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Biomedical subjects

Haruhiko Abe

Publications and source records attributed to Haruhiko Abe.

At least 19 recordsLinked to original sources
PubMed2006

Mental effect of cholesterol in males: protective effect?

BACKGROUND: While the benefits of low cholesterol for physical health are not in doubt, a potential negative aspect of low cholesterol for mental health is suggested by several studies. To examine the association between cholesterol and mental health, the authors performed an observational study. METHOD: From April 1995 to March 2002, a series of questionnaires pertaining to physical activity, food consumption, alcohol, coffee, smoking, and mental health (12 item-version of General Health Questionnaire: GHQ-12) were administered to 1972 employees in Japan. Subjects with less than 150 mg/dL of total cholesterol (very low cholesterol cohort) and other subjects (control cohort) were followed up for one to six years, and their mental health compared using GHQ caseness (GHQ-12 scores more than 3). RESULTS: Kaplan-Meier survival curves revealed that the very low cholesterol cohort had significantly greater GHQ caseness than the control cohort. Notably, this finding applied to males but not to females. After adjustment for general health, Cox's proportional hazards regression model confirmed this association in males only. The survival curves of control cohort were significantly different between males and females whereas those of very low cholesterol cohort were not. LIMITATIONS: GHQ caseness was regarded as "death" in the survival analysis. As such, it is not possible to differentiate between transient and persistent mental dysfunction and therefore may lead to overestimation of GHQ caseness over observational years. CONCLUSION: The present findings suggest that very low cholesterol may be associated with worse mental health in males and conversely and interestingly indicate that moderate (but not very low) cholesterol levels may protect mental health in males.

Adult↗
PubMed2006

Acute improvement in myocardial function assessed by myocardial strain and strain rate after aortic valve replacement for aortic stenosis.

OBJECTIVES: We investigated whether Doppler tissue imaging (tissue velocity, strain, and strain rate) could be useful to detect subtle left ventricular (LV) dysfunction in patients with aortic stenosis and changes in regional myocardial function after aortic valve replacement (AVR). METHODS: We studied 34 patients (age 69.2 +/- 10.4 years) with severe aortic stenosis, 21 of whom underwent AVR. Tissue velocity, systolic strain, strain rate, time to peak strain, and time to peak systolic and diastolic strain rates of basal and midsegments were measured in the apical 4-, 3-, and 2-chamber views before and 2 weeks after AVR. RESULTS: Strain and systolic strain rate showed the best correlation with LV ejection fraction (r = 0.80 and r = 0.70, respectively, both P < .0001). Early and late diastolic strain rates showed significant correlations with LV mass index (r = 0.45, P < .01; and r = 0.64, P < .0001, respectively) and time to peak strain, to peak systolic strain rate, and to peak early diastolic strain rate with aortic pressure gradient (r = 0.45, P < .01; r = 0.44, P < .01; and r = 0.56, P < .001, respectively) before AVR. Although LV mass index and LV systolic function did not change significantly after 2 weeks (LV mass index, 137 +/- 54 vs 125 +/- 36 g/m2; LV ejection fraction, 60 vs 58%, both P = not significant), peak strain and strain rates increased (P < .001) and time to peak strain and strain rate shortened after AVR (P < .001). Tissue velocities did not change significantly after AVR. CONCLUSIONS: Strain and strain rate parameters seemed to relate to LV function and aortic stenosis severity. Further, they seemed to be superior to tissue velocity and conventional echocardiography in detecting subtle changes in myocardial function after AVR before LV mass and LV function showed improvement.

