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Biomedical subjects

B Lüderitz

Publications and source records attributed to B Lüderitz.

At least 235 records · Page 13Linked to original sources
PubMed1995

Pacemaker function during radiofrequency ablation.

There are increasing numbers of radiofrequency current ablation procedures being reported. Selected patients have antitachycardia or antibradycardia pacemakers. The pacemaker behavior during and after ablation procedures differs widely. We report on the pacemaker reaction of 25 patients with 13 different devices, most with unipolar electrodes. Sensing failures were observed in 8 (32.0%) and pacing failures in 4 (16.0%) patients. Prolonged pauses and induction of tachyarrhythmias were observed. No pacemaker damage was seen although it is reported by other investigators. We recommend deactivation of implanted generators and an external bipolar pacing electrode. Manufacturers should focus their attention on this problem and protect the generators and their functions for 500 kHz radiofrequency current.

Adult↗
PubMed1995

Effects of nuclear magnetic resonance imaging on cardiac pacemakers.

Patients with cardiac pacemakers are currently restricted from nuclear magnetic resonance imaging (MRI). The aim of the study was to analyze the influence of MRI on new generation pacemakers. Tests were performed using a phantom model with seven dual chamber and two single chamber systems in a 0.5 Tesla MRI scanner. Monitoring by telemetry and oscillography were used during the standard clinical scan sequences as well as a pacemaker inquiry after each sequence. Spin echo, gradient echo, and fast field echo sequences were performed with the following stimulation modes: VVI, VVIR, VOO, DDD, DDDR, and DOO. On entering the static magnetic field, the reed switch was activated followed by asynchronous stimulation. The subsequent scan showed no influence on the stimulation function nor on the pacemaker program. Event counter function remained intact. Pacemakers with automatic mode switching to demand pacing or programmed inactivation of the reed switch were triggered in the dual chamber mode and were inhibited in the one chamber mode during the scan. Alterations of pacemaker program or rapid pacing were not observed. MRI scan could induce voltage as high as intracardiac signals, but the stimulation threshold of the heart was not reached. Thus, pacemakers should be programmed in the asynchronous mode during scan to avoid inhibition and trigger mechanism.

Acrylic Resins↗
PubMed1995

Echocardiographic imaging of coronary sinus diverticula and middle cardiac veins in patients with preexcitation syndrome: impact on radiofrequency catheter ablation of posteroseptal accessory pathways.

To determine the value of echocardiography for identifying coronary sinus (CS) diverticula and middle cardiac veins (MCVs) in patients with posteroseptal accessory pathways (PAPs), transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 18 consecutive patients with PAP and in 15 control subjects with left lateral accessory pathway before CS angiography. The size, shape, and location of CS diverticula and MCV were described and compared to angiography. TEE and angiography were concordant for the identification of diverticula (n = 5) and agreed for depicting MCV in 22 of the 27 cases. TTE revealed 4 of 5 diverticula and identified 4 of 27 MCV (P < 0.001). Fourteen MCV but no diverticula were found in the control subject. There was no significant difference between transesophageal and angiographic measurements for the width (23.5 +/- 4.9 vs 26.8 +/- 6.6 mm) and height (13.5 +/- 3.8 vs 15.7 +/- 3.4 mm) of the diverticula, and the width (3.5 +/- 0.7 vs 3.7 +/- 0.6 mm) of MCV. TEE underestimated the length of the MCV (12.0 +/- 1.8 vs 27.2 +/- 6.0, P < 0.001). Delivery of radiofrequency energy within the neck of a diverticulum or within an MCV was successful in 5 of 5, and 6 of 13 cases in patients with PAPs, respectively. In conclusion, echocardiography was as reliable as angiography for detecting and describing CS diverticula and MCV in patients with preexcitation syndrome. Echocardiography is recommended prior to electrophysiological study because it may simplify radiofrequency catheter ablation.

Adult↗
PubMed1995

Impact of the local atrial electrogram in AV nodal reentrant tachycardia: ablation versus modification of the slow pathway.

