Objective: To investigate the dynamic change of the secundum atrial septal defect (ASD) throughout the cardiac cycle, and assess its impact on occluder selection. Methods: This study retrospectively analyzed 35 patients with ASD who received electrocardiogram-gated coronary CT angiography (CCTA) throughout the cardiac cycle as well as interventional closure therapy in Fuwai Hospital from December 2016 to December 2019. The raw data were reconstructed into 20 phasic images of RR intervals (RRI) ranging from 0 to 95% in an increment of 5% and transmitted to a workstation for postprocessing. For each phase image, CT virtual endoscopy reconstruction technique (CTVE) was used to provide views of ASD. Axial sequence assisted CT volumetric measurement (CTAS) was used to calculate the maximum dimensions in axial planes (Da) and in superior-inferior direction (Db). Using a formula for converting circumference to diameter, the equivalent circle dimensions were calculated (De, De=minor axis+2 (major axis-minor axis)/3). Taking the data of 75% RRI phase, the patients were divided into Da75%RRI≥Db75%RRI group and Da75%RRI<Db75%RR group. According to the postoperative chest X-ray, the waist diameter of the occluder in the left anterior oblique plain film was measured, and its correction value (CR-PODlaoc) was calculated with the correction formula. Scatter plots of the changes of the mean values of Da, Db and De with the cardiac cycle were presented. The change and ratio of measured values of Da and De at 35% and 75% RRI was calculated. The ratio of De change to Da change in Da75%RRI≥Db75%RRI group and Da75%RRI<Db75%RR group was calculated, respectively, and compared between groups. Pearson correlation analysis was used to explore the correlation between CR-PODlaoc and De35%RRI and De75%RRI. Results: A total of 35 patients, aged (42.7±15.0) years, including 10 males, were included. Among 35 patients, 8 cases were divided into group Da75%RRI≥Db75%RRI and 27 cases into group Da75%RRI<Db75%RRI. Both Da and Db regularly changed at each phase throughout the cardiac cycle. The Da changed significantly, with a maximum at phase of 35%-45% of RRI, and a minimum between phases of 90% and 0 of RRI. While the Db showed insignificant changes during phases of 10%-90% RRI, and increased at 0-10% of RRI, then reduced in the remaining phases. The change of Da was (6.35±2.46) mm, and the ratio of Da values at 35% and 75% RRI was 0.77±0.08. The change of De was (2.28±1.32) mm, and the ratio of De at 35% and 75% RRI was 0.93±0.05. The ratio of De change to Da change in the Da75%RRI≥Db75%RRI group was 0.67±0.13; while the ratio was 0.34±0.05 in Da75%RRI<Db75%RR group, and there was significant difference between the two groups (P=0.02). CR-PODlaoc was positively correlated with De35% RRI (r=0.99, P<0.001) and De75% RRI (r=0.98, P<0.001). Conclusions: Most secundum ASDs show oval shape with Db>Da. Db is basically constant while Da changes significantly during cardiac cycle (10%-90% RRI). Nonetheless, both values peak and maintain the maximum status at end-systolic phase (35%-45% RRI). For patients with huge ASD, occluder selection should be based on the De at 35% RRI phase, which is helpful for the successful intervention.
目的： 探讨继发孔型房间隔缺损（ASD）在心动周期不同时相的动态变化规律及其对封堵器选择的影响。 方法： 本研究为回顾性研究，纳入2016年12月至2019年12月在阜外医院行冠状动脉CT血管成像（CCTA）全心动周期心电门控扫描并成功行介入封堵的ASD患者35例。CCTA影像学数据以5%递增的顺序自0开始依次重建至95%RR间期，合计20个时相。采用CT内镜辅助测量技术（CTVE）观察每个时相的ASD形态，利用CT横断序列辅助测量技术（CTAS）测量出ASD在各时相的横径（Da）及上下径（Db），运用等周长转换公式计算其等效圆直径［De，De=短径+2×（长径-短径）÷3，Da、Db中较大者为长径，较小者为短径］。取75%RR间期时相的数据，将患者分为Da（75%RR间期）≥Db（75%RR间期）组和Da（75%RR间期）<Db（75%RR间期）组。依据术后胸部X线片测量封堵器在左前斜位平片的腰部直径，以校正公式计算得出其校正值（CR-PODlaoc）。绘制Da、Db及De均值随心动周期变化的散点图。分别计算Da、De在35%及75%RR间期时测值的差值（下文简称改变量）及比值。计算Da（75%RR间期）≥Db（75%RR间期）组和Da（75%RR间期）<Db（75%RR间期）组患者的De改变量与Da改变量之比，并进行组间比较。采用Pearson相关分析探讨CR-PODlaoc与De（35%RR间期）及De（75%RR间期）的相关性。 结果： 共纳入35例患者，年龄（42.7±15.0）岁，其中男性10例。Da（75%RR间期）≥Db（75%RR间期）组8例，Da（75%RR间期）<Db（75%RR间期）组27例。散点图显示Da与Db均随心动周期各时相呈规律性变化，Da变化明显，最大值出现在35%~45%RR间期，最小值出现在90%~0 RR间期；Db在10%~90%RR间期无明显改变，在0~10%及90%~0 RR间期先增加后变小。Da的改变量为（6.35±2.46）mm，在35%及75%RR间期时测值的比值为0.77±0.08；De的改变量为（2.28±1.32）mm，在35%及75%RR间期时测值的比值为0.93±0.05。Da（75%RR间期）≥Db（75%RR间期）组的De改变量与Da改变量之比为0.67±0.13；Da（75%RR间期）<Db（75%RR间期）组为0.34±0.05，两组比较差异有统计学意义（P=0.02）。CR-PODlaoc与De（35%RR间期）（r=0.99，P<0.001）、De（75%RR间期）呈正相关（r=0.98，P<0.001）。 结论： 继发孔型ASD多呈横径小于上下径的椭圆形，且二者在心动周期中（10%~90%RR间期）呈现不同的变化规律，横径变化明显，上下径基本保持不变，二者均在收缩期末（35%~45% RR间期）达到并维持最大值。对于缺损巨大的ASD而言，参考35%RR间期时相De选择封堵器是手术成功的最低要求。.