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Shigeto Naito

Publications and source records attributed to Shigeto Naito.

At least 19 recordsLinked to original sources
PubMed2007

Atrial tachycardia arising from the right atrial inferoseptum masquerading as common atrial flutter.

Radiofrequency catheter ablation was performed in 2 patients with atrial tachycardia (AT). In both cases the AT originated from the inferoseptal portion of the right atrium, and the cycle length was 210 ms. The surface ECG demonstrated common counterclockwise atrial flutter, probably caused by functional block in the clockwise direction at the cavo-tricuspid isthmus and posterior right atrium with rapid activation of the origin. Although rare (2%), AT originating from the inferoseptum of the right atrium should be considered when the surface ECG exhibits common atrial flutter.

Adult↗
PubMed2006

Idiopathic ventricular arrhythmias originating from the tricuspid annulus: Prevalence, electrocardiographic characteristics, and results of radiofrequency catheter ablation.

BACKGROUND: Idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) arising from the tricuspid annulus have been reported. OBJECTIVE: The purpose of this study was to clarify the prevalence and characteristics of VT/PVCs originating from the tricuspid annulus. METHODS: The ECG characteristics and results of radiofrequency (RF) catheter ablation were analyzed in 454 patients with idiopathic VT/PVCs. RESULTS: Thirty-eight (8%) patients had VT/PVCs arising from the tricuspid annulus: 28 VT/PVCs (74%) originated from the septal portion of the tricuspid annulus and the remaining 10 (26%) from the free wall of the tricuspid annulus. QRS duration and Q-wave amplitude in each of leads V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (all P < .01). "Notching" of the QRS complex was observed more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .01). A Q wave in lead V1 was observed more often in VT/PVCs arising from the septum of the tricuspid annulus than those from the free wall of the tricuspid annulus (P < .005). R-wave transition occurred beyond lead V3 more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .005). RF catheter ablation eliminated 90% of the VT/PVCs arising from the free wall of the tricuspid annulus but only 57% of the VT/PVCs arising from septum of the tricuspid annulus. CONCLUSION: Idiopathic VT/PVCs arising from tricuspid annulus are not rare, and the detailed origin can be determined by ECG analysis. The preferential site of origin was the septum but also could be the free wall of the tricuspid annulus.

Cardiac Catheterization↗
PubMed2006

Radiofrequency catheter ablation within the coronary sinus eliminates a macro-reentrant atrial tachycardia: importance of mapping in the coronary sinus.

We describe a patient who underwent radiofrequency (RF) catheter ablation of symptomatic atrial fibrillation. After left atrial (LA) catheter ablation and pulmonary vein isolation, a macro-reentrant atrial tachycardia (AT) with a critical isthmus at the mitral isthmus was induced by incremental atrial pacing from the coronary sinus. Extensive RF energy applications from endocardial sites using ablation catheters with 4 mm- and 8 mm- tips resulted in no discrete potentials being recorded from the endocardial sites of the isthmus, but the tachycardia could not be terminated. However, discrete potentials were recorded within the CS, and epicardial RF energy applications from the CS eliminated the tachycardia. Thus, mapping in the CS is useful for detecting residual conduction at epicardial sites along the mitral isthmus. RF catheter ablation within the CS should be considered when no distinct electrograms are recorded after extensive ablation from the endocardial sites and when distinct electrograms are recorded within the CS.

Atrial Fibrillation↗
PubMed2006

Significance and utility of plasma brain natriuretic peptide concentrations in patients with idiopathic ventricular arrhythmias.

BACKGROUND: Secretion of B-type natriuretic peptide (BNP) appears to be regulated mainly by wall tension, and an increase in the plasma BNP concentration is considered to reflect ventricular structural and functional abnormalities. The aim of this study was to clarify the significance and utility of the measurement of the plasma BNP in the setting of idiopathic ventricular arrhythmias (I-VT/PVCs). METHODS: This study included 135 patients with symptomatic, monomorphic I-VT/PVCs (73 women; 53 +/- 17 years; 50 ventricular tachycardias [VTs], 85 premature ventricular contractions) who underwent radiofrequency catheter ablation. None had structural heart disease or renal dysfunction. RESULTS: The plasma BNP concentration exceeded the normal range (>18.4 pg/mL; high BNP concentration) in 79 patients (56%). The high BNP concentration was found more often in I-VT/PVCs originating from the left ventricle (LV; 74%) than the right ventricle (RV; 49%; P < 0.01). The plasma BNP concentration correlated with the age (P = 0.0001) and frequency of premature ventricular contractions (P < 0.0001), and left-sided I-VT/PVCs and the presence of controlled hypertension were independent predictors of a high BNP concentration (both P < 0.05). In patients with a successful ablation and high BNP concentration before the ablation, the BNP concentration decreased to the normal range in 61% of patients after ablation. In patients with a failed ablation, the BNP concentration did not decrease to the normal range after ablation in any of the patients (P < 0.0005). CONCLUSIONS: The plasma BNP concentration was elevated in about 60% of the patients with symptomatic I-VT/PVCs. Normalization of the high BNP concentration after ablation may indicate a successful ablation.

