Publications by authors named "Masaaki Kurata"

Background: The utility of repeat ablation for premature ventricular contractions (PVCs) after prior ablation failure is not clear.

Objective: The purpose of this study was to assess the outcomes of repeat ablation and the use of different techniques in patients who failed prior PVC ablation.

Methods: We reviewed 239 consecutive patients who underwent PVC ablation.

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Background: Patients with ventricular tachycardia (VT) frequently present in unstable VT and are subject to urgent/high-risk ablation procedures. Clinical predictors of prolonged hospitalization and mortality are needed for optimal management of these patients.

Objectives: This study seeks to identify factors associated with prolonged hospitalization and mortality in emergent unplanned VT ablation procedures.

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Background: Irrigated radiofrequency ablation with half-normal saline can potentially increase lesion size but may increase the risk of steam pops with the risk of emboli or perforation. We hypothesized that pops would be preceded by intracardiac echocardiography (ICE) findings as well as a large impedance fall.

Methods: In 100 consecutive patients undergoing endocardial ventricular arrhythmia radiofrequency ablation with half-normal saline, we attempted to observe the ablation site with ICE.

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Introduction: When ventricular tachycardia (VT) recurs after standard RF ablation (sRFA) some patients benefit from repeat sRFA, whereas others warrant advanced methods such as intramural needle ablation (INA). Our objectives are to assess the utility of repeat sRFA and to clarify the benefit of INA when repeat sRFA fails in patients with VT due to structural heart disease.

Methods: In consecutive patients who were prospectively enrolled in a study for INA for recurrent sustained monomorphic VT despite sRFA, repeat sRFA was considered first.

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Aims: Failure of radiofrequency (RF) ablation of ventricular arrhythmias is often due to inadequate lesion size. Irrigated RF ablation with half-normal saline (HNS) has the potential to increase lesion size and reduce sodium delivery to the patient if the same volume of RF irrigant were used for normal saline (NS) and HNS but could increase risks related to steam pops and lesion size. This study aims to assess periprocedural complications and acute ablation outcome of ventricular arrhythmias ablation with HNS.

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Article Synopsis
  • * 663 procedures were assessed, revealing low rates of stroke (0.3%) and bleeding complications (5.9%), with associations found between pre-procedure antithrombotic medications and increased bleeding risk.
  • * The findings suggest that while strokes are rare, using aspirin (ASA) as a minimum post-procedure regimen is effective, indicating that stronger medications may be needed for certain patients based on their individual risk factors.
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Background: We previously reported feasibility of irrigated needle ablation (INA) with a retractable 27-G end-hole needle catheter to treat nonendocardial ventricular arrhythmia substrate, an important cause of ablation failure.

Objectives: The purpose of this study was to report outcomes and complications in our entire INA-treated population.

Methods: Patients with recurrent sustained monomorphic ventricular tachycardia (VT) or high-density premature ventricular contractions (PVCs) despite radiofrequency ablation were prospectively enrolled at 4 centers.

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Objective: The present report characterises a spontaneous nictitating membrane abnormality in a Japanese white rabbit.

Animal Studied: The animal was a male Japanese white rabbit (Oryctolagus cuniculus, Kbs:JW, 10 weeks old at the time of purchase) that had not received any treatment. A morphological abnormality of the nictitating membrane in the animal's right eye was detected.

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Background: In eye-drop drug development, the additional genotoxicity tests in some cases might be necessary to assess genotoxicity in the ocular surface since the ocular surface is exposed directly to high drug concentrations. Recently, an in vivo comet assay using corneal epithelial cells in rabbits following single ocular instillation was developed as an assay to evaluate genotoxicity in ocular tissues. In this study, we investigated the time-course changes in DNA damage after ocular instillation of genotoxic compounds to evaluate the optimal sampling timing for in vivo comet assay of the ocular surface tissue.

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Backgrounds: An adverse increased risk of atrial fibrillation (AF) can be detected by measuring the p-wave indices, including prolonged p-wave duration, the PR interval, abnormal p-wave terminal force, and abnormal p-wave axis (aPWA). Our purpose was to characterize the AF patient population with an aPWA and to identify whether the aPWA was associated with recurrence after catheter ablation of AF.

Methods: This study retrospectively included 249 patients with AF who underwent catheter ablation in our hospital from October 2015 to May 2019.

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Rabbits are sometimes used for intranasal toxicology studies. We investigated the postnatal development of the nasal passage in juvenile Japanese white rabbits from just after birth to 6-week-old to provide information for conducting intranasal toxicological evaluation using juvenile animals. On postnatal day (PND) 1, the nasal passage consisted of the septum with mostly cartilaginous nasal wall and turbinates.

