Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine.
Department of Cardiovascular Surgery, Osaka City University.
Magn Reson Med Sci. 2022 Oct 1;21(4):569-582. doi: 10.2463/mrms.mp.2021-0001. Epub 2021 Jul 30.
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.
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.
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 cm. 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 cm, compatible with TTE-EOAs < 1.00 cm, with an excellent prediction of the New York Heart Association classification ≥ III (sensitivity 87.5%, specificity 76.9%).
MRI-EOAs may be an alternative to conventional echocardiography for patients with moderately accelerated AS, especially those with discordant echocardiographic parameters.
在主动脉瓣狭窄（AS）中，中度加速血流与有效瓣口面积（EOA）之间的差异仍然是一个挑战。我们开发了一种使用心脏 MRI 测量收缩期瓣口血流速度的方法，该方法侧重于 AS 患者的中度加速血流，以解决目前只能通过超声心动图来确定 AS 严重程度的问题。
我们对 40 名经胸超声心动图（TTE）峰值跨瓣速度>3.0 m/s 的患者进行了研究。根据峰值跨瓣速度是否≥4.0 m/s，将患者分为高速和中度加速 AS 组。从多层 2D 电影相位对比 MRI 数据中，从重建的 Valsalva 窦射流线上的收缩期瓣口横截面积定义为 MRI-EOAs。通过 TTE 利用连续方程得出患者症状和超声心动图数据，包括 EOA（定义为 TTE-EOA）。
高度加速 AS 组（n=19）的所有患者 MRI 峰值速度均≥4.0 m/s。中度加速 AS 组（n=21）中有 11 名患者的 TTE-EOA<1.00 cm。在中度加速 AS 组中，MRI-EOAs 与 TTE-EOAs 具有很强的相关性（r=0.76，P<0.01）。同时，在高度加速 AS 组中，MRI-EOAs 与 TTE-EOAs 呈正相关，但相关性中等（r=0.63，P=0.004）。MRI-EOAs 比 TTE-EOAs 高估。就中度加速 AS 组而言，MRI-EOAs 的最佳截断值为<1.23 cm，与 TTE-EOAs<1.00 cm 相匹配，对纽约心脏协会分级≥III 的预测效果极佳（灵敏度 87.5%，特异性 76.9%）。
对于中度加速 AS 患者，MRI-EOAs 可能是传统超声心动图的替代方法，尤其是那些超声心动图参数不一致的患者。
