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Teruhisa Tanabe

Publications and source records attributed to Teruhisa Tanabe.

16 recordsLinked to original sources
PubMed2006

Heavy ion radiation up-regulates Cx43 and ameliorates arrhythmogenic substrates in hearts after myocardial infarction.

OBJECTIVE: Radiation has been shown to enhance intercellular communication in the skin and lungs through an increase of connexin43 (Cx43) expression. If analogous Cx43 up-regulation is induced in the diseased heart, it would provide a new perspective in radiation therapy for arrhythmias. The aim of the present study is to test this hypothesis. METHODS: Non-transmural myocardial infarction (MI) was created in 24 rabbits by microsphere injection into the coronary arteries. Twenty-four rabbits without MI were used as controls. Targeted external heavy ion beam irradiation (THIR; 15 Gy) was applied 2 weeks after MI with an accelerator (HIMAC, Chiba, Japan). RESULTS: The THIR was associated with an increase of Cx43 mRNA and protein levels in the left ventricle in control as well as in MI rabbits. THIR also increased lateralization of Cx43, which was no longer colocalized with cadherins. In MI hearts, immunoreactive Cx43 signals were reduced in the peri-infarct zone, and the reduction was reversed by THIR. In-vivo epicardial potential mapping on the free wall (64 unipolar electrodes to cover 7 x 7 mm) in MI hearts revealed reduced conduction velocity, whereas dispersion of the activation-recovery interval (ARI) was increased compared with controls, and these changes were reversed by THIR. The vulnerability for ventricular tachyarrhythmias (VT/VF), which was estimated by programmed stimulation, was increased in MI hearts, and this increased vulnerability to arrhythmias was reversed by THIR. CONCLUSIONS: THIR increases Cx43 expression, improves the conductivity, decreases the spatial heterogeneity of repolarization, and reduces the vulnerability of rabbit hearts to ventricular arrhythmias after MI. THIR could have an antiarrhythmic potential through an improvement of electrical coupling.

Animals↗
PubMed2006

Nifekalant hydrochloride administration during cardiopulmonary resuscitation improves the transmural dispersion of myocardial repolarization: experimental study in a canine model of cardiopulmonary arrest.

BACKGROUND: Because nifekalant hydrochloride (NIF) displayed a superior defibrillating effect on ventricular tachycardia/fibrillation (VT/VF) in cardiopulmonary arrest (CPA) patients, despite some QT prolongation, its effect on transmural dispersion of repolarization (TDR) in the left ventricle (LV) in an animal model of CPA was investigated. METHODS AND RESULTS: Eight beagle dogs were created with a myocardial infarction under anesthesia, and then VT/VF induction by continuous stimulation and cardiopulmonary resuscitation (CPR) were repeated. NIF (0.3 mg/kg) was administered under acidotic conditions (pH 7.26). The QTc interval measured by Y-lead ECG showed no significant prolongation before and after NIF. The activation recovery interval (ARI) measured by 64-lead LV surface mapping showed minimum ARI prolongation (40%) by NIF without maximum ARI prolongation, and as a result the ARI dispersion decreased by 67%. The repolarization time (RPT) with the plunge electrode showed 13-19% prolongation in the subendocardium and subepicardium with CPR, but NIF prolonged the RPT in the middle layer alone (17%), and as a result Plunge-TDR decreased by 82% (n=8, p<0.05). CONCLUSIONS: Administration of NIF during CPR decreased the TDR by RPT prolongation selectively in the middle layer. Because the subendocardial and subepicardial RPTs after CPR were already prolonged before NIF administration, it may have been the reason why the QT-prolonging effect of NIF was not reflected in the body surface ECG.

Animals↗
PubMed2006

Can nifekalant hydrochloride be used as a first-line drug for cardiopulmonary arrest (CPA)? : comparative study of out-of-hospital CPA with acidosis and in-hospital CPA without acidosis.