Aged↗
PubMed2006

Comparison of HERG channel blocking effects of various beta-blockers-- implication for clinical strategy.

beta-Blockers are widely used in the treatment of cardiovascular diseases. However, their effects on HERG channels at comparable conditions remain to be defined. We investigated the direct acute effects of beta-blockers on HERG current and the molecular basis of drug binding to HERG channels with mutations of putative common binding site (Y652A and F656C). beta-Blockers were selected based on the receptor subtype. Wild-type, Y652A and F656C mutants of HERG channel were stably expressed in HEK293 cells, and the current was recorded by using whole-cell patch-clamp technique (23 degrees C). Carvedilol (nonselective), propranolol (nonselective) and ICI 118551 (beta(2)-selective) inhibited HERG current in a concentration-dependent manner (IC(50) 0.51, 3.9 and 9.2 microM, respectively). The IC(50) value for carvedilol was a clinically relevant concentration. High metoprolol (beta(1)-selective) concentrations were required for blockade (IC(50) 145 microM), and atenolol (beta(1)-selective) did not inhibit the HERG current. Inhibition of HERG current by carvedilol, propranolol and ICI 118551 was partially but significantly attenuated in Y652A and F656C mutant channels. Affinities of metoprolol to Y652A and F656C mutant channels were not different compared with the wild-type. HERG current block by all beta-blockers was not frequency-dependent. Drug affinities to HERG channels were different in beta-blockers. Our results provide additional strategies for clinical usage of beta-blockers. Atenolol and metoprolol may be preferable for patients with type 1 and 2 long QT syndrome. Carvedilol has a class III antiarrhythmic effect, which may provide the rationale for a favourable clinical outcome compared with other beta-blockers as suggested in the recent COMET (Carvedilol Or Metoprolol European Trial) substudy.

Adrenergic beta-Antagonists↗
PubMed2006

Comparison of the effects of VVI versus DDD pacing on cardiac baroreflex function.

INTRODUCTION: Conventional baroreceptor-heart rate (HR) reflex sensitivity cannot be examined in chronotropically incompetent patients or in pacemaker recipients. However, cardiac baroreceptor reflex sensitivity (BRS)-stroke volume (SV), which is closely and linearly correlated with BRS-HR, may be an alternative in that population. The aim of this study was to compare the BRS-SV in pacemaker recipients with a fixed HR paced in VVI versus DDD modes in the supine and upright positions. METHODS: The pacing mode was set randomly to DDD or VVI with complete atrial and/or ventricular capture, then crossed over to the alternate mode in 9 recipients of dual-chamber pacemakers with atrioventricular (AV) block. Beat-to-beat mean blood pressure and SV were measured in the supine and upright positions, using a tilt table. The BRS-SV, expressed in %/mmHg, was the ratio of low-frequency (LF) power to total power (TP) of SV variability, measured by spectral analysis of spontaneous variations in mean blood pressure and SV. RESULTS: BRS-SV was significantly lower in the VVI than in the DDD mode in the supine (37.2 +/- 26.7 vs 14.5 +/- 7.7%/mmHg) and upright (22.9 +/- 16.9 vs 10.6 +/- 6.6%/mmHg) positions (P < 0.05 for both comparisons). CONCLUSIONS: VVI pacing is adverse from the standpoint of cardiac autonomic baroreflex function. A decreased BRS-SV may be one of the factors involved in the hemodynamic intolerance associated with VVI pacing.

Aged↗
PubMed2005

Intrinsic mechanism of the enhanced rate-dependent QT shortening in the R1623Q mutant of the LQT3 syndrome.

