If at First You Don’t Succeed, Try, Try Again: A Stepwise Approach to the Non-Dilatable Lesion

An ongoing challenge in interventional cardiology is the approach to the resistant coronary lesion that is non-dilatable using conventional balloon angioplasty. The ultimate success of the angioplasty procedure may hinge on having a defined series of maneuvers to attempt before admitting defeat. Numerous techniques have been described for approaching non-dilatable lesions, including conventional balloon techniques, longitudinal force-focused angioplasty, cutting balloons, and rotational and laser atherectomy systems for lesion debulking and modification. We describe a case using an escalating, stepwise approach to a non-dilatable lesion, which ultimately was successfully dilated after the use of an excimer laser catheter.

Case report
A 60-year-old male with a history of diabetes mellitus on oral hypoglycemic agents, hyperlipidemia, and known coronary artery disease presented with recurrent angina nearly 12 years after coronary artery bypass surgery. A stress test demonstrated anterolateral ischemia, after which the patient underwent cardiac catheterization at an outside hospital. The saphenous vein bypass graft to the second diagonal branch contained a high-grade proximal stenosis felt to be the culprit lesion. Percutaneous coronary intervention of this vein graft lesion was performed with placement of bare metal stents due to concerns about gastrointestinal bleeding at the time.

Six months after this vein graft stent procedure, the patient developed recurrent unstable anginal symptoms despite an optimized anti-anginal regimen, which prompted repeat cardiac catheterization at our institution. The vein graft to the second diagonal branch was now 100% occluded proximally within the previously placed stents (Video 1). The native second diagonal branch contained a tubular, non-calcified 99% stenosis in the proximal third of the vessel (Figure 1, Videos 2 and 3). Rather than re-intervene on the 12-year-old vein graft, which was now totally occluded, a decision was made to intervene on the subtotally occluded native diagonal branch.

A 6 French XB 3.5 (Cordis) guiding catheter was used to engage the left coronary artery and anticoagulation was achieved using intravenous bivalirudin. A Runthrough NS (Terumo) guide wire was used to cross the lesion. An Emerge (Boston Scientific) 2.25mm x 15mm compliant balloon was inflated multiple times. Despite inflation pressure up to 16 atmospheres, significant waisting of the balloon persisted (Figure 2, Video 4) without significant angiographic improvement in lesion appearance (Figure 3). Subsequently, an NC Quantum Apex (Boston Scientific) 2.0mm x 15mm non-compliant balloon was used to perform a prolonged high-pressure inflation. Despite an inflation pressure of 24 atmospheres, significant waisting was still observed (Figure 4, Video 5). There was no significant improvement in the lesion. An Asahi Prowater (Abbott Vascular) guide wire was then placed as a parallel buddy wire and focused force balloon angioplasty was performed (Figure 5, Video 6), but again without successful dilatation of the lesion. A 2.0mm x 10mm AngioSculpt scoring balloon (Spectranetics) was then attempted, but was unable to cross the lesion. Repeat angiography following these maneuvers demonstrated significantly impaired coronary flow (Figure 6, Video 7). Due to unsuccessful lesion dilatation using the multiple balloons and techniques described above, excimer laser debulking of the lesion was performed using a 0.9mm ELCA X-80 laser catheter (Spectranetics) (Figure 7, Video 8). After two passes with the laser catheter, an NC Quantum Apex 2.0mm x 12mm non-compliant balloon was then able to successfully dilate the lesion, with the residual waist yielding at less than 12 atmospheres of pressure (Figures 8 and 9, Videos 9 and 10). Following this, the lesion was treated with tandem Promus Premier (Boston Scientific) drug-eluting stents (2.25mm x 24mm and 2.25mm x 8mm). Final post dilatation of the stents was performed using a NC Trek (Abbott Vascular) 2.5mm x 15mm balloon at 18 atmospheres. Excellent angiographic result after intervention was noted with no residual stenosis (Figure 10, Videos 11 and 12).

The patient had an uncomplicated post-procedural course and has remained angina free after the intervention. He continues on dual antiplatelet therapy with aspirin 81mg and clopidogrel 75mg daily. 

Discussion

Lesion dilation during balloon angioplasty is a complex process involving plaque fracture, compression, and stretch.¹ This case study demonstrates the sequence of a stepwise approach to a challenging non-dilatable lesion (Table 1). After the lesion failed to dilate following repeated inflations with a workhorse compliant balloon, the next procedural step taken was to perform high-pressure inflations using a noncompliant balloon. Despite inflation pressures up to 24 atmospheres, the lesion remained recalcitrant and non-dilatable. Another option that could have been considered at this point would have been to deploy a slightly larger-sized balloon, as dilating force is proportional to the inflated balloon diameter.² However, we would caution against using balloons whose inflated size would be larger than the reference vessel diameter. Oversized balloons inflated at high pressure would be more likely to lead to serious untoward complications such as coronary dissection and perforation. 

