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Biomedical subjects

Akira Fujiki

Publications and source records attributed to Akira Fujiki.

27 records · Page 2Linked to original sources
PubMed2004

Complex atrial reentrant circuits evaluated by entrainment mapping using a multielectrode basket catheter.

Atrial tachycardias after open heart surgery sometimes have complex reentrant circuits. A patient with a dual-loop atrial reentrant circuit occurring after mitral valve replacement was evaluated by entrainment mapping with a basket catheter. The position of the catheter was adjusted to obtain atrial electrograms of the anterior and posterior septal areas, the crista terminalis, the free wall, and the tricuspid annular region. Entrainment mapping identified a dual-loop reentry consisting of one circuit around the tricuspid annulus and another around the septal atriotomy scar. The reentrant circuit around the septal incision was eliminated by ablating the area between the septal incision and the inferior vena cava, and the circuit around the tricuspid annulus was terminated with an additional linear ablation between the tricuspid annulus and the inferior vena cava. Entrainment mapping using a multielectrode basket catheter is very useful for identifying complex atrial reentrant circuits.

Catheter Ablation↗
PubMed2004

Maintenance of sinus rhythm and recovery of atrial mechanical function after cardioversion with bepridil or in combination with aprindine in long-lasting persistent atrial fibrillation.

BACKGROUND: The aim of this study was to evaluate pharmacological cardioversion of long-lasting persistent atrial fibrillation (AF) using bepridil in terms of recovery of atrial mechanical function and maintenance of sinus rhythm. Bepridil alone or in combination with aprindine is effective for termination of persistent AF. METHODS AND RESULTS: The study group comprised 38 consecutive patients (24 men, 58.8+/-9.3 years) with successful conversion of persistent AF lasting >1 month either pharmacologically (Group I) or electrically (Group II). Fast Fourier transform analysis of fibrillation waves was performed and fibrillation cycle length (FCL) was calculated from the peak frequency. In Group I, sinus rhythm was pharmacologically restored in 22 patients after an average 30 days (7-49 days) of bepridil administration, either alone (11) or in combination with oral aprindine (11); they were followed up while using the same drugs. In Group II, electrical conversion restored sinus rhythm in 16 patients, and they were followed up with conventional antiarrhythmic drugs other than bepridil and aprindine. After bepridil treatment FCL increased and became significantly longer in Group I than in Group II (190+/-39 vs 150+/-29 ms, p<0.001). Atrial peak velocity in transmitral flow within the first week after cardioversion was greater in Group I than in Group II (68+/-35 vs 32+/-20 cm/s, p<0.05). By Kaplan-Meier analysis, 83% of Group I patients were free of AF recurrence at the 12-month follow-up, compared with 36% in Group II (p<0.005). CONCLUSIONS: In patients with long-lasting AF, pharmacological conversion with bepridil alone or in combination with aprindine recovered atrial mechanical function better and maintained sinus rhythm longer than electrical conversion.

Anti-Arrhythmia Agents↗
PubMed2003

Usefulness and safety of bepridil in converting persistent atrial fibrillation to sinus rhythm.

The aim of this study was to investigate the efficacy and safety of bepridil (a multichannel blocker including several potassium channels) for conversion of long-lasting atrial fibrillation (AF). Bepridil restored sinus rhythm alone or in combination with aprindine in 69% of 32 patients with persistent AF lasting > or = 3 months. The time to conversion after starting bepridil was 30 +/- 12 days. An increase in fibrillation cycle length with bepridil was greater in responders (31 +/- 10%), but an increase in QTc did not differ between responders and nonresponders. Bepridil is effective and safe for terminating long-lasting persistent AF.

Anti-Arrhythmia Agents↗
PubMed2003

Proportion and prognosis of healthy people with coved or saddle-back type ST segment elevation in the right precordial leads during 10 years follow-up.

AIMS: The aim of this study was to investigate long-term proportion and prognosis of healthy subjects with right precordial ST segment elevation without family history of sudden death. METHODS AND RESULTS: We followed up electrocardiograms (ECGs) of 3339 healthy subjects (male/female 2646/693) who underwent periodical medical examination form 1992 to 2001 to determine the relationship between year-to-year changes of ST segment morphology and the risk of fatal arrhythmias. Inclusion criterion was defined as presenting either coved or saddle back type ST segment elevation (>0.2 mV) in the right precordial leads. The cumulative total subjects who showed Brugada-like ECG changes at least once throughout the follow-up period were 69 (male/female 67/2; age 47.9+/-8.9 years, 2.1% of total subjects). During a follow-up period, annual mean proportion of coved or saddle back type ST elevation in the right precordial leads was 1.22+/-0.23% (0.88-1.88%). The morphological pattern of ST segment elevation was saddle-back in 77.3+/-7.9% and coved in 22.7+/-7.9% of subjects. Throughout the follow-up period, 39 subjects (56.5%) showed changes in ST segment elevation pattern. Twenty-nine subjects (42.0%) showed normalization of ST segment elevation at least once. Sixty-nine subjects were followed for a period of one to 10 years (median 4 years, interquartile range 4-8 years). Only one subject with persistent saddle-back type ST elevation had episodes of ventricular fibrillation (VF). CONCLUSIONS: The average proportion of healthy subject who had coved or saddle-back type of ST elevation in the right precordial leads without family history of sudden death was 1.22% and the risk of fatal arrhythmias was low (1/393.5 subject-years).

Arrhythmias, Cardiac↗
PubMed2003

Role of fibrillation cycle length in spontaneous and drug-induced termination of human atrial fibrillation.

