ESTIMATE PULMONARY ARTERY PRESSURE BY DOPPLER US: AORTOPULMONARY SHUNT

主动脉瘤（AP）分流术通常用于治疗 限制肺血流量的先天性心脏病。 等 程序通常是临时阶段，直到孩子 足够大和稳定，以进行更激进，但治疗 procedure. 治疗性手术的时机对患者的预后至关重要。 孩子的长期生存。 如果手术做得太快， 由于婴儿的体型，死亡率更高。 但如果 手术延迟，不可逆的肺动脉高压可能会 开发 因此，持续评估肺动脉压是 这对这些婴儿的最佳临床分期至关重要。 不幸的是，因为这些婴儿中有许多患有肺动脉闭锁或 重度狭窄，导管法评估肺动脉压 几乎不可能 因此，非侵入性地 估计跨AP分流管的压力梯度（PG）， 用于直接通过从 易于测量的全身压力。 连续波多普勒超声 有时用于估计跨AP分流的PG， 简化伯努利方程（PG=4v2）。 然而，这个等式 我们实验室以前的体外工作表明，由于 分流器上的摩擦损失和远端的压力恢复 分流器 使用FIDAP 7.52，有限元计算流体 动力学软件包可在克雷C90在匹兹堡 超级计算中心，我们希望能够了解 由简化的伯努利方程产生的差异和使用 该知识用于导出更准确的估计技术。 我们 开发了一种三维网格， 该区域将使用稳定和脉动计算网格， 充分描述了该地区，并将使用稳定和脉动 计算使用湍流模型推导的起源和 各种直径的AP分流器上的压降大小， 长度和纵横比（分流直径到肺动脉 直径）。 该提案要求服务单位进行试点 一个更大的建议的数据。

Aortopulmonary (AP) shunts are commonly used in the treatment of congenital heart disease that restricts pulmonary blood flow. Such procedures are usually temporary stages which serve until the child is sufficiently large and stable to undergo a more radical but curative procedure. The timing of the curative surgery is critical to the long-term survival of the child. If the procedure is done too soon, mortality is greater because of the size of the infant. However, if the procedure is delayed, irreversible pulmonary hypertension may have developed. Therefore, continuous assessment of pulmonary pressure is critical for the optimum clinical staging of these infants. Unfortunately, because many of these infants have pulmonary atresia or severe stenosis, evaluation of pulmonary arterial pressure by catheter is nearly impossible. Therefore it is of great value to noninvasively estimate the pressure gradient (PG) across AP shunts, which can be used to calculate pulmonary pressure directly by subtraction from the easily measured systemic pressure. Continuous wave Doppler ultrasound is sometimes used to estimate the PG across AP shunts using the simplified Bernoulli equation (PG=4v2). However, this equation has been shown by previous in vitro work in our lab to be inadequate, due to frictional losses across the shunt and pressure recovery distal to the shunt. Using FIDAP 7.52, a finite element computational fluid dynamics package available on the Cray C90 at the Pittsburgh Supercomputing Center, we hope to gain an understanding of discrepancies produced by the simplified Bernoulli equation and use this knowledge to derive a more accurate estimation technique. We have developed a three dimensional mesh which sufficiently describes the region and will use steady and pulsatile computations mesh which sufficiently describes the region and will use steady and pulsatile computations using a turbulent model to deduce the origin and magnitude of the pressure drop across AP shunts of various diameters, lengths and aspects ratios (shunt diameter to pulmonary artery diameter). This proposal requests service units to generate pilot data for a larger proposal.