Williams-Beuren syndrome is a genetic malformation caused by microdeletion at locus 7q11.23 involving 28 genes.1 This region includes the elastin gene which codes for essential components of the arterial extracellular matrix. It gives rise to arterial wall hypertrophy with reduced distensibility. 2 Usually there is widespread pulmonary arterial involvement. Intravascular ultrasound studies have demonstrated severe wall-thickening involving the endothelial, medial and adventitial layers, with secondary luminal narrowing. 2 Asymptomatic pulmonary arterial stenoses associated with subsystemic right ventricular (RV) pressure have a favorable long-term prognosis, with eventual spontaneous growth of the pulmonary arterial bed, and many patients requiring no further intervention. 3 Symptomatic patients with suprasystemic RV pressures, on the other hand, require intervention to prolong life and improve quality of life. Surgical treatment is feasible if the proximal branches are involved, but more peripheral stenoses require percutaneous balloon angioplasty. We report a novel use of the scoring coronary AngioSculpt balloon, AngioSculpt™ (AnisoScore, Inc., Alameda, California) for resistant lesions in a 7-year-old child with Williams-Beuren syndrome. Case 1. A 7-year 5 month-old female patient known to have William-Beuren syndrome had extensive bilateral peripheral branch pulmonary arterial stenoses well beyond the hilar bifurcation with suprasystemic right ventricular pressures. She had only mild supravalve aortic stenosis. She was diagnosed at 4 months with cytogenetics studies demonstrating a microdeletion within the 7q11.23 region. Initial cardiac catheterization at 6 months confirmed extensive and severe branch pulmonary artery stenoses. Repeat cardiac catheterization at 5 years of age showed mild-to-moderate supravalvar aortic stenosis which had not progressed, and near systemic RV pressures (73 mmHg vs. 80 mmHg). Multiple coronary balloon dilatations were carried out using a standard high-pressure 3.5 x 20 mm Maverick OTW balloon (Boston Scientific Corp., Natick Massachusetts) up to 15 mm atmospheres (atm). Dilatation was performed in the left lower lobe (2 segments), the right lower lobe (2 segments) and the right upper lobe (1 segment). The lesions were however distensible with no visible waist and there was no significant change in the RV pressure at the end of the procedure. At age 5 and a half years, her RV had become dilated with an associated moderate degree of hypertrophy. At repeat cardiac catheterization, her RV pressures were 83 mmHg, versus a systemic pressure of 93 mmHg. Attempted balloon angioplasty of the left pulmonary artery with conventional balloon dilatation demonstrated a number of resistant lesions and an inability to overcome the waist. A 3 mm x 10 mm Cutting Balloon (InterVentional Technologies Inc., San Diego, California) was therefore used to obliterate the waist, followed by 4 mm of balloon angioplasty. There was improvement angiographically and the RV pressure had declined to 54 mmHg. At 7 years of age, she presented with exertional intolerance due to dyspnea. Repeat cardiac catheterization was carried out, this time with specific consent to use the AngioSculpt balloon. Her RV pressures were now suprasystemic (74 mmHg vs. 70 mmHg). The peripheral branch pulmonary artery stenoses were widespread, as previously demonstrated (Figures 1 and 2). Dilatations were carried out initially in the distal stenoses in multiple branches on the right and left using 1.5 mm and 3 mm coronary balloons. These lesions were distensible and failed to respond to conventional angioplasty. For the larger interlobar branches, a 6 mm Tyshak® (NuMed, Inc., Denton, Texas) was used in the main upper and lower lobe branches in the right lung and the lower lobe branches on the left. There was, however, a residual discreet waist which could not be overcome with 4 atm of inflation pressure on the left and right sides. The right side the stenosis was complex over a long segment. The residual waist measured 4 mm during standard balloon inflation, and we therefore went on to use an AngioSculpt 5 mm x 2 cm over a standard 0.014 inch Whisper MS (Abbott Vascular, Abbott Park, Illinois) in the right upper and lower lobe branches, as well as in the left lower lobe. Multiple waists demonstrated on the right lower lobe were effectively relieved at 4 atm of pressure. Initially, the balloon milked back into the proximal pulmonary artery during inflation. Angiographically, there was significant luminal improvement in all segments dilated and the RV pressure at the end of the procedure was 65 mmHg versus a systemic pressure of 98 mmHg (Figure 2). Discussion. Resistant pulmonary arterial lesions remain a challenge in the interventional cardiac catheterization laboratory.4 Lesions may be either very distensible, resulting