Determinants of electrocardiographic and spatial vectorcardiographic descriptors of ventricular repolarization in normal subjects.
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Adult↗
Biomedical subjects
J Gialafos
Publications and source records attributed to J Gialafos.
Non-sustained ventricular tachycardia due to low-dose orphenadrine.
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Electrocardiography, Ambulatory↗
Radiofrequency catheter ablation of posteroseptal accessory pathways--results of a step-by-step ablation approach.
INTRODUCTION: Transcatheter radiofrequency ablation of posteroseptal accessory pathways (AP) is challenging. A number of different interventional approaches have been suggested by different groups. The selection of the initial approach is crucial in order to reduce radiation exposure and the number of unsuccessful lesions applied. We present our ablation technique as guided by a simplified electrocardiographic analysis of the delta wave polarity and the electrophysiologic mapping results. METHODS AND RESULTS: Out of 35 manifest APs encountered in the right (n=17) or the left posteroseptum (n=18) in 35 patients, 34 were successfully ablated. Despite their left sided location, 7 of the 18 "left" sided APs were ablated after switching from an initial arterial to a venous approach looking for an appropriate target site in the right posteroseptal space or within the coronary sinus network. The other 11 left sided APs were ablated in the mitral ring, on 2 occasions, on their atrial aspect through a retrograde transmitral approach. On the contrary, 16 of the 17 "right" sided APs were successfully ablated exclusively through a venous approach. Fourteen of these were ablated in the right posteroseptum, in 2 cases, only after reaching their ventricular aspect. Two right sided APs were interrupted in the coronary sinus os and the middle cardiac vein respectively. CONCLUSION: It appears that even though the electrocardiographic and electrophysiologic location of the AP in the posteroseptal space helps select the appropriate initial approach, it does not always guarantee a successful ablation procedure in the expected site of the corresponding atrioventricular ring. Not uncommonly, it will be necessary to look after intermediate target sites within the coronary sinus to improve the overall ablation success rate.
Adolescent↗
The spatial QRS-T angle as a marker of ventricular repolarisation in hypertension.
Ventricular repolarisation abnormalities are important in arrhythmia provocation. The dispersion of repolarisation duration is not the only aspect of repolarisation heterogeneity. Spatial vectorcardiographic descriptors constitute a novel approach to quantify ventricular repolarisation. To test the ability of vectorcardiographic descriptors to discriminate between hypertensives with high or low blood pressure (BP), 110 treated hypertensives (mean age 63.6 +/- 12.1 years) were classified in the high (systolic BP > or = 160 mm Hg or diastolic BP > or = 95 mm Hg) (n = 67), or the low (systolic BP < 160 mm Hg and diastolic BP <95 mm Hg) (n = 43) BP group. The maximum QT, JT, and T peak-T end intervals and the QT, JT, and T peak--T end dispersion were calculated from a digitally recorded 12-lead electrocardiogram (ECG). X, Y, and Z leads were reconstructed from the 12-lead ECG. The amplitude of the maximum spatial T vector (spatial T amplitude), the angle between the maximum spatial QRS and T vectors (spatial QRS-T angle) and the frontal plane QRS-T angle were calculated. The spatial QRS-T angle was higher in patients with high compared to those with low BP (P = 0.025). All conventional ECG markers of the dispersion of ventricular repolarisation duration failed to demonstrate significant differences between hypertensives with high or low BP. In conclusion, the spatial QRS-T angle was significantly increased in those treated hypertensive patients who showed repeatedly high BP values. Hence, we may suggest that the angle between the directions of ventricular depolarisation and repolarisation is a sensitive marker of the repolarisation alterations in systemic hypertension. Journal of Human Hypertension (2001) 15, 63-70
Aged↗
Spatial aspects of ventricular repolarization in postinfarction patients.
