Klin Onkol. 2024;37(1):10-19. doi: 10.48095/ccko202410.
Cardiovascular diseases represent the most common non-oncologic cause of death in patients following radiotherapy (RT) in the thoracic region. Radiation-induced heart disease (RIHD) can manifest as various heterogeneous clinical entities. However, the influence of RT on the cardiac conduction system has only recently gained more attention. Arrhythmogenic toxicity, i.e., conduction disorders and arrhythmias, constitutes a significant part of these adverse effects. The cardiac conduction system is not routinely monitored as an organ at risk (OaR). Its specific histological nature and function suggest different sensitivity and response to radiation. The heart is a highly heterogeneous organ, and the routinely monitored dose to the whole heart may not adequately characterize the risk of increased arrhythmogenic toxicity from RT. Cardiac structures, including the conduction system, appear to be additional OaRs for which dose distribution should be monitored.
For the systematic selection of studies, we utilized the PubMed database with keywords derived from the analysis of existing literature. The search was limited to English-language publications, and the selection criteria included relevance to the topic and the quality of methodology.
This article summarizes the impact of RT on the cardiac conduction system.
Radiotherapy-induced cardiotoxicity significantly affects morbidity and mortality. The heart exhibits heterogeneity in terms of radiosensitivity. Certain cardiac subregions in the dose distribution show a higher correlation with poorer overall survival than routinely monitored doses to the whole heart and derived parameters (the volumes irradiated with the doses of 5 or 30 Gy - V5 or V30, respectively). The most radiosensitive subregions appear to be the base of the heart, including the beginning of the conduction system. Higher doses to the conduction system, especially the sinoatrial (SA) node, are associated with a higher incidence of a wide range of arrhythmias and poorer overall survival. However, dose limits (Dmean and Dmax) for the conduction system have not yet been established. Dosimetric studies have identified cutoff doses to the SA node, exceeding which there is a significant increase in mortality and the occurrence of arrhythmias.
心血管疾病是胸部放疗后患者最常见的非肿瘤死亡原因。放射性心脏病（RIHD）可表现为各种异质的临床实体。然而，放射治疗对心脏传导系统的影响最近才引起更多关注。致心律失常毒性，即传导障碍和心律失常，是这些不良反应的重要组成部分。心脏传导系统不作为风险器官（OaR）进行常规监测。其特定的组织学性质和功能表明其对辐射的敏感性和反应不同。心脏是一个高度异质的器官，常规监测的整个心脏剂量可能不能充分描述放射治疗引起的致心律失常毒性增加的风险。心脏结构，包括传导系统，似乎是需要监测剂量分布的其他 OaR。
为了系统地选择研究，我们利用了 PubMed 数据库，并使用现有文献分析得到的关键词。搜索仅限于英文出版物，选择标准包括与主题的相关性和方法的质量。
本文总结了放射治疗对心脏传导系统的影响。
放射治疗诱导的心脏毒性显著影响发病率和死亡率。心脏在放射敏感性方面表现出异质性。剂量分布中某些心脏亚区与总生存率的相关性高于常规监测的整个心脏剂量和衍生参数（分别用 5 或 30Gy 剂量照射的体积-V5 或 V30）。最敏感的亚区似乎是心脏的底部，包括传导系统的起点。传导系统的高剂量，特别是窦房结（SA 结），与广泛的心律失常发生率较高和总生存率较差相关。然而，传导系统的剂量限制（Dmean 和 Dmax）尚未确定。剂量学研究已经确定了 SA 结的临界剂量，超过该剂量，死亡率和心律失常的发生率显著增加。
