Distal Side Branch Entry Technique to Accomplish Recanalizationof a Complex and Heavily Calcified Chronic Total Occlusion

Percutaneous intervention of chronic total occlusions (CTOs) can improve exercise capacity, symptoms and left ventricular function.¹ The parallel wire technique is a useful technique in recanalizing CTOs.² This technique utilizes a second wire to cross into the true lumen, while leaving the initial wire in a dissection plane or false lumen.² The initial wire is used as a guide for where not to cross, and also may act to occlude the entry point to the false lumen, thereby improving chances of true luminal wiring. The bilateral/contralateral injection technique has been described to visualize and guide distal luminal wire placement through a CTO.³ Well developed collaterals often provide flow from a contralateral vessel to the distal portion of the occluded artery.⁴ These collaterals help to maintain myocardial viability and prevent myocardial ischemia at rest, however, they provide flow equivalent to a 90–95% antegrade stenosis.⁴

Coronary dissection planes often tend to end at vessel bifurcations. Anecdotally, distal side branch entry of a wire is utilized to prove luminal entry post coronary dissection wiring. Side branch entry has previously not been described to confirm luminal wiring when crossing CTOs after the creation of multiple dissection planes. We describe the combined use of the side branch entry technique, contralateral injection method, and the parallel wire technique to accomplish successful stenting of a complex, calcified, long and blunt chronic occlusion with bridging collaterals.

Case Report. A 67-year-old male presented 1 year ago with acute coronary syndrome and a 90% mid-right coronary artery (RCA) stenosis. His coronary risk factors included diabetes, hypertension, hyperlipidemia and obesity. Due to a concomitant gastrointestinal bleed, percutaneous intervention was not performed at the time. Medical management was carried out with success initially. Due to recurrent Canadian Cardiovascular Society Class II–III angina over the previous 4–5 months, an outpatient stress test was performed. At an exercise level of 4 METS, the patient experienced angina, diffuse ST-depression and ischemic polymorphic ventricular tachycardia. He was admitted to the hospital and invasive angiography was performed. The left coronary system had diffuse mild-to-moderate disease, which was unchanged from the previous year. The large, dominant RCA was now occluded in its proximal segment with a blunt entry point and bridging collaterals supplying TIMI 1 (Thrombolysis In Myocardial Infarction) distal flow (Figure 1). The occluded segment was heavily calcified and well over 25 mm in length. After a discussion about the risks and benefits, the patient was brought back to the laboratory the next day for percutaneous intervention.

The RCA ostium was engaged with an AL2, 6 Fr guiding catheter. A clopidogrel loading dose was administered the night before the procedure. Heparin alone was used as anticoagulation. A Wizdom wire (Cordis Corp., Miami Lakes, Florida) with balloon backup (1.5 x 15 mm rapid exchange balloon) wasattempted first. This wire, however, passed into an extraluminal dissection plane (Figure 2). Next, a Cross-it-200 wire once again passed into a larger and more distal dissection plane (Figure 3). This wire was left in place and a stiff Asahi Miracle Brothers 6 g 0.014 inch wire (Abbott Vascular Inc., Abbot Park, Illinois) was passed in a parallel fashion. This second wire appeared to take a different course toward the outer curvature of the vessel, crossing over the first wire (Figure 4). There was, however, resistance felt when trying to maneuver the wire forward. The presence of a large, acute marginal/right ventricular branch at the distal end of the occluded segment was noted from antegrade and contralateral injections. Rather than push the wire forward, risking extension of a third dissection plane, it was felt that if the side branch could be wired, luminal entry would be more likely. The Miracle 6 g wire was then carefully maneuvered into the acute marginal vessel with some difficulty (Figure 5).

