Particle spectrum in gluon jets produced in e+e- annihilations at sqrt s around 58 GeV.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
H Takaki
Publications and source records attributed to H Takaki.
Increase in peak oxygen uptake by restoration of atrial contraction in patients after percutaneous transvenous mitral commissurotomy.
The aim of the present study was to determine the effect of sinus conversion after mitral commissurotomy on the exercise performance of patients with mitral stenosis (MS) and atrial fibrillation (Af). Electric cardioversion was attempted 10 days after successful balloon mitral commissurotomy in 32 patients with MS and Af. Both symptom-limited exercise tests with respiratory gas analysis and constant workload exercise tests with echo-Doppler examinations were performed before, five days and three months after mitral commissurotomy, and five days after successful sinus conversion. The balloon commissurotomy attenuated the increase in transmitral pressure gradient during exercise. However, no significant increase either in peak oxygen uptake (PVO2) or stroke volume were observed even three months after commissurotomy in patients with persistent Af. Sinus conversion was successful in 17 patients and PVO2 increased from 21.4 +/- 4.1 to 23.4 +/- 4.0 ml/min/kg (p < 0.01). The extent of the increase in PVO2 was related to the atrial contribution in transmitral flow (R2 = 0.39, y = 0.81x + 1.2). Sinus rhythm was maintained for three months in 14 of 17 patients. Increased PVO2 was also preserved in these patients. These results suggest that the sinus conversion after mitral commissurotomy has an effect on the exercise performance of patients with MS and Af.
Adult↗
Geographic distribution of physicians in Japan.
In the 1970s, Japan's physician manpower policy was to increase the number of medical students and medical schools to ease the difficulties caused by shortage of doctors and their maldistribution. 34 medical schools were established during this time, which eventually doubled the number of newly certificated physicians from about 4000 to about 8000 per year by the mid 1980s. To examine the success of this policy, we analysed the numbers of physicians in relation to the population in all municipal bodies (n = 3268) in Japan. Between 1980 and 1990, the number of practising physicians increased by about 37%, and the ratio of physicians per 100,000 population increased from 127 to 165 throughout the country. However, analyses by the Lorenz curve and the Gini coefficient indicated that the inequality in physician distribution did not improve. While municipal bodies with a population over 30,000 gained proportionally more physicians, most communities with fewer than 10,000 residents showed little gain. Our findings have important implications for policy changes now being considered by the government to plan the future supply of physician manpower in Japan. A policy that will alleviate physician maldistribution also needs to be devised.
Education, Medical↗
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↗
[Percutaneous transluminal angioplasty of dialysis access shunts].
Sixteen balloon angioplasties were performed in 10 patients with upper-extremity dialysis access shunts. The initial success rate was 80% (12/15). Of the initial successes, 58% (7/12) were patent at six months and 13% (1/8) at one year. In nine cases, repeat PTA was necessary. The mean interval of patency was about four months. The longest interval was two and a half years. The complication of thrombosis of the loop shunt during PTA was successfully treated by fibrinolytic therapy.
Adult↗
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↗
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↗
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↗
Quantitative assessment of coronary artery stenosis by intravascular Doppler catheter technique. Application of the continuity equation.
