Usefulness of the SafeCut Dual Wire PTCA Catheter for the
Treatment of Calcified Lesions

In-stent restenosis has long remained the major limitation of coronary stenting. Recent randomized trials have shown that the use of drug-eluting stents (DES) markedly reduce the risk of in-stent restenosis following treatment of de novo lesions,^1–4 even lesions at high risk for in-stent restenosis.^5,6

Calcified lesions are often undilatable with conventional balloons and are a predictor of late in-stent thrombosis.⁷ Stent underexpansion is also associated with restenosis⁸ and in-stent thrombosis after successful DES implantation.⁹ Therefore, optimal dilatation of target lesions prior to stenting remains an important factor for the prevention of restenosis and in-stent thrombosis, even in the DES era.

In this report, we describe a novel balloon catheter, the SafeCut Dual Wire percutaneous transluminal coronary angioplasty catheter (OrbusNeich Wanchai, Hong Kong), which was used to dilate a calcified lesion when a conventional balloon was unsuccessful (Figure 1).

Case Report. The patient was a 59-year-old male with coronary risk factors of hypertension, hyperlipidemia, diabetes mellitus, and smoking. He had a history of anterior myocardial infarction and a bare-metal stent was implanted in the mid-left anterior descending (LAD) coronary artery in January 2006. He was admitted to our hospital for follow-up coronary angiography and angioplasty of the residual stenosis in the mid-diagonal branch in July 2006. The coronary angiogram revealed a calcified lesion with 90% stenosis in the mid-diagonal branch (Figure 2a). Coronary angioplasty of the diagonal branch was performed with a 6 Fr XB 3.5 guiding catheter (Cordis Corp. Miami, Florida) via the right radial artery. A 0.014 inch Whisper MS hydrophilic-coated guidewire (Guidant Corp., Indianapolis, Indiana) was easily inserted into the diagonal branch, but a 40 MHz intravascular ultrasound (IVUS) probe (Atlantis Pro2; Boston Scientific Corp., Natick, Massachusetts) was unable to pass the severe calcified lesion before angioplasty. A 2.5 x 12 mm Maverick 2 conventional balloon (Boston Scientific) was placed in the lesion and inflated to 18 atm. However, thecalcified lesion could not be dilated (Figure 2b). Due to the previous failure to achieve optimal balloon expansion at 18 atm, rotational atherectomy was performed in an attempt to partially ablate the underlying calcium to allow subsequent balloon expansion. A 1.5 mm Rotablator burr (Boston Scientific) was initially used (Figure 2c) because the vessel was small. Following initial rotational atherectomy, angiography indicated a slight improvement in the lumen diameter (Figure 2d).

A 2.5 x 12 mm Maverick2 was used in an attempt to inflate up to 18 atm; however, again it would not fully expand (Figure 3a). The buddy wire technique was also unsuccessful. Subsequently, a 2.5 x 15 mm Safe- Cut balloon catheter was used. The SafeCut balloon catheter easily passed across the lesion and was gradually inflated to 12 atm until full balloon expansion was achieved (Figure 3b). Following the SafeCut balloon angioplasty, angiography showed marked improvement in the lumen diameter (Figure 3c). A 2.5 x 23 mm Cypher stent (Cordis) was successfully implanted at the mid-diagonal branch, and a final angiogram showed satisfactory results (Figure 3d). IVUS after SafeCut balloon angioplasty showed two fissures on a superficial calcified plaque (Figure 4a). Final IVUS after Cypher stent implantation showed a satisfactory lumen area (Figure 4b). This novel device may be useful for calcified lesions that are unresponsive to adequate dilatation with a conventional balloon.

Discussion

In the present case report, we demonstrated that the SafeCut balloon catheter can safely achieve optimal dilatation of an unresponsive calcified lesion at lower inflation pressures compared with a conventional balloon catheter.

It has been reported that stent underexpansion is significantly related to an increased risk of restenosis8and in-stent thrombosis,⁹ even when a DES is employed. Calcified lesions are a cause of stent underexpansion. Therefore, lesion preparation for allowing optimal stent expansion remains an essential part of the current interventional practice, and it would be particularly beneficial for patients with undilatable calcified lesions prior to DES implantation.

Several techniques, such as directional coronary atherectomy,¹⁰ rotational atherectomy^11,12 and cutting balloon¹³ for calcified lesions have been proposed to achieve optimal dilatation prior to stent implantation. The SafeCut balloon catheter is a short, monorail-type balloon catheter like an IVUS catheter, and is more flexible to deliver than a directional coronary atherectomy device or a cutting balloon. It has superb passing ability, with a lower profile (0.028 inch), and the hydrophilic coating extends 32 cm from the distal tip. It is occasionally difficult to deliver a directional coronary atherectomy device or a cutting balloon across calcified target lesions due to their large profile, particularly in calcified small vessels. In addition, a cutting balloon with 3 or 4 blades around the surface poses the risk of coronary rupture.^14,15 Rotational atherectomy is occasionally impractical for achieving optimal lumen diameter because the burr size to achieve a larger lumen and aggressive ablation depends on vessel diameter and the guiding catheter size.

