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Yokohama-shi, Japan

Morishima I.,Ogaki Municipal Hospital | Nogami A.,Yokohama Rosai Hospital | Tsuboi H.,Ogaki Municipal Hospital | Sone T.,Ogaki Municipal Hospital
Journal of Cardiovascular Electrophysiology | Year: 2012

Left Posterior Fascicle and Idiopathic Left VT. The left posterior fascicle may be a bystander of the circuit of verapamil-sensitive idiopathic left ventricular tachycardia. During ventricular tachycardia (VT), 3 sequences of potentials were seen at the left posterior septum: diastolic Purkinje potentials propagating from base to apex and presystolic left posterior fascicular potentials and systolic left ventricular (LV) myocardial potentials propagating in the reverse direction. Selective capture of the left posterior fascicle by the sinus beat did not affect the VT cycle length. Entrainment pacing revealed that the retrograde limb of the circuit was not the left posterior fascicle, but the LV myocardium. © 2012 Wiley Periodicals, Inc.

Akihiko N.,Yokohama Rosai Hospital
PACE - Pacing and Clinical Electrophysiology | Year: 2011

Purkinje-related monomorphic ventricular tachycardias (VTs) can be classified into four distinct groups: (1) verapamil-sensitive left fascicular VT, (2) Purkinje fiber-mediated VT post infarction, (3) bundle branch reentry (BBR) and interfascicular reentry VTs, and (4) focal Purkinje VT. There are three subtypes of fascicular VTs: (1) left posterior fascicular VT with a right bundle branch block (RBBB) configuration and superior axis; (2) left anterior fascicular VT with an RBBB configuration and right-axis deviation; and (3) upper septal fascicular VT with a narrow QRS configuration. The mechanism of the fascicular VT is macroreentry. While the antegrade limb of the circuit is amidseptal abnormal Purkinje fiber in the anterior and posterior fascicular VTs, the antegrade limb of the upper septal fascicular VT is both the anterior and posterior fascicles, and the retrograde limb is a midseptal abnormal Purkinje fiber. Purkinje fibermediated VT post infarction also exhibits verapamil sensitivity, and the surviving muscle bundles within the myocardium and Purkinje system are components of the reentry circuit. BBR-VT and interfascicular reentry VT are amenable to being cured by the creation of bundle or fascicular block. The mechanism of focal Purkinje VT is abnormal automaticity from the distal Purkinje system, and the ablation target is the earliest Purkinje activation during the VT. It is difficult to distinguish verapamil-sensitive fascicular VT from focal Purkinje VT by the 12-lead electrocardiogram; however, focal Purkinje VT is not responsive to verapamil. The recognition of the heterogeneity of these VTs and their unique characteristics should facilitate an appropriate diagnosis and therapy. ©2011, The Author. Journal compilation ©2011 Wiley Periodicals, Inc.

The authors retrospectively studied the mechanism of cyst formation and enlargement after Gamma Knife surgery (GKS) for arteriovenous malformations (AVMs). Eighteen patients in whom cyst formation developed following GKS for AVM were retrospectively identified among 775 patients who underwent GKS for AVM at Yokohama Rosai Hospital. The study group was composed of 12 male and 6 female patients ranging in age from 17 to 47 years. Chronic encapsulated expanding hematoma was associated with the cyst in 5 patients. The AVM nidus volume at the time of GKS ranged from 1.9 to 36 cm(3), and the prescription radiation dose was 18-25 Gy. Complete obliteration of the AVM nidus was obtained in 13 patients and partial obliteration in 5 patients. Cyst formation was detected between 2.6 and 15 years after GKS. Craniotomy was performed in 10 patients, including 2 patients in whom the incompletely obliterated nidus was removed at the same time, and an Ommaya reservoir was placed in 2 patients. Spontaneous regression of the cyst was observed in 1 patient. Serial MR imaging was performed in the other patients because the size of the cyst was stable or the lesion was asymptomatic. Histological examination of the cyst wall revealed linear hemosiderin deposits with gliosis. The nodular lesion, which was enhanced on MR images, contained granulation tissue with chronic hemorrhage from newly developed capillary vessels. Cysts developing after GKS for AVM enlarge mainly due to repeated minor hemorrhages from a reddish nodular angiomatous lesion that develops within an adjacent brain area. Thus, the optimal treatment is wide opening of the cyst with removal of the associated angiomatous lesion by craniotomy.

Nogami A.,Yokohama Rosai Hospital
PACE - Pacing and Clinical Electrophysiology | Year: 2011

There has been growing evidence that the Purkinje network plays a pivotal role in both the initiation and perpetuation of ventricular fibrillation (VF). A triggering ventricular premature beat (VPB) with a short-coupling interval could arise from either the right or left Purkinje system in patients with polymorphic ventricular tachycardia (VT) or VF, and that can be suppressed by the catheter ablation of the trigger. A focal breakdown in the "gating mechanism" at the Purkinje system resulting in a short-circuiting of the transmission across the gate at the distal Purkinje network might predispose to reentrant circuits of polymorphic VT/VF. Many investigators also reported the successful ablation of Purkinje-related VF with an acute or remote myocardial infarction. The same approach with good short-term results has been reported in a small number of patients with other heart diseases (i.e., amyloidosis, chronic myocarditis, nonischemic cardiomyopathy). Catheter ablation of the triggering VPBs from the Purkinje system can be used as an electrical bailout therapy in patients with VF storm. © 2010 Wiley Periodicals, Inc.

The prognosis of metastatic or recurrent gastrointestinal stromal tumors (GISTs) accompanied by multiple hepatic metastases and peritoneal dissemination is very poor. We encountered a case of stage IV small intestinal GIST with multiple hepatic metastases and peritoneal dissemination that were observed after resection of the primary lesion. Multidisciplinary treatments were performed over time, including hepatic resection, radiotherapy, imatinib therapy, sunitinib therapy, and transcatheter arterial chemoembolization, and the disease had been brought under control following resection of a primary lesion 14 years ago. The patient was a 49-year-old woman diagnosed with hemorrhagic stool in July 1998, when a computed tomography scan revealed an 8-cm-diameter tumor in her small bowel. Partial resection of her small bowel was performed and the pathological diagnosis was a high-risk GIST showing 15 mitoses per 50 high power fields. Several metastases developed in the S4 and S5 segments of the patient's liver 3 years after resection of the primary lesion, and a central two-segmental resection of the liver was performed. Furthermore, 1 year after this procedure, peritoneal dissemination developed near the pancreas, for which radiotherapy was performed. Four months later, the patient again developed multiple liver metastases and was started on treatment with 400 mg imatinib per day, achieving a partial response(PR). Five years and 6 months after imatinib initiation, resistance emerged in one of the liver metastases. The patient was switched to sunitinib(50 mg per day), but was diagnosed with progressive disease at the end of the second course and the procedure was discontinued. Treatment with 400 mg of imatinib per day was resumed, and transcatheter arterial chemoembolization was performed twice over a 17-month period for the resistant hepatic region and a PR was achieved each time. We were able to maintain a PR in this patient; other metastases indicated the effectiveness of imatinib therapy. Therefore, a multidisciplinary team approach can be effective in achieving long-term disease control in patients with metastatic or recurrent GIST.

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