The aim of this study was to investigate the mechanism of spontaneous termination of atrial fibrillation (AF) by comparing it with drug-induced termination on the basis of changes in fibrillation cycle length (FCL). Fast Fourier transform analysis was carried out on the electrocardiogram (ECG) records of 27 patients with paroxysmal AF without organic heart disease. In 8 patients with drug-induced termination of AF, spectral analysis of the data from surface ECG lead V1 was performed before and after class I antiarrhythmic drug infusion for 10 min. In 19 patients with spontaneous termination of AF, the analysis used the Holter ECG recordings at 10 min before the spontaneous termination and at the termination. FCL was calculated from the peak frequency of each epoch and the mean FCL and the coefficient of variation (CV) of FCL were determined from the data of 20 epochs. In the 8 episodes of drug-induced AF termination, the mean FCL increased significantly with class I drugs (from 151+/-17 to 203+/-21 ms, p<0.001), whereas in the 19 episodes of spontaneous termination, the mean FCL and CV of FCL at termination did not differ from those at 10 min before the termination. Of the 19 episodes, 10 episodes terminating in the morning showed a significant increase in the FCL of the last epoch of the termination period (from 158 +/-22 to 172+/-17 ms, p<0.05). In the 9 episodes terminating in either the afternoon or the evening, the FCL of the last epoch did not change significantly. Although drug-induced termination of paroxysmal AF may depend on a gradual increase in FCL, the pattern of spontaneous termination may depend on the time of day. Spontaneous termination in the morning may be caused by an abrupt increase in FCL related to vagolytic autonomic balance.

Anti-Arrhythmia Agents↗
PubMed2002

Relation between transverse conduction capability and the anatomy of the crista terminalis in patients with atrial flutter and atrial fibrillation: analysis by intracardiac echocardiography.

Although crista terminalis (CT) has been identified as the barrier to transverse conduction during typical atrial flutter (AFL), the relation between transverse conduction capabilities and anatomy of the CT remains unclear. The aim of the study was to evaluate that relation using intracardiac echocardiography (ICE). Ten patients with typical AFL (group AFL), 7 patients with paroxysmal atrial fibrillation (PAF) (group AF) and 8 patients without PAF or AFL (group N) underwent electrophysiologic testing. Using ICE images, the maximum diameter of the short axis of the CT (dCT) was measured and mapping and pacing catheters were positioned precisely. From extrastimulation delivered 1-2 cm anteriorly (free wall) or posteriorly (posterior wall) to the CT, the effective refractory period (CT-ERP) was determined as the longest coupling interval that resulted in split potentials at the mapping catheter positioned along the CT, a finding consistent with a transverse conduction block at the CT. The dCT was greater in group AFL than in groups AF and N (5.0+/-0.8 vs 4.3 +/-0.7, p<0.05 and 4.2+/-0.4 mm, p<0.01, respectively). The CT-ERP was longer during pacing from the posterior wall than from the free wall (307+/-68 vs 266+/-29 ms, p<0.05) as a whole group. The CT-ERP for the posterior wall pacing was longer in group AFL than in group N (339+/-80 vs 255+/-13, p<0.05). CT-ERP did not correlate with dCT; however, dCT was greater in patients with split potentials at the CT than in patients without them (4.9 +/-0.8 vs 4.1+/-0.5 mm, p<0.05). Therefore, the transverse conduction block of CT was more likely to occur in a thick CT. A limited transverse conduction capability of the CT is related to its thickness and might contribute to the development of typical AFL.

Adult↗
PubMed2002

Effects of a novel class III antiarrhythmic agent, NIP-142, on canine atrial fibrillation and flutter.

The effects of a new benzopyran derivative, NIP-142, on atrial fibrillation (AF) and flutter (AFL) and on electrophysiological variables were studied in the dog. NIP-142 (3mg/kg) was administered intravenously to pentobarbital-anesthetized beagles during vagally-induced AF and during AFL induced after placement of an intercaval crush. Isolated canine atrial tissues were studied using standard microelectrode technique. NIP-142 terminated AF in 5 of 6 dogs after an increase in fibrillation cycle length (CL) and prevented reinitiation of AF in all 6 dogs. NIP-142 terminated AFL in all 6 dogs without any appreciable change in flutter CL, and prevented reinitiation of AFL in all 6 dogs. NIP-142 prolonged atrial effective refractory periods (11+/-5%, 3+/-3%, 12+/-3%, and 10+/-5% from the baseline value at basic CLs of 150, 200, 300, and 350ms, respectively) without changes in intraatrial conduction time. The prolongation of the atrial effective refractory period was greater in the presence of vagal stimulation. NIP-142 decreased action potential phase-1 notch and increased phase-2 plateau height without making any changes in the action potential duration, although it did reverse carbachol-induced shortening of the action potential duration. In conclusion, NIP-142 is effective in treating AFL and vagally-induced AF by prolonging atrial refractoriness.

Animals↗
PubMed2002

[Brugada syndrome occurring in an identical twin: a case report].

A 51-year-old man was admitted for evaluation of palpitation and syncope. Electrocardiography showed right bundle branch block with ST segment elevation. Intravenous administration of pilsicainide(50 mg) converted the saddle-back type into coved type ST elevation. Ventricular fibrillation was induced with double extrastimuli applied to the right ventricular outflow tract. His identical younger twin had neither symptoms nor abnormality by electrocardiography. Intravenous administration of pilsicainide(50 mg) induced no significant changes in the younger twin. Although SCN5A mutation is considered to be associated with Brugada syndrome, the present results suggest that the genetic factor is not the only factor responsible for the pathogenesis of Brugada syndrome.

Anti-Arrhythmia Agents↗