Biomedical subjects

Atsuyuki Watanabe

Publications and source records attributed to Atsuyuki Watanabe.

6 recordsLinked to original sources

PubMed2006

Low-dose isoproterenol for repetitive ventricular arrhythmia in patients with Brugada syndrome.

AIMS: Arrhythmic storm or repetitive ventricular arrhythmia (VA) has been occasionally observed in Brugada syndrome (BS). A beta-adrenergic stimulator [isoproterenol (ISP)] has been reported to suppress this arrhythmic storm in sporadic cases. Accordingly, we investigated the antiarrhythmic effects of ISP infusion in consecutive BS patients with arrhythmic storm or repetitive VA. METHODS AND RESULTS: Seven BS patients with arrhythmic storm were studied. Intravenous ISP was administered as a bolus injection (1-2 microg), followed by continuous infusion (0.15 microg/min). Arrhythmic storm or repetitive VA was suppressed immediately after the bolus administration of ISP, which was followed by continuous infusion of low-dose ISP for 1-3 days. In all patients, ST-elevation decreased in right precordial leads. In six of the seven patients, VA subsided after the discontinuance of ISP. RR interval was shortened and ST-elevation in right precordial leads was decreased after ISP bolus injection. ST-elevation in right precordial leads remained decreased during continuous ISP infusion, whereas the RR interval returned to the control level. CONCLUSION: Continuous administration of low-dose ISP may be effective for the suppression of repetitive VA occurrence in patients with BS.

Adrenergic beta-Agonists↗

PubMed2006

Elevated levels of oxidative DNA damage in serum and myocardium of patients with heart failure.

BACKGROUND: Oxidative stress has been implicated in the pathogenesis of chronic heart failure. The present study investigated whether the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were elevated in the serum and myocardium of patients with dilated cardiomyopathy (DCM), and furthermore whether carvedilol, a vasodilating beta-blocker with antioxidant activity, could reduce the levels. METHODS AND RESULTS: Serum levels of 8-OHdG were measured by enzyme immunoassay in 56 patients with DCM and in 20 control subjects. DCM patients had significantly elevated serum levels of 8-OHdG compared with control subjects. Endomyocardial biopsy samples obtained from 12 DCM patients and 5 control subjects with normal cardiac function were studied immunohistochemically for the expression of 8-OHdG. Positive 8-OHdG staining was found in the nuclei of cardiomyocytes from DCM patients but not in those from control subjects. After treatment with carvedilol, the serum levels of 8-OHdG in DCM patients significantly decreased by 19%, together with amelioration of heart failure. CONCLUSIONS: Levels of 8-OHdG are elevated in the serum and myocardium of patients with heart failure. Treatment with carvedilol might be effective for decreasing the oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2006

Continuous positive airway pressure ameliorated severe pulmonary hypertension associated with obstructive sleep apnea.

A 52-year-old obese woman was admitted to our institution for evaluation of dyspnea and pulmonary hypertension (PH). Polysomnography revealed severe obstructive sleep apnea (OSA) with an apnea hypopnea index of 99.8. Treatment with nocturnal continuous positive airway pressure (CPAP) resulted in correction of daytime hypoxemia, hypercapnia, and near-normalization of pulmonary artery pressure. To our knowledge, this is the most severe case of OSA-associated PH (approximately70 mmHg) reported to date, and it was successfully treated with nocturnal CPAP. This case demonstrates that OSA should be considered and polysomnography performed in all patients with PH, irrespective of severity, and that nocturnal CPAP has therapeutic effects on both OSA and daytime PH.

Continuous Positive Airway Pressure↗

PubMed2005

[Long QT syndrome].

The long QT syndrome (LQTS) is characterized by prolongation of the QT interval, causing torsade de pointes and sudden cardiac death. This syndrome can be divided into idiopathic (congenital) and acquired forms. The idiopathic form is a familial disorder that can be associated with sensorineural deafness (Jervell and Lange--Nielsen syndrome, autosomal recessive) or normal hearing (Romano--Ward syndrome, autosomal dominant). The acquired form has a long QT interval caused by various drugs such as quinidine sotalol and dofetilide, also by noncardiovascular drugs such as antihistamine, antibiotics, antipsychotics and others. Also, the QT interval is prolonged by electrolyte abnormalities such as hypokalemia and hypomagnesemia, central nervous system lesions, significant bradyarrhythmias, cardiac ganglionitis, mitral valve prolapse and probucol. DNA variants appearing to predispose to drug-associated acquired long QT syndrome have been reported in congenital long QT.

Death, Sudden, Cardiac↗

PubMed2004

Sinus node function in patients with Brugada-type ECG.

BACKGROUND: Some studies have shown that patients with Brugada syndrome (BS) have atrioventricular conduction disturbance, but their sinus node function has not been evaluated. METHODS AND RESULTS: The patients group consisted of 59 male patients and 1 female patient with BS. Supraventricular and ventricular programmed electrical stimulation (PES) was performed. Ventricular fibrillation (VF) or sustained polymorphic ventricular tachycardia was induced by ventricular PES in 26 patients with BS (VF group), but was not induced in the other 34 patients (non-VF group). Sinus node function and conduction of the atrioventricular (AV) node in the control group, non-VF group and VF group were evaluated. Sinus node function was attenuated and the His - ventricle interval was prolonged in the VF group (corrected sinus node recovery time: 452+/-126 ms (VF group), 324+/-146 ms (non-VF group), Sino-atrial conduction time: 179+/-60 ms (VF group), 127+/-60 ms (non-VF group), His-ventricle interval: 41+/-9 ms (VF group), 35+/-8 ms (non-VF group)). CONCLUSION: The function of both the sinus node and AV node are attenuated in patients with PES-induced VF.

Adult↗

PubMed2003

Ventricular arrhythmia induced by sodium channel blocker in patients with Brugada syndrome.

OBJECTIVES: We administered pilsicainide chloride, a class Ic pure sodium channel blocker, to patients with Brugada syndrome (BS) and evaluated the occurrence of ventricular arrhythmia (VA) and T-wave alternans (TWA). BACKGROUND: Ventricular arrhythmia and TWA are sometimes induced by a sodium channel blocker challenge test in BS patients, but the significance of the induced VA and TWA is not known. METHODS: Pilsicainide was administered to 65 patients with BS (10 symptomatic and 55 asymptomatic patients), and the occurrence of VA, TWA, and change of electrocardiogram were evaluated. Electrophysiologic study was performed in 57 patients, and the induction of VA by programmed electrical stimulation (PES) was evaluated. RESULTS: Ventricular arrhythmia was not induced by administration of pilsicainide in 55 patients (no-VA group). Administration of pilsicainide-induced VA in 10 patients (Pil-VA group) and polymorphic ventricular tachycardia in four patients. Pilsicainide-induced VA in 60% of the symptomatic patients but in only 7% of asymptomatic patients (p < 0.01). ST level, QTc, and indexes of cardiac conduction in the Pil-VA group were not different from those in the no-VA group. Ventricular fibrillation was induced by PES in 67% of the patients in the Pil-VA group and in 33% of the patients in the no-VA group. In six cases, macroscopic TWA occurred in association with pilsicainide-induced VA, but TWA occurred in only one patient without pilsicainide-induced arrhythmia. CONCLUSIONS: Administration of a sodium channel blocker results in induction of not only ST-elevation but also VA and TWA in patients with BS.

Adult↗