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W Jung

Publications and source records attributed to W Jung.

At least 91 records · Page 5Linked to original sources
PubMed1998

Modulation of membrane potential by extracellular pH in activated microglia in rats.

Activation of cultured rat microglial cells by lipopolysaccharide (LPS) induced delayed rectifying outward K+ (I(K)) current. I(K) current was reported to have 'window current', playing a direct role in setting the membrane potential in activated microglia. We used whole-cell patch clamp method to measure the effect of extracellular pH on I(K) current. When pH was changed from 7.4 to 6.4, the activation curve of I(K) current shifted to the right by about 13 mV. Thus, extracellular acidification reduced the window current, resulting in membrane depolarization. These results suggest that extracellular pH regulate the membrane potential in activated microglia.

Animals↗
PubMed1998

Echocardiographic parameters for predicting maintenance of sinus rhythm after internal atrial defibrillation.

Chronic atrial fibrillation (AF), which is refractory to external electrical direct current shock and/or pharmacologic cardioversion, may be successfully cardioverted using internal atrial defibrillation. To avoid unnecessary procedures, it is important to be able to predict which patients will revert to AF. Thirty-eight patients with chronic AF underwent successful internal atrial defibrillation and were followed for 6 months after restoration of sinus rhythm. Left atrial (LA) diameter, left ventricular ejection fraction, maximum LA appendage area, and peak emptying velocities of the LA appendage were analyzed to determine which of these factors were associated with recurrence of AF. Forty-nine percent of patients had a recurrence of AF within 6 months following internal atrial defibrillation. The preprocedural ejection fraction (mean +/- SD 59 + 14% vs 57 + 13%, p = 0.63), LA diameter (4.2 +/- 0.6 cm vs 4.5 +/- 0.6 cm, p = 0.16), and LA appendage area (5.0 +/- 1.5 cm2 vs 5.8 +/- 1.5 cm2, p = 0.13) did not differ significantly between patients who maintained sinus rhythm and those who had recurrence of AF. Peak emptying velocities of the LA appendage before cardioversion were significantly lower in patients with recurrence of AF compared with patients who maintained sinus rhythm (0.26 +/- 0.1 m/s vs 0.49 +/- 0.17 m/s, p = 0.001). A peak emptying velocity <0.36 had a sensitivity of 82% and a specificity of 83% for predicting recurrence of AF.

Aged↗
PubMed1998

[Acute posterior wall infarct after factor VIII concentrate administration to a patient with severe hemophilia A].

HISTORY AND CLINICAL FINDING: A 69-year-old man with severe haemophilia A sustained an acute myocardial infarction (MI) after self-administration of 3000 units factor VIII over 10 min. On admission he had no signs of heart failure. INVESTIGATIONS: The ECG showed an acute posterior wall MI. Creatinekinase rose to a maximum of 321 U/l with a significant MB proportion. The echocardiogram demonstrated hypokinesia of the posterior wall. TREATMENT AND COURSE: After initial thrombolysis treatment with a total of 100 mg rtPA according to an accelerated scheme coronary angiography, performed because the symptoms persisted, revealed two-vessel disease. A subtotal stenosis of the right coronary artery was balloon-dilated with good primary results. Regular factor VIII substitution was temporarily administered with the aim of initially achieving high normal levels of factor VIII activity. CONCLUSION: Factor VIII substitution in haemophilia A may promote thrombotic complications. Thrombolytic treatment and balloon angioplasty of acute MI can be successfully performed even in patients with severe haemophilia A.

Aged↗
PubMed1998

[Circadian and weekly distribution of malignant ventricular arrhythmias in patients with coronary heart disease or dilatative cardiomyopathy who have an implanted cardioverter-defibrillator].

