Biomedical subjects

Koichi Mizumaki

Publications and source records attributed to Koichi Mizumaki.

At least 19 recordsLinked to original sources

PubMed2006

Double potentials at successful catheter ablation site of left-sided retrograde accessory pathway: mitral isthmus block or conduction through coronary sinus musculature.

INTRODUCTION: We studied three patients who had orthodromic atrioventricular reentrant tachycardia (AVRT) using left lateral accessory pathway (AP), with difficulty in identifying the earliest site of retrograde atrial activation. METHODS AND RESULTS: Electrophysiological studies and radiofrequency ablation were performed in three patients with refractory AVRT (Case 1 was a 42-year-old woman, Cases 2 and 3 were a 52- and a 40-year-old man, respectively). During AVRT, a prolonged ventriculoatrial (VA) interval (100-180 ms) and nearly simultaneous excitation of both distal and proximal coronary sinus (CS) sites were observed. During both AVRT and ventricular pacing, double atrial potentials were recorded in all patients. Ablation of the mitral annular site showing double atrial potentials (with the first component being present just after the ventricular potential at the left lateral atrioventricular annulus) eliminated retrograde AP conduction. In Cases 1 and 2 the first component of the double potentials was atrial activation conducted through AP distal to mitral isthmus block and the second component was activation proximal to block that conducted turning around the left-sided pulmonary veins. In Case 3 the first component was CS musculature activation conducted through AP and the second component was left atrium activation via CS musculature. CONCLUSION: In AVRT that has a long VA interval and difficulty in identifying the earliest site of retrograde atrial activation, two different mechanisms existed (mitral isthmus block and conduction through CS musculature). Careful mapping of double atrial potentials and continuous VA activation at the left lateral mitral annulus is essential for determination of a successful ablation site.

Adult↗

PubMed2006

Pharmacological cardioversion of persistent atrial fibrillation with and without a history of drug-resistant paroxysmal atrial fibrillation.

BACKGROUND: Suppression by antiarrhythmic drugs of the maintenance mechanisms could convert persistent atrial fibrillation (AF) to sinus rhythm (SR). Whether a history of drug-resistant paroxysmal AF (PAF) would affect the outcome of pharmacological conversion of persistent AF by bepridil or in combination with aprindine was evaluated in the present study. METHODS AND RESULTS: The study group comprised 51 consecutive patients (24 men, 61+/-8 years) undergoing pharmacological conversion of persistent AF lasting >1 month. Drug-resistant PAF was defined as AF and at least 2 ineffective antiarrhythmic drugs for suppression of AF recurrence. Fast Fourier transform analysis of fibrillation waves was used to measure fibrillation cycle length (FCL) from the peak frequency. Fifteen patients had a history of drug-resistant PAF (Group I), and the remaining 36 did not (Group II) before diagnosis of persistent AF. Ten patients (67%) in Group I and 26 patients (72%) in Group II were restored to SR by bepridil alone or in combination with aprindine after 29+/-15 days of drug administration. Before conversion to SR, bepridil increased the FCL more in Group II than in Group I. During a 12-month follow-up period, 4 of 10 patients in Group I and 2 of 26 patients in Group II (p<0.01) had recurrence of persistent AF with bepridil alone or in combination with aprindine. CONCLUSIONS: A history of drug-resistant PAF does not affect the efficacy of pharmacological conversion by bepridil or in combination with aprindine. However, recurrence of AF was significantly higher in patients with such a history.

Anti-Arrhythmia Agents↗

PubMed2006

Bradycardia-dependent ECG changes in Brugada syndrome.

BACKGROUND: In patients with Brugada syndrome (BS), ventricular fibrillation (VF) occurs mainly during sleep; therefore, not only vagal activity but also bradycardia dependent changes in ECG may relate to the nighttime occurrence of VF. The present study aimed to examine the difference in bradycardia-dependent changes in the ECG of symptomatic and asymptomatic BS patients. METHODS AND RESULTS: Twenty-one patients with BS were categorized into symptomatic (n = 9) and asymptomatic (n = 12) groups. During the electrophysiologic study, the ECG changes were evaluated at RR intervals of 400, 600, 750, 1,000 and 1,100 ms during extrastimulation from the right atrium. The ST levels in V2, and the QT interval in both V2 and V5 were measured. Along with an increase in the RR interval from 400 to 1,100 ms, the ST levels in V2 increased in both groups; the increase did not differ between the 2 groups. In both leads V2 and V5, the prolongation of the QT interval along with an increase in the RR interval from 400 to 1,100 ms was significantly smaller and the QT intervals at an RR interval of 1,100 ms were significantly shorter in the symptomatic than in the asymptomatic group. CONCLUSIONS: In patients with BS, the ST elevation was augmented during bradycardia to a similar extent in both symptomatic and asymptomatic patients. However, a inhibited prolongation of the QT interval during bradycardia was characteristic of symptomatic patients. These unique repolarization dynamics could relate to the nighttime occurrence of VF during bradycardia in patients with BS.

