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Toshihiko Nanke

Publications and source records attributed to Toshihiko Nanke.

9 recordsLinked to original sources
PubMed2004

New holter monitoring analysis system: a calculation of the lead vectors.

BACKGROUND: A new system of synthesizing a 12-lead electrocardiogram (Syn-ECG) with practically identical waveforms to the standard 12-lead ECG (Stn-ECG) from 3-channel ECGs recorded by Holter monitoring has been developed. METHODS AND RESULTS: The study group comprised 16 healthy individuals and 13 patients with abnormal ECGs. The bipolar eV1, eV5 and eVF leads were recorded using digital Holter monitoring and nine Syn-ECGs, corresponding to each lead of the Stn-ECG, were synthesized. The 9 ECGs consisted of a theoretical Syn-ECG and 8 Syn-ECGs positioned around the theoretical Syn-ECG at 3 cm intervals on the Frank's image surface. Of the 9 ECGs, the Syn-ECG with the maximum product of the cross-correlation coefficient of the QRS wave and that of the T wave, was automatically selected as the optimal Syn-ECG. The amplitude data from the QRS wave, R wave, T wave, and ST level, and also the amplitude ratio of the R wave, T wave to the QRS wave, were significantly well correlated between the Syn-ECG and Stn-ECG. CONCLUSIONS: A practically identical ECG morphology, comparable with a Stn-ECG, was successfully created using this system.

Adult↗
PubMed2003

Influence of mobile magnetic resonance imaging on implanted pacemakers.

PURPOSE: Mobile magnetic resonance imaging (MRI) systems will be widely used in Japan. When traveling, mobile MRI generate alternating electromagnetic waves which may cause electromagnetic interference (EMI). This study was designed to determine whether this may influence the function of implanted pacemakers (PM). METHODS AND RESULTS: The influence of the static magnetic fields was tested in the first method using a PM-human model (Phantom). Magnetic force was simultaneously measured. The PM was switched to the magnet mode within 90 cm from the vehicle, where the magnetic force was = 2 mT. In the second method, six phantoms were placed on the side of the road, facing in three different directions in X-Y-Z axis orientations, at 1.3 m and 2.0 m above the ground. The mobile MRI passed by at a distance of 1 m from the phantoms at the speed of 20 or 40 km/h. In these experiments, magnet mode switch of the PM was observed for 2 seconds when the vehicle passed close to the phantoms, though no electrical noise was recorded. CONCLUSION: Mobile MRI vehicles can switch a PM to magnet mode when the distance between patient and vehicle is < 90 cm, regardless of whether the vehicle is moving or at a stop. Patients with implanted PM should not approach within < 1 m of a mobile MRI. No other EMI-induced PM dysfunction was detected.

Electromagnetic Fields↗
PubMed2003

Experimental study on the effectiveness and safety of radiofrequency catheter ablation with the cooled ablation system.

Experimental in vitro and in vivo studies were performed to assess the effectiveness and safety of the cooled-tip catheter and the Cooled Ablation System, which enables the creation of deeper and wider burn lesions in the myocardial tissue using radiofrequency current. This system was confirmed to consistently create large burns by cooling the catheter tip with circulating water within the catheter, even under unfavorable conditions. On the other hand, unfavorable effects, as a result of over burning, such as explosive vaporization within the tissue (the 'pop' phenomenon), tissue carbonization, coronary artery injury and lung injury were identified. 'Pop' was difficult to predict, but it is important to know how it can be avoided. No 'Pop' was seen without first observing an impedance decrease, thus it was considered safe to decrease the radiofrequency current if the impedance began to decrease. This system will be very effective for ablation of refractory arrhythmias, such as ventricular tachycardia or atrial flutter, but it is recommended that only experienced electrophysiologists use this system to avoid serious complications.

Animals↗
PubMed2003

Autonomic imbalance as a property of symptomatic Brugada syndrome.

The autonomic properties in 27 patients with the electrocardiographic morphology of Brugada syndrome were investigated using 24-h Holter monitoring: 10 patients had a history of ventricular fibrillation (VF; Br-VF group) and 17 did not (Br-N group); there were 26 healthy subjects enrolled in this study. All subjects underwent normal Holter data monitoring and power spectral analysis. Few extrasystoles were observed in either group, and the mean heart rate (HR), maximum HR, and total heart beats over 24 h were obtained. All of these measurements were significantly lower in the Br-VF group than in the Br-N and healthy subject groups. The RR interval variability was analyzed over 512 beats every 10 min. The high-frequency component (0.15-0.40 Hz; HF), low-frequency component (0.04-0.15 Hz; LF) and the LF/HF ratio were analyzed over 24 h. The HF was significantly higher and LF/HF ratio lower in the Br-VF group than in the healthy subjects. The HF was also significantly higher than in the Br-N group. During the night (00.00-05.00 h), the HF was significantly higher in the Br-VF group, and the LH/HF lower. During the day (12.00-17.00 h), the HF was significantly higher in the Br-VF group, but there was no difference in the LF/HF. These results indicate that high vagal tone and low sympathetic tone are specific properties of symptomatic Brugada syndrome.