OBJECTIVE: In the type 3 long QT syndrome (LQT3), arrhythmia events tend to occur at rest or during sleep. One of the mutations, R1623Q, is located in the voltage sensor of the cardiac sodium channel (hH1), and patients with R1623Q mutation have been also reported to show bradycardia-dependent cardiac events. Although the mutant channel has been characterized by inactivation gating defects, the intrinsic mechanism(s) that might explain why arrhythmia attack is most prevalent at slower heart rates has not been investigated. METHODS: cDNA encoding either the wild-type or the R1623Q mutant of hH1 was stably transfected into HEK293 cells. I(Na) was recorded using a whole-cell patch-clamp technique at 23 degrees C. RESULTS: A train of 50 depolarizing pulses from holding potentials (-120 and -80 mV) to -20 mV or a train of 50 action potential waveforms was applied at different frequencies. When using a rectangular waveform voltage clamp protocol, rate-dependent reduction of I(Na) was holding voltage-dependent but was not different between peak I(Na) and late I(Na). However, using the action potential clamp, preferential rate-dependent reduction of the phase 3 I(Na) was obvious as compared with peak I(Na). The discrepancy in the rate-dependent reduction between protocols was attributed to accelerated recovery from inactivation under non-equilibrium condition. CONCLUSION: The rate dependency of phase 3 I(Na) under non-equilibrium gating is a novel mechanism to explain the enhanced rate-dependent QT-shortening in LQT3 patients. Our findings are important for genotype-phenotype correlations in LQT3 mutants as well as for understanding the function of S4 segment of domain IV region in the cardiac Na(+) channel.

Action Potentials↗
PubMed2005

Blockade of HERG cardiac K+ current by antifungal drug miconazole.

1. Miconazole, an imidazole antifungal agent, is associated with acquired long QT syndrome and ventricular arrhythmias. Miconazole increases the plasma concentration of QT-prolonging drugs by inhibiting the hepatic cytochrome P450 metabolic pathway, but whether it has direct effects on cardiac ion channels has not been elucidated. 2. To determine the mechanism underlying these clinical findings, we investigated the effect of miconazole on human ether-a-go-go-related gene (HERG) K+ channels. 3. HERG channels were heterologously expressed in human embryonic kidney 293 (HEK293) cells and whole-cell currents were recorded using a patch-clamp technique (23 degrees C). 4. Miconazole inhibited HERG peak tail current in a concentration-dependent manner (0.4-40 microM) with an IC50 of 2.1 microM (n=3-5 cells at each concentration, Hill coefficient 1.2). HERG block was not frequency-dependent. It required channel activation, occurred rapidly, and had very slow dissociation properties. 5. The activation curve was shifted in a negative direction (V(1/2): -9.5+/-2.3 mV in controls and -15.3+/-2.4 mV after 4 microM miconazole, P<0.05, n=6). Miconazole did not change other channel kinetics (activation, deactivation, onset of inactivation, recovery from inactivation, steady-state inactivation). 6. The S6 domain mutation, F656C, abolished the inhibitory action of miconazole on HERG current indicating that miconazole preferentially binds to an aromatic amino-acid residue within the pore-S6 region. 7. Our findings indicate that miconazole causes HERG channel block by binding to a common drug receptor, and this involves preferential binding to activated channels. Thus, miconazole prolongs the QT interval by direct inhibition of HERG channels.

Action Potentials↗
PubMed2005

Home orthostatic self-training in neurocardiogenic syncope.

We assessed the efficacy of daily sessions of home orthostatic self-training (30 minutes per session standing against the wall without moving) in the prevention of neurocardiogenic syncope in 37 patients. Of these, 10 patients were instructed to perform two sessions per day, 14 were instructed to perform a single session per day, and the remaining 13 were instructed to perform one session every other day. The patients who performed one to two sessions of training per day continued to do so over a 6-month follow-up period, during that time none of them experienced spontaneous syncope. Only 5 of 13 patients who were instructed to train once every two days were able to continue doing so over the 6-month follow-up period; however, no spontaneous syncope was observed in these five patients. The remaining 8 of 13 patients could not continue their home training, and syncope or presyncope recurred in three of them during follow-up. We conclude that one session per day of home orthostatic self-training should be prescribed for the prevention of neurocardiogenic syncope.

Adult↗
PubMed2005

Prevalence of venous anatomic variants and occlusion among patients undergoing implantation of transvenous leads.

