Fig. 7.1
IVUS-guided proximal cap puncture. (a) IVUS of proximal cap. (b) Guidewire entering into proximal cap
Fig. 7.2
(a, b) Scratch and go technique
2.
It is not uncommon for the anatomy to disallow IVUS interrogation, either because there is no appropriately-sized sidebranch, or proximal disease inhibits passage. In addition, heavy calcification (or the presence of a previously placed stent) can make visualization of the cap nearly impossible. In such circumstances, the ambiguous cap can be “ignored” and the entry performed proximal to the ambiguous cap. This approach has several requirements however: because the subintimal space is purposely entered, an ADR strategy must be committed to. This in turn requires the presence of an adequate reentry zone, as well as no significant sized branch (e.g. a diagonal) between the newly formed proximal entry and the body of the CTO (as the branch would not be perfused following successful reentry). Assuming these conditions are met, the two strategies for making a new proximal entry in the coronary are Scratch and Go, and BASE (Balloon Assisted Subintimal Entry).
Scratch and Go (Fig. 7.2) involves gaining entry into the subintimal space proximal to the ambiguous cap by using a Corsair microcatheter and Confianza Pro 12. A long (3–4 mm), sharply angulated bend is made on the wire, which is then used to puncture into the subintimal space over a very short distance (5 mm). This technique will be easier to perform in the presence of a plaque that can be targeted with the wire. The tip of the Corsair is then carefully advanced (rotated) over the wire, which is then exchanged out for a plastic-jacketed wire (usually a Fielder XT, also with an exaggerated bend). The Fielder XT is then purposely knuckled into the subintimal space, and advanced into the body of the CTO, but not beyond the distal cap. The dissection is completed using the CrossBoss catheter, as described in other chapters, with reentry using the Stingray balloon and wire. The manipulation of the Corsair and Confianza Pro 12 in this technique is technically difficult and requires considerable previous experience with both, to prevent excessive wire penetration and/or loss of position. In addition, there are several anatomical characteristics that can render this technique nearly impossible, specifically a large proximal vessel with heavy calcification.
BASE is a more user-friendly version of the same concept (Figs. 7.3 and 7.4, Videos 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 7.10, and 7.11). A balloon (sized about 1:1) is brought into the CTO artery, proximal to the presumed ambiguous cap, and dilated up to high pressures, with the goal of making several dissection planes. Again, this technique is easier to perform when a plaque, even when non-significant, is present. A Corsair is then brought into the artery, again with a plastic jacketed wire (Fielder XT or Pilot 200), and the wire is knuckled into the subintimal space, with advancement and subsequent exchange for the Crossboss as noted above. This is an easier (and somewhat safer) technique to master, but can also be limited by large vessels that are heavily calcified.
Fig. 7.3
(a–d) Balloon-assisted subintimal entry (BASE)
Fig. 7.4
(Videos 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 7.10, and 7.11). Balloon-assisted subintimal entry (BASE) and blind stick techniques. (a, b) More than 20 mm RCA CTO with a very ambiguous proximal cap, with many ipsilateral bridge collaterals (Videos 7.1 and 7.2). (c) Retrograde approach with a Sion through the large epicardial CC from the LCX to the PLV (Video 7.3). (d) Failure to connect into the distal RCA, with subintimal tracking in the last few mm (Video 7.4). (e) Antegrade bailout with the BASE (balloon-assisted subintimal entry). After dilating the proximal RCA segment with a 3.0 mm balloon, a very tiny injection was performed with 1 cc of contrast, showing a dissection plane (Video 7.5). (f) A Fielder XT in knuckled into the dissection plane, with the support of a CrossBoss (Video 7.6). (g) The CrossBoss is advanced to the distal RCA for re-entry (Video 7.7). (h) A Stingray is in place (Circle), but an antegrade hematoma is compressing the true lumen. Suction of blood from the Stingray ports did not improve visualization (Video 7.8). (i) A first stick is performed through the port pointing upward, as the common position of a Stingray following a CrossBoss is following the great curvature of the artery (Video 7.9). (j) Successful “swap” with a Pilot 200 shaped as the Stingray wire (Video 7.10). (k) Final result after DES deployment (Video 7.11)
Ultimately, if these approaches fail, or if the anatomy is not conducive to start with, a retrograde strategy should be applied, if possible.
Impenetrable Cap
This is defined as an inability to gain wire entry into a defined (i.e., non-ambiguous) proximal cap. The solutions include: (1) Maximizing support- this can include the use of anchor balloons and guide extensions. A Corsair should be utilized as the microcatheter of choice, as it will be able to get closer to the tip of the wire (and thus enhance penetration power) than other alternatives. In some situations, a “power position” of the Corsair can be obtained by inflating an appropriately sized balloon in the artery next to the Corsair, thus pinning it and providing even more support for the wire. (2) Use of the stiffest wires available-Confianza Pro 12 is the preferred coronary wire in this scenario, but other wires, including the Stingray wire, the Progress 200 T and peripheral options (if available in one’s lab) can also be successful. (3) If the cap is well defined, and the operator is experienced with use of coronary laser, a 0.9 mm laser catheter can be brought down to the tip of wire and energy applied (without catheter advancement) to allow for modification of the cap and subsequent wire entry. (4) Similarly, hydraulic cap modification can be performed (see Chap. 8): The Corsair catheter is advanced as far as possible over the wire, with the tapered tip hopefully “buried” into the cap. The wire is removed and a small volume of contrast is carefully injected (using a 3 cc syringe), under fluoroscopic guidance. Care must be taken to avoid a large dissection and/or “mushroom cloud” formation. The guidewire is then reintroduced and the modified cap entered.
Any of the previous techniques can be successfully used to proceed with either WE or ADR. However, in many instances, the difficulty in crossing the proximal cap with a wire becomes a predictor of continued significant challenges in advancing all other gear (microcatheters, CrossBoss, Stingray, balloons, etc.). Because of this, it is frequently advantageous to once again ignore the existing cap and utilize Scratch and Go, and BASE to make a new and more proximal entry. As noted above, this requires a commitment to using ADR (with the aforementioned anatomical requirements). However, moving equipment through the subintimal space is often much easier than advancing through a very resistant cap.
Again, if these techniques are unsuccessful, or cannot be applied because of anatomical constraints, then a retrograde approach is necessary. A retrograde wire (knuckled) is also an effective way of modifying the proximal cap and allowing for subsequent antegrade wire and catheter advancement for retrograde dissection reentry.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