Adult↗

PubMed2005

Repolarization dynamics in patients with idiopathic ventricular fibrillation: pharmacological therapy with bepridil and disopyramide.

The electrocardiographic parameters relating occurrence of ventricular fibrillation (VF) episodes in patients with idiopathic VF (IVF) are still unknown. The aim of this study was to clarify efficacy of pharmacological therapy in patients with IVF with respect to repolarization dynamics. The study group consisted of 8 men (age 43.6 +/- 9.1 years) with IVF (Brugada type 5 patients, prominent J wave in the inferior leads 3 patients) who had documented spontaneous episodes of VF, 7 of whom had implantable cardioverter defibrillators. The relation between QT and RR interval was analyzed from 24-hour Holter ECG using an automatic analyzing system before and after pharmacological therapy (bepridil 5 and disopyramide 3). From QT-RR linear regression lines, QT intervals were determined at RR intervals of 0.6 second [QT(0.6)], 1.0 second [QT(1.0)], and 1.2 seconds [QT(1.2)]. Pharmacological therapy increased the slope of QT-RR regression line from 0.105 +/- 0.020 to 0.144 +/- 0.037 (P < 0.05). Accordingly, QT(1.0) and QT(1.2) became longer after drug therapy [QT(1.0), 0.382 +/- 0.016 seconds vs 0.414 +/- 0.016 seconds (P < 0.01); QT(1.2), 0.403 +/- 0.017 seconds vs 0.442 +/- 0.021 seconds (P < 0.01)]. However, QT(0.6) did not change after drug administration. Before drug therapy the average episodes of VF were 5.5 +/- 5.8 (range 1 to 17) during the observation period of 19.3 +/- 17.6 months (range 6 to 60 months). After drug therapy, 6 patients had no episode of VF for 24 to 120 months (66.0 +/- 38.5 months). Two patients had a single episode of VF for 12- and 96-month follow-ups. Pharmacological therapy decreased the frequency of VF episodes in association with prolongation of QT intervals at slower heart rates. Not only J wave and ST elevation but also shorter QT intervals at slower heart rates may represent an electrophysiological substrate for development of VF episodes in these specific IVF patients.

Adult↗

PubMed2005

Enalapril preserves sinus node function in a canine atrial fibrillation model induced by rapid atrial pacing.

METHODS AND RESULTS: Seventeen beagles were pretreated with either placebo (group I, n = 9) or enalapril 1 mg/kg/day (group II, n = 8) and paced at 500/min from the right atrial appendage for 4 weeks. Every week, corrected sinus node recovery time (CSNRT) and sinus cycle length (SCL) were measured. Quantitative analysis of interstitial fibrosis (IF) and adipose tissue (AT) in the SN was performed with Masson's trichrome stain, and apoptosis of the sinus nodal cells were detected with terminal deoxynucleotidyl transferase nick end-labeling. In group I, rapid atrial pacing prolonged both CSNRT and SCL. After 4 weeks of pacing, CSNRT and SCL were significantly shorter in group II (CSNRT, 410 +/- 37 msec; SCL, 426 +/- 34 msec) than in group I (CSNRT, 717 +/- 52 msec, P < 0.005; SCL, 568 +/- 73 msec, P < 0.05). Both IF and AT of the SN were greater in group I (IF, 9.7 +/- 1.9%; AT, 32.6 +/- 5.9%) than in seven sham dogs (IF, 2.4 +/- 0.9%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05) and in group II dogs (IF, 4.0 +/- 2.0%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05). End-labeling assay was positive in three of nine dogs in group I, but negative in group II and sham dogs. CONCLUSIONS: Rapid atrial pacing impaired SN function through IF and AT of the SN. Enalapril prevented these pacing-induced degenerative changes and improved SN function.

Analysis of Variance↗

PubMed2005

Dynamic changes in the QT-R-R relationship during head-up tilt test in patients with vasovagal syncope.

