Search PubMed⌕ Search

Biomedical subjects

R Haberl

Publications and source records attributed to R Haberl.

104 records · Page 6Linked to original sources
PubMed1987

Frequency analysis of the surface electrocardiogram for recognition of acute rejection after orthotopic cardiac transplantation in man.

Recognition of acute rejection after heart transplantation has been based mainly on invasive methods until now. In this study we analyzed two well-defined surface electrocardiographic recordings by fast Fourier transform (FFT) (Blackman Harris window, 512 points) after low-noise, high-gain amplification (filter setting 0.5 to 300 Hz) each day for 4 weeks after cardiac transplantation in 27 patients. Twenty acute rejection crises requiring treatment were diagnosed by cytoimmunologic monitoring and endomyocardial biopsy. Single-beat analysis of the QRS complex by FFT revealed a progressive change of the spectral morphology (increase of the frequency content between 70 and 110 Hz) on the days of rejection in 19 of 20 patients. At that time there were no visible changes on the electrocardiogram in the time domain in most patients. At the same time, the frequency content of the ST segment decreased between 10 and 30 Hz in 16 of 20 patients. After successful treatment, the frequency spectra of the QRS complex and ST segment returned to control within 1 to 2 weeks in most patients. One false-positive result was seen in a patient with mediastinitis and large pericardial effusion. A drop in QRS amplitude (greater than 20%) occurred in 10 of 20 rejection crises and in 10 patients without rejection. Nine patients after cardiac transplantation without rejection and seven control patients after cardiac surgery (not transplantation) showed stable frequency plots from one day to the other after the first postoperative day, but with considerable changes in QRS amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Heart transplantation in therapy-resistant, recurrent ventricular tachycardias and ventricular fibrillation].

In life-threatening, drug resistant ventricular tachycardia (VT) or ventricular fibrillation (VF), orthotopic heart transplantation should be considered as an alternative to a directed surgical approach or to the implantation of an automatic defibrillator. We report on nine patients with primary VT or VF who underwent transplantation. These comprised eight men and one woman with a mean age of 35 years (range, 19-51 years); dilative cardiomyopathy was present in seven and coronary artery disease in two. Left ventricular ejection fraction was 19% (11-26%), arrhythmia was recurrent VF in five cases, recurrent VT in two, and recurrent VT/VF in two. Two patients died, one due to acute rejection, and the other 8 months postoperatively due to chronic rejection. The seven other patients are all asymptomatic and leading normal lives without arrhythmias or antiarrhythmic drug therapy. Based on our preliminary experience, some advantages and disadvantages of heart transplantation are discussed in comparison with other treatment modalities. Despite limited indications for orthotopic heart transplantation we feel that it should become the therapy of first choice in young patients with progressive, surgically incorrectable cardiac disease complicated by drug resistant VT or VF.

Adult↗
PubMed1986

Electrophysiologic and antiarrhythmic efficacy of oral sotalol for sustained ventricular tachyarrhythmias: evaluation by programmed stimulation and ambulatory electrocardiogram.

Programmed ventricular stimulation and ambulatory electrocardiography were performed both before and during oral sotalol therapy in 39 patients with ventricular tachyarrhythmia inducible by programmed stimulation (sustained ventricular tachycardia [n = 31], ventricular fibrillation [n = 3], nonsustained ventricular tachycardia [n = 5]). Oral sotalol was started at 80 mg twice daily and the dose thereafter was then gradually increased until a mean daily dose of 300 mg (range 160-480) was reached. In 12 of 34 patients with inducible sustained ventricular tachycardia or fibrillation the arrhythmia was suppressed; in 19 patients it was not and in 3 the spontaneous arrhythmia recurred. Reproducibly inducible nonsustained ventricular tachycardia was suppressed by sotalol in all five patients with this arrhythmia. Thus, a favorable electrophysiologic response was obtained in 17 (44%) of 39 patients. Arrhythmia suppression correlated with the type of arrhythmia (unsustained or sustained) induced during the control period (p less than 0.05), and nonresponders had a higher incidence of previously ineffective drug trials (p less than 0.05). In 22 patients treated long term with sotalol suppression of arrhythmia inducibility on programmed stimulation predicted freedom from recurrences (16 of 17), whereas continued inducibility indicated drug failure (5 of 5) (p less than 0.005). Serial ambulatory electrocardiograms performed in 37 of the 39 patients did not correlate with the results of electrophysiologic testing. For the patients on long-term treatment, invasive testing was superior to electrocardiographic monitoring in predicting outcome. These data indicate that in daily doses of 160 to 480 mg oral sotalol is a very useful agent in patients presenting with sustained ventricular tachycardia or fibrillation, and its efficacy is fairly well predicted by programmed stimulation.

