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Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 469 records · Page 26Linked to original sources
PubMed1982

[Clinical-electrophysiological findings in patients following ventricular fibrillation].

30 patients, successfully resuscitated from ventricular fibrillation outside acute myocardial infarction, were studied by programmed right-ventricular stimulation. The stimulation studies were carried out one week up to 1.5 years after the event (median two months). Mean age of the patients was 50.2 +/- 8.8 years, 27 were male. The majority of patients had coronary heart disease and/or localized or diffuse ventricular contraction abnormalities. In 26 patients the stimulation protocol included the application of premature single and double ventricular stimuli during sinus rhythm and a paced ventricular rhythm at cycle lengths of 500, 430, 370 and 330 msec until ventricular tachycardia, ventricular flutter or ventricular fibrillation were induced. 4 patients were studied only at a cycle length of 500 msec. Using this stimulation protocol, in 7 patients (26.9%) sustained ventricular tachycardia, in 5 patients (19.2%) ventricular flutter and in 7 patients (26.9%) ventricular fibrillation were induced. These arrhythmias were induced at a basic cycle length of 500 ms in 10 patients, at 430 ms in 3 patients, at 370 ms in 4 patients and at 330 ms in 2 patients. In the remaining patients, only ventricular echo beats (one to six) of the intra-ventricular reentry type were induced. Thus these results show a persistent increase in ventricular vulnerability in a high percentage of patients (73%), provided that appropriate stimulation techniques are used. These observations may have great importance for the management of these patients.

Arrhythmias, Cardiac↗
PubMed1981

[Bundle of His extrasystoles as a cause for A-V block and junctional tachycardia (author's transl)].

The electrophysiological findings in two cases with premature beats arising from the bundle of His are presented. In the first case, the nonconducted impulses led to a functional first and second degree A-V block of the following sinus beats due to retrograde concealed conduction. In addition, very early premature beats from the bundle of His were conducted retrogradely to the atrium simulating blocked premature atrial beats. In the second patient, the premature beats appeared as bigeminy after each sinus beat. As the sinus beats and the extrasystoles from the bundle of His showed a left bundle branch block pattern, a ventricular tachycardia was suspected from the findings in the surface ECG. The reported cases demonstrate the clinical value of the His bundle electrography in patients with bradycardic and tachycardic rhythm disturbances.

Adult↗
PubMed1981

[Atrial arrhythmias after surgical repair of an atrial septal defect (secundum-type). Six years follow-up in adults (author's transl)].

Atrial arrhythmias before and after repair of an atrial septal defect (secundum-type) were analyzed in 100 patients. The mean postoperative follow-up was 5.8 years, the mean age at the last check-up was 33.4 years. Preoperatively, 10 patients showed atrial arrhythmias (6 pts atrial flutter or fibrillation [AF], 3 pts sinus node [SN] dysfunction, 1 pt atrial tachycardia). About 6 years after operation, 29 patients showed atrial arrhythmias (16 pts AF, 10 pts SN dysfunction, 3 pts atrial tachycardias). The 26 patients with AF and SN dysfunction were 10 years older and had a 3 years longer follow-up period postoperatively than those with sinus rhythm. In addition, they had a higher pulmonary artery pressure preoperatively. Especially the occurrence of AF after operation was strongly related to the age and the pulmonary artery pressure. All other factors had no significance. The data show that closure of an atrial septal defect cannot prevent the occurrence of AF in the following period. In addition, SN dysfunction is found postoperatively in a significant number of patients probably due to the intraoperative injury to the sinus node. However, it cannot be excluded that the unfavorable results may in part be due to the selection of the patients.

Adolescent↗
PubMed1981

[Non-invasive recording of late ventricular potentials--methodology and first clinical experiences (author's transl)].