BACKGROUND: QT interval is influenced by preceding R-R intervals and autonomic nervous tone. Changes in QT intervals during vasovagal reflex might reflect autonomic modulation of ventricular repolarization; however, this issue has not been fully elucidated. This study aimed to evaluate dynamic response of QT interval to transient changes in R-R interval during vasovagal syncope (VVS) induced by head-up tilt test. METHODS: Eighteen patients with VVS and 18 age-and sex-matched controls were studied. All patients with VVS had a positive mixed-type response to head-up tilt and all controls had a negative response. CM5-lead digital electrocardiogram (ECG) was recorded and QT intervals were analyzed using Holter ECG analyzer. Using scatter plots of consecutive QT and the preceding R-R intervals, QT-R-R relations during tilt-up and tilt-back or during vasovagal reflex were independently fitted to an exponential curve: QT (second) = A + B x exp[k x R-R (second)]. RESULTS: During the tilt-up, A, B, and k did not differ between patients with VVS and controls. During the tilt back, k showed equivalent positive value compared to the tilt-up (4.1 +/- 1.3 vs -4.6 +/- 0.9) in controls. However, k remained negative (-1.3 +/- 1.5) during vasovagal reflex in patients with VVS. In six patients, in whom metoprolol was effective in eliminating VVS, QT-R-R relationship during the tilt-back became similar to that in controls. CONCLUSIONS: In patients with VVS, hysteresis of the QT-R-R relation is similarly shown during tilt-up as in controls, whereas this hysteresis is no longer evident and failure of QT prolongation is observed during VVS.

Adrenergic beta-Antagonists↗

PubMed2004

Repolarization abnormality in idiopathic ventricular fibrillation: assessment using 24-hour QT-RR and QaT-RR relationships.

INTRODUCTION: We evaluated the characteristics of QT-RR and QaT (apex of T wave)-RR relationships in patients with idiopathic ventricular fibrillation (IVF) compared with control subjects. We hypothesized that IVF patients have unique repolarization dynamics related to a reduced fast Na current and a prominent transient outward current. METHODS AND RESULTS: The study group consisted of 9 men (age 47 +/- 10 years) with IVF (6 with Brugada type and 3 with non-Brugada type) who had experienced nocturnal episodes of VF. The control group consisted of 28 healthy age-matched men (age 44 +/- 12 years). The relationships between QT and RR intervals and between QaT and RR intervals were analyzed from 24-hour Holter ECG data using an automatic measurement system. Both QT and QaT at RR intervals of 0.6, 1.0, and 1.2 seconds were determined from QT-RR and QaT-RR linear regression lines. Both QT-RR and QaT-RR slopes were lower in the IVF group than in the control group (QT-RR: 0.092 +/- 0.023 vs 0.137 +/- 0.031, P < 0.001; QaT-RR: 0.109 +/- 0.025 vs 0.153 +/- 0.028, P < 0.001). QT at an RR interval of 0.6 second did not differ between two groups, but QT at RR intervals of either 1.0 or 1.2 seconds was significantly shorter in the IVF group than in the control group (RR 1.0 s: 0.384 +/- 0.018 vs 0.399 +/- 0.017, P < 0.05; RR 1.2 s: 0.402 +/- 0.019 vs 0.426 +/- 0.020, P < 0.01). QaT at RR intervals of either 1.0 or 1.2 seconds also was shorter in the IVF group (RR 1.0 s: 0.289 +/- 0.022 vs 0.312 +/- 0.021, P < 0.01; RR 1.2 s: 0.311 +/- 0.024 vs 0.343 +/- 0.024, P < 0.01). In four patients, oral administration of disopyramide (300 mg/day) was effective in suppressing VF episodes and increased slopes of QT-RR and QaT-RR relationships. CONCLUSION: IVF patients had lower slopes of QT-RR and QaT-RR regression lines and impaired prolongation of QT and QaT at longer RR intervals compared with control subjects. These unique repolarization dynamics may be related to the frequent occurrence of VF episodes at night.

Adult↗

PubMed2004

Entrainment mapping of dual-loop macroreentry in common atrial flutter: new insights into the atrial flutter circuit.

