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Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 523 records · Page 29Linked to original sources
PubMed1976

His bundle recordings in a case of complete atrioventricular block combined with pre-excitation syndrome.

In a patient with complete A-V block suffering from attacks of dizziness an intermittent A-V conduction with a short P-R interval and a delta wave of the conducted ventricular complex were observed. After accelerating the sinus rate by atropine and by exercise, one-to-one conduction was established with QRS complexes of WPW type A configuration. His bundle recordings revealed a complete block within the normal conduction system at the level of the A-V node. A slow junctional rhythm with a normal H-V interval was activating the ventricle. During atrial pacing a one-to-one conduction through an accessory pathway could be documented at cycle lengths between 800 and 380 msec. sandwiched in between zones of complete block at smaller or longer cycle lengths. During ventricular stimulation no retrograde V-A conduction could be observed. The findings support the thesis of at least two functionally different A-V pathways in patients with pre-excitation syndrome.

Arrhythmias, Cardiac↗
PubMed1976

The effect of premature atrial depolarization on sinus node automaticity in man.

Sino-atrial conduction time (SACT) may be calculated from the difference between the length of the return cycle and the spontaneous cycle, using programmed premature atrial stimulation during spontaneous sinus rhythm. This approach to sinoatrial conduction assumes that sinus node automaticity is not changed by premature depolarization. In order to validate this assumption, we compared the length of the post-return cycles to the spontaneous cycle length in 71 patients. Patients were grouped according to clinical diagnosis and the value of calculated SACT. At long coupling intervals at which no reset of the sinus node occurred there was only a small prolongation of the post-return cycles (less than 8.4 msec, on an average) compared to the spontaneous cycle length. This suggests no or only an insignificant effect of premature depolarization on the sinus node. However, during test stimuli leading to reset of the sinus node, the post-return cycles were significantly prolonged between 20 to 30 msec, on an average. The response of the individual cases sometimes varied to a great extent. In patients who demonstrated a progressive linear prolongation of the return cycles at decremental shortening of the test interval, there was no significant prolongation of the post-return cycles versus the spontaneous cycle length. We conclude that 1) premature depolarization of the sinus node may have a depressant effect on sinus node automaticity, which, if present, is usually small; 2) calculation of SACT using the extrastimulus technique may overestimate true SACT.

Action Potentials↗
PubMed1976

[Cardiodepressive effect of alcohol in low doses in normal persons and patients with coronary disease].

To study the effect of small amounts of ethanol 1 ml whisky (43 vol. %) per kg body weight was given to normal subjects (n = 11) and patients with coronary heart disease (n = 11) and the systolic time intervals (STI) PEP (preejection period), LVET (left ventricular ejection time), QS2 (total electromechanical systole) and PEP/LVET were measured. A control group consisted of five patients with coronary heart disease. The following results were obtained: Already at rest PEP/LVET was significantly higher in patients with coronary heart disease. After the ingestion of alcohol, significant changes of the STI were observed; mainly an increase of PEP and PEP-LVET was found. In patients with coronary heart disease the effect began earlier, was significantly higher and lasted significantly longer than in normal subjects. According to invasive correlation-studies of different authors, these results indicate an impairment of left ventricular function, especially of ejection fraction and contractility. These alterations seem to be more pronounced in patients with coronary heart disease. The results of this study should be considered in advising patients with coronary heart disease.

Adult↗
PubMed1976

The effect of atropine on calculated sinoatrial conduction time in man.

