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Biomedical subjects

R Haberl

Publications and source records attributed to R Haberl.

At least 19 recordsLinked to original sources
PubMed1997

[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↗
PubMed1996

[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↗
PubMed1995

[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↗
PubMed1994

[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↗
PubMed1993

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↗
PubMed1993

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↗
PubMed1993

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↗
PubMed1992

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↗
PubMed1992

A comparison of electrophysiologically guided antiarrhythmic drug therapy with beta-blocker therapy in patients with symptomatic, sustained ventricular tachyarrhythmias.

BACKGROUND: Antiarrhythmic drug therapy guided by invasive electrophysiologic testing is now widely used in patients with symptomatic, sustained ventricular tachyarrhythmias. METHODS: We conducted a prospective, randomized trial in 170 patients to investigate whether this approach would improve long-term outcome. Patients whose arrhythmia was inducible by programmed electrical stimulation were assigned to treatment with electrophysiologically guided drug therapy based on serial testing (61 patients) or with metoprolol (54 patients). Electrophysiologically guided therapy consisted of serial testing of antiarrhythmic agents to identify the first one that rendered the arrhythmia noninducible. The 55 patients whose arrhythmia was noninducible during the initial electrophysiologic test were also treated with metoprolol. RESULTS: During a mean (+/- SD) follow-up period of 23 +/- 17 months, recurrent, nonfatal arrhythmia occurred in 44 patients and sudden death due to cardiac factors in 27. The incidence of symptomatic arrhythmia and sudden death combined was virtually the same in the two groups with inducible arrhythmia after two years of observation (electrophysiologically guided therapy vs. metoprolol therapy, 46 percent vs. 48 percent). The outcome was more favorable in the patients with noninducible arrhythmia at base line (75 percent had neither adverse event) than in those with inducible arrhythmia who were assigned to metoprolol therapy (P = 0.009 by log-rank test). Only 6 of the 29 patients (21 percent) with inducible arrhythmia that became noninducible during drug therapy had recurrent arrhythmia or sudden death, as compared with 21 of the 32 patients (66 percent) with arrhythmia that continued to be inducible (P less than 0.001). A multivariate regression analysis identified continued inducibility of the arrhythmia as an independent predictor of recurrent arrhythmia or sudden death (relative risk, 7.3; 95 percent confidence interval, 2.3 to 23.2; P less than 0.001). CONCLUSIONS: As compared with metoprolol therapy, electrophysiologically guided antiarrhythmic drug therapy did not improve the overall outcome of patients with sustained ventricular tachyarrhythmias. However, effective suppression of inducible arrhythmia by antiarrhythmic drugs was associated with a better outcome than was lack of suppression.

Adrenergic beta-Antagonists↗
PubMed1992

Biophysical parameters of radiofrequency catheter ablation.

Radiofrequency catheter ablation has been shown to be an effective treatment for patients with accessory pathways in Wolff-Parkinson-White syndrome and other supraventricular tachycardias. However, the biophysical parameters used so far in vivo did not correlate to the size of myocardial lesions and provided no information about the myocardial wall contact of the electrode. In this study 104 radiofrequency applications were performed on excised pig myocardium in circulating heparinized pig blood as well as in blood alone, and root mean square (rms) voltage, root mean square current and phase angle were measured using a specially developed device. The calculated effective power and output power differed by only 2-7% when measured at the point of maximum current during coagulation. A drop of current following a rise in impedance led to a phase displacement of more than 80 degrees and thereby to a drop of effective power to 17% of the output power. Hence, apparent output power consists mainly of ineffective power. The time dependent variations of phase angle, impedance and current were found to be useful for distinguishing between the media blood and myocardium. These results show that physical parameters measured during radiofrequency catheter ablation may help to control electrode position in the clinical situation and reduce the number and duration of ineffective energy applications.

Animals↗
PubMed1992

[Anti-arrhythmia and pro-arrhythmia effects of oral cibenzoline therapy in sustained ventricular tachycardia].

The efficacy and safety of the new class-I antiarrhythmic drug cibenzoline was assessed in 12 patients with spontaneous and inducible ventricular tachycardia. Programmed ventricular stimulation, 24-h ambulatory electrocardiogram (ECG), and continuous ECG monitoring were performed without antiarrhythmic drugs and after oral administration of 254 +/- 80 mg of the substance. Oral cibenzoline suppressed the induction of tachycardia in only one patient. Induction of tachycardia was more difficult in two patients, unchanged in four patients, and easier in two patients. Cycle length of induced tachycardia and QT-interval corrected for frequency were not changed significantly; effective refractory period of the right ventricle was prolonged. Twenty-four hours of ambulatory monitoring during cibenzoline treatment (n = 9) showed no significant increase in the frequency of ventricular premature complexes. However, spontaneous sustained ventricular tachycardia developed in three patients after initiation of cibenzoline treatment. In two patients, termination of induced ventricular tachycardia was significantly more difficult under cibenzoline; several DC-shocks were required to terminate the tachycardia. Thus, the use of oral cibenzoline in patients with sustained spontaneous and inducible ventricular tachycardias showed a low antiarrhythmic efficacy at programmed stimulation and a high incidence of spontaneous ventricular tachycardia.

Adult↗
PubMed1991

[Late potentials as risk parameters after heart infarct].

Sustained ventricular tachycardias and sudden death can pose a threat to post-infarction patients. Patients at risk cannot be identified with adequate reliability with Holter monitoring or programmed ventricular stimulation. Late potentials arise as a result of delayed excitation in the marginal region of an infarct and reflect structural myocardial changes that represent the precondition for circus movement. Special methods have been developed to detect these potentials, which on the surface of the body are very small (1-10 microV). These potentials can be found in 70-80% of post-infarction patients with sustained ventricular tachycardias or fibrillation, but are rarely seen in MI patients with no arrhythmia. Late potential analysis represents a promising method of assessing the arrhythmogenic risk of post-infarction patients.

Electrocardiography↗