Autonomic Nervous System Diseases↗
PubMed2003

Reversible ischemic neurological deficit (RIND) due to exercise testing for the diagnosis of angina pectoris.

A 57 year old Japanese male with chest oppression due to exercise is presented. This symptom was likely due to effort angina pectoris. Master's double two-step test revealed ischemic ST segment depression on the electrocardiogram, thus, a Tl201 myocardial stress imaging test using a bicycle ergometer was undertaken. Immediately following the exercise test, the patient experienced dizziness and palsy in his left upper and lower limbs. Cerebral angiography demonstrated 70% stenosis at the right internal carotid artery, but no abnormal findings were demonstrated on a cranial x-ray CT scan and magnetic resonance imaging. His palsy in the left limbs completely recovered within 3 weeks. Thus this event was diagnosed as a reversible ischemic neurological deficit (RIND). Major but non-cardiogenic complications during exercise testing are very rare, and RIND has not been reported thus far to the best of our knowledge.

Angina Pectoris↗
PubMed2002

Prolongation of LAS40 (duration of the low amplitude electric potential component (<40 microV) of the terminal portion of the QRS) induced by isoproterenol in 11 patients with Brugada syndrome.

The electrophysiological mechanism of Brugada syndrome is unclear, but transmural dispersion of repolarization in the right ventricle is believed to be the most likely mechanism. On the other hand, the presence of a conduction delay region is considered to be related to the occurrence of ventricular fibrillation; that is, a relationship between the presence of a ventricular late potential (LP) and arrhythmogenic right ventricular cardiomyopathy. In this study, the LP from signal-averaged electrocardiography during isoproterenol (ISP) administration in patients with Brugada syndrome is discussed. The subjects were 11 patients with Brugada syndrome and 6 healthy individuals. In all subjects, the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS(40)), duration of the low amplitude electric potential component (40 microV) of the terminal portion of the QRS (LAS(40)), and time duration of the fQRS-LAS(40) difference were compared between when ISP was prescribed and when it was not. During ISP administration, a peculiar response, which resulted in an LAS(40) prolongation, was observed in the patients with Brugada syndrome. With ISP, the fQRS remained unchanged, but the RMS(40) and the fQRS-LAS(40) decreased. Consequently another 3 patients with a positive LP were diagnosed using the ordinary standard because of the administration of ISP. We believe that the low-amplitude component was unmasked by shortening of the high-amplitude component. In patients with Brugada syndrome, a conduction delay in the ventricle may be present and may be related to the occurrence of ventricular fibrillation.

Adult↗
PubMed2002

Clinical significance of the dispersion of the activation--recovery interval and recovery time as markers for ventricular fibrillation susceptibility in patients with Brugada syndrome.

Brugada syndrome (BS) is associated with sudden cardiac death and the markers for ventricular fibrillation (VF) remain unclear, so the activation-recovery interval (ARI) dispersion and recovery time (RT) dispersion were investigated as possible markers in 20 subjects with BS (BS group) and 22 healthy individuals (H group). The 20 BS subjects were divided into 8 cases with documented VF (BS-VF group), 3 of which had recurrences, and 12 without (BS-N group). The corrected dispersion measurements from the standard 12-lead ECG of the QT interval (QTcd), ARI (ARIcd) and RT (RTcd) were compared among the groups. There were significant differences noted between the BS-VF and BS-N groups for the ARIcd and the RTcd, but not for the QTcd. Further, there were critical differences, 150 ms(1/2), observed for the ARIcd and RTcd, and these were associated with a prolongation of the maximum ARI or RT, shortening of the minimum ARI or RT, and prolongation only of the maximum QT for the QTcd. Susceptibility to VF may be predicted by the ARIcd or RTcd in BS.

Arrhythmias, Cardiac↗
PubMed2002

Electrocardiography subtraction method of detecting low-amplitude, high-frequency components (L-HFCs) within the QRS complex of patients with ventricular tachycardia.

A new method of extracting the low-amplitude and high-frequency components (L-HFCs) was developed and this study investigated its usefulness in 86 subjects: 28 normal subjects (group 1) and 58 patients with a previous myocardial infarction (MI). The patients were classified into 3 groups: group 2 with 38 patients without ventricular tachycardia (VT), group 3 with 13 patients with non-sustained VT, and group 4 with 7 patients with sustained VT. The new electrocardiography (ECG) subtraction method, using a mathematical filtering procedure, was used instead of conventional complex filtering. The continuous L-HFCs within the QRS complex were analyzed using a Z-lead recording. The duration of the continuous L-HFCs was significantly longer in group 4 than in groups 1 (p<0.0001), 2 (p<0.0001) or 3 (p<0.05) with all 3 filters. The ECG subtraction method is a powerful and useful new technique for identifying patients at risk for either sustained or non-sustained VT after MI, and overcomes several of the problems with the conventional signal-averaging method.

Adult↗