Aortic annulus and root measurements in patients undergoing transcatheteraortic valve replacement (TAVR) using three-dimensional rotational angiography (C-arm CT).

Posted On 2012-06-29 11:18:13

Two recent manuscripts in the International Journal of Cardiovascular Imaging (http://www.springerlink.com/content/12287v4334017346/) report data about the use of rotational angiography (1) in the context of TAVR.

Lehmkuhl et al.(2) comparemeasurements of the aortic annulus and root between conventional multi-detector computed tomography (MDCT) and three-dimensional rotational angiography (RA).

In twenty-seven patients (82 ± 11 years) with severe aortic stenosis the aortic annulus, the distance to the coronary ostia, and diameters of the aortic root and the thoracic aorta were measured with both methods by two blinded observers. Linear regression and Bland-Altman analysis were performed to determine the degree of compliance between both methods. The limits of agreement were within two standard deviations for all measurements and with high correlation especially for the supra-annular dimensions. Sizing of the aortic annulus revealed lower interobserver variability for MDCT than for RA with a maximum deviation of 2.1 ± 2.5 and 1.7 ± 2.8 mm for diameter measurements and for the effective diameter, respectively.

The authors conclude that with current protocols intra-procedural RA provides good image quality especially for structures above the aortic annulus. However, due to a lower interobserver variability in sizing the aortic annulus MDCT remains more suitable for aortic root assessment prior to TAVR.

In a second manuscript, Numburi et al. (2)examine the optimal C-arm computed tomography protocol for TAVR in an animal model. In 6 swine, C-arm CT was performed using different un-gated and gated acquisition during sinus rhythm or rapid ventricular pacing. Aortic root enhancement, presence of artifacts and contrast volumes were compared for all methods. Aortic root measurements were compared between C-arm CT and MDCT. Un-gated C-arm CT required less contrast than ECG-gated C-arm CT. Un-gated C-arm CT during rapid pacing with aortic root injection was optimal yielding images with high attenuation, few artifacts, and root measurements similar to MDCT using minimal contrast (36 mL). Predicted angiographic projections were similar to MDCT.

The authors conclude that ungated C-arm CT during rapid pacing with aortic root injection required minimal contrast, yielded high attenuation and few artifacts, and aortic root measurements and predicted angiographic planes similar to those from MDCT.

References:
1.  Kempfert J, Falk V, Schuler G, Linke A, Merk D, Mohr FW, Walther T.Dyna-CT during minimally invasive off-pump transapical aortic valve implantation.Ann Thorac Surg. 2009;88:2041.
2. Lehmkuhl LH, von Aspern K, Foldyna B, Grothoff M, Nitzsche S, Kempfert J, Rastan A, Linke A, Mohr FW, Noettling A, Walther T, Gutberlet M. Comparison of aortic root measurements in patients undergoing transapical aortic valve implantation (TA-AVI) using three-dimensional rotationalangiography (3D-RA) and multislice computed tomography (MSCT): differences and variability.Int J Cardiovasc Imaging. 2012 Jun 19. [Epub ahead of print]
3. Numburi UD, Kapadia SR, Schoenhagen P, Tuzcu EM, von Roden M, Halliburton SS. Optimization of acquisition and contrast injection protocol for C-arm CT imaging in transcatheter aortic valve implantation: initial experience in a swine model.Int J Cardiovasc Imaging. 2012 Jun 20. [Epub ahead of print]