel architecture can usually be determined by observing calcium deposits or other signs of the vessel outline moving or “dancing” in sync with the interventional guidewire. The distal true lumen can be determined by contralateral angiography.
For cases in which a balloon cannot cross the lesion, the initial step is to advance a small (1.2–1.5 mm in diameter) balloon as deep as possible into the lesion to modify the proximal cap. When using small balloons, it is important to use longer length balloons (15–20 mm) because the largest profile of these balloons is at the mid shaft marker and the balloon tip will often penetrate the occlusion and stop at the marker. At this point, the balloon can be inflated to high pressure (14–16 atm) to determine if the lesion can be crossed from proximal to distal. If this fails, the next maneuver is to intentionally rupture the small balloon so as to modify the morphology of the proximal vessel/cap. If this fails to enable crossing then either a Corsair catheter, Asahi Intecc, (Nagoya, Japan) for more tortuous or less calcified lesions, or the Tornus catheter (Asahi Intecc) for more calcified lesions with shorter proximal stumps can be used.42 This is followed by maneuvers that can increase guide catheter support, such as use of guide catheter extensions43 or anchor techniques.4 Occasionally, a FineCross (Terumo, Somerset, New Jersey) or Valet (Volcano, Rancho Cordova, California) catheter may be able to cross lesions that the Corsair and Tornus catheters could not. The catheters can be rotated to facilitate their passage, as this will reduce friction within the vessel.
If these maneuvers fail then more aggressive techniques, such as the use of coronary laser,44 rotational atherectomy,45 and the Crosser catheter, FlowCardia Inc. (Bard, Peripheral Vascular, Tempte, AZ)46 can be employed. Rotational atherectomy and the Crosser catheter can be used even when the wire is not in the distal lumen but still in the vessel architecture. Small burrs (usually 1.25 mm and no larger than 1.5 mm) can be used to modify the proximal vessel architecture, which may allow the base of operations (i.e. the over-the-wire catheter) to be moved to a more advantageous location. However, rotational atherectomy requires exchanging the guidewire, which can be accomplished by exchanging through an over-the-wire balloon or microcatheter. In situations where the distal true lumen has not been reached, the last 2 cm of the radiopaque wire tip can be removed prior to placement in the artery, thereby providing further reach with the burr (part of the radiopaque portion of the wire should be preserved to prevent the burr from going off the guidewire). Alternatively, the wire can be looped further down the vessel prior to atherectomy. Rotational atherectomy in the subintimal space should only be attempted by very advanced CTO operators.
Similarly, there are several strategies for lesions resistant to balloon dilation, such as high pressure inflation of non-compliant balloons (with or without buddy wires), the use of cutting balloons or the AngioSculpt (AngioScore, Fremont, CA), the use of the Tornus catheter (Asahi Intecc), rotational atherectomy, and laser.47
If all of these techniques fail to achieve balloon crossing and/or balloon dilation of the lesion then success can often be achieved by recrossing the lesion within the subintimal space either in the antegrade direction using a prolapsed guide wire or CrossBoss catheter with re-entry of the true lumen prior to major branches,48 or using a retrograde approach with retrograde dissection and re-entry to go around the non-crossable or non-dilatable lesion.
The authors would like to thank Ms Sheila Agyeman for her invaluable effort in coordinating the manuscript creation process.