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1.
AIMS: The aim of the study was to determine the value and correlation between QT dispersion, daily variations in the QT interval and late potentials as risk markers for ventricular tachycardia. METHODS AND RESULTS: QT dispersion was defined as the difference between the longest and the shortest QT interval in 12 electrocardiographic leads, QTc variability as the difference between the maximal and minimal QTc interval during 24-h Holter monitoring and QT interval adaptation as the regression line between heart rate and the uncorrected QT interval. One hundred and forty-five patients, 3 months after myocardial infarction were included in the study. QT dispersion significantly increased with the severity of arrhythmia (modified Lown's classification; P< 0.001). The level of 80 ms was associated with ventricular tachycardia with a sensitivity of 72.7% and a specificity of 86.4%. The greater daily variability of the QTc interval in patients with ventricular tachycardia was insignificant (P > 0.05). QT interval adaptation did not discriminate between patients with ventricular tachycardia from those in other groups. Late potentials were associated with ventricular tachycardia with a sensitivity of 50% and a specificity of 90.3%. CONCLUSION: Large QT dispersion and late potentials were risk markers for ventricular tachycardia, but there was no correlation between QT dispersion, daily variations in the QT interval and late potentials in patients 3 months after myocardial infarction.  相似文献   

2.
INTRODUCTION: Although intravenously administered procainamide has been used extensively during electropharmacologic testing for more than 10 years, there is little information available on the effects of incremental dosing of procainamide in patients with inducible, monomorphic ventricular tachycardia (VT). METHODS AND RESULTS: Twenty-nine patients with coronary artery disease had sustained monomorphic VT reproducibly induced in the baseline, drug-free state. Programmed stimulation was repeated 5 minutes after loading infusion (50 mg/min) of 7.5 and 15 mg/kg (all patients) and 22.5 mg/kg of procainamide (15 patients), while maintaining continuous infusion of 0.055, 0.11, and 0.165 mg/kg per minute after each increment in dose, respectively. Corresponding procainamide plasma concentrations were 5.6 +/- 2, 10.5 +/- 3, and 14.5 +/- 3 mg/L before, and 4.7 +/- 2, 9.6 +/- 3, and 14.6 +/- 4 mg/L after electrophysiologic study at each increment in dose of procainamide, respectively. Each incremental dose of procainamide resulted in significant prolongation of tachycardia cycle length and QRS duration during sinus rhythm and right ventricular pacing. Five (17%), 7 (24%), and 1 (7%) patients, respectively, had no inducible sustained VT following the incremental dosing of procainamide. Three of five patients who had no inducible VT at 7.5 mg/kg had VT induced again at a higher dose of procainamide. Four of 24 patients whose VT remained inducible at 7.5 mg/kg of procainamide had no VT induced at 15 mg/kg of procainamide. Twelve (41%), 15 (52%), and 6 (40%) patients, respectively, no longer had VT with baseline morphology induced following the incremental dosing of procainamide. VT with new morphology compared to baseline was induced in more than 40% of patients at one or more of the three different procainamide dosing regimens. The mean cycle length of VTs with new morphology was significantly shorter than the cycle length of tachycardias with baseline morphology at each particular dose of procainamide. CONCLUSION: Similar serum procainamide concentrations before and after programmed stimulation can be achieved at the described dosing regimen. Although 7.5 and 15 mg/kg of procainamide are both effective in suppressing induction of all VT in 20% to 25% of patients, non-inducibility at a particular dose of procainamide does not predict noninducibility at a respectively higher or lower dose. New morphologies of VT that are frequently faster than VTs with baseline morphology at a particular dose of procainamide can be induced in approximately half of the patients, and the clinical significance of these arrhythmias remains to be determined.  相似文献   

3.
Our objective was to evaluate the effect of exercise on QT dispersion over the next 3 hours, as seen on a standard 12-lead electrocardiogram in patients with healed myocardial infarction with or without residual ischemia. We measured QT and QTc dispersion before, immediately after, and 1 and 2 hours after symptom-limited, dynamic treadmill exercise tests in 28 patients with healed anterior wall myocardial infarction with (group I, n = 18) and without (group II, n = 10) residual ischemia. The same protocol was followed in 5 group I patients after successful performance of coronary angioplasty. QT and QTc dispersion did not change immediately after exercise in group II. These parameters increased in group I (QT dispersion at rest [mean +/- SD] 57 +/- 22 ms, and after exercise 87 +/- 27 ms; QTc dispersion at rest 62 +/- 25 ms, and after exercise 114 +/- 36 ms). The increases in QT and QTc dispersion were sustained for at least 2 hours. After a successful coronary angioplasty in 5 patients, these parameters no longer increased with exercise. Thus, QT dispersion increased for at least 2 hours after exercise in patients who had residual ischemia after healing of myocardial infarction. Data obtained in 5 of these patients after coronary angioplasty support the idea that residual ischemia plays a key role in the sustained increase in QT dispersion after exercise.  相似文献   

