PubMed Health⌕ Search

Biomedical subjects

H F Pitschner

Publications and source records attributed to H F Pitschner.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Implantable cardioverter/defibrillators with endocardial electrode systems: long-term stability of the defibrillator's effectiveness].

The vast majority of cardioverter/defibrillator implantations is performed with non-thoracotomy lead systems. The temporal stability of defibrillation energy requirements is well established for epicardial defibrillation lead systems, but not for non-thoracotomy lead systems. The defibrillation energy requirements were reevaluated in 30 patients, 13 months after implantation of a cardioverter/defibrillator with a non-thoracotomy lead system. The study patients group consisted of 4 females and 26 males; mean age 60.1 +/- 10.5 years; mean left ventricular ejection fraction was 32.2 +/- 6.2%. Coronary artery disease was the underlying heart disease in 12 patients, dilated cardiomyopathy in 15 patients, and artificial valve replacement in 3 patients. There was no clinical progression in the underlying heart disease between defibrillator implantation and control measurements; left ventricular ejection fraction was unchanged (32.2 +/- 6.2 vs. 32.3 +/- 6.4%); no changes occurred regarding patients' clinical status. In 27/30 patients the defibrillation threshold at defibrillator implantation could be reconfirmed at control measurements. The mean defibrillation energy/requirements at implantation (14.4 +/- 4.8 Joules) were unchanged compared to control measurements (14.8 +/- 4.6 Joules). A temporal stability of defibrillation energy requirements could be established for the monophasic (n = 15; 18.0 +/- 4 vs. 18.1 +/- 3.4 Joules) as well as for the biphasic waveform (n = 15; 11.1 +/- 3.4 vs. 11.5 +/- 2.9 Joules). The results of intraoperative defibrillation thresholds measurements are predictive for chronic defibrillation energy requirements in patients with non-thoracotomy lead systems.

Aged↗
PubMed1995

[Incidence of intervention-related heart valve lesions after high-frequency catheter ablation of the left-side accessory atrioventricular conduction pathways].

The aim of this study was to evaluate the incidence of valve lesions after radiofrequency catheter ablation of accessory atrioventricular pathways using the retrograde transaortic approach. Patients who presented no preexisting detectable valve lesion prior to catheter ablation and who underwent a comparable echocardiographic examination prior to and after catheter ablation were included for data analysis. From January 1991 until May 1993, 113 patients underwent radiofrequency catheter ablation of a left-sided accessory atrioventricular pathways at our institution. Fifty-nine patients were included in this study. Five patients (8.4%) developed new valve lesions after radiofrequency catheter ablation. There were two cases (3.3%) of aortic regurgitation and four cases (6.7%) of mitral regurgitation. In the majority of cases only mild valve regurgitation was detected. A hemodynamically significant valve lesion was observed in a single patient (1.6%). We speculate that the new onset of valve lesions is mostly due to catheter manipulations rather than due to tissue injury related to radiofrequency current application. Echocardiographic examinations prior to and after radiofrequency catheter ablation of accessory pathways may contribute to a further reduction in intervention-related complications.

Adult↗
PubMed1994

[The clinical significance of the ajmaline test in the noninvasive diagnosis of the Wolff-Parkinson-White syndrome].

A knowledge of electrophysiological parameters of accessory atrioventricular conduction pathways, such as effective refractory time and high conduction capacity in atrial fibrillation, make it possible to detect those patients who are at risk of life-threatening ventricular tachyarrhythmias. One criterion to identify these electrophysiological parameters is persistent pre-excitation after intravenous administration of ajmaline in Wolff-Parkinson-White (WPW) syndrome. Sensitivity and specificity of the ajmaline test in detecting patients at risk of life-threatening ventricular tachyarrhythmias were evaluated in 58 consecutive patients (22 females, 36 males; mean age 40.2 +/- 13 years) with the WPW syndrome. Pre-excitation was blocked after ajmaline in 43 patients (74%), pre-excitation persisting in 15 (26%). In 26 of the 43 patients with blocked pre-excitation the ajmaline test indicated short effective refractory time (< 270 ms) of the accessory pathway, and a high conduction capacity in 19 (minimal pre-excitation R-R interval during atrial fibrillation of < 250 ms). Sensitivity of the ajmaline test in the detection of a short refractory time was 33.3%, specificity 89.4%, while the corresponding values were 40.6% and 92.3% for the detection of accessory pathways with high conduction capacity in atrial fibrillation. These data show that the ajmaline test is not useful for estimating the electrophysiological characteristics of the accessory pathways. It is thus of only subordinate diagnostic value in predicting how much patients with the WPW syndrome are at risk of serious ventricular tachyarrhythmias.

