Relevance of Pressure Recovery in a Young Patient With Aortic Stenosis and Small-Caliber Aorta

The case concerns a 20-year-old patient with Canadian Cardiovascular Society class II angina who was initially referred for aortic valve replacement because of a suspected high-grade aortic valve stenosis with increased transvalvular gradients (max/mean: 70/40 mm Hg) measured by Doppler echocardiography. Examinations using transesophageal echocardiography and computed tomography showed a sufficiently opening bicuspid aortic valve, excluded supra- and subvalvular stenoses, and measured a narrow aorta (diameter: 2 cm). The explanation for the highly increased gradients across the aortic valve was the pressure recovery (PR) phenomenon, which cannot be detected by Doppler gradients. Distal to a stenosis kinetic energy is converted back into potential energy, most effectively in small aortas (area: <3 cm²). This reduces the actual transvalvular pressure gradient, which can directly be determined with cardiac catheterization. Accordingly, invasive measurements showed a moderate aortic stenosis (mean transvalvular pressure: 19 mm Hg), almost identical to the PR-corrected Doppler measurements. A high-grade stenosis of the proximal left anterior descending artery was treated interventionally, which could explain the angina symptoms.