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Biomedical subjects

B Hauer

Publications and source records attributed to B Hauer.

At least 55 records · Page 3Linked to original sources
PubMed1998

Comparison of metoprolol and sotalol in preventing ventricular tachyarrhythmias after the implantation of a cardioverter/defibrillator.

The purpose of this prospective study was to evaluate, on an intention-to-treat basis, the efficacy of d,l-sotalol and metoprolol with regards to the recurrence of arrhythmic events after implantable cardioverter defibrillator (ICD) implantation. After ICD implantation, 70 patients were randomly assigned to treatment with either metoprolol (mean dosage 104+/-37 mg/day in 35 patients) or d,l-sotalol (mean dosage 242+/-109 mg/day in 35 patients). During follow up ventricular tachycardia (VT), fast VT, and ventricular fibrillation (VF) episodes were calculated. Metoprolol treatment led to a marked reduction in the recurrence of arrhythmic events. Actuarial rates for absence of VT recurrence at 1 and 2 years were significantly higher in the metoprolol group compared with the d,l-sotalol group (83% and 80% vs 57% and 51%, respectively, p=0.016). The actuarial rates for absence of fast VT or VF were 80% in the metoprolol group compared with 46% in the d,l-sotalol group (p=0.002). During a follow up of 26+/-16 months, there were 3 deaths in the metoprolol group compared with 6 deaths in the d,l-sotalol group. Actuarial rates of overall survival were not significantly different in the 2 groups (91% vs 83%, p=0.287). In this prospective, randomized, controlled study the recurrence rate of ventricular tachyarrhythmias in patients treated with metoprolol was lower than in patients treated by d,l-sotolol.

Adolescent↗
PubMed1998

Risk of thromboembolic events in patients with atrial flutter.

Based on multiple studies, clear, guided anticoagulation therapy is recommended for patients with atrial fibrillation. The value of anticoagulation therapy in patients with atrial flutter, however, is less well established. Little is known about the incidence of thromboembolism in patients with atrial flutter. We evaluated the risk of thromboembolism in 191 consecutive unselected patients referred for treatment of atrial flutter. A history of embolic events was noted in 11 patients. Acute embolism (<48 hours) occurred in 4 patients (3 after direct current cardioversion, 1 after catheter ablation). During follow-up of 26+/-18 months, 9 patients experienced thromboembolic events. During the follow-up, the overall embolic event rate (including acute embolism and thromboembolic events during follow-up) was 7 % in this patient population. Risk indicators for an embolic event in an univariate analysis were organic heart disease (p = 0.037), depressed left ventricular function (p = 0.02), history of systemic hypertension (p = 0.004), and diabetes mellitus (p = 0.0038). Using multivariate analysis, a history of hypertension was the only independent predictor for elevated embolic risk in this patient population (odds ratio = 6.5; 95% confidence intervals 1.5 to 45). Thus, the thromboembolic risk is higher than previously recognized for patients with atrial flutter. Anticoagulation therapy may decrease this risk.

Aged↗
PubMed1998

[Incidence of atrial fibrillation in relation to atrial catheter site in two-chamber pacemakers].

INTRODUCTION: This study evaluated the impact of the atrial lead implantation site on the subsequent development of atrial arrhythmias. METHOD: Dual chamber pacemakers were implanted in 109 consecutive patients. The indication was AV-block in 51 patients, sick sinus syndrome in 58 patients. No patient had chronic atrial fibrillation, but 12 patients (11%) had paroxysmal atrial fibrillation before implantation. Patients were classified according to the atrial lead implantation site: right atrial appendage and right atrial free wall. RESULTS: Preimplant episodes of atrial fibrillation were similar in patients with lead implantation at the free wall and with implantation in the right atrial appendix (13% vs 7.5%, P=0.53). During a mean follow-up of 24+/-13 months, new paroxysmal atrial fibrillation occurred in 5% after lead implantation in the appendix vs 28% of patients after implantation at the right atrial free wall (P = 0.004). CONCLUSION: The development of atrial arrhythmias in dual chamber pacing is influenced by the implantation site of the atrial lead. The frequency of atrial arrhythmias during follow-up is higher after atrial lead implantation at the right lateral wall than in the appendix.

Adult↗
PubMed1998

Is the atrial high rate episode diagnostic feature reliable in detecting paroxysmal episodes of atrial tachyarrhythmias?

