Biomedical subjects

W Jung

Publications and source records attributed to W Jung.

At least 19 recordsLinked to original sources

PubMed1995

Heart rate to work rate relation throughout peak exercise in normal subjects as a guideline for rate-adaptive pacemaker programming.

We investigated the physiologic heart rate (HR) to work rate (WR) relation throughout peak exercise in normal subjects as a guideline for rate-adaptive pacemaker slope programming. The study group consisted of 41 middle-aged subjects (22 men and 19 women) without evidence of cardiopulmonary disease. Peak-exercise stress tests were performed on a calibrated treadmill by using the symptom-limited "ramping incremental treadmill exercise" (RITE) protocol. The HR response, oxygen uptake, and treadmill workload increments were assessed simultaneously. The HR/WR slope, as determined using linear regression analysis, was 0.37 +/- 0.13 beats/min/W for the entire study group, which indicates an upper range increase of 5 beats/10 W increase of external treadmill work performed, using the mean value +/- 1 SD. Men generated an HR/WR slope of 0.32 +/- 0.09 beats/min/W, and women, 0.43 +/- 0.15 beats/min/W, indicating a significant sex-related difference in the HR/WR relation (p < 0.01). Thus, to achieve an appropriate matching of HR with patient effort, rate-adaptive pacemakers should generate an average increase of approximately 5 beats per increase in 10 W of external treadmill work. The HR/WR relation can easily be determined to provide the clinician with a minimal check system to avoid a hyper- or hypochronotropic paced response to exercise.

Adult↗

PubMed1995

The role of lymphocyte subsets and adhesion molecules in T cell-dependent cytotoxicity mediated by CD3 and CD28 bispecific monoclonal antibodies.

The cure of human Hodgkin's tumors heterotransplanted into SCID mice can be achieved by two bispecific monoclonal antibodies (Bi-mAb) directed against the tumor-associated CD30 antigen and CD3 and CD28, respectively, and normal peripheral human blood T cells. We investigated the role of lymphocyte subsets and adhesion molecules in this Bi-mAb-mediated cytolysis. CD4+ lymphocytes were the most rapidly expanding subpopulation, but Bi-mAb-directed cytotoxicity was mediated preferentially by CD8+ lymphocytes and effector cells belonging to the CD45RO+ "memory" pool. Blocking of the LFA-1/ICAM-1 or CD2/LFA-3 adhesion pathways by mAb decreased Bi-mAb-mediated cytotoxicity. This was not due to inhibition of aggregate formation between Bi-mAb-coated T lymphocytes and target cells. Cross-linking of LFA-1 or CD2 molecules on lymphocytes prestimulated with Bi-mAb bound to CD3 and CD28 antigen lead to a more pronounced and prolonged rise in the intracellular concentration of free Ca2+. Additional CD2 cross-linking resulted in the tyrosine phosphorylation of distinct proteins. These findings indicate that adhesion molecules play a critical role and function as co-stimulatory signals rather than as cellular contact mediators in CD3 and CD28 Bi-mAb-stimulated T lymphocytes.

Antibodies, Bispecific↗

PubMed1995

Prospective study of retrograde coronary venography in patients with posteroseptal and left-sided accessory atrioventricular pathways.

The morphologic features of the coronary vein system was prospectively studied with retrograde venography in 117 patients with left-sided (78 patients) and posteroseptal accessory pathway (39). Findings were compared with accessory pathway localization. A mean of 3.3 +/- 1.5 venous branches draining into the coronary sinus or the great cardiac vein could be visualized. The morphologic condition was described and classified. Incidence, morphologic condition, and distribution did not differ between left-sided and posteroseptal accessory pathway. Venous abnormalities including ectasy, diverticulum, narrowing, angulation, and hypoplasia occurred in 22.2%. Diverticulum and narrowing were present in posteroseptal accessory pathway only and always related to the successful ablation site. In patients with left-sided accessory pathway, ectasy, angulation, and hypoplasia were found. Anomalies were less frequent (9% vs 43.6%, p < 0.001) and had no relation to accessory pathway localization. However, the successful ablation site was in 42.3% located < 5 mm to an angiographically visualized venous branch. In conclusion, posteroseptal accessory pathways are often related to coronary sinus abnormalities. In patients with a left-sided accessory pathway venous malformation is uncommon, whereas a close anatomic relation exists between accessory pathway localization and venous ventricular branches.

Adolescent↗

PubMed1995

Randomized comparison of aspirin and phenprocoumon for prevention of right-sided thromboembolic complications associated with transvenous defibrillation leads.

