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Biomedical subjects

Shigeto Naito

Publications and source records attributed to Shigeto Naito.

49 records · Page 3Linked to original sources
PubMed2003

Successful catheter ablation of an anteroseptal accessory pathway from the noncoronary sinus of Valsalva.

We describe a patient who underwent radiofrequency catheter ablation of concealed left lateral and anteroseptal accessory pathways. After successful elimination of the concealed left anterolateral accessory pathway, the earliest retrograde atrial activation was located in the His-bundle region. Complete elimination of the accessory pathway conduction was achieved with a radiofrequency energy application from the noncoronary sinus of Valsalva.

Bundle of His↗
PubMed2003

Development and validation of an ECG algorithm for identifying the optimal ablation site for idiopathic ventricular outflow tract tachycardia.

INTRODUCTION: Idiopathic ventricular outflow tract tachycardia or premature ventricular contractions (OT-VTs) can originate from several different sites in the outflow tract, including the left ventricular (LV) endocardium and epicardium. The aims of this study were (1) to develop an ECG algorithm to predict the origin of OT-VT and (2) to test prospectively the accuracy of the algorithm. METHODS AND RESULTS: An algorithm was developed by correlating the 12-lead ECG findings with the catheter ablation site in 80 patients with OT-VT. The ECG characteristics of the QRS complex during the arrhythmia were analyzed. The catheter sites were verified by multi-plane fluoroscopy. The outflow tract was classified into six subdivisions: right ventricular (RV) septum, RV free wall, RV near the His-bundle region, LV endocardium, left sinus of Valsalva (LSV), and LV epicardium remote from the LSV. An OT-VT originating from the LV epicardium remote from the LSV was defined as an OT-VT in which the earliest ventricular activation was recorded at the LSV and radiofrequency ablation from the LSV failed. This algorithm subsequently was tested prospectively in 88 patients. Overall sensitivity was 88% and specificity was 95%. The positive and negative predictive values were 88% and 96%, respectively. CONCLUSION: We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions.

Adolescent↗
PubMed2003

Failure to raise blood pressure during exercise is a poor prognostic sign in patients with hypertrophic non-obstructive cardiomyopathy.

Sudden cardiac death is a well-documented complication of hypertrophic cardiomyopathy and additionally, failure to raise blood pressure (BP) during exercise has been associated with a poor outcome. The present study group comprised 58 patients with hypertrophic non-obstructive cardiomyopathy (HNCM) who were receiving beta-blocker therapy. All patients underwent submaximal exercise radionuclide ventriculography (RNVG) to evaluate left ventricular (LV) function at both rest and peak exercise. Patients were divided into 2 groups based on the increase in systolic BP during exercise (ie, group A <30% or group N >/=30% of resting systolic BP) and were involved in long-term follow-up (10.4+/-4.0 years). Group A comprised 29% of the subjects. Age and workload at peak exercise were similar in the 2 groups. LV end-diastolic dimension was smaller and the interventricular septum was thicker in group A. LV ejection fraction on RNVG was similar in the 2 groups at rest and at peak exercise. During the follow-up period, more patients in group A than group N suffered syncopal attack (29% vs 5%, p<0.05) and cardiac sudden death (24% vs 2%, p<0.05). Patients with HNCM whose BP fails to rise during exercise have a poor prognosis.

Adrenergic beta-Antagonists↗
PubMed2003

Segmental pulmonary vein isolation for paroxysmal atrial fibrillation improves quality of life and clinical outcomes.

The purpose of this study was to clarify the change in the quality of life (QOL) and clinical outcomes following segmental pulmonary vein (PV) isolation for paroxysmal atrial fibrillation (AF) in 50 patients with drug-refractory, paroxysmal AF. The left superior, left inferior, and right superior PVs were targeted for isolation in all patients, and the right inferior PV was isolated in 4 patients. AF recurred in 22 of 50 patients, and these patients were treated with class I or class III antiarrhythmic drugs that had been ineffective before the ablation procedure. The symptom severity and frequency was scored and the QOL was assessed using the Short-Form-36 questionnaire (SF-36) before the PV isolation and at the end of the follow-up period (6.0+/-3.0 months). PV isolation resulted in a reduction in the symptom severity (p<0.001) and symptom frequency (p<0.001) scores as compared with the pre-ablation values. Ninety percent of the patients had a >90% reduction in the frequency of symptomatic episodes of AF after the ablation procedure. The mean SF-36 physical and mental component summary scores also significantly improved after PV isolation as compared with the pre-ablation values (both for p<0.001). With a segmental isolation approach that targets at least 3 PVs, satisfactory improvement in the symptoms and QOL can be achieved in patients with drug-refractory, paroxysmal AF.

Aged↗
PubMed2003

Impedance cardiography and quantitative tissue Doppler echocardiography for evaluating the effect of cardiac resynchronization therapy: a case report.

