High-intensity transient signals due to prosthetic valve obstruction: diagnostic and therapeutic implications.

Background: High-intensity transient signals (HITS) can be detected by transcranial Doppler ultrasonography (TCD) in patients carrying a mechanical prosthetic valve. The HITS counts and a frequency analysis were evaluated in patients with prosthetic valve obstruction in the aortic position.

Methods: Simultaneous echocardiographic, cineradiographic, and TCD evaluations for a St.