BACKGROUND AND OBJECTIVE: Epidemiological studies have demonstrated a circadian distribution of sudden cardiac death (SD) and acute myocardial infarction (AMI), with a maximum frequency of events during the morning hours. Recently an analysis of computer recordings of implanted cardioverter/defibrillators has confirmed these findings with respect to SD. The majority of these studies concerned patients with coronary heart disease. In a prospective study we evaluated the circadian and weekly distribution of malignant ventricular tachyarrhythmias (VTA) in patients with a nonischaemic cardiac disease, namely dilated cardiomyopathy (CMP), and those with coronary heart disease (CHD). PATIENTS AND METHODS: Over a mean period of 25 +/- 9 months computer-stored data and cardiac electrograms recorded from the implanted cardioverter/defibrillators (ICD) were analysed in 28 patients with CHD and 11 with DCMP. The circadian and weekly distribution of VTA was obtained, using customary arrhythmia classification and the stored and timed events. RESULTS: Patients with CHD had a maximal frequency of VTA or ventricular fibrillation (VF) during the morning, with a peak between 9 and 10 o/c, while those with DCMP were at a higher risk of VTA or VF in the later afternoon and early evening. Regarding the frequency of events during the week, a significantly higher incidence of VTA was recorded on Saturdays in those with CHD, but on Mondays and Wednesdays in those with DCMP. INTERPRETATION: The circadian and weekly distribution of VTA differs significantly between patients with CHD and those with DCMP. A possible reason for this difference may be different trigger mechanisms in the two types of cardiac disease, since transient ischaemia is unlikely to be the cause in patients with nonischaemic DCMP.

Cardiomyopathy, Dilated↗
PubMed1998

[Atrial defibrillator].

Atrial fibrillation (AF) is a frequent and costly health care problem representing the most common arrhythmia resulting in hospital admission. Total mortality and cardiovascular mortality are significantly increased in patients with AF compared to controls. In addition to symptoms of palpitations patients with AF have an increased risk of stroke and may also develop decreased exercise tolerance and left ventricular dysfunction. All of these problems may be reversed with restoration and maintenance of sinus rhythm. External electrical cardioversion has been a remarkably effective and safe method for termination of this arrhythmia. Originally described by Lown et al. in 1963, it has been a well accepted mode of acute therapy. However, this technique requires general anesthesia or heavy sedation. Internal atrial defibrillation has been evaluated as an alternative approach to the external technique for over 2 decades. Recent studies have shown that low-energy internal atrial defibrillation using biphasic shocks is an effective and safe means in restoring sinus rhythm in patients with AF and should be considered especially in patients in whom external cardioversion attempts have failed. IMPLANTABLE ATRIAL DEFIBRILLATOR: Recently, a stand alone IAD, the Metrix System (model 3000 and 3020), has entered clinical investigation. Atrial defibrillation is accomplished by a shock delivered between electrodes in the right atrium and the coronary sinus. The right atrium lead has an active fixation in the right atrium. The coronary sinus lead has a natural spiral configuration for retention in the coronary sinus, and can be straightened with a stylet. Both leads are 7 French in diameter and the defibrillation coils are each 6 cm in length. The electrodes may be placed using separate leads, or very soon by using a single bipolar lead. A separate bipolar right ventricular lead is used for R wave synchronization and post shock pacing. The Metrix defibrillator can be used to induce AF by using R wave synchronous shocks and can store intracardiac electrograms (EGMs) for up to 2 minutes from the most recent 6 AF episodes. The device can be programmed into one of the following operating modes: fully automatic, patient activated, monitor mode, bradycardia pacing only, and off. As AF is not life-threatening, in the automatic mode the device is only intermittently active in detecting and treating AF, and this "sleep wake-up" cycle interval is programmable. The device employs extensive processing both for detection and R wave synchronization. In April 1996, the phase I Metrix multicenter clinical trial was started. As of May 1997, a total of 51 Metrix systems had been implanted as part of the phase I multicenter clinical trial. Preliminary data suggest that both defibrillation thresholds and electrograms are stable over time (implant to 3 months). Detection accuracy has been excellent (100% specificity, 92.3% sensitivity) and there have been no errors of R wave selection for synchronization. No proarrhythmias have resulted from over 3700 shocks delivered. The device is effective in electrically converting 96% of the spontaneous episodes of AF. In 27% of episodes several shocks were required because of early recurrence of AF. In 5 patients, the atrial defibrillator was removed: 2 infections, 1 cardiac tamponade, 1 permanent loss of telemetry, 1 patient required His-Bundle ablation because of frequent episodes of drug refractory AF with rapid ventricular response. Initial clinical experience under controlled conditions with the Metrix system suggests that the implantable atrial defibrillator may offer a therapeutic alternative for a subgroup of patients with drug refractory, symptomatic, long lasting, and infrequent episodes of AF. Further efforts must be undertaken to reduce the patient discomfort associated with internal atrial defibrillation in an attempt to make this new therapy acceptable to a larger patient population with AF. (ABSTRACT TRUNCATED)

Atrial Fibrillation↗
PubMed1998

[The intraoperative measured stimulation impedance of pacemaker electrodes is not a predictor for their longevity].