BACKGROUND: Early defibrillation of ventricular tachycardia and fibrillation (VT/VF) is an urgent and most important method of resuscitation for survival in cardiopulmonary arrest (CPA). We have previously reported that nifekalant (NIF), a specific I(Kr) blocker developed in Japan, is effective for lidocaine (LID) resistant VT/VF in out-of-hospital CPA (OHCPA). However, little is known about the differences in the effect of NIF on OHCPA with acidosis and in-hospital CPA (IHCPA) without acidosis. METHODS AND RESULTS: The present study enrolled 91 cases of DC shock resistant VT/VF among 892 cases of CPA that occurred between June 2000 and May 2003. NIF was used (0.15-0.3 mg/kg) after LID according to the cardiopulmonary resuscitation (CPR) algorithm of Tokai University. The defibrillation rate was higher in the NIF group for both OHCPA and IHCPA than for LID alone, and the VT/VF rate reduction effect could be maintained even with acidosis. However, sinus bradycardia in OHCPA, and torsades de pointes in IHCPA were occasionally observed. These differences in adverse effects might be related to the amount of epinephrine, serum potassium levels, serum pH, and interaction with LID. CONCLUSIONS: NIF had a favorable defibrillating effect in both CPA groups, and it shows promise of becoming a first-line drug for CPR.

Acidosis↗
PubMed2005

Hypertensive patients with carotid artery plaque exhibit increased platelet aggregability.

BACKGROUND: Platelets play an important role in myocardial infarction and ischemic stroke events, but whether platelet aggregability is related to early stage arteriosclerosis remains unclear. METHODS: We used a novel platelet counting system which makes it possible to detect spontaneous platelet aggregation, to evaluate the relationship between platelet aggregability and carotid artery arteriosclerosis in 125 outpatients with primary hypertension (46-73 years old: 65 men, 60 women). All subjects underwent carotid artery ultrasonography to determine whether plaque was present and to estimate intima-media thickness. RESULTS: Patients with carotid artery plaques (Plaque(+), n=63) were older and had higher systolic blood pressures than patients without plaques (Plaque(-), n=62), but no significant differences in sex, body mass index, diastolic blood pressure, plasma concentrations of glucose, total cholesterol, triglyceride, lipoprotein cholesterol, fibrinogen or the platelet count in whole blood were observed between Plaque(+) and Plaque(-) groups. Plaque(+) subjects showed greater spontaneous platelet aggregability and platelet aggregation induced by 2 microM or 0.5 microM of ADP or 0.3 microM of epinephrine than the Plaque(-) group. When age and systolic blood pressure were matched (n=52 in both groups), the Plaque(+) subjects exhibited greater platelet aggregability than the Plaque(-) subjects. Platelet aggregation induced by 2 microM of ADP showed statistical significant positive correlation coefficients with age, HbA1c and diastolic blood pressure. CONCLUSION: Our results indicate that hypertensive patients with carotid artery plaque have increased platelet aggregability. A prospective study is recommended to clarify whether this increase in platelet aggregability promotes the progression of arteriosclerosis.

Adenosine Diphosphate↗
PubMed2005

Combined effects of nifekalant and lidocaine on the spiral-type re-entry in a perfused 2-dimensional layer of rabbit ventricular myocardium.

BACKGROUND: Spiral re-entry plays the principal role in the genesis of ventricular tachycardia and ventricular fibrillation (VT/VF). The specific I(Kr) blocker, nifekakant (NIF) has, often in combination with lidocaine (LID), recently been used in Japan to prevent recurrent VT/VF, but the combined effects of these drugs on spiral re-entry had never been investigated. METHODS AND RESULTS: A ventricular epicardial sheet was obtained from 13 Langendorff-perfused rabbit hearts by means of a cryoprocedure, and epicardial excitations were analyzed with a high-resolution optical mapping system. Nifekakant (0.5 micromol/L) caused significant prolongation of action potential duration (APD) and LID (3 micromol/L) attenuated the APD prolongation without affecting the conduction velocity. VT were induced in 6 hearts by cross-field stimulation, and single- or double-loop spirals circulating around variable functional block lines were visualized during the VT. Nifekakant reduced VT cycle length and caused early termination in association with destabilization of the spiral dynamics (prolongation of functional block line, frequent local conduction block, and extensive meandering). These modifications of spiral-type re-entrant VT by NIF were prevented by addition of LID. CONCLUSIONS: The effects of NIF on the spiral excitations are reversed by LID. This interaction should be taken into account when these drugs are used in combination to treat VT/VF.

