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Biomedical subjects

S Kamakura

Publications and source records attributed to S Kamakura.

At least 91 records · Page 5Linked to original sources
PubMed1995

Long-term outcome of verapamil-sensitive sustained left ventricular tachycardia in patients without structural heart disease.

OBJECTIVES: This study attempted to determine the long-term outcome of verapamil-sensitive sustained left ventricular tachycardia in patients without apparent structural heart disease. BACKGROUND: Several types of idiopathic ventricular tachycardia have been reported, and their clinical, electrophysiologic and electropharmacologic characteristics are different. It is possible that the prognosis of each type of ventricular tachycardia might also be different. METHODS: We studied mortality and morbidity in 37 consecutive patients (27 male, 10 female; mean [+/- SD] age 33 +/- 14 years) with verapamil-sensitive sustained left ventricular tachycardia who had no apparent structural heart disease. Patients were followed up for 1 to 13 years (mean 5.8). Verapamil repeatedly terminated ventricular tachycardia in all patients. Ventricular tachycardia originated from the inferior and inferoseptal regions of the left ventricle in 33 patients and the superior and superioseptal regions in 4. Severity of ventricular tachycardia was classified according to the extent to which symptoms limited daily activities. Ventricular tachycardia was mild (minimal limitation) in 14 patients, moderate (some limitation) in 17 and severe (severe limitation) in 6. RESULTS: Fourteen patients with mild ventricular tachycardia were followed up without any drug therapy, and the ventricular tachycardia remained mild in all patients. Antiarrhythmic therapy was initiated empirically in the 23 patients with moderate and severe ventricular tachycardia (verapamil in 20, propranolol in 2, digoxin in 1). Moderate ventricular tachycardia became mild ventricular tachycardia after drug therapy in all patients, but the six patients with severe ventricular tachycardia showed no improvement. The six patients with severe ventricular tachycardia had nonpharmacologic therapy (cryosurgery in one, catheter ablation in four, antitachycardia pacing device in one). During the follow-up period, all patients remained alive except for one who died suddenly after implantation of an antitachycardia pacing device. CONCLUSIONS: 1) The long-term prognosis of verapamil-sensitive sustained left ventricular tachycardia in patients without apparent structural heart disease is good. 2) Verapamil is the drug of choice for alleviating symptoms, but nonpharmacologic therapy is necessary in some patients.

Adolescent↗
PubMed1995

Intraoral reconstruction with innervated forearm flap: a comparison of sensibility and reinnervation in innervated versus noninnervated forearm flap.

OBJECTIVE: To evaluate the cutaneous sensibility and sensory reinnervation in patients who underwent intraoral reconstruction with an innervated or noninnervated forearm flap. STUDY DESIGN: Results of the use of innervated forearm flaps in oral reconstruction was compared with the use of noninnervated flaps. The evaluation of sensibility and reinnervation comprised clinical sensibility tests and immunohistochemical investigation of postoperative biopsy specimens against S-100 and neurofilament. RESULTS: The innervated flaps (4 patients) provided earlier and qualitatively better recovery of sensation than the noninnervated flaps (9 patients). Immunohistochemical investigation revealed the existence of a larger number of regularly arranged sensory nerve fibers in the cutaneous tissue of the innervated flaps than in the noninnervated flaps. Examination with an electron microscope found the structure of these nerve fibers to be well preserved in the innervated flaps, whereas nerve fibers in the noninnervated flaps were degenerative. CONCLUSION: These findings suggest (1) that the innervated flaps are superior to the noninnervated flaps not only for the repair of defects but also for the restoration of function and (2) that the innervated flaps contribute to the improvement of the quality of life for patients.

Adult↗
PubMed1995

Dynamic relationship between the Q-aT interval and heart rate in patients with long QT syndrome during 24-hour Holter ECG monitoring.

