QT Dispersion Values Research Articles

IDENTIFICATION OF THE ELECTROCARDIOGRAPHIC PREDICTORS OF THE MYOCARDIAL ELECTRICAL INSTABILITY

The aim is to develop and clinical test of the novel computer program for the identification of the prognostic markers for sudden cardiac death. Among them are T-wave alternans, duration and dispersion of the interval QT, heart rate turbulence. Material and methods: 79 pts with cardiomyopathy and life-threatening ventricular arrhythmias and 30 pts without arrhythmias. The methods of the precision digital processing of the ECG signal are used. Results: The significantly higher values of T-wave alternans, QT dispersion and heart rate turbulence in pts with ventricular arrhythmias were obtained (p<0,01). Conclusion: The identification of the predictors of sudden cardiac death is necessary for timely risk stratification and choosing the treatment strategy in pts with cardiomyopathy.

QT Dispersion Measured by Automatic Computerized 12-Lead Electrocardiography Contributes Significantly to Detection of Left Ventricular Hypertrophy in Japanese Patients

This study assessed the diagnostic value of QT dispersion for left ventricular hypertrophy (LVH) as determined by echocardiography. The QT and QRS interval parameters were determined automatically using computerized 12-lead electrocardiography in 153 Japanese out-patients. Corrected QT dispersion (QTcD) and maximal QRS duration (MaxQRS) were significantly correlated with left ventricular mass index. The sum of QTcD and MaxQRS showed the highest correlation with left ventricular mass index among QT and QRS interval parameters and their combinations. The cut-off points for LVH discrimination in this study were different to those reported in Western, mainly Caucasian, populations, suggesting the need for ethnicity-specific LVH detection criteria. A scoring system derived from multiple logistic regression analysis, employing a combination of QTcD, QRS time-voltage product and ST-T change, showed a specificity of 86.3%. It was concluded that QTcD, in addition to QRS time-voltage product and ST-T change, improved the detection of LVH.

E0374 Comparison of treadmill exercise test and 99mTcMIBI18FFDG myocardial SPECT image for identifying viable myocardium in patients with old myocardial infarction

ObjectiveThe aim of this study was to investigate the correlation between myocardial viability in old myocardial infarction as assessed by treadmill exercise test and 99mTc-MIBI/18F-FDG dual isotope simultaneous acquisition of...

Assessment of QT Interval and QT Dispersion During Electroconvulsive Therapy Using Computerized Measurements

Electroconvulsive therapy (ECT) used in the treatment of severe psychiatric disorders induces stimulation of the autonomic nervous system with initial parasympathetic outflow immediately followed by a sympathetic response. These responses induce an initial bradycardia, arrhythmias, and hypertension. QT dispersion (QTD), defined as maximal QT interval minus minimal QT interval on 12 leads of the surface electrocardiogram, reflects regional heterogeneity of ventricular repolarization. The effects of electrical stimulus due to ECT on QT interval and QTD are of considerable interest. : This study was designed to investigate the effects of electrical stimulation caused by ECT on RR interval, QT interval, the rate-corrected QT (QTc) interval, QTD, and the rate-corrected QTD (QTcD) under general anesthesia using computerized measurements. Thirty psychiatric patients scheduled for ECT were studied under propofol anesthesia. A 12-lead electrocardiogram was monitored to measure parameters. Muscle paralysis was achieved by administering succinylcholine 1 mg/kg intravenously, and the efficacy of ECT was determined by the tourniquet technique. The RR interval and QT interval decreased significantly immediately after electrical stimulus, and returned to the baseline level 1 minute after electrical stimulus. In 25 out of 30 patients, the baseline value of QTc interval was higher than the normal limits, and the QTc interval decreased significantly for 2 minutes after electrical stimulus. In 27 out of 30 patients, the baseline values of QTD and QTcD were higher than the normal limits, and the QTD and QTcD increased significantly from immediately after electrical stimulus to 5 minutes after electrical stimulus. The QTc interval, QTD, and QTcD, which were associated with increased risks of ventricular arrhythmias, increased significantly before anesthetic induction in patients with major depression. Electrical stimulus during ECT induced further increases of the QTD and QTcD.

