Table 1. Overcoming BU CTO.

• Augmented guide catheter support
	Larger guide catheter with more supportive shape
	Long arterial sheaths
	Deep engagement
	Guide catheter extension
	Anchor wire
	Buddy wire
	Anchor balloon: side branch, distal target vessel or subintimal at or below lesion site
• Lesion modification
	Appropriate small balloon (1.20–1.5 mm) manipulation
	Wedgies & grenadoplasty (Intentional balloon rupture)
	Microcatheters: Tornus, Corsiar, Carvel, Finecross, Turnpike
	Excimer laser: ablative and acoustic energy
	Rotational atherectomy
	Seesaw balloon-wire cutting technique
	Multi-wire plaque crushing technique
	Crowbar effect
	Retrograde approach

BU = balloon-uncrossable; CTO = chronic total occlusion.