This study investigates the effect of atropine on the length of the return cycles after premature atrial stimulation in man. On the assumption that sinus node automaticity is not changed by premature depolarization of the sinus node, sinoatrial conduction time (SACT) was calculated from the differences between the length of the return cycles and the spontaneous cycle length. 11 patients were studied before and after the injection of atropine. In all cases atropine caused an increase in heart rate. In 8 patients the return cycles exhibited a typical behavior. In 6 patients without signs of sinus node dysfunction, the mean calculated SACT was 109 msec, whereas 2 patients with a sick sinus syndrome (SSS) had a mean calculated SACT of 190 and 225 msec, respectively. 3 patients with SSS demonstrated an atypical pattern of the postextrasystolic pauses. In 6 patients without sinus node dysfunction, atropine caused a reduction of calculated SACT about 35%. In 2 patients with SSS the reduction was 38 and 49% of the control value, respectively, whereas in the remaining 3 patients with SSS who had an atypical return cycle pattern, a normalization occurred after the administration of atropine. We conclude that, besides its effects on sinus node automaticity, atropine has also a marked effect on sinoatrial conduction, even in patients with the sick sinus syndrome.

Arrhythmia, Sinus↗
PubMed1976

[Antiarrhythmic effect of disopyramide in ventricular extrasystole and auricular fibrillation].

Disopyramide (B 712) was tested in 39 patients with chronic arrhythmias of different kind: 23 cases with atrial fibrillation, 16 cases with ventricular ectopic beats, two cases with supraventricular tachycardias. The effect of disopyramide was compared to a pretreatment with one or several antiarrhythmic drugs (quinidine, beta-blocking agents, verapamil, ajmalin-bitartrat, aprindine, propafenone, diphenylhydantoin) which had been discontinued either due to ineffectiveness or the occurrence of intolerable side effects. Therapeutical effectiveness was controlled by on-line arrhythmia computers in the CCU or Holter monitoring. 15 patients were treated longer than 4 weeks up to 16 months (mean 35+/-22,6 weeks). The following results were achieved: 1 atrial fibrillation, abolition or significant reduction of the rate of recurrence in 10 out of 23 patients; slight reduction or no effect in 13 patients; 2. ventricular ectopic beats: abolition or significant reduction in 6 out of 16 patients, slight reduction or no effect in the remaining 10 patients. Patients who were treated successfully received the same dosis as those without therapeutical success. In cases with atrial fibrillation, the success was dependent on the duration of this arrhythmia prior to treatment. In comparison to the pretreatment with one or several of the above-mentioned anti-arrhythmic drugs, disopyramide was as effective as the drug given before. The analysis of the Ecg revealed a slight but insignificant prolongation of the time intervals. In 22 patients reversible dosage-dependent side effects were observed which are due to the vagolytic action of the drug: dry mouth, blurred vision, urinary hesitancy, nausea, headache. These side effects occurred at daily dosages between 400 to 800 mg increasing markedly in patients on 800 mg a day. The drug had to be discontinued in 4 cases because of side effects. During long-term treatment no severe side effects were observed. Thus, disopyramide may serve as an alternative to quinidine, especially if the latter has to be stopped because of side effects.

Adolescent↗
PubMed1975

[Diagnostic and prognostic value of endomyocardial biopsy in patients with congestive cardiomyopathy (author's transl)]rdiomyopathy(author.

Endomyocardial biopsies were obtained from the right ventricle in 25 patients with the clinical diagnosis of congestive cardiomyopathy. The biopsies were subjected to virological and histological studies (light and electronmicroscopy) and the findings correlated with clinical data. Abnormal morphological findings were present in all patients. The presumed clinical diagnosis was confirmed in 19, the morphological changes not being consistent with the clinical diagnosis of CCM in six patients. Electronmicroscopy revealed cardiac storage disease in one patient and pathological changes secondary to previous myocarditis in the other five. Clinical follow-up studies of the five patients apparently confirmed the morphological results, because in no case was there clinical deterioration, three patients in fact being in a fairly normal cardiac state at present. Using a morphological scoring system, the 19 patients with morphologically confirmed diagnosis of CCM were subdivided into two groupds, those with four points or less (group I, n equal to 9), and those with five pints or more (group II, n equal to 10). During a mean follow-up period of nearly 12 months the first group had a low mortality rate (n equal to 2), while the other had a high one (n equal to 6). The occurrence of signs of degeneration and mitochondrial alterations, in particular, was associated with a poor clinical prognosis. This differentiation into two groupds could not be achieved by clinical means alone. Type B3 Coxsackie virus was isolated from one biopsy, but no patient had significant serological evidence of virological infection.