Late potentials occurring after the QRS complex were searched for from the body surface using high-gain amplification and signal-averaging techniques with filter settings between 100 and 300 hz at a sampling rate of 10 khz. The number of repetitions of the averaging process ranged between 150 and 300. 52 patients were studied. In 11 control subjects, no late potentials were detected within the ST segment. Late potentials were observed in 3/27 patients without previously documented ventricular tachycardia, all having left ventricular aneurysms. All three patients had evidence of increased ventricular vulnerability (one dying from ventricular tachycardia, one with stimulus-inducible ventricular tachycardia, one with multiple episodes of ventricular fibrillation after surgery). In patients with previously documented ventricular tachycardia and/or fibrillation, late potentials occurred in 7/14 cases (50%), mainly in those with aneurysms (6/8 pts = 75%). Mean onset of late potentials after the QRS complex was 38 +/- 20.1 ms, mean amplitude was 3.9 +/- 2.0 uV, and mean duration was 17.1 +/- 5.4 ms. We conclude that late potentials, which represent late depolarization of a mass of ventricular tissue after slow conduction, herald increased susceptibility to ventricular tachycardia mainly in patients with ventricular aneurysms.

Adult↗
PubMed1981

[Prognostic significance of ventricular echo beats induced during programmed ventricular stimulation (author's transl)].

To determine the incidence and prognostic significance of the repetitive ventricular response, the present retrospective study was done in 123 patients (75 male, 48 female, mean age +/- S.D. 49 +/- 14 years) with a variety of cardiac rhythm disorders. Programmed right ventricular stimulation was done at a basic pacing rate of 120 b.p.m. using one (S2) and two (S2,S3) premature stimuli. The data were analysed as to the presence ro absence of a repetitive ventricular response and the outcome of the patients ((1) sudden death less than or equal to 1 h or documented ventricular fibrilllation without myocardial infaction without myocardial infarction; (2) survivors or patients dying from non-cardiac or non-suddenly). A repetitive ventricular response was observed in 45/123 patients (36.6%) after one and in 51/120 patients (42.5%) after two premature stimuli. It occurred in 9/9 patients with ventricular fibrilation and in 20/23 patients (87%) with ventricular tachycardia. Mean follow-up period was 84 +/- 37.1 weeks (+/- S.D.). Five patients were lost to follow-up. 17/123 patients were classified as sudden death patients, the remaining patients were regarded as surviving (or dying non-suddenly). After one premature stimulus, a repetitive ventricular response was observed in 34.9% of survivors and in 47.1% of non-survivors (n.s.). After two premature stimuli, the incidence of a repetitive ventricular response increased from 36.8% in survivors to 70.6% in non-survivors (p less than 0.005). 12/106 of patients (11.3%) surviving and 10/17 patients (58.8%) non-surviving had more than three ventricular echo beats (p less than 0.005). All patients non-surviving who demonstrated a repetitive ventricular response has intraventricular reentry. Depending on the regidity of the criteria used (i.e. number of echo beats), the sensitivity of the test ranged between 47 to 88%, whereas the specificity ranged between 44 to 94%. The number of false-positives was high (43 to 80%); however, the number of false-negatives was low (4 to 8%). Concluding, this retrospective study has shown a correlation between sudden death and the incidence and number of repetitive ventricular response (depending on the number of premature stimuli) and the type of reentrant beats (bundle branch reentry or intraventricular reentry).

Adult↗
PubMed1981

[Electrophysiological effects of the new antiarrhythmic drug flecainide (R 818) in man (author's transl)].

The electrophysiological effects of the new antiarrhythmic drug Flecainide (R 818) was tested in altogether 27 patients with and without disturbances of sinus node function and intraventricular conduction. Flecainide was given intravenously in a dose of 1 mg/kg and 2 mg/kg. Constant "therapeutic" plasma levels were reached by application of 1 mg/kg as a bolus and an additional infusion of 1 mg/kg during the test period of 20 min. The drug had no significant effects on sinus node function even in patients with sinus node dysfunction tested so far. Intracardiac conduction time was prolonged within all compartments of the heart in a dose-dependent manner. After bolus injection of 1 mg/kg, the HRA-A interval lengthened by 10.4%, the A-H interval by 13.5%, the H-V time by 15.7% and the V-RVA interval by 29.1% of the control value. In addition, the QRS complex widened by 8.1%. After 2 mg/kg Flecainide the HRA-A interval was prolonged by 9.0%, the A-H interval by 24.4%, the H-V time by 40.2%, and the V-RVA interval by 16.5% of the control value. The QRS complex widened by 24.2%. In contrast, there was only a small and often insignificant increase in the refractoriness of the different compartments of the heart (5-15% increase of the control value). In two patients with bundle branch block, a higher degree A-V block distal the H potential occurred after 2 mg/kg Flecainide. These electrophysiological effects may explain some antiarrhythmic actions of Flecainide. In addition, possible side effects of the drug can be assessed. In patients with intraventricular conduction defects the drug should be used with caution especially when given iv in higher doses.