Adult↗
PubMed1994

Effect of biphasic waveform pulse on endocardial defibrillation efficacy in humans.

Several clinical studies have proved increased defibrillation efficacy for implantable cardioverter defibrillators with biphasic pulse waveforms compared to monophasic pulse waveforms. This difference in defibrillation efficacy depends on the type of defibrillation lead system used. The influence of biphasic defibrillation pulse waveforms on the defibrillation efficacy of purely endocardial defibrillation lead systems has not yet been sufficiently examined, we, therefore studied 30 consecutive patients with drug refractory ventricular tachyarrhythmias during the implantation of a cardioverter defibrillator. After implanting an endocardial "integrated" sensing/defibrillation lead we performed a prospective randomized comparison of the defibrillation efficacy of monophasic and biphasic defibrillation waveform pulses. For endocardial defibrillation with the biphasic waveform the mean defibrillation threshold was 12.5 +/- 4.9 joules and for the monophasic waveform 22.2 +/- 5.6 joules (P < 0.0001). There was a decrease in the required defibrillation energy of biphasic defibrillation in 29/30 patients. Thus considering purely endocardial defibrillation a statistically significant and clinically relevant increase in defibrillation efficacy can be demonstrated for biphasic defibrillation waveform pulses.

Defibrillators, Implantable↗
PubMed1994

Radiofrequency catheter ablation of a concealed accessory atrioventricular pathway after heart transplantation.

Three months after orthotopic cardiac transplantation, a 46-year-old man developed paroxysmal supraventricular tachycardia. Electrophysiological investigation of the arrhythmia led to the diagnosis of an atrioventricular reentrant tachycardia involving a left lateral concealed accessory pathway. When antiarrhythmic drugs failed to suppress the arrhythmia, radiofrequency catheter ablation of the accessory pathway was performed without complication.

Atrioventricular Node↗
PubMed1994

[Subtypes of muscarinic receptors--aspects of their physiologic significance for controlling heart rate in the human].

The cDNAs for five different muscarinic cholinoceptors have been cloned. The biochemical and physiological relevance of the m1, m2 and m3 receptors is understood in many aspects. The pharmacological defined M1, M2 and M3 related to antagonists binding studies closely correspond with those cloned. We compared effects of atropine and of the subtype selective M-cholinoceptor antagonists pirenzepine and AF-DX 116 in humans. Dose- or time-response curves have been established for heart rate. Plasma samples were drawn in parallel with the effect measurements and analysed for drug concentrations. Subtype-selective radioceptor assays of the samples served to estimate the respective receptor occupancy in vivo. After low dosis of pirenzepine (M1-selective blockade) a negative chronotropic effect on heart rate could be observed. After high doses of pirenzepine or atropine (M-unselective blockade) the wellknown tachycardia appeared in parallel with occupancy of both the M2 and M3 subtypes. AF-DX 116 induced a tachycardia without a decrease of salivary flow in agreement with its selectivity profile (M2 > M1 > M3). Gastric emptying was only slightly inhibited by AF-DX 116 but nearly completely by a very high dose of pirenzepine blocking M1-, M2- and M3-cholinoceptors. The negative chronotropic effect on heart rate of a low dose of pirenzepine (M1 selective) was multi-folded by pretreatment with isoprenaline but disappeared during bicycle exercise. The implications of the functional M cholinoceptor heterogeneity in humans revealed by antagonists are discussed according to its possible importance for the control of autonomous nerve system.

Atropine↗
PubMed1994

[Indications and contraindications for therapy with implantable cardioverters/defibrillators].

Despite all advances in the diagnostic and therapy of cardiovascular diseases the mortality from malignant ventricular tachyarrhythmias is still a major health problem. In addition to established therapeutic strategies in the prevention of sudden cardiac death such as antiarrhythmic drug treatment, catheter ablation or antiarrhythmic surgery the implantable cardioverter/defibrillator was introduced to clinical practice in 1980. The number of 50,000 overall implants reflects the current clinical status of the therapy with implantable cardioverters/defibrillators. Significant technical improvements in the defibrillator therapy may contribute to an increase in therapy acceptance. These advances include the introduction of nonthoracotomy lead systems, enhanced defibrillation efficacy, full programmable devices providing tiered electrical therapy, improved diagnostic Holter functions and enhanced arrhythmia detection algorithms. The major present goals of defibrillator therapy are, detection and termination of malignant ventricular tachyarrhythmias, reduction of sudden cardiac death, reduction in patient's mortality and improvement in quality of life. The efficacy and safety of defibrillator therapy to prevent sudden arrhythmic death has been proven in several large clinical investigations. The annual sudden cardiac death mortality is < 2% even in high-risk patient populations. Compared to sudden cardiac death rate there is a much higher rate of overall cardiac mortality because a defibrillator is not able to prevent nonarrhythmic cardiovascular deaths. There is a clinical impression that cardiovascular mortality is lower in patients treated with an implantable cardioverter/defibrillator compared to patients treated with other therapies. However there are no results from controlled studies providing scientific evidence that defribillator therapy can reduce overall cardiovascular mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Contraindications↗
PubMed1993

123I-metaiodobenzylguanidine scintigraphy in the detection of irregular regional sympathetic innervation in long QT syndrome.