An 83-year-old woman presented with dilated cardiomyopathy. Cardiac resynchronization therapy was performed. Two weeks later, cardiac output and ventricular wall motion were estimated using impedance cardiography and tissue Doppler echocardiography with and without pacing. Cardiac output increased from 3.5 to 4.5 l/min during biventricular pacing with a 120 msec atrioventricular interval. Intraventricular phase difference for contraction decreased from 190 to 150 msec. When the atrioventricular interval was 180 msec, cardiac output and phase difference became 4.6 l/min and 170 msec. These assessments were performed rapidly and non-invasively. New impedance cardiography and tissue Doppler echocardiography are useful to evaluate the effect of cardiac resynchronization therapy.

Aged↗
PubMed2003

Efficacy of carvedilol treatment on cardiac function and cardiac sympathetic nerve activity in patients with dilated cardiomyopathy: comparison with metoprolol therapy.

UNLABELLED: Carvedilol and metoprolol have been reported to be effective in the treatment of patients with chronic heart failure. However, to our knowledge, there have been no studies comparing the effects of the 2 drugs on cardiac function, including cardiac sympathetic nerve activity. METHODS: We compared 15 patients with dilated cardiomyopathy (DCM) who were receiving carvedilol (group A) with 15 patients with DCM who were receiving metoprolol (group B). Before and after 1 y of treatment, cardiac (123)I-metaiodobenzylguanidine ((123)I-MIBG) uptake was assessed using the total defect score (TDS) and the heart-to-mediastinum (H/M) activity ratio from the delayed images. The New York Heart Association (NYHA) class and echocardiographic left ventricular ejection fraction (LVEF) also were assessed. RESULTS: In both groups, the TDS decreased (in group A, from 25 +/- 14 to 16 +/- 14, P < 0.01; in group B, from 27 +/- 9 to 19 +/- 10, P < 0.01), the H/M increased (in group A, from 1.67 +/- 0.31 to 2.01 +/- 0.36, P < 0.01; in group B, from 1.68 +/- 0.21 to 1.93 +/- 0.32, P < 0.01), the LVEF increased (in group A, from 31% +/- 10% to 48% +/- 10%, P < 0.01; in group B, from 28% +/- 9% to 47% +/- 15%, P < 0.01), and the NYHA functional class improved (in group A, from 2.9 +/- 0.3 to 1.7 +/- 0.5, P < 0.01; in group B, from 2.8 +/- 0.6 to 1.7 +/- 0.6, P < 0.01). The change in LVEF was mildly correlated with the change in the TDS in group A (r = 0.41) as well as in group B (r = 0.53). In the patients with a favorable response in the TDS or H/M, the NYHA class improved more than in the patients without a favorable response (P < 0.05). CONCLUSION: Carvedilol treatment can improve cardiac function, symptoms, and cardiac sympathetic nerve activity in patients with DCM to a similar extent as metoprolol treatment. The improvement of cardiac function and symptoms is related to the improvement of cardiac sympathetic nerve activity.

3-Iodobenzylguanidine↗
PubMed2002

Nicorandil infusion leads to good recovery from ischemia of left ventricular regional work in comparison with nitroglycerin.

Nicorandil is an antianginal drug that exerts both a conventional nitrate effect and an independent ATP-dependent potassium channel-opening effect. The present study examined the effects of nicorandil on left ventricular regional work (RW) during coronary angioplasty in 22 patients with angina pectoris who were scheduled for angioplasty to the left anterior descending artery. The patients were randomly assigned to receive either nitroglycerin (group NG, n=12, 0.5 microg x kg(-1) min(-1)) or nicorandil (group NR, n = 10, 1.5 microg x kg(-1) min(-1)). Inflation was performed for 60 s and the data were collected every 10 s. The RW was derived from the relation between mean wall stress and area strain. The RW of the interventricular septum decreased after balloon inflation and was at its minimum after the 60s inflation (group NR: 1.24 +/- 0.72mJ/cm3, group NG: 0.63 +/- 0.25mJ/cm3). After balloon deflation, the septal RW of both groups increased, and recovered to the baseline condition at about 30s. At 20 s after deflation, the septal RW in group NR (3.58 +/- 1.17 mJ/cm3) was significantly higher than that in group NG (2.25 +/- 0.59mJ/cm3) (p < 0.05). An intravenous infusion of nicorandil led to good recovery of RW from ischemia compared with that obtained with nitroglycerin.

Aged↗
PubMed2002

Candesartan cilexetil improves left ventricular function, left ventricular hypertrophy, and endothelial function in patients with hypertensive heart disease.