Adolescent↗
PubMed2006

Usefulness of biventricular pacing to improve cardiac symptoms, exercise capacity and sympathetic nerve activity in patients with moderate to severe chronic heart failure.

BACKGROUND: Although cardiac resynchronization using biventricular pacing (BVP) results in significant clinical improvement in patients with chronic heart failure (CHF), there is no evidence of improvement in sympathetic nerve activity (SNA). METHODS AND RESULTS: Eighteen patients with CHF (dilated cardiomyopathy/ischemic cardiomyopathy =14/4) and left ventricular (LV) ejection fraction <40%, QRS duration >160 ms and dyssynchronous LV wall motion were classified into 2 groups based on the findings of (99m)Tc-methoxyisobutyl isonitrile (MIBI) quantitative gated single-photon emission computed tomography (SPECT) (QGS). Resynchronization was considered to be present when the difference between the QGS frame number for end-systole for the LV septal and lateral walls (dyssynchrony index) disappeared. Group A achieved resynchronization after BVP, but not Group B. In group A, New York Heart Association functional class (p=0.0002), specific activity scale (p=0.0001), total defect score (p<0.05), and the heart/mediastinum ratio of delayed (123)I-metaiodobenzylguanidine imaging (p<0.05) were significantly improved after resynchronization. However, there was no significant change in group B. CONCLUSIONS: Cardiac resynchronization after BVP can improve cardiac symptoms, exercise capacity, and SNA in patients with moderate to severe CHF.

Aged↗
PubMed2005

Idiopathic ventricular arrhythmia arising from the mitral annulus: a distinct subgroup of idiopathic ventricular arrhythmias.

OBJECTIVES: We sought to clarify the prevalence and characteristics of idiopathic ventricular tachycardia or premature ventricular contraction originating from the mitral annulus (MAVT/PVC). BACKGROUND: Recent case reports have presented patients with MAVT/PVC. METHODS: Electrocardiographic (ECG) characteristics and the results of electrophysiologic investigation and radiofrequency catheter ablation (RFCA) were analyzed in 352 patients with symptomatic idiopathic ventricular tachycardia (IVT)/premature ventricular contraction (PVC). RESULTS: Nineteen cases of IVT/PVC (5%) represented MAVT/PVC. Of these, 11 (58%) originated from the anterolateral portion of the mitral annulus (AL-MAVT/PVC), and 2 (11%) arose from the posterior portion (Pos-MAVT/PVC). The remaining six cases of MAVT/PVC (31%) had posteroseptal origin (PS-MAVT/PVC). In all patients, an S-wave was present in lead V(6). The QRS polarity in inferior leads and leads I and aVL was useful for differentiating AL-MAVT/PVC from Pos-MAVT/PVC or PS-MAVT/PVC. The Pos-MAVT/PVC had an Rs pattern in lead I and an R pattern in lead V(1), whereas PS-MAVT/PVC invariably had an R pattern in lead I and a negative QRS component in lead V(1). The AL-MAVT/PVC and Pos-MAVT/PVC showed a longer QRS duration than the PS-MAVT/PVC (p < 0.001), and all had late-phase "notching" of the QRS complex in inferior leads. In all patients, RFCA eliminated MAVT/PVC, with no recurrences during follow-up for 21 +/- 15 months. CONCLUSIONS: Mitral annular VT/PVC is a rare but distinct subgroup of IVT/PVC. MAVT/PVC origin could be determined by ECG analysis. The AL and PS sites of the MA were preferential.

Adult↗
PubMed2005

Tissue tracking imaging as a new modality for identifying the origin of idiopathic ventricular arrhythmias.

Tissue tracking imaging was performed in 33 patients with idiopathic ventricular arrhythmias before radiofrequency catheter ablation. The site of the arrhythmia origin, defined as the site where the earliest color-coded signal appeared on the myocardium at the onset of the arrhythmia, corresponded to the site of origin as determined on fluoroscopy during activation mapping in all patients. Catheter ablation at that site abolished the arrhythmia in 29 patients (88%).