QT dispersion has been proposed to reflect the heterogeneity of ventricular repolarization, but a poor reproducibility limits its clinical usefulness. Spatial vectorcardiographic descriptors constitute a novel approach to quantify ventricular repolarization. To test the ability of vectorcardiographic descriptors to discriminate among different subsets of postinfarction patients, 50 consecutively recruited patients with acute MI, 50 patients with history of an old (> 6 months) MI, and 50 healthy controls were evaluated. The maximum and minimum QT and JT intervals and QT and JT dispersion were manually measured from a digitally recorded 12-lead ECG. X, Y, and Z leads were reconstructed from the 12-lead ECG. The amplitude of the maximum spatial T vector (spatial T amplitude), the angle between the maximum spatial QRS and T vectors (spatial QRS-T angle), and the frontal plane QRS-T angle were automatically calculated. The spatial T amplitude and the spatial QRS-T angle did not differ between patients with a recent and those with an old MI (P = 1). QT dispersion was significantly lower in patients with an old MI than in patients with a recent one (P = 0.002). The spatial repolarization descriptors showed better short-term reproducibility than the dispersion indices. In conclusion, the spatial T amplitude and the spatial QRS-T angle are accurate measures of ventricular repolarization that do not differ between patients with recent and those with old MI. The different QT dispersion values observed in this study between the two post-MI groups should be considered cautiously because of the low accuracy of the manual measurements.
Case-Control Studies↗
The effects of cigarette smoking on the heterogeneity of ventricular repolarization.
BACKGROUND: Although the circulatory effects of cigarette smoking have been studied extensively, its impact on ventricular repolarization has not been adequately evaluated. METHODS: The goal of our study was to determine whether cigarette smoking influences the spatial and temporal heterogeneity of ventricular repolarization in a population of young, healthy, male subjects. A digital 12-lead surface electrocardiogram was obtained from 1394 men recruited from the Hellenic Air Force and classified as smokers and nonsmokers. The maximum, minimum, and median QT intervals, QT dispersion (QT maximum - QT minimum), the rate-corrected maximum and median QT intervals, the slopes of the QT maximum/RR and QT median/RR regression equations, and the vectorcardiographic markers spatial T amplitude and spatial QRS-T angle were evaluated in the 2 groups. RESULTS: Heart rate was significantly higher (P <.001) in smokers (n =691) compared with nonsmokers (n = 703). QT maximum, QT minimum, and QT median were significantly lower (P <.001), whereas the rate-corrected QT maximum (P =.04) and QT median (P =.06) were marginally higher in smokers than in nonsmokers. The spatial T amplitude was lower (P =.002), whereas the spatial QRS-T angle was higher (P =.01) in smokers compared with nonsmokers. Neither QT dispersion nor the slopes of the QT/RR and the spatial descriptors/RR regression equations differed between smokers and nonsmokers. CONCLUSIONS: Ventricular repolarization is altered in young male cigarette smokers. The differences in the heterogeneity of ventricular repolarization between smokers and nonsmokers are mainly due to heart rate differences between the 2 study groups.
Adult↗
Changes of the T-wave amplitude and angle: an early marker of altered ventricular repolarization in hypertension.
BACKGROUND: The heterogeneity of ventricular repolarization is an important proarrhythmic factor. QT dispersion has been proposed to reflect the inhomogeneity of ventricular repolarization, but a poor reproducibility limits its clinical applicability. Reliable noninvasive methods to quantify abnormalities in ventricular repolarization are still lacking. The T-loop morphology analysis is a novel method aimed at quantifying ventricular repolarization. HYPOTHESIS: To test the ability of the T-loop morphology analysis to discriminate between hypertensive patients and healthy subjects, 105 hypertensive patients (mean age 63.6 +/- 12.3 years) and 110 healthy controls (mean age 49.7 +/- 14.3 years) were evaluated. METHODS: The maximum QT interval (QT maximum), the minimum QT interval (QT minimum), and their difference (QT dispersion) were calculated from a digitally recorded 12-lead electrocardiogram (ECG) in both study groups. X, Y, and Z leads were reconstructed from the 12-lead ECG, and the amplitude of the maximum T vector (T amplitude) and the angle between the maximum T vector and X axis (T angle) were calculated from the projection of the T loop in the frontal plane. RESULTS: T amplitude (p < 0.001), T angle (p = 0.05), and QT dispersion (p = 0.04) were significantly different between hypertensive patients and controls, while QT maximum (p = 0.14) and QT minimum (p = 0.35) did not differ between the groups. T amplitude was the only marker which differed between hypertensive patients without ECG criteria for left ventricular hypertrophy and controls (p = 0.002). CONCLUSIONS: T-loop features and particularly T amplitude are significantly different between hypertensive patients and healthy controls and may serve as early markers of repolarization abnormalities in a hypertensive population.
