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A 60-year-old hypertensive male patient presented with CCS 3 angina for the last 3 months. He had an inferior wall myocardial infarction 4 months back, which was not thrombolyzed due to late presentation and managed conservatively. Physical examination was unremarkable.

Blood reports showed hemoglobin 13.6 gm/dl, creatinine 0.9 mg/dl, FBS 92 mg/dl, LDL 110 mg/dl.ECG showed Q waves in inferior leads.Echocardiography showed inferior wall hypokinesia with preserved ejection fraction of 55% and good RV function.

Coronary angiogram revealed:Normal left systemRight Coronary Artery was dominant. There was a long segment CTO from proximal part, with distal refilling of the vessel through septal collaterals from LAD.

At first the RCA CTO was attempted antegrade. After repeated use of different available wires, the lesion could not be crossed. In view of presence of adequate septal collaterals, a plan for retrograde approach was made.The RCA was cannulated with JR 3.5 6F [Medtronic], and LAD with EBU 3.5 7F [Medtronic]. With the help of Caravel microcatheter [Asahi Intecc], a Runthrough NS Extra-floppy wire  [Terumo] was exchanged with a Sion Blue [Asahi Intecc] for entering the septal collateral. Selective contrast injection through the Caravel was done to delineate the collateral channel and exclude wire-induced perforation. After wire entered the distal RCA, the Caravel could be negotiated into the distal RCA. Then the Sion blue was exchanged with a Fielder XTR [Asahi Intecc] in an attempt to cross the lesion. It was escalated to Runthrough NS Intermediate wire [Terumo]after the lesion could not be crossed with Fielder XTR. After successful crossing, the Caravel was also negotiated proximal to the lesion, and the wire and Caravel were passed inside the JR guide-catheter. Intermediate wire was then exchanged with RG3 wire [Asahi] for externalization. Then, antegrade pre-dilation with 2 X 10mm semi-compliant Tazuna Balloon, and stenting of RCA with 3.5 X 38mm Promus Element Plus [Boston] at 14 atmospheres was performed. Post dilation with 3.5 X 15 mm NC balloon yielded a satisfactory angiographic outcome.Procedure was uneventful.

Antegrade approach, though preferred in most CTO interventions, is not always successful. Retrograde approach is a good alternative in those cases. Appropriate collateral selection is the key to success. Comprehensive knowledge of all instruments and wires is essential for a favorable outcome.