González-Suárez Ana, Herranz David, Berjano Enrique, Rubio-Guivernau Jose L, Margallo-Balbás Eduardo
Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain.
Medlumics S.L, Tres Cantos, Spain.
Lasers Surg Med. 2018 Mar;50(3):222-229. doi: 10.1002/lsm.22771. Epub 2017 Nov 23.
BACKGROUND/OBJECTIVE: Radiofrequency (RF) catheter ablation is a minimally invasive medical procedure used to thermally destroy the focus of cardiac arrhythmias. Novel optical techniques are now being integrated into RF catheters in order to detect the changes in tissue properties. Loss of birefringence due to fiber denaturation at around 70°C is related to changes in accumulated phase retardation and can be measured by polarization-sensitive optical coherence reflectometry (PS-OCR). Since irreversible thermal lesions are produced when the tissue reaches 50°C, our goal was to seek the mathematical relationship between both isotherms.
A two-dimensional model based on a coupled electric-thermal problem was built and solved using the finite element method. The model consisted of cardiac tissue, blood, and a non-irrigated electrode with a sensor embedded in its tip to maintain a specific target electrode temperature. Computer simulations were conducted by varying the tissue characteristics. Lesion depth was estimated by the 50°C isotherm, while the denaturation time (TD) was taken as the time at which the 70°C isotherm reached a depth of 0.75 mm (which corresponds to the optical depth reached by PS-OCR technology).
A strong correlation (R > 0.83) was found between TD and lesion depth and an even stronger correlation (R > 0.96) was found between TD and the time required to achieve a specific lesion depth. For instance, the ablation time required to ensure a minimum lesion depth of 3 mm was 1.33 × TD + 3.93 × seconds.
The computer results confirmed the strong relationship between denaturation time and lesion depth and suggest that measuring denaturation time by PS-OCR could provide information on the ablation time required to reach a specific lesion depth. Lasers Surg. Med. 50:222-229, 2018. © 2017 Wiley Periodicals, Inc.
背景/目的：射频（RF）导管消融是一种用于热破坏心脏心律失常病灶的微创手术。新型光学技术目前正被集成到射频导管中，以检测组织特性的变化。由于在70°C左右纤维变性导致的双折射丧失与累积相位延迟的变化有关，并且可以通过偏振敏感光学相干反射测量法（PS - OCR）进行测量。由于当组织达到50°C时会产生不可逆的热损伤，我们的目标是寻找这两个等温线之间的数学关系。
建立了一个基于电热耦合问题的二维模型，并使用有限元方法求解。该模型由心脏组织、血液和一个非灌注电极组成，电极尖端嵌入一个传感器以维持特定的目标电极温度。通过改变组织特性进行计算机模拟。损伤深度通过50°C等温线估计，而变性时间（TD）被视为70°C等温线达到0.75毫米深度时的时间（这对应于PS - OCR技术达到的光学深度）。
发现TD与损伤深度之间存在强相关性（R ＞ 0.83），并且在TD与达到特定损伤深度所需的时间之间发现了更强的相关性（R ＞ 0.96）。例如，确保最小损伤深度为3毫米所需的消融时间为1.33×TD + 3.93×秒。
计算机结果证实了变性时间与损伤深度之间的紧密关系，并表明通过PS - OCR测量变性时间可以提供达到特定损伤深度所需消融时间的信息。《激光外科与医学》50:222 - 229, 2018。© 2017威利期刊公司。