Catheter Ablation↗
PubMed2005

Long-term results of cryoablation with a new cryoprobe to eliminate chronic atrial fibrillation associated with mitral valve disease.

The purpose of this study was to examine the performance of a new cryoprobe in the treatment of chronic atrial fibrillation (AF) associated with mitral valve disease. The study included 66 patients undergoing mitral valve replacement. The mean AF duration was 9.0 +/- 9.0 years and mean left atrial (LA) was diameter 57 +/- 10 mm. Cryoablation (-60 degrees C) was applied to four pulmonary vein (PV) orifices over 2-3 minute. The spherical tip (2-cm in diameter) of the cryoprobe is capable of ablating the left atrium near the PV, as well as the PV ostium with a single cryoablation. After cryoablation, mitral valve surgery or a combined surgical procedure were performed in 66 patients. There were no intraoperative complications. Sinus rhythm was restored in 60 patients (91%) immediately after the operation. Recurrent AF was treated with antiarrhythmic drugs and/or direct current cardioversion in 43 patients (72%). At discharge, 48 patients (72%) were in sinus rhythm. During a mean follow-up period of 31 +/- 16 months, 40 patients (61%) were in sinus rhythm with (29) or without antiarrhythmic drugs (11). In patients in sinus rhythm at the end of the follow-up period, the duration of preoperative AF duration was significantly shorter (P < 0.05) and the preoperative LA diameter and cardiothoracic ratio were significantly smaller than in patients who were in AF (both for P < 0.005). Using this new cryoprobe, sinus rhythm was restored and maintained in 61% of patients with chronic AF and mitral valve disease with a 12-15 minute cryoablation procedure.

Atrial Fibrillation↗
PubMed2005

Biatrial epicardial pacing prevents atrial fibrillation and confers hemodynamic benefits after coronary artery bypass surgery.

Biatrial pacing (BIP) can be more effective than standard right atrial pacing (RAP) in preventing atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG). However, the mechanisms and hemodynamic benefits of BIP have not been studied in detail. This study examined the efficacy and hemodynamic benefits conferred by overdrive epicardial BIP in preventing post-CABG AF. After undergoing CABG, 72 patients (mean age = 66 +/- 12 years, 48 men) were randomly assigned to triggered BIP (BIP-AAT; n = 50) versus single RAP (RAP-AAI; n = 22). The hemodynamic effects of BIP were measured by right heart catheterization and echocardiography. The patients were monitored for 8.8 +/- 2.4 days after CABG to detect episodes of AF. The incidence of AF was significantly lower in the BIP-AAT group (22.0%) than in the RAP-AAI group (59.1%, P < 0.01). Cardiac output was significantly higher and pulmonary artery wedge pressure (PAWP) significantly lower during BIP-AAT than during RAP-AAI. The E-wave (65.2 +/- 37.8 vs 57.8 +/- 37.8 cm/s, P < 0.05) was significantly higher during BIP-AAT, and the interval between atrial pacing spike and the end of A-wave (241 +/- 18.4 vs 286 +/- 17.2 ms, P < 0.001) was significantly shorter during BIP-AAT than during RAP-AAI. Triggered BIP was well tolerated and significantly reduced the incidence of post-CABG AF compared to single-site RAP. The hemodynamic improvements conferred by BIP-AAT were due to a shortening of the inter-atrial conduction delay and greater contribution of left atrial contraction. These hemodynamic benefits may play a role in lowering intra-atrial pressure and in preventing AF.

Aged↗
PubMed2005

Simultaneous mapping in the left sinus of valsalva and coronary venous system predicts successful catheter ablation from the left sinus of valsalva.

Idiopathic ventricular tachycardia originating from the left epicardium (Epi-VT) can be ablated from the left sinus of Valsalva (LSV) in selected patients. We hypothesized that the analysis of electrograms at the LSV and transitional zone from the great cardiac vein to the anterior interventricular vein (GCV-AIV) could predict the efficacy of radiofrequency catheter ablation (RFCA) from the LSV. Simultaneous mapping in the LSV and coronary venous system was performed in 25 patients (12 VTs and 13 premature ventricular contractions). The earliest ventricular activation (VA) during the arrhythmias was found at the LSV or GCV-AIV in all patients. RF applications from the LSV were successful in 17 patients success group (S-Gr) and failed in 8 failure group (F-Gr). The earliness of the VA recorded in the LSV (VA[LSV]) and in GCV-AIV (VA[GCV-AIV]) was compared between the two groups. (1) The VA[LSV] preceded the QRS onset by 28 +/- 11 ms in S-Gr and 14 +/- 10 ms in F-Gr (P < 0.01). (2) In S-Gr, the VA[GCV-AIV] was earlier than the VA[LSV] in 5 five patients (35%). However, in F-Gr, the VA[GCV-AIV] was earlier than the VA[LSV] in all patients. (3) In patients in whom the earliest VA was found at the LSV or GCV-AIV, a VA [GCV-AIV] preceding the VA[LSV] by less than 10 ms identified successful RFCA from the LSV with a sensitivity of 88 %, specificity of 100%, and high predictive value. With a detailed analysis of the electrograms recorded from the GCV-AIV and LSV, it was possible to identify the successful catheter ablation of Epi-VT from the LSV.

