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B Lüderitz

Publications and source records attributed to B Lüderitz.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Radiofrequency ablation in ventricular extrasystole of the right ventricular outflow tract].

The series of five patients with symptomatic isolated right ventricular outflow tract ectopy and no structural heart disease which were successfully treated with radiofrequency ablation of the ectopic focus are reported in order to discuss radio-frequency ablation as an alternative treatment in patients with right ventricular outflow tract ectopy without ventricular tachycardia.

Cardiac Complexes, Premature↗
PubMed1997

[Increased apoptosis and necrosis of coronary plaques in unstable angina].

In acute coronary syndromes, arteriosclerotic plaques are characterized by inflammation and decreased smooth muscle cell density. The underlying pathogenic processes remain unclear. Among others, increased programmed cell death (apoptosis) is postulated. Coronary atherectomy specimens from 26 patients with unstable angina (group 1) and from 24 patients with stable angina (group 2) were examined, using immunohistochemistry (TUNEL test to detect fragmented DNA) and transmission electron microscopy. The objectives of the present study were to evaluate plaque group differences in the cellular composition, to detect and quantify cell death, and to differentiate between apoptosis and necrosis. Group 1 lesions contained more macrophages and lymphocytes as well as significantly (p = 0.01) less smooth muscle cells compared with group 2 lesions, whereas both revealed a comparable cell density. All plaques showed signals for fragmented DNA. TUNEL-positive cells were seen more frequently in lesions with unstable angina (p = 0.04). Ultrastructural analysis revealed signs of programmed cell death, such as nuclear alterations, cellular condensation due to lost adhesion, and apoptotic bodies. Importantly, group I lesions comprised significantly more apoptotic SMCs and apoptotic macrophages compared with group 2 lesions (28% vs. 16%; p = 0.02). Also, cellular necroses were found to be increased in lesions with unstable angina (18% vs. 8%; p = 0.02). The density of macrophages showed a positive correlation to the incidence of cellular necroses in group 1 lesions (r = 0.44; p = 0.02), but not in group 2 lesions. In both plaque groups, this determinant was independent from cellular apoptosis, also at high levels as found with unstable angina. The present study on coronary atherectomy specimens with unstable angina reveals intimal macrophage infiltration and the density of apoptotic as well as necrotic intimal cells to be increased, whereas the content of intact SMCs was reduced. Increased, macrophage-independent apoptosis strongly points to the presence of one or several pro-apoptotic intimal factor(s) predisposing to plaque rupture. Implications of our findings may be directed to identify this (these) factor(s) and to modulate endogenous apoptotic activity with the ultimate goal to raise regional smooth muscle cell density.

Angina, Unstable↗
PubMed1997

Left atrial chamber and appendage function after internal atrial defibrillation: a prospective and serial transesophageal echocardiographic study.

OBJECTIVES: The purpose of this prospective study was to assess left atrial chamber and appendage function after internal atrial defibrillation of atrial fibrillation and to evaluate the time course of recovery. BACKGROUND: External cardioversion of atrial fibrillation may result in left atrial appendage dysfunction ("stunning") and may promote thrombus formation. In contrast to external cardioversion, internal atrial defibrillation utilizes lower energies; however, it is unknown whether the use of lower energies may avoid stunning of the left atrial appendage. METHODS: Transesophageal and transthoracic echocardiography were performed in 20 patients 24 h before and 1 and 7 days after internal atrial defibrillation to assess both left atrial chamber and appendage function. Transthoracic echocardiography was again performed 28 days after internal atrial defibrillation to assess left atrial function. The incidence and degree of spontaneous echo contrast accumulation (range 1+ to 4+) was noted, and peak emptying velocities of the left atrial appendage were measured before and after internal atrial defibrillation. To determine left atrial mechanical function, peak A wave velocities were obtained from transmitral flow velocity profiles. RESULTS: Sinus rhythm was restored in all patients. The mean +/- SD peak A wave velocities increased gradually after cardioversion, from 0.47 +/- 0.16 m/s at 24 h to 0.61 +/- 0.13 m/s after 7 days (p < 0.05) and 0.63 +/- 0.13 m/s after 4 weeks. Peak emptying velocities of the left atrial appendage were 0.37 +/- 0.16 m/s before internal atrial defibrillation, decreased significantly after internal atrial defibrillation to 0.23 +/- 0.1 m/s at 24 h (p < 0.01) and then recovered to 0.49 +/- 0.23 m/s (p < 0.01) after 7 days. The corresponding values for the degree of spontaneous echo contrast were 1.2 +/- 1.2 before internal atrial defibrillation versus 2.0 +/- 1.0 (p < 0.01) and 1.1 +/- 1.3 (p < 0.01) 1 and 7 days after cardioversion, respectively. One patient developed a new thrombus in the left atrial appendage, and another had a thromboembolic event after internal atrial defibrillation. CONCLUSIONS: Internal atrial defibrillation causes depressed left atrial chamber and appendage function and may result in the subacute accumulation of spontaneous echo contrast and development of new thrombi after cardioversion. These findings have important clinical implications for anticoagulation therapy before and after low energy internal atrial defibrillation in patients with atrial fibrillation.

