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Biomedical subjects

H Kasanuki

Publications and source records attributed to H Kasanuki.

At least 109 records · Page 6Linked to original sources
PubMed1993

[Congestive heart failure and arrhythmia].

About 40% of cardiac death in patients with congestive heart failure (CHF) has been reported to be due to ventricular tachyarrhythmia. Therefore, it is important to know how to treat ventricular arrhythmia associated with CHF. Recently, proarrhythmic effect and negative inotropic effect of antiarrhythmic drugs (class I agents), have been noted and class III agents, especially amiodarone is expected to have preventing effects for sudden death. Furthermore, drug therapy such as beta blocker and ACE inhibitor and implantable cardioverter-defibrillator has advanced.

Adrenergic beta-Antagonists↗
PubMed1993

[Determining factors of successful percutaneous transvenous mitral commissurotomy and eligible indications for the procedure].

The aim of this report is to investigate the factors which influence mean left atrial pressure (LAP) after percutaneous transvenous mitral commissurotomy (PTMC) and the characteristics of patients in whom PTMC is most effective. Fifty one patients with symptomatic mitral stenosis underwent PTMC. The patients included 8 males and 43 females, aged 26-66 years (mean age of 46). These patients were classified into two groups according to LAP after PTMC: 31 cases with LAP after PTMC of 12 mmHg or less (group A) and 20 cases with LAP after PTMC greater than 12 mmHg (group B). The patients of group A were younger (44 +/- 6 vs 48 +/- 6 years, p < 0.05), and had atrial fibrillation (af) less frequently (35 vs 65%, p < 0.05), and had mitral valve calcification less frequently (29 vs 65%, p < 0.01). Before PTMC, LAP (19 +/- 6 vs 23 +/- 5 mmHg, p < 0.01) was lower and mitral valve area (MVA) (0.95 +/- 0.24 vs 0.81 +/- 0.15 cm2, p < 0.05) larger in group A. Symptoms graded according to the New York Heart Association functional classification system were similar in both groups before PTMC. After the procedure, final MVA (1.79 +/- 0.69 vs 1.40 +/- 0.50 cm2, p < 0.05) was larger and systolic pulmonary artery pressure (32 +/- 9 vs 39 +/- 7 mmHg, p < 0.01) lower in group A. Mitral regurgitation > or = 3-grade tended to complicate more frequently (3 vs 20%, NS) in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Linkage analysis in a Japanese long QT syndrome family].

Romano-Ward syndrome is an autosomal dominant trait disease, which is characterized by QT prolongation and normal hearings and shows predisposal to sudden death from cardiac arrhythmia. Recently, Keating et al. reported that Harvey ras-1 locus (H-ras-1) was closely linked to long QT syndrome (LQTS), being located on the short arm of chromosome 11. In this study we have examined a three-generation Japanese family whose members had recurrent fainting with prolongation of the QT interval on electrocardiogram. Using the H-ras-1 probe as DNA marker, we could not determine that the H-ras-1 gene was linked to LQTS. LQTS seems to be a genetically heterogeneous disease. Further study is needed to clarify the chromosomal location of the LQTS.

Adult↗
PubMed1992

Background current in sino-atrial node cells of the rabbit heart.

