Management of Resistant Coronary Lesions by theCutting Balloon Catheter: Initial Experience

Olivier F. Bertrand, * MD, Raoul Bonan, MD, Luc Bilodeau, MD, Jean-Franc ois Tanguay, MD,Jean-Claude Tardif, MD, Josep Rode s, MD, Michel Joyal, MD, Jacques Cre peau, MD,

and Gilles Coˆ te, MD

Resistant coronary lesions remain a challenge for modern angioplasty. Classical ap-proaches include high-pressure inflations, prolonged inflations, or balloon oversizing.More recently, new technologies like rotablator, atherectomy, or laser have been proposedas adjunct to balloon angioplasty for the treatment of these specific lesions. However, allthese technologies remain more difficult to handle, costly, and they do not offer long-termbenefit over conventional methods. Therefore, a simple device such as the cutting ballooncatheter which has been developed from a standard over the wire balloon catheter, mayprove to be useful in resistant coronary lesions. We present our single center experienceusing the new cutting balloon catheter in six resistant lesions. Cathet. Cardiovasc. Diagn.41:179–184, 1997. r 1997 Wiley-Liss, Inc.

Key words: coronary lesions; angioplasty; cutting balloon

INTRODUCTION

Since the first human coronary angioplasty by A.Gruentzig, many technological advances in the develop-ment of balloon catheters have broadened indications andallowed the treatment of more complex lesions. Recently,Myler et al. reported success rates of 99% in type A, 92%in type B, and 90% in type C lesions [1]. Meanwhile,alternative devices such as laser, rotablator, and atherec-tomy catheters have been developed to approach complexlesions which appear less suitable for balloon angioplasty.Resistant coronary lesions remain a challenge for

modern angioplasty. Classical approaches to dilate theselesions include high-pressure inflations, prolonged infla-tions, and slight balloon oversizing. Even with theseapproaches, a few coronary lesions cannot be success-fully dilated. One alternative technique includes thebuddy wire dilation with one or two guidewires passedalongside a conventional balloon catheter. Once inflated,the guidewire is believed to exert a focused force,allowing plaque rupture [2,3]. Another approach, thehugging balloon technique, involves simultaneous infla-tions of two balloon catheters at the critical stenosis level[4]. Using a multi-device, lesion-specific approach, Leonand coworkers advocated the use of laser, atherectomy,and stenting for the treatment of unsuccessful PTCAresults [5].The cutting balloon is a standard, over-the-wire bal-

loon catheter which has been developed by Peter Barathand is manufactured by IVT technologies. Three to fourmicroblades (depending on the balloon size) are longitu-

dinally attached to the balloon and are intended to scorethe plaque once the balloon is inflated. Thesemicrotomes,approximately 0.25 mm in height, are 3 to 5 times sharperthan conventional surgical blades. The microsurgicaldilatation is based on stress fracture mechanics [6]. Themicrotome edge initiates an indentation into the plaque,after which the shear force applied by the ballooninflation propagates the crak [7]. Depending on balloonsize, the cutting force at the blade edge is enhanced200,000 to 400,000 times [8]. Due to that peculiarmechanism of action, we assumed a possible role for thetreatment of resistant coronary lesions. We describe sixpatients with coronary lesions that could not be dilated byconventional balloon angioplasty and were successfullytreated by cutting balloon angioplasty. The treatment ofresistant coronary lesions is reviewed and the potentialapplications of the cutting balloon technique are pre-sented.

CASE REPORTS

Case 1

A 66-year-old patient with previous history of myocar-dial infarction in 1973 underwent bypass surgery (CABG)

Montreal Heart Institute, Montreal, Quebec, Canada

*Correspondence to: Olivier Bertrand, M.D., Interventional Cardiol-ogy Laboratories, Montreal Heart Institute, 5000 Be´langer, Montre´al,Quebec, Canada, H1T 1C8.