INTRODUCTION: The purpose of this study was to determine the predictors of successful ablation versus modification sites of the slow pathway in patients with AV nodal reentrant tachycardia. Complete elimination of slow pathway conduction ("ablation") is considered to be an appropriate endpoint during radiofrequency (RF) current delivery, whereas the persistence of residual slow pathway conduction with or without single echo beats ("modification") may be indicative of tachycardia recurrence. METHODS AND RESULTS: Of 131 patients, 71 consecutive patients were followed for 15.1 +/- 7.6 months. After elimination of inducible AV nodal reentrant tachycardia in all patients, residual slow pathway conduction (modification) persisted in 38 patients, whereas complete elimination of slow pathway conduction (ablation) was documented in 33 patients. Including electrophysiologic study after 5 to 7 days and after 3 to 6 months, 6 (8.4%) patients had recurrences: 5 with residual slow pathway conduction after the procedure and 1 with complete elimination of slow pathway conduction (P < 0.05). As compared with modulated sites, ablation sites of the slow pathway were characterized as follows: (1) duration of the local atrial electrogram (AEGM) (66.7 +/- 10.2 vs 54.1 +/- 12.6 msec, P < 0.01); (2) interval from the end of the AEGM to onset of His-bundle deflection (4.4 +/- 8.2 vs 16.1 +/- 9.3 msec, P < 0.01); and (3) number of peaks of the AEGM as an indicator of fractionation (4.1 +/- 0.7 vs 3.0 +/- 0.8, P < 0.01). The rate of junctional tachycardias (103.4 +/- 12.1 vs 102.1 +/- 16.9 per min), the AV ratio (0.4 +/- 0.5 vs 0.5 +/- 0.5), the number of RF current deliveries (4.1 +/- 4.4 vs 4.5 +/- 4.4), the duration of the procedure (124.1 +/- 45.3 vs 125.6 +/- 42.3 min), and the fluoroscopy time (15.5 +/- 10.8 vs 16.6 +/- 9.6 min) as well as power and total energy of RF current deliveries and the anatomically calculated catheter position at the successful site were not statistically different. A subset analysis in patients who received only a single RF application showed the same results for both groups. Patients without recurrence (n = 65) were found to have longer duration of the AEGM (61.9 +/- 14.6 msec) and a shorter interval from the end of AEGM to the onset of His-bundle deflection (10.1 +/- 12.2 msec) than patients with recurrence (n = 6) (47.5 +/- 7.5 msec and 20.8 +/- 12.8 msec, respectively). CONCLUSION: Complete ablation of the slow pathway resulted in a lower recurrence rate. The complete ablation approach is feasible using precisely analyzed local AEGMs to guide RF current in AV nodal reentrant tachycardia in a short procedure time.

Adult↗
PubMed1995

Slowing of the ventricular rate during atrial fibrillation by ablation of the slow pathway of AV nodal reentrant tachycardia.

INTRODUCTION: The mechanisms whereby radiofrequency catheter modification of AV nodal conduction slows the ventricular response are not well defined. Whether a successful modification procedure can be achieved by ablating posterior inputs to the AV node or by partial ablation of the compact AV node is unclear. We hypothesized that ablation of the well-defined slow pathway in patients with AV nodal reentrant tachycardia would slow the ventricular response during atrial fibrillation. METHODS AND RESULTS: In 34 patients with dual AV physiology and inducible AV nodal reentrant tachycardia, atrial fibrillation was induced at baseline and immediately after successful slow pathway ablation and at 1-week follow-up. The minimal, maximal, and mean RR intervals during atrial fibrillation increased from 353 +/- 76, 500 +/- 121, and 405 +/- 91 msec to 429 +/- 84 (P < 0.01), 673 +/- 161 (P < 0.01), and 535 +/- 98 msec (P < 0.01), respectively. These effects remained stable during follow-up at 1 week. The AV block cycle length increased from 343 +/- 68 msec to 375 +/- 60 msec (P < 0.05) immediately and to 400 +/- 56 msec (P < 0.01) at 1-week follow-up. The effective refractory period of the AV node prolonged from 282 +/- 83 msec to 312 +/- 89 msec and to 318 +/- 81 msec after 1 week (P < 0.05), respectively. CONCLUSION: This study shows a decrease in ventricular response to pacing-induced atrial fibrillation after ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Since the AV nodal conduction properties could be defined, this study supports the hypothesis that the main mechanism of AV nodal modification in chronic atrial fibrillation is caused by ablation of posterior inputs to the AV node.

Atrial Fibrillation↗
PubMed1995

Radiofrequency catheter ablation of septal accessory pathways.

Catheter ablation of septal accessory pathways in preexcitation syndrome is associated with special problems because of the risk of impairment of atrioventricular nodal conduction during ablation of anteroseptal and midseptal pathways. The complex morphology of the posteroseptal space has special problems for ablation with unclear location of the ablation catheter in the left or right atrial or ventricular cavum, in the coronary sinus, ventricular veins, or the neck of a coronary sinus diverticulum. Therefore, the visualization of the pyramidal space using echocardiographic investigations before the ablation procedure and retrograde coronary sinus phlebography during the ablation session has proven to be very helpful in placement of the electrode to the successful position. Reported herein are the techniques, results, and problems of radiofrequency ablation of 30 patients with septal accessory pathways compared to published data.

