Introduction on Echocardiographic Evaluation of Aortic Stenosis – Normal Flow and Low Flow Scenarios
Aortic stenosis (AS) is a progressive disease of worsening left ventricular outflow obstruction. In the early stage of the disease, the prognosis is excellent with a very small risk of sudden death (<1 % per year).1–3 However, the development of a haemodynamically severe stenosis and the onset of symptoms herald a dramatic deterioration in prognosis. At this point, aortic valve replacement (AVR) provides symptomatic and survival benefits that generally outweigh the associated surgical risks.4–10
Echocardiography plays a critical role in the management of patients with suspected and documented AS by confirming the diagnosis, quantifying the haemodynamic severity and providing prognostic information important for predicting the clinical course and guiding management.9–11 Resting transthoracic echocardiography provides the mainstay technique for these purposes; however, transoesophageal and stress echocardiography can provide additional important information when encountering patients with discordant haemodynamic data, apparently asymptomatic haemodynamically severe AS and severe low-flow, low-gradient AS with or without a reduced left ventricular ejection fraction (LVEF). The purpose of this article is to review the echocardiographic assessment of the AS patient, highlighting important issues related to the assessment of haemodynamic severity, the prediction of clinical outcome and the use of echocardiography to guide patient management in both normal flow and low flow scenarios.