Case description. A 19-year-old man, who probably suffered from Kawasaki disease (KD) from 3 years of age, presented with acute myocardial infarction and was treated with direct plain old balloon angioplasty at another hospital. Emergency coronary angiography revealed complete occlusion in the proximal segment of the right coronary artery (RCA). When the vessel was recanalized, a coronary aneurysm was found to contain severe calcification and proximal stenosis distal to the site of occlusion. Although a 3.5–15 mm Quantum balloon catheter (Boston Scientific/Scimed, Maple Grove, Minnesota) was inflated at 24 atmospheres (ATM) in the region of calcified stenosis, balloon indentation remained and the procedure was suboptimal. Three days later, he was transferred to our center to undergo rotational atherectomy. Coronary angiography revealed a large aneurysm at the previous site of occlusion (Figure 1A). Intravascular ultrasound (IVUS), Ultracross 2.9 French 30 MHz, Boston Scientific/Scimed) imaging at the site of coronary stenosis revealed a circumferential, thick, ring-shaped severe calcification (Figure 2A). The coronary aneurysm also exhibited superficial and circumferential calcification. Even after rotational ablation (Figure 1B), superficial calcification remained circumferentially with limited lumen diameter because the maximum burr diameter was only 2.5 mm (Figure 2B). A 4.0–10 mm cutting balloon (CB) catheter (Interventional Technologies, San Diego, California) was therefore used and dilated completely at 12 ATMs (Figure 1C). IVUS imaging revealed an adequately dilated lumen with 4 sites of tearing, probably caused by the four blades of the cutting balloon. The lumen diameter increased from 2.5 X 2.5 mm after rotational atherectomy to 3.6 X 3.6 mm after cutting balloon angioplasty (Figure 2C). The angiographic result was stent-like, with only 2% diameter stenosis. No major or minor complications occurred during this procedure.

       Patient management. This case suggests that treatment with a combination of cutting balloon and rotational atherectomy may have advantages for dilation of coronary stenosis even in a patient with severely calcified coronary artery stenosis due to KD.^3,6 The interval from onset of disease to intervention was, in our patient, about 16 years. This long interval might explain the severe calcification in this patient.³

Figure 1

Angiographic findings during coronary intervention. These coronary angiograms were taken 3 days after previous balloon angioplasty for AMI at another hospital. The target lesion with segmental stenosis is seen proximal to a coronary aneurysm in the mid segment of the RCA (A). A large aneurysm is also found in the proximal segment of the RCA. After evaluation by IVUS, rotational atherectomy was performed with 2.0 mm and 2.5 mm burrs (B). A 4.0–10 mm cutting balloon was used and balloon indentation completely disappeared at 12 ATMs (C). The balloon was then inflated for 120 seconds at 10 ATMs. Angiographically, the result was stent-like, and the final diameter stenosis was 2%. Ref.D = reference diameter; MLD = minimal lumen diameter; %DS = percent diameter stenosis; Rota = rotablator; CB = cutting balloon.

       Selection of an appropriate device is very important in catheter intervention for KD.^6,7 However, there are currently no established criteria for selecting new devices. Ishii et al.6 recently reported serial follow-up results of coronary intervention for 22 KD patients with 23 coronary arterial lesions. They decided on a therapeutic procedure after pathological observation of the stenosis with IVUS imaging. Stent implantation was performed in cases with comparatively mild calcification, < 50% calcification index (%) (calcification area X 100/area of intima-media complex), whereas rotational atherectomy was selected in cases with more severe calcification. In their study, when insufficient expansion was obtained with rotational atherectomy alone, stent implantation was also performed, provided that the calcification index was < 50% on IVUS imaging. According to their criteria, use of a stent was not indicated in this case due to the presence of severe calcification. We did not deploy a stent because of the excellent results obtained with CB angioplasty, although in case of restenosis we would choose stent deployment for the next procedure.