in post-balloon dilatation recoil, or alternatively, they may be resistant to conventional high-pressure distension. Both lesions occur in Williams-Beuren syndrome and may coexist within the same vessel. We report for the first time the use of the AngioSculpt in resistant pulmonary arterial lesions associated with this syndrome. The AngioSculpt balloon is available in sizes ranging from 2–6 mm and varies in length up to 4 cm. The 4 mm and larger balloons can accommodate an 0.018 inch guidewire. The balloons can be passed through a 5 or 6 Fr short sheath, but do not necessarily require a long sheath or guide catheter, as the scoring elements are secured proximally and distally and are unlikely to detach. There are three rectangular-shaped nitinol elements that spiral around a semicompliant balloon. Vessel dilatation is achieved through outward directed forces induced by the expanding balloon on the nitinol elements against the stenosed vessel wall. The forces are distributed across a larger area than conventional cutting balloons and theoretically the incidence of vessel perforation and aneurysm transformation may be reduced. Balloon stability also may be enhanced.5 We chose the scoring balloon, as we anticipated that the patient is likely to require further balloon dilations to rehabilitate her pulmonary arteries, and partly because we had only limited success with previous standard approaches. During inflation, the AngioSculpt milked backwards into the pulsatile and distensible proximal right interlobar branch despite using a relatively conservative balloon to minimal vessel diameter of 1.3. This phenomenon is relatively uncommon in the peripheral vasculature. We believe that the marked proximal pulsatile distension of the pulmonary artery in our patient may have contributed to the relative balloon instability during inflation, particularly against relatively limited support from an 0.014 inch coronary guidewire. The distal lesions in our patients were very flexible. When choosing the appropriate balloon size for such flexible lesions, it is particularly important that vessel diameter be measured during ventricular systole coinciding with maximal distension of the artery. In older patients stent implantation in usually appropriate in this setting. The more proximal interlobar branches in our patient had fixed restrictive lesions that resisted distension even with high pressures. The pulmonary arteries in such lesions are often hypertrophied in all of its layers, leading to its ability to produce strong counter forces.2 Cutting balloons are useful in this setting, improving short- and intermediate-term outcomes.6,7 The currently existing cutting balloons were designed to treat resistant coronary artery disease.8 They consist of a noncompliant balloon and sharp blades or microtomes lying within the folding pleats of deflated balloon. The blades cut the vessel wall to break resistant tissues without requiring high pressure. The balloon diameters range from 2–8 mm with 3–4 microtomes depending on the balloon size.8 Complications of traditional cutting balloon intervention include vessel dissection, rupture, perforation and aneurysm formation in up to 18% of patients, as well as restenosis rates of up to 32%, and failure to dilate a stenosed lesion.8 The balloon can be damaged by the sharp microtomes failing to deflate, particularly if there is undue rotation of the balloon catheter during catheterization. Under such circumstances, the microtomes may embolize when the balloon is retrieved back into the long sheath or guide catheter. We chose a balloon size 1 mm greater than the narrowest luminal diameter demonstrated on conventional balloon inflation. This resulted in effective relief of the stenosis when followed by a conventional, appropriately-sized low-pressure balloon. Conclusions. Treatment of peripheral pulmonary artery stenosis remains a challenge. These patients often need multiple interventions. The potential complications associated with conventional cutting balloons are well understood, and perhaps many of these can be avoided with the endovascular scoring-balloon systems. We propose that use of a scoring angioplasty balloon in the peripheral pulmonary vasculature is a reasonable alternative to blade angioplasty and conventional high-pressure balloons.
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From the Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, United Kingdom. The authors report no conflicts of interest regarding the content herein. Manuscript submitted July 31, 2009, provisional acceptance given August 31, 2009, final version accepted September 14, 2009. Address for correspondence: Gruschen R. Veldtman, MBChB FRCP, Mailpoint 46, Congenital Heart Disease, Southampton University Hospital, Tremona Road, SO 16 6YD United Kingdom. E-mail: email@example.com