Brugada syndrome (BrS) is a distinct form of idiopathic ventricular fibrillation (VF). BrS is characterized by a unique electrocardiographic pattern consisting of a right bundle branch block morphology and ST-segment elevation in the right precordial leads. There are 2 leading hypotheses for the mechanisms underlying BrS phenotype and arrhythmias: (1) The abnormal repolarization hypothesis (based on the canine wedge preparation), i.e., spatially heterogeneous loss of the action potential plateau in the right ventricular outflow tract (RVOT) can lead to reentry (phase 2 reentry). (2) The abnormal conduction hypothesis (based on whole-heart studies in BrS patients). In this review, the author describes the possible mechanisms based on the results of studies performed by the author and colleagues. The abnormal conduction hypothesis is supported by positive ventricular late potentials based upon signal averages ECG, higher incidence of inducible VF by programmed ventricular stimulation, the presence of fragmented and delayed potentials in the RVOT, and the higher prevalence of abnormal findings of the right ventricular biopsy specimen. On the other hand, the abnormal repolarization hypothesis is supported by the presence of STT alternans in the ECG and monophasic action potential duration alternans in the RVOT. High-resolution 187-channel ECG revealed that ECG phenotype was related to the spatial and transmural dispersion of repolarization, but lethal arrhythmia was related to the presence of ventricular late potential. Therefore, we hypothesize that the ECG phenotype of BrS may be related to both abnormal repolarization and conduction, and that the development of VF may be related mainly to abnormal conduction.

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Background: Cryoballoon ablation for pulmonary vein isolation (PVI) is efficacious for the treatment of paroxysmal atrial fibrillation (PAF). However, the effectiveness of cryoballoon-based PVI on the left atrial (LA) ganglionated plexi (GPs) has not been reported. Therefore, we conducted a retrospective study in which we compared vagal responses during cryoballoon ablation (CBA) or radiofrequency ablation (RFA) for PVI. Methods: The study included 49 patients with AF (23 women and 26 men, 62.7 ± 10.9 years of age) who were symptomatic, despite treatment with 1 or more antiarrhythmic drugs, and thus underwent PVI by means of CBA or RCA. High-frequency stimulation (20 Hz, 25 mA, 10 ms) was performed at 5 major LA GP sites before and after PVI in 18 patients treated by RFA and in 31 patients treated by CBA, and vagal responses and treatment outcomes were compared between the 2 patient groups. Results: Elimination of the vagal responses was similar between the 2 groups. At a median follow-up of 7 (3-9) months, AF recurred in 1 of the 31 (3.2%) patients treated with CBA and in 2 of the 18 (11.1%) patients treated with RFA ( p = 0.3017). Conclusion: The efficacy of CBA for AF may be due in part to ablation of the LA GPs that occurs during PVI.

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Objectives: Dexmedetomidine, a highly selective α₂-adrenergic receptor agonist, is often used for sedation during the perioperative period. Dexmedetomidine has complex effects on the cardiovascular system. The loading dose of dexmedetomidine increases the arterial pressure and decreases the heart rate, implying changes in arterialcardiac baroreflex. Many previous studies have reported various effects of dexmedetomidine on the cardiac responses to changes in arterial pressure. However, the effect of the loading dose of dexmedetomidine on the arterial-cardiac baroreflex has not been studied. Therefore, we investigated the effect of the loading dose of dexmedetomidine on the arterial-cardiac baroreflex. Methods: Twelve healthy men received loading dose dexmedetomidine (6 μg/kg/h for 10 minutes). Before and during dexmedetomidine infusion, beat-to-beat of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and R-R intervals were recorded. Arterial-cardiac baroreflex function was assessed by sequence analysis between beat-to-beat changes in the SAP and R-R interval. Results: During the infusion of a loading dose of dexmedetomidine, SAP and DAP increased significantly, and heart rate decreased significantly. All indices of arterial-cardiac baroreflex function increased significantly (total-slope: 20.3 ± 14.6 → 29.4 ± 17.4 ms/mmHg; up-slope: 19.9 ± 13.0 → 28.0 ± 14.3 ms/mmHg; down-slope: 20.0 ± 15.8 → 30.3 ± 19.9 ms/mmHg). Conclusions: The present results indicate that the loading dose of dexmedetomidine augments the arterialcardiac baroreflex, which may contribute to stabilization of haemodynamics, even in situations in which arterial blood pressure changes rapidly in response to perioperative stimuli.

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Perforation of the colon after barium gastrography is extremely rare. We report two cases of the disease with a review of the literature. Case 1 involved a 68-year-old male who presented with abdominal pain the day after undergoing barium study for gastric cancer screening. Abdominal Computed Tomography (CT) and Gastrografin Enema (GE) suggested perforation of the sigmoid colon. An emergency operation revealed a 6-cm perforation in the sigmoid colon. Hartmann′s operation and drainage were performed. Case 2 involved a 48-year-old female who presented with abdominal pain two days after undergoing barium study for gastric cancer screening. Abdominal CT and GE suggested perforation of the descending colon. An emergency operation revealed a 5-cm perforation in the descending colon. Descending colon resection and colostomy were performed. Colonic perforation is one of the complications of barium gastrography, but it occurs rarely. It is important to consider the selection of modality for gastric cancer screening and the risk management of barium gastrography.

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We experienced a case of advanced bilateral breast cancer during pregnancy. A 38-year-old woman complained of a breast lump in her right breast. She had noticed the lump two months before. She was pregnant at 5-months gestation. Ultrasonography revealed a huge tumor in her right breast, and also revealed swelling of the right side axillary lymph nodes. Furthermore, ultrasonography showed a low echoic mass, 10 mm in diameter, on her left breast. We performed core needle biopsies of these tumors. Both breast tumors were diagnosed as invasive ductal carcinomas. After waiting for the patient to give birth, we administered 25 cycles of TC chemotherapy (Docetaxel: 75 mg/m2/tri-weekly, Cyclophosphamide: 600 mg/m2/tri-weekly). After chemotherapy, she underwent bilateral radical mastectomy. The pathological diagnoses from both sides of the breasts were complete responsiveness to chemotherapy. She continues to be well without recurrence.

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A 75-year-old man presented with bloody stool. Hemorrhagic gastric ulcer and infectious pancreatic pseudocyst was diagnosed at another hospital and the patient was transferred to our hospital for treatment. Abdominal computed tomography scan revealed infectious pancreatic pseudocyst with a pancreatic stone, pancreatic pleural effusion and subcutaneous fistula. We performed distal pancreatectomy and fistula closure with the omentum. The postoperative course was uneventful. Pancreatic pleural effusion and subcutaneous fistula are very rare. Herein, we report this case with a review of the literature.

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