[Drug therapy and prevention of recurrence of supraventricular tachyarrhythmias].
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Anti-Arrhythmia Agents↗
Biomedical subjects
R Haberl
Publications and source records attributed to R Haberl.
T wave spectral variance: A new method to determine inhomogeneous repolarization by T wave beat-to-beat variability in patients prone to ventricular arrhythmias.
Inhomogeneous repolarization is considered to be associated with increased risk of ventricular arrhythmias, but exact determination of the end of the T wave is difficult, and a single measurement of the QTc interval may be insufficient for risk stratification. A new algorithm was therefore developed to determine the beat-to-beat variability of the T wave in Holter electrocardiographic recordings. This algorithm, termed T Wave Spectral Variance (TWSV) uses the two-dimensional fast Fourier transform to determine the beat-to-beat variability of the T wave in Hotter ECG recordings. The two-dimensional fast Fourier transform was calculated by use of a data matrix with 1,024 consecutive single beats (first dimension) and a 200-ms segment centered on the T wave (second dimension). The power spectra of the 2D-FFT revealed the frequency content of the T wave in the first dimension and the periodicity of these frequencies in cycles per beat in the second dimension. A TWSV index of periodicity was calculated by dividing total spectral energy by spectral energy at 0 cycles per beat. A TWSV index of 0 means a constant T wave from beat to beat; a TWSV index of 1 means a completely irregular T wave. Of the 200 patients investigated, all of whom had had myocardial infarctions, 50 had documented sustained ventricular tachycardia (VT) (<230 beats/min) (group 1), 50 had ventricular fibrillation (VF) (group 2), and 100 were without VT or VF (group 3); 10 normal subjects were also investigated. The visually determined QTc was 442 +/- 62 ms in group 1, 402 +/- 13 ms in group 2, 411 +/- 26 ms in group 3, and 398 +/- 43 ms in normal subjects (differences not significant). The TWSV index was 0.95 +/- 0.14 in group 1, 0.90 +/- 0.16 in group 2, and 0.64 +/- 0.24 in group 3; it showed a highly constant T wave in normal subjects (0.52 +/- 0.23). Differences between patients with VT and VF as against patients without VT or VF were significant (P < .05), whereas no statistical differences between patients with VT and VF could be found. Thus, TWSV, a new method to assess beat-to-beat variability of the T wave, revealed increased heterogeneity of repolarization in patients prone to both VT and VF after myocardial infarction, whereas a single QTc interval measurement showed no significant differences.
Algorithms↗
Analysis of beat-to-beat variability of frequency contents in the electrocardiogram using two-dimensional Fourier transforms.
Late potentials are very small signals (1-20 microV) in the surface ECG with high-frequency components, which are found in patients prone to sustained ventricular tachycardia. Evaluation of these signals requires either very sophisticated recording techniques for single-beat analysis or signal averaging. Signal averaging, however, might disregard information about risk stratification. Therefore, we developed the Single-Beat Spectral Variance (SBSV) based on two-dimensional (2-D) Fourier transform of 80 ms segments of 128 consecutive beats. This approach depicts the beat-to-beat variability of the frequency contents of these ECG segments. An index function enables an objective detection of late potentials. We investigated 35 patients after myocardial infarction and sustained ventricular tachycardia (Group 1), 50 patients after myocardial infarction without ventricular arrhythmias (Group 2) and ten healthy volunteers. SBSV classified 29 of 35 patients (83%) of Group 1 as pathologic, 14 of these 29 patients (48%) exclusively on the basis of marked Wenckebach-like conduction pattern. In Group 2, only five of 50 patients showed abnormal SBSV. In Group 3, we found no pathologic result. Thus, SBSV is a promising new method to investigate late potentials in patients after myocardial infarction. SBSV contains not only the results of frequency analysis after signal averaging, but also evaluates variable ECG components.
Adult↗
[Medicamentous anti-arrhythmia therapy. Is oral adjuvant therapy with electrolytes of value?].
Low serum concentrations of potassium and magnesium are proarrhythmic factors that are well established. Atrial and ventricular fibrillation are facilitated at low serum levels of these electrolytes. Loss of potassium and magnesium might be caused by diuretic therapy, gastrointestinal loss, drugs, and alcohol abuse. However, serum levels are not representative of total body content of potassium and magnesium, hence, adjuvant therapy might be indicated also in the presence of normal serum levels. This is especially true during the initial phase of antiarrhythmic therapy, which is accompanied by proarrhythmia in a significant number of cases. Patients with heart failure should routinely receive adjuvant electrolyte substitution, if renal function is not impaired. In the experimental model magnesium successfully prevented early afterdepolarizations caused by hypokalemia and antiarrhythmic drugs. In the clinical setting high dose magnesium abolished torsade-de-pointes tachycardias caused by antiarrhythmic drugs. Unfortunately, controlled studies are not available for low dose electrolyte therapy adjuvant to antiarrhythmic drug medication.
