Cutting Balloon Angioplasty for Aortic Coarctation

ABSTRACT: Background. Cutting balloon angioplasty (CBA) has improved outcomes for resistant stenotic vascular lesions in adult coronary artery disease. Application of this technique in coarctation of the aorta (CoA) in children has not been reported. Objective. We sought to review the safety, efficacy and outcomes of CBA in the setting of CoA. Methods and Results. Between February 2004 and October 2007, 8 children (4 males) underwent 10 procedures. The median age was 5.5 months (range: 2.5 months to 5 years) and median weight 7.5 kg (range: 4.1–13.3 kg). Two children had native CoA. CBA was employed due to a persistent waist after conventional balloon angioplasty (6 procedures) or as the primary dilatation (4 procedures). The cutting balloon diameter was a median 143% (range: 108–222%) of the diameter of the lesion. After dilatation, all children underwent further conventional balloon angioplasty. The CoA median diameter increased from 2.8 mm (range: 1.8–4 mm) to 4 mm (range: 2.9–6.7 mm; p = 0.0018), and the arm-to-leg blood systolic blood pressure gradient decreased from 38.5 mmHg (range: 2–70 mmHg) to 7 mmHg (0–30 mmHg; p Methods A review of the interventional database at the Hospital for Sick Children in Toronto, Ontario, Canada, was performed between January 2004 and October 2007 for all children who underwent balloon angioplasty for CoA. Parental consent was obtained for all procedures. Patient clinical, angiographic and hemodynamic data were obtained after institutional review board approval. The cutting balloon. The cutting balloon (CB) is a dilatation balloon made of noncompliant modified polyethylene terephthalate and available with inflated outer diameters ranging from 2–8 mm, in lengths of 10, 15 and 20 mm (Boston Scientific Corp., Natick, Massachusetts). Either 3 or 4 microsurgical blades (made of microtome-grade stainless steel) are bonded longitudinally around the balloon every 90° or 120°, depending on the balloons diameter, and have a working height of 0.11–0.18 mm. Before inflation, the folds of the balloon cover the microsurgical blades and after deflation, the blades wrap into the folds of the balloon. When the CB is inflated, the blades score the tissue. This process is thought to allow a more controlled tear during the subsequent dilatation. The manufacturer’s recommendation is to use a long sheath to engage the target lesion, 4 Fr for a 4 mm CB, 6 Fr for 5 and 7 Fr for the 6–8 mm balloons. Technique. General anesthesia was used in all procedures. Vascular access was obtained percutaneously from the right femoral artery and selective angiography was performed using standard techniques in two projections (15–20° left anterior oblique and left lateral with 100º caudal angulation) to define the lesion morphology. After vascular access was achieved and 150 IU/kg of heparin sulfate was administered (maximum dose 5,000 IU) with an additional 75 IU/kg given if the duration of the study exceeded 2 hours. The size of the CB was chosen to be 1 or 2 mm larger than the waist on the angioplasty balloon.8 Because of the direct course to the target lesion, a long guide sheath was not employed. A 0.014 inch Wizdom coronary guidewire (Cordis Corp., Miami Lakes, Florida) was used to cross the lesion. One or two inflations to a developed pressure of 10 atm were performed, rotating the balloon to allow the vessel to be scored throughout the lesions circumference. After CBA, all children underwent conventional balloon angioplasty with balloon diameters generally chosen to be equal to or 1–2 mm larger then the diameter of the aorta proximal to the stenotic site and not greater than the diameter of the aorta at the level of the diaphragm (Cordis Opta Pro, Cordis Europa, The Netherlands, LJ Roden, The Netherlands; Tyshak and Tyshak Mini, Numed, Hopkinton, New York; CrossSail coronary catheter, Abbott Vascular, Santa Clara, California). Repeat aortography was performed, and if no significant change in lesion diameter was noted (an increase within 80–90% of the diameter of the aortic isthmus), the next larger angioplasty balloon diameter was used. Short inflation times were employed (Results Between February 2004 and October 2007, 8 children (4 males) underwent 10 procedures using CBA as a component of the intervention to treat CoA. The median age at catheterization was 5.5 months (range: 2 ½ months to 5 years) and the median weight was 7.5 kg (range: 4.1–13.3 kg). Patient profiles and CoA characteristics are presented in Table 1. In 6 procedures, CBA was performed due to a persistent waist during conventional balloon angioplasty at rated intra-balloon pressures. In the other 4 children, the CB was used as initial dilating balloon. One child had a discrete native lesion, and the remainder had recurrent tubular lesions after previous surgery. All children had associated hypoplasia of the aortic arch and/or a diffuse vasculopathy (Williams syndrome, PHACES syndrome, Table 2). A 3 mm diameter CB was used in 1 procedure, a 4 mm CB in 8 and a 5 mm CB in 2 procedures (Table 2). One child (#5) with a long tubular lesion required 3 inflations — 1 per each area of narrowing during 2 separate procedures (Figure 3). In 1 child (#7) with Williams syndrome and previous arch reconstruction, a 3 mm CB was used initially due to the presence of an aneurysm after surgery in the vicinity of the lesion. After conventional balloon angioplasty was performed, the CB was upsized to 4 mm. This child required another intervention 1 month later; the size of the preexisting aneurysm was unchanged and no new lesions