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Biomedical subjects

Teiichi Yamane

Publications and source records attributed to Teiichi Yamane.

At least 19 recordsLinked to original sources
PubMed2006

Dual mechanisms underlying pulmonary vein tachycardias in a patient with paroxysmal atrial fibrillation.

We report a case of a 46-year-old man with paroxysmal atrial fibrillation who underwent pulmonary vein isolation. After a complete isolation of each pulmonary vein was performed, two different types of pulmonary vein tachycardia appeared: a regular tachycardia in the left inferior pulmonary vein with a supposed reentrant mechanism, and an irregular tachycardia in the right superior PV showing a nonreentrant character.

Atrial Fibrillation↗
PubMed2006

Elevated plasma brain natriuretic peptide level in cardiac sarcoidosis patients with preserved ejection fraction.

We sought to examine whether the plasma brain natriuretic peptide (BNP) levels are elevated in the cardiac sarcoidosis patients even with a preserved ejection fraction. The data from the patients with either pulmonary sarcoidosis without any evidence of cardiac involvement (n = 13) or cardiac sarcoidosis (n = 8) with a preserved ejection fraction (>55%) on echocardiography were analyzed. The median plasma BNP levels were significantly higher in the patients with cardiac sarcoidosis than in those with pulmonary sarcoidosis (101.5 +/- 65.1 vs. 15.6 +/- 10.5 pg/ml, p < 0.001), although there was no significant difference in left ventricular ejection fraction between the two populations. The plasma BNP level is thus considered to be a useful non-invasive biomarker for identifying a possible cardiac involvement in the sarcoidosis patients with a preserved ejection fraction.

Adult↗
PubMed2006

Behavior of atrial ectopic beats before and after pulmonary vein isolation in patients with atrial fibrillation: a reduction in the number and arrhythmogenicity of ectopic firings.

BACKGROUND: No studies evaluating in a quantitative manner the effect of pulmonary vein (PV) isolation on the behavior of atrial premature beats have been reported. OBJECTIVES: The purpose of this study was to reveal the behavior of atrial premature beats before and after PV isolation in patients with paroxysmal atrial fibrillation (AF). METHODS: In 108 patients free from AF following PV isolation, both the number of atrial premature beats and their coupling intervals before and following PV isolation were evaluated with periodic 24-hour ambulatory monitoring. RESULTS: After a successful PV isolation procedure (group 1, n = 78), the number of atrial premature beats significantly decreased with two distinct time courses: an acute reduction on the following day and a subsequent gradual decrease throughout the whole observation period. The mean atrial premature beat coupling interval at baseline was 420 +/- 30 ms, which was significantly prolonged to 560 +/- 100 ms at 3 months after PV isolation (P <.01). Although patients with AF recurrence after PV isolation (group 2, n = 30) had transiently depressed atrial premature beats shortly after the procedure, they recovered to the former level 3 months after PV isolation. Repeat PV isolation targeting the reconnected PVs successfully suppressed these residual atrial premature beats both in their number and the coupling interval in a manner similar to those in group 1. CONCLUSION: Successful PV isolation reduced the number of atrial premature beats with both rapid and gradual time courses. The residual atrial premature beats appeared less arrhythmogenic, with longer coupling intervals than those at baseline. AF recurrences after PV isolation were associated with increased atrial premature beat number and shortened coupling interval, which were depressed by reisolation of reconnected PVs.

Atrial Fibrillation↗
PubMed2006

Pseudosinus tachycardias originating from left pulmonary veins.

The case of a 55-year-old man with LV dysfunction in whom the baseline cardiac rhythm falsely mimicked a sinus rhythm (SR) but actually originated from the left superior and inferior pulmonary vein (PV) is reported. The P waves before ablation were flat in leads I and V1, negative in lead aVL, and positive in leads II, III, aVF. After the left superior PV was isolated from the left atrium, another ectopic rhythm newly appeared from the left inferior PV. Interestingly, the LV systolic function improved after the resumption of the SR, thus suggesting that tachycardia-induced cardiomyopathy might be involved in the mechanism of LV systolic disturbance.

