case_images: PMC10875040_01
case_images: (A) Ventricular tachycardia. (B) Advanced AVB.
case_images: fcvm-11-1336609-g001.jpg
case_images: PMC10875040_01_fcvm-11-1336609-g001.jpg
case_images: F1
case_images: His initial ECG in ED showed ventricular tachycardia with heart rate at 130 beats/min (Figure 1A). Rhythm monitoring and repeat ECG showed advanced AVB with ventricular escape and the HR was 20-50 beats/min during syncope (Figure 1B).
case_images: (A) Hematoxylin-eosin staining: infiltration of mononuclear cells between myocytes. (B) Immunohistochemical staining of CD4: white arrow. (C) Immunohistochemical staining of CD68: white arrow. (D) Immunohistochemical staining of CD20: white arrow.
case_images: fcvm-11-1336609-g002.jpg
case_images: PMC10875040_01_fcvm-11-1336609-g002.jpg
case_images: F2
case_images: Muscle biopsy was performed and showed infiltration of CD4+, CD20+ and CD68+ cells in necrosis areas with up-regulation of major histocompatibility complex antigens (MHC) class I in myolemma which indicated an immune-induced myositis (Figure 2).
case_images: (A) Second-degree type I AVB (B) and (C) EPS at baseline. A, atrial potential; CS, coronary sinus; H, his bundle potential; RV, right ventricle; V, ventricular potential (D) and (E) EPS during RA pacing. A, atrial potential; CS, coronary sinus; H, his bundle potential; RV, right ventricle; V, ventricular potential. (F) First-degree AVB and CRBBB.
case_images: fcvm-11-1336609-g003.jpg
case_images: PMC10875040_01_fcvm-11-1336609-g003.jpg
case_images: F3
case_images: I AVB (Figure 3A) 1 month after implantation of the active fixation lead and externalized generator. Invasive EPS was conducted to demonstrated the conductive abilities. EPS, a coronary sinus catheter was placed via femoral vein to record atrial potential and a His bundle catheter was placed to record atrial potential, His potential and right ventricular potential. EPS at baseline showed a surface ECG rhythm of second-degree type I AVB with sinus rhythm and 3:2 AV conduction and AH interval was prolonged from 106 ms to 172 ms with a consistent HV interval of 81 ms (Figures 3B,C). During RA pacing at a cycle length of 600 ms, AH interval was prolonged from 141 ms to 169 ms with an unchanged HV interval of 85 ms (Figures 3D,E). CRBBB (Figure 3F).