Adult↗
PubMed1986

Ventricular preexcitation following catheter ablation of the His bundle in concealed WPW syndrome.

Catheter ablation of the His bundle is reported in a patient with drug-refractory supraventricular tachycardia meeting standard criteria of concealed WPW syndrome (conduction of the accessory atrioventricular pathway in retrograde direction only). After successful ablation of the His bundle, anterograde conduction along the accessory pathway, to our surprise, became apparent. During twelve months of follow-up, the patient was free of the tachycardia recurrences off antiarrhythmic drugs. While the clinical problem has been solved, the patient may--in case he should develop atrial fibrillation--present with rapid anterograde conduction via the accessory pathway. Based on this experience, better electrophysiologic protocols are needed to evaluate anterograde accessory pathway conduction properties in 'concealed' WPW syndrome, thus permitting one better to decide whether and which site of ablation should be chosen in drug-refractory cases.

Bundle of His↗
PubMed1986

Special control of infection and rejection episodes after four years of cardiac transplantation at the University of Munich.

During the past 4 years, 36 orthotopic heart transplantations and two heart-lung transplantations were performed at Munich University Hospital. Immunosuppressive regimen consisted of cyclosporine A and low dose prednisone. The rejection diagnosis was based on daily cyto-immunological monitoring (CIM) and high frequency electrocardiography. In addition, viral, bacterial, and fungal infections were examined by CIM. The CIM is based on an evaluation of activated lymphocytes, lymphoblasts, and lymphocyte subsets in the mononuclear concentrate isolated from the peripheral blood by Ficoll Hypaque separation. Of the 38 patients, 24 are currently alive from 1 month to 4 years later (including one heart-lung recipient 1.5 years postoperatively). Altogether, 40 rejection episodes occurred among the patients. The diagnosis was based on CIM (sensitivity = 95%) and on endomyocardial biopsies (sensitivity = 95%). Control of rejection therapy was also done by using these methods. When the biopsies showed ongoing acute rejection, additional antithymocyte globulin or antilymphocyte globulin therapy was administered, relative to the CIM results. When using the endomyocardial biopsies for rejection control only, results showed a very low rate of two to three biopsies per patient in the first 3 months postoperatively. In addition, 16 infection periods were detected: five viral, six bacterial, four fungal, and one case of toxoplasmosis. The CIM showed typical hints of these inflammations in 12 cases (sensitivity = 75%) before clinical signs were visible. This immediately led to further diagnostic examinations and specific anti-infectious therapies, which were initiated early.

Journal Article↗
PubMed1986

[Frequency analysis of the single beat electrocardiogram in the diagnosis of ventricular tachycardias].

High frequency components of the surface electrocardiogram have been found in patients with sustained ventricular tachycardia. However, evaluation of these signals has required signal averaging and highly sophisticated filter techniques. In order to overcome the limitations of averaging and apriori filtering, we performed a single beat analysis of the total and terminal QRS and ST-segment of surface electrocardiograms with fast Fourier transformation (512 points, Blackman-Harris window) after high gain, low noise amplification (0-300 Hz). Fourteen patients with previous myocardial infarction and spontaneous and electrically inducible sustained ventricular tachycardia, twelve patients with previous infarction but without clinical arrhythmias, and fifteen control subjects were studied. The frequency content of the terminal QRS, expressed as area under the spectral plot, was significantly lower in patients with ventricular tachycardia compared to patients without arrhythmias (p less than 0.01). The frequency content of the ST-segment in the range 10 to 40 Hz was higher in patients with ventricular tachycardia than in patients without arrhythmias and control subjects (p less than 0.01). The spectral representation at very low (0-10 Hz) and high frequencies (greater than 60 Hz) of the ST-segment and analysis of the total QRS did not allow separation of patients with ventricular tachycardia. Thus, spectral analysis of single beat electrocardiograms offers promise for the non-invasive identification of patients prone to sustained ventricular tachycardia due to coronary artery disease.