Received 16 October 1996; Revision accepted 23 January 1997

Catheterization and Cardiovascular Diagnosis 41:179–184 (1997)

r 1997 Wiley-Liss, Inc.

in 1976 and in 1990. In July 1994, he presented withcrescendo angina and angiography showed a severestenosis on the mid portion of the saphenous vein graft(SVG) to the right coronary artery (RCA). Left ventricu-logram showed moderate postero-basal hypokinesia andejection fraction of 60%. Standard balloon inflations withincremental balloon diameters from 2.5 to 4 mm (max.balloon artery/ratio: 0.9) (Pronto, USCI, Free-hand andMongoose, Schneider) and inflation pressures up to 24atm for 290 sec did not produce any significant improve-ment. A single inflation of a 3.5-mm diameter, 10-mm-long cutting balloon at 8 atm for 4 min finally succeededin dilating the lesion with a 20 % residual stenosis. Then,a Palmaz-Schatz stent manually crimped on a Mongoose4-mm diameter was positioned at the dilated site. Furtherinflations with a 4.5-mm Monorail Mega (Schneider)inflated at 16 atm led to excellent angiographic andintravascular ultrasound (IVUS) results. The IVUS studydid not reveal any calcification on the proximal and distalreference segments.

Case 2

A 67-year-old patient with a previous history ofmyocardial infarction in 1993 underwent CABG with aleft mammary artery (LIMA) anastomosed to the leftanterior descending artery (LAD) and a sequential SVGto the posterior descending (PDA), the first marginalbranch and the first diagonal in 1994. In May 1995,angiography for recurrent angina showed a weblikelesion in the midportion of the SVG. Left ventriculogramwas normal, with an ejection fraction of 68%. Angio-plasty with a 3.5-mm diameter balloon (Titan, Cordis) upto 25 atm left a residual stenosis of 40%. Despite highpressure, the balloon had never been fully expandedduring the procedure. In June 1995, the patient wasreadmitted with unstable angina and angiography re-vealed severe restenosis at the same site. At this stage, thepatient was referred to our hospital for a possible cuttingballoon procedure. During transfer, the patient had uncon-trolled severe chest pain and upon arrival was brought tothe catheterization laboratory in cardiogenic shock with 3mm ST depression in antero-lateral and inferior leads.The lesion was easily crossed with the guidewire (Very-Flex, USCI) but inflations with balloons of 3.5 mmdiameter (Europass, Cordis and High-energy, Mansfield)with inflation pressures up to 25 atm for 330 sec (max.balloon:artery ratio5 1.37) failed to produce any lesionchanges with a persistent waist on the inflated balloon andmultiple balloon ruptures. Finally, two inflations with acutting balloon of 3.5-mm diameter at 10 atm success-fully dilated the lesion, but a type C dissection led toimplantation of a Palmaz-Schatz stent at the intended site.Additional inflations with a 3.5-mm diameter balloon(Chubby, Schneider) inflated up to 16 atm led to good

stent apposition as assessed by IVUS. Again, IVUS didnot show any calcifications of the proximal and distalsegments.

Case 3

A 71-year-old man underwent a first bypass surgery in1973 and redo surgery in 1981 with a SVG sequentiallyanastomosed to the LAD and the first diagonal. In 1995,he was readmitted for unstable angina and angiographyrevealed a severe lesion in the proximal part of the SVG.Left ventriculogram was normal with an ejection fractionof 62%. Successive inflations with balloons of 2.5 mmdiameter at 10 atm (Europass, Cordis) then 5 mmdiameter at 20 atm for 100 sec (max. balloon:artery ra-tio 5 1.5) (Mega, Schneider) were characterized byincomplete balloon expansions. These very high pres-sures led to repetitive balloon ruptures. After a failedbuddy wire technique attempt using a 5 mmdiameterballoon (Mega, Schneider) and a 0.018-in. parallelguidewire (Reflex supersoft, Cordis), two inflations at 12atm with a 4-mm diameter, 10-mm-long cutting balloonwere performed, leading to complete balloon expansion.However, a significant residual stenosis persisted andfurther dilations were accomplished using a 5-mm-diameter balloon at 22 atm for 5 min (Monorail Mega,Schneider). Finally, a Palmaz-Schatz stent (PS 204, 20mm long) was deployed with a 4-mm-diameter balloon(Mongoose, Schneider) and a 5-mm-diameter short bal-loon (Chubby, Schneider) at 20 atm. Similarly, IVUS didnot show any calcification of the adjacent segments.