The purpose of this study was to investigate the dynamic relationship between heart rate and the Q-aT interval (the interval from the Q wave to the T wave apex) in patients with long QT syndrome. The QT to heart rate relation is useful for evaluating abnormalities of the ventricular repolarization, but its clinical application to the long QT syndrome requires accurate computer aided measurement of the QT interval and the sampling of a large number of beats. Therefore, the Q-aT interval was used on the basis of some reports that the heart rate dependency of the QT interval was concentrated in the Q-aT interval. Recent advances in the computer technology have allowed analysis of the relationship between the Q-aT and RR intervals on Holter ECG recordings. However, in addition to a prolonged QT interval, most patients with long QT syndrome have bizarre and variable T waves and the influence of this T wave morphology on the Q-aT to heart rate relation has not been clarified. We investigated the dynamic relationship between the Q-aT interval and heart rate in 10 patients with long QT syndrome and 11 control subjects using our original computer algorithm for the analysis of 24-hour Holter ECG recordings. The patients showed morphological T wave changes associated with heart rate changes during Holter recordings and these affected the Q-aT interval. The patients showed the following characteristics in the relationship between the major T wave peak and the RR interval: (1) a modestly decreased correlation between Q-aT and RR than in the control subjects (a median r value of 0.87 vs 0.93; P = 0.001); and (2) a steeper Q-aT/RR slope than in controls (a median slope of 0.24 vs 0.16; P < 0.05). Abnormal and variable T wave morphology in the long QT patients was closely related to a modestly decreased correlation between Q-aT and RR than in the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

[Relationship between prognosis and electrocardiographic characteristics in patients with left bundle branch block].

The purpose of this study is to investigate the electrocardiographic characteristics that determine the prognosis in patients with CLBBB. This study included 42 patients with CLBBB who could be followed up more than 5 years. 18 patients had no structural heart disease (group A), and 24 patients had structural heart disease (group B). 12 leads ECG and body surface mapping were recorded in all patients. Cardiac event was observed in 17 patients, and 16 of them were in group B, VAT in middle back was statistically longer in cardiac event group than non cardiac event group. In group B, VAT in middle back was also statistically longer in cardiac event group. Prolongation of VAT in middle back, prolongation of QRS duration, abnormality of QRS isopotential map, and abnormality of QRST isointegral map were useful indices for predicting cardiac event in patients with CLBBB.

Aged↗
PubMed1995

[Localization of the origin of idiopathic right ventricular tachycardia by body surface mapping].

To find the electrocardiographic indices for localizing the origin of idiopathic right ventricular tachycardia (VT), we investigated body surface maps and standard electrograms of 26 VTs of right ventricular outflow origin that were successfully abolished by radiofrequency catheter ablation. The origins were classified into three dimensional relationships; anterior (free wall) and posterior (septal), left (anterior attachment = AA) and right (posterolateral attachment = PA), and upper (near pulmonary valve = NP) and lower (far from pulmonary valve = FP) regions. The following indices on early to mid QRS isopotential maps were useful for localization; the location of minimum for differentiating free wall from septal origin, the potential distribution of upper left anterior chest for differentiating AA from PA region, and the time interval for which the minimum stays at upper anterior chest for differentiating NP from FP region. Electrocardiographic morphology in leads I, II and III, the amplitude of QS wave in leads aVR and aVL, and the amplitude of initial r wave in leads V1 and V2 were also reliable indices for localizing the origin of VT.

Adult↗
PubMed1995

[Body surface mapping in patients with hypertrophic cardiomyopathy (HCM)].

The purpose of this study is to investigate the electrocardiographic indices that estimate the site of myocardial hypertrophy and the presence of ventricular tachyarrhythmia in patients with HCM. This study included 43 patients, 11 of them had episodes of ventricular tachyarrhythmia (9; sustained ventricular tachycardia, 2; ventricular fibrillation). Three patterns of QRS isopotential map were observed, each was characterized with apical, septal, and dilated phase HCM. VAT in left lateral chest to left back was statistically longer in patients with ventricular tachyarrhythmia. QRS isopotential map was useful for estimating the site of myocardial hypertrophy, and VAT ischrone map was useful for predicting ventricular tachyarrhythmia in patients with HCM.

Body Surface Potential Mapping↗
PubMed1995

[Comparison of body surface maps with epicardial maps in patients with Wolff-Parkinson-White syndrome].

To investigate the ventricular activation process reflected on body surface maps, we compared body surface isopotential and isochrone maps with epicardial isochrone maps in 39 patients with Wolff-Parkinson-White syndrome. The epicardial earliest activation site, the latest activation site and the distribution of isochrone line during mid QRS period were reflected well on the location of minimum during early QRS period, the location of maximum during terminal QRS period, and the movement of base line during mid QRS period on isopotential maps respectively. Right ventricular breakthrough via normal conduction pathway was recognized on epicardial maps in most patients with left sided or septal accessory pathway, though some patients had it on isopotential maps and a few patients had it on isochrone maps. The unique distribution of initial minimum in patients with posteroseptal pathway was caused by the ventricular fusion of the preexcitation at diaphragmatic base and the normal activation at right ventricular free wall.