Animals↗
PubMed2005

Effectiveness of short-term treatment with nocturnal oxygen therapy for central sleep apnea in patients with congestive heart failure.

OBJECTIVES: To evaluate the short term effects of inhalation of oxygen at night in 51 patients with congestive heart failure (CHF) and sleep apnea syndrome (SAS). METHODS: Fifty-one patients with stable CHF (31 males, 20 females, mean age 79.0 +/- 11.9 years; brain natriuretic peptide level of > 100 pg/ml) were evaluated between September 2003 and August 2004, using a Morpheus monitor. The complication rate of SAS in patients with CHF was assessed and apnea hypopnea index, oxygen desaturation index 3%, heart rate, and autonomic nerve activity under room air compared to supplemental O2 (2 l/min) over two consecutive nights. RESULTS: Thirty-eight (75%)of the CHF patients had SAS. Of these SAS patients, 49% suffered from central SAS and 51% had obstructive SAS. Apnea hypopnea index and oxygen desaturation index 3% improved remarkably with supplemental oxygen (p < 0.001), in particular, the central SAS group demonstrated prominent improvement (p < 0.001). Obstructive SAS patients exhibited no significant changes (p = 0.3356), but tended to exacerbate the episodes of sleep apnea. Total heart rate was decreased (p = 0.0079). Nevertheless, heart rate variability analysis showed little effect of nocturnal oxygen therapy on the autonomic nervous system during sleeping. CONCLUSIONS: Nocturnal oxygen therapy improved the number of sleep apnea episodes and decreased total heart rate during sleep time for the CHF patients with central SAS, despite little influence on the autonomic nervous system, based upon assessment of heart rate variability. Obstructive SAS might exacerbate the episodes of sleep apnea.

Aged↗
PubMed2005

Clinical profile and prognosis of hospitalized patients with congestive heart failure in Isehara, Japan.

Since the clinical profile and prognosis of heart failure depending on time of the study performed, regional characteristics of background population and different race, we attempted to evaluate the prognosis of symptoms and life expectancy of Japanese patients with heart failure. We evaluated the clinical profiles and prognoses of 1,015 consecutive patients with congestive heart failure (CHF) for whom hospitalization was required. A total of 1,015 consecutive CHF patients (584 males and 431 females) were enrolled in this study, however the total number of events investigated was 1,409. Of these patients, survival was confirmed in 413 patients, death was confirmed in 299 patients, and the prognoses of 303 patients remained unknown due to transfer to other hospitals or for some other reasons. The mean age on admission was 68.4 +/- 14.9 years. In both males and females, the peak age at the onset of CHF was in the seventies, and for patients in their eighties, the number of female patients with CHF was larger than that of male patients. Major underlying heart diseases consisted of ischemic heart disease (34%), valvular heart disease (22%), dilated cardiomyopathy (11%), and hypertension (10%). Most CHF patients who had dilated cardiomyopathy as an underlying disease were hospitalized several times, and 45% of them were hospitalized 3 times or more. The life expectancy of patients with CHF caused by ischemic heart disease was the poorest, and their 5-year and 10-year survival rates were 55% and 38%, respectively. Similarly, 5-year and 10-year survival rates of patients with CHF caused by valvular heart disease, hypertension, and dilated cardiomyopathy were 62% and 44%, 58% and 53%, and 70% and 65%, respectively. In 299 deceased patients, the mean age at death was 72.2 +/- 13.9 years. In all these deceased patients, direct causes of death were sudden death (16.1%), CHF (42.2%), others (31.4%), and unknown (10.4%). The frequency of sudden death was highest (25%) in patients with CHF caused by dilated cardiomyopathy, followed by those with CHF caused by valvular heart disease (18%) and those with CHF caused by ischemic heart disease (17.5%). In addition, the frequency of death from CHF was highest (60%) in those with CHF caused by dilated cardiomyopathy, followed by those with CHF caused by ischemic heart disease (49.2%).