Case 4

A 59-year-old woman who had undergone coronaryartery bypass surgery in 1994 was hospitalized withunstable angina. Selective coronary angiography revealedmildly diseased left coronary tree with a patent mammaryartery grafted to the mid-LAD and a widely patent SVGto the PDA. However, the nongrafted right coronaryartery was severely narrowed at its midportion. Leftventriculogram was normal with an ejection fractiongreater than 55%. Despite optimal medical therapy,recurrent chest pain required angioplasty of the tightlesion in her native right coronary artery. Many attemptsat dilating this stenosis using 2.5- and 3.0-mm-diameterballoons (Titan, Cordis) (max. balloon:artery ratio5 0.9)with inflation pressures up to 20 atm, even with anadditional parallel 0.014-in. guidewire (Very Flex, USCI),did not produce any significant improvement. The patientwas then transferred to our institution for further treat-ment. A 2.75-mm/10-mm-long cutting balloon, mountedon a 0.014 Very flex wire (USCI) was positioned withsome difficulty at the middle of the lesion. A single 3 mininflation at 6 atm produced good angiographic result with

180 Bertrand et al.

a residual 39% stenosis and no further dilatation wasperformed.

Case 5

A 62-year-old man who had undergone previous by-pass surgery in 1980 with two SVGs on the LAD and thePDA, presented with unstable angina in September 1995.Angiography showed a severe stenosis of the PDA, distalto the anastomosis. Left ventriculogram showed severehypokinesia of the inferior wall with moderate hypokine-sia of the anterolateral wall and an ejection fraction of55%. The lesion was resistant to prolonged inflations withballoon catheters from 3.5 to 4 mm in diameter (Euro-pass, Cordis) (max. balloon:artery ratio5 0.9), andpressures up to 16 atm for 200 sec. Attempts to cross witha cutting balloon of 3.5-mm diameter, 10 mm long failed.Using a 7 Frguiding catheter allowing deep seating intothe saphenous graft, a 3-mm-diameter, 10-mm-long cut-ting balloon crossed the lesion and successfully dilatedthe stenotic segment with a single 8 atm inflation for 90sec. Additional inflations with 3.5-mm-diameter balloons(Europass, Cordis and High energy, Mansfield) up to 16atm were necessary to obtain a good angiographic resultwith a residual stenosis#30%.

Case 6

A 63-year-old woman with a previous history ofantero-lateral myocardial infarction underwent bypasssurgery in 1986 with a LIMA to the LAD and a SVG to apostero-lateral branch of the RCA. In January 1996, shepresented with unstable angina and left ventricular fail-ure. Angiography showed severe stenosis on the proximalRCA and moderate stenosis on the PDA. The LIMA waswidely patent but the SVG was occluded. Severe leftventricular dysfunction was noted with diffuse hypokine-sia, antero-lateral akinesia and ejection fraction of 26%.In that context, she was referred for dilatation of theRCA. Balloon diameters from 1.5 mm to 2.5 mm (Sleek,Cordis) (max. balloon:artery ratio5 0.9) and inflationpressures up to 20 atm for more than 20 min did notsucceed in breaking the lesion (cf. Fig. 1). A 2-mm-diameter, 10-mm-long cutting balloon at 8 atm was firstused. Then a second 2.5-mm, 10-mm-long cutting bal-loon inflated at 9 atm for 180 sec left a residual stenosis of25% (cf. Fig. 2). A final inflation with a 2.5-mm-diameterballoon (Europass, Cordis) at 18 atm for 90 sec wasperformed but did not produce any angiographic change.During the same procedure, the distal lesion of the PDAwas successfully dilated with a 2.0-mm-diameter balloonat 13 atm for 600 sec (Europass, Cordis). A few hourslater, the clinical course was complicated by untractableventricular fibrillation and the patient died despite cardio-pulmonary reanimation. Autopsy revealed that both di-lated sites on the RCAwere patent without signs of acute

necrosis in that territory but showed a ruptured plaque inthe left main stem with a recent extensive transmuralanterol-lateral myocardial infarction.

