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Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 541 records · Page 30Linked to original sources
PubMed1975

[Sinus node automaticity and sinoatrial conduction].

In 64 patients so-called sino-atrial conduction time (SACT) was calculated by means of the extrastimulus technique. The normal value of this parameter was 82 plus or minus 18.7 ms (20 patients). Plotting SACT versus heart rate in all patients no correlation could be found. However, in 4 patients with spontaneous variations of the sinus cycle length a short SACT was calculated after long spontaneous intervals and vice verse. These results may indicate that SACT ist frequency-dependent. However, it is not clear whether the behaviour of the postextra-systolic pauses in these patients is due to changes of SACT or due to spontaneous variations of sinus node automaticity. The measurement of the first spontaneous interval (A3-A4) after the postextrasystolic pause revealed a prolongation of 30 ms (mean value) in comparison to the basic cycle length (A1-A1) after resetting the sinus node. If the stimulus was elicited late in diastole without premature depolarisation of the pacemaker cells, no significant difference between A3-A4 and A1-A1 intervals could be found. These results indicate that sinus node automaticity may be influenced by the premature stimulus. Therefore, the calculation of SACT is burdened by unresolved methodological problems.

Arrhythmias, Cardiac↗
PubMed1975

Adrenaline, noradrenaline, and adenosine 3',5'-monophosphate levels in plasma of healthy persons during ergometric work with and without beta-receptor blocking agents.

After endogeneous increase of noradrenaline and adrenaline during a submaximal exercise test, plasma levels of adenosine 3',5'-monophosphate (cyclic AMP) show no significant change. After effective beta-receptor blockade due to propranolol plasma levels of cyclie AMP do not change significantly, either during rest or during exericse. After effective beta-receptor blockade due to propranolol the plasma levels of noradrenaline and adrenaline, reached during exercise, are significantly reduced compared with the plasma catecholamine levels obtained under the same exercise conditions wtihout beta-blockade. In contrast to the findings of other investigators, increased plasma catecholamine levels after administration of propranolol could not be observed.

Blood Pressure↗
PubMed1975

[Accident during local anesthesia in a patient with antiarrhythmic therapy].

A side reaction of antiarrhythmic treatment in a 18-year-old patient with congestive cardiomyopathy is reported. During treatment with high doses of aprindine cerebral convulsions occurred. After ceasing the medication temporarily, a pacemaker revision was done in local anesthesia. Cerebral convulsions reappeared after injection of the local anesthetic. The patient died due to cardiac arrest. It is discussed that some amount of the local anesthetic agent (mepivacaine) was absorbed from the tissue elevating the blood level of local anesthetic drugs (aprindine and mepivacine) into the toxic range, thus producing cerebral convulsions, augmenting the stimulation threshold and depressing the automaticity of the heart. It is urged that antiarrhythmic treatment should be stopped before local anesthesia will be performed.

Adolescent↗
PubMed1975

Direct stimulation of the sinus node in man. A possible explanation for an unusual finding during premature atrial stimulation.

An atypical behavior of the postextrasystolic pauses was observed in a 19-yr-old patient studied by His bundle electrography and programmed premature atrial stimulation. In the normal case there is a prolongation of the postextrasystolic pauses compared to the spontaneous cycle length allowing calculation of sinoatrial conduction time (SACT). In this case there were constant postextrasystolic pauses during the whole range of prematurity which were identical to the spontaneous cycle length. It is suggested that the catheter tip was accidentally positioned at the sinus node itself. The lengths of the spontaneous cycles, of the return cycles, and of the postreturn cycles showed no significant differences. Thus, one may assume that sinus node automaticity was not influenced in this case.

Adult↗
PubMed1975

[The effect of drugs on "sino-atrial conduction time" and on sinus-node automaticity in man].

The effect of atropine, propafenone, and disopyramide on sinus node automaticity and "sino-atrial conduction" was tested in normal patients and patients with the sick sinus-syndrome. "Sino-atrial conduction time" was estimated indirectly by the extrastimulus technique. Atropine (n = 11) caused a significant increase in heart rate in all patients. The sinus node recovery time was shortened in 10 patients. "Sino-atrial conduction time" decreased on an average 35% (P less than 0.01). Three patients with a sick sinus-syndrome demonstrated a change of the pattern of the postextrasystolic pauses indicating great improvement in sino-atrial conduction. Propafenone (n = 10) led to a significant prolongation of the sinus node recovery time by 17% and of the "sino-atrial conduction time" by 27%. Disopyramide (n = 8) had no significant influence on heart rate and "sino-atrial conduction time". Sinus node recovery time was not changed in 6 patients. However, in two patients with a sick sinus-syndrome a dangerous prolongation of the sinus node recovery time after application of disopyramide occurred. The results indicate that atropine enhances sinus node function and sino-atrial conduction. On the other hand, propafenone and disopyramide exert either a depressant influence on sinus node automaticity or on sino-atrial conduction.

Atropine↗