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Biomedical subjects

A Nishikado

Publications and source records attributed to A Nishikado.

32 records · Page 2Linked to original sources
PubMed1993

Catheter ablation therapy in a case with WPW syndrome complicated by multiple tachyarrhythmias.

WPW syndrome is of importance because of the frequent association of tachyarrhythmias. However, its complication by 3 or more different tachyarrhythmias simultaneously is rare. This paper reports a case of WPW syndrome complicated by paroxysmal atrial fibrillation, atrial flutter, and 2 types of atrioventricular reentrant tachycardia. The tachyarrhythmias could be cured by cauterizing the accessory pathway using catheter ablation with radiofrequency electric current. A 30-year-old man visited to a local physician with an episode of tachycardia which failed to resolve, and a diagnosis of WPW syndrome associated with paroxysmal atrial fibrillation was made. The patient was referred to our hospital for further examination and treatment, and electrophysiological study was performed. During the examination, 2 types of atrioventricular reentrant tachycardia with different heart rates were induced, as well as atrial fibrillation and 2:1 atrial flutter. The presence of a left-sided accessory atrioventricular pathway was confirmed by coronary sinus mapping, and the following day catheter ablation was performed and the accessory pathway was cauterized. Subsequently, the delta wave disappeared from the ECG and no additional episodes of tachycardia occurred. Catheter ablation is still undergoing research as a therapeutic modality. However, because the ablation technique entails little invasion or risk, and is economical, it may well become a mainstream treatment for tachycardia in patients with WPW syndrome in the future.

Adult↗
PubMed1992

Two sudden death cases of idiopathic ventricular tachycardia.

It is said that the prognosis of idiopathic ventricular tachycardia (IVT) without organic heart disease is good in general. In this paper, two sudden death cases of IVT are reported. The first case was a 44-year-old male, who was referred to our hospital for further examination and treatment of ventricular tachycardia. Echocardiography did not show obvious organic heart disease. After the patient was diagnosed with IVT, he was given drug therapy at the outpatient clinic. However, about six months later, he died suddenly while playing mahjong late at night. The second case was a 17-year-old male. He was also referred to our hospital by another hospital after being diagnosed with ventricular tachycardia. A diagnosis of IVT was made, for which he was given drug therapy at outpatient clinic. However, the patient discontinued receiving the drug therapy. The patient died suddenly about 3 months after discontinuation of the therapy. Some idiopathic ventricular tachycardia cases have poor prognosis like the present ones. It was considered necessary to thoroughly control and guide patients with their daily life and monitor them carefully about the ingestion of anti-arrhythmic agents.

Adolescent↗
PubMed1992

A case of concealed WPW syndrome with three different reciprocal tachycardias due to triple AV nodal pathways.

Triple atrioventricular nodal pathways (TAVNP) occur occasionally, but it is rare for them to produce more than two different tachycardias. Here we report a case of concealed WPW syndrome with three different tachycardias. During electrophysiologic studies, three different reciprocal tachycardias were induced. Tachycardia #1 was characterized by a cycle length of 230 msec and an A'-H interval of 70 msec. For tachycardia #2, these parameters were 300 msec and 140 msec, while they were 370 msec and 200 msec for tachycardia #3. During all three tachycardias, the earliest atrial activity was observed in the left atrium. Ventriculoatrial conduction occurred following ventricular stimulation, and the earliest atrial activity was observed in the left atrium, indicating the existence of left-sided accessory pathway. Persistence of tachycardia for 15-30 min caused marked pulmonary congestion. The heart rate was very high (260 beats/min) during tachycardia #1, and the pulmonary arterial pressure rose to 40/30 mmHg, with the pulmonary arterial diastolic pressure remaining at about 30 mmHg throughout the tachycardia. It seems that the pulmonary venous pressure rises abnormally during paroxysmal supraventricular tachycardia with a very high heart rate and that pulmonary congestion can easily occur during a short period of tachycardia.

Electrocardiography↗
PubMed1991

Right atrial myxoma with hypervascularity demonstrated by selective coronary angiography.