Action Potentials↗
Implantable defibrillator therapy in Naxos disease.
Naxos disease is a unique form of right ventricular cardiomyopathy with a high prevalence of malignant ventricular arrhythmias, including sudden cardiac death. As a hereditary systemic disease confined to a small island, it has been closely studied over the last 15 years. The implantation of an automatic defibrillator provides an alternative form of antiarrhythmic management to improve life expectancy in these high risk cardiac patients. We present the first two Naxos disease patients with malignant ventricular arrhythmias who had defibrillator implantation.
Arrhythmogenic Right Ventricular Dysplasia↗
Right posterior atrioventricular ring: a location for different types of atrioventricular accessory connections.
We present an unusual case of a 28-year-old female patient with recurrent episodes of tachycardias due to participation of two accessory connections located in the posterior tricuspid annulus. Both connections were of the atrioventricular type, the one with non decremental fast conducting properties at the right posteroseptal area, the other with node-like properties at the posterolateral tricuspid ring. Both pathways were successfully ablated transvenously with radiofrequency energy application at the same session. Implications about a common embryological origin of the two pathways as well as review of the literature for similar cases are presented.
Adult↗
Comparison of different methods for manual P wave duration measurement in 12-lead electrocardiograms.
To determine whether different methods for the manual measurement of P wave duration are mutually consistent, we evaluated the intraobserver and interobserver errors of P wave measurements obtained in three different ways: (1) by cursor on a high resolution computer screen (on screen), (2) by calipers and a magnifying glass (on paper), and (3) by a high resolution digitizing board (on board). The agreement between the methods was assessed in 30 normal subjects and 30 patients with a history of atrial fibrillation. The maximum P wave duration (P maximum), the minimum P wave duration (P minimum), mean P wave duration (P mean), P wave dispersion (P dispersion = P maximum - P minimum), and the standard deviation of the P wave duration in all measured leads (P SD) were calculated from a 12-lead electrocardiogram in each subject. Only P maximum, P mean, and P dispersion were significantly higher in patients than in controls with all three methods. Intraobserver and interobserver relative errors were significantly different among the three methods; the lowest errors were associated with the on-screen measurement. The agreement between the three different methods was acceptable for P maximum, P mean, and P SD and rather poor for P minimum and P dispersion in both groups. The differences of the measurement by different methods did not consistently differ between the two groups. Hence, the on-screen measurements are consistent with other manual methods and provide more stable results. Manual measurement of ECG patterns should be preferably performed with digital ECG recordings displayed on a high resolution computer screen.
Adult↗
Effects of ischemia on QT dispersion during spontaneous anginal episodes.
Myocardial ischemia induced by pacing, angioplasty, or stress results in a significant increase in QT dispersion (QTd = QT maximum - QT minimum). This study investigated the effects of ischemia on QTd and the rate-corrected QTd (QT(c)d) during spontaneous anginal episodes in patients with coronary artery disease (CAD). Ninety-five patients with CAD and typical angina pectoris and 15 control subjects complaining of anginalike symptoms were studied. QTd and QT(c)d were calculated from 12-lead surface electrocardiograms recorded during and after the relief of pain. QTd and QT(c)d were significantly higher during the anginal episode (84+/-31 ms and 98+/-51 ms) compared to the painless conditions (69+/-24 ms and 71+/-24 ms) (P = .003 and P = .001 for QTd and QT(c)d, respectively) only in the 57 CAD patients who had a history of an old previous myocardial infarction. QTd and QT(c)d are significantly increased during spontaneous angina in patients with documented CAD and history of previous myocardial infarction.
