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Keywords:

  • percutaneous coronary intervention;
  • stent underexpansion;
  • laser angioplasty

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

We report the successful management of underexpansion of a newly deployed coronary stent refractory to balloon dilatations. Direct stenting was performed for a lesion in the mid left anterior descending artery (without angiographically apparent heavy coronary calcification). The stent remained underexpanded despite repeated balloon dilatations including with high-pressure inflations. Subsequently, an excimer laser catheter was used in an attempt to vaporize the plaque by the accoustomechanical effect of the rapidly exploding bubbles. The overall angiographic result was good after further balloon dilatation with ordinary pressure and full stent expansion was achieved. Management of underexpansion of a newly deployed stent is a potential indication of laser angioplasty. © 2013 Wiley Periodicals, Inc.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

Management of refractory underexpansion of newly deployed coronary stents remains to be a technical challenge despite improvements in angioplasty techniques and presence of high-pressure balloon catheters. Of paramount importance is, no doubt, a good judgment before the procedure regarding the need for atherosclerotic plaque debulking or modification prior to stent deployment. Nevertheless, angiography alone sometimes is not sensitive enough to predict the amount of plaque present as well as the associated resistance to stent deployment.

High-energy excimer laser has been reported to be useful for various indications. We report a case of laser energy application in the management of underexpansion of a newly deployed coronary stent. The stent, which could not be fully expanded despite repeated high-pressure balloon inflations, was successfully expanded after facilitation using high-energy excimer laser.

CASE REPORT

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

We report the case of a 79-year-old hypertensive active male smoker with exertional chest pain. Coronary angiography demonstrated a 90% proximal to mid-right coronary artery (RCA) lesion, chronic total occlusion of the proximal left circumflex artery (LCx) and 90% stenosis of the left anterior descending artery (LAD) at the level of second diagonal branch (D2) ostium (Fig. 1). Percutaneous and surgical options were discussed and the patient wished to proceed with percutaneous revascularization. First, successful angioplasty with stenting was performed to the RCA.

image

Figure 1. Coronary angiography showed 90% lesion over mid portion of LAD at the level of the D2 bifurcation (arrows).

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Subsequently, elective, staged percutaneous intervention to the LAD was performed via right common femoral artery access. Using a 6Fr EBU 4.0 SH Guiding Catheter (Medtronic, Minneapolis, MN), a 0.014″ Iron Man Guidewire (Abbott Vascular, North Chicago, IL) and a 0.014″ Grand Slam Guidewire (Abbott Vascular, North Chicago, IL) were introduced into the LAD and D2, respectively. Direct stenting with a 2.5 mm × 20 mm PRO-KINETIC stent (Biotronik, Berlin, Germany) in the mid LAD was performed. However, despite multiple balloon dilatations including high-pressure balloon (2.5 mm × 20 mm OPN NC, SIS-Medical AG, Winterthur, Switzerland) inflations up to 30 atmosphere (ATM), the stent remained underexpanded (Fig. 2). A 0.9 mm ELCA Lasercatheter (Spectranetics, Colorado Springs, CO) was introduced into the LAD. The tip of the catheter was advanced slowly at about 1 mm/sec through the poorly expanded stent region while excimer laser energy was delivered. There were no difficulties advancing the Laser catheter. We started with a fluence of 60 mJ/mm and frequency of 40 Hz. A total of five sequences with the same setting were performed (5 sec “laser-on” time and 10 sec “laser-off” time for each sequence) with concomitant contrast injection during lasing instead of the standard saline flushing technique of 2–3 mL/sec. Further balloon dilatations up to 12 ATM were performed. Good stent expansion was achieved with an excellent final angiographic result (Figs. 3 and 4).

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Figure 2. Upper left: A 2.5 mm × 20 mm PRO-KINETIC Stent (arrows) was deployed; Upper right: angiography showed poor stent expansion; Lower left and lower right: poor stent expansion despite repeated high pressure balloon inflations.

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image

Figure 3. Tip of 0.9 mm ELCA Lasercatheter (Spectranetics, Colorado Springs, CO) was advanced to the underexpanded stent portion.

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image

Figure 4. Good stent expansion was achieved after laser angioplasty with further balloon dilatation.

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DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

Laser angioplasty with adjunctive balloon angioplasty has been used for more than 20 years. According to randomized controlled studies and a meta-analysis [1], it is not superior to conventional angioplasty. However, it is generally regarded as a safe and efficient technology in carefully selected patients for whom conventional angioplasty would otherwise be technically difficult or impossible [2]. It consists of a thin, flexible fiber-optic catheter connected to an external laser-generating source, with the tip of the catheter system emitting pulses of laser light to vaporize atherosclerotic plaque. It has been shown to be effective in management of in-stent restenosis [3]. Other indications include total occlusions crossable by a guidewire, long lesions, and lesions that previously failed angioplasty and occluded saphenous vein grafts [4].