The atrial high rate episode diagnostic in the Thera pacemaker reports frequency, duration, and date/time of atrial tachyarrhythmias according to programmed criteria. The aim of the study was to validate the atrial high rate episode diagnostic feature. Episodes of atrial fibrillation recorded by Holter monitoring were compared to episodes detected by the pacemaker. Forty five ambulatory (Holter) recordings were used for evaluation. Thirty of 45 ambulatory (Holter) recordings showed sinus rhythm. On 4 of these 30 ambulatory (Holter) recordings, the Thera detected 12 episodes of atrial tachyarrhythmias as false-positives (sinus rhythm was detected as atrial tachyarrhythmia). The main reason was far-field R and T was oversensing. On 15 of 45 ambulatory (Holter) recordings, 125 episodes of atrial tachyarrhythmias were recorded. Ninety-three of these events also were detected by the pacemaker, while for 32 events the Thera reported sinus rhythm. The main reason was that the episodes were of too short duration. Therefore, the Thera (programmed with detection rate 160 beats/min, detection beats 40, termination beats 10) was unable to detect atrial tachycardias. Software simulation of the diagnostic algorithm under several programming settings using the digitized Holter files demonstrated highly reliable detection of atrial tachyarrhythmias (sensitivity 98%, specificity 100%) when programmed as follows: detection rate 220 beats/min, detection beats 10, termination beats 20. It can be concluded that Thera's high rate episode monitor is a reliable tool for detection of atrial tachyarrhythmias, if programmed as recommended.

Aged↗
PubMed1998

Unexpected complete AV block following transcatheter ablation of a left posteroseptal accessory pathway.

Radiofrequency catheter ablation is the procedure of choice for the nonpharmacological treatment of AV connections that are responsible for debilitating tachycardia. This article describes a patient with a manifest left posteroseptal accessory pathway and recurrent syncopes in whom a transient complete AV block occurred after transcatheter radiofrequency ablation of the left posteroseptal pathway. Three electrical abnormalities were present in this patient: AV infra-Hisian block, a left posteroseptal accessory pathway, and an AV nodal reentry tachycardia. This case report reminds you that one should be prepared for all fall backs during catheter ablation.

Atrioventricular Node↗
PubMed1998

Stereo- and regioselective hydroxylation of alpha-ionone by Streptomyces strains.

A total of 215 Streptomyces strains were screened for their capacity to regio- and stereoselectively hydroxylate beta- and/or alpha-ionone to the respective 3-hydroxy derivatives. With beta-ionone as the substrate, 15 strains showed little conversion to 4-hydroxy- and none showed conversion to the 3-hydroxy product as desired. Among these 15 Streptomyces strains, S. fradiae Tü 27, S. arenae Tü 495, S. griseus ATCC 13273, S. violaceoniger Tü 38, and S. antibioticus Tü 4 and Tü 46 converted alpha-ionone to 3-hydroxy-alpha-ionone with significantly higher hydroxylation activity compared to that of beta-ionone. Hydroxylation of racemic alpha-ionone [(6R)-(-)/(6S)-(+)] resulted in the exclusive formation of only the two enantiomers (3R,6R)- and (3S, 6S)-hydroxy-alpha-ionone. Thus, the enzymatic hydroxylation of alpha-ionone by the Streptomyces strains tested proceeds with both high regio- and stereoselectivity.

Hydroxylation↗
PubMed1998

Importance of preimplantation procedures in candidates for an implantable atrial defibrillator.

INTRODUCTION: Due to the limited efficacy of antiarrhythmic drugs for the treatment of atrial fibrillation, several nonpharmacologic therapeutic options have been developed. One of these options is an implantable atrial defibrillator for patients with severe symptoms and infrequent drug-refractory episodes of atrial fibrillation. The purposes of this study were: (1) to evaluate how many patients with atrial fibrillation are possible candidates for an implantable atrial defibrillator; and (2) to report the results and findings of preimplantation testing in a single center. METHODS AND RESULTS: From our atrial fibrillation outpatient clinic, we evaluated the number of possible candidates for an atrial defibrillator using the following criteria: (1) recurrent persistent atrial fibrillation; (2) long-lasting but infrequent episodes; (3) refractory to antiarrhythmic drugs; (4) capability of maintaining normal sinus rhythm; and (5) no factors increasing proarrhythmic risk. In those patients eligible for an atrial defibrillator, a separate preimplantation test was performed to evaluate atrial defibrillation limits and patient acceptance. Thirty-one of 196 patients were possible candidates for an atrial defibrillator. Fourteen of these 31 patients agreed to participate in the METRIX clinical study phase I on atrial defibrillators. Six of these patients met implantation criteria; two patients refused permanent implantation because of intolerable pain. Implantation was performed in four patients; however, one patient could not be cardioverted intraoperatively despite a successful preimplantation test. CONCLUSION: About 16% of selected patients with atrial fibrillation are possible candidates for an atrial defibrillator. However, successful preimplantation testing does not exclude implantation failure.