Angina Pectoris↗
Coexistence of a left posteroseptal tract with persistent left superior vena cava. Ablation through an anomalous superior vena cava.
A case of a young male with WPW syndrome due to a left posteroseptal tract associated with a persistent left superior vena cava is described. After unsuccessful ablation attempts with a number of different approaches at conventional target sites, the accessory connection was successfully ablated within the coronary sinus. This was achieved only when the ablation catheter was introduced through the persistent left superior vena cava.
Adult↗
Coronary artery disease: changes of blood lymphocyte subsets induced by physical exercise.
To examine the changes in the absolute numbers of blood lymphocyte subsets in patients with coronary artery disease, we studied 26 patients with documented coronary artery disease (group I) and 15 other subjects (group II) with atypical complaints and negative exercise test who served as controls. Blood lymphocyte subsets were determined at rest, immediately and 24 h after a bicycle exercise test. In both groups the absolute number of leukocytes/mm3 and lymphocytes/mm3 was significantly greater immediately after exercise than at rest and returned to baseline values by 24 h post-exercise. The absolute number of B-lymphocytes and CD8+ T-lymphocytes did not change significantly in both groups, while CD3+ and CD4+ T-lymphocytes as well as CD25+ activated T-lymphocytes declined insignificantly immediately after exercise but increased significantly 24 h after exercise in both groups, with a higher increase (P<0.01) in all three variables under study (CD3+, CD4+ and CD25+ T-lymphocytes) in group I in comparison to group II (P<0.05). Our findings showed that changes in lymphocyte subsets induced by physical exercise differ between patients with and without documented coronary artery disease, suggesting that an alteration in immune function may account for these differences.
Aged↗
Reliability of the exercise-induced ST-segment changes to detect restenosis three months after coronary angioplasty: significance of the appearance in other leads.
BACKGROUND: Exercise-induced ST-segment changes 3 months after angioplasty may sometimes show a false-positive result. METHODS: We therefore analyzed the ST changes observed during the exercise tests performed before and 3 months after angioplasty in 118 patients with single-vessel coronary artery disease. RESULTS: Ninety-two (78%) of the 118 patients had ST changes in the same lead before and after angioplasty, whereas the remaining 26 (22%) patients had ST changes in other leads in the postangioplasty test when compared with the preangioplasty exercise test. Restenosis was found in 44 (48%) of the 92 patients with ST changes in the some lead but in only four (15%) of the 26 patients with ST changes in other leads. CONCLUSIONS: Exercise-induced ST-segment changes are not reliable markers of restenosis 3 months after angioplasty. ST-segment changes observed in other leads after angioplasty compared with the preangioplasty exercise test may show a false-positive result.
Adult↗
Reliability of exercise-induced ST segment changes to detect restenosis 3 months after coronary angioplasty: significance of the appearance in other leads.
Exercise-induced ST-segment changes 3 months after angioplasty sometimes may show a false-positive result. We therefore analyzed the ST changes observed during the exercise tests performed before and 3 months after angioplasty in 118 patients with single-vessel coronary artery disease. Ninety-two (78%) of the 118 patients had ST changes in the same lead before and after angioplasty, whereas the remaining 26 (22%) patients had ST changes in other leads in the postangioplasty exercise test when compared with the preangioplasty test. Restenosis was found in 44 (48%) of the 92 patients with ST changes in the same lead but in only 4 (15%) of the 26 patients with ST changes in other leads. We conclude that exercise-induced ST segment changes are not reliable markers of restenosis 3 months after angioplasty. ST segment changes observed in other leads after angioplasty may show a false-positive result when compared with the preangioplasty exercise test.