There was no evidence of contrast extravasation or extrasystoles to indicate pericardial entry or wire perforation. At this point, a JL4 diagnostic catheter was engaged in the left main ostium via the left femoral artery. Contralateral injection demonstrated true acute marginal entry. Next, utilizing contra-lateral injections, the same wire was successfully maneuvered into the main vessel (Figure 6). Subsequent balloon inflations with 1.5 x 15 mm and 2.5 x 15 mm balloons restored TIMI 3 antegrade flow. A glycoprotein IIb/IIIa inhibitor was initiated at this point. Due to the length of the stenosis, overlapping 3.0 x 33 mm and 3.5 x 13 mm sirolimus-eluting stents were deployed at high pressure. Both stents were postdilated with a3.75 x 20 mm noncompliant balloon at 20–22 atm. An optimal angiographic result was obtained with brisk TIMI 3 flow (Figure 7).
Collaterals were now seen opacifying the apical left anterior descending artery upon right coronary injections, demonstrating brisk flow. A month later, the patient was able to exercise for over 9 METS with no angina, no ST-segment change and no ventricular tachycardia.

Discussion. Several factors predict failure to cross a CTO with a wire. These include complete occlusions versus functional occlusions, duration of occlusion > 3 months, length of occlusion > 15 mm, presence of a blunt versus tapered stump, side-branch at entry point, presence of intracoronary bridging collaterals, lesion calcification and RCA or circumflex occlusion.⁵
Initial wires often enter into dissection planes within calcified, long occlusions. Dedicated CTO wires have improved the success rate for CTO intervention. One set of these include the Asahi family of Miracle Brothers 3–12 g wires. These are nonhydrophilic stiff wires with a long radio-opaque segment. They have excellent torque control and good support at the expense of some flexibility.
This occlusion had several unfavorable characteristics including a blunt entry point, the presence of bridging collaterals, patient symptoms indicating occlusion duration over 3 months, long occlusion length (> 25 mm) and heavy calcification. These factors decrease procedural success and increase complication rates.
There are thus three techniques to recanalize a complex, long, heavily calcified CTO. First, the parallel wire technique is successful in guiding the third wire into the presumed true lumen. Next, the side branch entry technique is a useful method to confirm luminal entry distal to the occlusion site. This technique assumes that dissection planes often end at side branches, which would in turn imply that entry into a side branch likely confirms true luminal wire entry. Lastly, the contralateral injection technique can be used to guide further wire manipulation into the distal vessel. This method requires the presence of sufficient collaterals to adequately opacify the occluded vessel.
Other techniques which can be utilized to confirm luminal distal wire placement include injection of contrast distally through an over-the-wire balloon or a transport catheter. Intravascular ultrasound (IVUS) can also confirm luminal entry versus entry into a dissection plane. The above methods, however, risk extension of a potential dissection plane with distal contrast injection or the passage of an IVUS catheter.
Our method of side branch entry reduces the above risk, while offering a reasonably specific method of confirming true luminal entry. This case also outlines the importance of combining multiple techniques (parallel wire, contralateral injection and our side branch entry technique), when trying to recanalize complex CTOs. Ultimately, perseverance and careful wiring in multiple orthogonal views remains the cornerstone of successful CTO recanalization.

References

1. Puma JA, Sketch MH, Tcheng JE, et al. Percutaneous revascularization of chronic coronary occlusions: An overview. J Am Coll Cardiol 1995;26:1–11.

2. Ochiai M, Ashida K, Arki H, et al. The latest wire technique for chronic total occlusion. Ital Heart J 2005;6:489–493.

3. Singh M, Bell MR, Berger PB, Holmes DR Jr. Utility of bilateral coronary injections during complex coronary angioplasty. J Invasive Cardiol 1999;11:70–74.

4. Flameng W, Schwarz F, Hehrlein FW. Intraoperative evaluation of the functional significance of coronary collateral vessels in patients with coronary artery disease. Am J Cardiol 1978;42:187–192.

5. Safian RD, Freed MS. The Manual of Interventional Cardiology, 3rd edition. Birmingham: Physicians’ Press. 2002; pp. 288–291.