UNLABELLED: As pacing impedance is inversely related to pacing current, the increase of pacing impedance additionally decreases pacing current. Whether the impedance measurement at implantation predicts the outcome during follow-up, was studied in 87 patients who received the VDD-single lead UniPass 425 connected to the pacemaker Unity (Sulzer Intermedics). The impedance changes between implantation and 6 months follow-up were assessed for each patient. Similar impedance values were defined, if the two measurements were within a range < or = -100 to +100 omega. Six-months impedance was lower or higher compared to implantation, if the difference exceeded > -100 or > +100 omega. At implantation, impedance was 535 +/- 98 omega (range: 333-811 omega) and significantly increased to 604 +/- 160 omega (range: 361-1150 omega) after 6 months. Mean difference between the two measurements was 69 +/- 162 omega (range: -336 bis + 560 omega). Similar impedance had 43 (implantation: 527 +/- 75 omega, 6 months: 531 +/- 87 omega), lower values 11 (implantation: 660 +/- 83 omega, 6 months: 494 +/- 73 omega) and higher values 33 patients (implantation: 503 +/- 99 omega, 6 months: 735 +/- 168 omega). Compared to the patients with similar impedance patients with lower impedance had a significantly higher impedance values at implantation. CONCLUSIONS: Pacing impedance increased significantly within 6 months after implantation. Pacing impedance changed > 100 omega in 51% of the patients. The long-term follow-up of pacing impedance can be predicted generally, but not for the individual patient.

Aged↗
PubMed1998

[QT syndrome: new diagnostic possibilities].

Electrocardiographic and clinical characteristics are currently used as diagnostic criteria for the long QT-syndrome. In borderline electrocardiographic findings associated with unclear syncope, it is often difficult to ensure or exclude long QT-syndrome. Schwartz and coworkers therefore created a point system as a guide in clinical decision making. In recent years genetic diagnostics have entered the arena of long-QT assessment. Aside from new insights into the pathophysiology of the long QT-disorder, it is expected that genetic diagnostics will offer substantial help to ascertain long QT-syndrome in patients with borderline electrocardiographic and clinical findings and improve risk stratification in long-QT family members. Performing linkage analysis, coupling of autosomal-dominant congenital long QT-syndrome (Romano-Ward Syndrome) to chromosomes 11 (LQT1/11p15.5), 3 (LQT3/3p21), 7 (LQT2/7q35), and 4 (LQT4/4q25-27) was demonstrated. More recently, the disease genes in long QT-syndrome 1, 2, and 3 could be identified. Analysis of the base-pair sequence allowed detection of several different mutations in different families illustrating genetic heterogeneity. Aside from diagnostic aspects, molecular genetics may also guide pharmacological therapy by identifying the specific ion-channel disorder leading to QT-prolongation and sudden death.

Chromosome Mapping↗
PubMed1998

Prospective evaluation of shoulder-related problems in patients with pectoral cardioverter-defibrillator implantation.

