Aortic stenosis: echocardiography, ECG and CT assessment
THE CONTEXT
Investigations establish valve restriction and assess stenosis severity, while accounting for the effects of ventricular function and stroke volume.
Echocardiography and flow-dependent assessment
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Echocardiography is pivotal in suspected aortic stenosis and can demonstrate restricted valve opening. Doppler assessment allows calculation of the systolic gradient across the valve to assess severity.
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Impaired left ventricular function can reduce stroke volume and transvalvular velocities, producing low-flow aortic stenosis.
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Dobutamine stress echocardiography helps distinguish truly severe stenosis from pseudosevere stenosis, where poor left ventricular function causes reduced valve excursion.
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Marked aortic regurgitation or elevated cardiac output increases stroke volume and transvalvular velocities, potentially overestimating stenosis severity on Doppler echocardiography.
Electrocardiographic findings
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Advanced disease often produces pronounced electrocardiographic features of left ventricular hypertrophy.
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Down-sloping ST segments and T-wave inversion in the lateral leads form a strain pattern reflecting left ventricular fibrosis.
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A normal electrocardiogram does not exclude severe aortic stenosis.
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Fibrocalcific encroachment on the adjacent atrioventricular node and His–Purkinje system can cause atrioventricular block, occasionally producing syncope.
Computed tomography
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Computed tomography assessment of valve calcification using a calcium score may help when disease severity remains uncertain.