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Biomedical subjects

B Lüderitz

Publications and source records attributed to B Lüderitz.

At least 379 records · Page 21Linked to original sources
PubMed1986

Combination of antitachycardia pacemaker and automatic implantable cardioverter/defibrillator for ventricular tachycardia.

Antitachycardia pacing for ventricular tachycardia (VT) is associated with the possibility of fibrillating the heart; on the other hand, the frequency of VT and patient discomfort can limit treatment with the automatic implantable cardioverter/defibrillator (AICD). To contribute to the further development of a universal pacemaker, we evaluated the combined use of the antitachycardia pacemaker ("tachylog") and the AICD in five patients with recurrent VT. In the automatic mode, the "tachylog" worked as a bipolar VVI pacemaker. For antitachycardia pacing, a burst of rapid ventricular pacing was delivered at about 80% of the cycle length. During a follow-up period of 5 +/- 2 months (range, 3 to 8) two to 291 successful interventions of antitachycardia pacing were counted from diagnostic data which had been collected by the pulse generator during the course of treatment. When the antitachycardia pacemaker failed to terminate VT, the AICD was activated. In the individual case, between 0 and 41 discharges of the AICD were delivered. The high pulse energy of the AICD did not damage the antitachycardia pacemaker; no interference of the two devices was observed. Future antitachycardia systems should be more flexible with regard to detection and termination modes, combining antitachycardia pacing with back-up defibrillation.

Aged↗
PubMed1986

Automatic implantable cardioverter/defibrillator (AICD) and antitachycardia pacemaker (Tachylog): combined use in ventricular tachyarrhythmias.

UNLABELLED: Antitachycardia pacing in ventricular tachyarrhythmias (VT) is associated with potential acceleration of VT; frequency of VT and discomfort of the patient (pt) can limit treatment with the AICD. We therefore evaluated the combined use of antitachycardia pacing and AICD in 6 of 14 patients (age 50-70, mean 60 years) with AICD implantation because of VT, which could be terminated by temporary overdrive pacing. With the interactive mode of the Tachylog, termination of VT by the pacemaker as well as by the AICD was assessed after implantation. In the automatic mode, the Tachylog functioned as a bipolar VVI device with antitachycardia burst stimulation: 2-5 stimuli, interval 260-300 ms, 1-2 interventions. During follow-up of 12 +/- 5 months, the Tachylog terminated VT reliably 20 to 327 times per patient. In three patients, burst stimulation accelerated VT, which was terminated then by the AICD discharge. CONCLUSION: Drug resistant ventricular tachyarrhythmias can be terminated by the Tachylog pacemaker avoiding patients' discomfort. In case of acceleration, ventricular tachyarrhythmias can be controlled by the automatic implantable cardioverter/defibrillator. A universal pacemaker should combine antitachycardia pacing with back-up defibrillation mode.

Aged↗
PubMed1986

[Spectrum of effects of beta receptor blockade in cardiac arrhythmias].

The efficacy of beta adrenergic blocking agents has been observed in the treatment of a variety of cardiac arrhythmias. Electrophysiological experiments demonstrated that beta receptor blocking drugs prevent catecholamine-induced alterations of the transmembrane action potential. Clinically used beta blocking agents are effective in preventing arrhythmias provoked by sympathetic stimulation such as sinus tachycardia, paroxysmal junctional tachycardia, atrial, nodal, and ventricular premature contractions. Beta receptor blocking drugs are especially useful in tachycardias based on hyperkinetic heart syndrome and in exercise-induced premature beats in patients suffering from coronary heart disease. Beta blocking agents are--at least in our hands--most useful in combination with class I antiarrhythmic drugs with the intention to reduce the dosage--i.e. the side effects--of various antiarrhythmic drugs. In hyperthyroidism beta adrenergic blocking agents are effective complementary to the specific treatment. In cases of intoxication with beta blocking drugs complicated by myocardial depression and severe bradycardia glucagon must be regarded as a very useful compound.

Adrenergic beta-Antagonists↗
PubMed1986

[Historical development of the cardiac pacemaker].

The history of electric cardiac stimulation is long and fascinating. It is not only the anatomy of the heart, but also the analysis of the peripheral pulse that plays an important role in the history of cardiac pacing. The Romans, the Greeks and even before them the Chinese attempted to explain the origin and variations of the pulse as the basis of further investigations. - The growing clinical importance has been recognized and renewed as Zoll in 1952 described a successful resuscitation in cardiac standstill by external stimulation. Meanwhile more than 3 million patients with disorders of cardiac rhythm have been treated all over the world in the last 25 years. Recently the technical refinements of intracardiac stimulation and defibrillation improved our knowledge of cardiac physiology and diseases, and arrhythmias in particular. The pertinent interest in these dramatic developments and the intention to learn more about the basic fundamentals are reasons to look at the history of cardiac pacing. The advances in the field of therapeutic and diagnostic application of cardiac pacing will continue as rapidly as before in order to give us further significant aid in taking care of the patient.