Alterations in QT dispersion in the surface electrocardiogram of female adolescent inpatients diagnosed with bulimia nervosa

Increased QT dispersion (QTd) reflects cardiac autonomic imbalance and indicates elevated risk for cardiac arrhythmias. In the present study, we assessed heart rate, QT and corrected QT intervals, and QTd in 20 acutely ill bulimia nervosa adolescent inpatients on admission and discharge. A significant decrease in QTd was found between admission and discharge (67 ± 13 milliseconds vs 55 ± 12 milliseconds, respectively; P = .0005). The decrease in QTd values correlated significantly with the decrease in the frequency of bingeing/purging behaviors ( r = 0.51, P = .022). No significant correlations were found between the electrocardiographic indices and other clinical and laboratory measures. The elevated QTd in malnourished bulimia nervosa patients might indicate a cardiac autonomic imbalance that is most likely corrected after symptomatic improvement.

The correlation between the plasma nitric oxide levels and QT/QTc interval in conscious rabbits

The current study was undertaken to investigate the effects of NOx (plasma concentrations of nitrate plus nitrite which are plasma nitric oxide (NO) metabolites) over QT interval and to determine the level of correlation between them in conscious rabbits. For this purpose, twenty-one New Zealand rabbits (5-7 months old) were used and randomly assigned into the following three groups: control (CG; n = 7, 1 ml isotonic NaCl solution per animal/day), L-arginine (ARG-G; n = 7, L-arginine solution 200 mg/kg/day) and L-NAME (NAME-G; n = 7, L-NAME solution 100 mg/kg/day). Injections were performed intraperitoneally at 9:00 a.m. for 9 days. Blood samples were collected 2 h after the injections on day 1, 5 and 9 and the concentration of plasma NOx was determined using a colorimetric method. ECG was also recorded 2 h after the injection on 1st, 5th and 9th days. The heart rate, QT intervals, corrected QT intervals (QTc) and QT dispersion (QTd), QTc dispersion (QTcd) values were calculated from the ECG recordings. Statistically significant differences were observed between HR, QT and QTc values in all groups for all days (p < 0.001). QTd and QTcd values were found statistically significant different in NAME-G compared to CG and ARG-G (p < 0.001). It was also determined that there was a statistically significant correlation between the NOx and HR and QT and QTc in all days. It is concluded from this study that NO is an important molecule for the electrical activation of heart and has effects on the duration of QT/QTc interval, which should be taken into consideration by the physicians. In addition, application of the L-arginine should be further studied.

A Simple ECG Marker for the Detection of Coronary Restenosis after Successful Coronary Angioplasty

The dynamic nature of QT dispersion (QTd) and the absence of an acceptable normal value suggest that the relative change not the absolute value of QTd would be a better predicator of coronary restenosis. We sought to examine the usefulness of the relative change in QTd, compared to the absolute value, as a predictor for coronary restenosis after previously successful percutaneous transluminal coronary angioplasty (PTCA). Ninety-two patients with a history of successful PTCA who were referred for coronary angiography (CA) for exclusion of coronary restenosis were included in this analysis. QTd was calculated as the difference in milliseconds between the maximum and minimum QT interval in the 12-lead ECG. Relative change in QTd was measured as [QTd at the time of angiography (current) - QTd after the successful PTCA (baseline)]/QTd (baseline) %. Receiver operating characteristics (ROC) analysis was used to detect the best cut-off point and also to compare the diagnostic accuracy of the relative change in QTd vs. the absolute QTd for prediction of coronary restenosis. The relative change in QTd showed a significantly larger ROC area under curve (AUC) compared to the absolute QTd [AUC (95% CI): 0.79 (0.698, 0.872) and 0.61 (0.498, 0.703) respectively; p=0.011 for AUCs comparison]. The best cut-off point for the relative QTd was 40%, and for the absolute QTd this was 50 ms. The sensitivity and specificity of > or =40% increase in QTd to detect coronary restenosis was 71% and 83%, with positive and negative predictive values of 90% and 57%, respectively. The diagnostic accuracy of the absolute value of QTd was much less than this; the sensitivity and specificity of QTd > or =50 ms were 48% and 58%, with positive and negative predictive values of 71% and 34%, respectively. Compared to the absolute value, the relative change in QTd is a better predictor of coronary restenosis after a previously successful PTCA. These findings may open the door for rethinking the use of QTd as a simple ECG predictor for cardiovascular outcomes.