1. The Ca2+ current, K+ current, hyperpolarization-activated current, Na(+)-K+ pump current and the Na(+)-Ca2+ exchange current were all blocked by appropriate blockers and the remaining time-independent currents were investigated in single pacemaker cells of the rabbit sino-atrial node using the whole-cell patch clamp technique. 2. Exchanging the bathing solution from Tris-hydroxymethyl-aminomethane hydrochloride (Tris) Na+ free to 150 mM-Na+ induced an inward current and the slope conductance of the current-voltage relationship increased from 0.45 +/- 0.18 to 0.87 +/- 0.33 nS (n = 71) at -50 mV. The remaining conductance in Tris Na(+)-free solution was essentially the same when Tris was substituted with tetraethylammonium (TEA) or N-methyl-D-glucamine (NMG). The current density of the Na(+)-dependent inward current obtained by subtracting the current in Tris Na(+)-free from that in 150 mM-Na+ solution was 0.73 +/- 0.21 pA/pF (n = 71) at -50 mV. We called this current the Na(+)-dependent background current. 3. The membrane conductance was reduced by lowering the temperature of the external solution from 36 to 23 degrees C. In Tris Na(+)-free solution, the temperature-sensitive component was outward at all potentials, whereas it showed a reversal potential at around -20 mV in 150 mM-Na+ solution. This reversal potential was interpreted as a sum of the Cs+ efflux and Na+ influx, by comparing the Na(+)-dependent inward currents obtained at 36 degrees C and those at 23 degrees C. 4. Divalent cations (2 mM-Ni2+, 1 mM-Ba2+ or 2 mM-Ca2+) reduced only the outward current in the Tris Na(+)-free solution, while in the 150 mM-Na+ solution, they reduced both the inward and outward components of the current which had a reversal potential of around -10 mV. 5. Amiloride depressed the membrane conductance in 150 mM-Na+, Cs+ or Rb+ external solution, though only at negative membrane potentials, which suggests amiloride has a voltage-dependent effect on the background current. 6. Removal of Cl- from the external solution or the addition of a Cl- channel blocker (4,4'-dinitrostilbene-2,2'-disulphonic acid disodium salt, DNDS) failed to affect the membrane conductance. 7. When the monovalent cation-dependent inward current was measured by subtracting the current in the Tris solution from those recorded in the various monovalent cation solutions, the current amplitude decreased in the order: Rb+ greater than K+ greater than Cs+ greater than Na+ greater than Li+, which suggests a poor cation selectivity of this current system.(ABSTRACT TRUNCATED AT 400 WORDS)

Amiloride↗
PubMed1992

Evaluation of proarrhythmic effect of antiarrhythmic drugs on ventricular tachycardia associated with congestive heart failure.

The usefulness and limitations of antiarrhythmic drugs in ventricular tachycardias (VT) associated with congestive heart failure remain uncertain. The purpose of this study is to evaluate the proarrhythmic effects of antiarrhythmic drugs in patients with refractory VT associated with left ventricular dysfunction using electrophysiologic study (EPS). Twenty-four patients with left ventricular dysfunction, defined by left ventricular ejection fraction (LVEF) lower than 40% using left ventriculography, were studied. The average LVEF was 29.5%. As for underlying heart disease, 14 had old myocardial infarction, 8 cases had dilated cardiomyopathy and 2 had aortic regurgitation. As a control to this group, 23 cases with underlying heart disease and LVEF higher than 40%, and 27 cases with no obvious heart disease were studied. We considered a drug to have proarrhythmic effects if 1) it decreased by one the number of stimuli needed to induce VT, 2) induced non-sustained VT in the control study which changed to induced sustained VT, 3) the sustained VT or ventricular fibrillation was newly induced, or 4) the induced sustained VT which was stopped by pacing in the control study changed to induced VT which could not be terminated by pacing and required DC shock. Proarrhythmic effects were recognized in 17 of 24 cases with left ventricular dysfunction. Of the 67 drug trials, proarrythmic effects were seen in 26. Proarrhythmias were observed in 9 of 23 cases (39.1%) with organic heart disease associated with LVEF higher than 40%. In 12 of 69 drug trials (17.4%) proarrhythmias were observed. Of 27 cases with no obvious heart disease 10 cases (37%) had proarrhythmias. In 14 of 130 drug trials (10.8%), proarrhythmias were recognized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Spatial distribution of late potentials assessed by signal-averaged body surface mapping.

In order to evaluate the spatial location of late potentials (LPs), we designed a new system for the body surface mapping of signal-averaged, filtered ECG using 45 thoracic unipolar leads (5 X 9 array). Signals from patients with old myocardial infarction (MI, N = 8), arrhythmogenic right ventricular dysplasia (N = 1) and dilated cardiomyopathy (N = 2) were amplified and passed through a digital bandpass filter (60-300Hz). Departure maps, LP isopotential maps, and LP30 area maps were generated and superimposed. The LP30 duration was determined as the section between the filtered QRS endpoints and points 30 msec before. Isopotential maps of the LPs showed distinct positive and negative regions. In 8 cases with MI, the extreme was related to the zones indicated by departure maps, and LP30 area maps also corresponded to the departure areas. Most importantly, the spatial distribution for the LP30 area map was different for each type of disease. In conclusion, body surface LP isopotential maps and LP30 area maps may provide useful information concerning the spatial distribution of LPs.

Arrhythmias, Cardiac↗