Catheter Ablation↗
PubMed2005

Pulmonary vein morphology before and after segmental isolation in patients with atrial fibrillation.

BACKGROUND: The morphology of the pulmonary veins (PVs) before and after segmental isolation of the PVs has not been sufficiently characterized. METHODS AND RESULTS: Multi-slice computed tomography was performed before and 3 +/- 1 months after ablation in 30 patients with atrial fibrillation who underwent PV isolation. Before ablation, PV narrowing (> or =25% luminal reduction) was found in nine (8%) PVs. After ablation, de novo PV narrowing was found in 24 PVs (26%) and was detected only in the supero-inferior direction in 14 PVs (58%). The diameter reduction inside the PVs after ablation was greater in the supero-inferior direction (14 +/- 12%) than in the antero-posterior direction (9 +/- 13%; P < 0.0001). In the ablated PVs, the PV trunk was shorter than before ablation (P < 0.0001). The reduction in the diameters of both the PV ostium and the ablation site in the ablated PVs, as well as the diameter of the PV ostium in the nonablated PVs, correlated with the decrease in the left atrial diameter. Shortening of the PV trunk correlated with the severity of PV narrowing, but it was not related to the percent diameter reduction of the left atrium. PV narrowing before or after ablation did not result in any clinical consequences. CONCLUSIONS: PV narrowing is present in about 10% of PVs before ablation. Asymmetric luminal reduction and longitudinal shrinkage of the PV trunk occur after ablation. Reverse remodeling of the PV and contraction of the PV wall may contribute to the reduction in the PV diameter. PV morphology should be assessed with multi-directional views to avoid missing heterogeneous legions.

Analysis of Variance↗
PubMed2005

Left atrial and pulmonary vein ostial ablation as a new treatment for curing persistent atrial fibrillation.

BACKGROUND: Segmental pulmonary vein (PV) isolation has been performed to eliminate paroxysmal atrial fibrillation (AF). However, this technique is not effective in most patients with persistent AF. METHODS AND RESULTS: Left atrial catheter ablation (LACA) was performed by encircling the left- and right-sided PV 1-2 cm from the ostia, guided by an electroanatomical mapping system in 16 patients with persistent AF (>1 month). Twelve patients (75%) had a history of unsuccessful transthoracic cardioversion and prophylactic antiarrhythmic drugs. Ablation lines were also created in the mitral isthmus and posterior LA. PV isolation was also performed for each PV if there were residual PV potentials after the LACA. After LACA, 38 PV (59%) were completely isolated, and complete PV isolation was achieved with only a few radiofrequency energy applications (2.7+/-2.0 min) on a narrow area of the PV ostium (24+/-15%) in the remaining PV. The mean procedure time was 200+/-38 min. During the follow-up period (17+/-3 months), 12 patients (75%) had normal sinus rhythm and were free of symptomatic AF with (n = 10) or without antiarrhythmic drugs (n = 2). One patient had a stroke just after the procedure. No other complications including PV narrowing (>50%) occurred. CONCLUSION: This approach was effective in persistent AF, however, concomitant use of antiarrhythmic drugs was often required.

Aged↗
PubMed2005

Percutaneous transvenous mitral commissurotomy and radiofrequency catheter ablation in patients with mitral stenosis.