Is valproate promising in cardiac fatal arrhythmias? Comparison of P- and Q-wave dispersion in bipolar affective patients on valproate or lithium–valproate maintenance therapy with healthy controls

Autonomic nerve system is considered to be involved in bipolar affective disorder (BAD) or to be influenced by valproate monotherapy or valproate plus lithium combination. We planned to assess the effects of medication on atrial and ventricular conduction. The electrocardiography records were performed with eligible 15 patients with valproate, 20 patients with lithium-valproate combination use in euthymic phases of BAD and 20 healthy participants. The blood valproate and lithium concentrations in groups were in normal range. The difference in P maximum, P minimum, maximum QTc were statistically insignificant. Minimum QTc (F = 6.36; df = 2; P = 0.003) and QT dispersion (QTD) (F = 5.57; df = 2; P = 0.006) were statistically significant among the groups. There were no significant differences between patient groups among ECG parameters. Minimum QTc was significantly longer in combination group than healthy controls, whereas the QTD values in both patient groups were significantly lower than controls'. Valproate might have some preventive effects on ventricular electrical conduction because of lower QTD in both patient groups. Thus, valproate seems to have cardiac conduction stabilizing effect beside its mood stabilizing aspect. However, this finding needs replication and further corroboration in well-designed studies.

Os efeitos da metformina sobre a dispersão do intervalo QT e QTc de ratos diabéticos

FUNDAMENTO: Diversos farmacos podem causar aumento do intervalo QT, bem como da sua dispersao (QTd) em registros eletrocardiograficos (ECG). O QTd pode ser um marcador potencialmente sensivel ao aumento do risco de arritmias cardiacas e morte subita cardiaca. Metformina e uma substância de eficacia anti-hiperglicemica utilizada no tratamento do diabete. Entretanto, estudos tem relacionado efeitos dose-dependentes da metformina sobre a glicemia e marcadores de riscos cardiovasculares. OBJETIVO: Avaliar os efeitos dose-resposta da metformina sobre o QT e QTd de ratos diabeticos. METODOS: Ratos Wistar machos foram distribuidos em cinco grupos: controle nao-tratado (C), diabetico nao-tratado (D), diabeticos tratados com metformina nas doses 3,5, 30 e 74 µg/kg/pc (DM 3,5, DM 30 e DM 74). O diabete foi induzido por uma injecao de aloxana (40 mg/kg, i.v.). O ECG foi registrado (1o, 15o e 30o dias) atraves de quatro eletrodos inseridos na camada subcutânea das patas. Ambos os intervalos, RR e QT, foram medidos, e entao os valores do QT corrigido e da dispersao de QT foram calculados. RESULTADOS: Os grupos DM 3,5 e DM 30 mostraram significativa reducao da glicemia (p< 0,05) quando comparados a alta dose (DM 74). Ratos do grupo DM 74 apresentaram aumento dos intervalos QTc, QTd e QTcd, enquanto os ratos dos grupos DM 3,5 e DM 30 apresentaram menor prolongamento desses intervalos. CONCLUSAO: A metformina em altas doses proporcionou maior dispersao do intervalo QT, em razao, provavelmente, do aumento da nao-homogeneidade do processo de repolarizacao ventricular, enquanto em baixas doses houve diminuicao do intervalo QT em ratos diabeticos.

Glue (Toluene) Abuse: Increased QT Dispersion and Relation with Unexplained Syncope

Exposure to toluene, one of the major components of glue, can lead to cardiac arrhythmias and sudden sniffing death syndrome. QT dispersion is a useful risk marker for cardiac arrhythmias and sudden cardiac death. The aim of this study was to investigate the effects of glue abuse on QT interval and QT dispersion. The study included 44 patients with inhalant abuse and 34 healthy controls. Patients were divided into three groups: glue abusers with history of unexplained syncope (n = 20), asymptomatic glue abusers (n = 24), and healthy control subjects (n = 34). QT intervals, QT dispersion, and corrected QT dispersion values were measured. QT and corrected QT duration were greater in the symptomatic group than in athe symptomatic group and greater in the asymptomatic group than in controls. QT and corrected QT dispersion in both symptomatic and asymptomatic group were significantly greater than controls (p= .001), and also QT and corrected QT dispersion in symptomatic group was greater in asymptomatic group (p = .001). These findings demonstrate that QT interval and corrected QT dispersion increase in symptomatic or asymptomatic toluene abusers. The QT and QTc dispersion were also found to be longer in the symptomatic group than those in the asymtomatic group.

