Chronic total occlusions - Current techniques and future directions

Abstract

Chronic total occlusions (CTOs) of coronary arteries represent a common and significant challenge to interventional cardiology. Medical therapy is often regarded as an adequate long term strategy in the management of these lesions with surgical intervention for refractory symptoms. Extensive collateralisation is used as a marker of distal coronary perfusion, further reinforcing non-invasive strategies. This together with relatively low percutaneous success rates outside of specialised centres has meant that rates of percutaneous intervention have remained low. Increasing evidence suggests that CTOs are not a benign entity. Further, symptom control and quality of life improve significantly with successful percutaneous revascularisation. Both factors have reignited interest in percutaneous modalities. The Japanese have been pioneers in the field of CTO intervention although their success rates have been difficult to replicate. New techniques and equipment developed in North America offer an alternative to the Japanese approach. These techniques focus on time, radiation and contrast minimisation. This review will assess the histopathology of CTO and shifting paradigms in CTO treatment strategies.

Keywords: Antegrade; Chronic total occlusion; CrossBoss; Knuckle wire; Retrograde; Reverse CART; Stingray balloon; Techniques.

Fig. 1

The J-CTO score is used to characterise lesion complexity in a standardised way. Reproduced with permission from Morino et al. .

Fig. 2

The J-CTO score predicts the ability to cross the lesion antegrade in less than 30 min. This underpins the algorithm and rapid shifts in strategy advocated in the hybrid approach (see below) Reproduced with permission from Morino et al. .

Fig. 3

Controlled drilling vs penetration for intimal plaque tracking.

Fig. 4

A 30 to 60 degree distal bend 1 to 2 mm from the tip should be placed on the wire for controlled drilling or penetration. Reentry into the true lumen requires a high penetration force wire with a more acute bend. Reproduced with permission from Thach N et al. Practical Handbook of Advanced Interventional Cardiology: Tips and Tricks, 4th Edition Wiley and Sons .

Fig. 5

Secondary bend 3 to 6 mm from the tip is useful if the proximal vessel is tortuous.

Fig. 6

Parallel wire technique.

Fig. 7

Seesaw wiring technique.

Fig. 8

Flush occlusion with a side branch. Entry into the CTO from the side branch can be facilitated with IVUS placed in the side branch.

Fig. 9

IVUS placed in the subintimal space can help guide reentry to the true lumen.

Fig. 10

Reverse CART technique. A. Angiographic depiction of the technique. B. A balloon is inflated over the antegrade wire within the subintimal (subluminal) space that is connected proximally to the true lumen. The retrograde wire is advanced toward the newly created space. Imaged reproduced with permission from Joyal et al. .

Fig. 11

The American methodology — “hybrid approach”. Anatomy defines the strategy , . A minimal number of wire choices are available to simplify methodology, minimise cost and allow adoption of the technique in a variety of catheter laboratory environments.

Fig. 12

CrossBoss dissection system (Boston Scientific) .

Fig. 13

The Stingray reentry system (Boston Scientific) .

Fig. 14

A knuckle is formed on the retrograde wire by first fashioning a broad curve and then advancing forward. A soft polymer jacketed wire (e.g. Fielder XT, Pilot 50) is ideal. Image reproduced with permission from Joyal et al. .