Twelve patients with the long QT syndrome were studied to determine the usefulness of 123I-metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPECT) at 2 h and 6 h after injection; the results were compared to 10 healthy volunteers (controls). Uptake of MIBG in the left ventricle at 2 h after injection was significantly reduced in patients with the long QT syndrome (1.43 +/- 0.13 vs 1.66 +/- 0.15 in controls, heart-to-mediastinum ratio, P < 0.002) and washout after 6 h was faster on a planar view image. Decreased MIBG uptake could be observed preferentially in the anterior and lateral walls near the apex. The half-time values of MIBG washout from the left ventricle were significantly reduced in the long QT syndrome (6.4 +/- 1.5 h) compared to controls (16.7 +/- 15.3 h, P < 0.002). In three cases, the same pattern of disturbed activity distribution was maintained even after surgical left cardiac sympathetic denervation. The present results strongly support the hypothesis that an inhomogenous regional distribution of sympathetic nerve terminals accompanied by an overall reduction in their absolute number may play an important role in the pathogenesis of the long QT syndrome. Additional functional disturbances, possibly related to the uptake of catecholamines in the left ventricle may coexist with regional inhomogeneity of nerve terminals. The differences observed from one case to the other may be related to the variation in severity of the disease. MIBG SPECT imaging seems an interesting new tool for the quantitative assessment of presynaptic sympathetic nerve terminal disturbances in the left ventricle of patients with the long QT syndrome.

3-Iodobenzylguanidine↗
PubMed1993

Intracardiac emergency defibrillation for refractory ventricular fibrillation during implantation of cardioverter defibrillators with nonthoracotomy lead systems.

Implantable cardioverter defibrillators (ICDs) are being implanted in increasing numbers. At intraoperative defibrillation threshold tests refractory ventricular fibrillation (VF) requiring emergency open chest resuscitation is a major concern during implantation of nonthoracotomy ICD lead systems. A new method of high energy endocardial/extrathoracic defibrillation via the implanted ICD transvenous defibrillation electrode (TDE) was used to terminate refractory VF. During implantation of ICD with TDE in 20 patients refractory VF occurred in two patients. The arrhythmia was terminated with endocardial/extrathoracic defibrillation in both cases, and no complications were observed.

Aged↗
PubMed1993

[Stored intracardiac electrograms: accuracy of arrhythmia classification in patients with cardioverter/defibrillator system].

A cardioverter/defibrillator that is capable of storing endocardial electrograms before and after electrical device therapy was implanted in 29 patients presenting drug refractory ventricular arrhythmias. During a follow-up period of 7.5 +/- 4.6 months 15/29 patients (51%) experienced a total number of 112 pulse generator discharges. In 104 arrhythmia episodes the stored electrogram was analyzed. Morphological criterias of the stored electrogram as detectable P-waves and changes in the QRS-morphology during tachycardia compared to sinus rhythm served for classification of the documented arrhythmia. The analysis of the stored electrogram established a definitive diagnosis of the arrhythmia and allows to distinguish supraventricular arrhythmias from ventricular arrhythmias in every episode. 72/104 (69.2%) of the discharges were classified as appropriate, 32/104 (30.8%) of the device discharges were not appropriate and caused by atrial fibrillation and flutter, sinustachycardia and AV-nodal reentrant tachycardia. In two patients device discharges caused by a sensing malfunction ot the pulse generator was detected by the analysis of the stored electrogram. The new diagnostic feature of stored electrogram shows a high accuracy of rhythm classification and represents a major advance in the treatment with cardioverter/defibrillators.

Aged↗
PubMed1993

[Transvenous ablation of recurrent ventricular tachycardia in arrhythmogenic right ventricular dysplasia].