Atrial Premature Complexes↗
PubMed2005

Nicorandil inhibits serum starvation-induced apoptosis in vascular endothelial cells.

The Impact Of Nicorandil in Angina (IONA) randomized trial showed a significant reduction in coronary events, in patients with stable angina treated with a KATP channel opener, nicorandil. However, the impact of nicorandil on endothelial apoptosis remains to be examined. We tested the hypothesis that nicorandil has anti-apoptotic effects in endothelial cells (ECs). Apoptosis was induced by serum starvation in the culture media in human umbilical vein endothelial cells. We examined the effects of nicorandil on endothelial cell apoptosis. Cell viability after serum starvation was significantly higher in the nicorandil-treated group compared with the control group (81 +/- 8% vs. 63 +/- 3%, P < 0.01). Apoptosis, as detected by caspase 3 activation and Hoechst 33258 assay, induced by serum starvation was also effectively abrogated by the treatment of nicorandil (100 muM). The protective effects of nicorandil on endothelial survival were significantly inhibited by a specific mitochondrial KATP channel blocker, 5-Hydroxydecanoic acid. A mitochondrial permeability transition pore activator significantly abolished the anti-apoptotic effect of nicorandil in endothelial cells, indicating that the mechanism of protective effect of nicorandil is involved in the mitochondrial apoptotic pathway although it affects neither Bcl-2 nor Bax protein expression levels. In conclusion, nicorandil inhibits serum starvation-induced endothelial cell apoptosis possibly through mitochondrial KATP channels.

Angina Pectoris↗
PubMed2005

Focal source of atrial fibrillation arising from the ostium of the inferior vena cava.

A patient presented with paroxysmal atrial fibrillation (AF) caused by focal rapid discharges arising from the ostium of the inferior vena cava (IVC). Surface ECG showed typical features of AF and flutter when rapid activation at the IVC ostium was conducted to the right atrium in a 1-to-1 and 2-to-1 fashion, respectively. Discrete radiofrequency energy applications at the medial ostium of the IVC completely eliminated the atrial tachyarrhythmias.

Atrial Fibrillation↗
PubMed2005

Atrial septal pacing to resynchronize atrial contraction and improve atrial transport function.

OBJECTIVES: Atrial septal pacing via a trans-septal breakthrough site within the right atrial septum can shorten global atrial activation time, resulting in significant reduction of recurrence of atrial fibrillation events. This study examined whether this pacing method will lead to resynchronization of atrial contraction and its benefit on hemodynamic function can be maintained for 24 months. METHODS: Thirty patients with atrial fibrillation and delayed atrial conduction were enrolled (17 males, 13 females, mean age 73 +/- 7 years). Trans-septal breakthrough site within the right atrial septum was identified through pacing from the dorsal left atrium. Continuous atrial septal pacing at the trans-septal breakthrough site was performed for 24 months. Time difference (TD) between right and left atrial contractions was measured during atrial septal pacing and sinus rhythm by pulse Doppler echocardiography of the trans-tricuspid (P-At) and mitral (P-Am) blood flows (TD = P-Am - P-At). RESULTS: The atrial lead was screwed near the fossa ovalis in 29 of 30 patients. Atrial septal pacing yielded significantly shorter P wave duration (101.9 +/- 10.4 vs 139.6 +/- 14.7 msec, p < 0.001), leading to significant reduction of TD in atrial contraction (-8.8 +/- 10.0 vs 29.8 +/- 13.6 msec, p < 0.001)as compared to sinus rhythm. Both shorter P wave duration and reduced TD during atrial septal pacing remained statistically significant during the follow-up period as compared to sinus rhythm. Both left atrial diameter and A to E ratio of filling waves at mitral valve were significantly decreased at 12 months and remained decreased at 24 months. CONCLUSIONS: Atrial septal pacing at the trans-septal breakthrough site can resynchronize atrial contraction and results in improved hemodynamic effects during 24 months of follow-up.

Aged↗
PubMed2004

A focal source of atrial fibrillation in the superior vena cava: isolation and elimination by radiofrequency ablation with the guide of basket catheter mapping.