BACKGROUND: Quantitative assessment of coronary artery stenoses plays a central role in clinical decision making. According to the continuity equation, the ratio of the time-velocity integral of prestenotic to stenotic flow velocities represents the ratio of the cross-sectional area of the stenotic to prestenotic segments. However, no data exist regarding the application of this method to clinical assessment of human coronary artery diseases. Therefore, we attempted to determine the severity of coronary artery stenoses by applying the continuity equation to the coronary circulation. METHODS AND RESULTS: Nineteen patients with a stenosis of the proximal left anterior descending coronary artery (LAD) and one patient with a stenosis in an aortocoronary bypass graft to the LAD were studied. Coronary flow velocities at the prestenotic and stenotic segments were measured with an end-mounted Doppler catheter (3F, 20 MHz), and the time-velocity integral ratio was calculated. Percent area stenosis was calculated as (1-time-velocity integral ratio) x 100. In three patients with severe stenosis (greater than 90% in area stenosis), velocity at the stenosis could not be determined because of aliasing of Doppler signals, and in four, Doppler signals at the stenosis were not measurable because of technical difficulties. The stenotic flow velocity was successfully recorded in 13 patients (65%) with mild to moderate stenosis. The diastolic peak flow velocity at the stenosis was 90 +/- 36 cm/sec (mean +/- SD), and was significantly greater than the velocity at the prestenotic segment, 48 +/- 18 cm/sec (p less than 0.01). Percent area stenosis determined by Doppler continuity equation correlated closely with that by biplane coronary angiography (r = 0.83, y = 0.92x-0.45, p less than 0.01). CONCLUSIONS: Application of the continuity equation to Doppler catheter measurement of coronary flow velocity can be used to successfully compute the severity of coronary stenoses. This may be a useful alternative method to estimate functional severity of coronary artery disease, although further technical developments will be necessary to improve the sensitivity.
Aged↗
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↗
[Comparison of exercise capacity evaluated by cardiopulmonary exercise test and hemodynamic parameters in patients with atrial septal defect].
We evaluated the maximal exercise tolerance using cardiopulmonary exercise testing, and investigated the relation of the hemodynamic parameters such as mean pulmonary artery pressure (PAm) and pulmonic-to-systemic flow ratio (Qp/Qs) to exercise tolerance in 18 adult patients consecutively. All the patients had atrial septal defect (ASD). Maximal oxygen uptake (VO2 max) averaged only 21.6 +/- 5.6 ml/min/kg and 63.5 +/- 16.2% of the predicted values (VO2max). And anaerobic threshold averaged 12.5 +/- 2.3 ml/min/kg and 56.7 +/- 12.4% of the predicted values. There were 2 patients who had marked pulmonary hypertension (PH, PAm more than 44 mmHg). Maximal exercise tolerance of these patients was severely impaired, and %VO2max was only 45.9% and 46.2% respectively. In patients without PH (PAm less than 20 mmHg), however %VO2 max ranged widely from 100.3 to 44.7% and PAm correlated with %VO2max weakly (r = -0.53, p less than 0.05). But there was a significant inverse relationship between Qp/Qs and %VO2max(r = -0.85, p less than 0.01). In 16 patients without PH, maximal O2-pulse during exercise was also inversely correlated with Qp/Qs (r = -0.76, p less than 0.01). The relation between PAm and %VO2max suggests that afterload on the right ventricle may be an important determinant of exercise capacity in patients with PH. And the relation between Qp/Qs and %VO2max or Qp/Qs and % maximal O2-pulse suggests that Qp/Qs may also be a very important determinant factor of exercise capacity in patients without PH.
Adult↗
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↗
[Age-related changes in clinical and prognostic significance of exercise-induced angina].
Exercise-induced angina (EA) is an important manifestation of myocardial ischemia in stress testing. However, whether or not the presence of EA indicates a greater severity and worse prognosis of coronary artery disease is uncertain. It is well known that the elderly have a greater prevalence of silent myocardial infarction. This suggests that the incidence and significance of EA in elderly patients may differ from those in the younger patients. Therefore, we, at first, studied the age-related change in the incidence of EA by reviewing 983 consecutive treadmill tests. Furthermore, to evaluate the age-related change of the clinical and prognostic significance of EA, exercise tests, angiographic findings and 29 months follow-up data were assessed in 142 patients without prior myocardial infarction who underwent treadmill test and coronary angiography (CAG) for the investigation of coronary artery disease. The rate of positive test results among 983 treadmill tests exceeded 30% only in patients 60 years old or older. Accordingly, we divided the patients into two different age groups: middle-aged patients (less than or equal to 59 yr, M-patients) and elderly patients (greater than or equal to 60 yr, O-patients). Among 983 treadmill tests, O-patients had a higher rate of positive results (presence of EA or positive ECG criteria) than M-patients (36 vs. 24%, p less than 0.001). However, incidence of EA was similar in the 2 groups (17 vs. 14%).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Does methylprednisolone potentiate the effects of dobutamine during thoracic epidural analgesia?].