Cardiac Pacing, Artificial↗
PubMed1986

[A rare pacemaker complication of a perforation by a ventricular screw electrode causing hemothorax].

The myocardial perforation of a pacemaker electrode is an extremely rare complication associated with the danger of cardiac tamponade. We report on a perforation of a ventricular screw-in electrode with migration through the pericardium and bleeding in the left thoracic cavity. Two-dimensional echocardiography in combination with clinical, electrocardiographic and X-ray examination permits a reliable non-invasive diagnosis.

Aged↗
PubMed1986

[Antitachycardia pacing therapy in supraventricular tachycardia using the microcomputer-guided Tachylog 651 pacemaker].

Microprocessor-controlled antitachycardia pacemaker expand the automatic detection of the tachycardia and incorporate multiple, different termination modes. We report our results in the long-term therapy of paroxysmal supraventricular tachycardia with the antitachycardia pacemaker "Tachylog 651". The system was implanted in 10 patients with a mean age of 48 years (from 20 to 68 years): Wolff-Parkinson-White syndrome 4 patients, paroxysmal AV nodal reentrant tachycardia 6 cases. The rate of the reentrant tachycardia was 162 +/- 23/min. The system reliably differentiated between paroxysmal supraventricular tachycardia and sinus tachycardia, including 4 patients with a tachycardia rate of less than 150/min. Burst overdrive pacing was effective in 6 patients and the "self-search system" in 3 patients. During follow-up of 9 +/- 4 months 104 +/- 93 successful interventions per patient were observed; change of the termination mode became necessary in 4 patients and of the detection mode in 3 patients. The incorporation of programmable detection and multiple termination modes in the microprocessor-controlled antitachycardia systems allows the effective long-term antitachycardia pacing. The multiprogrammable "Tachylog 651" pacemaker is an advancement in the electrotherapeutic treatment of paroxysmal supraventricular tachycardias, including the automatic treatment of tachycardias with low rates.

Adult↗
PubMed1986

[Electrophysiologic effects of diprafenone in supraventricular and ventricular tachycardia].

The electrophysiologic effects of diprafenone were evaluated in 31 patients (9 X AV nodal reentrant tachycardia, 9 X Wolff-Parkinson-White syndrome, 4 X paroxysmal atrial fibrillation, 10 X recurrent ventricular tachycardia). Electrophysiologic studies were performed before and after intravenous infusion of 1.5 mg/kg body weight diprafenone in a period of 10 minutes. Diprafenone prolonged the mean RR interval during sinus rhythm from 690 +/- 109 ms to 789 +/- 93 ms and the maximal sinus node recovery time from 1081 +/- 216 ms to 1300 +/- 398 ms (p less than 0.001). The effective refractory period of the right atrium increased from 195 +/- 22 ms to 210 +/- 28 ms (p less than 0.01) and of the right ventricle from 220 +/- 20 ms to 235 +/- 20 ms (p less than 0.001). Diprafenone produced a prolongation of the antegrade effective refractory period of the AV node from 260 +/- 35 ms to 294 +/- 39 ms (p less than 0.01) and of the retrograde effective refractory period from 265 +/- 76 ms to 400 +/- 130 ms (p less than 0.001). The effective refractory periods of the Kent bundle increased: antegrade from 299 +/- 45 ms to 413 +/- 133 ms, retrograde from 252 +/- 33 ms to 286 +/- 169 ms (p less than 0.05). Suppression of inducibility was observed in 12 of 17 patients with supraventricular reentrant tachycardia, in 5 of 8 patients with atrial fibrillation and in 7 of 10 patients with recurrent ventricular tachycardia. The rate of supraventricular tachycardias decreased under the influence of the substance.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1985

Usefulness of programmed stimulation in predicting efficacy of propafenone in long-term antiarrhythmic therapy for paroxysmal supraventricular tachycardia.

The electrophysiologic effects of intravenous (i.v.) and oral propafenone were evaluated in 14 patients with Wolff-Parkinson-White syndrome and in 10 patients with atrioventricular (AV) nodal reentrant tachycardia. The effective refractory periods of the right atrium and the AV node increased after both preparations. In patients with Wolff-Parkinson-White syndrome, i.v. propafenone blocked anterograde accessory pathway conduction in 2 patients and retrograde conduction in 1; during oral therapy, accessory pathway conduction block occurred in 2 additional patients. The mean cycle length of the supraventricular tachycardia (SVT) increased from 338 +/- 60 ms to 387 +/- 56 ms (p less than 0.05) after i.v. application, and from 336 +/- 65 ms to 367 +/- 65 ms (p less than 0.05) during oral propafenone. The shortest pacing interval maintaining a 1:1 AV conduction increased from 325 +/- 65 ms to 368 +/- 81 ms (p less than 0.05) after i.v. infusion, and from 333 +/- 57 ms to 369 +/- 75 ms (p less than 0.05) during oral therapy. There was no difference in the electrophysiologic effects between i.v. and oral propafenone. The induction of SVT was prevented by i.v. propafenone in 10 of 20 patients and in 4 additional patients with oral propafenone. During follow-up, 6 of 7 patients, whose SVT could not be initiated by electrophysiologic drug testing, remained free from recurrences, whereas 5 of 7 patients with inducible tachycardia had recurrences of SVT. Thus, in patients with SVT, propafenone prolonged accessory pathway and AV nodal conduction and had a beneficial effect on circus movement tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