INTRODUCTION: The aim of this study was to determine using entrainment mapping whether the reentrant circuit of common type atrial flutter (AFL) is single loop or dual loop. METHODS AND RESULTS: In 12 consecutive patients with counterclockwise (CCW) AFL, entrainment mapping was performed with evaluation of atrial electrograms from the tricuspid annulus (TA) and the posterior right atrial (RA) area. We hypothesized that a dual-loop reentry could be surmised from "paradoxical delayed capture" of the proximal part of the circuit having a longer interval from the stimulus to the captured beat compared with the distal part of the circuit. In 6 of 12 patients with CCW AFL, during entrainment from the septal side of the posterior blocking line, the interval from the stimulus to the last captured beat was longer at the RA free wall than at the isthmus position. In these six patients with paradoxical delayed capture, flutter cycle length (FCL) was 227 +/- 12 ms and postpacing interval minus FCL was significantly shorter at the posterior blocking line than at the RA free wall (20 +/- 11 ms vs 48 +/- 33 ms, P < 0.05). In two of these patients, early breakthrough occurred at the lateral TA. A posterior block line was confirmed in all six patients in the sinus venosa area by intracardiac echocardiography. CONCLUSION: Half of the patients with common type AFL had a dual-loop macroreentrant circuit consisting of an anterior loop (circuit around the TA) and a posterior loop (circuit around the inferior vena cava and the posterior blocking line).

Adult↗

PubMed2004

Vagal activity modulates spontaneous augmentation of ST elevation in the daily life of patients with Brugada syndrome.

INTRODUCTION: In Brugada syndrome, ventricular fibrillation (VF) occurs mainly during sleep, and Brugada ECG signs are intensified by parasympathomimetic drugs; therefore, vagal activity could be a precipitating factor of VF. The aim of the present study was to elucidate the relation between spontaneous augmentation of ST elevation and changes in autonomic nervous activities in the daily life of patients with Brugada syndrome. METHODS AND RESULTS: Twenty-three consecutive patients with Brugada syndrome were studied. Group VF(+) consisted of 7 symptomatic patients and 3 asymptomatic patients with inducible VF; group VF(-) consisted of 13 asymptomatic patients without documented or inducible VF. Two-channel unipolar lead (V(1) and V(2)) Holter ECG was recorded. Heart rate variability was analyzed by the maximum entropy method. Spontaneous augmentation of ST elevation (>/=1.5 mm/20 min) occurred more frequently during 24 hours in group VF(+) than in group VF(-) (5.7 +/- 2.5 times vs 2.3 +/- 2.4 times, P < 0.01). ST elevation was significantly greater in group VF(+) than in group VF(-) (2.1 +/- 0.2 mm vs 1.8 +/- 0.2 mm, P < 0.05). Power of the high-frequency component (HF: 0.15-0.4 Hz) and RR interval increased progressively, and the ratio of low-frequency component (LF; 0.04- 0.15 Hz) to high-frequency component (LF/HF) gradually decreased toward the time of maximum ST elevation. During an entire day, daytime (0-5 P.M.), and nighttime (0-5 A.M.), both HF and LF/HF were not different between groups VF(+) and VF(-). CONCLUSION: In Brugada syndrome, spontaneous augmentation of ST elevation in daily life occurred along with an increase in vagal activity. ST elevation was augmented more in patients with VF than in those without VF under similar vagal tone.

Adult↗

PubMed2004

Canine model of Brugada syndrome using regional epicardial cooling of the right ventricular outflow tract.

INTRODUCTION: Myocardial cooling can induce J point elevation (Osborn wave) as seen on ECG of the Brugada syndrome by activating transient outward current (Ito) and causing a spike-and-dome configuration of the monophasic action potential (MAP) in the ventricular epicardium in isolated canine ventricular wedge preparations. We determined the effect of regional epicardial cooling of the right ventricular outflow tract (RVOT) on surface ECG and ventricular vulnerability in the dog. METHODS AND RESULTS: In 12 dogs, a cooling device (20-mm diameter) was attached to the RVOT epicardium, and surface ECG, epicardial MAP, and endocardial MAP were recorded. Regional cooling (29.7 degrees C +/- 2.2 degrees C) elevated the J point from 0.05 +/- 0.06 mV to 0.12 +/- 0.11 mV and induced T wave inversion (from 0.02 +/- 0.12 mV to -0.27 +/- 0.20 mV) in lead V1 in association with "spike-and-dome" configuration of the epicardial MAP. Cooling prolonged MAP duration in the RVOT epicardium from 172 +/- 27 ms to 213 +/- 30 ms (P < 0.01) but not in the RV endocardium and increased transmural dispersion of MAP duration from 9 +/- 8 ms to 44 +/- 21 ms (P < 0.01). Cooling also prolonged the QT interval in lead V1 from 191 +/- 19 ms to 212 +/- 23 ms (P < 0.05), but not in lead V5, and increased spatial dispersion of QT interval from 7 +/- 5 ms to 20 +/- 10 ms (P < 0.01). QT interval in lead V1 correlated positively with MAP duration in the RVOT epicardium (r = 0.75). T wave amplitude in lead V1 correlated inversely with transmural dispersion of MAP duration in the RVOT (r =-0.74). Vagal nerve stimulation accentuated the cooling-induced changes. During cooling, ventricular fibrillation was induced by a single extrastimulus in 2 of 4 dogs, and additional vagal nerve stimulation during isoproterenol administration induced spontaneous ventricular fibrillation in one dog. CONCLUSION: Localized epicardial cooling of the RVOT could be an in vivo experimental model of Brugada syndrome.