Catheter ablation was used to cure refractory ventricular tachycardias (VT) in a 20-years old lady with arrhythmogenic right ventricular dysplasia. Antiarrhythmic drugs (procainamide, amiodarone, gilurytmal, flecainide and beta-blockers) used in monotherapy or combination didn't prevent recurrence of sustained VT. During electrophysiological study 3 different morphologies of tachycardia were induced, indicating multiple sites of arrhythmia. One of them was typical for right ventricular outflow tract and similar to the VT recorded in clinical conditions. Endocardial mapping in that region showed pathological low amplitude, fragmented potentials. They preceded by 35 ms the onset of QRS complexes during VT. This area was suggested as a presumed origin of the VT and chosen for transvenous ablation. 11 direct current shock of 200-250 joules (total energy 2400 j) were delivered. No complications were seen during and after ablation. The procedure was terminated when only non sustained VT can be induced by programmed stimulation. The same results were obtained during the control study one month later. However, the patient was taking sotalol and mexiletine. During 6 months period of ambulatory observation the patient was doing well, free of arrhythmias.

Adult↗
PubMed1993

[Cardioverter-defibrillator implantations without thoracotomy: clinical experience with various electrode configurations and defibrillation wave forms of an endocardial/subcutaneous defibrillator system].

Twenty-seven consecutive patients with refractory ventricular arrhythmias were investigated for implantation of an nonthoracotomy cardioverter-defibrillator lead system. Supply with a nonthoracotomy lead system could be achieved in 25 of 27 patients (92.5%), while implantation proved impossible in two patients due to elevated defibrillation thresholds. After implantation of an endocardial defibrillation electrode no differences were found compared to the implantation of an endocardial defibrillation electrode with a subcutaneous chest wall defibrillation patch with regard to the defibrillation thresholds obtained for monophasic defibrillation waveform. Supply with an endocardial defibrillation lead system was successful in 18 of 25 patients (72%). Ten consecutive patients with implantation of an endocardial defibrillation lead system alone were compared for defibrillation efficacy following monophasic and biphasic defibrillation waveforms. Defibrillation with biphasic waveforms led to a decrease in the necessary defibrillation energy from 19 J (4.6 J) to 10 J (4.0 J). There was occurrence of refractory ventricular fibrillation that could not be controlled by endocardial and transthoracic defibrillation in two patients during the intraoperative testing of defibrillation thresholds. In both cases these arrhythmias could be terminated by the described method of endocardial/extrathoracic defibrillation (200 J). Further perioperative complications were not observed. Over a mean follow-up of 6.8 (1-17) months all patients demonstrated regular functioning of the cardioverter-defibrillator. Dislocation of defibrillation electrodes did not occur. Implantation of a cardioverter-defibrillator can be performed without thoracotomy in the majority of cases. The use of defibrillator systems with biphasic waveform widens the scope for implantation of nonthoracotomy defibrillating lead systems.

Adult↗
PubMed1993

[Is the bradycardic effect of tedisamil at the expense of the loss of the inotropic effect? A pressure-volume analysis with the conductance (volume) catheter technique in patients with coronary artery disease].

UNLABELLED: To exclude or prove potential inotropic influences from tedisamil's bradycardiac effects, our hemodynamic evaluation in 13 patients (pat.) with coronary artery disease (CAD) included analyses of end-systolic pressure-volume relationships (ESPVR) after tedisamil, 0.3 mg/kg infusion at rest and during tachycardia induced by atrial pacing. Slope Emax [mm HG/ml] fell by 14% at rest (13 pat.) and by 10% during paced tachycardia (6/13 pat.) while loops of ESPVR tended to move rightward towards larger volumes (p > 0.05): all parameter changes indicated lack of significant inotropy loss with tedisamil. While mean heart rate decreased from 77.5 to 64.7 b/min and QTc duration increased by 14% (p < 0.05), filling pressure as well as dP/dtmin remained unchanged and vascular resistance rose by 30%. Parameters of LV-pump function (ejection fraction, stroke volume) decreased slightly (between 3 and 13%), while LV-volumes increased (end-diastolic by 6%, end-systolic by 23%). The respective parameter changes during paced tachycardia were comparable in tendency. CONCLUSION: Tedisamil's bradycardic effects are selectively generated without impairing either ventricular pump function or contractility in a clinically relevant fashion. Thus, tedisamil can be used safely in CAD.

Aged↗
PubMed1992

[Modification of atrio-ventricular conduction in treatment of supraventricular reentry tachycardia. (preliminary results)].