The SafeCut balloon catheter is a novel semi-compliant balloon catheter with dual wires that exert focused inflation forces. It can facilitate controlled plaque fractures because the built-in integral wire and the coronary guidewire on the outside of the balloon can create a focused force in a localized region of the plaque. When used with slow, gradual inflation protocols, the SafeCut balloon enables modification of the plaque and enhances luminal gain at low inflation pressures before the balloon is fully inflated. Focused-force angioplasty is a technique in which the forces resulting from inflating an angioplasty balloon in a stenotic lesion are concentrated and focused at one or more locations within the stenosis.¹⁶ This technique, including the conventional buddy wire technique^17,18 and cutting balloon, have shown to be useful in resolving resistant stenosis.¹⁹ The buddy wire technique is easy and simple, and may be an effective technique for dilatation of calcified lesions.^17,18 In this case, we also attempted the buddy wire technique after rotational atherectomy, but it was ineffective. The built-in integral wire of the SafeCut balloon may have an important role in facilitating fractures of calcified lesions.

In this report, we demonstrated that the SafeCut balloon catheter was more effective in resistant calcified lesions than a conventional balloon, even after rotational atherectomy. The SafeCut balloon catheter was able to pass this severe calcified lesion before rotational atherectomy because of its superb passing ability. If the SafeCut balloon catheter is used before rotational atherectomy, the procedure proceeds simply and smoothly.

In this report, we demonstrated the effectiveness of a novel device using focused-force angioplasty for calcified lesions. The SafeCut balloon was successfully used to dilate a calcified lesion that was resistant to conventional balloon angioplasty.

Acknowledgement. The authors gratefully acknowledge the technical support of Mr. Ryusuke Higashi for intravascular ultrasound.

References

1. Morice MC, Serruys PW, Sousa JE, et al. A randomized comparison of a sirolimus-eluting stent with a standard stent for coronary revascularization. N Engl J Med 2002;346:1773–1780.

2. Moses JW, Leon MB, Popma JJ, et al. Sirolimus-eluting stents versus standard stents in patients with stenosis in a native coronary artery. N Engl J Med 2003;349:1315–1323.

3. Colombo A, Drzewiecki J, Banning A, et al. Randomized study to assess the effectiveness of slow- and moderate-release polymer-based paclitaxel-eluting stents for coronary artery lesions. Circulation 2003;108:788–794.

4. Stone GW, Ellis SG, Cox DA, et al. A polymer-based, paclitaxel-eluting stent in patients with coronary artery disease. N Engl J Med 2004;350:221–231.

5. Schofer J, Schluter M, Gershlick AH, et al. Sirolimus-eluting stents for treatment of patients with long atherosclerotic lesions in small coronary arteries: Doubleblind, randomized controlled trial (E-SIRIUS). Lancet 2003;362:1093–1099.

6. Schampaert E, Cohen EA, Schluter M, et al. The Canadian study of the sirolimus-eluting stent in the treatment of patients with long de novo lesions in small native coronary arteries (C-SIRIUS). J Am Coll Cardiol 2004;43:1110–1115.

7. Urban P, Gershlick AH, Guagliumi G, et al; e-Cypher Investigators. Safety of coronary sirolimus-eluting stents in daily clinical practice: One-year follow-up of the e-Cypher registry. Circulation 2006;113:1434–1441.

8. Sonoda S, Morino Y, Ako J, et al; SIRIUS Investigators. Impact of final stent dimensions on long-term results following sirolimus-eluting stent implantation: Serial intravascular ultrasound analysis from the SIRIUS trial. J Am Coll Cardiol 2004;43:1959–1963.

9. Fujii K, Carlier SG, Mintz GS, et al. Stent underexpansion and residual reference segment stenosis are related to stent thrombosis after sirolimus-eluting stent implantation: An intravascular ultrasound study. J Am Coll Cardiol 2005;45:995–998.

10. Takagi T, Di Mario C, Stankovic G, et al. Effective plaque removal with a new 8 French-compatible atherectomy catheter. Catheter Cardiovasc Interv 2002;56:452–459.

11. Kobayashi Y, Teirstein P, Linnemeier T, et al. Rotational atherectomy (stentablation) in a lesion with stent underexpansion due to heavily calcified plaque. Catheter Cardiovasc Interv 2001;52:208–211.

12. MacIsaac AI, Bass TA, Buchbinder M, et al. High speed rotational atherectomy: Outcome in calcified and noncalcified coronary artery lesions. J Am Coll Cardiol 1995;26:731–736.

13. Asakura Y, Furukawa Y, Ishikawa S, et al. Successful predilation of a resistant, heavily calcified lesion with cutting balloon for coronary stenting: A case report. Cathet Cardiovasc Diagn 1998;44:420–422.

14. Maruo T, Yasuda S, Miyazaki S. Delayed appearance of coronary artery perforation following cutting balloon angioplasty. Catheter Cardiovasc Interv 2002;57:529–531.

15. Quan VH, Stone JR, Couper GS, et al. Coronary artery perforation by cutting balloon resulting in dissecting subepicardial hematoma and avulsion of the vasculature. Catheter Cardiovasc Interv 2005;64:163–168.

16. Solar RJ, Ischinger TA. Focused force angioplasty: Theory and application. Cardiovasc Radiat Med 2003;4:47–50.

17. Vijayvergiya R, Swamy AJ, Grover A. Buddy wire technique: A simple technique for treating calcified lesion during percutaneous coronary intervention: A case report. J Invasive Cardiol 2006;18:E129–30.

18. Hussain F, Kashour T, Rajaram M. Ostial RCA intervention: Guiding catheter challenges and use of a buddy wire to perform focused-force angioplasty on a severely calcific ostial right coronary lesion. J Invasive Cardiol 2006;18:E298–301.

19. Barath P, Fishbein MC, Vari S, et al. Cutting balloon: A novel approach to percutaneous angioplasty. Am J Cardiol 1991;68:1249–1252.