Action Potentials↗

PubMed2004

Enalapril prevents perpetuation of atrial fibrillation by suppressing atrial fibrosis and over-expression of connexin43 in a canine model of atrial pacing-induced left ventricular dysfunction.

UNLABELLED: Effects of enalapril on a canine model of atrial pacing-induced atrial fibrillation (AF) with rapid ventricular responses were determined. METHODS: Four weeks of atrial rapid pacing was performed on twenty-four beagles pretreated with placebo (Group I, n = 14) or enalapril 1 mg/kg (Group II, n = 10). Atrial effective refractory period (ERP), P-wave width, duration of AF, and left ventricular ejection fraction (LVEF) were evaluated every week. AF cycle length was determined by spectral analyses of fibrillation waves. Quantitative analysis of histology was added. RESULTS: After 4 weeks of pacing, P-wave width was longer in Group I than in Group II, and the duration of induced AF was significantly longer in Group I (59.6 +/- 66.3 seconds) than in Group II (3.6 +/- 3.4 seconds, P < 0.05). AF cycle length was longer in Group I than in Group II despite similar shortening of atrial ERP. Mean ventricular rate during rapid atrial pacing was not different between the two groups. LVEF similarly decreased in both groups. Interstitial fibrosis and expression of connexin43 was greater in Group I than in Group II (interstitial fibrosis, 9.2 +/- 8.4 versus 1.9 +/- 2.1%, P < 0.05; connexin43, 5.3 +/- 2.2 versus 1.1 +/- 1.1%, P < 0.05). CONCLUSIONS: Enalapril suppressed atrial pacing-induced AF with tachycardia-mediated cardiomyopathy by suppressing interstitial fibrosis, connexin43 over-expression and conduction delay.

Animals↗

PubMed2004

Drug-induced changes in fibrillation cycle length and organization index can predict chemical cardioversion of long-lasting atrial fibrillation with bepridil alone or in combination with aprindine.

BACKGROUND: The aim of this study was to investigate whether drug-induced changes in fibrillation wave characteristics can predict pharmacological conversion of long lasting persistent atrial fibrillation (AF). METHODS AND RESULTS: The study group comprised 23 consecutive patients with AF lasting > or =1 month. Patients first received bepridil (200 mg/day) for 2-4 weeks. When sinus rhythm was not restored with bepridil, oral aprindine (40 or 60 mg/day) was added to bepridil. Fast Fourier transform analysis of fibrillation waves using lead V1 was performed to calculate the fibrillation cycle length (FCL). The spectral areas were measured and the maximum area divided by the total area was termed the fibrillation organization index (FOI). Sinus rhythm was restored in 16 of 23 patients (70%); 8 of these 16 patients received only bepridil (Group I) and the other 8 responders received bepridil and aprindine (Group II). In Group I bepridil increased both FCL (p<0.001) and FOI (p<0.01) and terminated AF after 20+/-12 days. In Group II bepridil increased FCL (p<0.001), but did not change FOI. The addition of aprindine terminated AF in association with an increase in both FCL (p<0.005) and FOI (p<0.005) within 19+/-8 days. In the remaining 7 patients who did not have restoration of sinus rhythm, bepridil increased both FCL and FOI significantly, but less than in Group I, and the addition of aprindine did not further increase either of them. Chemical cardioversion of AF occurred in all patients with FCL > or =190 ms and FOI > or =45% after drug administration. CONCLUSION: Bepridil alone or in combination with aprindine converted long lasting persistent AF in association with an increase in both FCL and FOI. The combination of FCL and FOI after drug administration is helpful in predicting chemical cardioversion of persistent AF.

Aged↗

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↗