Rodriguez Rosendo A, Ruel Marc, Labrosse Michel, Mesana Thierry
Department of Surgery, Division of Cardiac Surgery, University of Ottawa Heart Institute, Room H-4403, 40 Ruskin Street, Ottawa, Ontario, K1Y 4W7, Canada.
Interact Cardiovasc Thorac Surg. 2008 Apr;7(2):179-83. doi: 10.1510/icvts.2007.167569. Epub 2007 Dec 3.
The formation and collapse of vapor-filled bubbles near a mechanical heart valve is called cavitation. Such microbubbles are suspected to have strong pro-coagulant effects. Therefore, cavitation may be a contributing factor to the pro-thrombotic effects of mechanical valves. Herein, we systematically review the available evidence linking cavitation and thrombosis. We also critically appraise the potential usefulness of transcranial Doppler and other new non-invasive diagnostic methods to study cavitation and cerebral embolism in mechanical valve patients. Experimental studies indicate that cavitation microbubbles cause platelet aggregation, complement-activation, fibrinolysis, release of tissue-factor, and endothelial damage. Administration of 100% oxygen to mechanical valve patients during transcranial Doppler examination can transiently decrease the counts of Doppler-detected cerebral microemboli compared with room air. This is associated with removal of most circulating gaseous emboli from cavitation. This method may therefore be applied to the study of cavitation and thromboembolism. Additionally, the analysis of high-frequency acoustic-pressure fluctuations detected from the implosion of cavitation bubbles is a promising method for assessment of cavitation in vivo; however, this requires further development. A better understanding of cavitation is important in order to adequately investigate its role in the overall pro-thrombotic effects in mechanical valve patients. Such studies may allow establishing guidelines for new valve designs.
机械心脏瓣膜附近充满蒸汽的气泡的形成与破裂被称为空化现象。这种微气泡被怀疑具有很强的促凝血作用。因此，空化现象可能是机械瓣膜促血栓形成作用的一个促成因素。在此，我们系统地综述了将空化现象与血栓形成联系起来的现有证据。我们还批判性地评估了经颅多普勒及其他新的非侵入性诊断方法在研究机械瓣膜患者的空化现象和脑栓塞方面的潜在用途。实验研究表明，空化微气泡会导致血小板聚集、补体激活、纤维蛋白溶解、组织因子释放以及内皮损伤。在经颅多普勒检查期间，给机械瓣膜患者吸入100%的氧气，与吸入室内空气相比，可使检测到的脑微栓子数量暂时减少。这与清除空化现象产生的大多数循环气态栓子有关。因此，该方法可应用于空化现象和血栓栓塞的研究。此外，分析空化气泡内爆产生的高频声压波动是一种有前景的体内空化现象评估方法；然而，这还需要进一步发展。为了充分研究空化现象在机械瓣膜患者整体促血栓形成作用中的作用，更好地理解空化现象很重要。此类研究可能有助于制定新瓣膜设计的指导原则。
