Contrast modulation in chronic total occlusion percutaneous coronary intervention

Abstract

The intraplaque injection of contrast media in the recanalization of coronary chronic total occlusions (CTO) has witnessed a dynamic journey since its initial formulation. Contrast‐guided subintimal tracking and re‐entry (STAR) was the first contrast modulation technique for CTO percutaneous coronary intervention (PCI). With this technique, a forceful injection of a large volume of contrast (3–4 mL) was performed in order to achieve hydraulic recanalization of the vessel. This approach was associated with extensive vessel injury and unpredictable true lumen re‐entry, which were in turn linked to high rates of restenosis on follow‐up. In the subsequent iteration, called the “microchannel technique”, a smaller amount of contrast media (1 mL) was gently injected inside the plaque to modify its compliance by softening and recruiting loose tissue, which facilitated subsequent true‐to‐true lumen crossing with a polymer‐jacketed wire along paths of least resistance. The microchannel technique has later evolved into what is currently known as the “Carlino technique”, where a minimal volume of contrast media (<0.5 mL) is gently injected inside the occlusion, with the goal of modifying plaque compliance to facilitate guidewire and microcatheter advancement through a fibrocalcific plaque. The Carlino technique is now widely utilized to allow negotiation of difficult‐to‐cross occlusions, particularly by the “hybrid operators”, with high success rates and low incidence of complications. The purpose of this article is to provide a historical perspective on the use of contrast modulation in CTO PCI, its pathophysiological basis, as well as technical recommendations on how and when to perform these maneuvers.

Role of the retrograde Carlino technique for chronic total occlusion percutaneous coronary intervention

“…There have been some misconceptions about the Carlino technique, which is considered by some operators an exclusively subintimal or extraplaque facilitating technique. 6,8 While this classification correctly applies for the extraplaque application of the technique (see Section 2), it must be underscored that if the microcatheter is located intraplaque (intraplaque application), plaque modification will take place, possibly favoring a retrograde wiring approach ("true-to-true" recanalization). In fact, one quarter of successful cases in our series were recanalized with such a crossing strategy.…”

“…The Carlino technique has been previously described in detail. 6,8 Briefly, a small (<0.5 ml) volume of contrast is gently injected through a microcatheter advanced into the occlusion. In case of intraplaque location of the microcatheter (intraplaque application; Figure 1), contrast injection will distribute along loose tissue planes within the occlusion and will modify plaque compliance by softening it, with the goal of making subsequent gear advancement easier.…”

Use of the Limited Antegrade Subintimal Tracking Technique in Chronic Total Occlusion Percutaneous Coronary Intervention

“…into what is currently known as the "Carlino technique" in which a minimal volume of contrast (<0.5 mL) is gently injected inside the occlusion, with the goal of modifying plaque compliance to facilitate guidewire and microcatheter advancement through fibrocalcific plaque. 16 Another variation of the STAR technique was the "mini-STAR" in which a soft, polymer-jacketed wire is used to achieve a more proximal wire re-entry after the occlusion. Compared with the initial STAR technique, newer guidewires such as Fielder XT (Asahi Intecc) were used in mini-STAR; however, the acute and long-term results were similar with the original STAR, with high rates of restenosis/reocclusion.…”

The “Direct tip injection in occlusive lesions (DIOL)” fashion

“…The DIOL is a procedure which can be performed from antegrade and/or retrograde approach and feature with creating dissections by hydraulic pressure. Contrast-guided subintimal tracking and re-entry (STAR), microchannel technique, and Carlino technique have already been developed as the contrast modulation techniques for difficult-to-cross CTOs in the coronary field (Azzalini et al, 2019 ). However, the vascular pathology and lesion characteristics in patients with coronary artery disease are different from that in PAD patients.…”