Adolescent↗
PubMed2005

A case of familial hypercholesterolemia; secession from LDL-apheresis by the drug treatment with potent statin and resin.

Low density lipoprotein (LDL)-apheresis is a useful tool for the treatment of familial hypercholesterolemia (FH) with coronary artery disease (CAD). However, it gives economic, physical and mental burdens for the patients. We reports a case of FH in whom LDL-apheresis treatment was seceded with drug treatment with a potent statin and bile acid-sequestering resin. A 54-year-old woman was admitted for evaluation of atherosclerotic lesion after 4 years of LDL-apheresis and 1 year of drug medication with a potent statin, atorvastatin and resin, cholestimide with coronary angiography. She had been diagnosed as heterozygous FH when she was 46 years old. Oral medication was initiated at the outpatient clinic. LDL-cholesterol (C) level was not successfully controlled despite the administration of a statin, pravastatin, a fibrate, clinofibrate and probucol at maximum doses Concomitantly. Therefore, as combination therapy, LDL-apheresis was introduced in May 1997. However, the patient strongly complained of the economic, physical, and mental burdens of LDL-apheresis and requested discontinuation of apheresis. Therefore, LDL-apheresis was discontinued in July 2000, and oral medication was subsequently changed to a combination of atorvastatin and cholestimide, resulting in successful control of serum LDL-C level by oral medication alone. We compared coronary arteriographic findings between 1997 and 2001. No advancement of lesions was observed. We think that strong drug treatment can secede from the LDL-apheresis for treatment of patients with FH.

Achilles Tendon↗
PubMed2005

The physics of guiding catheters for the left coronary artery in transfemoral and transradial interventions.

BACKGROUND: The backup force of a guiding catheter is important for successful percutaneous coronary intervention (PCI), however, no theory has been proposed thus far regarding the factors involved in its generation. METHODS AND RESULTS: The backup force of guiding catheters was measured in an arterial tree model. In vitro modeling showed that larger-sized guiding catheters had greater backup force (8 Fr > 7 Fr > 6 Fr). Comparing the backup force between transfemoral (TFI) and transradial interventions (TRI), it was found to be 60% greater in TFI with a Judkins L (JL) catheter, and 8% greater in TFI with a backup (EBU/XB) type catheter. However, the Ikari L (IL) catheter generated a similar backup force between TRI and TFI. In TRI, the Ikari guiding catheter showed the greatest backup force, especially in the power position (power position of IL4 > IL4 > backup type 3.5 > deep engagement of JL4 > JL3.5 > JL4). These findings were associated with the angle of the catheter on the reverse side of the aorta. We then constructed several catheters with varying contact lengths. In vitro modeling showed that a longer contact area increased the backup force. CONCLUSIONS: The present model showed that three factors were associated with backup force: (1) catheter size; (2) angle on the reverse side of the aorta; and (3) contact area. The Ikari guiding catheter comprises all of the preferable factors in TRI.

Angioplasty, Balloon, Coronary↗
PubMed2005

Detection of right to left shunting through a patent foramen ovale in Japanese patients with ischemic stroke by transesophageal echocardiography using a standardized Valsalva maneuver.

We attempted to clarify the usefulness of transesophageal echocardiography performed using a standardized Valsalva maneuver to detect the presence of a patent foramen ovale in Japanese patients with ischemic stroke. Four hundred ninety six patients with ischemic stroke who were admitted to the Yokohama City Brain and Stroke Center between September 1999 and February 2002 were enrolled for the study. All the enrolled patients underwent transesophageal echocardiography with contrast injection and color Doppler imaging. During the procedure, a standardized Valsalva maneuver was performed to induce right to left shunting through a patent foramen ovale. Other related structural abnormalities, such as atrial septal aneurysm and the Chiari network anomaly, were also detected by the test. Transesophageal echocardiography without the Valsalva maneuver revealed a functional right to left communication in only 8.2% of the ischemic stroke patients, whereas the procedure conducted using a standardized Valsalva maneuver to provoke shunting revealed a patent foramen ovale in 15.3% of the patients. The presence of an atrial septal aneurysm or the Chiari network anomaly was not sensitive or specific enough to predict the presence of a patent foramen ovale as diagnosed by transesophageal echocardiography using the standardized Valsalva maneuver. Our results suggest that the standardized Valsalva maneuver is a safe and useful technique to detect the presence of a patent foramen ovale, which is potentially known to be associated with paradoxical embolism.

