Imaging adult patients with discrete subvalvar aortic stenosis

Abstract

Purpose of review Distinction between discrete subvalvar aortic stenosis and other causes of left ventricular outflow obstruction has important implications for predicting natural history and guiding the timing and type of intervention. Imaging, primarily transthoracic echocardiography, plays a pivotal role in the diagnosis and management of adults with subvalvar stenosis. Recent findings The majority of systematic research on imaging of subvalvar aortic stenosis has focused on echocardiography. Transthoracic echocardiography, especially two-dimensional imaging with color and spectral Doppler, remains the main modality for delineation of the anatomic and hemodynamic features of subvalvar stenosis, associated anomalies, and involvement of accessory mitral valve attachments to the subaortic septum or abnormally placed papillary muscles. Transesophageal echocardiography may provide a more detailed definition of left ventricular outflow tract anatomy, including the presence and extension of the obstructive subaortic fibroelastic tissue onto the aortic or mitral valve, especially in patients with poor transthoracic windows. The clinical role for advanced imaging technologies, including 3-dimensional echocardiography, cardiac magnetic resonance, and computed tomography, is evolving but, largely because of the adequacy of established imaging with transthoracic echocardiography, remains relatively limited. Summary In the absence of other congenital heart defects or alternative indications (e.g., coronary angiography), transthoracic echocardiography is usually adequate for assessment of discrete subvalvar aortic stenosis in the adult. In specific clinical situations, supplemental imaging modalities can play an integral role in clinical decision making.

Discrete Subaortic Stenosis: Perspective Roadmap to a Complex Disease

“…Clinical studies and case reports have used transthoracic and transesophageal echocardiography to characterize deranged flow patterns, supporting a role for hemodynamics in the pathogenesis of DSS ( 4 , 14 , 16 , 25 , 41 , 42 ). Preoperative flow characteristics in DSS patients include high mean and peak LVOT gradients, marked subaortic acceleration, and transition to turbulence ( 42 , 43 ).…”

“…Clinical studies and case reports have used transthoracic and transesophageal echocardiography to characterize deranged flow patterns, supporting a role for hemodynamics in the pathogenesis of DSS ( 4 , 14 , 16 , 25 , 41 , 42 ). Preoperative flow characteristics in DSS patients include high mean and peak LVOT gradients, marked subaortic acceleration, and transition to turbulence ( 42 , 43 ). While resection results in a decrease in LVOT pressure gradient ( 4 , 14 , 16 , 25 ), long-term follow-up assessments have evidenced a progressive linear increase in peak LVOT gradient over time ( 4 ).…”

“…Echocardiography has evidenced the existence of global LV flow alterations in DSS patients pre- and post-resection ( 4 , 14 , 16 , 25 , 41 , 42 ). Although this modality provides sufficient information for diagnostics and retrospective analysis, it is unable to capture the local flow characteristics due to its limited temporal and spatial resolutions.…”

Impact of Aortoseptal Angle Abnormalities and Discrete Subaortic Stenosis on Left-Ventricular Outflow Tract Hemodynamics: Preliminary Computational Assessment

“…First, the DSS lesion resulted in stenotic conditions upstream of the aortic valve, marked by a net increase in LVOT flow velocity and skewness, which contribute to flow instability and the emergence of fluctuating velocity components. Those characteristics, which result from the redirection of the flow around the lesion and the formation of a jet-like structure in the LVOT, have been documented in color Doppler echocardiography studies (Aboulhosn and Child, 2006;Opotowsky et al, 2017). Importantly, the present study reveals that those flow characteristics result in an effective degree of stenosis in DSS that is larger than that due to the physical occlusion imposed by the lesion (45% reduction in effective luminal diameter at the vena contracta vs. 25% at the tip of the lesion).…”

Echocardiographic Diagnosis of a Subaortic Membrane Attached to the Free Edge of the Right Coronary Cusp of the Aortic Valve

“…If additional information is needed, cardiac magnetic resonance imaging, computed tomography, and cine angiography may also play a role. 7 There are several different types of subaortic membranes: (1) thin fibrous membrane, (2) thick funnel-shaped fibrotic funnel ring, (3) irregular fibromuscular tissue, and (4) long tunnel type. 8 Patients with tunnel-type membranes and those with LVOTobstruction at multiple levels tend to have a worse prognosis in terms of risk for recurrence and reoperation.…”