Introduction
Transcatheter valve therapies are being increasingly used in the treatment of valvular heart disease. Transcatheter aortic valve replacement (TAVR) has been adopted as an alternative method of treatment for patients with severe aortic stenosis (AS) who are deemed unfit for open valve surgery. Pre and periprocedural imaging is pivotal for accurate valve sizing, deployment and assessing for postprocedural aortic and paravalvular regurgitations and other complications. The valve sizing is one of the most important factors for this procedure to be successful; therefore accurate measurements of the aortic root are needed preprocedure. A variety of imaging techniques,1 including multislice CT (MSCT) has been described as the gold standard to assess aortic root and annulus dimensions preprocedure, two-dimensional (2D) echocardiography, three-dimensional (3D) echocardiography and the use of transesophageal echocardiography (TOE) during the procedure for deployment of the valve. Previous studies1 have demonstrated that 2D TOE tends to underestimate the aortic valve annulus diameter, with a modest correlation between the 2D measurements and the MSCT. Underestimation of the diameters are most likely due to the fact that measurements performed in 2D were at a tangent cut across the aortic root. In fact the aortic root is not completely circular at any point, and the shape of the aortic annulus is more elliptical with a maximum and minimum diameters. Routine 2D measurements of the aortic root or annulus by any of these techniques will depend on the plane and angulation, which will have a significant impact on the selection of the prosthetic valve size to implant. We describe the use of real-time three-dimensional intracardiac echocardiography (RT-3D ICE), AcuNav V catheters for accurate aortic root dimensions in patients undergoing TAVR and compare sizing using this technique against that obtained using MSCT. ICE has been used with added advantage in guiding device closure of interatrial shunts and electrophysiological ablation procedures.2
Case reports
Five patients (3 females) with severe AS underwent TAVR procedure using RT-3DICE using an ACUSON SC2000 2.0v (Siemens Medical Solution), and a 10F AcuNav V catheter (Siemens-Acuson, Inc, Mountain View, California, USA) in addition to preoperative MSCT. Aortic valve measurements obtained using RT-3DICE are MSCT and shown in table 1. Real-time monitoring (figure 1 and see online supplementary video file 1) was performed with an Acunav V (volume mode using a 90 cm, 10-F phased-array) catheter capable of articulating 160° in four directions. A 3D imaging volume size of 22°×90° was acquired at 6–8 MHz frequency. The ICE catheter was inserted via a 12F right femoral vein sheath and placed at the roof of the right atrium anterior to the aortic valve (figures 1 and 2). Three Edwards Sapien XT valves (size 26 mm) were implanted and two Edwards Sapien S3 valves (size 26 mm). There was no procedural or 30 day mortality and no procedure-related complications. All patients had concomitant TOE except one who had a large hiatus hernia primarily to assess the presence and severity of aortic or paravalvular regurgitation. Four of the five patients underwent TAVR implantation via the transfemoral route and one patient via the transaortic route. Aortic annulus and sinus of valsalva diameters were measured using RT-3DICE. An independent radiologist blinded to RT-3DICE and TOE measurements performed the MSCT measurements. Post-TAVR, one patient had mild paravalvular aortic regurgitation and quantification was similar on TOE and RT-3DICE.
The image shows intracardiac echocardiography (ICE) probe in a TAVI procedure. TAVI, transcatheter aortic valve implantation.
Pre-TAVI procedure annular area. 3D-ICE annulus area by planimetry versus MSCT annulus area. TAVI, transcatheter aortic valve implantation; MSCT, multislice CT; 3D-ICE, three-dimensional intracardiac echocardiography.