Death due to pulmonary embolism caused by thrombosis formation along a pacing wire has been reported in patients with antibradycardia pacemakers. The purpose of this prospective and randomized study was to evaluate the effects of prophylactically assigned aspirin (100 mg per day) or phenprocoumon (a coumarin derivative) on the incidence of right-sided thromboembolic complications associated with transvenous defibrillation leads. Multiplane transoesophageal echocardiography and pulmonary scintigraphy were performed in 62 consecutive patients immediately and 6 +/- 2 months after transvenous defibrillator implantation. Aspirin or phenprocoumon was administered to the patients in a randomized and parallel manner. By means of multiplane transoesophageal echocardiography and pulmonary scintigraphy no thromboembolic events were observed immediately after transvenous defibrillator implantation. After 6 +/- 2 months, however, multiplane transoesophageal echocardiography disclosed thrombi on the transvenous leads in 13 of 62 patients (21%) despite antithrombotic therapy. At the same time, pulmonary scintigraphy did not reveal any defects compatible with pulmonary embolism. Although thrombi occurred in only four patients treated with phenprocoumon, but in nine patients receiving aspirin, this difference was statistically insignificant. Other variables associated with the occurrence of thrombosis formation were not identified. One fatal intracranial haemorrhage occurred in the phenprocoumon group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The "low intensity treadmill exercise" protocol for appropriate rate adaptive programming of minute ventilation controlled pacemakers.

The objective of rate adaptive pacemakers that measure minute ventilation by transthoracic impedance is to simulate the physiological relationship of the sensed signal to the sinus node response during exercise, thus achieving an appropriate matching of heart rate with patient effort. The purpose of this study was to determine the physiological relationship between heart rate and minute ventilation (HR/VE) during peak exercise testing in order to develop a database for appropriate rate adaptive slope programming of minute ventilation controlled pacemakers. Due to several clinical limitations of peak exercise testing, it was additionally determined whether the 35-watt "low intensity treadmill exercise" (LITE) protocol can be used as a substitute for peak exercise test using the "ramping incremental treadmill exercise" (RITE) protocol in order to assess the correct HR/VE slope below the anaerobic threshold. The stress tests were performed on a treadmill with the collection of breath-by-breath gas exchange. Linear regression analysis was used to determine the HR/VE slope below and above the anaerobic threshold and during the early, dynamic phase of low intensity exercise with the RITE and LITE protocols, respectively. The results of this testing in 41 healthy subjects demonstrated that the HR/VE relationship throughout treadmill exercise using the RITE protocol was not linear but curvilinear in nature, with a steeper HR/VE slope of 1.54 +/- 0.51 below versus 1.15 +/- 0.37 above the anaerobic threshold (P < 0.005). The HR/VE slope determined during the early, dynamic phase of the LITE protocol (1.58 +/- 0.88) did not differ from the HR/VE slope from rest to anaerobic threshold obtained using the peak exercise RITE test (1.54 +/- 0.51; P = 0.79). Rate adaptive pacing should simulate the curvilinear relationship between heart rate and minute ventilation from rest to peak exercise. The HR/VE slope determined during the early, dynamic phase of low intensity exercise represents the HR/VE slope derived from the RITE protocol below the anaerobic threshold. According to the peak exercise database, the slope above anaerobic threshold can easily be calculated as a percentage of the slope below the anaerobic threshold. The LITE protocol can, therefore, be effectively performed as a substitute for peak exercise stress tests to determine the correct pacemaker rate response factor in order to obtain a physiological heart rate to minute ventilation relationship for the appropriate matching of paced heart rate with patient effort.

Anaerobic Threshold↗

PubMed1995

Intravenous adenosine during atrioventricular reentrant tachycardia: induction of atrial fibrillation with rapid conduction over an accessory pathway.

Adenosine is considered to be a safe agent for termination of orthodromic atrioventricular reentrant tachycardia in patients with accessory pathways. A case with initially successful accessory pathway ablation and without preexcitation during sinus rhythm is presented, in which intravenous adenosine (6 mg) during orthodromic tachycardia was followed by atrial fibrillation and sudden onset of preexcitation with subsequent rapid ventricular response with moderate hemodynamic compromise.

Adenosine↗

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

[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

[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↗

PubMed1994

Cure of xenografted human tumors by bispecific monoclonal antibodies and human T cells.