Anti-Arrhythmia Agents↗
Management of patients with life-threatening ventricular tachyarrhythmias in the defibrillator era: the need to differentiate.
Patients with a history of sustained ventricular tachyarrhythmias form an extremely inhomogeneous group with respect to presenting arrhythmia, underlying cardiac disease, and therefore, risk of dying suddenly. For subgroups such as ventricular tachycardia in the absence of underlying cardiac disease, radiofrequency catheter ablation offers cure. In others, implantation of a cardioverter defibrillator already appears to have gained the therapy of first choice, leaving only a secondary role to antiarrhythmic drugs. It must be emphasized however, that these new therapeutic strategies have their pros and cons like the older, seemingly out-fashioned approaches of noninvasively or invasively guided antiarrhythmic drug therapy or empiric amiodarone treatment. Until the advent of controlled randomized trials comparing the implantable cardioverter defibrillator (ICD) with the best other, usually medical form of treatment, physicians must continue to base their individual therapeutic decisions on circumstantial published and personal experience. In doing so, the recent achievements of catheter ablation and defibrillator implantation have definitely improved patient care, but have not made antiarrhythmic drugs jobless. With all the alternatives at hand, it remains a challenging task to weigh the benefits and risks of the various approaches against each other in an attempt to tailor the antiarrhythmic intervention to the very individual need of the patient.
Amiodarone↗
[A comparison of ultrafast computed tomography, magnetic resonance angiography and selective angiography for the detection of coronary bypass patency].
PURPOSE: Validation of ultrafast-CT and MR-angiography (MRA) in comparison with angiography for detection of early postsurgical arterial and venous coronary artery bypass graft (CABG) patency. METHODS: 21 patients with a total of 55 CABG (34 venous and 21 arterial) were studied with angiography, ultrafast-CT (EBT), and MRA. RESULTS: With EBT, patency of 43/45 angiographically patent CABG could be correctly assessed (sensitivity: 96%). With MRA 26 CABG (17 venous and 9 arterial) were identified as patent (sensitivity: 67%). It was not possible to quantify proximal stenosis of three grafts (> 40%) and to evaluate the distal bypass anastomosis with both EBT and MRA. CONCLUSIONS: Ultrafast-CT is a promising minimal invasive screening method for the evaluation of venous and arterial CABG patency. The diagnostic significance of MRA is remarkably reduced.
Aged↗
[The value of ultrafast computerized tomography in detection of the patency of coronary bypasses].
Bypass graft patency with ultrafast computed tomography (= Electron Beam Tomography, EBT) was examined in 72 bypass grafts (47 saphenous veins, 25 internal mammary arteries) in 30 patients and compared with coronary angiography. Angiography was performed a mean of 4.4 +/- 3.5 months (range 1-13) from the EBT examination. Contrast material (120 ml) was continuously administered via a peripheral vein and 40 axial slices (3 mm slice thickness, 110 ms scan time) without overlap sequences were obtained, ECG triggered with the single slice scanner mode. Imaging of internal mammary artery grafts began at the thoracic inlet, for saphenous vein grafts, at the undersurface of the aorta. Sixty of 63 angiographically patent bypass grafts were determined patent by EBT (sensitivity 95%), 8 bypass grafts could not be detected by EBT, and 9 were angiographically occluded (specificity 89%). Twenty-four of 25 internal mammary artery grafts were patent at EBT and coronary angiography, one was occluded. In 27 of the 30 patients (90%), all of the angiographically patent grafts could be confirmed as open with EBT. Obstructions of 10 grafts could not be visualized with EBT. Graft insertion into native coronary vessels could be visualized in axial slices, although morphologic quantification of graft insertion stenosis (75-90%) in two cases was not possible. Three dimensional reconstruction of the 40 axial slices allowed graft anatomy to be delineated. Visualization of bypass insertion into the native coronary vessel was less successful because of opacification of the left and right ventricle. Electron beam computed tomography is a minimally invasive procedure capable of evaluating the patency of saphenous vein and internal mammary artery grafts. The morphologic quantification of graft obstruction and visualization of the insertion of the bypasses into the native coronary vessels is less successful with present technology and imaging modalities.