Adult↗
PubMed1995

Prognostic analysis and predictive rule for outcome of hospital-treated community-acquired pneumonia.

In community-acquired pneumonia (CAP) mortality may be reduced by early identification of patients requiring intensive care treatment. The purpose of this study was to determine prognostic factors of outcome in patients with CAP in order to establish a clinically applicable discriminant rule. Ninety three episodes of CAP in 92 patients were retrospectively reviewed with regard to epidemiological, clinical, laboratory and microbiological data. The prognostic analysis included a univariate as well as a multivariate approach, in order to identify parameters associated with death using the Cox regression hazard function in a backward stepwise selection model. The three parameters found to contribute most to the significance of the model were used in a discriminant rule for classification of outcome. The parameters found to be significantly different between survivors and non-survivors were heart rate, systolic and diastolic as well as mean blood pressures, leucocyte count, percentage of lymphocytes, and lactate dehydrogenase (LDH) values. The multivariate analysis revealed that heart rate, systolic arterial pressure, and LDH serum levels were most closely associated with fatal outcome. A prognostic rule composed of the variables heart rate > or = 90 beats.min-1, systolic arterial blood pressure < or = 80 mmHg, and LDH > or = 260 U.l-1 achieved a sensitivity of 77%, a specificity of 75%, and positive and negative predictive values of 42 and 93%, respectively. It was associated with a six fold increased risk of fatal outcome. In conclusion, heart rate, systolic blood pressure, and LDH values were most closely associated with death in a multivariate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1995

[Cerebrogenic ECG changes after severe subarachnoid hemorrhage from an internal carotid artery aneurysm--differential diagnosis of acute myocardial infarct].

ECG-changes simulating acute posterior myocardial infarction were observed in a 62-year-old woman 16 days after acute subarachnoid hemorrhage. An acute myocardial ischemia was excluded by enzyme laboratory tests and by coronary angiography. The transient ECG-changes can be explained by short-term spasms of small distal arterioles in the heart, which were affected by a derangement of autonomic function. The present case demonstrates ECG-changes in a patient with subarachnoid hemorrhage very late after the acute event. Therefore, patients with intracranial hemorrhage should have a prolonged electrocardiographical aftercare. ECG-changes in patients with subarachnoid hemorrhage were discussed as a specific parameter describing the degree of intracranial damage and as a predictive value for a poor outcome. Because of ventricular arrhythmias and the occurrence of sudden cardiac death in patients with subarachnoid hemorrhage critical care monitoring should be performed after detection of new ECG-changes.

Autonomic Nervous System↗
PubMed1995

[Extrasystole].

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Cardiac Complexes, Premature↗
PubMed1995

[Prognostic value of signal averaged ECG in dilated cardiomyopathy with spontaneous and induced ventricular tachyarrhythmias].

UNLABELLED: Ventricular late potentials in signal-averaged ECG are a predictor of ventricular tachyarrhythmias in patients with coronary artery disease. The role of signal-average ECG in non-ischemic dilated cardiomyopathy has not been defined yet. We studied the prognostic impact of an abnormal signal-averaged ECG in 31 patients with non-ischemic dilated cardiomyopathy. All signal-averaged ECG recordings were analyzed by time-domain analysis as well as by frequency analysis with spectrotemporal mapping. RESULTS: In 13 (42%) patients time domain analysis and in 9 (29%) patients frequency analysis was found to be abnormal. During follow-up (13 +/- 7 months) seven (23%) patients developed spontaneous ventricular tachyarrhythmias. The mean ejection fraction and the results of programmed ventricular stimulation did not differ significantly between patients with and without clinical episodes. Abnormal time domain analysis was found in five (71%) patients with and in eight (33%) patients without spontaneous tachyarrhythmias (p = 0.07), and abnormal frequency analysis in 3 (43%) patients versus 6 (25%) patients (p = 0.36). The low-amplitude-signal duration was significantly increased in patients with tachyarrhythmias (p = 0.008). Ventricular tachyarrhythmias occurred in 38% of patients with abnormal time domain analysis and in 33% of patients with abnormal frequency analysis. In patients with normal signal-averaged ECG the incidence reached 11% and 18%. For time-domain analysis the sensitivity was 71%, specificity 67%, positive predictive value 38%, and negative predictive value 89%, for spectrotemporal mapping 43%, 75%, 33%, and 82%, respectively. The incidence of electrophysiologically inducible ventricular tachyarrhythmias in patients with abnormal signal-averaged ECG exceeded that in patients with normal findings. CONCLUSION: In patients with non-ischemic dilated cardiomyopathy a normal signal-averaged ECG is associated with a reduced occurrence of ventricular tachyarrhythmic events. Thus, signal-averaged ECG contributes to the evaluation of these patients. The negative predictive value exceeded the positive predictive value.

