PubMed Health⌕ Search

Biomedical subjects

B Lüderitz

Publications and source records attributed to B Lüderitz.

At least 433 records · Page 24Linked to original sources
PubMed1980

[Wolff-Parkinson-White syndrome: two accessory pathways concealed conduction accompanied by enhanced AV node conduction (author's transl)].

The case report of a 40 years old female patient with Wolff-Parkinson-White syndrome and concealed conduction of the accessory pathways is presented. Endocardial mapping revealed two re-entry tachycardias with different rates and different sequences of retrograde atrial depolarisation. These accessory bypass tracts were accompanied by enhanced AV node conduction. -- Patients with multiple accessory pathways and enhanced AV node conduction appear to be a special group of WPW-syndrome in respect of life-threatening tachycardias.

Action Potentials↗
PubMed1979

[Treatment of tachy-arrhythmias by implanted pacemaker (author's transl)].

A recently developed antitachycardic pacemaker was implanted into seven patients with drug-resistant tachycardias. The implantation was made after diagnosis of a tachy-arrhythmia by invasive techniques and after experimental determination of the effective site, optimal mode and effective frequency of stimulation, as well as the regulation and duration of impulse release. Thus the pacemakers were individually adapted to the particular arrhythmia. High-frequency stimulation and competitive stimulation were used as stimulation modes. The systems work automatically, triggered either by the ECG, the patient or externally. The frequency of attacks was significantly reduced in five patients, the duration of attacks in all.

Adams-Stokes Syndrome↗
PubMed1979

[Results of employing single crystal gammacamera and minicomputer in the first tracer passage to determine left-ventricular ejection fraction and wall motion (author's transl)].

Single crystal gammacamera and minicomputer were employed in 71 patients to determine left-ventricular ejection fraction (EF) (17 mCi 99mTc-HSA; 30 degrees RAO projection) by means of the first tracer passage. In 30 out of these patients, ventricular wall motion could be analyzed additionally because later on the gammacamera was equipped with a converging collimator. Comparison with cineventriculographically determined EF values revealed a good correlation (r = 0.91), not depending on left-ventricular wall motion pattern. Hereby, with first transit, high EFs were computed somewhat lower and low EFs were found somewhat higher. This non-limiting discrepancy is closely related to the influence of paracardiac "background"-radioactivity. Comparative analysis of segmental wall motion demonstrated agreement in 83% of the 90 segments examined. Therefore, it can be confirmed that performance of the first tracer passage for a evaluating segmental wall motion must not mandatorily be done with a multicrystal camera.

Adult↗
PubMed1978

[Lactacidosis in biguanide therapy: diagnosis and therapy. 4 cases compared to 179 cases in the world literature].

In 4 out of 9711 (= 1:2400) patients, lactice acidosis due to biguanides was diagnosed. Serum lactate concentration averaged 18.2 mmol/l and the pH value 6.87. All patients showed signs of renal insufficiency and three had congestive heart disease. In addition to treatment with biguanides, other factors might have contributed to the lactice acidosis in these patients: prolonged fasting, severe dehydration due to persistent vomiting, acute bronchopneumonia, and acute pyelonephritis. On addmission, two patients were in shock and all patients were semi-conscious or comatose. All patients were treated with bicarbonate and glucose/insulin. One patient was hemodialysed. Two of our four patients died. Oour four patients are compared with 179 patients in the literature with respect to mortality and prognosis of lactic acidosis due to biguanides.

Acidosis↗
PubMed1978

[Tachyarrhythmias (author's transl)].

Various types of supraventricular and ventricular tachyarrhythmias causing severe clinical symptoms may be refractory to coventional antiarrhythmic therapy. In a large number of cases, electrotherapeutical approaches such as DC-cardioversion and cardiac pacing are effective in controlling ectopic tachycardias. Electrical pacing offers certain advantages over standard DC-cardioversion for the termination of tachycardias: 1. No general anesthesia is required. 2. Digitalis induced arrhythmias may be abolished, a situation in which DC-cardioversion is dangerous and usually ineffective. 3. Pacing can be effected rapidly, simply and repeatedly leaving the pacing catheter in place. At the present time different modes of cardiac pacing techniques are in use in order to suppress supraventricular, junctional and ventricular tachycardias. These are: rapid atrial stimulation, overdrive pacing, coupled stimulation, patient initiated atrial pacing, precisely timed single or multiple premature stimulation, and programmed rate-related stimulation. Rate-related interval stimulation may be useful when applied in drug-resistant junctional and ventricular tachycardias or runs of ventricular extrasystoles as precursors of a tachycardia. DC-cardioversion as well as the pacing techniques proved to be low risk alternative methods for treatment of tachyarrhythmias unresponsive to drug therapy.