Aged↗
[Use of ultra-fast computerized tomography in diagnosis of coronary heart disease].
Ultrafast or electron beam tomography (EBT) permits acquisition of images in 50-100 ms. An artifact-reduced display of heart and vessel structures as well as calcifications can be achieved. Therefore, EBT can be used for the detection and quantification of coronary artery calcification. Thirty-two patients with known coronary artery disease (CAD) were studied by EBT with and without i.v. contrast enhancement and with conventional coronary angiography. Different scoring systems were applied in order to define the basis to compare the data. The results showed a high EBT sensitivity for detection of coronary artery stenosis of up to 94% but low specificity with a maximum of 75%, depending on the scoring system applied. With EBT, differentiation between significant CAD (> 75%) and low-grade CAD (0-75%) showed significant results. The scoring system is not yet completely satisfactory, and with the integration of other screening tests and continuous development of scoring systems, the significance and reliability of this method in evaluation of CAD are expected to increase.
Aged↗
Spectral analysis of the high resolution ECG: current concepts and future directions.
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Action Potentials↗
[The use of digitalis glycosides in atrial fibrillation].
The role of cardiac glycosides for conversion of atrial fibrillation to simus rhythm is controversially discussed. In a prospective study, 45 patients with paroxysmal atrial fibrillation were randomly assigned to one of three treatment groups (of 15 patients each). Group I received oral digoxin, three times 0.125 mg up to twice 0.25 mg daily; group II oral digoxin twice 0.125 mg and quinidine hydrogen sulphate 750-1000 mg daily; group III oral digoxin three times 0.125 mg and flecaimide 200-300 mg daily. During a mean observation period of 11 months, digoxin alone was significantly less effective (p < 0.05) in reducing or suppressing paroxyms of atrial fibrillation than digoxin plus quinidine or flecainide. The use of digoxin remains a mainstay of treatment for rate control in atrial fibrillation. To convert atrial fibrillation to sinus rhythm, however, the addition of a type I or III antiarrhythmic agent is necessary.
Administration, Oral↗
[Blood pressure treatment in the acute phase of a stroke].
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Antihypertensive Agents↗
Diagnosis and results of different treatment regimens in patients with spinal abscesses.
Bacterial abscesses involving the spinal canal are associated with a high morbidity and mortality. Most frequently, these lesions are found in the epidural, rarely in the subdural space. In this report, our clinical material consists of a series of 16 patients treated during the last seven years. The clinical presentation included local neurological signs (back pain, para-/tetraparesis, bladder dysfunction), disturbances of consciousness (ranging from drowsiness to deep coma) and general inflammatory signs (meningism, fever). All patients presented with risk factors (septic foci, chronic diseases, and iatrogenic causes). Laboratory investigations revealed typically pathological blood sedimentation rate, leucocytosis and CSF-pleocytosis. Radiologically, the diagnosis was confirmed by myelography, CT and preferably MRI. The abscesses were located epidurally in 14 and subdurally in 2 cases. The surgical treatment included laminectomy, or multiple flavectomies in extensive lesions. Drainage systems (either simple silicon outflow drains or suction-/irrigation systems) were installed in all cases, as well as antibiotic treatment. Results of treatment: Following an observation period of 0.5-6 years, we found complete recovery in six (38%) cases, six (38%) others were mildly disabled and four (25%) patients died. Focussing on the results of the two different drainage systems, we found a statistically significant superiority of the inflow-/outflow system. Complications included mandatory re-exploration, post-inflammatory hydrocephalus, syringomyelia, spinal instability, surgical treatment of peripheral septic foci and therapy resistant septicaemia. In conclusion, we propose that spinal epi- or subdural abscesses require surgical evacuation, using a suction-/irrigation drainage system, as well as antibiotic and intensive care treatment.
Abscess↗
Temperature-controlled radiofrequency catheter ablation of AV conduction: first clinical experience.
