[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

We investigated the incidence of heart failure in patients after pacemaker implantation. Three ventricular pacing mode groups, designated VDD, DDD and VVI, were observed (AAI mode was not) . The number of patients observed was 209. As for the rate of heart failure (HF) hospitalization, the VDD group had 1 in 21 patients (4.8%) , the DDD group had 3 in 105 (2.9%) , and the VVI group had 14 in 83 (16.9%) . The HF hospitalization rate in the VVI group was higher than the other groups. The average age was 77.7±9.5 years old, with 104 males and 105 females, and 59.0±30.4 months for the average observation period. The average left ventricular ejection fraction (LVEF) by echocardiogram was 68.7± 9.4%. Patient background and the risk of atrial fibrillation increased did not differ by pacing mode, and there was no significant difference in paced QRS duration. Therefore, the importance of atrio-ventricular synchronization was strongly suggested. Based on these results, there is a high probability that physiologic pacing prevents heart failure.

View full abstract

In the currently available cardiac differentiation system in pluripotent stem cells, the number of differentiating pacemaker cells is not sufficient to use cell therapy of bradycardia because of their limited efficacy in cardiac differentiation. Therefore, it is important to establish the method of an effective cardiac differentiation system. For this purpose, we studied the role of Heterochromatin protein 1γ (HP1γ) in cardiac differentiation. We first established several HP1γover-expressing P19 embryonal carcinoma cell lines (HP1γ-P19) . Although wild type-P19 cells did not differentiate into cardiac cells, HP1γ-P19 cells differentiated into cardiac cells with spontaneous beating after embryoid body (EB) formation, indicating that HP1γfacilitated cardiac differentiation. RT-PCR analysis revealed that HP1γ-P19 EBs expressed various cardiac differentiation marker genes. Immunostaining showed that the beating cardiomyocytes derived from HP1γ-P19 cells expressed cardiac contractile proteins, cardiac ion channel proteins and cardiac specific gap junction proteins. Flow cytometer analysis showed that EBs derived from HP1γ-P19 cells involved the higher prevalence of cardiac stem cells expressing Flk-1 and prion protein. Electrophysiological study indicated that the differentiated cells from HP1γ-P19 cells revealed spontaneous action potential associated with cardiac-specific K⁺ channel currents, Ca²⁺ channel currents and Na⁺ channel currents. Cardiomyocytes derived from HP1γ-P19 cells were able to respond to autonomous nerve system agonists such as isoproterenol and carbachol. These data suggest that HP1γfacilitated differentiation of P19 cells into cardiac stem cells and promoted their maturation into cardiac cells involving pacemaker cells.

View full abstract

We present the case of a 71-year-old male patient who was admitted to our hospital for fever and implantable cardioverter defibrillator (ICD) shocks for ventricular fibrillation (VF) . He has a strong family history of sudden death. He had a history of syncope at age 54. He suffered cardiopulmonary arrest at age 64, and survived by the cardio-pulmonary resuscitation. ECG showed complete right bundle branch block (QRS duration : 170msec, notch in precordial leads V₁-V₂) . Single-averaged ECG revealed a positive result. Investigations such as echocardiography, myocardial scintigraphy, cardiac magnetic resonance imaging, coronary angiography, myocardial biopsy did not reveal any significant cardiac abnormalities. Coved type ST-T elevation was observed by the pilsicainide challenge test. We considered the possibility of the Brugada syndrome or the early stage of the arrhythmogenic right ventricular cardiomyopathy, and implanted an ICD at that time. His condition has been stable for six years after the ICD implantation. During this hospitalization, however, it was difficult to control VF, because the VF was triggered by a fever of unknown origin. This patient case may be helpful to learn the differential diagnosis of the primary disease of VF and how to deal with VF triggered by fever.

View full abstract