BACKGROUND: The pectoral approach to implantation of cardioverter defibrillators (ICDs) has become a standard in defibrillator therapy because of reduced generator size, weight, and volume. But the size of these devices is still comparable to the size of the early conventional antibradycardia pacemakers that were associated with a number of significant pocket- and shoulder-related problems after implantation in the pectoral region. In a prospective, single-center study of 50 patients with subpectoral implantation of a fourth-generation ICD, the ipsilateral shoulder joint was evaluated regarding active shoulder motility, shoulder-related pain, shoulder function, shoulder elevation, insertion tendinitis, and morphologic alterations of the shoulder. METHODS AND RESULTS: The shoulder was evaluated before implantation and at 3, 6, and 12 months after implantation. Shoulder motility was documented by evaluating active abduction, forward flexion, and external rotation. Shoulder-related pain and function were documented by the "Basic Shoulder Evaluation Form," insertion tendinitis was diagnosed by standardized palpation and the impingement test, and morphologic alterations were documented by ultrasound and radiograph of the shoulder. Three months after implantation, 20 (40%) patients had a reduced active abduction, 30 (60%) patients had an impaired active forward flexion, and eight (16%) patients had a reduced external rotation. Thirty-one (62%) patients reported shoulder-related pain or impaired shoulder function according to the "Basic Shoulder Evaluation Form." Twenty-four (48%) patients showed a shoulder elevation and 21 (42%) patients demonstrated clinical signs of insertion tendinitis. After 12 months the number of patients with reduced active abduction, forward flexion, and external rotation dropped to four (8%). Shoulder-related pain and reduced function were documented in seven (13%) patients, four (8%) patients still had shoulder elevation, and five (10%) patients still had signs of insertion tendinitis. None of the postoperatively performed ultrasounds or radiographs showed any pathologic shoulder alterations. No predictors for the occurrence of shoulder-associated problems could be found. CONCLUSIONS: (1) Decreased active shoulder motility, shoulder-related pain, reduced function, shoulder elevation, and insertion tendinitis of the ipsilateral shoulder joint are diagnosed in many patients 3 months after subpectoral ICD implantation. (2) After 12 months the number of patients with impaired shoulder motility, function, shoulder-related pain, shoulder elevation, and insertion tendinitis decreased significantly. (3) Ultrasound and radiographs of the ipsilateral shoulder showed no evidence of pathologic morphologic alterations after subpectoral ICD implantation. (4) No shoulder-associated problems required an operative revision of the subpectoral generator pocket.

Defibrillators, Implantable↗
PubMed1998

Prospective evaluation of the quality and long-term stability of atrial signals in non-thoracotomy defibrillation electrodes: comparison of four different endocardial electrograms.

UNLABELLED: Documentation of atrial signals in stored endocardial electrograms of modern implantable cardioverter-defibrillators (ICD) is a useful tool to classify the underlying arrhythmia leading to device therapy. Newest generations of ICD provide near- and far-field electrograms derived between various endocardial electrodes. The aim of this prospective study was to assess the quality and long-term stability of atrial signals in different far-field configurations including the active can housing. METHODS AND RESULTS: A total of 300 real-time endocardial electrogram recordings in 60 consecutive patients with a modern ICD in subpectoral position were analysed at the time of implant, pre-hospital discharge, 1, 3 and 12 months follow-up. Four different configurations were evaluated: right ventricular coil to can housing, can housing to pace/sense ring, right ventricular coil to pace/sense tip, and pace/sense tip to pace/sense ring. The best visibility of p-waves at an ECG-resolution of 0.5 mV/mm was seen in the can to coil configuration (77% of the patients). In the can to pace/sense ring electrogram p-waves could be observed in 58% of the patients. No p-waves were visible to pace/sense tip to pace/sense ring. At a resolution of 1.0 mV/mm p-waves were only visible in 10% of all patients exclusively in the can housing to right ventricular coil configuration. The results were stable (100% of the patients) over a follow-up of one year. CONCLUSIONS: Endocardial far-field electrograms, derived from the can housing and the right ventricular coil provide a p-wave visibility in 77% of the patients and demonstrate a long-term stability over at least one year, provided that the ECG-resolution is set at 0.5 mV/mm. Since the electrogram resolution of stored electrograms depends on the EGM-range, and the ECG-resolution at an EGM-range of 15 mV would be 1 mV/mm, the EGM-range is recommended to be programmed to 7.5 mV to ensure an ECG-resolution of at least 0.5 mV/mm for stored electrograms.

Algorithms↗
PubMed1998

Case report: inappropriate discharge of an implantable cardioverter-defibrillator caused by the combined count criterion.

We describe a rare case of an inappropriate defibrillator discharge during a sinus tachycardia with single fast sensed beats fulfilling the ventricular fibrillation rate criterion, activating the "combined count criterion," although the prevalent sinus tachycardia was inside a ventricular tachycardia rate zone, programmed to monitor only mode. The "combined count criterion" is a safety feature that ensures defibrillation therapy in case of a tachyarrhythmia inside the ventricular tachycardia detection zone, that is temporarily crossing the ventricular fibrillation detection rate. This case reports shows that there is a low but unpredictable risk of device therapy even in a zone programmed to monitor only mode. This phenomenon should be considered when a monitor only zone is installed for revelation of slower tachyarrhythmias.

