Korean J Thorac Cardiovasc Surg.  2004 Jan;37(1):50-55.

Significance of Microembolic Signals during Oxygen Inhalation in Patients with Prosthetic Mechanical Heart Valve

• Cho SJ
• Na CY
• Lee E
• Minn YK
• Kwon KH
• Lee JJ
• Baek MJ
• Oh SS
• Hong SK
• Hwang HK

Abstract

BACKGROUND: Transcranial Doppler ultrasonography (TCD) can detect microembolic signals (MES) in the patients with a potential embolic source. Clinical significance of MES has not been demonstrated in patients with prosthetic mechanical heart valves. We studied the correlation between cerebral thromboemoblic events after the mechanical heart valve surgery (MHVS) and residual MES during TCD monitoring with 100% oxygen inhalation in patients with mechanical heart valves. MATERIAL AND METHOD: Twenty patients with previous cerebral thromboemoblic events after MHVS and a sex- and age-matched control group (n=30) were studied. TCD monitoring was performed from unilateral middle cerebral artery. After baseline monitoring for 20 minutes, 6L of oxygen was inspired for 40 minutes. RESULT: The site of valve and the duration after MHVS of the patients did not differ from those of controls. During baseline monitoring, there was no significant difference in MES prevalence or counts compared to controls. During oxygen inhalation, patients showed a higher MES prevalence (55%, 27.6%, p=0.045) and a more frequent MES counts (p=0.027) compared to controls.
CONCLUSION
TCD monitoring with oxygen inhalation may be useful to differentiate clinically significant MES in patients with mechanical heart valve.

Keyword

Ultrasound; Heart valve prosthesis; Embolism; Oxygen

MeSH Terms

Embolism
Heart Valve Prosthesis
Heart Valves*
Heart*
Humans
Inhalation*
Middle Cerebral Artery
Oxygen*
Prevalence
Ultrasonography
Ultrasonography, Doppler, Transcranial
Oxygen