PATHOLOGIC ASPECTS OF CUTTINGBALLOON ANGIOPLASTY

To analyse the effects of cutting balloon dilation onhuman atherosclerotic lesions, we compared the proximaland distal dilated sites of patient 6 (Figs. 3 and 4). Thedistal dilated site of the right coronary artery showedsome classical aspects described after standard balloonangioplasty (Fig. 3). In this concentric lesion, moderateplaque compression and a small intimal flap surroundedby some intraplaque hemorrhage were recognized. Plaquefracture, intimal flap, localized medial dissection, plaquecompression, and vessel wall stretching have been pro-posed as mechanisms of successful coronary angioplastyin humans [9,10] The proximal site was dilated, asdescribed previously, with two cutting balloons and oneconventional balloon (Fig. 4).The coronary artery was not pressure-fixed, but one

could easily recognize six different small incisions intothe plaque resulting from the different cutting balloonsused. In addition a mild intraplaque hemorrhage wasrecognized. Therefore, we can assume that the mecha-

Fig. 1. Angiographic aspects of the right coronary artery(patient 6). A: Lateral view before angioplasty showing a severeproximal lesion. B: Lateral view showing a persistent waist onstandard balloon catheter.

Angioplasty of Resistant Coronary Lesions 181

nism of action of the cutting balloon involved at leastpartially small, sharp and regular incisions of the plaque.The lumen enlargement probably resulted from wideningof these initial cuts obtained through balloon expansions.In this particular case, the presence of an hemorrhagemay be due to a deep cut of a microblade but may also bethe consequence of the high-pressure dilations used priorto the cutting balloon.

DISCUSSION

We report our initial experience with the use of cuttingballoon angioplasty in six patients with high-pressureresistant coronary lesions. Improvements in catheterdesigns and material now allow inflation pressures over20 atm for selected catheters. However, the majority oflesions are usually dilated with pressures below 10 atm.Kahn et al. reported the relation between inflation pres-sure and balloon expansion. In a prospective cohort of100 patients, the inflation pressure required to achievefull expansion was#8 atm in 92% and#10 atm in 98%of cases. Only two lesions required inflation pressuresabove 16 atm [11]. In 1990, the same group analyzed thecause of failed PTCA with modern balloon catheters. Of3,398 lesions attempted, only 20 (0.6%) could not bedilated despite high-pressure inflations, often leading torepeated balloon ruptures [12]. Thus, resistant coronarylesions remain infrequent in modern angioplasty practicebut represent a significant challenge for the interventionalcardiologist. Our initial experience involves six patients

Fig. 2. Angiographic aspects of the right coronary artery(patient 6). A: LAO view showing results after standard balloonangioplasty. B: Complete expansion of the cutting balloon. C:Final result after proximal and distal balloon dilations.

Fig. 3. Distal site after standard balloon angioplasty (patient 6)(see text). 364. Hematoxylin/phloxin/safran. Figure courtesy ofDr. T.K. Leung, Pathology Department, Montreal Heart Institute.

182 Bertrand et al.

recruited from a total of 3,090 coronary angioplastiesperformed over a period of 19 mo.Although calcified or eccentric lesions are often men-

tioned as the potential reason for resistance to usualpressures, Khan et al. did not find any consistent angio-graphic characteristics of lesions requiring high pressures(.10 atm) during coronary angioplasty [11]. In ourexperience, calcifications were visible at fluoroscopy inonly one case (case 4); and IVUS, performed in threecases (cases 2, 3, 5) after stenting in SVGs revealed nosignificant calcification in the proximal or distal referencesegments. At autopsy (case 6), the right coronary arterydid not show any calcification either; thus dense fibrosismay essentially account for these so called resistantlesions.Usual strategies to dilate resistant lesions include

longer inflations, higher inflation pressures and largerballoon diameters [13,14]. Whether high-pressure infla-tions are associated with more complications is somewhatcontroversial. Morice et al. reported a cumulative rate of

major complications of 10.2% with pressures between 13and 20 atm in comparison with 3.5% for inflationpressures between 10 and 12 atm. These investigatorsreported a 22% rate of dissection in the group with higherpressures, which may be partly due to the high rate ofballoon rupture (20.4 % vs. 3.5%) [15]. Balloon rupturemay be associated with severe complications, especiallywhen a high-pressure contrast jet creates a subintimaldissection [16]. Ebersole et al. compared immediateresults after balloon angioplasty in three different infla-tion pressure groups. Success was 90% in group 1 (1–6atm), 96% in group 2 (7–12 atm), and 95% in group 3(13–20 atm). Overall, high-pressure inflation require-ments were not associated with increased complicationsin their study [17].As extremely high inflation pressures are sometimes