Aged↗
PubMed1997

[Catheter ablation in cardiac arrhythmia. Interventional therapy of symptomatic and threatening arrhythmias of the heart].

Catheter ablation is a curative intervention for the treatment of supraventricular, but also ventricular, tachycardias that has proved both safe and effective. In patients with supraventricular tachycardias in underlying WPW syndrome or nodal tachycardia and appreciable symptoms, catheter ablation can be considered the treatment of choice. But many patients with monomorphic ventricular extrasystole that is difficult to control medically experience considerable subjective impairment in their daily life. It is possible that in such patients, too, catheter ablation may, sometime in the future, be used to cure their condition. However, long-term results must first be awaited.

Aged↗
PubMed1997

An improved colony-PCR method for filamentous fungi for amplification of PCR-fragments of several kilobases.

A method was developed to perform PCR directly on mycelial pellets or colonies treated with NOVOzym 234. The method allows rapid screening of large numbers of transformants of both sporulating and non-sporulating fungi for the presence of (co)transforming plasmid copies or for specific genetic modifications such as gene disruption and site specific integration. PCR fragments of at least 3.2 kb can be obtained. Using this method the identification of specific disruption mutants from Aspergillus niger and Beauveria bassiana was carried out.

Aspergillus niger↗
PubMed1997

[Problems in carrying out baroreflex sensitivity measurements in clinical routine practice: practicability and complications].

Measurement of baroreflex sensitivity is a new method to identify patients after myocardial infarction with a high risk for sudden cardiac death, ventricular tachycardia or ventricular fibrillation. In this retrospective study the baroreflex sensitivity was obtained noninvasively by measuring the systolic blood pressure blood pressure with a FINAPRES-device and correlating this with the R-R intervals of the ECG after raising blood pressure with an intravenous dose of Norfenefrin-hydrochloride (Novadral). According to other investigators a correlation of > 0.7 with a significance of p < 0.05 was recommended for evaluable results with a baroreflex sensitivity < 3 ms/mm Hg being judged as decreased. We investigated 302 patients (mean age 59 +/- 17 years, 224 males, 78 females). 75% of the investigations showed acceptable results. In 77 cases (25%) reasonable results could not be achieved. We found premature ventricular beats to be responsible in 18 investigations (6% of all investigations). 41 (13.1%) of all investigations were not evaluable because of bad correlation for unknown reason. When we looked closely at these nonevaluable results, we found a significantly higher number of patients with impaired left ventricular ejection fraction (< 40%), diabetes or inducible sustained ventricular tachyarrhythmia in the electrophysiologic study in this group. During all investigations no severe side effects were observed. We conclude that the noninvasive measuring of the baroreflex sensitivity is a save method and leads to reasonable results in 75% of the investigations. In 13.1% it is not possible for unknown reason to achieve sufficiently correlating values. These measurements cannot be evaluated from nowadays' standards and have to be further investigated as they may indicate a population at high risk.

Adult↗
PubMed1997

[High frequency catheter ablation as therapy of symptomatic ventricular extrasystole].

Ventricular ectopic activity is commonly encountered in clinical practice. Usually it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be highly symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacological therapy are the mainstays of treatment. This study assesses the useful role of catheter ablation in eliminating drug refractory monomorphic ventricular ectopic beats in severely symptomatic patients. Eight patients were included, five patients had no heart disease and in three patients a structural heart disease was present (coronary artery disease in 1, hypertensive heart disease in 1, mitral valve prolaps in 1). The ejection fraction was higher than 40% in all patients (mean EF 56 +/- 14%). Mean number of ventricular ectopic activity was 29,295 +/- 10,650 VPB/24 h (1209 +/- 457 VPB/h) before ablation. No other spontaneous or induced arrhythmias were documented. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both. The ectopic focus was located in the right ventricular outflow tract in five patients and in the left ventricle in three patients (posteroseptal 2, anterolateral 1). Frequent ventricular ectopic beats were successfully eliminated by catheter ablation in all patients. Early recurrence occurred in one patient after 10 min and 30 min after the procedure. In another patient a recurrence occurred 6 days after the procedure. In a second session he was successfully ablated and remained free of recurrence since 2 months. After ablation the mean number of ventricular premature beats was 211 +/- 159 VPB/24 h (9 +/- 7 VPB/h). The mean number of radiofrequency applications was 8 +/- 7 (range 2-22). Mean radiation time was 12 +/- 8 min. No complications were observed. During a mean follow-up of 6 months there were no further recurrences in the remaining six patients. Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug resistant monomorphic ventricular ectopic activity.