[Functional disorders of chamber demand (VVI) and sequential AV (DDD) pacemakers caused by muscle potentials].

Muscle potentials as a cause of pacemaker malfunction are often unrecognized, because control examinations are usually performed without physical exercise. Two observations are cited to illustrate how malfunctioning of different modes of stimulation can be caused by interference from muscle potentials. In addition to the known suppression of impulse production, fixed-rate stimulation may occur. These observations indicate that pacemaker function should be tested also during physical activity. Any malfunction can almost always be stopped by re-programming amplifier sensitivity.

Action Potentials↗
PubMed1985

[Supraventricular tachycardia: the results of bundle of His ablation].

Transvenous electrical ablation of AV conduction was performed in 15 patients with drug-resistant supraventricular tachycardia. Eight patients had paroxysmal AV nodal reentry tachycardia, one had permanent junctional reentry tachycardia, five had recurrent atrial flutter and one paroxysmal atrial tachycardia. The intracardiac ablation was done with 150-350 J, on average twice per patient. Permanent 3 degrees AV block was achieved in ten patients, in none of whom there was a recurrence of the tachycardia. In four patients with re-established AV conduction the clinical symptoms had nonetheless improved; despite repeated use of His-bundle ablation, permanent junctional reentry tachycardia could not be controlled satisfactorily and required surgical section of the accessory pathway. Apart from septic fever in one patient there were no serious complications. Implantation of a pacemaker, however, was required in all those patients in whom a permanent 3 degrees AV block had been produced. For this reason alone, His-bundle ablation should only be used in drug-refractory supraventricular tachycardias. But in these this method presents an important advance in treatment.

Adolescent↗
PubMed1985

[Localization of pre-excitation in the WPW syndrome by analysis of the ventricular contraction course].

Fourier phase analysis of gated radionuclide ventriculography (RNV) was applied in 23 patient for the identification of cardiac contraction patterns in WPW syndrome (controls with normal ventricular function and sinus rhythm, n = 30). The sequence and velocity of regional ventricular wall motion was determined and correlated to the results of electrophysiological studies. In 3/23 patients the contraction pattern was not different from controls. Indicating the preexcitation in 20/23 patients the earliest ventricular contraction was localized as follows: right atrial n = 5, paraseptal right n = 2, paraseptal left n = 6 and atrial left n = 7. In 15/16 patients nuclear data corresponded with electrophysiological endocardial mapping. Phase analysis of RNV provides a reliable non-invasive method for localization of preexcitation in WPW syndrome.

Electrocardiography↗
PubMed1985

[Automatic and semiautomatic contour finding of the left ventricle in the 2 dimensional echocardiogram. In vitro studies in formalin-fixed swine hearts].

In order to test semiautomatic and automatic contour finding procedures in 2-dimensional echocardiograms we determined endocardial borders in 42 short-axis slices of post-mortem animal hearts after interactive image enhancement such as scaling, normalisation and linearisation of grey levels semiautomatically and automatically by a complex contour finding algorithm. The areas calculated on the basis of these semiautomatic and automatic procedures were compared with "true" anatomic areas derived from planimetry. The complex computer algorithm is based on the detection and analysis of grey level gradients. The algorithm first creates a raw contour which still contains intra- and extracavitary artefacts as well as interrupted endocardial strings. Using a statistical iterative classification procedure and a least-square polynomial approximation the endocardial strings were structured, completed and smoothed and the artefacts eliminated. We were able to determine endocardial contours by semiautomatic methods in 33 (79%) and by automatic procedures in 30 (73%) of the echocardiograms. The correlation between semiautomatic and "true" contours was r = 0.97; y = 1.01x-0.46; standard error of the estimate (SEE) 0.51 cm2, between automatic and "true" contours r = 0.98; y = 0.99x - 0.31; SEE 0.43 cm2; the correlation parameters between the anatomic "true" areas and the areas calculated on the basis of manually derived borders were r = 0.98; y = 0.97x - 0.05; SEE 0.45 cm2. From our studies we conclude that left ventricular endocardium in short axis slices of postmortem animal hearts could reliably and reproducibly be detected by semiautomatic as well as by automatic procedures using a contour finding algorithm.