Although it has been reported that pulmonary veins sometimes act as a focal driver of atrial fibrillation (AF), little has been reported concerning the contribution of the superior vena cava (SVC) to the maintenance of AF. Here we report a patient with sustained AF due to focal discharges inside the SVC after pulmonary vein isolation procedure. Stepwise radiofrequency current applications with the guide of multielectrode basket catheter mapping first disconnected the arrhythmogenic SVC from the right atrium and then eliminated the tachycardia.

Atrial Fibrillation↗
PubMed2003

Various routes of septal propagation in common atrial flutter.

INTRODUCTION: Although in the treatment of common atrial flutter, the isthmus between the tricuspid valve annulus and the eustachian ridge is often chosen as the site for conduction block by radiofrequency ablation, the precise path of the flutter circuit remains unknown. We therefore investigated the propagation of the atrial flutter wave front around the coronary sinus ostium and how its path is altered by application of radiofrequency current. METHODS AND RESULTS: To assess activation pattern, activation in the region surrounding the coronary sinus ostium was mapped using a deflectable decapolar catheter under basal conditions and while applying radiofrequency current to the septal isthmus, between the tricuspid valve annulus and the eustachian ridge. In five of eleven patients studied, the eustachian ridge side, below the coronary sinus ostium, was activated earlier, and the flutter wave exited from either the tricuspid valve annulus side or the eustachian ridge side, above the coronary sinus ostium. In four patients, a partial line of block created by applying radiofrequency current between the tricuspid valve annulus and the coronary sinus ostium or between the coronary sinus ostium and the eustachian ridge led to a shift in the direction of propagation of the flutter wave front from anterior to posterior or from posterior to anterior of the coronary sinus ostium, and prolongation of the cycle length. CONCLUSION: Application of radiofrequency current to the septal isthmus, between the tricuspid valve annulus and the eustachian ridge, can shift both the anterior and posterior propagation of flutter around the coronary sinus ostium.

Aged↗
PubMed2003

Coronary artery spasm discovered in thorough examination of perioperative VT in a 26-year-old Japanese male.

We thoroughly examined a 26-year-old Japanese male who experienced perioperative ventricular tachycardia. After inhaling sevoflurane, his nasal cavity was soaked with 1:100,000 epinephrine and he was intubated through the nose. Junctional tachycardia occurred five minutes after intubation, changing to ventricular tachycardia. Six-time cardioversion was required to stop the ventricular tachycardia. Echocardiography immediately following the event showed diffuse hypokinesis, and an electrocardiogram showed an inversion of T waves in II, III, aVF and V4-6. Both returned to normal within a few days. Tl scintigraphy revealed a normal perfusion image. Coronary angiography showed a normal coronary, but an injection of acetylcholine induced vasospasm in the right coronary artery. Examination of left ventricular tissue yielded no specific findings. During electrophysiological tests, ventricular tachycardia could not be induced even in the presence of isoprenaline. This is a very young case to elicit vasospasm in the coronary artery with no underlying heart disease. Although the relationship between perioperative ventricular tachycardia and coronary spasm is unknown, cardiac events can occur during anesthesia in young and low-risk patients.

Acetylcholine↗
PubMed2002

Left atrial appendage activity masquerading as pulmonary vein potentials.

BACKGROUND: Despite extensive proximal ablation, all potentials frequently cannot be eliminated from the left pulmonary veins (PV). Methods and Results- PV electrograms were analyzed during sinus rhythm, coronary sinus, and left atrial appendage (LAA) pacing, and PV and LAA angiography performed. During pacing, an initial low-amplitude slow potential was recorded on the anterior aspect of the left superior PV and anticipated with shortest activation time by LAA pacing. Its timing coincided with posterior LAA activation, shown to be immediately adjacent to the left superior PV by angiography. In the left inferior PV, the first potential was smaller and less sharp, coinciding with adjacent low LA activation. Angiographically, the LAA was at least 15 mm from the left inferior PV. The second sharper potential in both left PVs was eliminated by proximal ablation. CONCLUSION: Far field LAA activity consistently adds to PV myocardial electrograms in the left superior PV whereas lower, less sharp extravenous potentials in the left inferior PV originate from the inferior LA. They can be identified by LAA and coronary sinus pacing.