The cardiovascular effects of dobutamine (DOB) combined with methylprednisolone (MP) were studied during thoracic epidural analgesia (TEA) in 59 patients undergoing operations on upper abdomen. To establish TEA, 8-10 ml of lidocaine 20 mg.ml-1 was injected into the epidural space through the T8-T9 interspace. The patients was intubated after fentanyl 0.2 mg, thiopental 3 mg.kg-1 and vecuronium 0.2 mg.kg-1. Anesthesia was maintained with 67% N2O, 33% O2 and 0.6% enflurane and DOB was infused at a rate of 5 micrograms.kg-1.min-1 during the surgical operation. Systolic blood pressure and urinary output after TEA did not decrease in the two groups, pretreated with MP 5 mg.kg-1 one hour or immediately before TEA, but decreased in the control group without MP injection. Heart rate showed no significant changes after TEA in all groups. We conclude that MP may potentiate the cardiovascular effects of DOB during TEA.
Anesthesia, Epidural↗
Narrow QRS complex tachycardia with atrioventricular dissociation.
We describe the case of a 22-year-old man who had frequent episodes of narrow QRS complex tachycardia with atrioventricular dissociation. The ECG during sinus rhythm showed normal PR and QRS intervals, but it showed a left bundle branch block configuration during atrial pacing or after injection of verapamil. An electrophysiological study demonstrated that the patient had nodoventricular Mahaim fibers. The narrow QRS complex tachycardia was explained by a circuit involving antegrade conduction via the atrioventricular nodo-His axis and retrograde conduction via the nodoventricular bypass tract.
Adult↗
Maladaptation after successful revascularization in anginal patients without transmural infarction.
In order to elucidate how peripheral or cardiac function maladaptations play a role in deconditioning after coronary bypass surgery, we have evaluated effects of successful coronary artery bypass grafting (CABG) and percutaneous transluminal angioplasty (PTCA) on exercise capacity in anginal patients without myocardial infarction. Symptom-limited treadmill exercise tests were performed in 46 patients before and after CABG and in 28 patients before and after PTCA. None of the patients carried out a cardiac rehabilitation program after their discharge. PTCA patients showed significant improvement of exercise capacity, from 6.4 +/- 1.6 to 10.5 +/- 2.5 METs in 4 weeks after PTCA, and even elderly PTCA patients showed improvement from 6.0 +/- 1.1 to 10.3 +/- 2.5 METs. However, the exercise capacity of CABG patients improved only from 5.9 +/- 1.4 to 8.5 +/- 3.1 METs in the first 6 months after CABG, and from 5.9 +/- 1.7 to 10.0 +/- 3.6 METs thereafter. The 15 elderly CABG patients showed only slight increase of physical activity, from 6.0 +/- 1.7 to 6.9 +/- 1.9 METs in the first 6 months after CABG and from 6.3 +/- 1.9 to 8.7 +/- 2.9 METs thereafter. Furthermore, 6 of 15 elderly CABG patients showed no improved exercise capacity after CABG. There was no correlation between the duration of anginal symptoms before CABG and exercise capacity before or after CABG. These findings suggest that CABG itself and/or physical restriction during admission produces peripheral function maladaptation and may be the main contributors to deconditioning after CABG, especially in elderly patients. This deconditioning can be treated by a rehabilitation program after the discharge.
Aged↗
[Utility of ST/HR slope and modified ST/HR score in the prediction of coronary artery disease in standard treadmill exercise test].
Explore the source record for details and available documents.
Adult↗
[Surgical treatment of total anomalous pulmonary venous return--evaluation of five successful cases].
Explore the source record for details and available documents.
Echocardiography↗