Adult↗
PubMed1998

Electrical proarrhythmia: induction of inappropriate atrial therapies due to far-field R wave oversensing in a new dual chamber defibrillator.

This case report describes delivery of atrial therapies during a sinus tachycardia in a new dual chamber implantable cardioverter defibrillator inappropriately caused by far-field oversensing of ventricular beats in the atrial channel. Upon classification of the PR interval pattern, the rate criterion for an atrial tachycardia was fulfilled, and the device initiated high-frequency burst pacing as the first stage of programmed tiered atrial therapies. Atrial fibrillation subsequently was induced by high-frequency burst pacing, and eventually a programmed 10-J shock was delivered for successful termination of atrial fibrillation. The phenomenon of far-field oversensing of ventricular beats could be repeatedly observed during exercise testing and abolished by decreasing the atrial sensitivity.

Defibrillators, Implantable↗
PubMed1998

A new classification algorithm for discrimination of ventricular from supraventricular tachycardia in a dual chamber implantable cardioverter defibrillator.

INTRODUCTION: The high incidence of inappropriate therapies due to supraventricular tachycardia remains a major unsolved problem of implantable cardioverter defibrillators. We report a new detection formula for discrimination of ventricular tachycardia from supraventricular tachycardia in a patient with a dual chamber implantable cardioverter defibrillator and a new atrioventricular classification algorithm. METHODS AND RESULTS: The enhanced detection algorithm performs a stepwise arrhythmia analysis. The rhythm is first classified on the basis of cycle length. Each episode is then classified as supraventricular or ventricular on the basis of atrioventricular association, stability of circle length, and origin of acceleration. Sophisticated diagnostic information is provided by atrioventricular markers and electrogram recordings. Successful discrimination of two spontaneous episodes of ventricular tachycardia and supraventricular tachycardia is demonstrated. CONCLUSION: This new dual chamber detection algorithm may significantly improve the specificity of tachyarrhythmia detection without sacrificing sensitivity, thereby reducing the number of spurious shocks in patients with recurrent supraventricular tachycardias. Further studies are needed to assess the sensitivity and specificity of this detection algorithm.

Algorithms↗
PubMed1998

Acute and long-term effects of consecutive radiofrequency applications on conduction properties of the subeustachian isthmus in type I atrial flutter.

INTRODUCTION: Bidirectional conduction block at the subeustachian isthmus predicts long-term efficacy of atrial flutter ablation. Limited data are available on the incidence and outcome of minor conduction changes such as unidirectional or incomplete block. This prospective study sought to systematically assess discrete acute and long-term alterations of bidirectional conduction prior to a complete conduction block. METHODS AND RESULTS: In 41 patients with type I atrial flutter, pulse propagation through the subeustachian isthmus during low lateral and proximal coronary sinus pacing was documented and analyzed following each consecutive radiofrequency (RF) application. In cases of altered conduction properties and noninducibility of atrial flutter, patients were followed-up for 12 months. Three sets of results were found. First, following RF application, 23 patients presented a progressive conduction delay prior to a complete conduction block. Second, RF application did not always affect counterclockwise and clockwise conduction simultaneously or to the same extent. In 13 patients, an initial alteration of counterclockwise conduction was present before an alteration of clockwise conduction; in 5 patients, clockwise conduction was primarily affected. Third, the recurrence rate of typical atrial flutter was 9% (2/22) in patients with a complete bidirectional conduction block, 54% (7/13) in patients with unidirectional conduction block, and 100% (6/6) in patients with sole bidirectional conduction delay. CONCLUSION: In 50% of the patients, consecutive RF applications resulted primarily in a progressive conduction delay rather than a sudden conduction block. Since counterclockwise and clockwise conduction were not always affected simultaneously or to the same extent, lateral as well as septal pacing is recommended for improvement of bidirectional conduction block. Normalization of primarily altered conduction and, therefore, recurrence of atrial flutter are high in all patients without bidirectional block.

Adult↗