Aged↗
PubMed1985

Chronotropic action of alinidine on the isolated sinus node of the rabbit heart.

The main action of alinidine, proposed for the treatment of angina pectoris, is a reduction of heart rate. To evaluate this negative chronotropic action, we studied the effect of the drug (concentrations ranging from 0.57 to 29 X 10(-6) M) on sinus rate and pacemaker location by multiple intracellular impalements in 31 isolated rabbit right atria. Alinidine caused a dose-dependent prolongation of the spontaneous cycle length which amounted to 58 ms +/- 28 (13% +/- 7) (+/- 1 SD) compared with control at 2.9 microM. Corrected sinus node recovery time increased from 83 ms +/- 47 to 126 ms +/- 80. Higher concentrations did not further increase the cycle length. The bradycardiac action was due to a selective slowing of phase 4-depolarization of pacemaker fibres. Amplitude and duration of the transmembrane potential of dominant fibres remained unchanged. However, repolarization of latent and atrial fibres was prolonged. Atrial effective refractory period increased by about 10%. The electrophysiologic effects of clonidine in equimolar concentrations were similar to alinidine. This study identifies slowing of phase 4-depolarization of dominant fibres as cause of the negative chronotropic action of alinidine. Pacemaker location and sinoatrial conduction time were unaffected.

Action Potentials↗
PubMed1984

Comparison between intracellular and extracellular direct current recordings of sinus node activity for evaluation of sinoatrial conduction time.

For evaluation of sinoatrial conduction time in humans, study of extracellular direct current (DC) electrograms from the sinus node has been proposed. To validate this method, we compared transmembrane potentials from multiple sites (40 to 60, "mapping" of sinoatrial activation by microelectrode technique) and extracellular DC electrograms of the sinus node in 12 isolated rabbit atria. Sinoatrial conduction time, measured by microelectrodes and by extracellular electrograms, was essentially the same if the DC electrode was positioned over the pacemaker center (35 +/- 15 and 33 +/- 15 msec, respectively; deviation less or equal to 2 msec). While in all experiments phase 4 and phase 0 depolarization of dominant pacemaker fibers was reflected in the DC electrogram, it shape was influenced by pacemaker location and duration of sinoatrial impulse propagation. If sinoatrial conduction time was long (greater than 25 msec) the transition from the diastolic to the upstroke slope was smooth and the sinus node potential was clearly separated from atrial activity. If sinoatrial conduction time was short (less or equal to 25 msec) the onset of the upstroke slope was well defined and the upstroke slope directly merged into atrial activity. Extracellular recordings 0.2 mm away from the pacemaker center were fairly unchanged in shape; however, sinoatrial conduction time was significantly underestimated. Underestimation also occurred when the tip size of the extracellular electrode was increased from 0.2 to 0.5 and 1.0 mm. Thus sinus node activity is reflected in extracellular DC recordings; however, measurement of sinoatrial conduction time by this technique requires exact localization of the electrode over the pacemaker center, which cannot be controlled in humans.

Animals↗
PubMed1983

Acceleration of sinus rhythm during slow-rate atrial pacing.

We evaluated the effects of slow-rate atrial pacing on impulse formation of the sinus node in 13 isolated rabbit right atria using the microelectrode technique. After the spread of activation was mapped to determine true sinoatrial conduction time (SACT) (38 +/- 16 msec [+/- SD]), the atrium was paced for eight beats at constant intervals slightly shorter than spontaneous cycle length in steps of 10 msec. In all preparations, slow-rate atrial pacing failed to capture the pacemaker center, but shortened action potential duration because of electrotonic interaction between atrium and sinus node. The resulting acceleration of impulse formation of dominant fibers ceased instantaneously when atrial pacing was terminated. Estimation of SACT by constant pacing 5 beats/min faster than sinus rhythm seriously underestimated the true values (p less than 0.05), because sinus node acceleration prevented capture of dominant pacemaker fibers in 10 of 13 preparations. At pacing rates 10 beats/min faster than sinus rhythm, capture did not occur in eight of 13 experiments; at pacing rates 20 beats/min faster, the pacemaker center was captured in all preparations. This study describes sinus node acceleration as a consistent and hitherto unknown finding during slow-rate stimulation of the atrium. This phenomenon accounts for the failure of the constant atrial pacing technique to determine SACT accurately in man.

Action Potentials↗