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Biomedical subjects

S B Olsson

Publications and source records attributed to S B Olsson.

At least 109 records · Page 6Linked to original sources
PubMed1984

Long-term oral treatment with high doses of verapamil in lone atrial fibrillation.

It has earlier been shown that verapamil given intravenously or orally in sufficiently high single doses, may result in regular ventricular rhythm in patients with atrial fibrillation. We have analyzed whether this effect of verapamil can be utilized in long-term oral treatment. Eleven patients with lone atrial fibrillation were studied. Verapamil was given in gradually increasing doses from 40 mg three times a day to 320 mg three times a day, either alone or in combination with digoxin. Resting ECG was recorded and supine and standing blood pressures were measured on each dose level. When the patients were treated with verapamil alone, only a slight decrease in heart rate was noted, while during combined treatment with verapamil and digoxin a more marked heart rate decrease occurred with increasing doses of verapamil. The variation coefficient of the RR interval, a sign of ventricular regularity, decreased during verapamil treatment regardless of whether or not digoxin was also taken. A dose-dependent blood pressure decrease was noted during verapamil treatment. Side effects were common and led to discontinuation of the attempted protocol in all patients. Three patients were unexpectedly converted to stable sinus rhythm. Five patients improved subjectively, with a marked decrease in the sensation of palpitations during intake of increasing doses of verapamil. The study indicates that chronic oral treatment with verapamil may sometimes relieve the subjective sensation of palpitations in patients with atrial fibrillation. Side effects do, however limit the value of this mode of treatment in the majority of patients.

Administration, Oral↗
PubMed1984

Acute effects of lignocaine, procainamide, metoprolol, digoxin and atropine on human myocardial refractoriness.

The acute intravenous effects of therapeutic doses of procainamide, lignocaine, metoprolol, digoxin and atropine on the monophasic action potentials (MAP) and effective refractory periods of the right ventricle (VERP) were studied in 48 healthy volunteers. Procainamide prolonged the VERP in the apex region. Lignocaine shortened the MAP duration at 90% repolarisation. Metoprolol did not affect any of the measured variables in spite of a significant decrease in heart rate. Digoxin produced a significant increase in the VERP at the outflow tract, but not in the apex region and the MAP variables did not change. Following atropine, the VERP at both recording sites decreased but the MAP signal was unaffected. In summary, the effects of procainamide, lignocaine, metoprolol and digoxin were in good agreement with previous studies in normal ventricular muscle cells in vitro. In addition, the findings following atropine, digoxin and procainamide are indicative of a parasympathetic innervation of the endocardial surface of the right ventricle.

Action Potentials↗
PubMed1984

Pathophysiology of re-entrant dysrhythmias.

Re-entry was demonstrated as a self-perpetuating mechanism as early as 1906. It may lead to single-cycle electrocardiographic phenomena as well as reciprocating tachycardias. Factors favouring re-entry are as follows. Unidirectional or temporary local block of conduction, a mechanism always involved in initiation of reciprocating rhythms but also of importance for the maintenance of the arrhythmia. Increased myocardial mass. Decreased conduction velocity. Accelerated repolarization, e.g. short refractoriness. Increased dispersion of refractoriness. Regular reciprocating tachycardias utilize re-entrant mechanisms and are found in all components of the excitable cardiac tissue. Examples of such arrhythmias are reciprocating sinus tachycardia (RST), reciprocating atrial tachycardia (RAT), reciprocating junctional tachycardia (RJT), reciprocating atrioventricular tachycardia in connection with accessory pathways and ventricular tachycardia in the chronic stages of myocardial infarction. Re-entry mechanisms are also involved in fibrillation and flutter, in atria as well as in ventricles.

Arrhythmias, Cardiac↗
PubMed1984

Amiodarone in atrial fibrillation.