Tumor immunotherapy should increase both the number of T cells that kill the tumor and the likelihood that those cells are activated at the tumor site. Bispecific monoclonal antibodies (Bi-mAbs) were designed that bound to a Hodgkin's tumor-associated antigen (CD30) on the tumor and to either CD3 or CD28 on the T cell. Immunodeficient mice were cured of established human tumors when mice were treated with both the CD3-CD30 and the CD28-CD30 Bi-mAbs and then given human peripheral blood lymphocytes that had been incubated with the CD3-CD30 Bi-mAb and cells that expressed CD30. The enrichment of human T cells within the tumor and the fact that established tumors can be cured may indicate in situ activation of both the T cell receptor and the costimulatory pathway.

Animals↗

PubMed1994

Interactions between drugs and devices: experimental and clinical studies.

It is important to understand the potential interactions between the implantable cardioverter defibrillator (ICD) and antiarrhythmic therapy in patients who receive pharmacologic therapy as an adjunct to ICD therapy. In our cohort of 101 patients, antiarrhythmic agents were prescribed in 67% of the patients during long-term therapy for the following reasons: to suppress ventricular tachycardia/ventricular fibrillation episodes (50%), to lower the rate of ventricular tachycardia (19%), to prevent supraventricular tachyarrhythmia (21%), and for other reasons (10%). The potential influence of antiarrhythmic drugs on the defibrillation threshold (DFT) is the most important issue. In animal studies lidocaine increased the DFT in a dose-dependent manner. Quinidine, procainamide, propafenone, and flecainide did not affect the DFT or, in some cases, led to a small increase. Sotalol even decreased the energy requirements for internal defibrillation. In a prospective investigation we were able to document a significant increase of DFT (from 14.1 + 3.0 to 20.9 + 5.4 J, p < 0.001) by the use of amiodarone (400 mg/day), whereas this effect was not found in patients who received mexiletine (720 mg/day). In conclusion, the DFT or the safety margin for defibrillation should be known before antiarrhythmic agents are administered to patients with an ICD. In case of a small safety margin, the DFT should be reassessed after antiarrhythmic drug therapy is begun.

Animals↗

PubMed1994

Clinical efficacy of shock waveforms and lead configurations for defibrillation.

A randomized, prospective comparison of the defibrillation efficacy of various shock waveforms and nonthoracotomy lead configurations was performed in five distinct patient groups undergoing implantation of a cardioverter defibrillator. In the first group using a bidirectional lead configuration, there was no significant difference in the mean defibrillation threshold (DFT) between simultaneous and sequential monophasic shocks (17.8 +/- 5.8 joules versus 17.3 +/- 2.7 joules). In the second group using a bidirectional lead configuration, the mean DFT was 21.9 +/- 7.3 joules with monophasic shocks and 14.9 +/- 5.0 joules with biphasic shocks (p < 0.001). In the third group using a unidirectional lead configuration, the mean DFT was significantly higher (p < 0.001) with monophasic shocks (22.1 +/- 4.2 joules) compared with biphasic shocks (15.0 +/- 5.4 joules). In the fourth group, an intraindividual comparison with monophasic shock waveforms showed no significant differences in DFT using either a bidirectional (21.3 +/- 5.8 joules) or a unidirectional (21.7 +/- 2.6 joules) lead configuration. In the fifth group, a simplified unipolar transvenous defibrillation lead system ("active can") demonstrated significant lower DFTs (9.7 +/- 3.8 joules) compared with a standardized unidirectional lead configuration (18.0 +/- 6.8 joules). It is concluded that: (1) there seems to be no significant difference in the DFT between simultaneous and sequential monophasic shocks; (2) biphasic waveforms require significantly less energy for defibrillation than their corresponding monophasic waveforms; and (3) the unipolar single-electrode defibrillation system is easy to implant and provides DFTs at energies comparable with epicardial lead systems.

Adolescent↗

PubMed1994

Heart rate during exercise: what is the optimal goal of rate adaptive pacemaker therapy?

The objective of minute ventilation (MV)-controlled pacemaker algorithms is to simulate the physiologic relationship of the sensed signal and the sinus node response during exercise. In our study we determined the relationship between heart rate and MV in healthy middle-aged subjects by measuring breath-by-breath gas exchange throughout peak exercise. Regarding several clinical limitations of peak exercise testing, we additionally evaluated whether a 35 W low-intensity treadmill exercise (LITE) protocol can be used as a substitute for peak exercise testing to determine the physiologic heart rate to MV slope. The results demonstrated that the heart rate to MV relationship is not linear throughout peak exercise but is curvilinear with a smooth logarithmic-type profile. To simulate this relationship, MV-based rate adaptive pacemakers should generate a decreasing heart rate to MV slope during higher levels of work. The heart rate to MV slope determined during the early, dynamic phase of low-intensity exercise represents the same slope derived from peak exercise below the anaerobic threshold. The low-intensity treadmill exercise protocol, with minimal patient effort, can thus be used as a substitute for peak exercise to optimize rate adaptive slope programming of MV-controlled pacemakers.