Adult↗
PubMed1994

Diagnostic value of recovery time measured by body surface mapping in patients with congenital long QT syndrome.

The QT interval of the resting 12-lead electrocardiogram is normal or borderline in some patients with congenital long QT syndrome (LQTS). Recently, several in vivo experimental studies have shown that the time of maximum dV/dt in the ST-T segment is correlated with the time of local ventricular recovery. The purpose of this study was to examine the value of the body surface recovery time measured by 87-lead body surface mapping for detecting LQTS. Body surface mapping and 12-lead electrocardiography were performed simultaneously in 18 patients with LQTS and 40 controls of similar age and sex. The recovery time (RT), that is, the interval between QRS onset and the time of maximum dV/dt in the ST-T segment, was measured automatically by computer from each of the 87 mapping leads, and the corrected RT (RTc) was calculated by Bazett's method. The QT interval was measured from each of the 12 standard electrocardiographic leads, and the corrected QT (QTc) interval was also calculated. The maximum RT and RTc, the minimum RT and RTc, and the RT and RTc dispersions (difference between maximum and minimum RT and RTc in each patient) were significantly longer in the LQTS group than in the control group. In addition, a maximum RT of 390 msec, a maximum RTc of 430 msec 1/2, an RT dispersion of 170 msec, and an RTc dispersion of 170 msec1/2 separated the 2 groups completely (i.e., no overlap). The maximum QT and QTc, the minimum QT and QTc, and the QT and QTc dispersions (difference between maximum and minimum QT and QTc in each patient) were also significantly longer in the LQTS group than in the control group. However, the maximum QTc was normal (< or = 440 msec1/2) or borderline (< or = 460 msec1/2) in 5 of the 18 LQTS patients, and none of these parameters clearly separated the 2 groups. These results suggest that measurement of RT by 87-lead body surface mapping is useful for diagnosing latent or borderline LQTS.

Adolescent↗
PubMed1993

Effects of hemodialysis on body surface maps in patients with chronic renal failure.

To examine the effects of hemodialysis on the electrocardiogram, 87-lead body surface maps were performed in 38 patients with chronic renal failure, before and after hemodialysis. The patients were divided into two groups; 16 patients with coronary artery disease (CAD group), and 22 patients without ischemic heart disease (control group). Three maps were analyzed, QRS isopotential maps, isochrone maps, and QRS isointegral maps. Parameters measured were maximal R wave voltage (Peak R), minimal QRS wave voltage (Peak S), maximal ventricular activation time (VATmax) and QRS duration (QRSd). In the control group, Peak R and Peak S increased but VATmax decreased after hemodialysis. There were negative correlations between the changes of body weight and the changes in Peak R (r = -0.67, p < 0.01) and Peak S (r = -0.87, p < 0.001), although there were no correlations between changes in left ventricular diastolic dimension and the changes in Peak R and Peak S. In the CAD group, Peak S increased but Peak R and VATmax did not change significantly. There were negative correlations between the change of body weight and the change of Peak S (r = -0.73, p < 0.01). The most pronounced changes in mean QRS isointegral maps on hemodialysis were an increased magnitude of positivity in the control group and negativity in the CAD group on the anterior thorax. These findings suggested that the increase in the QRS amplitude after hemodialysis was influenced by the changes of the conductivity of extracardiac thorax and the relative heart position to the chest wall rather than myocardial ischemia or ventricular conduction delay.

Adult↗
PubMed1992

Frequency analysis of signal-averaged electrocardiogram in patients with right ventricular tachycardia.

OBJECTIVES: The purpose of this study was to analyze the frequency content of signal-averaged electrocardiograms (ECGs) in patients with idiopathic ventricular tachycardia of right ventricular origin and in patients with arrhythmogenic right ventricular dysplasia. BACKGROUND: The late potentials in the time domains are usually found in patients with arrhythmogenic right ventricular dysplasia. They are not usually found in patients with idiopathic ventricular tachycardia of right ventricular origin. METHODS: Fast Fourier transform analysis of signal-averaged ECGs was performed with the use of a Blackman-Harris window in 43 subjects: 20 normal volunteers (group I), 12 patients with idiopathic ventricular tachycardia of right ventricular origin (group II) and 11 patients with arrhythmogenic right ventricular dysplasia (group III), and the frequency spectrum was displayed in a three-dimensional graph. Area ratio (ratio of the area under the spectral plot from 40 to 120 Hz to the area from 0 to 120 Hz) was calculated in all subjects. RESULTS: Area ratio was significantly higher in group II than in group I (243 +/- 45 vs. 196 +/- 15, p < 0.01) and significantly higher in group III (396 +/- 51) than in group I or II (p < 0.001). The high frequency components in group II were confined within the QRS complex in the three-dimensional graph, whereas those in group III extended outside the QRS complex. CONCLUSIONS: Frequency analysis of the signal-averaged ECG with fast Fourier transform analysis can detect the high frequency components in patients with right ventricular tachycardia, including idiopathic ventricular tachycardia and arrhythmogenic right ventricular dysplasia.