Animals↗
PubMed1985

[Modification of myocardial function parameters by L- and D-penbutolol--an echocardiography, placebo-controlled double-blind study].

In order to study left ventricular contraction parameters of L-penbutolol and D-penbutolol (isopenbutolol) we evaluated TM-echocardiograms of 12 healthy volunteers at 30 and 60 minute intervals for 8 hours after oral administration of 40 mg L- and D-penbutolol and placebo. Three different observers determined end-systolic and end-diastolic dimensions, left ventricular shortening fraction (SF) as well as mean-, peak- and rate corrected circumferential fiber shortening (VCF) and calculated at each measuring point the difference from the control value (Delta). L-penbutolol demonstrated a typical beta-blocking effect with a significant (p less than 0.001) decrease of systolic (11.1 +/- 8.6 mm Hg) and diastolic blood pressure (6.7 +/- 4.6 mm Hg) and heart rate (10.0 +/- 7.4 bpm) as well as a significant (p less than 0.001) negative inotropic effect expressed by a decrease of SF (6.5 +/- 4.2%) and VCF-mean (0.40 +/- 0.15 circ/s), VCF-peak (1.04 +/- 0.61 circ/s) and rate corrected VCF (0.28 +/- 0.08 circ/s). However, we saw a similar but less distinct negative inotropic and chronotropic effect of D-penbutolol as compared to placebo. HR decreased by 5.3 +/- 6.2 bpm (p less than 0.001), SF decreased maximally by 5.0 +/- 3.2% (p less than 0.05), VCF-mean by 0.27 +/- 0.08 circ/s (p less than 0.001), VCF-peak by 0.71 +/- 0.31 circ/s (p less than 0.001) and rate corrected VCF by 0.22 +/- 0.04 circ/s (p less than 0.001). By means of TM echocardiography it was therefore possible to document a strong beta-blocking effect of L-penbutolol as well as a negative inotropic and negative chronotropic effect by the D-isomer of penbutolol.

Adult↗
PubMed1985

[Automatic contour detection in the 2-dimensional echocardiogram--studies in a general patient population].

In order to test the application of an endocardial contour finding algorithm in apical projections we examined 56 consecutive patients by 2-D echocardiography. According to the quality of the endocardial definition we graded the total patient population in 4 qualities, grade I being the best and grade IV being the worst echocardiographic image with multiple extracavitary and intracavitary artefacts. Following manual and automatic detection of LV endocardium in end-systole and end-diastole by 2 observers we calculated LV areas (cm2), volumes (ml), ejection fraction (%) and regional wall motion (% radial shortening and % area shrinkage) and determined the reproducibility of the two different endocardial definitions. In all echocardiograms with good endocardial visualisation (grade I and II; n = 31, 55%), in 9 out of 15 patients with grade III and 4 out of 10 patients with grade IV echocardiograms we could successfully apply the contour finding algorithm. The comparison between automatically and manually detected contours showed good correlations with small standard errors; however the reproducibility of data expressed by the interobserver variability (V) calculated on the basis of automatically found contours was significantly better as compared to the manually derived contours. (V manual contour = 4.8-8.5 versus automatic contours 0.63-0.68). The systolic volumes (manual versus auto) correlated with r = 0.93, SEE 8.3 ml; the end-diastolic volumes (manual versus auto) with r = 0.90, SEE 11.3 ml, the ejection fraction (manual versus auto) with r = 0.93, SEE 5.1%. The determination of regional LV wall motion demonstrated an agreement in 91% and a discrepancy in 9% of regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗
PubMed1985

[Sotalol in supraventricular tachycardia. Electrophysiologic measurements in Wolff-Parkinson-White syndrome and AV node re-entry tachycardia].

The electrophysiologic effects of sotalol were studied in 11 patients with Wolff-Parkinson-White syndrome and 9 patients with AV nodal reentrant tachycardia. Electrophysiologic studies were performed before and after intravenous infusion of 80 mg sotalol over a period of 5 minutes. Sotalol prolonged the effective refractory period of the right atrium and the right ventricle. Both AV node and accessory pathway conduction were depressed by sotalol in antegrade and retrograde directions. Induction of reentrant tachycardia was prevented in 6 of 18 patients. The rate of reentrant tachycardia decreased from 182 +/- 29/min to 153 +/- 14/min (p less than 0.01) and the ventricular rate during atrial fibrillation from 148 +/- 14/min to 112 +/- 12/min (p less than 0.05). Sotalol exhibited a depressant effect on all parts of the reentrant circuit: atrium, ventricle, AV node, and accessory pathway. Thus, sotalol is effective in the therapy of patients with recurrent supraventricular tachycardias.

Adult↗