CT guided CTO Interention

Computed tomography angiography for guidance of the reverse CART of heavily calcified and exceptionally tortuous chronically occluded right coronary artery

Learning objective: To understand the role of coronary computed tomography angiography for guidance of reverse controlled antegrade and retrograde tracking in chronic total occlusion percutaneous coronary intervention.

65-year-old male with CCS class III angina, arterial hypertension and hypercholesterolemia was referred for the second attempt of percutaneous coronary intervention (PCI) of the chronically occluded right coronary artery (RCA). Coronary computed tomography angiography (coronary CTA) was performed for planning and peri-procedural guidance of percutaneous recanalization of RCA. Based on the high complexity of the chronic total occlusion (CTO) of the RCA on coronary CTA (blunt proximal cap, heavy calcification, severe tortuosity, long duration of CTO, previously failed attempt adding up to CT-RECTOR score of 4 points) (Figures 1 and 2), the antegrade dissection and re-entry (ADR) and reverse controlled antegrade and retrograde tracking (reverse CART) were chosen as the primary and secondary CTO PCI strategies, respectively. Following intubation of RCA with a 8F AL 0.75 guiding catheter, the intentional antegrade dissection was initiated using a 2.5x12 mm balloon assisted subintimal entry (BASE) technique and a Fielder XT-A (Asahi Intecc, Japan) knuckle wire supported by Turnpike Spiral 135 cm (Teleflex Inc, Wayne, PA, USA) microcatheter (Movie 1). The advancement of the knuckle wire was strictly navigated based on three-dimensional, color- coded CT reconstructions of the RCA (Movies 2 to 5), that were automatically aligned to the fluoroscopic angulations of the C-arm and projected onto separate monitor using a dedicated software tool (syngo CTO Guidance, Siemens Healthineers, Germany). Specifically, the working fluoroscopic angulations were selected according to CTA projections with least foreshortening of the proximal and mid RCA (Figure 1; LAO projection), and greatest delineation of the uptake of the right ventricular (RV) branch relative to the course of the main vessel (Figure 2; RAO projection). After failed attempt of ADR, the septal collateral was crossed with a Sion Black (Asahi Intecc, Japan) guidewire and followed by a Mamba Flex 150 cm (Boston Scientific, Natick, MA, USA) microcatheter (Movies 6 and 7). Subsequently, the Sion Black was exchanged for Fielder XT-A, and the retrograde knuckle was propagated to the mid portion of the RCA under CTA guidance. Particularly, the display of CTA images with clear separation of the origin of RV branch relative to the course of the RCA main vessel, prevented unintentional movement of the Mamba Flex 150 cm microcatheter after accidental advancement of the Gladius (Asahi Intecc, Japan) guidewire into the RV branch (Movie 8). Subsequently, after redirection of the guidewire towards proximal RCA, the reverse CART was finalized by successful re-entry of the Gladius guidewire into the guiding catheter (Movie 9). Ultimately, 4 drug-eluting stents (Resolute Integrity 3.0x30 mm, Resolute Integrity 3.5x38 mm, Resolute Integrity 4.0x26 mm and Resolute Onyx 5.0x18 mm) were implanted and post-dilated using 4.0 to 5.0 mm diameter non-compliant balloons according to intravascular ultrasound resulting in a satisfactory angiographic result (Movie 10). The patient remained angina-free at 3-months follow-up.

Figure 1. Three-dimensional, color-coded CTA reconstruction of RCA CTO in LAO projection displaying the exact trajectory, tortuosity and calcification of occluded RCA. Note that the red and green colors represent the coronary segments with and without foreshortening, respectively.

Figure 2. Three-dimensional, color-coded CTA reconstruction of RCA CTO in RAO projection displaying the exact trajectory, tortuosity and calcification of occluded RCA as well as the origin and course of RV branch.

Movie 1. Intentional antegrade dissection using a 2.5x12 mm semi-compliant balloon assisted subintimal entry (BASE) technique and a knuckle wire (Fielder XT-A) supported by Turnpike Spiral microcatheter (LAO projection). Note that the LAO 30 projection was selected based on the virtual C-arm in coronary CTA.

Movie 2. Further advancement of the knuckle wire along the second curvature of RCA CTO (LAO projection).

Movie 3. Verification of the antegrade knuckle relative to RV branch in RAO projection. Note that the RAO 39 projection was selected based on the virtual C-arm in coronary CTA.

Movie 4. Further advancement of the knuckle wire along the third curvature of RCA CTO (LAO projection).

Movie 5. Verification of the antegrade knuckle relative to distal CTO segment (LAO projection).

Movie 6. Angiography of the donor artery for visualization of the septal collaterals supplying distal posterior descending coronary artery.

Movie 7. Confirmation of successful septal crossing into distal posterior descending coronary artery of the RCA (RAO projection).

Movie 8. Inadvertent advancement of the retrograde knuckle into RV branch with its immediate retrieval and successful redirection towards proximal RCA based on corresponding CTA images (RAO projection).

Movie 9. Successful re-entry of the knuckle wire into the guiding catheter under CTA guidance(LAO projection).

Movie 10. Final angiographic result with restoration of antegrade coronary flow (LAO projection).

Key learning points:

1. Coronary CTA can be applied for planning and periprocedural guidance of CTO PCI.
2. The projection of 3-dimensional CTA to the catheterization laboratory with automatic alignment of CTA reconstructions and fluoroscopic images during CTO PCI allows for: 1) selection of the most optimal fluoroscopic angulations with least foreshortening and clear delineation of CTO vessel course relative to its side branches; 2) visualization of CTO tortuosity as well as the severity and extent of CTO calcification.
3. CTA-assisted CTO PCI can be particularly useful for navigation of the knuckle wire during reverse controlled antegrade and retrograde tracking, with a potential for lower risk of coronary perforations.