A new technique for catheter ablation of atrioventricular (AV) conduction, using temperature-controlled radiofrequency energy and a bipolar asymmetrical electrode configuration, was applied to 12 patients (mean age, 48 +/- 15 years; range, 18-69 years) with medically refractory atrioventricular nodal reentrant tachycardia (AVNRT) or rapid atrial rhythms. The energy source was a 500 kHz generator with automatic power regulation to a preselected temperature of 80 degrees C. A specially designed 7 F bipolar asymmetric thermo-catheter was used for ablation in all cases. The endpoints of the procedure were: first-degree AV block in patients with AVNRT and third-degree block in patients with atrial fibrillation or flutter. Energy was applied over a range of 1-14 times per patient. After a mean follow-up of 8 +/- 4 months, third- or first-degree AV block persisted in eight patients. In comparison to constant-power radiofrequency ablation, where impedance rises are commonly observed, no impedance rise or coating of the electrode occurred during any of the 97 energy applications in this study. Variable wall contact of the electrode was identified in 20 of 97 applications by a slow temperature rise or a drop in temperature and frequent power adjustments. Thus, monitoring temperature and automatic power regulation may help to reduce the total delivered energy. Temperature control during radiofrequency energy avoids coagulum formation and consequently the associated potential hazards of constant-power application.
Adolescent↗
Randomized crossover comparison of the electrophysiologic and antiarrhythmic efficacy of oral cibenzoline and sotalol for sustained ventricular tachycardia.
We compared the electrophysiologic and clinical effects of oral cibenzoline and sotalol in 12 patients with spontaneous and inducible sustained ventricular tachycardia (VT), using a randomized, open-label, cross-over study. Electrophysiologic studies were performed in the control state, after oral cibenzoline and after oral sotalol, using an incremental dose-titration protocol. Therapy with cibenzoline at the maximum dose level (130-390 mg/day) resulted in complete suppression of VT in 1 of 12 patients (8%). Sotalol (160-320 mg/day) prevented induction of VT in 4 of 12 patients (33%). The effective refractory period (ERP) of the right ventricle was more significantly prolonged with sotalol (p < 0.001) as compared with cibenzoline (p < 0.05). Neither drug prolonged QT duration corrected for frequency (QTc) and cycle length of induced VT, as compared with the control study. Three patients experienced spontaneous VT after cibenzoline administration, and 2 patients experienced incessant VT during programmed electrical stimulation. No patient had a proarrhythmic effect while receiving oral sotalol treatment. Chronic sotalol therapy maintained long-term arrhythmia suppression in all 4 responders at 1-year follow-up. Sotalol appears to have greater efficacy than and a safety profile superior to that of cibenzoline. Drug-related proarrhythmic effects of oral cibenzoline therapy occurred with greater frequency than that associated with other antiarrhythmic drugs. Based on these findings, cibenzoline cannot be recommended for use in patients with VT.
Administration, Oral↗
[Differential therapy of ventricular arrhythmias].
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Anti-Arrhythmia Agents↗
[Recurrent transitory ischemic attacks].
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Aged↗
[Anti-arrhythmic therapy of ventricular arrhythmias. Assessing benefit and risk].
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Anti-Arrhythmia Agents↗
Prognosis of patients with sustained ventricular tachycardia and of survivors of cardiac arrest not inducible by programmed stimulation.
The aim of this study was to analyze the long-term clinical outcome of 60 prospectively studied patients with documented sustained ventricular tachyarrhythmia that was not inducible during baseline programmed ventricular stimulation: 39 with cardiac arrest due to noninfarction ventricular fibrillation (VF) and 21 with mild hemodynamically compromising sustained ventricular tachycardia (VT). Left ventricular ejection fraction was 55 +/- 14% in the VF group and 50 +/- 13% in the VT group (difference not significant). Patients were discharged without conventional antiarrhythmic drugs and received only empirical beta-blocker therapy. During a mean follow-up period of 21 +/- 16 months (mean +/- SD), 10 of 60 patients (17%) died suddenly. The actuarial incidence of sudden death at 1 and 4 years was similar in both groups (VF group, 10 and 20%; VT group, 16 and 16%) (p = 0.48). The actuarial incidence of sudden cardiac death was significantly higher in patients with left ventricular ejection fraction < or = 40% than in those with > 40% (1-year incidence in VF group, 40 vs 0%; VT group, 50 vs 0%) (p = 0.005 and p = 0.01, respectively). Multivariate regression analysis identified left ventricular ejection fraction < or = 40% and previous myocardial infarction as the only independent predictor of sudden cardiac death. The occurrence of frequent ventricular pairs during Holter monitoring was the only independent predictor of sustained VT recurrences. It is concluded that patients with sustained ventricular tachyarrhythmia in whom arrhythmia was non-inducible during baseline ventricular stimulation and not treated with antiarrhythmic therapy have a favorable outcome if left ventricular ejection fraction is high.(ABSTRACT TRUNCATED AT 250 WORDS)
Arrhythmias, Cardiac↗