Case Presentation and Description of Technique
A 63-year-old gentleman underwent diagnostic cardiac catheterization at an outside hospital for acute coronary syndrome. He was found to have an eccentric, 95% right coronary AOL with preserved left ventricular function (Figure 1). Subsequently, the patient was transferred to our institution for PCI. Due to the vessel's slightly superior ostial orientation, we chose a Judkins Right 3.5 side-hole catheter. Traditionally, we have routinely employed side-hole catheters for PCI of AOL. Prior to insertion, the catheter was preloaded with 2 wires. The first wire (vessel wire) was shaped using standard technique according to the coronary curvature. An exaggerated, large loop was formed on the tip of the second wire (float wire).

Once the catheter was inserted, even transient minimal ostial engagement resulted in significant dampening of the pressure waveform and ST-segment elevation, despite the presence of side holes. The vessel wire was easily advanced into the distal artery; and the catheter was then carefully withdrawn to disengage the tip, while constantly maintaining distal wire position. Next, the float wire was advanced into the aortic root, where it remains floating (Figure 2). The catheter was then advanced over the vessel wire, with constant forward pressure against the shaft of the float wire to maintain alignment adjacent to the ostium. The float wire shaft prevented actual catheter engagement. A roadmap cineangiogram was then performed (Figure 3). With continued forward pressure on the guide catheter, a 3.5 x 8 mm Express stent (Boston Scientific, Natick, MA) was easily advanced into the lesion and directly deployed without predilatation. The proximal stent marker was placed just beyond the catheter tip, which landmarked the coronary ostium. An excellent final result was achieved (Figure 4).

Discussion
We have used this simple technique on many cases of AOL with consistent success. All but 2 have been in the right coronary system. The remaining cases were performed in the left circumflex system in a patient with separate left coronary ostia, as well as a protected left main ostial stenosis in another patient. Although this technique is aimed at intentional guide catheter disengagement, we have chosen to use side-hole catheters to minimize the pressure dampening and flow limitations during the initial vessel wire advancement phase. The choice of vessel wire is based upon operator assessment of the vessel anatomy without consideration of the AOL, while any wire can be easily shaped into the exaggerated loop for the float wire.

One popular method for approaching such lesions is to engage the catheter and to advance the proximal stent marker just beyond the tip. The entire system is then carefully withdrawn as a unit, with frequent contrast injections to define the true ostium for deployment. This technique is practical only when the stenotic lumen is large enough to allow perfusion around the catheter tip. As seen in our case, there were pressure waveform dampening and electocardiographic changes even with brief engagement of a side-hole catheter. If prolonged engagement for the entire case were required, the patient would likely have experienced significant angina and possibly clinical instability. Additionally, as stated previously, such engagement in a friable AOL can result in ostial, possibly spiral, dissection with potentially dire consequences. When using a single wire, true peri-ostial catheter positioning may be difficult. Frequently, as it approaches the ostium, the tip will be sucked in. Potential trauma can result from such repeated engagement and disengagement.

Another proposed technique for PCI in AOL involves a different dual-wire technique. Chetcuti and coauthors reported a case of re-intervention of a right coronary ostial stent with proximal protrusion into the aortic root. Catheter alignment and engagement were possible only after advancement of a wire into the inferior proximal strut of the previous stent to lever and guide the catheter tip into the stent. A second wire was then advanced into the distal vessel and successful PCI was performed.4

Another case of PCI for ostial in-stent restenosis involved not only protrusion but also likely deformation of the proximal intra-aortic struts. The authors placed the catheter tip above the stent and wired through the superior stent struts into the vessel. After dilatations were performed with serially larger balloons, a new stent was then advanced sideways through the dilated struts and deployed inside the initial stent. The proximal deformed struts were deflected inferiorly, and guide catheter engagement was then possible through this new stretched strut opening.5 As both of the above cases represented protruding previous stent struts, our technique would likely not have been applicable.

Katoh et al described insertion of a second wire through the proximal strut of the undeployed stent. This wire remains in the aortic root, thus preventing the proximal stent edge from advancing beyond the ostium.6 Although it employs a similar float mechanism to our technique, the former is likely somewhat more labor-intensive. Moreover, while not reported, there may be potential for disruption of the stent crimping onto the balloon, predisposing to dislodgement through calcified lesions.

In summary, we propose a simple PCI technique for treatment of AOL. Most have been performed in the right coronary system, as we have not previously performed unprotected left main PCI. However, as this procedure becomes more widespread, our method can potentially be quite useful for treatment of ostial left main stenoses. This anatomic subset would be at the highest morbidity and mortality risk for catheter-induced trauma. Additionally, application to non-coronary AOL, such as ostial renal artery stenoses, are also possible.

Dr. Chen can be contacted at chenjackapollo (at) yahoo. com