Kaushik Atul, Jeewooth Avinash, Jaswal Aparna, Chakravarty Amitesh, Bashir Hamed, Raina Sukriti
Department of Cardiology, Fortis Escorts Heart Institute (FEHI), New Delhi, India.
Department of Cardiac Pacing and Electrophysiology, Fortis Escorts Heart Institute (FEHI), New Delhi, India.
Am J Case Rep. 2024 Dec 20;25:e946186. doi: 10.12659/AJCR.946186.
BACKGROUND Second-degree atrioventricular (AV) block is a frequently encountered conduction abnormality on surface electrocardiogram (ECG). However, it does not always imply a block at the AV nodal level. In rare cases, this block can occur below the bundle of His, within the infra-Hisian region of the His-Purkinje system. While the incidence of infra-Hisian block is generally low in the general population, it becomes more common in specific high-risk groups, such as older adults and individuals with structural heart disease. Infra-Hisian block carries a significant risk of progressing to complete heart block, particularly if the patient shows a markedly prolonged His-ventricular (HV) interval or evidence of a bi-fascicular block. CASE REPORT We present the case of a 65-year-old woman who experienced recurrent episodes of syncope. Her surface ECG revealed a bi-fascicular block along with Wenckebach AV block, and 24-h Holter monitoring showed no other significant abnormalities. A baseline short PR interval with second-degree AV block indicated a possible infra-nodal block. An electrophysiology study confirmed an atypical Wenckebach AV block with second-degree infra-Hisian AV block. The patient subsequently underwent permanent pacemaker implantation. CONCLUSIONS Given its potential to develop into more severe forms of heart block, infra-Hisian block is a critical condition that requires accurate identification and management. Several ECG indicators can help diagnose second-degree AV block. For example, RP-dependent PR interval or RP-PR reciprocity is characteristic of Wenckebach AV block. A short PR interval at baseline and minimal amount of PR interval lengthening before block in type 1 second-degree AV block suggest involvement of the His-Purkinje system.
二度房室传导阻滞是体表心电图（ECG）中常见的传导异常。然而，它并不总是意味着房室结水平的阻滞。在罕见情况下，这种阻滞可发生在希氏束以下，即希氏 - 浦肯野系统的希氏下区域。虽然希氏下阻滞在普通人群中的发生率通常较低，但在特定的高危人群中更为常见，如老年人和患有结构性心脏病的个体。希氏下阻滞进展为完全性心脏阻滞的风险很大，特别是如果患者表现出明显延长的希氏 - 心室（HV）间期或双分支阻滞的证据。
我们报告一例65岁女性反复晕厥发作的病例。她的体表心电图显示双分支阻滞伴文氏房室阻滞，24小时动态心电图监测未发现其他明显异常。基线短PR间期伴二度房室阻滞提示可能为结下阻滞。电生理研究证实为非典型文氏房室阻滞伴二度希氏下房室阻滞。该患者随后接受了永久性起搏器植入。
鉴于希氏下阻滞有可能发展为更严重的心脏阻滞形式，它是一种需要准确识别和管理的关键病症。一些心电图指标有助于诊断二度房室阻滞。例如，RP依赖的PR间期或RP - PR互反性是文氏房室阻滞的特征。1型二度房室阻滞基线短PR间期以及阻滞前PR间期延长量最小提示希氏 - 浦肯野系统受累。