Figure 2

Two- and three-dimensional IVUS findings during coronary intervention. The stenosis was located in the proximal portion of the distal aneurysm. Two-dimensional IVUS imaging revealed a circumferential, thick, ring-shaped severe calcification (A). (Pre-intervention). The lumen is almost entirely occupied by the IVUS catheter. Even after rotational ablation, superficial calcification remained circumferentially with limited lumen diameter because the maximum burr diameter was only 2.5 mm (B) Post rotablator. The lumen was adequately dilated with 4 sites of tearing following cutting balloon angioplasty (C) Post CB. Minimal lumen diameter increased to 3.6 X 3.6 mm. MLD = minimal lumen diameter; CB = cutting balloon

       The pressure on each blade of the cutting balloon is estimated to be 157,000 times as high as that of the conventional balloon,⁹ and the blade is reported to be sharper than conventional surgical knives.8 According to Satler,⁹ a cutting balloon can exert very high forces on a plaque or calcification. If it is assumed that the force in an angioplasty balloon is equal to the balloon pressure divided by the surface area of the balloon and that the force in the cutting balloon is primarily the result of balloon pressure over the surface area of the atherotomes, quick calculation can demonstrate that the force of the cutting balloon could theoretically be as high as 157,000 times that of a standard balloon for the 4.0 mm size balloon with 4 blades (surface area of plain balloon = 3.14 X diameter X length = 3.14 X 4.0 mm X 10 mm = 125.6 mm2, surface area of the cutting balloon = 0.00002 mm X 10 mm X 4 = 0.0008 mm2). The ratio of force can be calculated from the formula: force of CB/force of plain balloon = (pressure/surface area of CB)/pressure/surface area of plain balloon) = surface area of plain balloon/surface area of cutting balloon. Thus, there is 157,000 times more force at the point of each blade. This strong force might have led to the tears observed at 4 sites in superficial calcification.

How Would you Manage this Case?
George Dangas, MD, PhD
Cardiology Research Foundation, New York, New York

       This case of Kawasaki disease is an interesting interventional problem. It is important to recognize upfront the great utility of IVUS in guiding the decision of treating any undilatable lesion, especially in the proximity of an aneurysm. IVUS may differentiate between a rather heavy calcification and a very densely fibrotic lesion with massive negative remodeling. Rotablator can be safely used in the former situation, while it may be a real hazard for major vessel perforation in the latter.
       In the present case, IVUS confirmed the presence of heavy concentric calcification at the arterial segment that precluded balloon inflation. I would use rotational atherectomy with a stepped-bur approach with a 2.25 mm and 2.5 mm burrs (maximum size available); I would place a temporary pacemaker electively. A 10 French arterial guiding catheter would be needed; I would prefer to avoid a GP IIb/IIIa inhibitor due to 1) finite risk of perforation and 2) the large guide catheter size.
       After the rotablator, I would repeat the IVUS imaging and proceed with additional balloon dilation using a 4.0 or 4.5 mm diameter, non-compliant balloon, 15–20 mm in length. After balloon dilation, I would repeat an IVUS run to exclude a major dissection, and attempt to stay away from stenting.
       Avoidance of stenting should be considered an important feature of my approach, because of the nature of Kawasaki disease and the potential to have aneurysm development at the intervention site, leading to stent malapposition and thrombosis at a later point (months or even years). I do not think that restenosis would be a major issue in this case, because of the favorable effects of 1) the very large vessel diameter, and 2) the heavily calcified nature of the target lesion.
       Finally, I would definitely recommend combination therapy with aspirin plus clopidogrel for life because of the thrombosis risk within the coronary aneurysms that this patient with Kawasaki's disease has.

