Progressive external ophthalmoplegia, retinitis pigmentosa, and cardiac conduction block characterize Kearns-Sayre syndrome（KSS）, a disease with a poor prognosis. We report the case of a 27-year-old man with KSS. He had an ECG at 19 yrs of age and experienced narrowly defined alternating bundle branch block. It initially showed sinus rhythm, left axis deviation（−70°）, PR interval of 0.16s, QRS width of 0.16s, and complete right bundle branch block pattern（CRBBBp）（A）, followed by left axis deviation of−60°, PR interval 0.15s, QRS width 0.15s, and complete left bundle branch block pattern（CLBBBp）（B）a few tenths of a second later. Furthermore, an ECG at age 26 years of age showed a QRS waveform（C）with a QRS axis of ±0° shifting more rightward than A and B, PR interval 0.22s, QRS width 0.15s, and V₁ lead with rSr’ type mimicking CRBBBp. However, type C was considered a rather nonspecific intraventricular conduction delay based on S wave absence in the V₅ and V₆ leads. It is not appropriate to attribute the difference in conduction delay between the two bundle branches as the mechanism of the three ECG changes（A, B, and C）in this case. Triple pathway longitudinal dissociation in the His bundle could be indicated as the mechanism of these ECG changes based on the analysis of longitudinal dissociation. We report a previously unreported finding in a case of KSS with diverse conduction disturbances.

Complications of pacemaker implantation such as pneumothorax during venipuncture and cardiovascular injury during lead insertion, have been reported. With an incidence of about 1％, cardiac perforation is considered rare. However, it is a serious complication that may lead to cardiac tamponade and death. We report a case of a 70-year-old woman with a pneumothorax identified during post-operative follow-up. Eleven days after pacemaker implantation using an active fixation lead, a chest CT scan revealed a right pulmonary bulla and right pneumothorax. In addition, an elevated atrial pacing threshold and pericardial effusion were observed, and a pneumothorax due to lead perforation was suspected. In the surgical management of the right pneumothorax, thoracoscopy revealed that the tip of the active fixation lead had penetrated the right atrial wall and perforated the pericardium and pleura at a diameter of about 3mm on the ipsilateral side. The adjacent middle lobe of the right lung had been injured. Therefore, the pulmonary bulla was resected, the injured lung was repaired, and the lead was removed. When changes in threshold for endocardial wave height and abnormalities in the adjacent organs of the lead implantation site are observed, lead perforation should be suspected. If there is a perforation, removal should be actively considered.