Cardiac Pacing, Artificial↗
PubMed1977

[Paralysis, organic brain syndrome, and cardiac dysrhythmias caused by chronic laxative abuse (author's transl)].

A 39-year-old woman developed generalised paralysis, reversible organic brain syndrome, and cardiac dysrhythmias after 15 years of laxative abuse. Under continuous and cautious administration of potassium the cardiac rhythm became normal within four days and two days later the paralysis and organic brain syndrome almost disappeared. The cause of the psychiatric symptoms is thought to be cerebral potassium deficiency and an abnormal sodium/potassium equilibrium. Other clinical signs and symptoms due to extreme potassium depletion are presented. The importance of Na+/K+-activated membrane ATP-ase in myocardium and CNS is discussed.

Adult↗
PubMed1977

Effects of antikaliuretic agents on cardiac electrophysiology--measurements in papillary heart muscle and in purkinje fibers.

Electrophysiological parameters of myocardial excitability of heart muscle in vitro were studied under the influence of antikaliuretic diuretics. Potassium canrenoate, amiloride and triamterene were added in final concentrations of 5-440 mug/ml incubation medium. Resting and action potentials as well as refractory periods of single muscle cells and Purkinje fibers were measured by the microelectrode technique.--The antikaliuretic substances potassium canrenoate, amiloride and triamterene led to a significant concentration-dependent prolongation of action potential duration and, correspondingly, to a lengthening of the refractory period. Glycoside-induced shortening of the refractory period could be demonstrated to be antagonized by triamterene.--Results suggest that aldosterone antagonists, amiloride and triamterene may exhibit antiarrhythmic properties in the ventricular myocardium as well as in the conducting tissue. Drugs are equally effective when compared in molar concentrations. The application of antikaliuretic diuretics seems to be useful in the therapy of congestive heart failure with respect to their extrarenal cardiac effects, too.

Action Potentials↗
PubMed1977

Sinoatrial pacemaker shift following atrial stimulation in man.

Indirect evidence of a sinoatrial pacemaker shift after programmed atrial stimulation in man is presented. Following electrically induced beats, time intervals and postextrasystolic morphology of atrial electrogram and P waves were scrutinized in 30 catheterization studies. Applying premature atrial stimulation, a decrease of the interval between the last basic atrial depolarization and the stimulus-produced atrial excitation (curtailed cycle) below a critical interval was followed by a sinoatrial pacemaker shift in three cases. This electrophysiologic event consisted of a concomitant change in shape of high right atrial electrogram and an increase of atrial cycle length. Simultaneous alteration of P waves could be detected in 2/3 patients. Assuming that the pacemaker shift indicates the arrival of ectopic activation in the sinus node, capture of the sinus node by the premature beat could be distinguished from failure to capture. Thus, pacemaker shift can be used for estimating sinoatrial conduction time in addition to present methods using measurement of postextrasystolic atrial intervals. The changes described could be seen both before and after atropine administration. Tracings of a pacemaker shift after cessation of rapid atrial pacing are also presented. In summary, we found a sinoatrial pacemaker shift underlying sinus node response to ectopic atrial activation in man, a phenomenon which contributes to our understanding of indirect assessment of sinoatrial conduction time by the premature stimulation technique.

Adult↗
PubMed1976

Effects of free fatty acids on electrophysiological properties of ventricular myocardium.

Several metabolic factors have been regarded as a cause of ventricular tachyarrhythmias in cardiac ischemia, i.e. hypoxia, acidosis, intracellular potassium loss, local catecholamine release as well as an increased catecholamine concentration and an evaluation of serum free fatty acids. The arrhythmogenic properties of anoxia and hypoxic acidosis, catecholamines as well as potassium depletion are well known. However, the relationship between elevated free fatty acids concentration and the occurrence of ventricular arrhythmias remain obscure. The micro-electrode technique was applied to examine the electrophysiological effects of free fatty acids in papillary heart muscle fibres. Both linoleate and palmitate cause a concentration-dependent decrease of action potential duration and a corresponding shortening of the functional refractory period in the presence of sufficient oxygen supply. The results suggest that a high concentration of free fatty acids may play an additional role in the genesis of ventricular tachyarrhythmias in cardiac ischemia.

Action Potentials↗