Action Potentials↗
PubMed2002

Electrogram polarity reversal as an additional indicator of breakthroughs from the left atrium to the pulmonary veins.

OBJECTIVES: We assessed the anatomical distribution and electrogram characteristics of breakthrough from the left atrium (LA) to the pulmonary veins (PVs). BACKGROUND: Localization of LA-PV breakthrough is an important technique for PV ablation in patients with atrial fibrillation (AF). METHODS: A total of 157 patients with paroxysmal AF underwent PV disconnection guided by mapping with a circumferential 10-electrode catheter. Radiofrequency (RF) current was delivered ostially at the site(s) of earliest activation (113 patients) or electrogram polarity reversal defined by opposite polarity across adjacent bipoles (44 patients). Breakthrough sites were proved by changes in pulmonary vein potential activation sequence occurring as a result of localized RF delivery and were classified into four segments around the ostium (top, bottom, anterior, posterior). Results of mapping and ablation were compared between the two groups. RESULTS: A total of 99% of 411 targeted PVs were successfully disconnected in both groups. Breakthroughs were most frequent at the bottom of superior PVs (85% prevalence) and the top of inferior PVs (75% prevalence). A wide activation front (>5 synchronous bipoles) indicating broad breakthrough was observed in 18% of PVs. Polarity reversal occurred with 88% sensitivity and 91% specificity at breakthrough sites. Polarity reversal was restricted to fewer bipoles (2.0 +/- 0.4 bipoles vs. 3.4 +/- 2.0 bipoles, p < 0.01) compared with earliest activation. Shorter RF application time was required to disconnect PVs with wide synchronous activation using polarity reversal compared with using conventional earliest activity (10.3 +/- 3.0 min vs. 12.3 +/- 3.4 min, p < 0.05). CONCLUSIONS: Bipolar electrogram polarity reversal allows more precise localization of breakthrough compared with the earliest activation, particularly in cases of wide synchronous PV activation.

Adult↗
PubMed2002

Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.

Ventricular fibrillation is the main mechanism of sudden cardiac death, but the source of its spontaneous initiation has not been mapped. 16 patients were investigated by electrography and radiofrequency ablation after resuscitation from recurrent idiopathic ventricular fibrillation. Triggers of ventricular fibrillation originated from various locations within the Purkinje system in 12 patients and from the ordinary myocardial muscle in four. The accuracy of mapping was confirmed by acute elimination of triggers by radiofrequency delivery, and there was no recurrence of ventricular fibrillation in 14 patients. Long-term follow-up is necessary to establish that ablation is curative and avoids use of a defibrillator.

Adolescent↗
PubMed2002

Effect of low-dose isoproterenol infusion on left atrial appendage function soon after cardioversion of chronic atrial tachyarrhythmias.

BACKGROUND: Cardioversion of chronic atrial fibrillation or atrial flutter to sinus rhythm is often associated with transient atrial mechanical dysfunction, i.e. 'atrial stunning', which may increase the risk of subsequent thromboembolic events. We hypothesized that, because of its positive inotropic action, a low-dose isoproterenol infusion might improve postcardioversion atrial mechanical function. METHOD: Eighteen patients (15 male, three female; 12 atrial fibrillation, six atrial flutter; mean age 65+/-10 years) exhibiting atrial postcardioversion stunning were included in the study. Isoproterenol was infused for 10 min at a dose sufficient to increase the heart rate by about 10%. Using transesophageal echocardiography, both the left atrial appendage emptying/filling flow velocity and function (fractional area change) were examined at baseline, before isoproterenol (immediately after cardioversion) and after isoproterenol. RESULTS: With infusion of 0.005-0.008 microg/kg/min isoproterenol, heart rate increased by 11.1+/-2.9%, and left atrial appendage emptying velocity, which was diminished following cardioversion, increased significantly (P<0.001) (baseline, before and after isoproterenol: 41.1+/-18.0, 20.3+/-8.5 and 27.3+/-9.6 cm/s, respectively). No major complications were associated with isoproterenol infusion. CONCLUSIONS: Short-term infusion of low-dose isoproterenol improved atrial function after cardioversion of chronic atrial fibrillation and atrial flutter.

Aged↗