Adult↗
Hypertrophic cardiomyopathy in Greece: clinical course and outcome.
OBJECTIVE: Evaluation of clinical course and outcome of hypertrophic cardiomyopathy in a representative Greek population. BACKGROUND: Hypertrophic cardiomyopathy is characterized by unexplained left ventricular hypertrophy and varied clinical expression. Recent studies suggest ethnic differences. MATERIALS AND METHODS: One hundred seventy-four consecutive Greek patients (117 male, 57 female, age 47+/-16 years) from 143 different families were assessed at the Department of Cardiology of the University of Athens, Greece, and the State Cardiac Department, Hippokration Hospital, both located in Athens, Greece. To reduce selection bias, referral was based on disease diagnosis irrespective of clinical status or treatment needs. All patients were examined clinically, echocardiographically, and by ECG ambulatory monitoring at 6-month intervals for a period of 74+/-22 months (range, 8 to 108 months). RESULTS: Most patients (n = 156, 89.7%) were in New York Heart Association (NYHA) functional class I or II. The disease was familial (at least one affected first-degree relative) in 81 of the 143 families (56.6%), and in 19 of these (13.3%) there was familial history of sudden cardiac death. At initial examination, intraventricular septal thickness was 17.3+/-4.1 mm and posterior wall thickness was 13.7+/-3.8 mm and a left ventricular outflow gradient >30 mm Hg was present in 58 patients (33.3%). Similar were the findings during the last examination (17.5+/-4.3 mm, 13.5+/-4.4 mm, and 56 (32.2%, respectively, p = not significant). Episodes of nonsustained ventricular tachycardia were noted in 15 patients (8.6%). There were eight deaths during follow-up: four sudden deaths and four from intractable heart failure. Syncope was reported by all patients who died. The annual mortality in this study was 1%. Syncope and NYHA class were the only predictors of outcome. CONCLUSIONS: In this representative Greek patient cohort with hypertrophic cardiomyopathy, the arrhythmogenic substrate was modest and the clinical course benign. Sudden cardiac death was infrequent and syncope, functional class, and ventricular arrhythmias were the only predictors of a poor outcome.
Adolescent↗
The Greek Heart House--a new venture.
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Cardiology↗
Effect of atrial fibrillation on exercise capacity in mitral stenosis.
To determine the preoperative and postoperative effect of atrial fibrillation (AF) on exercise capacity in mitral stenosis, 12 digitalized patients in AF (7 women and 5 men, age 52 +/- 6.1 years) and 10 in sinus rhythm (5 women and 5 men, age 46 +/- 5 years) underwent maximal cardiopulmonary exercise testing according to Weber's protocol and Doppler echocardiographic examination before and at 3 and 6 months after mitral valve replacement. The ratio of right ventricular acceleration to ejection time was used as an estimate of mean pulmonary artery pressure. Preoperative exercise duration (6.8 +/- 1 vs 8 +/- 2 minutes), peak oxygen consumption (9.7 +/- 3 vs 12.3 +/- 3 ml/kg/min), and right ventricular acceleration to ejection time ratio (0.34 +/- 0.07 vs 0.34 +/- 0.08) were not significantly different between patients with AF and those in sinus rhythm. Postoperative improvement in these parameters was lower in patients with AF than in those in sinus rhythm: exercise duration at 3 months, 7.5 +/- 2 vs 11.9 +/- 2 minutes (p < 0.001); at 6 months, 9 +/- 2 vs 12 +/- 2 minutes (p < 0.001); peak oxygen consumption at 3 months, 10.8 +/- 3 vs 17.5 +/- 3 ml/kg/min (p < 0.001); and at 6 months, 11.9 +/- 3 vs 17.8 +/- 3 ml/kg/min (p < 0.001); right ventricular acceleration to ejection time ratio at 3 months, 0.35 +/- 0.08 vs 0.42 +/- 0.05 (p < 0.05); and at 6 months, 0.38 +/- 0.05 vs 0.44 +/- 0.05 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Atrial Fibrillation↗