Adult↗
PubMed1975

A new method for automated detection of the R-on-T phenomenon.

The detection of premature ectopic beats coinciding with the T-wave of the antecedent beat is important for patient monitoring. In the method described here, the difficulties of direct measurement of QT time are avoided by evaluating the changes of QT time according to heart rate by use of a diode function generator. An analog circuit is used for comparing the computed QT time with the coupling interval of successive beats. In case of a R-on-T-phenomenon an alarm is given. The frequency of alarms is registered on a trend recorder. The methods is based on empirical equations which all contain a constant factor. Our investigations showed that the variability of this factor during longer periods of monitoring was small enough to allow sufficient exactness of the evaluation procedure.

Adult↗
PubMed1975

[Diagnostic problems in the sinus node syndrome].

The sick sinus syndrome includes numerous arrhythmias due to various functional disorders of the sinus node, the atria and the A-V junctional tissue. These disturbances of impulse formation and conduction involve many diagnostic problems. If clinical methods as ECG monitoring are of no help, provocative tests are indicated. The best indirect test of the sinus node activity is the measurement of the sinus node recovery time after overdrive suppression. In addition, the sinu-atrial conduction time, the conduction velocity within the right atrium, the A-V node and the His-Purkinje system can be measured. In patients with the sick sinus syndrome abnormalities of conduction in the specialized cardiac tissue are common in addition to sinus node dysfunction. The results of the provocative tests are important for drug therapy or pacemaker implantation.

Arrhythmias, Cardiac↗
PubMed1975

[Pathogenesis of acquired coronary anomalies. Case report].

The heart of a 44 years old man who died of a severe calcifying endocarditis of the aortic valves and the aortic root demonstrated a rare anomaly of the coronary arteries. The ostium and the stem of the left coronary artery were missing. In the left aortic sinus there was a small dimple covered by calcified tissue. Using histological serial sections a small vessel was detected that was completely obliterated by organized thrombotic tissue running between the small dimple in the aortic sinus and the main branches of the left coronary artery. This vessel was supposed to be the remaining stem of the left coronary artery. The regular branches of the left coronary artery were supplied by an anastomosis between the proximal part of the right coronary artery and the descending branch of the left coronary artery running within the upper interventricular septum. It has been suggested that this rare anomaly was caused by a gradual obliteration of the ostium and the stem of the left coronary artery during the course of the calcifying rheumatic endocarditis of the aortic valves.

Adult↗
PubMed1975

[Electrophysiological effects of the antiarrhythmia agents disopyramide and propafenone on human heart conduction system].

The effect of Disopyramide and Propafenone on intracardiac conduction and refractory periods was tested by means of His bundle electrography and atrial stimulation. Disopyramide (1,7 mg/kg) was administered in 10 patients. There was no significant change of heart rate and conduction time within the atrium and the AV-node. The conduction velocity within the His-Purkinje system was significantly slowed by 13% of the control value. The ERP of the atrium as well as the ERP and FRP of the AV node were prolonged. Propafenone (1,7 mg/kg) was tested in 18 patients. The heart rate was significantly slowed by 13% of the control value. The conduction velocity within all compartments of the heart was depressed uniformly. The all-over-all prolongation of the HBE-intervals was 15%. Furthermore the results are in favour of a prolongation of the ERP of the atrium and the ERP of the AV node. The results can only partially explain the antiarrhythmic effect of the drugs. However, the data are important for assessing the possible side effects during antiarrhythmic treatment especially in patients with disease of the conduction system.

Adult↗