Adult↗
PubMed1992

Bradycardia-induced abnormal QT prolongation in patients with complete atrioventricular block with torsades de pointes.

Fourteen patients with complete atrioventricular block with or without torsades de pointes (TdP) were included in this study. They were divided into 2 groups, 6 patients with TdP (TdP[+] group) and 8 patients without TdP (TdP[-] group). The patients were evaluated at 2 different periods, before (acute period) and after (chronic period) pacemaker implantation. In the acute period, the QRS and heart rate during the escape rhythm were not significantly different between the 2 groups; however, the QT and QTc intervals were significantly longer in the TdP(+) group than in the TdP(-) group: 753 +/- 57.5 vs 635 +/- 78.4 ms (p less than 0.01) and 585 +/- 44.8 vs 476 +/- 58.3 ms (p less than 0.01). In the chronic period (greater than 2 months after pacemaker implantation), we changed the pacemaker rate from 90 or 100 beats/min to 50 beats/min and examined the QT interval changes in relation to the heart rate. The QT interval in the TdP(+) group was significantly prolonged compared with the TdP(-) group when the pacing rate was decreased less than or equal to 60 beats/min: 551 +/- 40 vs 503 +/- 36 ms at 60 beats/min (p less than 0.05), and 700 +/- 46 vs 529 +/- 43 ms at 50 beats/min (p less than 0.001). Patients with complete atrioventricular block with TdP had a bradycardia-sensitive repolarization abnormality and this characteristic remained after pacemaker implantation. The critical heart rate that induced abnormal QT prolongation in the TdP(+) group was less than or equal to 60 beats/min.

Adult↗
PubMed1992

Effects of a combination of disopyramide and mexiletine on the anterograde accessory pathway conduction in patients with Wolff-Parkinson-White syndrome.

In order to evaluate the electrophysiological effects of the combined administration of disopyramide and mexiletine on anterograde accessory pathway conduction, we studied 11 patients with Wolff-Parkinson-White (WPW) syndrome. Disopyramide was first infused intravenously at 1 mg kg-1 for 5 min followed by a continuous infusion at 0.025 mg kg-1 min-1. After the infusion rate of disopyramide was decreased to 0.004 mg kg-1 min-1 to maintain a lower serum concentration, mexiletine was infused at 2 mg kg-1 for 5 min followed by a continuous infusion at 0.008 mg kg-1 min-1 (protocol 1). The shortest atrial paced cycle length with 1:1 anterograde accessory pathway conduction (shortest CL with 1:1) and the anterograde effective refractory period of the accessory pathway (ERP) were measured: (1) before drug administration, (2) after disopyramide was given alone, and (3) after disopyramide and mexiletine were combined at lower concentrations. The same protocol was repeated with the order of drug administration reversed (mexiletine followed by disopyramide) in all patients (protocol 2). Both disopyramide and mexiletine lengthened the shortest CL with 1:1 and the ERP to the same degree. The combination of disopyramide and mexiletine at lower concentrations further lengthened the shortest CL with 1:1. It was longer than with disopyramide (protocol 1) or mexiletine (protocol 2) alone [protocol 1: 412 +/- 169 ms (combination) vs 356 +/- 117 ms (disopyramide); P less than 0.05, protocol 2: 409 +/- 166 ms (combination) vs 355 +/- 119 ms (mexiletine); P less than 0.01].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Significance of ventricular pacing site in manifest entrainment during orthodromic atrioventricular reentrant tachycardia with left-sided accessory pathway.

We examined entrainment by ventricular pacing in six patients during orthodromic atrioventricular reentrant tachycardia (AVRT) utilizing a left-sided lateral accessory pathway. Constant fusion and progressive fusion were demonstrated in all patients by left ventricular pacing during tachycardia, but in none of the patients by right ventricular pacing. When left ventricular pacing was performed during AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous pacing beat (n - 1) within the ventricle, therefore, constant fusion and progressive fusion were demonstrated in the surface electrocardiographic QRS complexes. On the other hand, when right ventricular pacing was performed during orthodromic AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous paced beat (n - 1) within the normal atrioventricular pathway, and constant fusion and progressive fusion were therefore not demonstrated. These phenomena were explained by the relationship of the ventricular pacing site and the reentrant circuit. This study demonstrates the importance of the pacing site in manifest entrainment of orthodromic AVRT during ventricular pacing.