required, different authors have advocated the use ofnoncompliant polyethylene terephtalate (PET) ballooncatheters, but still some lesions cannot be successfullydilated. Feld et al. described a technique using two PETballoons (Hugging balloon dilation), inflated simulta-neously at 12 atm to dilate a multiresistant lesion [4].However, it requires to cross the lesion with twoguidewires and two balloons, which might be difficult incase of severe stenosis. The same disadvantage existswith the so called buddy wire technique proposed byYazdanfar et al. [2]. With this approach, a guidewire ispassed alongside a conventional balloon. Once the bal-loon is inflated at high pressure, the adjacent wire acts asa focused force to dilate the lesion. Theoretically, thistechnique will only be successful if the parallel guidewireis optimally placed in front of a rigid atheroscleroticplaque. This technique was tried in two of our patientswithout success. New technologies like rotablation, ather-ectomy or laser angioplasty have also been proposed incase of failed angioplasty or for lesions which seemunsuitable for balloon angioplasty [5,18,19]. With thismulti-device approach, Leon et al. reported 98% angio-graphic success in 85 undilatable lesions. However,adjunctive balloon angioplasty was needed in 75% of thecases [5]. All these techniques remain more difficult tohandle, costly, and in particular, have never shown anylong-term benefit over conventional balloon angioplasty.Therefore, their use is restricted nowadays to limitedcenters and for very specific lesions.There are limitations to the use of the cutting balloon.

Due to the microblades, the profile of the cutting balloonis not ideal and improvement in the profile is awaited. Incase of true eccentric lesion or very rigid plaque, themicroblades could score the healthy vessel wall andcreate a significant dissection. In this preliminary experi-ence, 5 out of 6 patients required additional balloonangioplasty or stent implantation (Table I). In all stentimplantations, IVUS demonstrated good stent deploy-

Fig. 4. Proximal site after cutting balloon and standard balloonangioplasty (patient 6) (see text). Figure courtesy of Dr. T.K.Leung, Pathology Department, Montreal Heart Institute.

Angioplasty of Resistant Coronary Lesions 183

ment despite the initial nature of the lesions. Therefore, itis also possible that cutting balloon would be very helpfulin predilating lesions before stent placement.In conclusion, the cutting balloon offers a novel and

simple strategy for coronary lesions resistant to conven-tional balloon angioplasty. The advocated mechanismmay be controlled dissection by the microblades, whichscore first the resistant plaque. However, the role ofadjunctive therapy needs to be further defined andlong-term results will need to be determined in thisunusual subset of coronary lesions.

REFERENCES

1. Myler RK, Shaw RE, Stertzer SH, Hecht HS, Ryan C, RosenblumJ, Cumberland DC, Murphy MC, Hansell HN, Hidalgo B: Lesionmorphology and coronary angioplasty: Current experience andanalysis. J Am Coll Cardiol 19:1641–1652, 1992.

2. Yazdanfar S, Ledley GS, Alfieri A, Strauss C, Kotier MN: Parallelangioplasty dilatation catheter and guide wire:Anew technique forthe dilatation of calcified coronary arteries. Cathet CardiovascDiagn 28:72–75, 1993.

3. Stillabower ME: Longitudinal force focused coronary angioplasty:A technique for resistant lesions. Cathet Cardiovasc Diagn 32:196–198, 1994.

4. Feld H, Valerio L, Shani J: Two hugging balloons at high pressuressuccessfully dilate a lesion refractory to routine coronary angio-plasty. Cathet Cardiovasc Diagn 24:105–107, 1991.

5. Leon MB, Kent KM, Satler LF, Popma JJ, Cooke RH, Stark KS,Donovan KM, Witt JM, Shotts PA, Pichard AD: A multi-devicelesion-specific approach for unfavorable coronary anatomy (Ab-stract). J Am Coll Cardiol 19(3):93 A, 1992.

6. Blake A: ‘‘Practical Stress Analysis in Engineering Design.’’Marcel Dekker Inc, 1990.

7. Blake A: A mechanical evaluation of the dilatation of atheroscle-

rotic disease with the Barath surgical dilatation balloon system.IVT Technical Report Series 2(2), 1993.

