Department of Cardiac Surgery, Boston Children's Hospital, Boston, Massachusetts.
Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah.
Semin Thorac Cardiovasc Surg. 2019 Autumn;31(3):537-546. doi: 10.1053/j.semtcvs.2019.02.006. Epub 2019 Feb 6.
We performed preclinical validation of intraoperative fiber-optic confocal microscopy (FCM) and assessed its safety and efficacy in an ovine model of the pediatric heart. Intraoperative imaging was performed using an FCM system (Cellvizio, Mauna Kea Technology, Paris, France) with specialized imaging miniprobe (GastroFlex UHD, Mauna Kea Technologies). Before imaging, we applied an extracellular fluorophore, sodium fluorescein, to fluorescently label extracellular space. We imaged arrested hearts of ovine (1-6 months) under cardiopulmonary bypass. Image sequences (1-10 seconds duration) were acquired from regions of the sinoatrial and atrioventricular node, as well as subepicardial and subendocardial working myocardium from atria and ventricle. The surgical process was evaluated for integration of the imaging protocol during the operative procedure. In addition, fluorescein cardiotoxicity studies (n = 3 animals) were conducted by comparing electrocardiogram (PR and QRS intervals) and ejection fraction at baseline and after topical application of fluorescein at 1:10, 1:100, and 1:1000 dilutions on a beating ovine heart. Our studies suggest that intraoperative FCM can be used to identify regions associated with specialized conducting tissue in ovine hearts in situ. The imaging protocol was integrated with conventional open heart surgical procedures with minimal changes to the operative process. Application of fluorescein in varying concentrations did not affect the normalized PR interval, QRS interval, and ejection fraction. These preclinical validation studies demonstrated both safety and efficacy of the proposed intraoperative imaging approach. The studies constitute an important step toward first-in-human clinical trials.
我们对术中光纤共聚焦显微镜（FCM）进行了临床前验证，并在小儿心脏的羊模型中评估了其安全性和有效性。术中成像使用了 FCM 系统（Cellvizio，Mauna Kea Technology，巴黎，法国）和专门的成像微型探头（GastroFlex UHD，Mauna Kea Technologies）。在成像之前，我们应用细胞外荧光染料，荧光素钠，对细胞外空间进行荧光标记。我们对心肺旁路下的羊（1-6 个月）停跳心脏进行成像。从窦房结和房室结区域以及心房和心室的心外膜和心内膜工作心肌采集图像序列（持续 1-10 秒）。评估了手术过程中整合成像方案的情况。此外，通过比较心电图（PR 和 QRS 间隔）和射血分数，在 1:10、1:100 和 1:1000 稀释度的荧光素局部应用于跳动的羊心脏后，进行了荧光素心脏毒性研究（n=3 只动物）。我们的研究表明，术中 FCM 可用于识别与羊心脏原位特殊传导组织相关的区域。该成像方案与常规的心脏直视手术程序相结合，对手术过程的影响最小。应用不同浓度的荧光素不会影响归一化 PR 间隔、QRS 间隔和射血分数。这些临床前验证研究证明了所提出的术中成像方法的安全性和有效性。这些研究是迈向首例人体临床试验的重要一步。
