EFFECT OF OXYGEN INHALATION ON MICROEMBOLIC SIGNALS IN PATIENTS WITH MECHANICAL AORTIC VALVE

• Main Author: K. Ghandehari Z. Izadimoud
• Format: Article
• Language: English
• Published: Tehran University of Medical Sciences 2005-06-01
• Series: Acta Medica Iranica
• Subjects: Embolism; mechanical valve; oxygen
• Online Access: https://acta.tums.ac.ir/index.php/acta/article/view/2996
• ISSN: 0044-6025; 1735-9694

Microembolic signals (MES) are frequently observed in transcranial ‎Doppler (TCD) recordings of patients with mechanical heart valve (MHV). If gaseous bubbles are the underlying cause, number of MES produced by MHV could be reduced with oxygen ‎inhalation. From September 2003 to September ‎2004, a consecutive series of 14 patients ‎with St Jude aortic valve visited in the cardiology clinic were referred to ‎neurosonology unit, Valie Asr Hospital, Khorasan. TCD monitoring of MES was performed with an ultrasound device and a 2 MHz probe. The MES counts were recorded during 30 ‎minutes breathing room air and thereafter 30 minutes breathing through a facial mask ‎with reservoir bag (6 liter O2 per minute). The criteria of MES detection were ‎characteristic chirping sound, unidirectional signal, random appearance within cardiac ‎cycle and intensity increase ≥ 3dB above background. The MES counts in two periods ‎of monitoring were compared with paired t test and significance was declared at P ‎< 0.05. Twelve patients (8 females and 4 males) were investigated. Oxygen ventilation ‎caused a significant decrease of MES counts in the patients in comparison to breathing ‎room air (P = 0.001). It seems that MES in patients with MHV are mainly gaseous bubbles ‎caused by blood agitation with MHV. The quantity of MES in patients with MHV is ‎not related to the risk of thromboembolic complications in these patients.