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Balloon Sizing of Pulmonary Branch Stenosis: A Useful Method to Guide Stent Implantation<br />
August 2003
Intravascular stent implantation is the preferred treatment for native and post-operative branch pulmonary stenosis.1–4 The standard procedure for stent placement1 includes calibrated angiography, which has been regarded as the optimal calibration method for size estimation.5 The selection of angioplasty balloon catheter diameters and stents depends upon measurements of the stenosed vessel diameters determined by calibrated angiography. The aim of this technical report was to compare vessel dimensions determined by standard calibrated angiography to those obtained with the use of a compliant sizing balloon catheter. The impact of this comparison on the selection of the angioplasty balloon catheter diameter and stent was determined.
Methods
After informed consent, nine consecutive patients (median age, 10 years; age range, 3–27 years; median weight, 37.7 kg; weight range, 14–106 kg) with 11 pulmonary branch stenoses were included in this study. Each patient underwent standard diagnostic catheterization and calibrated selective angiography of the affected pulmonary vessels. Subsequently, a super-stiff wire was positioned in the distal pulmonary artery and a 24 mm Amplatzer Sizing Balloon Catheter (AGA Medical Corporation, Golden Valley, MN) was passed over the wire until its midpoint was at the stenosis site. The balloon was then inflated with dilute (1:3) contrast agent and angiograms were obtained in the same projections as the calibrated angiograms. A marker pigtail catheter placed in the descending aorta and kept in the same position during both sets of angiograms was used for calibration and measurement of selected diameters from the images digitally stored on our catheterization lab digital system (Philips Integris BH 5000).
The following dimensions were measured in both the standard calibrated and the sizing balloon angiograms: minimum vessel diameter; maximum proximal vessel diameter; maximum distal vessel diameter; distance between the maximal proximal and maximal distal diameters. First, the minimum vessel diameter was determined on both angiograms. Then, the maximum proximal and maximum distal diameters were determined from the sizing balloon angiograms. The distances between the midpoint of the minimum diameter to the midpoints of both the maximum proximal and maximum distal diameters were measured from the sizing balloon angiograms. These distances were used to determine the vessel locations where maximum proximal and maximum distal diameters were measured on the calibrated angiograms. Calibration for measurements in both images was provided by the marker pigtail catheter positioned in the descending thoracic aorta. Figures 1 and 2 show the measurement technique studied in both the sizing balloon and the calibrated angiography methods. Figure 3 shows a selective angiogram after stent implantation. The two sets of measurements were then compared statistically using a paired t-test.
Results
The minimum vessel diameter, maximum proximal vessel diameter and maximum distal vessel diameter were larger when measured with the sizing balloon technique. The differences were statistically significant (p
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