Biomedical subjects

Shigeto Naito

Publications and source records attributed to Shigeto Naito.

At least 37 records · Page 2Linked to original sources

PubMed2005

Catheter ablation of tachycardias after undergoing a surgical atriotomy using a multipolar electrode catheter: conventional mapping method without an electroanatomical mapping system.

BACKGROUND: A variety of supraventricular tachyarrhythmias may occur in patients after undergoing a surgical atriotomy. The purpose of this study was to characterize them and determine the role of conventional mapping. METHODS AND RESULTS: In 45 patients after a surgical atriotomy, 68 atrial tachyarrhythmias were observed. A conventional mapping system with a 20-pole electrode catheter used in the electrophysiological study detected 39 atrial tachycardias (ATs). Type 1 atrial flutter (AFL) was observed in 23 and reverse type 1 AFL in 4. AT was classified into 3 subgroups, namely, incisional macroreentrant AT (n=31), incisional focal AT (n=1) and non-incisional AT (n=7). In the patients with incisional macroreentrant AT after the standard right atriotomy, the 20-pole electrode catheter placed on the incision could easily record the entire sequence of the atrial activation. Successful catheter ablation was achieved in all patients with incisional reentrant AT. The ablation site of incisional reentrant AT was the isthmus between the incision and the superior vena cava cannulation scar in 4, between the incision and the inferior vena cava cannulation scar in 22, and the area at the septal incision in 3. The remaining 2 incisional ATs were left atrial AT and right atrial transincisional AT. CONCLUSIONS: The conventional mapping system is still very useful for making an electrophysiological diagnosis in patients after a standard right atriotomy.

Adult↗

PubMed2005

Idiopathic premature ventricular contractions arising from the pulmonary artery: importance of mapping in the pulmonary artery in left bundle branch block-shaped ventricular arrhythmias.

A patient underwent radiofrequency (RF) catheter ablation of symptomatic idiopathic ventricular contractions (PVCs). RF energy applications at 2 sites in the right ventricular outflow tract (RVOT), where both the earliest ventricular activation and near-perfect pace mapping were obtained, did not abolish the PVC but resulted in changes in the QRS morphology of the PVC. Complete elimination of the PVC was achieved with RF energy application at a site within the pulmonary artery 13 mm above the pulmonary valve, which was greater than 20 mm away from the failed ablation sites within the RVOT.

Adult↗

PubMed2005

Acute myocardial infarction and ischemia in the left anterior descending artery territory in a patient with single coronary artery.

This report describes a 77-year-old woman with a single coronary artery who suffered an acute anterior wall myocardial infarction. The single coronary artery arose from the right coronary artery through the transverse trunk, and there were no other cardiovascular anomalies. Coronary angiography did not reveal significant coronary artery stenosis in the left anterior descending artery. The patient was treated medically in the acute phase. She developed typical angina and evidence of myocardial ischemia, and underwent successful coronary artery bypass grafting in the chronic phase with anterior chest pain.

Aged↗

PubMed2005

Effectiveness of distal protection with the GuardWire Plus during primary angioplasty for acute myocardial infarction.

