When to Do and How to Do Conventional Reverse CART and Directed Reverse CART?

A 55 years old male was admitted for NSTEMI. Echocardiogram showed impaired left ventricular systolic function with hypokinesia over the inferior wall. Wall thickness was preserved. He has a history of hypertension, and NSTEMI with PCI done to the LCX in 2012.

Coronary angiogram showed minor disease over the LAD artery. The old stent over the pLCx remained patent. pRCA lesion was calcified with a long CTO lesion (Movie 1). It was followed by diffuse mRCA disease and another totally occluded lesion over the dRCA. Therefore, the RCA had double CTO lesions. After discussing with the patient and reviewing the echocardiogram findings, he agreed to undergo PCI.

Careful anatomical analysis is always the most important initial step for CTO intervention.

Proximal Cap Analysis
(Figure 1) The proximal cap was ambiguous. Two big side branches were located immediately in the front of the proximal cap. The proximal lesion was calcified but it showed the contour of the vessel.

Distal Cap Analysis
The distal cap ended before the bifurcation of PLV branch and PDA. Bridging collaterals were noted over the distal RCA (Figure 2).

Interventional septal was present (Movie 2).

Procedure
Antegrade preparation: The proximal cap was punctured by Conquest Pro 12 followed by step-down approach using Gaia 3rd wire (Figure 3). Further advancement was difficult because of heavy calcification.

Retrograde approach: Sion wire was chosen to cross the 1st septal, supported by Turnpike LP 150cm. After crossing the channel, the Sion wire was replaced with Fiedler XTR/A while trying to pass through the microchannel of distal RCA CTO lesion. The wire was then stepped up to pilot 200 and it was advanced to mid RCA. Hydrophilic wire was the choice in this situation because of unclear path. However, advancement of the retrograde Turnpike LP was difficult because of calcified lesion.

How to tackle the impenetrable distal cap?
The pilot 200 was not able to penetrate the distal cap of proximal RCA CTO lesion without good support of Turnpike LP. After careful wire manipulation, knuckle wiring technique was used to remove the ambiguity. The wire was then passed from the true lumen into the softer subintimal space (Figure 4).

Preparation of Reverse Control Antegrade Retrograde Tracking (xCART)
Antegrade wire was stepped up to pilot 200. It was further advanced into the mRCA. Retrograde wire was changed to Gaia 2nd for preparation of conventional reversal cart technique. There are four scenarios of reverse CART to describe the relationship of antegrade wire, retrograde wire, true lumen and false lumen (Figure 5). We need different kinds of technique to handle each scenario of reverse CART. IVUS was definitely helpful. However, it was not possible to advance it because the pRCA was heavily calcified. A technique called balloon assisted micro-dissection (BAM) was used. A 1.5 mm semi-compliant balloon was inflated until it burst. It could change the compliance of the lesion and fascinate the passage of other devices.

Attempt of conventional reverse CART
After that, a 2.0 mm semi-compliant balloon was advanced. The antegrade wire should be in true lumen and the retrograde wire should be in the false lumen. A bigger size balloon should be used to create dissection planes for the retrograde wire re-entry. The retrograde wire should be pointed towards the side of balloon. After deflating the antegrade balloon, the retrograde wire would enter the space created by the balloon through the dissection plane. However, the proximal lesion was un-dilatable as shown (Figure 7). Conventional reverse CART was extremely difficult.

Directed reverse CART
The basis of a reverse CART operation was to move from the pRCA to the dRCA to avoid the heavily calcified portion. The antegrade wire was very likely inside the true lumen. The retrograde wire very likely remained inside the true lumen while the knuckle wiring technique was initiated (Figure 8). In this true-true antegrade and retrograde wire relationship, we should intentionally to use directed reverse CART technique. After inflating a 2.0 mm semi-compliant balloon, the controllable retrograde Gaia 2nd wire was directed towards the end of balloon instead of the side. This could increase the chance of success and minimize the length of subintimal space (Figure 9).

Final
Reverse CART was successfully done. The retrograde wire entered into the true lumen. After performing the directed reverse CART repeatedly, the retrograde wire entered into the antegrade guiding with retrograde turnpike LP afterwards. RG3 wire was then externalized. The proximal part of lesion was further dilated with Non-compliant balloon at very high pressure in order to crack the calcified lesion. The RCA lesions were further pre-dilated with semi-compliant balloon. IVUS guided stenting was done by deploying three drug-eluting stents (Movie 3).

Final angiographic result was excellent. Patient remained symptom free and his exercise tolerance improved after the procedure.

Learning points
This case illustrates how to perform reverse CART based on the relationship of antegrade and retrograde wires. Conventional reverse CART and directed reverse CART are important concepts to perform reverse CART effectively.

Acknowledge
Dr. Eugene Brian WU, Prince of Wales Hospital, Hong Kong