BACKGROUND: The implantation of transvenous leads may be prohibited by venous occlusion or anatomical variants. The prevalence of these conditions among patients undergoing transvenous pacing or implantable cardioverter defibrillator (ICD) leads implantation has not been systematically studied. This study examined the prevalence of venous anatomic variants and/or venous occlusion, and related risk factors, prior to lead implantation. METHOD: The study included 273 consecutive patients scheduled for implantation of transvenous pacing or ICD leads. Before the procedure, the venous network of arms, neck, and thorax was evaluated by bilateral intravenous digital subtraction angiography (DSA). RESULTS: Complete venous occlusion associated with developed collateral circulation was observed in 12 patients (4.4%); at the site of the left innominate vein in 9, left subclavian vein in 2, and right subclavian vein in 1 patient. Of 12 patients with venous occlusion, 7 patients had a history of prior surgical procedure. A persistent left superior vena cava was observed in 1 patient (0.4%). The presence of abnormal findings on DSA was significantly higher on the left than the right side (P < 0.001). The cardio-thoracic ratio (CTR) was significantly greater in patients with venous occlusions than patients with normal circulation (P = 0.012). CONCLUSIONS: Asymptomatic venous abnormalities are not rare among patients requiring transvenous pacing lead implantation. Careful attention should be paid when implanting pacing or ICD leads from the left side, especially in patients with an increased CTR or history of prior insertion for central venous catheter.

Aged↗
PubMed2005

Assessment of cardiac baroreflex function during fixed atrioventricular pacing using baroreceptor-stroke volume reflex sensitivity.

UNLABELLED: Baroreflex sensitivity in paced patients. INTRODUCTION: The baroreceptor-heart rate (HR) reflex has prognostic value in cardiovascular medicine. However, it cannot be used in chronotropically incompetent or paced patients. In healthy subjects, the baroreceptor-stroke volume (SV) reflex, with power spectral analysis of SV and blood pressure (BP) variations in the low-frequency band, serves as an alternate measure of the baroreceptor-cardiac reflex. This study examined the baroreceptor-stroke volume (SV) reflex sensitivity in the supine and 60 degrees upright positions in paced patients. METHODS AND RESULTS: We studied 16 recipients of dual-chamber pacemakers paced at a fixed rate. The hemodynamics and baroreceptor-SV reflex sensitivity were measured during atrioventricular (AV) sequential pacing every 5 minute in the supine and 60 degrees upright positions. Mean SV decreased from 42.0+/-20.1 mL in the supine to 36.6+/-16.1 mL in the upright position (P<0.05), whereas BP and total peripheral resistance did not change. A significant fall in baroreceptor-SV reflex sensitivity from 29.2+/-18.0%/mmHg to 19.5+/-15.5%/mmHg was observed during upright tilt (P<0.005). CONCLUSION: Fixed-rate AV sequential pacing did not blunt the decrease in baroreceptor-SV reflex sensitivity consistent with the arterial baroreflex gain response to upright posture. The decreased baroreceptor-SV reflex sensitivity occurring with the upright posture may reflect a baroreflex-induced inotropic effect secondary to vagal withdrawal and sympathetic activation.

Aged↗
PubMed2005

Successful treatment of cervical spinal epidural abscess by combined hyperbaric oxygenation.

A 49-year-old man underwent hyperbaric oxygen (HBO) therapy for the treatment of primary spinal epidural abscess. Although the epidural abscess was initially treated with antibiotic (cefozopran) for 5 days, he subsequently developed motor weakness, paresthesia and urinary retention. MRI demonstrated spinal cord compression at the C1-C4 level. HBO therapy was added to the antibiotic regimen, and three days later we found clinical evidence of a response to treatment. Neurological symptoms were relieved 13 days after HBO therapy. This case suggests that HBO therapy is an effective therapeutic adjunct for the treatment of spinal epidural abscess.

Anti-Bacterial Agents↗
PubMed2004

Cardiac autonomic balance and QT dispersion during head-up tilt testing in diabetics with and without sensory neuropathy.

