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Biomedical subjects

N Edvardsson

Publications and source records attributed to N Edvardsson.

68 records · Page 4Linked to original sources

Pacemaker dependence in patients with bifascicular block during acute anterior myocardial infarction.

Eleven patients with bifascicular block complicating anteroseptal acute myocardial infarction were studied to determine the effect of prophylactic permanent pacing; eight of them also had transient high grade atrioventricular block during the acute phase of the infarction. One month after the infarction an electrophysiological study was performed and a bradycardia indicating pacemaker implanted. All the patients were followed for two years. Six had bradycardia detected, two of whom did not have high grade atrioventricular block during the index infarction. Seven patients died, four of them suddenly. There was no correlation between the electrophysiological findings and subsequent development of bradycardia. Thus pacemaker dependence seems to be common in patients with bifascicular block complicating acute myocardial infarction. Mortality is, however, also high in patients treated with pacemakers. Prospective studies to determine the predictive factors in those patients with an anterior acute myocardial infarction and who benefit from a combination of permanent pacemaker treatment and antiarrhythmic treatment are needed.

Aged

Identification of multiple pathways in the Wolff-Parkinson-White syndrome. Diagnostic problems and therapeutic implications.

With advanced electrophysiological methods evaluation of functional properties and location of accessory pathways has become possible. Multiple pathways may, however, be difficult to outline with regard to localization and electrophysiological properties due to differences in refractoriness and/or fusion of conduction between the pathways. The investigational procedures in patients with multiple accessory pathways are described and discussed in connection with an illustrative patient with three accessory pathways, two of which are Kent's bundles and one most probably a Mahaim's bundle.

Adolescent

Electrophysiological effects of lidocaine in acute myocardial infarction with bifascicular block or complete A-V block.

Electrophysiological effects of lidocaine were studied in 27 patients with acute myocardial infarction complicated by bifascicular block (group I: 20), and complete A-V block (group II: 7). Lidocaine was administered intravenously in bolus doses of 100 mg each at intervals of 10 min. In group I, there was no significant change in the heart rate (Before (B) = 84.85 +/- 24.19, After (A) = 87.25 +/- 20.26 beats/min) intra-atrial (PA) conduction time (B = 25 +/- 6.18, A = 27.22 +/- 6.69 ms), A-V nodal (AH) conduction (B = 111.5 +/- 56.12, A = 111.5 +/- 56.5 ms) or His bundle to ventricular (HV) activation time (B = 59.5 +/- 19.32, A = 61.25 +/- 18.62 ms) after lidocaine administration. In group II, 2 patients reverted to sinus rhythm, one with 1:1 conduction and the other with type II Wenckebach's block, with being prepared for the study, but both had complete A-V block within 1 h of the His bundle electrogram recordings. Of the remaining 5 patients, 4 had supra and 1 infra His A-V block. After lidocaine, 2 patients developed asystole. In the remaining 4 patients, there was no change in the escape rate or various conduction intervals.

Aged

A case of arrhythmogenic right ventricular dysplasia with ventricular fibrillation.

A case of repeated attacks of ventricular fibrillation is described. The patient suffered from an arrhythmogenic right ventricular dysplasia (ARVD) documented by right and left ventriculograms and myocardial biopsies obtained during surgical treatment of the arrhythmia. The histological changes were interpreted as being signs of fresh myocardial damage of unknown origin in addition to a replacement of the normal myocardium by adipose and fibrotic tissue. The repeated attacks of ventricular fibrillation in this patient contrast to the arrhythmia spectrum noted in the available literature on ARVD, mostly stable chronic ventricular tachycardias.

Adult

Effects of acute and chronic beta-receptor blockade on ventricular repolarisation in man.

The right ventricular repolarisation phase was studied electrophysiologically after an injection of 15 mg metoprolol in 16 healthy volunteers. Eight of them were restudied after chronic treatment with 400 mg metoprolol daily for five weeks. The assessment of the repolarisation time included ventricular effective refractory periods, monophasic action potential duration, and the QT interval measured during atrial stimulation at different driving frequencies. The acute administration of 15 mg metoprolol intravenously had no detectable effect on the repolarisation phase, while chronic treatment caused a significant increase of the ventricular effective refractory periods, monophasic action potential duration, and the QT interval during atrial stimulation. Thus the study confirmed the contrasting effect of acute and chronic beta-receptor blockade on the ventricular repolarisation time in man.

Action Potentials

Effect of intravenous melperone on atrial repolarization in man.

The effect of 10 mg of melperone intravenously on the duration of the right atrial monophasic action potential was studied in seven patients and one healthy volunteer. Melperone induced an increase of the atrial monophasic action potential duration by 13%, 15 min after intravenous injection of the drug. This prolongation was a consistent finding but was within the limits of normal intra-individual variation and considerably smaller than normal inter-individual differences. However, the observations warrant studies to evaluate the effect of the drug in different cardiac arrhythmias.

Action Potentials

Effects of metoprolol on heart rate in patients with digitalis treated chronic atrial fibrillation.

Adequate control of ventricular rate in patients with chronic atrial fibrillation (AF) may not be achieved with digitalis alone. In the present study the additional effect of two different doses (50 mg and 50 +/- 50 mg) of oral metoprolol, a new selective beta-blocking agent, on ventricular rate in patients with longstanding AF has been studied. A decrease in the mean ventricular rate during rest and during exercise at various work loads was observed after both doses. The effect was more pronounced at the highest work load of 80 W, both after 50 mg (p less than 0.002) and after 50 +/- 50 mg (p less than 0.01) of the drug. A high initial heart rate at rest or during exercise was reduced more by the drug than a lower one. Exercise tolerance was reduced in 2 patients. These results suggest that patients with AF in whom satisfactory control of heart rate cannot be achieved with digitalis alone may benefit from addition of individualized metoprolol therapy.

Adult