Jeffrey A. Werner, MD
Mercy Health Systems of Northwest Arkansas, Rogers, Arkansas

       A pleasing angiographic result immediately post interventional procedure is a source of encouragement for both the operator and the patient. In addition, in this case, there were apparently no immediate post-procedure complications such as acute thrombosis or occlusive dissection, the latter of particular concern when not using a coronary stent post angioplasty in complex anatomy.
       Nevertheless, this is a dangerous case. I agree with the operator that attempting coronary stent placement without a considerable amount of debulking could have lead to inability to expand a stent. In this setting, an under-expanded stent would almost surely have resulted in acute or subacute thrombotic occlusion and would not have been a good choice.
       Likewise, the use of rotational atherectomy in the presence of heavy, deep circumferential calcification in complex anatomy carries an above average risk due to excessive heat build-up with the larger burr and longer run times. This is also the setting for the possibility of acute thrombosis and possible vessel perforation.
       The results of use of cutting balloon at standard lower atmospheres, particularly for in-stent restenosis, seem encouraging, but the U.S. literature awaits longer term results in various patient subsets. Whether cutting balloon can and should be used routinely at high pressures to cut dense, deep circumferential calcification remains unreported to my knowledge. However, it would seem intuitively, that applying “157,000 times” the force of a standard balloon to a coronary artery and/or small vein graft would be associated with an unfavorable risk-benefit ratio if attempted on a regular basis and would require both a pericardiocentesis needle and a cardiac surgeon close at hand. In addition, a careful review of the IVUS prints post cutting balloon suggests that the inferior third to half of the vessel was very little changed in spite of this theoretical expansive force. All of this, of course, without knowledge of the anticipated restenosis rate.
       While I agree that the patient’s age and the unusual nature of his disease warrant consideration for interventional approaches other than bypass graft surgery, until we have longer term safety and restenosis data for cutting balloon in such cases, our surgical colleagues can provide the possibility of a durable (particularly with arterial conduits) and more predictable result. While a second surgery years from now might be required, that is the nature of congenital heart diseases such as this. Hopefully, by then, we will have considerable experience with newer interventional technologies to offer with more safety and efficacy data to back it up.

Martin B. Leon, MD
Cardiology Research Foundation, Lenox Hill Hospital, New York, New York

       This case illustrates the classic combination of coronary aneurysm and heavily calcified stenosis in a young adult with a probable history of Kawasaki disease. Treatment with a non-compliant balloon inflated to 24 ATMs did not relieve the obstruction, and thus, rotational atherectomy was performed. The severe encircling superficial coronary calcification often requires rotational atherectomy, but since these are often aneurysmal or ectatic vessels, stand-alone atherectomy is rarely sufficient to achieve adequate lumen dimensions and subsequent balloon angioplasty or stenting is generally required. Normally, we would have attempted appropriately sized high pressure balloon dilatation as the intial post-atherectomy treatment. Usually, the compliance of the vessel is significantly altered with antecodent calcium removal and complete expansion is possible with simple balloon dilatation. In this case, a 4.0 mm cutting balloon was utilized and an excellent angiographic and IVUS result was achieved. Certainly, the cutting balloon is a good alternative choice in treating mild to moderate fibro-calcific obstructive lesions. Limitations of the cutting balloon in this scenario include: 1) difficulty in delivering the device across the lesion if there is important tortuosity or calcification, due to axial stiffness of the blades (should only use the 6 or 10 mm long blade devices); 2) higher frequency of perforation than with conventional balloons, mandating extra cautious device sizing; 3) limited capacity for high pressure inflations (usually 12 ATMs) due to relatively low-rated burst pressures.
       An interesting question resides in whether subsequent stent implantation is advisable or required. In this case, the angiographic and IVUS results were excellent and it would be acceptable to avoid stent placement, especially given the vessel size disparities and difficulties with stent sizing across the aneurysmal post-stenotic segment. Certainly, if restenosis occurs, the next procedure should include a stent. Importantly, with the availability of drug-eluting stents in most parts of the world, one could argue that adjunct stent placement is indicated to both reduce the likelihood of subsequent restenosis and to possibly alter the natural history of the underlying pathobiologic disease state.

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