BACKGROUND: Cardiovascular autonomic dysfunction is associated with higher mortality in diabetics. However, detection methods of early cardiac diabetic dysautonomia, and its correlation with severity of sensory neuropathy, have not been described. METHODS: We analyzed the heart rate variability (HRV) by spectral analysis and QT dispersion in 23 diabetics with and without sensory neuropathy, and in 5 age-matched controls, in the supine position and during head-up tilt testing (HUT). Diabetics were divided into 3 groups according to the degree of sensory neuropathy. RESULTS: In the spectral analysis of HRV, the high frequency components in the supine position decreased as a function of severity of the neuropathy. High frequency in diabetics was significantly decreased in the supine position, even in absence of sensory neuropathy. The low/high frequency ratio (L/H) in the supine position was similar among controls and the 3 patient groups. L/H in diabetics with moderate or severe neuropathy did not increase from the supine to the upright position. Baseline QT dispersion increased proportionally to the severity of sensory neuropathy and, in patients without apparent sensory neuropathy, QT dispersion increased significantly during HUT. CONCLUSIONS: The spectral analysis of HRV and measurements of QT dispersion, before and during HUT, were reliable detection methods of early abnormalities in autonomic balance and may predict a risk of sudden cardiac death in diabetics.

Aged↗
PubMed2004

Determination of baroreceptor-stroke volume reflex sensitivity by power spectral analysis: a quantitative probe of baroreceptor-cardiac reflex.

Baroreceptor-cardiac reflex, which consists of baroreceptor-induced chronotropic and inotropic actions, is a very useful index of cardiac sympathovagal balance. Baroreceptor-heart rate reflex sensitivity, which reflects baroreceptor-induced chronotropic action, has been used as a marker of baroreceptor-cardiac reflex. However, it cannot be used in patients with chronotropic incompetence and/or implanted cardiac pacemaker. We hypothesized that baroreceptor-stroke volume (SV) reflex sensitivity, which reflects baroreceptor-induced inotropic action, may also be a useful method for measurement of baroreceptor-cardiac reflex, similar to the baroreceptor-heart rate reflex sensitivity. To test this hypothesis, we measured baroreceptor-SV reflex sensitivity expressed as ratio of low frequency (LF) power to total power of SV fluctuation (LF/TP(SV): %/mmHg) by spectral analysis of mean blood pressure and SV fluctuations, the gain in low-frequency band between two signals in supine and 60 degrees upright positions, and compared these values to baroreceptor-heart rate reflex sensitivity in 14 healthy subjects. Baroreceptor-SV reflex sensitivity correlated significantly with baroreceptor-heart rate reflex sensitivity (r = 0.73, p < 0.0001). In addition, baroreceptor-SV reflex sensitivity correlated significantly and positively with high frequency (HF) power (r = 0.57, p < 0.005) and negatively with LF/HF ratio (r = -0.57, p < 0.005) in power spectral analysis of R-R interval variability. Moreover, baroreceptor-SV reflex sensitivity in LF/TP(SV) correlated positively with the R-R interval (r = 0.70, p < 0.0001) and negatively with diastolic blood pressure (r = -0.50, p < 0.01). We conclude that baroreceptor-SV reflex sensitivity in LF/TP(SV) can be used as a quantitative probe of baroreceptor-cardiac reflex, similar to the baroreceptor-heart rate reflex sensitivity in healthy subjects, and it may enable us to estimate inotropic aspect in baroreceptor-cardiac reflex in patients with chronotropic incompetence and/or implanted pacemaker.

Adult↗
PubMed2004

Twice-daily administration of a long-acting angiotensin-converting enzyme inhibitor has greater effects on neurohumoral factors than a once-daily regimen in patients with chronic congestive heart failure.