Cardiac myxoma is the commonest primary cardiac tumor, however, the incidence of right atrial myxoma is very rare. We reported a 71-year-old man with a right atrial myxoma, whose main complaint was fever of unknown origin. Definite diagnosis was confirmed by echocardiography and cineangiocardiography. Venacavogram revealed huge mass which occupied greater part of right atrial cavity. Coronary angiogram revealed the feeding artery arising from left coronary circumflex artery and the sign of hypervascularity. Open heart surgery was performed, and a 4.9 x 4.0 x 3.8 cm tumor was found in the right atrial cavity. Pathological examination showed the findings of myxoma. Postoperative clinical course was uneventful.

Aged↗
PubMed1991

The efficacy of isoproterenol on quinidine induced torsade de pointes.

The efficacy of isoproterenol for torsade de pointes (TdP) was evaluated in 60 dogs. TdP was induced in 34 of 60 dogs (56.7%) after the administration of quinidine sulfate (30 mg/kg). The electrophysiologic effect of isoproterenol (0.5 micrograms/min) was studied in 9 dogs with quinidine induced TdP. Isoproterenol significantly shortened basic cycle length, corrected QT interval, effective refractory period (ERP) and dispersion of ERP and increased ERP/QT. Isoproterenol prevented the occurrence of TdP in all dogs. These findings suggest that isoproterenol decreases the dispersion of ventricular refractoriness and may be useful in the treatment of drug induced TdP.

Animals↗
PubMed1991

[Efficacy of isoproterenol, magnesium sulfate and verapamil for torsade de pointes].

The efficacy of isoproterenol, MgSO4 and verapamil for torsade de pointes was evaluated in 60 dogs. Torsade de pointes was induced in 28 out of 60 dogs (46.7%) by ventricular stimulation after administration of quinidine sulfate (30 mg/kg). The electrophysiologic effect of isoproterenol (0.5 micrograms/min drip infusion) was studied in 9 dogs with torsade de pointes, in 9 dogs with MgSO4 (30 mg/kg), and in 10 dogs with verapamil (0.1 mg/kg bolus injection followed by 0.01 mg/kg/min drip infusion). If the first dose of these drugs was ineffective, ventricular stimulation was performed after the additional administration of the same dose. Isoproterenol significantly decreased QTc, ERP and dispersion of ERP but increased ERP/QT. MgSO4 significantly increased ERP and ERP/QT, however dispersion of ERP did not change. Verapamil induced no electrophysiologic changes in ventricular refractions . Isoproterenol prevented the occurrence of torsade de pointes in all dogs (100%), MgSO4 in 7 of 9 dogs (77.8%, 30 mg/kg in three and 60 mg/kg in four) and verapamil in 4 of 10 dogs (40%, 0.1 mg/kg in two and 0.2 mg/kg in two). These findings suggest that isoproterenol and MgSO4 increased ERP/QT, showing one of their antiarrhythmic effects. It also shows that isoproterenol and MgSO4 may be useful in the treatment of torsade de pointes.

Animals↗
PubMed1990

Effect of magnesium sulfate on ventricular refractoriness and its efficacy for torsade de pointes.

The effect of magnesium sulfate on ventricular refractoriness and its efficacy for torsade de pointes (TdP) were studied in nineteen dogs. After the administration of quinidine sulfate (30 mg/kg), TdP was induced by ventricular pacing in ten of 19 dogs (52.6%), polymorphic ventricular tachycardia in seven (36.8%), ventricular fibrillation in two (10.5%). Quinidine sulfate caused significant increases in QTc interval, ventricular effective refractory period (ERP) and dispersion of ERP(dERP), and decrease in ERP/QT. Magnesium sulfate significantly increased ERP (p less than 0.01), but it did not change QT interval, resulting in significant increasing of ERP/QT (0.41 +/- 0.05 to 0.61 +/- 0.05, p less than 0.01). It decreased dERP but not significantly. Magnesium sulfate prevented the induction of TdP in eight of 10 dogs (80.0%) (30 mg/kg in four and 60 mg/kg in four). In conclusion, magnesium sulfate has value as first aid therapy for drug-induced TdP. If patients have ischemic heart disease or hypertension, we recommend infusion of magnesium for the initial therapy of TdP.

Animals↗
PubMed1990

Significance of T wave abnormality in hypertension studied by spatial velocity electrocardiogram and vectorcardiogram.