Algorithms↗

PubMed1994

Complications of pacemaker-defibrillator devices: diagnosis and management.

Treatment of resuscitated patients with implantable cardioverter defibrillators has become increasingly more common as a method for the prevention of sudden cardiac death. Major complications such as perioperative death (incidence 2% to 8%), infection (2% to 11%); and lead-related problems (3% to 27%) have been described in previous trials. In our experience with 140 patients, problems were related to leads (n = 11), the device (n = 2), pacing (n = 1), sensing (n = 13), and defibrillation function (n = 5). Additional problems that occurred during the perioperative period included infection (n = 11), hematoma, and seroma (n = 2). Thrombus formation along endocardial leads was observed in 13 of 62 (21%) patients. Different arrhythmias (n = 10), such as sinus tachycardia, atrial fibrillation, and nonsustained, slow or incessant ventricular tachycardia with shock delivery, were also detected. Surgical management (predominantly for the major problems) was used in 31 (48%) patients, drug treatment in 25 (39%), and reprogramming of the device in 24 (38%) patients. All of these problems can result in an increase in mortality rates. This article provides an overview of the complications of cardioverter defibrillator treatment and is based on both published data and our series.

Arrhythmias, Cardiac↗

PubMed1994

Predictors of outcome in patients with implantable transvenous cardioverter defibrillators.

The identification of patients who benefit most from implantable cardioverter defibrillator (ICD) therapy is of great interest. To find out if clinical variables, the signal-averaged electrocardiogram, and electrophysiologic study predict occurrence of appropriate ICD discharges and death, we followed-up on 76 patients after implantation of a transvenous ICD. During a mean follow-up period of 18.2 +/- 6.4 months, 29 patients (38.6%) experienced at least one appropriate episode. When these patients were compared with those who had either no therapy or inappropriate episodes, three variables were found to be significant in the identification of patients who experienced appropriate discharges: (1) The mean ejection fraction of patients who received appropriate discharges was 35.4% +/- 13.5% versus 45.1% +/- 15.3% in the other group (p < 0.05); (2) patients with appropriate therapy had sustained monomorphic ventricular tachycardia that was more likely to be inducible (75.9% vs 21.2%, p < 0.01); and (3) in patients with appropriate therapy ventricular fibrillation was less likely to be inducible (10.3% vs 25.5%, p < 0.05). The signal-averaged electrocardiograms were more often abnormal, but the differences were not significant. The total mortality rate in our patient group was 7.8%, with nonsudden cardiac death in four patients, noncardiac death in one patient, and sudden death in one patient. In our patient group a lower ejection fraction and inducible sustained monomorphic ventricular tachycardia were predictors of future ICD discharge after implantation. The survival rate after transvenous ICD implantation is excellent; a longer follow-up period is necessary to further define predictors of total mortality rate.

Cardiac Pacing, Artificial↗

PubMed1994

Intraoperative laser photocoagulation of ventricular tachycardia.

Mapping-guided laser photocoagulation was used as an intraoperative technique to treat ventricular tachycardia (VT) in patients with ischemic heart disease. Laser irradiation was delivered during VT to sites identified with local diastolic activation or, if VT was not inducible, to sites identified with delayed potentials during sinus rhythm. The group consisted of 12 male and two female patients who ranged in age from 41 to 74 years (mean, 59.9 years). All of the patients had experienced myocardial infarction before surgery; in eight cases myocardial infarction was associated with an anterior wall aneurysm, and in one case it was associated with a posterior wall aneurysm. Identified sites for laser irradiation were restricted to the endocardium in only four patients, whereas six patients showed endocardial and epicardial foci and four of them without circumscript aneurysm were subjected only to epicardial laser photocoagulation. Resection of an aneurysm was performed in nine patients, and additional bypass grafting (one to four grafts) has been performed in 10 patients. There were two perioperative deaths. Laser photocoagulation has proved to be an efficacious method for the surgical treatment of VT. It gives access to epicardial sites and, in particular, allows limited surgery in patients with restricted left ventricular function and no circumscript aneurysm.

Cardiopulmonary Bypass↗