QT Dispersion and Diastolic Functions in Differential Diagnosis of Primary Mitral Valve Prolapse and Rheumatic Mitral Valve Prolapse

There is no specific criteria established to guide physicians in the differential diagnosis of primary mitral valve prolapse (MVP) and rheumatic MVP. Previous studies suggested that history and pathology of mitral valve could be helpful in differential diagnosis of MVP. The aim of this study was to evaluate the value of QT interval, QT dispersion, and diastolic function in differential diagnosis of MVP. We examined electrocardiographies and echocardiographies of 24 primary MVP patients, 20 rheumatic MVP patients, and 21 healthy subjects. MVP was defined as superior displacement of the mitral leaflets more than 2 mm into the left atrium during systole. QT dispersion was significantly higher in primary MVP patients (71 +/- 13.5 ms, p < 0.01). Maximum QT dispersion value in rheumatic MVP patients was 55 ms. E and A velocity values which show ventricular early and late diastolic filling, were lower in primary MVP patients (p < 0.01). There was no difference in the heart rate corrected QT interval values between the primary MVP patients (397 +/- 28.1), rheumatic MVP patients (403 +/- 23.8) and healthy children (404 +/- 15.8; p > 0.05). Our findings may indicate that QT dispersion can be used as a parameter for differential diagnosis of primary MVP and rheumatic MVP. Further studies are needed to identify a cut-off point of QT dispersion.

Relation between QT dispersion, left ventricle systolic function and frequency of ventricular arrhythmias in coronary patients

QT dispersion (QTd) is a measure of non-homogeneous repolarisation of the myocardium and is used as an indicator of arrhythmogenicity. The aim of this study was to assess the relation between QT dispersion, left ventricle systolic function and frequency of ventricular arrhythmias in coronary patients. We studied 290 coronary patients, 72 with angina pectoris and 218 after myocardial infarction. Eighty-one coronary patients had frequent and complex ventricular arrhythmias (out of them 19 had ventricular tachycardia) and 209 were without arrhythmias or with infrequent ventricular premature contractions (VPC < or = 10/h). In all patients, QT dispersion, exercise test, 24-hour Holter monitoring and echocardiographic examination were performed. Patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd (71.8 +/- 25.5 vs 55.6 +/- 21.7 ms; p < 0.001), corrected QT dispersion (QTdc: 81.3 +/- 31.5 vs. 60.3 +/- 26.1 ms; p < 0.001 ), left ventricular end-diastolic diameter (LVEDd: 56.2 +/- 6.9 vs. 53.4 +/- 6.2 mm; p < 0.001) and left ventricular end-systolic diameter (LVESd: 39.5 +/- 6.2 vs. 36.0 +/- 6.3 mm; p < 0.001), and significantly lower values of left ventricular ejection fraction (LVEF: 47.7 +/- 13.9 vs. 55.9 +/- 11.6%; p < 0.001) in comparison to those without arrhythmias or with infrequent VPC. Patients with VT had significantly higher values of QTd and QTdc in comparison to other patients with frequent and complex ventricular arrhythmias (83.8 +/- 17.1 vs. 69.4 +/- 26.2 ms; p < 0.02 for QTd; 101.1 +/- 23.9: 77.6 +/- 31.4 ms; p < 0.005 for QTdc). There is a significant negative correlation of QTd and QTdc with LVEF, and a significant positive correlation of QTd and QTdc with inside dimensions of the left ventricle, in patients with frequent and complex ventricular arrhythmias. The study demonstrated that patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd and QTdc, as well as a higher degree of left ventricle systolic dysfunction in comparison to those without arrhythmias or with infrequent VPC.