4.
OBJECTIVES: To describe the imaging features of nephroblastomatosis with US, CT and MR, to point out characteristics of differentiation between nephrogenic rests (NR) and Wilms' tumour (WT) and to determine the most appropriate imaging modality. MATERIALS AND METHODS: We reviewed the US, CT and MR images of 29 cases of histopathologically confirmed nephroblastomatosis sent to our department for reference evaluation (German nephroblastoma study). The series included 17 kidneys with NR, 6 kidneys with WT and 32 kidneys with both NR and WT. RESULTS: NR presented as multinodular, peripheral, cortical lesions, the diffuse form of distribution being less common. Foci were homogeneous and of low echogenicity, density or signal intensity. The lesions were most clearly depicted with contrast-enhanced CT and T1-weighted (T1-W) MR images. Lesions smaller than 1 cm were rarely identified by US. The most reliable criterion to differentiate NR from WT was their homogeneity. CONCLUSIONS: Contrast-enhanced CT and T1-W MR images are of similar potential and superior to US in the diagnosis of nephroblastomatosis. Due to the significant radiation dose of serial CT, MR imaging should be the method of choice wherever it is available. The cost-effectiveness and availability of US makes it ideal for serial follow-up of known lesions.  相似文献   

5.
OBJECTIVES: Increased QT dispersion has been considered as predisposing to ventricular arrhythmias in hypertrophic cardiomyopathy, congestive heart failure, and coronary artery disease. An increased QT dispersion has also been found in hypertensive patients with left ventricular hypertrophy (LVH). The data on the effect of LVH regression on QT dispersion are limited. METHODS AND RESULTS: To assess the relation of LVH regression and QT dispersion decrease, 68 patients (42 men and 26 women, mean age 56.3+/-9.5 years) with uncomplicated essential hypertension were studied. All underwent full electrocardiographic and echocardiographic studies at baseline and after 6 months of monotherapy, 29 with angiotensin-converting enzyme inhibitors and 39 with calcium antagonists. QT dispersion was calculated by subtracting the shortest QT from the longest QT, in absolute value (QTmax - QTmin). It was also corrected with Bazett's formula (QTc dispersion). Left ventricular mass index was assessed according to the Devereux formula. After treatment, LVH decreased with both angiotensin-converting enzyme inhibitors (from 155 to 130 g/m2, P < .001) and calcium antagonists (156 to 133/92/m2, P < .001). QT dispersion decreased both after angiotensin-converting enzyme inhibitor treatment (from 82 to 63 ms) and calcium antagonist treatment (from 77 to 63 ms, both P < .001 ). There was a significant correlation of QT dispersion and left ventricular mass after therapy (r = 0.36, P < .005). There was a correlation of the degree of LVH and QT dispersion decrease (r = 0.27, P < .05). CONCLUSIONS: It is concluded that LVH regression influences AQT favorably. Its prognostic value has yet to be determined.  相似文献   

