Preoperative quantification of aortic valve stenosis: comparison of 64-slice computed tomography with transesophageal and transthoracic echocardiography and size of implanted prosthesis

Estimating the Haemodynamic Streamline Vena Contracta as the Effective Orifice Area Measured from Reconstructed Multislice Phase-contrast MR Images for Patients with Moderately Accelerated Aortic Stenosis

PURPOSE

In aortic stenosis (AS), the discrepancy between moderately accelerated flow and effective orifice area (EOA) continues to pose a challenge. We developed a method of measuring the vena contracta area as hemodynamic EOA using cardiac MRI focusing on AS patients with a moderately accelerated flow to solve the problem that AS severity can currently be determined only by echocardiography.

METHODS

We investigated 40 patients with a peak transvalvular velocity > 3.0 m/s on transthoracic echocardiography (TTE). The patients were divided into highly accelerated and moderately accelerated AS groups according to whether or not the peak transvalvular velocity was ≥ 4.0 m/s. From the multislice 2D cine phase-contrast MRI data, the cross-sectional area of the vena contracta of the reconstructed streamline in the Valsalva sinus was defined as MRI-EOAs. Patient symptoms and echocardiography data, including EOA (defined as TTE-EOA), were derived from the continuity equation using TTE.

RESULTS

All participants in the highly accelerated AS group (n = 19) showed a peak velocity ≥ 4.0 m/s in MRI. Eleven patients in the moderately accelerated AS group (n = 21) had a TTE-EOA < 1.00 cm². In the moderately accelerated AS group, MRI-EOAs demonstrated a strong correlation with TTE-EOAs (r = 0.76, P < 0.01). Meanwhile, in the highly accelerated AS group, MRI-EOAs demonstrated positivity but a moderate correlation with TTE-EOAs (r = 0.63, P = 0.004). MRI-EOAs were overestimated compared to TTE-EOAs. In terms of the moderately accelerated AS group, the best cut-off value for MRI-EOAs was < 1.23 cm², compatible with TTE-EOAs < 1.00 cm², with an excellent prediction of the New York Heart Association classification ≥ III (sensitivity 87.5%, specificity 76.9%).

CONCLUSION

MRI-EOAs may be an alternative to conventional echocardiography for patients with moderately accelerated AS, especially those with discordant echocardiographic parameters.

Proximal thoracic aortic diameters: transesophageal-echocardiography- versus computed-tomography-derived measurements

PURPOSE

The purpose of the study was to compare proximal aortic measurements from electrocardiogram-gated computed tomography (CT) to transesophageal echocardiography (TEE) and to evaluate differences in cusp-cusp and cusp-commissure CT measurements of sinus of Valsalva (SOV).

METHODS

This retrospective study (n=25) compared aortic diameters from CT using manual double-oblique multiplanar reformats (MPRs) and semiautomatic centerline method to TEE.

RESULTS

CT MPR and centerline measurements were higher than TEE for sinotubular junction and ascending aorta. At SOV, cusp-cusp diameters (MPR and centerline methods) and cusp-commissure measurement (centerline method) were larger than TEE.

CONCLUSIONS

Aortic measurements were larger on CT than TEE. Precise difference depended on location and measurement technique.

Comparison of aortic annulus diameter measurement between multi-detector computed tomography and echocardiography: a meta-analysis

BACKGROUND AND PURPOSE

Accurate measurement of aortic annulus diameter is crucial for choosing suitable prosthetic size for transcatheter aortic valve implantation (TAVI). Several imaging methods are available for the measurement, but significant variability between different modalities has been observed. The purpose of this study was to systematically compare the measurements of aortic annulus diameter between multi-detector computed tomography (MDCT), transthoracic echocardiography (TTE), and transesophegeal echocardiography (TEE).

METHODS

PubMed and EMBASE databases between January 2000 and January 2012 were searched. We extracted data from eligible studies evaluating the aortic annulus diameter by MDCT and echocardiography (TTE, TEE, or both). We performed a random-effects meta-analysis to calculate the weighted mean differences of aortic annulus diameter measurement between MDCT, TTE, and TEE.

RESULTS

A total of 10 eligible studies involving 581 subjects with aortic valve stenosis were included. Aortic annulus diameter measured on coronal view by MDCT (25.3±0.52 mm) was respectively larger than that measured on sagittal view by MDCT (22.7±0.37 mm), TTE (22.6±0.28 mm), and TEE (23.1±0.32 mm). The weighted mean difference of aortic annulus diameter between coronal view by MDCT and TTE these two methods was 2.97 mm, followed by the weighted mean difference of 2.53 mm between coronal view and sagittal view by MDCT, and the mean difference of 1.74 mm between coronal view on MDCT and TEE (P<0.0001 for all). The weighted mean difference of aortic annulus diameter measurement between TEE and TTE was significant but somewhat small (0.45 mm, P = 0.007).

CONCLUSION

Aortic annulus diameter measured on coronal view by MDCT was robustly and significantly larger than that obtained on sagittal view by MDCT, TTE, or TEE. Such variability of aortic annulus diameter measurement by different imaging modalities cannot be ignored when developing optimal strategies for selection of prosthetic valve size in TAVI.

The clinical anatomy and pathology of the human arterial valves: implications for repair or replacement

A thorough understanding of valvar anatomy is essential for design engineers and clinicians in the development and/or employment of improved technologies or therapies for treating valvar pathologies. There are two arterial valves in the human heart--pulmonary and aortic valves. Both are complex structures whose normal anatomical components can vary greatly between individuals. We discuss the anatomy, pathology, and challenges relating to transcatheter and surgical repair/replacement of the arterial valves in a translational manner. The high prevalence of aortic valvar pathologies in the burgeoning elderly population, coupled with poor clinical outcomes for patients who go untreated, has resulted in prolific spending in the research and development of more effective and less traumatic therapies. The accelerated development of therapies for treating arterial valves has been guided by anatomical information gathered from high-resolution imaging technologies, which have focused attention on the need for complete understanding of arterial valvar clinical anatomies. This article is part of a JCTR special issue on Cardiac Anatomy.