8. Michiels R: Cutting balloon system technology: The engineeringperspective. J Inv Cardiol 8:6A–8A, 1996.

9. Block PC: Mechanism of transluminal angioplasty. Am J Cardiol53:69C–71C, 1984.

10. Mizuno K, Kurita A, Imazeki N: Pathological findings afterpercutaneous transluminal coronary angioplasty. Br Heart J 52:588–590, 1984.

11. Kahn JK, Rutherford BD, McConahay DR, Hartzler GO: Inflationpressure requirements during coronary angioplasty. Cathet Cardio-vasc Diagn 21:144–147, 1990.

12. Kahn JK, Hartzler GO: Frequency and causes of failure withcontemporary balloon coronary angioplasty and implications fornew technologies. Am J Cardiol 66:858–860, 1990.

13. Bush CA, Ryan JM, Orsini AR, HennemannWW: Coronary arterydilatation requiring high inflation pressure. Cathet CardiovascDiagn 22:112–114, 1991.

14. Willard JE, Sunnergren K, Eichhorn EJ, Grayburn PA: Coronaryangioplasty requiring extraordinarily high balloon inflation pres-sure. Cathet Cardiovasc Diagn 22:115–117, 1991.

15. Morice MC, Lafont A, Sami Y, Royer T, Glatt B: Do high pressureresisting lesions increase the risk of coronary angioplasty? Circula-tion 86(4):I–786, 1992.

16. LeMay MR, Beanlands DS: Pinhole balloon rupture duringcoronary angioplasty causing rupture of the coronary artery. CathetCardiovasc Diagn 19:91–92, 1990.

17. Ebersole DG, Rubal BJ: High balloon dilatation pressures inpercutaneous transluminal coronary angioplasty are not associatedwith higher rate of significant complications. Cathet CardiovascDiagn 35:198–202, 1995.

18. Israel DH, Marmur JD, Sanborn TA: Excimer laser-facilitatedballoon angioplasty of a nondilatable lesion. J Am Coll Cardiol18:1118–1119, 1991.

19. Brogan E, Popma J, Pichard A, Satler L, Kent K, Leon M:Rotational coronary atherectomy after unsuccessful coronary bal-loon angioplasty. Am J Cardiol 71:794–798, 1993.

TABLE I. Angioplasty and Procedure Data

VxaRef.diam.b

Bal.diam.c

Bal./art.ratiod

Max. infl.pressuree

Tot. infl.timef Rupture

Buddywire

Cbdiam.g

Cb/art.ratioh

Max. infl.pressurei

Infl.timej

MLDk

1lMLD2m

MLD3n

MLD4o

#1 SVG 4.54 4 0,9 24 18 2 2 3.5 0,8 8 4 2.13 — 3.17 4.08#2 SVG 2.55 3.5 1,37 25 11 1 2 3.5 1,37 10 2 0.47 1 3.22 3.44#3 SVG 3.32 5 1,5 20 7 1 1 4 1,2 10 3 0.69 — 2.17 4.15#4 RCA 3.41 3 0,9 20 5 1 1 2.75 0,8 6 3 0.59 — 1.95 1.95#5 RCA 3.17 4 1,3 16 10 1 2 3 0,9 8 3 0.72 — 2.38 3.36#6 RCA 2.9 2.5 0,9 20 19 2 2 2.5 0,9 9 3 0.54 0.92 2.09 1.99aVx: Vessel.bRef. diam.: Reference diameter.cBal. diam.: Balloon diameter.dBal./art. ratio: Balloon/artery ratio.eMax. infl. pressure: Maximal inflation pressure.f Tot. infl. time: Total inflation time (minutes).gCb. diam.: Cutting balloon diameter.hCb/art. ratio: Cutting balloon ratio.iMax. infl. pressure: Maximal inflation pressure.jInfl. time: Inflation time (minutes).kMLD: Minimal lumen diameter.lMLD 1: MLD before balloon angioplasty (BA).mMLD 2: MLD after BA.nMLD 3: MLD after cutting balloon.oMLD 4: Final MLD.

184 Bertrand et al.