Making sense of highly-disturbed blood flow dynamics

理解高度扰动的血流动力学

• 批准号: RGPIN-2018-04649
• 负责人: Steinman, David
• 金额: $ 4.66万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665910
• 关键词: Making; sense; highly; disturbed; blood

The way blood flows in the body (hemodynamics) is widely thought to have a big impact on vascular diseases like atherosclerosis and aneurysms, the leading causes of heart attacks and strokes. Unfortunately, the complex hemodynamics associated with these diseases are difficult to measure directly, which has led to increasing use of computer simulations of blood flow tied to medical images of the patient, something we call image-based computational fluid dynamics (CFD).******In the last five years my team and I have uncovered strong evidence that hemodynamics may be more complex that many doctors and engineers think. Textbooks tell us that blood flow is mostly orderly (laminar), and only rarely chaotic (turbulent), which has allowed us to take convenient shortcuts to speed up CFD simulations. By not taking these shortcuts, we have found that high-frequency flow fluctuations can arise during parts of the heartbeat, and may or may not look the same in the next beat. While turbulent blood flow is known to aggravate the cells that make up vessel walls and blood, it remains unclear whether these not-quite-turbulent pulsatile flows, which we term “highly disturbed”, are equally troublesome. To understand that, we must first shed some light on the nature of these flows, which are not well studied because they fall between the laminar and turbulent flows that engineers usually deal with. This is the main goal of my proposed NSERC Discovery research.******First, we will figure out how to visualize these highly time-varying, three-dimensional (so, four dimensional) flows, and to quantify their relative complexity. Because we expect these flows to be so visually complicated, we will also use sound to take advantage of humans' ability to discriminate frequencies better by ear than by eye. Second, because highly-disturbed flows are likely to be sensitive to uncertainties in the patient data that drives image-based CFD, we will use clever techniques to determine just how confident we can be in our CFD predictions. Third, because the shape of blood vessels plays a major role in determining the hemodynamics within, we will see if, in light of those uncertainties, we can predict with at least the same confidence the likelihood of highly disturbed blood flow from vessel shape alone, potentially avoiding the need for CFD in the clinic.******This basic engineering research will be carried out in parallel to my clinical research with Toronto Western Hospital on hemodynamic factors for predicting brain aneurysm rupture, providing us with the wide variety of patient data needed to meet our objectives. Ultimately, the knowledge we gain will have application to other cardiovascular diseases where highly-disturbed flows are now also being uncovered, and will provide doctors and engineers with clearer guidelines on how to adequately simulate and/or anticipate them.

人们普遍认为，体内血液流动（血液动力学）的方式对血管疾病和动脉瘤（动脉瘤）（心脏病发作和中风的主要原因）产生了很大的影响。不幸的是，与这些疾病相关的复杂血流动力学很难直接测量，这导致使用与患者医学图像相关的血液流动的计算机模拟，我们称之为基于图像的计算流体动力学（CFD）。教科书告诉我们，血流大部分是有序的（层流），只有很少的混乱（湍流），这使我们能够采取方便的快捷方式来加快CFD模拟。通过不采用这些快捷方式，我们发现在心跳部分中可能会出现高频流动波动，并且在下一次节拍中可能看起来也可能不会看起来相同。虽然已知湍流会加剧构成容器壁和血液的细胞，但尚不清楚这些非扰动的脉动流（我们称为高度受影响的）是否同样麻烦。要理解，我们必须首先阐明这些流的性质，这些流量没有得到很好的研究，因为它们落在工程师通常处理的层流和湍流之间。这是我提出的NSERC发现研究的主要目标。因为我们期望这些流程在视觉上如此复杂，所以我们还将使用声音来利用人类早期比眼睛更好地区分频率的能力。其次，由于受到高度扰动的流程可能对驱动基于图像的CFD的患者数据中的不确定性敏感，因此我们将使用巧妙的技术来确定我们对CFD预测的自信程度。第三，因为血管的形状在确定内部血液动力学方面起着重要作用，我们将看看，根据这些不确定性，我们可以至少具有相同的信心来预测单独使用血管形状高度干扰血液流量的血液流动的可能性，这可能会避免我在临床上进行临床研究的临床研究。动脉瘤破裂，为我们提供满足我们目标所需的各种患者数据。最终，我们获得的知识将应用于其他心血管疾病，这些心血管疾病现在也被发现了，并且将为医生和工程师提供有关如何充分模拟和/或预期的更清晰的指导方针。