Nadareishvili Zurab G, Beletsky Vadim, Black Sandra E, Fremes Stephen E, Freedman Morris, Kurzman David, Leach Larry, Norris John W
Stroke Research Unit, Division of Neurology, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Canada.
J Neuroimaging. 2002 Oct;12(4):310-5. doi: 10.1111/j.1552-6569.2002.tb00138.x.
High-intensity transient signals (HITS) are frequently detected by transcranial Doppler (TCD) ultrasound in patients with mechanical prosthetic heart valves (PHVs), but published data about their clinical relevance are controversial. This study was undertaken to determine the clinical relevance of HITS in patients with mechanical PHVs.
The authors prospectively studied patients with mechanical PHVs using TCD monitoring for microemboli detection with and without O2 inhalation. The cognitive testing of patients included the Mini-Mental State Examination, the Dementia Rating Scale, and MicroCog.
The authors studied 36 patients (20 women, aged 58 +/- 13 years). HITS were detected in 72% of patients, with a nonsignificant increase of HITS rate in the aortic valve group (P = .07). There was no significant difference in HITS rate between asymptomatic and symptomatic patients. In a multiple linear regression model, HITS rate was predicted only by younger age (P = .024). No correlation was found between HITS rate and the cognitive performance of patients. There was a significant decrease in HITS rate after 100% O2 inhalation compared to baseline levels (32.8 +/- 40.2 vs 6.1 +/- 11.3, P = .011). Subgroup analysis in asymptomatic patients confirmed this finding (P = .017), but in symptomatic patients, decreased HITS rate was not statistically significant (P = .18).
Only age was a significant predictor of HITS in patients with mechanical PHVs. The lack of association between HITS, clinical symptoms, and cognitive functioning suggests that most of these signals represent harmless epiphenomena, and only HITS detected after O2 inhalation have any clinical relevance.
经颅多普勒（TCD）超声检查经常在机械人工心脏瓣膜（PHV）患者中检测到高强度瞬态信号（HITS），但关于其临床相关性的已发表数据存在争议。本研究旨在确定HITS在机械PHV患者中的临床相关性。
作者前瞻性地研究了机械PHV患者，使用TCD监测微栓子检测，同时进行或不进行吸氧。患者的认知测试包括简易精神状态检查表、痴呆评定量表和微型认知测试。
作者研究了36例患者（20例女性，年龄58±13岁）。72%的患者检测到HITS，主动脉瓣组HITS率有不显著增加（P = 0.07）。无症状和有症状患者的HITS率无显著差异。在多元线性回归模型中，仅年龄可预测HITS率（P = 0.024）。未发现HITS率与患者认知表现之间存在相关性。与基线水平相比，100%吸氧后HITS率显著降低（32.8±40.2对6.1±11.3，P = 0.011）。无症状患者的亚组分析证实了这一发现（P = 0.017），但在有症状患者中，HITS率降低无统计学意义（P = 0.18）。
在机械PHV患者中，只有年龄是HITS的显著预测因素。HITS、临床症状和认知功能之间缺乏关联表明，这些信号大多代表无害的附带现象，只有吸氧后检测到的HITS具有临床相关性。
