Is Cerebral Microembolism in Prosthetic Heart Valves Clinically Relevant?
Background. High intensity transient signals (HITS) are frequently detected by TCD ultrasound in patients with mechanical PHV, but the published data about their clinical relevance is controversial. This study was undertaken to determine whether the presence of HITS is related to clinical and neuropsychological changes in patients with mechanical PHV. Methods. Patients with mechanical PHV had bilateral 30 minute TCD monitoring for microemboli (HITS) detection with and without oxygen (O2) inhalation. Cognitive testing of patients included MMSE, DRS, and Microcog with two measures: General Cognitive Performance (GCP) and General Cognitive Functioning (GCF). Results. We studied 36 patients (20 females, mean age 58±13 years), 20 with mitral, 9 with aortic, and 7 with a combined PHV after median of 1.5 years of valve insertion. HITS were detected in 72% of patients. There was no difference in HITS frequency between 16 symptomatic and 20 asymptomatic patients. HITS counts were significantly decreased after O2 inhalation (21.7±30.6 vs. 3.3±9.1 s, p=0.009 ). Table shows that no relationship exists between the number of HITS and cognitive scores of patients. Conclusion. Decreased frequency of HITS after oxygen inhalation confirms their gaseous origin. Lack of relationship between the HITS and cognitive performance suggests that cerebral microembolism in PHV is a benign epiphenomenon without any clinical neurological and neuropsychological sequalae.