Exercise Electrocardiogram Testing

Exercise testing remains the most widely accessible and relatively inexpensive method for initial evaluation of suspected coronary disease and for evaluation of its severity.1–3 Clinical usefulness has been limited, however, by poor sensitivity of standard ST-segment depression criteria for assessment of anatomic and functional coronary disease severity and for prediction of risk.1,2,4–6 Recent data make it clear that symptomatic obstructive plaques that typically result in exercise-mediated ischemia may be less relevant to infarction and sudden death than less obstructive unstable plaques.7 These limitations mandate a rethinking of the exercise ECG along 2 distinct lines: First, is it possible to improve the diagnostic value of the exercise ECG? Second, separate from its ability to diagnose obstructive coronary artery lesions, can the exercise test be used as a prognostic tool that can encourage effective prevention of premature deaths or coronary events? Both goals take us beyond the ST segment. Reversible ST-segment depression is the characteristic finding associated with exercise-induced, demand-driven ischemia in patients with significant coronary obstruction but no flow limitation at rest. This process differs from the flow-limited acute coronary syndromes because exercise-related ischemia is generally limited to the subendocardium and is proportional to increases in myocardial oxygen demand. Ventricular waveforms of the ECG can be related to the net uncanceled transmural gradients between endocardial and epicardial myocardium, as extrapolated from the work of Holland and Brooks, among others.8–10 Accordingly, isoelectric TQ and ST segments in normal and in nonischemic patients can be related to comparable resting membrane and action potential plateau voltages in endocardial and epicardial action potentials. During exercise, progressive ischemia results in changing endocardial action potentials during both diastole and systole. Less negative endocardial cell resting membrane potential leads to current flow across the ischemic boundary during diastole, leading to elevation of the TQ …

Uncomplicated Metabolic Syndrome Is Associated with Prolonged Electrocardiographic QTc Interval and QTc Dispersion

Metabolic syndrome is associated with increased risk of mortality and morbidity. The present study evaluates the repolarization abnormalities in patients with uncomplicated metabolic syndrome measuring corrected QT interval (QTc) and corrected QT dispersion (QTd) on electrocardiogram. The study involved 83 subjects. A total of 50 individuals met criteria of metabolic syndrome (Group A: 11 men, 39 women, mean body mass index (BMI) 36.7 kg/m2, mean waist circumference 117.3 cm). And 33 participants were healthy normal volunteers (Group B: 9 men, 24 women, mean BMI 21.3 kg/m2, mean waist circumference 76.2 cm). The two groups were matched for age and sex. Metabolic syndrome was diagnosed according to the Adult Treatment Panel III criteria. The QTc intervals and QTd were measured. Patients with uncomplicated metabolic syndrome had significantly higher values of QTc-min, QTc-max, and QTd than control group (P < 0.001). Patients with uncomplicated metabolic syndrome have a greater dispersion of ventricular repolarization time and increased QTc-min and QTc-max.

Role of Shortened QTc Dispersion in In-hospital Cardiac Events in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome

QT dispersion (QTD) refers to the difference between maximal and minimal QT values on the electrocardiogram (ECG). QTD values are calculated and corrected with Bazett's formula (corrected QTD = QTcD = QTD/square root of RR). QTcD increases in patients with acute coronary syndrome (ACS). Recovery of increased QTcD (shortened QTcD) develops after successful revascularization, but prolonged QTcD occurs in certain patients. The aim of this study is to ascertain the clinical significance between shortened and prolonged QTcD groups after percutaneous coronary intervention (PCI). We retrospectively enrolled 128 patients with ACS who had received PCI. The values of QTcD were measured manually on 12-lead standard ECGs obtained within 3 days before and after PCI (pre-PCI QTcD and post-PCI QTcD). All the patients were divided into 2 groups. The shortened QTcD group was defined as those patients with a decrease in QTcD after PCI and the prolonged QTcD group as those with an increase in QTcD after PCI. The underlying diseases, various clinical classifications and some prognostic factors were taken into comparison and statistical analysis between these 2 groups. The shortened QTcD group showed a significantly higher rate of in-hospital cardiac death (13% vs. 0%, p = 0.006) and a greater pre-PCI QTcD (100.8 +/- 39.5 vs. 61.3 +/- 24.1 ms, p < 0.001) than the prolonged QTcD group. There was a significantly greater pre-PCI QTcD in patients with cardiac death than those without cardiac death (111.6 +/- 38.3 vs. 83.3 +/- 38.3ms, p = 0.027). Furthermore, the patients with in-hospital cardiac death presented with a significantly more frequent occurrence of in-hospital ventricular arrhythmia, compared with those without cardiac death (30.0% vs. 4.0%, p = 0.014). Among the patients with ACS undergoing PCI, directly divided into shortened and prolonged QTcD groups regardless of initial pre-PCI QTcD, the shortened QTcD group showed a higher occurrence of in-hospital cardiac death and a greater pre-PCI QTcD. Shortened QTcD might be 1 risk factor for in-hospital cardiac death.