Anticoagulants↗
PubMed1997

Torsade-de-pointes.

Explore the source record for details and available documents.

Electrocardiography↗
PubMed1997

Dose and rate-dependent effects of adenosine on atrial action potential duration in humans.

Adenosine provokes atrial fibrillation (AF) in some patients with paroxysmal supraventricular tachycardia (PSVT). Which patients are more susceptible to develop atrial fibrillation after the administration of adenosine to terminate PSVT is unknown. We prospectively measured atrial action potential duration (APD) at incremental doses of 3, 6, and 12 mg of adenosine at paced cycle lengths (CLs) of 600, 500, and 400 ms in 25 patients. Bolus injection of adenosine decreased APD at 90% repolarization in a dose- and rate-dependent manner. During paced CLs of 600, 500, and 400 ms, decreases of 8%, 13%, and 19% (p < 0.05), respectively, were found after bolus administration of 3 mg of adenosine. After 6 mg of adenosine, the APD shortened by 12%, 19%, (p < 0.05), and 27% (p < 0.01), respectively. After 12 mg of adenosine, the APD shortened by 15%, 27% (p < 0.05), and 38% (p < 0.01), respectively. Transient AF occurred in 4 of 25 (16%) patients, all during paced CLs of 400 ms, and after adenosine 6 mg in one patient and 12 mg in three patients. Adenosine shortens atrial action potential duration in a dose- and rate-dependent manner. Whether patients with faster rates during PSVT and those given higher doses of adenosine are more prone to develop atrial fibrillation remains to be determined.

Action Potentials↗
PubMed1997

Radiofrequency catheter ablation of atrial flutter that elicits inappropriate implantable cardioverter defibrillator discharge.

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.

Atrial Flutter↗
PubMed1997

Oxygen uptake kinetics during low intensity exercise: relevance for rate adaptive pacemaker programming.

OBJECTIVE: To establish a normal database for oxygen uptake (VO2) kinetics during low intensity treadmill exercise (LITE) testing, to be used as a guideline for programming rate adaptive pacemakers, and to determine its relation to VO2 at anaerobic threshold and peak exercise. DESIGN: VO2 kinetics during LITE were compared with VO2 at anaerobic threshold and at peak exercise. SETTING: LITE testing is applicable during ambulatory or hospital care and can even be performed by patients with reduced cardiac capacity. PATIENTS: 60 healthy subjects (23 women, 51.6 (SD 20.4) years; 37 men, 42.2 (16.2) years). INTERVENTIONS: Treadmill exercise testing with "breath by breath" gas exchange monitoring using the LITE protocol for steady state, submaximal exercise, and the ramping incremental treadmill exercise (RITE) protocol for peak exercise. MAIN OUTCOME MEASURES: Mean response time of VO2, mean oxygen deficit, and VO2 at anaerobic threshold (VO2-AT) and at peak exercise (VO2-peak) were determined. RESULTS: (1) LITE protocol: mean response time of VO2 = 35.1 (9.9) s; oxygen deficit = 418.3 (47.9) ml; oxygen deficit/VO2 time index = 54.7 (7.4). (2) RITE protocol: VO2-AT = 22.1 (5.7) ml/kg/min; heart rate at anaerobic threshold = 120.1 (3.6) beats/min; VO2-peak = 37.6 (10.7) ml/kg/min; peak heart rate = 167.8 (19.3) beats/min. The mean response time and oxygen deficit/VO2 time index were significantly correlated to VO2-peak and VO2-AT (P < 0.01). CONCLUSIONS: VO2 kinetics calculated in healthy controls may serve as a control database for assessing the rate response programming of pacemakers and its influence on VO2 during LITE. Because aerobic capacity below the anaerobic threshold is more likely to represent activity in daily life and the kinetics of VO2 are significantly related to VO2 at anaerobic threshold and peak exercise, LITE may provide a clinically useful correlate to peak exercise testing.