6.
BACKGROUND: QT dispersion (QTd, equals maximal minus minimal QT interval) on a standard ECG has been shown to reflect regional variations in ventricular repolarization and is significantly greater in patients with than in those without arrhythmic events. METHODS AND RESULTS: To assess the effect of thrombolytic therapy on QTd, we studied 244 patients (196 men; mean age, 57 +/- 10 years) with acute myocardial infarction (AMI) who were treated with streptokinase (n = 115) or anistreplase (n = 129) at an average of 2.6 hours after symptom onset. Angiograms at 2.4 +/- 1 hours after thrombolytic therapy showed reperfusion (TIMI grade > or = 2) in 75% of patients. QT was measured in 10 +/- 2 leads at 9 +/- 5 days after AMI by using a computerized analysis program interfaced with a digitizer. QTd, QRSd, JT (QT minus QRS), and JT dispersion (JTd, equals maximal minus minimal JT interval) were calculated with a computer. There were significant differences in QTd (96 +/- 31, 88 +/- 25, 60 +/- 22, and 52 +/- 19 milliseconds; P < or = .0001) and in JTd (97 +/- 32, 88 +/- 31, 63 +/- 23, and 58 +/- 21 milliseconds; P = .0001) but not in QRSd (25 +/- 10, 22 +/- 7, 28 +/- 9, and 24 +/- 9 milliseconds; P = .24) among perfusion grades 0, 1, 2, and 3, respectively. Similar results were obtained comparing TIMI grades 0/1 with 2/3 and 0/1/2 with 3. Patients with left anterior descending (versus right and left circumflex) coronary artery occlusion showed significantly greater QTd (70 +/- 29 versus 59 +/- 27 milliseconds, P = .003) and JTd (74 +/- 30 versus 63 +/- 27 milliseconds, P = .004). Similarly, patients with anterior (versus inferior/lateral) AMI showed significantly greater QTd (69 +/- 30 versus 59 +/- 27 milliseconds, P = .006) and JTd (73 +/- 30 versus 63 +/- 27 milliseconds, P = .007). Results did not change when Bazett's QTc or JTc was substituted for QT or JT or when ANOVA included adjustments for age, sex, drug assignment, infarct site, infarct vessel, and number of measurable leads. On ANCOVA, the relation of QTd or JTd and perfusion grade was not influenced by heart rate. CONCLUSIONS: Successful thrombolysis is associated with less QTd and JTd in post-AMI patients. The results are equally significant when either QT or JT is used for analysis. These data support the hypothesis that QTd after AMI depends on reperfusion status as well as infarct site and size. Reduction in QTd and its corresponding risk of ventricular arrhythmia may be mechanisms of benefit of thrombolytic therapy.  相似文献   

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9.
INTRODUCTION: Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm. METHODS AND RESULTS: The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal intervals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds. CONCLUSION: Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.  相似文献   

10.
A 49-year-old woman was admitted because of several syncopes during sports activity. She was appeared well, and the physical examination revealed no pathological findings, particularly no heart murmurs. The electrocardiogram had a normal PQ, QRS and the corrected QT (QTc)interval was 0.44 s. During the exercise test no arrhythmias were seen and the QTc was unchanged of 0.44 s, but 0.6 mg atropine injected intravenously provoked prolonged QTc = 0.49 s followed by nonsustained ventricular tachycardia. Electrophysiological examination and coronary arteriography showed no inducible arrhythmias and no presence of coronary artery disease. Beta-blocker treatment was started. During one year of observation she presented no syncope, and was still active in sports. It is concluded that patients presenting with syncope and an ECG with borderline QT prolongation should undergo several provocation trials, if simple stress test is initially negative, because undiagnosed patients without prophylactic treatment have a high mortality.  相似文献   

11.
Acute ventricular septal rupture following myocardial infarction carries a high mortality. Early surgery improves survival but long term outcome depends on residual shunting and left ventricular function. Residual shunting is common despite apparently successful closure and may require reoperation. Transcatheter closure is an established method of treating selected congenital defects but clinical experience of transcatheter closure in postinfarction ventricular septal rupture is minimal. Transcatheter closure of a residual ventricular septal defect was successfully done using a new device, the Amplatzer septal occluder, in a 50 year old Indian man who had previously undergone emergency surgical repair for postinfarction acute ventricular septal rupture. The technique is described and its potential as a treatment in postinfarction ventricular septal rupture, its possible complications, and the important aspects of case selection and device design are discussed.  相似文献   

12.
AIMS: To evaluate the prognostic value of the QT interval and QT interval dispersion in total and in cardiovascular mortality, as well as in cardiac morbidity, in a general population. METHODS AND RESULTS: The QT interval was measured in all leads from a standard 12-lead ECG in a random sample of 1658 women and 1797 men aged 30-60 years. QT interval dispersion was calculated from the maximal difference between QT intervals in any two leads. All cause mortality over 13 years, and cardiovascular mortality as well as cardiac morbidity over 11 years, were the main outcome parameters. Subjects with a prolonged QT interval (430 ms or more) or prolonged QT interval dispersion (80 ms or more) were at higher risk of cardiovascular death and cardiac morbidity than subjects whose QT interval was less than 360 ms, or whose QT interval dispersion was less than 30 ms. Cardiovascular death relative risk ratios, adjusted for age, gender, myocardial infarct, angina pectoris, diabetes mellitus, arterial hypertension, smoking habits, serum cholesterol level, and heart rate were 2.9 for the QT interval (95% confidence interval 1.1-7.8) and 4.4 for QT interval dispersion (95% confidence interval 1.0-19-1). Fatal and non-fatal cardiac morbidity relative risk ratios were similar, at 2.7 (95% confidence interval 1.4-5.5) for the QT interval and 2.2 (95% confidence interval 1.1-4.0) for QT interval dispersion. CONCLUSION: Prolongation of the QT interval and QT interval dispersion independently affected the prognosis of cardiovascular mortality and cardiac fatal and non-fatal morbidity in a general population over 11 years.  相似文献   