OBJECTIVES: To evaluate the effectiveness of distal protection with the GuardWire Plus during primary angioplasty in patients with acute myocardial infarction. METHODS: Thirty-eight consecutive patients undergoing stent implantation with distal protection using the GuardWire Plus (DP-group) were compared with a matched control group undergoing conventional stent implantation after balloon angioplasty without distal protection (NDP-group). Microvascular circulation after revascularization was assessed by Thrombolysis in Myocardial Infarction (TIMI) flow grade, myocardial blush grade (MBG), serum creatine kinase peak release, and ST resolution. Left ventricular ejection fraction was measured by echocardiography at discharge. Follow-up quantitative coronary angiography and left ventriculography were performed 6 months after percutaneous coronary intervention. Quantitative coronary angiography data, restenosis rate, target lesion revascularization rate and follow-up left ventricular ejection fraction were also compared between the two groups. RESULTS: No significant differences were observed in baseline clinical and angiographic characteristics between the two groups. The TIMI flow grade 3 (DP-group 81.6% vs NDP-group 57.9%)and MBG 3 (57.9% vs 30.6%)were significantly greater in the DP-group respectively (p < 0.05). Post procedural ST-segment resolution > or = 50% was found in a significantly higher percentage of patients in the DP-group (68.4% vs 42.1%, p < 0.05). Left ventricular ejection fraction at discharge was significantly greater in the DP-group (55.5 +/- 8.5% vs 45.7 +/- 11.1%, p < 0.05). However, 6 months after the percutaneous coronary intervention, no significant difference was observed between the two groups. Restenosis rate and target lesion revascularization rate were similar in the two groups. CONCLUSIONS: Distal protection with the GuardWire Plus improved the microvascular circulation as assessed by TIMI flow grade, MBG, and ST resolution. Furthermore, left ventricular ejection fraction at discharge was improved.

Aged↗

PubMed2004

Usefulness of quantitative gated single-photon emission computed tomography to evaluate ventricular synchrony in patients receiving biventricular pacing.

Quantitative gated single-photon emission computed tomography was performed in 10 patients before and shortly after (<1 month) receiving biventricular pacing (BVP). They were divided into 2 groups (responder and nonresponder groups) on the basis of clinical status and echocardiographic parameters 18 +/- 6 months later. In the responder group, left ventricular synchrony shortly after BVP improved significantly compared with that before BVP (p <0.05), but there was no change in the nonresponder group.

Aged↗

PubMed2004

Persistent tachycardia with a 2:1 exit block within an isolated pulmonary vein.

We describe a patient with drug-resistant, paroxysmal atrial fibrillation who underwent segmental pulmonary vein (PV) isolation. After complete isolation of the right superior PV, a persistent regular tachycardia was recorded within the vein. A tachycardia focus with a cycle length of 114 ms was found 2.5 cm away from the ostium of the PV. The cycle lengths of the PV tachycardia near the ostium and near the focus were 400 ms and 200 ms, respectively, which indicates the presence of a 2:1 exit block within the vein. This PV tachycardia was completely eliminated with the application of radiofrequency energy at the focus.

Atrial Fibrillation↗

PubMed2004

Persistent tachycardia originating from the superior vena cava as a driver for atrial fibrillation.

We describe a patient with drug-resistant paroxysmal atrial fibrillation who underwent radiofrequency catheter ablation of tachycardia originating from the superior vena cava (SVC). A continuous and rapid tachycardia conducted to the atrium with evidence of exit block and drove atrial fibrillation (AF) and atrial tachycardia. Neither AF nor atrial tachycardia could be induced after SVC isolation, and nor were they observed during follow-up. We conclude that continuous and rapid tachycardia originating from the SVC can act as a driver as well as an initiator of AF.

Atrial Fibrillation↗

PubMed2004

Unidirectional atrio-atrial conduction after surgical isolation of the posterior part of the left atrium and pulmonary veins for atrial fibrillation: simple postsurgical procedure electrophysiological evaluation.

A 66-year-old woman underwent mitral valve replacement and surgical isolation of the posterior part of the left atrium for persistent AF. During sinus rhythm an isolated atrial rhythm was recorded from the isolated posterior left atrium using an esophageal electrode catheter. After the intravenous administration of adenosine triphosphate sinus rhythm was suppressed and 1:1 conduction from the posterior left atrium to the rest of the atrium was recorded. Unidirectional atrio-atrial conduction was revealed by a simple electrophysiological evaluation

Adenosine Triphosphate↗

PubMed2004

Significance of two potentials for predicting successful catheter ablation from the left sinus of Valsalva for left ventricular epicardial tachycardia.