Although many clinical trials have evaluated the use of long-acting angiotensin-converting enzyme (ACE) inhibitors in patients with chronic congestive heart failure (CHF), there are no data regarding whether a once-daily or twice-daily regimen is preferable with respect to effects on the neuroendocrine system. To address this issue, the authors evaluated the comparative effects of the administration schedule on neurohumoral factors and autonomic nervous activity in patients with CHF. Thirty-two patients with mild compensated CHF received lisinopril (5-20 mg/d) orally either once a day (n = 17) or twice a day (n = 15) for more than 3 months. After this initial therapy, patients receiving a once-daily regimen switched to a twice-daily regimen and vice-versa, and patients were followed for an additional 3 months. Neurohumoral factors and the coefficient of variance in the electrocardiographic R-R interval (CVRR) were measured. Hemodynamic parameters, renal function, plasma concentrations of brain natriuretic peptide and aldosterone, and CVRR did not differ between the two regimens. However, the plasma concentration of norepinephrine was significantly lower, and plasma renin activity tended to be lower with the twice-daily regimen. These findings suggest that twice-daily administration of long-acting ACE inhibitors may have better effects on the neuroendocrine system than a once-daily regimen in patients with mild CHF.

Aged↗
PubMed2004

New onset of pacemaker dependency after permanent pacemaker implantation.

Pacemaker dependency has dangerous consequences under conditions of electromagnetic interference, unrecognized lead dysfunction, and battery depletion, and has been associated with cardiovascular and overall mortality. The aim of this study was to examine the incidence of new onset of pacemaker dependency during long-term follow-up after pacing system implantation. The study included 518 patients (mean age 72.9 +/- 10.4 years) who presented with intrinsic rhythms at the time of implantation. Indications for pacing were sick sinus syndrome (SSS) in 275 (53%) patients, AV block in 209 (40%), and AF with bradycardia in 34 (7%) patients. The mean follow-up was 3.7 +/- 2.7 years (range 1-17). Pacemaker dependency was defined as the absence of an intrinsic rhythm during backup pacing at 30 beats/min for 30 seconds. New onset of pacemaker dependency was observed in 23 (4.4%) of the 518 patients at a mean of 3.1 +/- 2.7 years of follow-up. Pacing indications were SSS in 6 (2.2%) of 275 patients, AV block in 15 (7.2%) of 209, and AF with bradycardia in 2 (5.9%) of 34. Patients with AV block had a significantly higher incidence of pacemaker dependency than patients with SSS (odds ratio 3.51; 95% CI 1.3 to 9.3; P = 0.012). The average annual rate of new pacemaker dependency was 1.6% during an 8-year follow-up. The incidence of new onset of pacemaker dependency varied among pacing indications, and was significantly higher in patients with AV block than patients with SSS.

Adolescent↗
PubMed2004

Alleviation of central sleep apnea by ventricular pacing in a patient with an implanted cardioverter defibrillator.

A 75-year-old man with a single chamber cardioverter defibrillator implanted for the management of sustained ventricular tachycardia developing after a healed myocardial infarction was admitted for evaluation of a sleep disorder. Polysomnography confirmed the presence of severe predominant central sleep apnea syndrome. The apnea-hypopnea index score decreased from 43.3 during spontaneous cardiac rhythm to 24.6 during VVI pacing at a rate of 70 beats/min. Ventricular pacing reduced the number of episodes of central sleep apnea/hypopnea without reducing the total sleep time, though it had no effect on episodes of obstructive sleep apnea/hypopnea.

Aged↗
PubMed2004

Anomalous right coronary artery originating from the distal left circumflex artery: single coronary artery with choronic atrial fibrillation.

This report describes a patient with a single coronary artery in whom the right coronary artery originated from the distal left circumflex artery. Single coronary artery is a rare congenital anomaly of the coronary circulation which is often associated with other congenital cardiac malformations. This anomaly is thought to be clinically significant especially in patients with atrial fibrillation, although no other associated cardiac anomaly was detected.

Angina Pectoris↗