13.
The efficacy of d/l sotalol was investigated in 50 patients (43 men, seven women; 33 with coronary artery disease, 15 with dilated cardiomyopathy; ejection fraction 33 +/- 10%) with inducible sustained ventricular tachycardia. Before d/l sotalol a mean of 2 +/- 1 (1 to 4) class I antiarrhythmic drugs were ineffective. In 24 patients (48%) oral d/l sotalol (320 +/- 47 mg.day-1) prevented induction of the ventricular tachycardia; in 23 patients the ventricular tachycardia remained inducible (d/l sotalol 326 +/- 50 mg.day-1). The electrophysiological effects of d/l sotalol did not differ between patients in whom d/l sotalol prevented induction of ventricular tachycardia and those in whom the ventricular tachycardia remained inducible. In two patients, torsade des pointes developed after oral application of d/l sotalol; one patient suffered from severe hypotension even with 80 mg of sotalol per day. During long-term follow-up (27 +/- 12 months) 5/24 patients (21%) had a non-fatal recurrence of ventricular tachycardia (1 week to 21 months), one patient died suddenly and another from progressive heart failure. In patients in whom the ventricular tachycardia could be induced despite oral application of d/l sotalol, control of the ventricular tachyarrhythmia was attempted by the use of sotalol in combination with mexiletine (n = 2), amiodarone (n = 9), catheter ablation (n = 2), antitachycardia surgery (n = 1) or the implantation of an automatic cardioverter defibrillator (n = 12). Recurrence of ventricular tachycardia was observed in four patients without an implanted cardioverter defibrillator. Seven out of 12 patients with an implanted cardioverter defibrillator received appropriate shocks or successful antitachycardia pacing. Although no patient died suddenly, overall mortality was 17% in this group. It is concluded that d/l sotalol is highly effective in the suppression of sustained monomorphic ventricular tachycardia inducible by programmed electrical stimulation. However during a mean follow-up of 27 +/- 12 months a recurrence of ventricular tachycardia was seen in 21% of patients, and one patient died suddenly.  相似文献   

14.
In order to characterize an alternative animal model for the study of diabetes mellitus type II onset, we compared the effects of a diet containing 8% of protein (LPD) and a normal diet containing 25% of protein supplied to the dams during the first 12 days of lactation. We studied in the pups the growth evolution and, when they develop into adults (60 days), the glucose tolerance test (GTT) and the insulin secretion, in response to stimulatory concentrations of glucose. The weight of the two groups were significantly different at 60 days of age (LPD = 179 +/- 19 g; NPD = 186 +/- 18 g). The GTT ten minutes after iv glucose administration showed a significant increase of blood glucose concentration of the LPD group (LPD = 550 +/- 17 mg/dl; NPD = 425 +/- 13 mg/dl, p < 0.001). The insulin secretion, four minutes after stimulation was found reduced in the LPD group (LPD = 1.1 +/- 0.08 muU/islet/min; NPD = 1.85 +/- 0.2 muU/islet/min.). The present study indicates insulin secretory and/or resistance impairment due to early undernutrition. Also, the data taken together suggest that undernutrition during early lactation can be used as an alternative model to study particular characteristics of the onset of diabetes mellitus type II.  相似文献   

15.
Resting L1210 cells were treated with nimustine (ACNU), a bifunctional alkylating anticancer agent, for 2 h in a nutrient-depleted medium. The cells were then transferred to a fresh medium and incubated for a further 48 h. Functions of the cells thus prepared were examined in terms of the dye-exclusion of the membrane, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl] -2H-tetrazolium hydroxide, inner salt, sodium salt (XTT)-reducing ability of the mitochondria, and heat generation due to vital metabolism as the measure of cell viability. The cells treated with ACNU were functioning normally in all the cell functions examined but were completely devoid of proliferating capacity. These results suggest the possibility that ACNU might impair the proliferative capacity of the resting cell population inside a solid tumor without causing such impairment to the cells of normal organs and tissues composed of intrinsically non-proliferative cells.  相似文献   