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Nickel subsulfide (NiS) is known to induce intraocular neoplasms when injected intravitreally into the eyes of rats. Here, we found two extraocular orbital neoplasms in two different rat strains, presumably due to the leakage of locally injected NiS to the extraocular orbital tissues. In the F344/DuCrlCrlj rat, an orbital mass arose at 30 weeks after injection, and invaded into the cranium.

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Background: The in vivo comet assay is used to evaluate the genotoxic potential of compounds by detecting DNA strand breaks in cells isolated from animal tissue. The comet assay of hepatocytes is well established; however, the levels of systemic drug exposure following systemic administration are often insufficient to evaluate the genotoxic potential of compounds on the ocular surface following ocular instillation. To investigate the possibility of using the comet assay as a genotoxic evaluation tool for the ocular surface, we performed this assay on the corneal epithelial cells of rabbit eyes 2 h after the single ocular instillation of five genotoxic compounds, namely ethidium bromide, 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat), methyl methanesulfonate (MMS), acrylamide, and 4-nitroquinoline 1-oxide (4-NQO).

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Background: Insertable cardiac monitors (ICMs) improve diagnostic yield in patients with unexplained syncope. The most of cardiac syncope is arrhythmic causes include paroxysmal bradycardia and supraventricular tachycardia (SVT) in patients with unexplained syncope receiving ICM. Predictors for bradycardia and SVT that necessitate therapy in patients with unexplained syncope are not well known.

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Purpose: An unscheduled DNA synthesis (UDS) test is used for or genotoxicity evaluation. The UDS test with hepatocytes is well established; however, drug exposure levels at the application site for topically administered drugs (e.g.

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Article Synopsis
  • Ventricular septal perforation (VSP) has a high mortality rate post-surgery, and traditional surgical approaches usually involve left ventricular (LV) incisions, which carry risks.
  • This case discusses a right ventricular (RV) surgical approach for a 76-year-old male with VSP after a myocardial infarction caused by left anterior descending artery (LAD) occlusion, which led to a positive outcome.
  • The RV method minimizes the risk of damaging the left ventricle and preserves its function, utilizing a specialized “sandwich technique” for patching the perforation with a combination of materials for better stability.
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Article Synopsis
  • - The study aimed to compare how well brimonidine (BMD) and brinzolamide (BZM) are absorbed in the body when given together as a fixed-combination drug versus when they are administered separately to rabbits.
  • - Researchers measured the concentration of both drugs in different parts of the eye and in the blood using advanced testing methods after administering the drugs in various formulations.
  • - Results indicated that the fixed combination (FCBB) produced similar drug levels in the eye and bloodstream as the individual drugs, suggesting that the combined formulation may improve drug distribution, particularly in certain eye tissues, and that the timing of administration can affect absorption.
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Rabbits are frequently used in studies assessing the toxicity of ophthalmic drugs; however, the postnatal histological changes that occur in the rabbit eye have not been fully described. To characterize postnatal ocular development in white rabbits, a histological investigation of the eyes and eyelids was sequentially performed between postnatal days (PNDs) 1 and 42. The eyes opened during PNDs10 to 12.

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Pacemaker implantations are minimally invasive procedures commonly used for patients with bradycardic arrhythmias. Takotsubo cardiomyopathy, which is usually induced by life-threatening stress hardly ever occurs after this minimally invasive procedure. Here, we experienced a patient who developed takotsubo cardiomyopathy leading to ventricular fibrillation the day after a pacemaker implantation.

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Introduction: This study was aimed to compare ocular tissue distribution and systemic exposure of brimonidine and timolol after single topical administration to rabbits of fixed-combination ophthalmic solution of 0.1% brimonidine tartrate and 0.5% timolol and single drugs (0.

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Introduction: Azithromycin demonstrates high tissue distribution and prolonged elimination half-life. In this study, we monitored the pharmacokinetics of a single ophthalmic administration of 1% azithromycin ophthalmic solution containing polycarbophil in the extraocular tissues, including the eyelid, and compared it with that of two commercial ophthalmic products, 1.5% levofloxacin ophthalmic solution and 0.

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A comet assay is one of the genotoxicity methods for evaluating the potential of chemicals to induce DNA strand breaks. To investigate the usefulness of comet assays for evaluating the genotoxic potential of ophthalmic solutions, a three-dimensional (3D) reconstructed human corneal epithelial model (3D corneal model) was exposed to conditions mimicking topical ocular instillation administration. The 3D corneal model was exposed to acridine orange, ethidium bromide, hydrogen peroxide, 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat), 4-nitroquinoline 1-oxide (4-NQO), acrylamide and methyl methanesulfonate (MMS).

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Background: Left atrial (LA) dilation is associated with morbidity of atrial fibrillation (AF). However, little is known about pulmonary vein (PV) dilation.

Purpose: We investigated the PV volume in the patients with AF.

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