Twenty-seven patients with atrial fibrillation without any concomitant conduction abnormality have been treated with oral amiodarone in a daily maintenance dose of 200 mg. The drug has been used for three purposes: 1) to block atrioventricular conduction, thereby decreasing the ventricular rate during atrial fibrillation (9 patients), 2) as prophylaxis against paroxysmal atrial fibrillation (8 patients), 3) as prophylaxis against recurrence of atrial fibrillation after DC conversion to sinus rhythm (13 patients). All patients were considered refractory to other antiarrhythmic drugs in these respects. In the second group, 4 of the 8 patients reported complete cessation of attacks and the others a marked reduction of the attack rate. In the third group, 10 of the 13 patients have maintained sinus rhythm for a longer period on treatment with amiodarone than with other drugs, resulting more than a triple prolongation of the time in sinus rhythm. In 3 patients the drug has been discontinued because of side-effects. In conclusion, amiodarone affords protection from episodes of paroxysmal atrial fibrillation, as well as from recurrence of atrial fibrillation after DC conversion to sinus rhythm. If the drug is ineffective in either of these respects, it may still be useful as a means of moderating the ventricular response in atrial fibrillation.

Adult↗
PubMed1984

Right ventricular monophasic action potentials in healthy young men.

The right ventricular repolarization phase was studied in 48 healthy men between 20 and 40 years of age. The assessment of the repolarization time included the measurement of ventricular effective refractory periods and monophasic action potentials during constant ventricular stimulation. Computer-based analysis of the monophasic action potential allowed the duration at 90% and 50% repolarization, the amplitude, the maximal upstroke velocity and the total rise time of the depolarization to be determined. These results may serve as reference values in further studies on ventricular repolarization using the same monophasic action potential recording technique.

Action Potentials↗
PubMed1984

Spatial vectorcardiography in the Wolff-Parkinson-White syndrome: correlation with epicardial mapping findings.

The spatial vectorcardiograms (VCG) of 13 patients with WPW syndrome due to single accessory pathways were analyzed and correlated with the excitation analysis obtained on epicardial mapping. The azimuth angle of the initial 10 ms cardiac vector was greater than + 90 degrees (directed right and anteriorly) in patients with a left ventricular free wall; it ranged between 0 degree to 90 degrees (left and anteriorly) in those with a left or right paraseptal free wall and was -30 degrees (left and posteriorly) in one patient with a right ventricular free wall location. The elevation angle of the initial 10 and 20 ms cardiac vector was either zero or positive (inferiorly directed) in those with right and left ventricular free wall pathway. Among six patients with a paraseptal location, the elevation angle was negative (superiorly directed) in four and positive in two. Both the patients with a clockwise inscription of a QRS loop in the horizontal plane (HP) had pathways located to the left ventricle. Among the paraseptal group, at surgery, the accessory pathway could not be excised in two in spite of dissection very close to the IV (interventricular) septum. The elevation angle in both these patients was markedly negative (-45 degrees and -62 degrees) in contrast to the other in whom surgical excision was successful.+

Adolescent↗
PubMed1984

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↗
PubMed1983

Long QT interval and ventricular tachycardia of "torsade de pointe" type in hypothyroidism.

We have observed two patients with long QT interval, ventricular tachycardias of "torsade de pointe" type and repeated ventricular fibrillation episodes, who also turned out to have significant hypothyroidism. This was suspected from the clinical picture in one patient and after haematological test in the other. In addition to hypothyroidism, both patients had associated factors which may have contributed to the development of the arrhythmia. After having reached an euthyroid state, both patients normalized their QT intervals, were relieved from earlier symptoms of cardiac arrhythmias and exhibited no longer any documented arrhythmia. Before thyroid substitution, both patients had marked signs of delayed ventricular repolarization even by invasive electrophysiological methods. Our observations indicate that hypothyroidism should be considered a possible primary cause in cases with long QT syndrome (LQTS). Furthermore, the possibility of LQTS in patients with hypothyroidism should be considered.

Adrenergic beta-Antagonists↗
PubMed1983

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↗
PubMed1982

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↗
PubMed1981

Nature of cardiac arrhythmias and electrolyte disturbances. Role of potassium in atrial fibrillation.

Atrial fibrillation is highly favoured by an accelerated atrial muscle repolarization. In hyperthyroidism, this occurs without changes in resting membrane potential level of the atrial muscle cells and without changes in the ionic composition of the cell. In patients prone to atrial fibrillation but without signs of hyperthyroidism, accelerated atrial repolarization can also be demonstrated. In such patients, a decreased atrial muscle potassium content seems responsible for the electrophysiological changes that highly favours the occurrence of atrial fibrillation.

Action Potentials↗
PubMed1981

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↗