The aim of this study was to identify the characteristics of electrograms that may be helpful in predicting successful ablation of idiopathic ventricular tachycardia from the aortic sinus of Valsalva. Data were obtained from 23 patients with symptomatic ventricular tachycardia or premature ventricular contractions (LV-VT) who underwent RF catheter ablation from the left sinus of Valsalva. Electrograms before and after application of RF energy during sinus rhythm and during LV-VT were analyzed. Complete elimination of LV-VT was finally achieved in 21 (91%) patients. The incidence of presystolic potentials preceding the QRS complex of LV-VT (P1 potential) was 90% for the 21 successful ablation sites, which did not differ from the incidence for the 24 unsuccessful sites (79%; P = 0.5). During sinus rhythm, a potential following the QRS complex (P2 potential) was more often recorded at the successful ablation site than at an unsuccessful ablation site before and after application of RF energy (before, P < 0.05; after, P < 0.001). The appearance of the P2 potential or a delay in the preexisting P2 potential after application of RF energy was observed only at the successful ablation sites (P < 0.001). In 18 control individuals who had no LV-VT, no P2 potential was recorded within the left sinus of Valsalva. Although the P1 potential may be useful for identifying the successful ablation site, its sensitivity is low. The appearance of the P2 potential or an increasingly delayed P2 potential after application of RF energy may be more useful than the P1 potential for predicting successful ablation.

Catheter Ablation↗

PubMed2004

Prevalence and characteristics of idiopathic outflow tract tachycardia with QRS alteration following catheter ablation requiring additional radiofrequency ablation at a different point in the outflow tract.

Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.

Adult↗

PubMed2004

Successful catheter ablation of atrial tachycardia originating near the atrioventricular node from the noncoronary sinus of Valsalva.

This report describes a patient who underwent RF catheter ablation of atrial tachycardia. Two applications of RF energy near the His-bundle region transiently terminated the tachycardia. With detailed mapping at the aortic sinus of Valsalva using a retrograde transaortic approach, the earliest atrial activation was found in the noncoronary sinus of Valsalva. Complete elimination of the tachycardia was achieved with RF energy application from this site.

Atrioventricular Node↗

PubMed2004

Evaluation of salvaged myocardium after acute myocardial infarction using single photon emission computed tomography after 201Tl-glucose-insulin infusion.

BACKGROUND: GIK-201Tl imaging reportedly improves the detection of viable myocardium, so the present study evaluated whether it can detect myocardial viability after acute myocardial infarction (AMI). METHODS AND RESULTS: Resting 201Tl and 99mTc-pyrophosphate (PYP) dual single photon emission computed tomography (SPECT) and 201Tl SPECT after 201Tl with GIK (10% glucose, insulin 5 U, and KCl 10 mmol) infusion (GIK-201Tl) were performed in 25 AMI patients within 10 days of admission. GIK-201Tl SPECT images were obtained immediately and 4 h after infusion. Left ventriculography (LVG) was performed within 3 weeks and at 6 months when follow-up 201Tl SPECT was also performed. From 20 SPECT segments, both the summed defect score (RDS) and the number of defect segments (ES) were calculated. The infarcted area was defined as 99mTc-PYP uptake segments. Wall motion was estimated in 7 LVG segments. The ES of R-201Tl (5.5 +/- 2.8), immediate GIK-201Tl (4.0 +/- 2.3), and 4-h GIK-201Tl (5.6 +/- 2.7) were lower than that of 99mTc-PYP (7.5 +/- 4.1) (p<0.05), and the ES had significantly declined 6 months later on 201Tl (3.5 +/- 2.8) (p<0.05). Although the RDS of R-201Tl (11.3 +/- 7.9) and 4-h GIK-201Tl (11.2 +/- 6.3) were greater than at the 6-month 201Tl (7.1 +/- 6.5), immediate GIK-201Tl (7.4 +/- 6.5) was equivalent to follow-up 201Tl. The sensitivity of immediate GIK-201Tl was highest among the imaging methods. CONCLUSION: To detect myocardial viability after AMI, early imaging with GIK-201Tl is more useful than resting 201Tl imaging.