Adult↗
PubMed1997

Left atrial appendage function in patients with atrial flutter.

OBJECTIVE: To determine whether echocardiographic markers thromboembolic risk differ between patients with pure atrial flutter and patients with atrial flutter and intermittent atrial fibrillation. DESIGN: Patients with atrial flutter were followed up prospectively for 12 months to identify intermittent atrial fibrillation. After the follow up period, transthoracic and multiplane transoesophageal echocardiography were performed to assess left atrial chamber and appendage size, peak emptying velocities, and emptying fraction of the left atrial appendage. The presence of spontaneous echo contrast was also determined. SETTING: Tertiary cardiac care centre. PATIENTS: 20 consecutive patients with atrial flutter; 11 healthy subjects in sinus rhythm served as controls. RESULTS: Intermittent atrial fibrillation was documented in 11 patients by Holter monitoring or surface ECG; atrial fibrillation was not found in the other nine patients. Compared with the patients with pure atrial flutter, patients with atrial flutter and intermittent atrial fibrillation had larger left atrial chamber (mean (SD) 4.5 (0.6) v 3.8 (0.5) cm; 95% confidence interval 0.2 to 1.2; P = 0.01) and appendage areas (6.7 (2.2) v 4.8 (4.9) cm; 95% CI 0.4 to 3.5; P = 0.02), lower left atrial appendage emptying fractions (33 (11)% v 52 (11)%; 95% CI 8 to 29; P = 0.008), and also lower left atrial appendage emptying velocities (0.44 (0.21) v 0.79 (0.27) m/s; 95% CI 0.13 to 0.56; P = 0.005). In addition, a higher incidence of spontaneous echo contrast (11% v 36%) was observed in patients with atrial flutter and intermittent atrial fibrillation. CONCLUSIONS: Left atrial appendage function is depressed and spontaneous echo contrast more frequent in patients with atrial flutter and intermittent atrial fibrillation, as opposed to patients with pure atrial flutter. These data support the concept that patients with atrial flutter and intermittent atrial fibrillation have an increased risk of thromboembolic events and should therefore receive adequate anticoagulant treatment.

Aged↗
PubMed1997

Predictive diagnostic value of clinical assessment and nonlaboratory monitoring system recordings in patients with symptoms suggestive of obstructive sleep apnea syndrome.

UNLABELLED: Obstructive sleep apnea syndrome (OSA) is of increasing importance because of its high prevalence and danger of morbidity to untreated patients. Diagnostic procedures need simplification. We evaluated the qualitative value of a stepwise diagnostic approach using clinical assessment and a home-based screening device according to current recommendations. METHODS: We investigated 114 patients with symptoms suggestive of obstructive sleep apnea syndrome by means of their clinical features, questionnaire responses, four-channel nonlaboratory monitoring (NLM) and full polysomnography. Operative indices in the diagnosis of OSA were calculated. RESULTS: A significant correlation (r = 0.7: p < 0.0001) was found between the oxygen desaturation index (ODI) and the respiratory disturbance index (RDI). The calculation of the difference between ODI by NLM and RDI by polysomnography showed a lack of agreement. Home-based monitoring revealed a high sensitivity (94%) but a low specificity (41%) in diagnosing OSA. However, a combination of clinical features, questionnaires and pulse oximetry achieved a specificity of 92%. CONCLUSION: Home-based monitoring provides reasonable negative predictive values in the diagnosis of OSA syndrome in symptomatic patients. It therefore qualifies as a screening method. Combined with clinical features and questionnaires it provides high positive predictive values and may therefore prove useful in simplifying diagnostic procedures.

Aged↗
PubMed1997

[Heart rate variability in patients with sleep associated breathing disorders].

The increased mortality among patients with obstructive sleep apnoea syndrome has been explained in part by the increased incidence of pulmonary hypertension and coronary artery disease (CAD). A decreased heart rate variability has been shown to be associated with an increased mortality as well. We therefore screened 53 patients for sleep-related breathing disorders (SRBD) and heart rate variability (HRV) during the sleeping period. Standard time domain parameters were compared in a univariate multifactorial model for patients with an oxygen desaturation index (ODI) of more or less than 5 including the factors CAD, diabetes and beta-blocker use. The percentage of differences between RR-intervals that differ more than 50 ms (pNN > 50: 9.0 +/- 11.1% vs 19.2 +/- 22.2%; p < 0.05) as well as the root mean square of these differences (rMSSD: 38.0 +/- 29.0 msec vs 59.2 +/- 51.5 msec; p < 0.05) were significantly decreased in patients with SRBD. These results favour HRV for inclusion in future risk stratification models in patients with sleep-related breathing disorders.