Adult↗
PubMed1997

2-oxo-1,2-dihydroquinoline 8-monooxygenase: phylogenetic relationship to other multicomponent nonheme iron oxygenases.

2-Oxo-1,2-dihydroquinoline 8-monooxygenase, an enzyme involved in quinoline degradation by Pseudomonas putida 86, had been identified as a class IB two-component nonheme iron oxygenase based on its biochemical and biophysical properties (B. Rosche, B. Tshisuaka, S. Fetzner, and F. Lingens, J. Biol. Chem. 270:17836-17842, 1995). The genes oxoR and oxoO, encoding the reductase and the oxygenase components of the enzyme, were sequenced and analyzed. oxoR was localized approximately 15 kb downstream of oxoO. Expression of both genes was detected in a recombinant Pseudomonas strain. In the deduced amino acid sequence of the NADH:(acceptor) reductase component (OxoR, 342 amino acids), putative binding sites for a chloroplast-type [2Fe-2S] center, for flavin adenine dinucleotide, and for NAD were identified. The arrangement of these cofactor binding sites is conserved in all known class IB reductases. A dendrogram of reductases confirmed the similarity of OxoR to other class IB reductases. The oxygenase component (OxoO, 446 amino acids) harbors the conserved amino acid motifs proposed to bind the Rieske-type [2Fe-2S] cluster and the mononuclear iron. In contrast to known class IB oxygenase components, which are composed of differing subunits, OxoO is a homomultimer, which is typical for class IA oxygenases. Sequence comparison of oxygenases indeed revealed that OxoO is more related to class IA than to class IB oxygenases. Thus, 2-oxo-1,2-dihydroquinoline 8-monooxygenase consists of a class IB-like reductase and a class IA-like oxygenase. These results support the hypothesis that multicomponent enzymes may be composed of modular elements having different phylogenetic origins.

Amino Acid Sequence↗
PubMed1996

Increased mutagenesis mediated by cloned plasmid CAM-OCT genes: potential for expanding substrate ranges of Pseudomonas spp.

Twenty-five kilobases of Pseudomonas plasmid CAM-OCT DNA encoding a DNA repair gene(s) was cloned into the broad-host-range vector pVK100. The presence of the cloned genes increased the isolation frequency of Pseudomonas putida derivatives capable of using ethyl lactate or 3-methyl-3-buten-1-ol as their carbon source 15- and 8-fold, respectively, after UV irradiation. Ethyl lactate-utilizing strains expressed a novel intracellular hydrolase.

Alkanes↗
PubMed1996

[Renaissance of beta blocker therapy in myocardial infarct].

Beta-adrenergic blocking drugs have been evaluated for the treatment of arrhythmias and for the prevention of sudden cardia death, particularly in post-myocardial infarction patients. Betablockers have been demonstrated to reduce mortality, reinfarction, ventricular fibrillation and cardiac rupture in acute infarction. Therefore, in patients with suspected myocardial infarction and without contraindications, treatment with betablockers should be initiated early and continued for at least 2 years. Side-effects are mild and occur in approximately 10% of patients. Patients who have contraindications for betablockers use early in myocardial infarction should be reevaluated before discharge from the hospital and considered for such therapy. Because betablockers prevent some of the adverse arrhythmogenic mechanisms seen in chronic heart failure, it may be reasonable to expect that these drugs could have a role in preventing sudden cardiac death in these patients. Analysis of some of the betablocker post-infarction trials indicate that betablockers reduced the risk of sudden death in patients with heart failure at baseline. Some studies demonstrated also the symptomatic improvement following therapy with betablockers in patients with heart failure. But the currently available data are too limited to provide conclusive information.

Adrenergic beta-Antagonists↗