BACKGROUND: The purpose of this study was to evaluate the short- and long-term results of radiofrequency catheter ablation (RFCA) for the treatment of atrial fibrillation (AF) in patients with mitral stenosis (MS) following percutaneous transvenous mitral commissurotomy (PTMC). METHODS AND RESULTS: Four patients (2 males, age 59+/-6 years) underwent simultaneous PTMC and pulmonary vein (PV) ablation. All patient had AF and MS (2 had persistent AF >1 month, 2 had paroxysmal AF), and the mean duration of AF was 3.4+/-3.3 years. The mean left atrial dimension was 47+/-7 mm and the mean ejection fraction was 58+/-4%. After PTMC, RFCA was performed in all patients (3 underwent PV isolation and 1 had PV focal ablation). The mitral valve area increased from 1.11 +/-0.19 to 1.90+/-0.20 cm(2) (p < 0.01). The frequency of AF episodes was dramatically reduced in the 2 patients with paroxysmal AF, and the 1 with persistent AF maintained sinus rhythm, but 1 patient with persistent AF developed recurrent AF. No complications or cardiac events occurred in any of the patients. CONCLUSION: The combination of RFCA and PTMC was safe and feasible, and may be useful in patients with MS and AF.

Catheter Ablation↗
PubMed2005

Three-dimensional visualization of the coronary venous system using multidetector row computed tomography.

BACKGROUND: This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of the coronary venous system (CVS) by multidetector row computed tomography (MDCT). METHODS AND RESULTS: A total of 70 patients underwent MDCT and for each patient, 6 data sets were created throughout the cardiac cycle. The number and location of coronary veins were evaluated in 3-dimensional images using the 6 data sets. The quality of all images reconstructed from the 6 data sets was too poor to evaluate the CVS in 6 patients (9%). In the remaining 64 patients (91%), the diameter of the CVS was usually greater in the images reconstructed from data acquired during systole than in those reconstructed from data acquired during diastole. However, artifacts were observed more often in images from systole than from diastole. The coronary sinus and middle cardiac vein were visible in all 64 patients. The left marginal and posterior veins also were identified in 54 (84%) and 60 patients (94%), respectively. CONCLUSIONS: MDCT can be used as a non-invasive modality for evaluating the CVS anatomy in most patients.

Adult↗
PubMed2005

Tissue Doppler imaging and strain Doppler imaging as modalities for predicting clinical improvement in patients receiving biventricular pacing.

BACKGROUND: The purpose of this study was to determine the utility and efficacy of tissue Doppler imaging (TDI) and strain Doppler imaging (SDI) for evaluating ventricular synchrony and function, and for predicting the long-term clinical improvement in patients undergoing biventricular pacing (BVP). METHODS AND RESULTS: TDI and SDI were performed before and <1 month after initiating BVP in 17 patients with advanced heart failure. An intraventricular conduction delay between the left ventricular (LV) septal and lateral walls was measured by TDI. The average LV strain (LV-strain) was calculated from data obtained at the center of 6 regions of the LV (base and mid-point between the basal and apical portions, and the mid-point between these 2 points on the septal and lateral walls). During a 23+/-7 month follow-up period, 12 patients improved clinically and did not require re-hospitalization for heart failure (responder group), but the remaining 5 did not improve (nonresponder group). Before BVP, the intraventricular conduction delay was greater in the responder group than in the nonresponder group (p<0.01), but after BVP, it did not differ between the 2 groups. LV-strain improved after BVP in the responder group but not in the nonresponder group (p<0.05). CONCLUSION: A high intraventricular conduction delay before BVP and decreased strain shortly after BVP may predict long-term clinical improvement in patients undergoing this treatment.

Aged↗
PubMed2005

Left atrial appendage outflow velocity is superior to conventional criteria for predicting of maintenance of sinus rhythm after simple cryoablation of pulmonary vein orifices.

BACKGROUND: We sought to identify factors favoring long-term restoration of sinus rhythm (SR) in patients with atrial fibrillation (AF) who underwent a simple cryoablation of pulmonary vein orifices (PV-cryo) as part of their cardiac surgery. METHODS AND RESULTS: Of 101 patients with AF undergoing PV-cryo, the 71 in SR at discharge were grouped according to whether they maintained or lost SR (group SR, n = 61, and group AF, n = 10) after an average of 2.3 years. Atrial fibrillation present at discharge (n = 30) persisted during follow up. Comparisons were made to identify preoperative predictive factors, including transthoracic and transesophageal echocardiographic parameters. Of patients discharged from the hospital with SR, 92% (46 of 50) of those with AF duration of 3 years or less were in group SR, as were 92% (23 of 25) of those with left atrial dimension of 50 mm or less, and 93% (37 of 40) of those with average peak left atrial appendage outflow velocities (LAA-V) of at least 30 cm/s. Of 25 patients in group SR who had no paroxysmal AF and did not require antiarrhythmic drugs, all had LAA-V over 20 cm/s. Patients in group AF all had LAA-V under 40 cm/s. CONCLUSIONS: Left atrial appendage outflow velocities was the best predictor of whether SR was maintained long-term after PV-cryo.

Aged↗