In this case, full stent expansion was not achieved despite repeated and prolonged inflations with a high-pressure balloon. This was likely attributed to the bulkiness and resilience of the atherosclerotic plaque. When faced with a calcified or ostial lesion it is important to identify the need for plaque modification or debulking (e.g., with rotational atherectomy) by pre-dilatation before stenting. However, angiography occasionally underestimates the severity of coronary calcification [5]. Sometimes a non-calcified non-compliant densely fibrotic plaque may be encountered. Regardless of the underlying reason, stent underexpansion may be associated with a higher risk of in-stent restenosis and acute or subacute stent thrombosis [6]. Hence, when a stent cannot be appropriately dilated with high-pressure balloon inflation, alternative options require exploration.

One treatment option is rotational atherectomy. Its use has previously been reported [7]. However, the stent acts as a barrier between the burr and the plaque. Therefore, the plaque, which causes the inability to dilate, can only be reached by extensive rotational atherectomy that will inevitably lead to partial removal of the stent struts together with the superficial layers of the plaque. Moreover, the fate of embolization of micro-particles resulting from stent destruction is unknown. The use of a cutting balloon has been reported in the setting of stent underexpansion associated with significant in-stent restenosis 4 months after the initial procedure [8]. There likely is no utility to the use of this approach for an under-expanded newly deployed stent given the inability of the blades to reach the plaque due to the stent struts. Surgical revascularization can be considered. However, this approach would be associated with the risk of open chest surgery. Furthermore, despite stent under-expansion, the degree of flow-limitation may not be sufficient to maintain long-term graft patency. If surgery is contemplated it should be performed as soon as possible given the risk of in-stent thrombosis and pre-treatment with dual antiplatelet therapy may increase the surgical risk. High-energy excimer laser works by vaporization of refractory plaque beneath the stent struts and by the accoustomechanical effects of rapidly exploding micro-bubbles generated within the contrast media. With laser angioplasty followed by adjunctive balloon angioplasty, full stent expansion, and successful angiographic results were achieved. There was no complication. Management of refractory stent under-expansion by laser angioplasty has been reported for a newly deployed stent as a staged procedure [9] or in the context of in-stent restenosis [10].

In order to maximize the accoustomechanical effects of laser, saline flushing was not given during laser energy delivery. It is traditionally not recommended to omit saline flushing during laser energy application (according to the instructions for use), especially for de novo lesions in view of its potential in causing dissection and perforation secondary to excessive vessel injury [11]. Use of excimer laser with contrast medium without saline flushing has only been reported in the management of stent under-expansion at a delayed time frame [12]. In that particular case, the author believed that by 18 months the vessel wall would be supported and protected by the stent that would likely already have been endothelialized. To the best of our knowledge, this is the first case report of using excimer laser catheter in a contrast medium to manage a newly deployed, underexpanded stent. It was successful and without complications.

Our patient was discharged uneventfully on the following day. Lifelong aspirin and 4 weeks of clopidogrel were recommended. He remained stable and completely free of chest pain at 10 months.

LIMITATION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

Intravascular ultrasound (IVUS) was not performed during the procedure. Therefore, the degree of calcification of the underlying plaque as a cause or contributor for stent underexpansion could not be assessed.

CONCLUSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

This case demonstrated the utility of laser application to allow expansion of a newly deployed otherwise unexpandable stent.

ACKNOWLEDGMENTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES

Horst Sievert has ownership interest in or has received consulting fees, travel expenses or study honoraries from the following companies: Abbott, Access Closure, AGA, Angiomed, Arstasis, Atritech, Atrium, Avinger, Bard, Boston Scientific, Bridgepoint, Cardiac Dimensions, CardioKinetix, CardioMEMS, Coherex, Contego, CSI, EndoCross, EndoTex, Epitek, Evalve, ev3, FlowCardia, Gore, Guidant, Guided Delivery Systems, Inc., InSeal Medical, Lumen Biomedical, HLT, Kensey Nash, Kyoto Medical, Lifetech, Lutonix, Medinol, Medtronic, NDC, NMT, OAS, Occlutech, Osprey, Ovalis, Pathway, PendraCare, Percardia, pfm Medical, Rox Medical, Sadra, Sorin, Spectranetics, SquareOne, Trireme, Trivascular, Velocimed, and Veryan.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CASE REPORT
  5. DISCUSSION
  6. LIMITATION
  7. CONCLUSION
  8. ACKNOWLEDGMENTS
  9. REFERENCES
  • 1
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