Frontiers in Cardiovascular Medicine ( IF 3.6 ) Pub Date : 2021-12-02 , DOI: 10.3389/fcvm.2021.742297 Yogamaya Mantha 1 , Shutaro Futami 2 , Shohei Moriyama 2 , Michinari Hieda 2
The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.
中文翻译:
重度主动脉瓣狭窄患者风险分层的瓣膜动脉阻抗和无量纲指数
主动脉瓣狭窄 (AS) 的血流动力学影响包括左心室 (LV) 后负荷增加、心肌顺应性降低和心肌负荷增加。AS 患者的 LV 面临双重负荷:瓣膜和动脉负荷。因此,除了跨瓣压差和主动脉瓣面积 (AVA) 之外,AS 中症状的存在和不良事件的发生应该与计算 LV 面临的整体负担更好地相关联。瓣膜动脉阻抗 (Zva) 是一个有用的参数,它提供了对由瓣膜和血管负荷总和产生的整体 LV 血流动力学负荷的估计。除了计算整体 LV 后负荷外,准确估计狭窄严重程度也很重要。在临床实践中,LV 射血分数保留的低流量低梯度 (LF-LG) 重度 AS 的管理需要仔细确认狭窄的严重程度。除了 Zva,无量纲指数 (DI) 是一个非常有用的参数,可将有效瓣膜面积的大小表示为左心室出口道速度-时间积分 (LVOT-VTI) 截面积的比例到主动脉瓣射流的速度(无量纲速度比)。DI 是通过脉冲波多普勒 (LVOT-VTI) 获得的瓣膜下速度除以连续波多普勒穿过主动脉瓣 (AV-VTI) 获得的最大速度的比值来计算的。与 AVA 测量相反,DI 不需要计算 LVOT 横截面积,这是导致错误评估和低估 AVA 的主要原因。因此,在 LG 重度 AS 和 LV 射血分数保留的患者中,在常规超声心动图实践中计算 DI 可能有助于识别可能从主动脉瓣置换术中获益的死亡风险较高的患者亚组。本文旨在阐明不同临床情况下的 Zva 和 DI,与 AS 严重程度、LV 几何形状和功能等标准指标相关联,从而证明可以改善严重 AS 患者的风险分层和临床决策。