Aged↗
PubMed2003

Possible contribution of acetylamrinone and its enhancing effects on platelet aggregation under shear stress conditions in the onset of thrombocytopenia in patients treated with amrinone.

BACKGROUND: Thrombocytopenia is recognized as one of the most common complications when the patients with severe heart failure are treated with cardiotropic phosphodiesterase (PDE)-3 inhibitors. To understand the mechanism of the onset of this complication, we focused on the effects of various PDE-3 inhibitors and its stable metabolite of acetylamrinone on platelet aggregation occurring under physiological shear stress conditions. METHOD: Blood specimens were obtained from eight apparently healthy adult donors. Platelet-rich plasma was separated after anticoagulation by citrate. The effects of PDE-3 inhibitors of amrinone and olprinone, as well as the stable metabolite of the former of acetylamrinone, on platelet aggregation induced by its exposure to a shear rate of 1200 and 10,800 s(-1) were determined by optically modified cone-plate viscometer. RESULTS: Both olprinone and amrinone inhibited platelet aggregation at 10,800 s(-1) in a dose-dependent manner with the IC(50) value of 14 +/- 1 and 61 +/- 8 microM (mean +/- S.D.), respectively, while amrinone significantly inhibited platelet aggregation at 1200 s(-1) only at highest concentration tested (100 microM). Contrary to the effects shown with PDE-3 inhibitors, acetylamrinone did not inhibit platelet aggregation at all. Moreover, it even enhanced the aggregation at 1200 s(-1) when used with 5 microM. CONCLUSIONS: Our results demonstrate possible contribution of the enhancing effects of acetylamrinone on platelet aggregation occurring under blood flow conditions, which reduced the platelet count when occurring in real circulation, to the higher incidence of thrombocytopenia in patients treated with amrinone.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2003

[Efficacy of Nifekalant hydrochloride for life-threatening ventricular tachyarrhythmias in patients with resistance to lidocaine: a study of patients with out-of-hospital cardiac arrest].

OBJECTIVES: Class I antiarrhythmic agents are not always effective in the treatment of life-threatening ventricular tachycardia/ventricular fibrillation (VT/VF) especially in patients with cardiopulmonary arrest. Nifekalant hydrochloride(NIF) is a novel class III antiarrhythmic agent for malignant VT/VF. This study prospectively evaluated NIF efficacy for life-threatening VT/VF observed after cardiopulmonary arrest. METHODS: Thirty-two of 145 patients who were transferred to the emergency room in Tokai University Hospital showed VT/VF after resuscitation from cardiopulmonary arrest from June 2000 to March 2001. These 32 patients were treated with 12 mg (mean) epinephrine and 1.0-2.0 mg/kg lidocaine following direct current application(200 to 360J), and then classified into two groups. Eleven patients received intravenous 0.15 to 0.3 mg/kg NIF followed by intravenous infusion of 0.3 to 0.4 mg/kg/hr NIF(NIF group). The other 21 patients received 1.0 to 2.0 mg/kg of lidocaine(non-NIF group). RESULTS: Sinus rhythm was restored in the nine patients(82%) in the NIF group but only four patients (19%) in the non-NIF group. QTc was not prolonged(0.45 +/- 0.04 sec, n = 9) and no torsades de pointes was observed in the NIF group. Two patients survived but the remaining nine patients died in the NIF group. Five patients died of cardiac standstill following sinus bradycardia and repeated sinus arrest within 2 to 27 hr after admission, two patients died of sudden cardiac arrest from sinus rhythm, and two patients died of persistent VT/VF. In contrast, all 21 patients in the non-NIF group died. Seventeen patients died of persistent VT/VF before hospitalization, one patient died of recurrent VT/VF, and three patients died of cardiac standstill following sinus bradycardia. CONCLUSIONS: NIF effectively suppresses VT/VF which is refractory to direct current shock in patients with cardiopulmonary arrest. However, NIF may rather worsen electrophysiological function in the sinus node after administration of high doses of epinephrine, and may induce sinus bradycardia and/or sinus arrest. Careful observation, such as monitoring of electrocardiography and blood pressure and temporary cardiac pacemaker use, is needed to prevent death in patients surviving after cardiopulmonary arrest if NIF is administered following high dose epinephrine infusion.