Adult↗
PubMed1995

[Adenosine].

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Adenosine↗
PubMed1995

[Sleep apnea and cardiovascular risk].

Obstructive sleep apnea syndrome (OSAS) is the most important form of sleep-related breathing disorders due to its high prevalence and its potential for developing cardiovascular diseases. The increased morbidity of these patients is explained by the coincidence with cardiovascular diseases, and the increased mortality of untreated patients is due to cardiovascular complications, which depend on the degree of the breathing disorder. Heavy snoring, as a partial obstruction of the upper airways, and OSAS are independent risk factors for the development of cardiovascular diseases and stroke. Causal associations exist between acute hemodynamic changes, pressure and volume load, changes in the humoral and the central nervous system, and blood gas alterations during the obstructive apnea and the long-term condition due to OSAS. Obstructive apnea can be divided into an early phase, a late phase, and a phase of the postapneic hyperventilation with respect to hemodynamic changes, blood gas alterations, and the autonomic nervous system. The most striking changes in these parameters are seen at the end of apnea and in the first resumption of breathing, with an increase in systemic and pulmonary blood pressure, decrease in stroke volume, and a distinct change in heart rate. Manifestation of systemic hypertension even in the awake state is promoted by changes in the volume system, with activation of neurohumoral changes and by a resetting of baro- and chemoreceptors. Similar mechanisms are discussed in the development of pulmonary hypertension. In this circumstance the role of hypoxemia as a causal factor for pulmonary hypertension or as a consequence due to structural changes of the pulmonary vessels is controversial. OSAS is frequent in patients with coronary heart disease and these patients must be classified as a particular risk group because of apnea-associated silent myocardial ischemia and electric instability of the myocardium. The occurrence of arrhythmia in patients with OSAS is closely related to the apnea and hyperventilation events and depends on the sympathovagal balance. Early diagnosis and suitable therapy of patients at risk not only abolishes the sleep-related breathing disorder but also improves long-term outcome.

Autonomic Nervous System↗
PubMed1995

Clinical characteristics and outcome of Pneumocystis carinii pneumonia in HIV-infected and otherwise immunosuppressed patients.

The factors contributing to unequal mortality rates following Pneumocystis carinii pneumonia (PCP) in different groups at risk are poorly understood. We therefore compared the first episodes of PCP without prophylaxis in human immunodeficiency virus infected (HIV) and otherwise immunosuppressed patients in this retrospective study. A total of 58 HIV-infected and 16 otherwise immunosuppressed patients were analysed. The comparison included epidemiological, clinical, laboratory, radiological and microbiological data, as well as therapy and clinical course. A prognostic analysis was performed using a logistic regression model. The mortality was significantly different in the two groups (HIV group 17 versus non-HIV group 50%). Renal transplant patients had a higher survival rate as compared to malignancy or collagen vascular disease as underlying diseases at risk. Acute respiratory failure was more common in the non-HIV group. Variables found to be significantly associated with lethal outcome in univariate analysis were alveolar to arterial pressures difference for oxygen (P(A-a),O2), haemoglobin, platelet count, total protein, serum albumin, and gamma-globulins in the HIV-group, and serum albumin in the non-HIV group. In the multivariate analysis of the HIV group, platelet count and gamma-globulins remained independent prognostic factors. In conclusion, in the HIV-group, mortality is closely related to the severeness of PCP as well as to the severeness of the acquired immune deficiency syndrome (AIDS) disease. In the non-HIV group, malignancy and collagen vascular disease as underlying conditions at risk account for the high mortality rate. Its severeness was mainly reflected by serum albumin, which represented the only variable found to be significantly associated with death in both groups.

AIDS-Related Opportunistic Infections↗
PubMed1995

[Junctional arrhythmias in radiofrequency modification of the atrioventricular node].