Adult↗
PubMed1981

[Clinical-electrophysiological study of the effect of lorcainide on induction of ventricular tachycardia (author's transl)].

11 patients (mean age 52 +/- 16.3 years) with recurrent ventricular tachycardia (VT), in whom VT could be initiated by programmed ventricular stimulation, were studied before and after lorcainide, a new antiarrhythmic agent. Lorcainide was either injected intravenously at a dose of 2 mg/kg within five to ten minutes (n = 3) or infused at a rate of 0.1 mg/kg/min up to the same total dose. After intravenous administration, there was no change in inducibility of VT in three patients, whereas in seven patients VT was either more difficult to induce requiring two instead of one premature beat (n = 2) or a higher rate of basic pacing (n = 2) or VT was no longer inducible (n = 3). In one case, VT was easier to induce. In patients with still inducible VT, the rate of VT decreased from 220 +/- 33 b.p.m. to 186 +/- 49.1 b.p.m. (non-significant). The echo zone for initiation of VT did not show any consistent change. The coupling interval between the last stimulated complex and the first beat of VT increased from 327 +/- 66.8 ms to 390 +/- 98.6 ms (p less than 0.05). The effective refractory period of the right ventricle increased slightly though not significantly. In three cases paradoxical side effects, probably due to lorcainide, were observed. The blood level of lorcainide at the end of injection or infusion immediately before right ventricular stimulation was 0.69 +/- 0.48 micrograms/ml (range 0.11 to 1.74 micrograms/ml). No N-dealkylated metabolite of lorcainide was detected after intravenous injection. Thus far, lorcainide is effective in preventing initiation of VT in some patients making it more difficult to induce in others. However, long-term efficacy and tolerance to the drug cannot be predicted from the data of this study though the data suggest that the drug might be effective on the long-term run against ventricular tachyarrhythmias.

Benzeneacetamides↗
PubMed1980

Amiodarone.

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Amiodarone↗
PubMed1980

[Demonstration of retrograde block in a patient with preexcitation syndrome by intraoperative electrophysiological studies (author's transl)].

In a patient with a WPW syndrome, the electrophysiological investigation revealed a left-sided bypass conducting only in antegrade (A-V) direction. During right ventricular stimulation, there was a complete retrograde (V-A) block. Therefore no reentry tachycardia could be initiated. The patient was operated upon because of an aortic valve lesion. During operation the bypass was localized at the free wall of the mitral annulus by epicardial mapping. Even during direct stimulation at the ventricular insertion of the bypass, no retrograde conduction to the left atrium could be demonstrated. After ablation of the bypass by surgery, intra- and postoperative electrophysiological studies showed a normal antegrade activation pattern of the ventricles. The case reported demonstrates that the "heterodromia" of an accessory bypass can markedly influence the clinical setting in the WPW syndrome.

Action Potentials↗
PubMed1980

Further evidence for the site of reentry in so-called sinus node reentrant tachycardia in man.

To provide further evidence for the participation of the sinus node in so-called sinus node reentry in man, right atrial stimulation and endocardial mapping were performed in a case with sustained tachycardias which met the commonly accepted criteria for sinus node reentry. In addition to right atrial mapping, the activation of the high left atrium was depicted from the right pulmonary artery. The results clearly showed that in this patient the high right atrium was indeed the site of origin of the atrial echo beats which could be elicited by programmed premature atrial stimulation. The high left atrial electrogram (from the right pulmonary artery) was activated 35 msec after the high right atrium thus excluding the possibility of reentry in Bachmann's bundle. Atrial mapping during echo beats revealed a right atrial activation pattern which was similar to that observed during spontaneous sinus rhythm. Sinus node reentrant beats could also be evoked by programmed premature stimulation of the low lateral right atrium. In conclusion, activation of the high right atrium prior to the high left atrium is an important additional criterion for defining sinus node reentry in man. Thus, the recording of the left atrial signals from the right pulmonary artery helps to exclude reentry in the high left atrium, e.g. Bachmann's bundle.

Atrial Fibrillation↗