Adult↗
PubMed1996

Epicardial neodymium. YAG laser photocoagulation of ventricular tachycardia without ventriculotomy in patients after myocardial infarction.

BACKGROUND: Surgical ablation of ventricular tachycardia (VT) after myocardial infarction has been reported by different endocardial approaches. The ventriculotomy may increase mortality of the procedure. METHODS AND RESULTS: We report on nine patients who suffered from recurrent VT in the late post-myocardial infarction period. Significant stenoses were detected in all patients. The mean left ventricular ejection fraction was 43.1 +/- 8.3%. Left ventricular scar (n = 9) was seen. The mean NYHA class was 2.2 +/- 0.4. Sustained VT (mean cycle length, 293 +/- 52 ms) occurred spontaneously (n = 9) and could be induced reproducibly. Catheter mapping detected a prematurity of -42 +/- 13 ms in six patients. Clinical VT was inducible during surgery in seven patients. Middiastolic potentials were detected from the epicardial surface (n = 3), and premature potentials were found (n = 8 with prematurity of -108 +/- 46 ms). Application of neodymium/yttrium/argon/ garnet (Nd:YAG) laser energy to early epicardial activation terminated the arrhythmia (n = 7). Ventriculotomy was not performed. Seven patients have been free of VT for a mean follow-up period of 17 +/- 11 months; one patient relapsed and was treated with an implantable cardioverter-defibrillator, as was a second patient with inducible VT after surgery. CONCLUSIONS: Surgical Nd:YAG laser photocoagulation of VT on the epicardial surface of the heart in post-myocardial infarction patients without ventriculotomy is safe and has a high success rate. At the present time, this method is recommended in patients with sustained and tolerated VT who need bypass surgery. This is the first report on epicardial laser ablation of VT in post-myocardial infarction VT.

Adult↗
PubMed1996

Quality of life and driving in recipients of the implantable cardioverter-defibrillator.

UNLABELLED: The efficacy of a treatment is primarily based on objective criteria, such as mortality and morbidity. Besides these criteria, the interest in measuring quality of life (QOL) in relation to health care has increased in recent years. Although the concept of patients' QOL is inherently subjective, and definitions vary, it can be assessed on a basis of 3 major components: physical condition, psychological well-being, and social activities. The basic requirements of QOL assessments are: multidimensional construct, reliability, validity, sensitivity, responsiveness, appropriateness to question or use, and practical utility. The instruments to assess QOL can be disease specific or generic, depending on the context. In 1991 a prospective and systematic evaluation of QOL in implantable cardioverter-defibrillator (ICD) recipients was started at the University of Bonn: psychological profile and patient acceptance were assessed in 57 consecutive patients using a specifically designed questionnaire. The results of this pilot study demonstrated that the acceptance of the ICD was remarkably high. Restrictions on driving a vehicle may have a substantial impact on QOL in patients with ICDs. A specifically designed questionnaire was addressed to 47 European national delegates in order to determine their present practices and criteria utilized when advising driving restrictions to patients after ICD implantation. Of the 39 (83%) respondents, 22 (56%) cardiologists advised all patients to abstain from driving--13 (33%) advising permanent abstinence, while 26 (67%) recommended temporary driving abstinence for periods of 3-18 months (mean 9 +/- 4 months). Despite medical advice not to drive, one third of the patients resume driving; half of the patients resumed driving after 6 months, with the vast majority driving within 12 months after ICD surgery. Two patients experienced ICD discharges while driving, but no motor vehicle accident occurred. Another patient had a motor vehicle collision with a fatal outcome, which was not caused by loss of consciousness or ICD discharge. CONCLUSIONS: (1) Fatal accidents or ICD discharges while driving are a rare finding in ICD patients. (2) About half of the physicians always advise their patients to cease driving for a period of 9 +/- 4 months. Despite this medical advice, the majority of the patients resume driving within 6 months of ICD implantation. (3) Criteria used in advising driving abstinence are not uniform among physicians.

Attitude↗