Adult↗
PubMed1992

Spectral analysis of signal-averaged electrocardiograms in patients with idiopathic ventricular tachycardia of left ventricular origin.

BACKGROUND: The signal-averaged ECG has been used to detect late potentials, and it is considered a noninvasive marker for areas of slow conduction requisite for reentrant arrhythmia. Late potentials are not usually found in patients with idiopathic ventricular tachycardia (VT); nevertheless, fragmented electrograms are often recorded in those patients during endocardial mapping. The purpose of this study was to investigate the spectral content of the signal-averaged ECGs with use of fast Fourier transform analysis (FFT) in patients with idiopathic VT of left ventricular origin. METHODS AND RESULTS: Signal-averaged ECGs were recorded in 12 patients with idiopathic VT originating from the left ventricle (group 1) and 25 age-matched normal volunteers (group 2). Frequency analysis with FFT was performed with a Blackman-Harris window in a segment length of 120 msec from 40 msec before the end of the QRS complex, and the frequency spectrum was displayed in a three-dimensional graph. Area ratio 1 (area of 20-50 Hz/area of 10-50 Hz) and area ratio 2 (area of 40-100 Hz/area of 0-40 Hz) were calculated in all subjects. Late potentials defined by the time domain were negative in all subjects. The area ratios of group 1 were significantly higher than those of group 2. High-frequency components in the three-dimensional graph were confined within the QRS complex. CONCLUSIONS: These results suggest that frequency analysis of signal-averaged ECGs with FFT is an available method for detecting the high-frequency component within the QRS complex in some patients with idiopathic VT of left ventricular origin.

Adult↗
PubMed1991

Early afterdepolarizations induced by isoproterenol in patients with congenital long QT syndrome.

BACKGROUND: Several recent experimental and clinical studies have shown that early afterdepolarizations (EADs) are important in the genesis of QTU prolongation and ventricular tachyarrhythmias (VTs) in patients with long QT syndrome. On the other hand, sympathetic stimulation is well known to contribute to the genesis of QTU prolongation and VTs in patients with congenital long QT syndrome. The present study was performed to examine the influence of isoproterenol on the genesis of EADs and on the action potential durations and QTU intervals in patients with congenital long QT syndrome. METHODS AND RESULTS: We recorded monophasic action potentials (MAPs) with a contact electrode during right atrial pacing at a constant cycle length of 500 msec before and after continuous isoproterenol infusion (1 microgram/min). MAPs were obtained from the right and left ventricular endocardium in six patients with congenital long QT syndrome (LQT group, 18 recording sites) and in eight control patients (control group, 19 recording sites). Although no EADs were recorded from either group during the control state, MAP duration at 90% repolarization (MAPD90) was significantly longer in the LQT group (n = 18) than in the control group (n = 19) (275 +/- 36 versus 231 +/- 22 msec; p less than 0.0005). Isoproterenol induced EADs in four of the six LQT patients (five of 18 recording sites) but not in the eight control patients (zero of 19 recording sites). The appearance of EADs in the LQT group was associated with an increased amplitude of the late component of the TU complex, and the corrected QT (QTc) interval was prolonged by isoproterenol from 543 +/- 53 to 600 +/- 30 msec 1/2 (n = 6; p less than 0.05). Isoproterenol also prolonged the MAPD90 from 275 +/- 36 to 304 +/- 50 msec in the LQT group (n = 18; p less than 0.005), whereas it shortened the MAPD90 from 231 +/- 22 to 224 +/- 25 msec in the control group (n = 19; p less than 0.05). Moreover, isoproterenol increased the dispersion of MAPD90 (difference between the longest MAPD90 and the shortest MAPD90 in each patient) from 30 +/- 5 to 62 +/- 35 msec in the LQT group (n = 6; p = 0.08), whereas it did not change the dispersion of MAPD90 in the control group (n = 8; 25 +/- 14 versus 27 +/- 14 msec). CONCLUSIONS: These results suggest that patients with congenital long QT syndrome have primary repolarization abnormalities and that EADs induced by isoproterenol play an important role in the exaggeration of these repolarization abnormalities.

Action Potentials↗