Subsequent strategies attempted to achieve lesion dilation with plaque scoring techniques. The first strategy was to place a parallel buddy wire outside the noncompliant balloon to perform longitudinal focused force angioplasty, a technique that has been utilized successfully in resistant and calcified lesions.^3,4 The parallel external wire is intended to focus the dilating pressure. Theoretically, by focusing the force of balloon dilatation, greater longitudinal- and radial-directed stress is exerted on the lesion, as opposed to circumferential shear stress, which can create dissections in multiple, random planes. The same principle of action is the basis of the atherotomy balloon catheters (Cutting Balloon and AngioSculpt balloon). The Cutting Balloon (Boston Scientific) is designed with 3 or 4 microtome blades attached to the balloon in order to score the plaque during balloon inflation. Depending on balloon size, the cutting force at the blade edges is estimated to be augmented 200,000- to 400,000-fold. Bertrand and colleagues described the successful use of the Cutting Balloon in six patients with lesions that were resistant to dilation with conventional balloons.⁵ With a similar mechanism of action, but different design than the Cutting Balloon, the AngioSculpt Scoring Balloon Catheter (Spectranetics) is comprised of spiraling nitinol filaments as scoring elements that encircle a semi-compliant nylon balloon.⁶ A drawback of these scoring balloons is that their larger profiles and metallic scoring elements make them bulkier and more difficult to deliver across tight stenoses. This was observed in our patient, where even the smallest 2.0mm AngioSculpt device failed to cross the lesion. Another potential limitation of cutting and scoring balloons is the need for a guiding catheter ≥6 French. Accordingly, if a non-dilatable lesion is encountered during a procedure with a 5 French guide (as is increasingly used with radial artery interventions), focused force angioplasty with a buddy wire would be an alternative option prior to upsizing the sheath and guide catheter.⁷

When lesions cannot be dilated by balloon angioplasty, plaque modification and debulking with atherectomy devices becomes the default option. While atherectomy techniques have largely failed to have a significant impact on restenosis post-percutaneous coronary intervention (PCI), the non-dilatable lesion represents an important niche application for these devices.⁸ Options include rotational atherectomy, orbital atherectomy, and excimer laser atherectomy. Rotational and orbital atherectomy are especially useful in treating highly calcified lesions. Rotational atherectomy has been shown to be successful in approximately 90% of lesions that are either undilatable or uncrossable with balloons.⁹ Of the various atherectomy devices, rotational atherectomy is the most widely available option, as many hospitals do not have the alternative devices, especially the excimer laser, which carries more expensive capital outlays. Orbital atherectomy, recently approved for heavily calcified lesions, is designed to create plaque modification prior to balloon dilation and stent placement. To our knowledge, use of this device to treat a non-dilatable lesion after an attempted but unsuccessful balloon angioplasty has not been reported. A note of caution should be sounded for non-dilatable lesions where a significant intimal dissection has been created by aggressive or high-pressure balloon inflations. Rotational and orbital atherectomy are contraindicated in this setting, because of potential traumatic complications from the burrs ablating in the subintimal space and propagating the dissection. 

The atherectomy device used to successfully treat the balloon-resistant lesion in our patient was the excimer laser. Of the various atherectomy devices, the excimer laser is unique in having an approved indication for “lesions which previously failed balloon angioplasty.” A subgroup analysis of the Percutaneous Excimer Laser Coronary Angioplasty registry assessed the use of the excimer laser in 37 patients with non-dilatable lesions.¹⁰ Clinical success, defined as a post-procedural residual stenosis <50% with no major in-hospital complication, was achieved in 33 of 37 patients (89%). The catheter used in our case was the ELCA X-80 (Spectranetics), a xenon-chlorine pulsed laser that delivers a high energy density output with low heat production. The catheter is 0.9mm in diameter and is comprised of 65 concentric 50µm fibers. The catheter delivers energy (wavelength 308nm, pulse length 185ns) from 30 to 80mJ/mm² at pulse repetition rates from 25 to 80 hertz, using lasing power cycles of 5 seconds on/10 seconds off. Use of the ELCA X-80 laser catheter was prospectively studied in 100 patients with complex, severe lesions (defined as the presence of calcification, chronic total occlusion, or uncrossable with balloon catheters).¹¹ Procedural success was achieved in 93% and clinical success in 86%. Since this device is compatible with 6 French guiding catheters and is delivered over conventional .014-inch guide wires, it is well suited for ad hoc use to treat non-dilatable lesions, as in our patient.

In conclusion, the recalcitrant non-dilatable lesion poses a frustrating clinical challenge. Having a stepwise strategy can be helpful to safely and successfully snatch victory from the jaws of defeat. 

Acknowledgement. We thank Roseanne McGettigan and Marguerite Davis for their assistance in preparing the illustrations. 

This article received a double-blind peer review from members of the CLD Editorial Board.

Disclosures: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Michael P. Savage, MD, at michael.savage@jefferson.edu.

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