UNLABELLED: Accelerated junctional rhythm (JR) is known as a response of the atrioventricular node to thermal injury and a common finding in radiofrequency ablation for AV node reentrant tachycardia. We studied JR during 1314 radiofrequency current deliveries in 172 patients with AV node reentrant tachycardia or paroxysmal atrial fibrillation in relation to the ablation result. JR in a successful RF delivery were characterized by cycle length and conduction. RESULTS: Selective slow pathway ablation was performed in 100 patients (Group A), selective fast pathway ablation in 41 patients (Group B), and total AV junction ablation in 31 patients (Group C). A successful radio-frequency ablation without JR was rare (sensitivity: 98.8%; specificity: 51.2%). JR during slow pathway ablation had a longer cycle length (X +/- SD; CL: 494 +/- 138 ms) and a lower cycle length dispersion (delta CL: 178 +/- 199 ms) than JR during fast pathway ablation (CL: 399 +/- 108 ms; delta CL: 345 +/- 145 ms) or before total AV block (CL: 439 +/- 163 ms; delta CL: 338 +/- 195 ms). JR with bundle branch block aberration or ventriculoatrial block were more often found in group B and group C than in group A (BBB: 29% vs. 23% vs. 12%; VA-Block: 80% vs. 82% vs. 33%). Group B and group C did not differ significantly. CONCLUSION: JR leading to fast pathway ablation or heralding total AV block are characterized by a short cycle length, wide cycle length dispersion, and predominantly present ventriculoatrial block. Thus, JR is a useful marker to prevent inadvertent AV block in slow pathway ablation.

Adult↗
PubMed1995

[Sleep-related respiratory disorders in patients with implantable cardioverter/defibrillator devices--relationship between left ventricular function and respiratory disorder].

In order to detect sleep related breathing disorders (SRBD), 15 patients (6 with dilated cardiomyopathy [DCM], 9 with coronary heart disease [CHD], mean age 58 +/- 13 years) with implantable cardioverter/defibrillator [ICD] underwent polysomnography. A SRBD could be diagnosed in 27% of cases (n = 4; 3 DCM, 1 CHD). The reduction of the ejection fraction (EF) (normal, mild-to-moderate and severe, respectively) and the quality of sleep-related disturbances (normal, obstructive, and central/periodic) were significantly associated. In addition, in patients with DCM, the reduction of the EF correlated significantly with the amount of nocturnal oxygen-desaturation.

Adult↗
PubMed1994

Multiplane transesophageal echocardiographic assessment of mitral regurgitation by Doppler color flow mapping of the vena contracta.

Assessment of the severity of mitral regurgitation (MR) by Doppler color flow mapping is limited by dependence of jet area on hemodynamic and technical variables. The width of the MR jet at its origin may be less dependent on hemodynamic variables, and thus should more accurately reflect the severity of MR. Doppler color flow mapping was performed in 80 subjects by transesophageal echocardiography (TEE) within 48 hours of catheterization. Width of the MR jet at its vena contracta was measured by both single plane and multiplane TEE and compared with the angiographic grade of MR and regurgitant volume. The width of the MR jet correlated closely with angiographic grade by both methods. A jet width > or = 6 mm identified angiographically severe MR with a sensitivity and specificity of 100% and 83% by single-plane TEE, and 95% and 98% by multiplane TEE. The sensitivity and specificity for detecting a regurgitant volume > or = 80 ml was 93% and 76% for single-plane TEE, and 86% and 95% for multiplane TEE. Thus, the width of the MR jet at its vena contracta by Doppler color flow mapping is an accurate marker of the severity of MR. By virtue of its ability to obtain orthogonal views specifically oriented to mitral leaflet coaptation, multiplane TEE is superior to single-plane TEE in assessing MR jet width.

Blood Flow Velocity↗
PubMed1994

[Cardiac manifestations in advanced HIV infection].

Incidence, type and clinical significance of cardiac involvement in advanced HIV infection was determined in 32 patients (30 men, two women; mean age 34.2 [21-52] years; mean CD4-cell number 52.2 [0-192]/microliters) over a period of 31 months. Any cardiac involvement was assessed diagnostically by one- and two-dimensional and Doppler echocardiography, complemented by other examinations and results of treatment. 14 patients (43.8%) had abnormal cardiac findings, presumably AIDS-associated. This included left ventricular pump dysfunction of various degrees of severity (n = 11), left ventricular dilatation (n = 2), pericardial effusion (n = 11), as well as cor pulmonale in primary pulmonary arterial hypertension (n = 2). In one patient the first manifestation of AIDS was tubercular pericarditis; in two patients there was a likely connection to disseminated pneumocystis infection and toxoplasmosis, respectively. In 11 patients no specific cause was found for the cardiac involvement. Nine of the 14 patients (64%) had symptoms due to the cardiac involvement. These findings indicate that the incidence and clinical significance of cardiac involvement must be taken into account in any treatment concept for AIDS.

AIDS-Related Complex↗