Tufts University, Medford, MA, USA.
Cardiovasc Eng Technol. 2022 Oct;13(5):662-672. doi: 10.1007/s13239-021-00607-x. Epub 2022 Feb 1.
Preserved ejection fraction heart failure (HFpEF) can be treated by installing a shunt in the interatrial septum, which relieves excess pressure in the left atrium by allowing blood to flow from left to right. This technique has proven effective in clinical trials, but the details of the flow through the shunted heart are not well understood. The current study aims to collect quantitative data on the relationship between pressure and flow rate in such shunts.
An in vitro, shunted double atrium flow phantom was fabricated and used to investigate the relationship between pressure drop and flow across an interatrial shunt. Flow rate was controlled and the resulting pressure drop across the shunt was measured for a variety of flow cases, including steady and pulsatile flow, flow rate waveforms typical of healthy and failing hearts, and low and high heart rates.
The results show a positive relationship between shunt flow rate and pressure drop which is more pronounced in steady flow than in pulsatile flow. Increasing heart rate increases the time-averaged pressure drop across the shunt but not the maximum pressure drop. For steady-flow cases, large changes in pressure drop resulting from moderate changes in flow rate suggest a flow regime transition during parts of the cardiac cycle. Comparison of time-averaged pulsatile flow pressure measurements with steady-flow measurements and two analytical plate-orifice models suggests that none approximate pulsatile flow accurately.
The flow rate/pressure drop relationship across an in vitro model of an interatrial shunt has been measured for a variety of physiologically relevant cases. Among other things, the results suggest that steady flow approximations to the heart's pulsatile flow should be used with caution and simplified theoretical models do not approximate the flow rate/pressure drop relationship accurately.
通过在房间隔中安装分流器，可以治疗射血分数保留的心力衰竭（HFpEF），从而通过允许血液从左向右流动来减轻左心房的过度压力。该技术已在临床试验中证明有效，但对通过分流心脏的血流细节了解甚少。本研究旨在收集有关此类分流器中压力与流量之间关系的定量数据。
制作了一个体外、分流的双心房流幻影，并用于研究房间隔分流器中的压降与流量之间的关系。控制流量，测量各种流量情况下（包括稳态和脉动流、健康和衰竭心脏的典型流量波形以及低和高心率）通过分流器的压降。
结果表明，分流器流量与压降之间呈正相关，在稳态流中比在脉动流中更为明显。心率增加会增加分流器的平均压降，但不会增加最大压降。对于稳态流情况，流量率的适度变化导致的压降的大变化表明在心脏周期的部分时间内存在流型过渡。稳态流测量与脉动流测量和两个分析板孔模型的比较表明，没有一个能准确地近似脉动流。
已经测量了各种生理相关情况下体外房间隔分流模型的流量/压降关系。除其他外，结果表明，应谨慎使用稳态流对心脏的脉动流的近似值，并且简化的理论模型不能准确地近似流量/压降关系。
