Transballoon intravascular ultrasound imaging during balloon angioplasty in animal models with coarctation and branch pulmonary stenosis

Background: Intravascular ultrasound (IVUS) studies performed after balloon dilation provide a method for evaluating the adequacy of angioplasty and the nature of associated changes in vessel walls. Previously, IVUS studies required the use of separate scanning catheters inserted independently before and after balloon angioplasty. We tested a 0.035-in, 30- MHz IVUS transducer wire that images from within commercially available 5F balloon dilation catheters. Methods and Results: Seven stenoses were created in the left pulmonary artery (n=3) and in the aortic isthmus (n=4) in six lambs (weight, 3,4 to 12.5 kg). The balloon catheter selected was advanced across the stenotic area and the IVUS wire advanced in the guide lumen to the center of the balloon. Continuous IVUS images were obtained through balloons before, during, and after dilation. Transballoon imaging confirmed balloon location within the stenotic segment. Luminal diameters of stenotic and adjacent vessel segments before and after angioplasty by IVUS showed good correlation with angiographic measurements (r=.93, P≤.001). After successful dilation, imaging during deflation allowed the assessment of vascular elastic recoil, mural dissection, and luminal size without requiring changes in balloon position. Repeat dilation could be undertaken and the inflation pressure and technique modified on the basis of the observed results. Conclusions: This transballoon IVUS system provides important on-line information about lumen diameter and wall structure for evaluation of angioplasty without the need for catheter changes, providing a method to possibly reduce the likelihood of excessive wall damage and to potentially reduce the number of angiograms required to accomplish and confirm results.