QT dispersion in comparison to Tl-201-SPECT for detection of myocardial ischaemia

Objective There is controversy whether the measurement of QT dispersion might provide information about the presence and extent of ischaemic myocardium. It was the aim to analyse the diagnostic value of QT dispersion for the detection of myocardial ischaemia in comparison to Tl-201-SPECT. Patients and methods 100 patients were randomly selected from patients referred for Tl-201-SPECT. QT duration was measured in all 12 leads in the resting ECG and in the ECG either at maximal bicycle exercise or during peak dipyridamole stress. QT dispersion was calculated and correlated with parameters of ischaemia for all patients and for the bicycle exercise and the dipyridamole group separately. Results 25 patients had to be excluded from the analysis because QT dispersion could not be measured. Regression analysis did not show significant correlation neither for all 75 patients nor for the bicycle exercise nor for the dipyridamole group correlating grade of myocardial ischaemia, number of ischaemic segments and summed ischaemic stress score with QT dispersion in the resting or the stress ECG and QTd and there was no significant difference between groups. Conclusion QT dispersion could not be measured in 25/100 patients (25%). In the remaining patients QT dispersion did not correlate with the extent or grade of myocardial ischaemia.

Effects of Carvedilol Therapy on Arrhythmia Markers in Patients With Congestive Heart Failure

The aim of this study was investigate the effects of carvedilol therapy on ventricular repolarization characteristics as assessed by QT dispersion (QTd) and heart rate variability (HRV) in patients with heart failure. Thirty-one patients with heart failure (mean age, 63.9 years) were included in the study. Carvedilol was administered in addition to standard therapy for CHF at a dose of 6.25 mg/day and uptitrated to the maximum tolerated dose. Control group consisted of 14 patients with heart failure (mean age, 69.4 years) who could not take carvedilol due to several reasons. All patients were followed-up 6 months. QT dispersion (QTd), and corrected QTd (QTcd) values were calculated at baseline and at the end of follow-up. Time domain and frequency domain heart rate variability analysis were performed with ambulatory Holter ECG. Mean carvedilol dose was 23.9 +/- 13.9 mg. Significant reductions were observed in the QTd (P = 0.016) and QTcd (P = 0.001) with carvedilol therapy, whereas QTd (P = 0.47) and QTcd (P = 0.43) did not change significantly in the control group. The QT maximum value did not change significantly but the QT minimum value (P = 0.03) was significantly increased after carvedilol therapy. Although the mean SDANN value was improved (P = 0.039), other HRV parameters such as mean SDNN (P = 0.32), rMSSD (P = 0.74), and the LF/HF ratio (P = 0.35) did not change significantly after carvedilol therapy. This prospective controlled study shows that carvedilol therapy decreased QT dispersion and improved ventricular repolarization characteristics but did not change autonomic dysfunction in patients with heart failure.

Effects of Methadone on QT-Interval Dispersion

To evaluate the effects of methadone on QT-interval dispersion. Single-center, prospective, cohort study. Methadone maintenance treatment facility. One hundred eighteen patients who were newly admitted to the facility. Intervention. Twelve-lead electrocardiograms (ECGs) were performed in patients at both baseline and 6 months after the start of methadone therapy. The ECGs were manually interpreted, and investigators were blinded to time interval and methadone dose. At least eight discernible ECG leads were required for study inclusion. Mean differences between baseline and follow-up rate-corrected QT (QTc) interval and QT dispersion were compared. Multivariate associations between clinical characteristics and magnitude of change in QT dispersion were assessed using linear regression. Mean +/- SD baseline QT dispersion was 32.9 +/- 12 msec, which increased to 42.4 +/- 15 msec (+9.5 +/- 18.6 msec, p<0.0001) after 6 months of therapy. The QTc increased by a similar magnitude (+14.1 msec, p<0.0001). No QT dispersion value exceeded 100 msec. The only variable associated with a greater increase in QT dispersion was antidepressant therapy (20 vs 8.5 msec, p=0.04). Methadone modestly increased both QTc interval and QT dispersion. Increased QT dispersion reflects heterogeneous cardiac repolarization and occurs with nonantiarrhythmic agents, such as synthetic opioids. However, the magnitude of this effect appears to be substantially less with methadone than with antiarrhythmic drugs.