Adult↗
PubMed2002

Shear-induced von Willebrand factor-mediated platelet surface translocation of the CD40 ligand.

BACKGROUND: Platelets, which can adhere to damaged vascular surfaces and release bioactive substances upon activation, may play important roles in regulating local inflammatory responses. We focused on the surface translocation of CD40 ligand (CD40L) molecules when the platelets are exposed to a high shear stress. METHOD: Blood specimens were obtained from eight apparently healthy adult donors. The number of CD40L molecules appearing on the surface of platelets after exposure of platelet-rich plasma to a shear rate of 10,800 s(-1) was determined by quantitative flow cytometry. RESULTS: The number of anti-CD40L IgG molecules bound per platelet increased from 15+/-80/platelet before to 355+/-122/platelet after exposure of the platelets to a shear rate of 10,800 s(-1) (p<0.01), but not after their exposure to the relatively low shear rate of 1200 s(-1). This shear-induced platelet surface translocation of CD40L, mediated by the von Willebrand factor (VWF)-GP Ibalpha interaction, was enhanced in the presence of a low concentration of epinephrine (100 nM), which by itself, however, could not cause platelet activation. Our results demonstrate that fluid force induces the appearance of CD40L on the surface of platelets, and also that this phenomenon is enhanced in the presence of a low concentration of epinephrine, corresponding to that released by sympathetic stimulation.

Adult↗
PubMed2002

[Significance of electrocardiographic QRS width in patients with congestive heart failure: a marker for biventricular pacing].

OBJECTIVES: Biventricular pacing may be valuable for the treatment of patients with intractable heart failure, but how many patients in Japan would benefit from this type of therapy remains uncertain. This study investigated the incidence of intraventricular conduction delay in the electrocardiogram(ECG) as a marker of the need for biventricular pacing, as well as the underlying etiology of heart failure in patients admitted with congestive heart failure. METHODS: Patients with heart failure admitted to the Tokai University Hospital from January 1990 to September 2000 were studied retrospectively. The distribution of age, sex and underlying diseases, and that of the rhythm and the QRS width in ECG recordings were analyzed. Patients with a QRS width of over 121 msec in the ECG were classified as the 'wide QRS' group. RESULTS: Of a series of 1,200 consecutive patients with heart failure, 872 patients, 499 males and 373 females (mean age 67.9 +/- 13.9 years) were admitted to the hospital and 71 had 'wide QRS' by ECG. Among those in the 'wide QRS' group, 37% had ischemic heart disease and 14% had dilated cardiomyopathy. The widest QRS complexes were encountered in patients with dilated cardiomyopathy and the largest number of wide QRS complexes was encountered in patients with ischemic heart disease. CONCLUSIONS: The most frequent causes of heart failure among patients considered suitable for biventricular pacing were ischemic heart disease and dilated cardiomyopathy, which is consistent with previous reports. Compared with the statistics reported from western countries, the incidence of ischemic heart disease and the incidence of intraventricular conduction delay were lower in Japanese patients with heart failure. The incidence of intraventricular conduction delay among patients with heart failure was 8.6%. Therefore, fewer patients need biventricular pacing in Japan than in western countries. Nevertheless, patients with heart failure resistant to other therapies might still benefit from this type of therapy.

Adult↗