were observed. The procedure was acutely successful in 8 of 10 interventions and suboptimal in 2 (Table 3). Of the 13 lesions addressed only 1 failed to improve angiographically. This was a child with PHACES syndrome (#5) with a tubular coarctation extending from the isthmus to the level of the diaphragm. In 1 child (#1) with severely decreased left ventricular function at presentation and a long segment lesion, the arm-to-leg blood pressure gradient increased after the procedure with the increase in the diameter of the lesion thought to be due to improved cardiac function (Table 3). For the entire cohort, the CB was a median of 143% larger than the diameter of the CoA (range: 108–222%; Table 2) and the CoA diameter increased from a median of 2.8 mm (range: 1.8–4.0 mm) to 4.0 mm (range: 2.9–6.7 mm; p = 0.0018, Figure 1). The arm-to-leg blood systolic blood pressure gradient by cuff decreased from a median of 38 mmHg (range: 2–70 mmHg) to a median of 7 mmHg (0–30 mm Hg; p Discussion The CB has been used to address resistant vascular stenosis. As such, its application has extended from coronary artery lesions9 to including renal, carotid, vascular graft, aortopulmonary collaterals10,11,13,14 and more recently, pulmonary arterial stenoses.6–9 The benefit of CBA relies on the creation of micro tears in the vascular intima of the resistant lesion, weakening the fibrous skeleton, and allowing for a more effective balloon dilatation of the tissue.15 In addition to the improved mechanical efficiency, this approach has been shown to induce a lower inflammatory response.16 Studies have also suggested that there may be a lower risk for dissection, aneurysm formation and vessel perforation.17 In the setting of balloon-resistant peripheral pulmonary artery stenosis, CBA results in significant lesion enlargement when dilating balloon diameters > 200% of the minimal luminal diameter are employed8,9 with little subsequent luminal loss after dilatation. While similar in some respects to the peripheral lesions treated with CBA, aortic coarctation has different morphological, hemodynamic and technical characteristics. In particular, a larger target diameter requires larger CBs to score the vessel (presently the largest diameter CB is 8 mm). Additionally, aortic wall histology is different from that of the coronary or pulmonary arteries, where the presence of ductal tissue in young infants constitutes a substrate for potential recoil. Finally, the higher aortic pressure may potentially aggravate the consequences of complications such as dissection, aneurysm formation or rupture. To date, there is no literature guiding the choice of a CB diameter in this setting. In this experience, 8 children had resistant heterogeneous aortic arch lesions with respect to length and the presence of multiple involved segments. As an initial guide, we transposed the experience from peripheral pulmonary artery stenosis when choosing a CB. As experience was gained, 4 more recent interventions were performed before conventional angioplasty, based on the angiographic (arch, isthmus, descending aorta z scores) and clinical (prior history of a resistant lesion) predictors of potentially suboptimal results. This approach was also translated to the application of CBA to a child with native CoA based upon the appearance (subjective) of the lesion and prior experience with the CB (Figure 4). In the other 6 interventions, the persistence of a waist during conventional balloon dilatation supported use of the CB. The observation that the waist, present at the initial dilatation with a conventional balloon, disappeared when repeated with the same-sized balloon after CBA supports the notion that further luminal gain was achieved. However, the small number of children prevents a robust analysis correlating CB to CoA diameter ratio. Children who redeveloped a significant arm-to-leg blood pressure gradient and/or required a repeat intervention were those with syndromic, diffuse vasculopathies (Williams and PHACES syndromes). In 1 child with a non-syndromic diffuse vasculopathy (#4), a progressive decrease in the arm-to-leg blood pressure gradient was observed over time. The high incidence of vascular complications may be related to difficulty of access in children with CoA, previous interventions or an intrinsic generalized vascular abnormality seen in this select group of children. Whatever the cause, it is unlikely to be related to the use of the CB. A larger number of patients will be required to clarify this association. Lastly, further long-term follow up is warranted to assess the clinical impact over time of this angioplasty technique. Conclusion Based on this early experience, CBA appears to be a useful adjunctive technique to provide additional luminal gain in selected cases of CoA resistant to conventional balloon angioplasty. A larger randomized trial is indicated to better define the balloon diameter required, as well as the safety and efficacy profile of this technique. _________________________ From the Labatt Family Heart Center, the Cardiac Diagnostic and Interventional Unit, the Hospital for Sick Children, and the University of Toronto School of Medicine, Toronto, Ontario, Canada. The authors report no conflicts of interest regarding the content herein. Manuscript submitted October 31, 2008, provisional acceptance given December 2, 2008, final version accepted February 19, 2009. Address for correspondence: Lee Benson, MD, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G1X8, Canada. E-mail: benson@sickkids.ca

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