Patients with hypertension often develop left ventricular (LV) hypertrophy and deterioration of the cardiac and endothelial functions. Recent clinical trials have shown the added benefits of angiotensin II receptor blockers in hypertensive patients. Twenty-nine patients with hypertensive heart disease (HHD) underwent echocardiography, radionuclide ventriculography and the measurement of endothelial function before and after administration of candesartan (8 mg/day). The subjects were divided into poorly controlled blood pressure (BP) (group P, n=6) and well controlled BP (group C, n=23). Endothelial function was evaluated from flow-dependent dilation, which was calculated as the percent change of the radial artery diameter during reactive hyperemia after upper arm occlusion, measured with a high-resolution ultrasound system. In group C, LV diastolic function and endothelial function were significantly (p<0.05) improved at 3 months after administration, LV systolic function and hypertrophy were significantly (p<0.05) improved after 6 months and these effects were maintained at 12 months. Even in group P, LV function, LV hypertrophy, endothelial function and brain natriuretic peptide were significantly (p<0.05) improved at 6 months after administration. In patients with HHD, candesartan improves LV systolic and diastolic function, LV hypertrophy and endothelial function within 6 months of administration, regardless of the control of BP.

Adult↗
PubMed2002

[Comparison of clinical and angiographic outcomes between S670 and NIR stents].

OBJECTIVES: This study evaluated the long-term outcomes of successfully implanted S670 and NIR stents. METHODS: Stents were successfully implanted in 143 patients (148 lesions) aged 65 +/- 9 years from January 1999 to April 2001. Sixty-eight lesions were treated with S670 stents and 80 with NIR stents. Quantitative coronary angiography was performed before, immediately after and 6 months after implantation. An angiographic classification of in-stent restenosis was developed according to the geographic distribution of intimal hyperplasia in reference to the implanted stent. Furthermore, the relationships between stent diameter and length and restenosis rate were estimated. RESULTS: Type B2/C lesions were significantly more common in patients with S 670 (77.3%) stents compared with NIR (43.6%). Stent length was longer and diameter was smaller in patients with S 670 stents compared with those with NIR stents. Acute-gain was similar in the two groups, but late-loss was significantly greater in patients with S 670 stents compared with those with NIR stents. Restenosis rate and target lesion revascularization rate were similar in the two groups. The diffuse type of restenosis lesion was frequently found in S 670 stents. The stent diameter, but not stent length, influenced the restenosis rate in S 670 stents. Both stent length and diameter influenced the restenosis rate in NIR stents. CONCLUSIONS: Late-loss was larger and in-stent restenosis of diffuse type was significantly greater in S 670 stents compared with NIR stents. However, stent length was significantly longer and type B2/C lesions were significantly greater in S 670 stents compared with NIR stents. There was no difference in restenosis rate and target lesion revascularization rate. In addition, restenosis rate was not influenced by stent length in S 670 stents, so S 670 stents may be useful for complex lesions.

Aged↗
PubMedDate not supplied

Efficacy of amiodarone treatment on cardiac symptom, function, and sympathetic nerve activity in patients with dilated cardiomyopathy: comparison with beta-blocker therapy.

BACKGROUND: Amiodarone, which is an antiarrhythmic drug used to treat life-threatening arrhythmias, is effective in patients with chronic heart failure. However, its effectiveness compared with beta-blockers has not yet been reported. METHODS AND RESULTS: In 30 patients (mean age, 57 +/- 13 years) with dilated cardiomyopathy, we compared 15 patients receiving amiodarone (group A) with 15 patients receiving metoprolol (group B). Before and after 1 year of treatment, cardiac iodine 123 metaiodobenzylguanidine uptake was assessed from the total defect score, heart-to-mediastinum activity ratio based on delayed images, and washout rate. New York Heart Association class and echocardiographic left ventricular ejection fraction were also assessed. In both groups the total defect score decreased (from 25 +/- 11 to 16 +/- 10 in group A, P <.01; from 26 +/- 10 to 18 +/- 11 in group B, P <.01), the heart-to-mediastinum activity ratio increased (from 1.63 +/- 0.16 to 1.81 +/- 0.29 in group A, P <.01; from 1.63 +/- 0.21 to 1.85 +/- 0.3 in group B, P <.01), and the washout rate decreased (from 51% +/- 12% to 38% +/- 14% in group A, P <.01; from 48% +/- 11% to 37% +/- 8% in group B, P <.01). Left ventricular ejection fraction increased (from 30% +/- 9% to 42% +/- 11% in group A, P <.01; from 26% +/- 7% to 46% +/- 16% in group B, P <.01) and New York Heart Association functional class improved (from 3.1 +/- 0.5 to 1.8 +/- 0.7 in group A, P <.01; from 2.9 +/- 0.5 to 1.7 +/- 0.6 in group B, P <.01). CONCLUSION: Amiodarone treatment can improve cardiac symptom, function, and sympathetic nerve activity, as evaluated by I-123 metaiodobenzylguanidine imaging in patients with dilated cardiomyopathy, which improves to a similar extent with beta-blocker treatment.

Adrenergic beta-Antagonists↗