Institut Universitaire de Cardiologie et de Pneumologie de Québec (Québec Heart and Lung Institute), Laval University, Québec, Québec, Canada.
University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada.
JACC Cardiovasc Imaging. 2017 Feb;10(2):185-202. doi: 10.1016/j.jcmg.2017.01.002.
Up to 40% of patients with aortic stenosis (AS) harbor discordant Doppler-echocardiographic findings, the most common of which is the presence of a small aortic valve area (≤1.0 cm) suggesting severe AS, but a low gradient (<40 mm Hg) suggesting nonsevere AS. The purpose of this paper is to present the role of multimodality imaging in the diagnostic and therapeutic management of this challenging entity referred to as low-gradient AS. Doppler-echocardiography is critical to determine the subtype of low-gradient AS: that is, classical low-flow, paradoxical low-flow, or normal-flow. Patients with low-flow, low-gradient AS generally have a worse prognosis compared with patients with high-gradient or with normal-flow, low-gradient AS. Patients with low-gradient AS and evidence of severe AS benefit from aortic valve replacement (AVR). However, confirmation of the presence of severe AS is particularly challenging in these patients and requires a multimodality imaging approach including low-dose dobutamine stress echocardiography and aortic valve calcium scoring by multidetector computed tomography. Transcatheter AVR using a transfemoral approach may be superior to surgical AVR in patients with low-flow, low-gradient AS. Further studies are needed to confirm the best valve replacement procedure and prosthetic valve for each category of low-gradient AS and to identify patients with low-gradient AS in whom AVR is likely to be futile.
高达 40%的主动脉瓣狭窄(AS)患者存在不一致的多普勒超声心动图表现,其中最常见的是存在小主动脉瓣口面积(≤1.0cm)提示严重 AS,但低梯度(<40mmHg)提示非严重 AS。本文旨在介绍多模态影像学在这种被称为低梯度 AS 的具有挑战性实体的诊断和治疗管理中的作用。多普勒超声心动图对于确定低梯度 AS 的亚型至关重要:即经典低流量、矛盾低流量或正常流量。与高梯度或正常流量、低梯度 AS 患者相比,低流量、低梯度 AS 患者的预后通常更差。低梯度 AS 且有严重 AS 证据的患者受益于主动脉瓣置换术(AVR)。然而,在这些患者中,确认严重 AS 的存在特别具有挑战性,需要采用多模态影像学方法,包括低剂量多巴酚丁胺负荷超声心动图和多排螺旋 CT 主动脉瓣钙评分。经股动脉入路的经导管 AVR 可能优于低流量、低梯度 AS 患者的外科 AVR。需要进一步的研究来确定每种低梯度 AS 类别的最佳瓣膜置换术和人工瓣膜,并确定 AVR 可能无效的低梯度 AS 患者。