The ST-T wave abnormality in hypertension has been considered to be an indicator of poor prognosis, but its precise pathophysiological significance remains unclear. The present study was aimed to correlate the electrocardiographic (ECG) change in T wave and left ventricular characteristics studied by echocardiogram. The T wave abnormality in the ECG represented hypertrophy of the left ventricle or abnormality of systolic function, but it was difficult to differentiate either of them by conventional ECG. It was shown in this study that the anterior displacement of the vectorcardiographic T loop was related to the ventricular hypertrophy and that the abnormal shape or inscription of the T loop was more closely related to the ventricular dysfunction rather than hypertrophy. These results suggested that the vectorcardiogram and spatial velocity electrocardiogram were useful for analysis of the T wave abnormality and add important information in addition to the conventional electrocardiogram.

Aged↗
PubMed1989

Coronary arteriovenous fistula with vasospastic angina.

A 50-year-old man was admitted to our hospital because of chest pain. Twenty-four-hour ECG recording demonstrated ST-segment depression and elevation at the time of spontaneous angina. During treadmill exercise test, the patient developed chest pain with ST-segment depression in leads V4 to V6. After the administration of nifedipine (10 mg), the patient was able to reach up to the maximum predicted heart rate without anginal symptoms and ST-T changes. Coronary arteriogram demonstrated 50% stenosis at the proximal portion of the left anterior descending artery (LAD) and two small fistulas originated from LAD to pulmonary artery. Spasm was induced at the proximal portion of LAD by the hyperventilation. If patients with coronary arteriovenous fistula (CAVF) have symptoms, elective CAVF ligation has been recommended. However, this case suggests that coronary spasm could be one of the cause of angina pectoris in patients with CAVF. Elective CAVF ligation must be carefully indicated in CAVF patients with angina pectoris.

Angina Pectoris↗
PubMed1989

[Electrophysiological effects of magnesium sulfate on human conduction system].

Electrophysiological studies were performed to evaluate the effects of MgSO4 on human conduction system. Nine patients who received 20 mg/kg of MgSO4 did not show any significant changes in the electrophysiological parameters except for prolongations in the PR and AH intervals. After the infusion of 40 mg/kg of MgSO4 in eleven patients, sinus cycle length and corrected sinus node recovery time were increased but statistically insignificantly. Sinoatrial conduction time, the PR interval and AH interval were increased. The effective refractory period (ERP) of right atrium, ERP of atrioventricular node (AV node), ERP of right ventricule and ERP/QTc were increased significantly. These findings suggests that the antiarrhythmic effects of magnesium were due to (1) suppression of the functions of the sinus and AV nodes, and (2) shortening of the duration of the ventricular vulnerable period during the cardiac cycle and prevention of ventricular arrhythmias related reentry mechanism.

Adolescent↗
PubMed1989

[A case of anomalous origin of right coronary artery from the left sinus of Valsalva with ventricular aneurysm ventricular tachycardia and paroxysmal A-V block].

A 51-year old man was admitted to our hospital, because of syncope. During admission, he had three episodes of syncopal attack. During the episodes, monitor ECG showed two times of ventricular tachycardia and one of paroxysmal A-V block. The left ventriculogram showed dilatation of left ventricle with posterobasal aneurysm, anterobasal and apical hypokinesis. The left coronary artery was normal. The right coronary artery originated from the left sinus of Valsalva and passed through between aortic root and pulmonary trunks. There was no atherosclerotic lesions in both coronary arteries. Non-sustained ventricular tachycardia was induced by triple premature stimulations. The inverse relation between the coupling interval of premature stimulation and the echo interval was recognized. Lidocaine (50 mg IV), Flecainide (300 mg/day), Mexiletine (450 mg/day), and Aprindine (60 mg/day) prevented ventricular tachycardia. Rapid atrial pacing induced paroxysmal A-V block. Permanent pacemaker was implanted because of syncope due to paroxysmal A-V block and ventricular tachycardia was prevented by Aprindine. Recently, the case with anomalous origin of the coronary artery increased by the popularity of coronary angiography. But, this case considered to be rare because of complication with ventricular aneurysm and lethal arrhythmia (ventricular tachycardia and paroxysmal A-V block).

Coronary Vessel Anomalies↗