Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany.
Department of Cardiology, Universität zu Lübeck, Lübeck, Germany.
Eur J Cardiothorac Surg. 2022 Jun 15;62(1). doi: 10.1093/ejcts/ezab352.
This is a comprehensive analysis of haemodynamics after valve-sparing aortic root replacement (VSARR) with anatomically curved prosthesis (CP) compared to straight prosthesis (SP) and age-matched volunteers (VOL) using 4D flow MRI (time-resolved three-dimensional magnetic resonance phase-contrast imaging).
Nine patients with 90° CP, nine patients with SP, and twelve VOL were examined with 4D flow MRI. Analyses included various characteristic anatomical, qualitative and quantitative haemodynamic parameters.
Grading of secondary flow patterns was lower in CP patients than in SP patients (P = 0.09) and more comparable to VOL, albeit not reaching statistical significance. However, it was easy to differentiate between VSARR patients and healthy volunteers: Patients more often had angular aortic arches (CP: 89%, SP: 100%; VOL: 17%; P ≤ 0.002), increased average curvature (CP: 0.17/cm [0.15, 0.18]; SP: 0.15/cm [0.14, 0.16]; VOL: 0.14/cm [0.13, 0.16]; P ≤ 0.007; values given as median [interquartile range]), and more secondary flow patterns (CP: 3 [2, 4] SP: 3 [2, 3] VOL: 2 [1, 2]; P < 0.01). Maximum circulation (CP: 142.7 cm2/s [116.1, 187.3]; SP: 101.8 cm2/s [77.7, 132.5]; VOL: 42.8cm2/s [39.3, 65.6]; P ≤ 0.002), maximum helicity density (CP: 9.6 m/s2 [9.3, 23.9]; SP: 9.7 m/s2 [8.6, 12.5]; VOL 4.9 m/s2 [4.2, 7.7]; P ≤ 0.007), and wall shear stress gradient (e.g., proximal ascending aorta CP: 0.97 N/m2 [0.54, 1.07]; SP: 1.08 N/m2 [0.74, 1.24]; VOL: 0.41 N/m2 [0.32, 0.60]; P ≤ 0.01) were increased in patients. One CP patient had a round aortic arch with physiological haemodynamic parameters.
The restoration of physiological aortic configuration and haemodynamics was not fully achieved with the curved prostheses in our study cohort. However, there was a tendency towards improved haemodynamic conditions in the patients with curved prostheses overall but without statistical significance. A single patient with a CP and near-physiological configuration of the thoracic aorta underlines the importance of optimizing postoperative geometric conditions for allowing for physiological haemodynamics and cardiovascular energetics after VSARR.
本研究旨在使用 4D 流 MRI（时相对比磁共振三维成像）对保留主动脉瓣的主动脉根部置换术后（VSARR）采用解剖学曲度人工血管（CP）与直型人工血管（SP）的血流动力学进行全面分析，并与年龄匹配的志愿者（VOL）进行比较。
对 9 例 CP 患者、9 例 SP 患者和 12 例 VOL 进行了 4D 流 MRI 检查。分析包括各种特征解剖、定性和定量血流动力学参数。
CP 患者的次级血流模式分级低于 SP 患者（P=0.09），与 VOL 更相似，但无统计学意义。然而，VSARR 患者与健康志愿者之间很容易区分：患者的主动脉弓更常呈角状（CP：89%，SP：100%；VOL：17%；P≤0.002），平均曲率增加（CP：0.17/cm [0.15，0.18]；SP：0.15/cm [0.14，0.16]；VOL：0.14/cm [0.13，0.16]；P≤0.007；中位数[四分位间距]），且次级血流模式更多（CP：3 [2，4] SP：3 [2，3] VOL：2 [1，2]；P<0.01）。最大循环（CP：142.7 cm2/s [116.1，187.3]；SP：101.8 cm2/s [77.7，132.5]；VOL：42.8cm2/s [39.3，65.6]；P≤0.002）、最大螺旋密度（CP：9.6 m/s2 [9.3，23.9]；SP：9.7 m/s2 [8.6，12.5]；VOL 4.9 m/s2 [4.2，7.7]；P≤0.007）和壁面切应力梯度（例如，升主动脉近端 CP：0.97 N/m2 [0.54，1.07]；SP：1.08 N/m2 [0.74，1.24]；VOL：0.41 N/m2 [0.32，0.60]；P≤0.01）在患者中增加。1 例 CP 患者的主动脉弓呈圆形，血流动力学参数呈生理性。
在我们的研究队列中，采用曲型人工血管并未完全恢复生理性主动脉结构和血流动力学。然而，总体上使用曲型人工血管的患者有改善血流动力学状况的趋势，但无统计学意义。1 例 CP 患者的胸主动脉具有近乎生理性的解剖结构，这突显了优化术后几何条件对于允许 VSARR 后生理性血流动力学和心血管能量的重要性。