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This report deals with two patients who suffered sustained episodes of torsade de pointes ventricular tachycardia while using the novel antimalarial drug halofantrine. Both patients had congenital long QT syndrome, and their QT interval was further prolonged at the time of the event. This first electrocardiographic documentation of ventricular arrhythmias together with halofantrine's known prolonging effect on the QT interval demonstrates that the drug has the potential to induce life-threatening arrhythmias.  相似文献   

18.
The structure of UCH9, which is a novel antitumor agent, was determined by spectroscopic methods. UCH9 consists of an aglycone and five 2,6-dideoxy sugars (three D-olivoses, one 4-O-methyl-D-olivose and one D-oliose). Four of the five sugars are sequentially connected through a beta 1-->3 linkage (olivose-1-->3-4-O-methyl-olivose-1-->3-oliose-1-->3-+ ++olivose). On the basis of the results of spectroscopic analysis, it was found that UCH9 belongs to the aureolic acid family of antibiotics. The structure of UCH9 is unique in that mono- and tetrasaccharide moieties, and a long hydrophobic side chain (sec-butyl group) are attached to the aglycone, while di- and trisaccharide moieties and a methyl or a hydrogen are attached in the case of the known aureolic acid analogs. It is known that aureolic acid analogs from a dimer in the presence of Mg2+. NMR, FAB-MS and atomic absorption analysis revealed that UCH9 isolated from Streptomyces also forms a dimer, containing one equivalent molar Mg2+.  相似文献   

19.
Measurement of the QT dispersion (the maximal interlead difference) on the surface electrocardiogram has been suggested for assessing the risk for ventricular arrhythmias and for examining drug effects and their proarrhythmic potential. The acute response of QT dispersion was assessed in 10 healthy subjects receiving disopyramide, which is known to delay repolarization and to prolong global measures thereof. The QRS, JT, and QT intervals and their dispersion were assessed at spontaneous rhythm and at atrial pacing at baseline and after an intravenous injection of disopyramide 2 mg/kg over 5 minutes. The short-term (within 30 minutes) and long-term (> or = 2 weeks) variabilities of the QT interval and the QT dispersion, expressed as the coefficient of variation, were also analyzed. At spontaneous rhythm the group average QT interval was between 369 and 375 msec, and the QT dispersion was between 33 and 37 msec; both were relatively stable over time. All subjects responded homogeneously to disopyramide with a significant QT prolongation (p < 0.001), but no consistent response of the QT dispersion was observed. This discrepancy reflects the significant difference in time-dependent variability with a coefficient of variation of spontaneous, paced, and heart rate-corrected QT dispersion between 25% and 42%, 8-42 times greater than the corresponding values of 1-4% for the QT intervals. The individual response of the QT dispersion to drug challenge should therefore be interpreted with caution. Furthermore and as a consequence, QT dispersion is less sensitive for assessing drug effects on ventricular depolarization and repolarization than the QT interval.  相似文献   

20.
Twenty-four-hour acquisition of QT dispersion (QTd) from the Holter and the circadian variation of QTd were evaluated in 20 survivors of sudden cardiac death (SCD), in 20 healthy subjects, and in 14 control patients without a history of cardiac arrest who were age, sex, diagnosis and therapy matched to 14 SCD patients. Computer-assisted QT measurements were performed on 24-hour Holter recordings; each recording was divided into 288 5-minute segments and templates representing the average QRST were generated. QTd was calculated as the difference between QT intervals in leads V1 and V5 for each template on Holter. The 24-hour mean QTd was significantly greater in SCD patients (40 +/- 28 ms) than in healthy subjects (20 +/- 10 ms) and control patients (15 +/- 5 ms) (p <0.05). There was a circadian variation in QTd with greater values at night (0 to 6 A.M.) than at daytime (10 A.M. to 4 P.M.) in healthy subjects (25 +/- 13 vs 15 +/- 8 ms, p <0.001) and control patients (18 +/- 10 vs 12 +/- 4 ms p <0.05), whereas in SCD patients there was no significant difference between night and day values (45 +/- 31 vs 37 +/- 28 ms, p = NS). It is concluded that QTd measured by Holter was greater in SCD patients than in healthy subjects and matched control patients during the entire day. QTd has a clear circadian variation in normal subjects, whereas this variation is blunted in SCD patients. QTd measured on Holter differentiates survivors of cardiac arrest and may be a useful tool for risk stratification.  相似文献   

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