Origin and appearance of HITS induced by prosthetic heart valves: an in vitro study.

Patients with mechanical heart valve prostheses show significantly enhanced numbers of HITS detected by transcranial Doppler ultrasound. In order to assess the origin of HITS formation, an in vitro study was set out to quantify valve induced microemboli for mechanical and bioprosthetic valves under various circulatory conditions by means of Ultrasound-Doppler-Sonography. At the same time the influence of CO2 partial pressure on HITS rate vas investigated.