复杂血管内装置的脉动耐久性测试

Pulsatile durability testing is performed to evaluate an intravascular device’s resistance to fatigue failure.

Intravascular devices are typically placed within straight mock arteries for testing, mounted onto a stent/graft tester and subjected to cyclical pressure pulses. The pulses create a dynamic radial strain in the mock artery that simulates in vivo strain levels that occur due to the expansion and contraction of the surrounding vessel.

Complex intravascular devices

While many device designs are tested using straight vessels, complex device geometries occasionally require the development of custom mock arteries to simulate target deployment sites. If custom mock vessels are introduced, additional validation and feasibility testing are required.

这种装置的实例包括左心房阑尾封闭剂，以防止非瓣膜心房颤动患者中风，用于复杂脑动脉瘤的神经血管栓塞线圈，腹主动脉瘤的腹血管动脉瘤修复装置，以及用于动脉瘘的装置。

Custom mock artery test apparatus

MDT（现在的元件）设计了电磁炉9100系列支架/移植式测试仪专门用于脉动耐用性测试。其双电机设计非常适合定制应用，因为它允许调整其中一个电机的放大器，以获得更均匀的菌株和改善较大血管长度的应变分布，包括腹主动脉瘤（AAA）器件。单个电机支架测试人员缺乏这种能力。

电磁9100仪器具有4至12个模拟动脉，安装在一对歧管和线性电动机驱动的泵之间。计算机控制系统在受控温度条件下向血管内装置提供径向菌株，并且激光千分镜在各个装置的长度下测量各个位置的径向应变，以确保在整个测试中满足所需的应变水平。

歧管是模块化的并且允许安装模拟容器和直径的定制以匹配每个申请，例如下面所示的神经血管线圈测试（左图像）。

下面的设置（右图像）用于在等渗盐溶液中以40Hz和37±2°C的8个左心房阑尾封堵器（两个每个驻地）的脉动疲劳试验。每次ASTM F2477-07（2013）和ISO 25539-1：2003 / AMD1：2005（现已纳入ISO 25539-1：2017）进行测试。模拟硅胶容器具有两个段，较小的直径部分和升压较大直径部分，以适应封堵器几何形状。

血管内装置脉动耐久性测试的步骤

The table below outlines the main steps of a standard experimental protocol. If custom mock vessels are introduced, additional validation and occasionally feasibility testing take place to ensure that devices are reaching target strain levels.

1. 检查测试船舶和文件观察
2. Perform vessel conditioning on the pulsatile test system
3. 将设备部署到测试船舶中
4. Inspect devices and document observations
5. Install deployed vessels onto the pulsatile test system
6. 用盐水或蒸馏水填充脉动测试系统，并控制温度至37°C
7. 开始循环并调节平均压力以实现血管直径目标
8. Adjust volumetric displacement or ΔP to achieve the strain target
9. 一旦达到目标，开始疲劳试验
10. Monitor the test daily for target compliance and stability
11. 根据测试协议检查Interim TimePoints的设备

Designing the right mock arteries

Design requirements for the custom mock vessels are typically obtained from published data in the literature and/or finite element analysis. The two main outputs are vessel geometry and compliance. To simulate physiological vessel compliance, these mock models are often manufactured from silicone as shown below.

验证测试侧重于应变和合规性目标。在某些应用中，达到目标应变水平比船舶合规更重要。但是，合规性目标在生理建模应用中至关重要。

激光千分尺用于通过沿着定制嘲笑动脉映射菌株来测量应变验证，并使仪器调节直到达到目标值。类似地，通过使用激光仪器的外径测量并将这些值转换为内径来验证目标血管顺应性。校准的压力传感器测量压力水平，并且按照下面的等式计算顺应性：

In summary, complex device geometries and deployment sites often require the development of custom mock arteries. This complexity added to the test setup requires additional validation to ensure that devices are subject to the desired test conditions.

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