Intracardiac defibrillation to produce complete heart block is a modern and effective method for treatment of refractory supraventricular arrhythmias. The main drawback of this technique is the necessity of implantation of permanent pacemaker. There is however a growing interest in modification of atrio-ventricular (A-V) conduction to prevent arrhythmias without producing complete heart block. A new energy source used for this purpose is the radiofrequency (RF) current. Preliminary clinical results of modification of antegrade conduction in 5 patients with recurrent supraventricular arrhythmias are presented. HAT 100 (Dr Osypka GmbH, Germany) a high frequency generator was used for modification. Electrophysiological studies showed slow/fast type of junctional reentry tachycardia in 4 patients and paroxysmal atrial flutter with rapid ventricular response in 1. Since RF current produces much smaller and more discrete lesion, the precise localization of the active electrode was of primary importance. We manipulated the catheter, used for modification, in AV region until a relatively large atrial potential with only barely visible His bundle deflection was obtained. During reentry tachycardia the place of the earliest retrograde atrial depolarization was searched for. Current and voltage were monitored during the modification procedure. It was possible to titrate the HF energy to achieve the desired effect changing the power and the time of current application. The modification was repeated several times since PQ and AH interval increased > 50%. No prolongation of HV was noted. The modification was effective in all patients and allowed to avoid the induction of reentry despite the persistence of 1:1 AV conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

AF-DX 116, a cardioselective muscarinic antagonist in humans: pharmacodynamic and pharmacokinetic properties.

Effects of AF-DX 116, a cardioselective antagonist, on M cholinergic receptors (M-ChR) were studied in healthy volunteers. Occupancy of M-ChR subtypes by drug present in plasma samples (radioreceptor assay) was compared with these effects. After an intravenous dose of AF-DX 116 saturating greater than 90% of cardiac M2-ChR, an increase in heart rate by 25 beats/min was observed. This cardiac receptor occupancy and effect wore off with a parallel time course within 10 hours. No inhibition of salivary flow was observed, coinciding with a lack of M3-ChR blockade in the radioreceptor assay. Beta-adrenergic receptor blockade by propranolol did not affect either of the effects. No indication for active metabolites or stereoselective drug metabolism was found comparing HPLC and receptor assay for drug concentrations in plasma. We conclude that AF-DX 116 may be a useful drug for the treatment of bradycardia. Its lack of troublesome side effects is the result of its selectivity for cardiac M-ChR.

Adult↗
PubMed1991

[Continuous enoximone infusion in patients with severe heart failure in dilated cardiomyopathy, hemodynamic, neurohumoral, chemical laboratory and clinical results].

UNLABELLED: The hemodynamic, clinical, and neurohumeral effects of a prolonged (6-days) intravenous enoximone-infusion therapy were evaluated in 12 patients suffering from severe cardiac failure due to dilated cardiomyopathy. The loading dose of enoximone was 1.5 mg/kg. The maintenance dose during the two phases of constant intravenous infusion were 4 and 8 mcg/kg/min, respectively. The enoximone infusion therapy produced sustained salutary effects on cardiac hemodynamics and on clinical status in every patient. The enoximone infusion therapy caused a decrease in mean pulmonary artery pressure by 38%, an increase in cardiac index by 60%, the pulmonary and systemic vascular resistance decreased by 61% and 37%, respectively. Side effects and therapy-related cardiac arrhythmias were not observed. CONCLUSION: Enoximone infusion therapy provides sustained salutary hemodynamic and clinical effects in patients with severe cardiac failure.

Aldosterone↗
PubMed1989

AF-DX 116 discriminates heart from gland M2-cholinoceptors in man.

The M2-cholinoceptor subtype selective antagonist AF-DX 116 was compared with atropine with respect to effects on heart rate and salivary flow in healthy volunteers. These effects were related with in vitro occupancy of M-cholinoceptor subtypes in radioreceptor assays of plasma samples. Radioreceptor assays comprised M1-cholinoceptors in bovine cerebral cortex and M2-cholinoceptors in pig heart and rat salivary gland membranes. 3H-pirenzepine served as a label in the cerebral cortex 3H-N-methyl-scopolamine in the heart and gland preparations. Oral administration of 240 mg AF-DX 116 led to a time dependent increase in heart rate with a maximum effect comparable to atropine 40 micrograms/kg i.v. The effects of both drugs on heart rate were matched by a greater than 80% occupancy of heart M2-cholinoceptors in the radioreceptor assay of plasma samples. In contrast to the complete inhibition of salivary flow after atropine, AF-DX 116 induced an increase of salivation. The effects on salivary flow coincided with a greater than 80% occupancy of glandular M2-cholinoceptors after atropine but no detectable occupancy after AF-DX 116. Occupancy of the M1-subtype amounted to 61.7% after AF-DX 116 and a blockade of inhibitory, presynaptic M1-autoreceptors at missing postsynaptic blockade of glandular M2-cholinoceptors might explain the hypersalivation induced by AF-DX 116.

Adult↗