QT Interval Analysis in Patients With Acute Biliary Pancreatitis

It has been previously proposed that electrocardiographic abnormalities may be associated with acute pancreatitis. However, there is a lack of data on the QT interval and dispersion value in patients with acute pancreatitis, and no data are also available concerning QT interval and QT dispersion in acute biliary pancreatitis (ABP). : We aimed to investigate the QT parameters in patients with ABP, to compare them with those of healthy controls, and to analyze the relationship between QT parameters and Ranson score. The present study included 32 patients with acute biliary pancreatitis and 35 healthy controls. The severity of the pancreatitis was determined by Atlanta criteria: fewer than 3 Ranson criteria or fewer than 8 APACHE II (the Acute Physiology and Chronic Health Evaluation) points indicated the mild disease (group 1); 3 or more Ranson criteria or 8 or more APACHE II points or organ failure or systemic complications or local complications indicated the severe disease (group 2). On admission, all patients underwent a standard 12-lead electrocardiogram, and corrected maximum QTc interval (QTcmax), corrected minimum QT interval (QTcmin), and corrected QTc dispersion (QTcd) values of the subjects were measured according to the Bazett formula in this study. QTcmax and QTcd were significantly longer in patients with ABP than in healthy controls (442 +/- 38 milliseconds versus 413 +/- 34 milliseconds, P < 0.05; and 67 +/- 21 milliseconds versus 42 +/- 18 milliseconds, P < 0.001, respectively). Similarly, QTcmax and QTcd were significantly longer in group 2 than in group 1 (440 +/- 38 milliseconds versus 450 +/- 34 milliseconds, P < 0.01; and 66 +/- 9 milliseconds versus 71 +/- 11 milliseconds, P < 0.01, respectively). Correlation analysis showed that there is a significant positive relationship between Ranson scores of patients and QTcmax and QTcd (P < 0.01 and P < 0.001, respectively). The effect of acute biliary pancreatitis on QT intervals and dispersion appears to be dependent not only on the disease but also on its severity, and these parameters may give additional prognostic information in ABP patients, even in the initial evaluation.

Acute alcohol intake and QT dispersion in healthy subjects.

QT dispersion (QTd) is the maximal interlead difference in the QT interval on the surface 12-lead electrocardiogram (ECG). An increase in QTd is found in patients with various cardiac diseases and reflects cardiac autonomic imbalance. Variability of QT duration among the 12 surface ECG leads expresses electrical instability and greater susceptibility to malignant ventricular arrhythmias. Electrophysiological studies have shown that heavy episodic drinking facilitates the induction of ventricular tachyarrhythmias in some heavy drinkers. However, the association between QTd and acute alcohol intake has not been studied previously in healthy subjects. In a randomized crossover study, 10 healthy male volunteers (average [SD] age 30 [2.1] years, range: 25-33) received either alcohol (six 12-oz cans of beer) or placebo (juice). The alcohol group consumed 0.97 [0.12] g/kg body weight ethanol, and the placebo group consumed the same amount of juice in a 1-hour period. After a 48-hour washout period, the alcohol group drank juice, and the juice group drank alcohol. QTd and corrected QTd (cQTd) were measured in a baseline ECG after the alcohol period (AP) and after the juice period (JP). In comparison with baseline ECG (31.7 [9.4] ms), QTd values after AP (42.1 [10.8] ms) were significantly prolonged (p = .027), but this was not so after JP (33.8 [7.1] ms; p = NS). Also in comparison with baseline ECG (35.7 [11.1] ms), cQTd values after the AP (49.8 [12.7] ms) were significantly prolonged (p = .005), but again, this was not so after the JP (36.8 [7.3] ms; p = NS). Heavy episodic drinking is associated with an increase in QTd and cQTd.