Aged↗

PubMed2004

Prevalence and electrocardiographic characteristics of idiopathic ventricular arrhythmia originating in the free wall of the right ventricular outflow tract.

BACKGROUND: The prevalence and ECG characteristics of idiopathic ventricular arrhythmia originating in the free wall of the right ventricular outflow tract (RVOT) require further clarification, which was the aim of the present study of 110 patients with idiopathic ventricular tachycardia (n=34) or premature ventricular contraction (n=76; OT-VT/PVC) who underwent successful catheter ablation at the RVOT. METHODS AND RESULTS: Ten OT-VT/PVCs (9%) were ablated successfully at the free wall (FW-VT/PVC); the remaining 100 (91%) were ablated at the RVOT septum (Sep-VT/PVC). R wave amplitudes in the inferior leads were significantly smaller in FW-VT/PVC than in Sep-VT/PVC (p<0.01). An RR' pattern in the inferior leads was observed significantly more often in FW-VT/PVC than in Sep-VT/PVC (p<0.001). QS-wave amplitude in each of leads V(1) to V(3) was significantly deeper in FW-VT/PVC than in Sep-VT/PVC (p<0.001). ECG criteria requiring an RR' pattern in all inferior leads as well as an S-wave amplitude of at least 3.0 mV in lead V(2) differentiated FW-VT/PVC from Sep-VT/PVC with high sensitivity, specificity, and predictive accuracy. CONCLUSIONS: Although FW-VT/PVC has a relatively low prevalence, it has several distinctive ECG characteristics and detailed ECG analysis can differentiate it from Sep-VT/PVC.

Adult↗

PubMed2004

Factors predicting success in cryoablation of the pulmonary veins in patients with chronic atrial fibrillation.

BACKGROUND: This study was designed to investigate the factors predicting maintenance of sinus rhythm (SR) in patients with chronic atrial fibrillation (AF) undergoing cryoablation of the pulmonary veins (PV-cryo) during cardiac surgery. METHODS AND RESULTS: Seventy-seven patients with AF undergoing PV-cryo were recruited and divided into 2 groups based on whether they were able to maintain SR at discharge. The duration of AF (AF-D), left atrial dimension (LAd), and the average of the peak left atrial appendage outflow velocities (LAA-V) before surgery were determined for both groups. Group SR consisted of 54 patients (70%), and group AF consisted of 23 patients (30%). All patients with an AF-D 40 cm/s were in group SR and all those with an AF-D >10 years and LAd >or=65 mm were in group AF. Only 71% of patients with a LAA-V <or=20 cm/s were in group AF. CONCLUSIONS: Restoration of AF to SR by PV-cryo can be predicted from a knowledge of the AF-D, LAd and LAA-V.

Aged↗

PubMed2004

[Does cardiac resynchronization therapy improve nitric oxide concentration in exhaled gas?].

OBJECTIVES: Cardiac resynchronization therapy (CRT) is widely known to improve cardiac function in patients with chronic heart failure, especially those with increased intraventricular conduction delay. However, whether vascular endothelial cell function is improved remains unknown. Capability of nitric oxide (NO) production is a good marker to evaluate endothelial cell function. Therefore, NO output was measured in exhaled air in patients with chronic heart failure after CRT. METHODS: Six patients with chronic heart failure and dilated cardiomyopathy (mean age 62.0 +/- 11.3 years, left ventricular ejection fraction 22.8 +/- 11.6%) received CRT. Pacing leads were lodged at the right atrium, the apex of the right ventricle and at the mid portion of the postero-lateral branch of the coronary sinus. One month after CRT, endtidal NO concentration was evaluated with and without pacing using the chemiluminescence method. RESULTS: Left ventricular ejection fraction improved from 22.8% to 28.8% after the procedure. Endtidal NO was significantly (p = 0.038) increased from 64.7-13.2 ppb without pacing to 69.1-14.1 ppb with pacing. Respiratory rate (with pacing: 19.7-5.7 n/min, without pacing: 20.3-4.8 n/min), tidal volume (with pacing: 523.2-122.7 ml, without pacing: 516.2-160.3 ml) and minute ventilation were not changed. CONCLUSIONS: CRT did not affect respiratory rate, tidal volume or minute ventilation, so increased endtidal NO did not result from enhanced production from tracheal and/or bronchial epithelial cells. Therefore, endtidal NO increased because chronic heart failure increased pulmonary perfusion and so raised vascular shear stress. CRT for patients with dilated cardiomyopathy can improve vascular endothelial cell function.

Aged↗

PubMed2003

Delayed recovery of left ventricular regional work after coronary angioplasty in patients with opposite wall old myocardial infarction.

To evaluate the changes in left ventricular (LV) regional function during acute ischemia in patients with opposite wall old myocardial infarction (OMI), we examined LV regional work during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending artery (LAD) in patients with a posterior OMI. Twelve patients with normal LV contraction (group A) and six patients with posterior OMI (group B) who were scheduled to undergo PTCA were enrolled in this study. All patients had single-vessel coronary artery disease and no collateral circulation. Sixty-second inflation was performed, and data were collected every 10 s. The regional work was calculated from the relationship between the mean wall stress and area strain. Regional work of the interventricular septum decreased after balloon inflation and was at its minimum at the end of inflation (group A: 0.6 +/- 0.3 mJ/cm(3); group B: 0.8 +/- 0.4 mJ/cm(3)). After balloon deflation, the septal regional work increased in both groups, and recovered to baseline at 40 s in group A and at 60 s in group B. Regional work of the posterior wall increased in group A after balloon inflation, but not in group B. The recovery of LV regional work after PTCA is delayed in patients with opposite-wall OMI.

Adult↗

PubMed2003

Sulfonated human immunoglobulin enhances CD16-linked CD11b expression on human neutrophils.

Intravenous human immunoglobulin therapy infrequently results in excessive inflammatory responses in vivo; these effects are not fully understood. We assessed whether sulfonated human immunoglobulin (SHIG) or polyethylene glycol-treated human immunoglobulin (PHIG) enhanced expression of inflammatory receptors on peripheral blood neutrophils in vitro, such as alphaMbeta2 (CD11b/CD18) and Fc gamma receptor type III (FcgammaRIII). CD11b and CD16 expression on neutrophils was measured by fluorescence flow cytometry. Various cytokines were assessed using a highly sensitive fluorescence microsphere system. SHIG enhanced/induced CD11b expression and partial aggregations on neutrophils, but PHIG did not. No detection of aggregation IgG was observed in SHIG and PHIG. SHIG-induced CD11b expression was inhibited by treatment of corticosteroid (dexamethasone) and by anti-CD16 monoclonal antibody. Concentrations of various cytokines such as interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, RANTES, tumor necrosis factor (TNF)-alpha, and interferon (INF)-gamma in culture supernatant were not significantly changed by SHIG or PHIG. SHIG and PHIG did not enhance CD16 on neutrophils. SHIG enhanced CD16-linked CD11b expression on neutrophils in vitro. CD11b induction was inhibited by dexamethasone and by anti-CD16 antibody. These in vitro results suggest that aggregations and enhancement of CD11b on neutrophils by SHIG may induce excessive inflammatory responses in vivo.

Antibodies↗

PubMed2003

Concealed left anterior accessory pathways: two approaches for successful ablation.

Left anterior accessory pathways are considered to occur rarely because the junction between the aortic and mitral valve areas represents a fibrous continuity. Of 207 patients with concealed left accessory pathways in whom catheter ablation was performed at our institution over the past 8 years, two patients had concealed left anterior accessory pathways. The polarity of the retrograde P waves was positive in the inferior leads and negative in leads I and aVL during orthodromic reciprocating tachycardia. Complete elimination of accessory pathway conduction was achieved using a transseptal approach or with radiofrequency energy application from the left sinus of Valsalva.

Adolescent↗