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Biomedical subjects

S B Olsson

Publications and source records attributed to S B Olsson.

At least 19 recordsLinked to original sources
PubMed1992

Effects of diltiazem, propranolol, and their combination in the control of atrial fibrillation.

The effect of the combined treatment with propranolol 20 mg tid and diltiazem 60 mg tid in patients with chronic atrial fibrillation treated with digoxin was evaluated. Thirteen patients entered a double-blind, three-phase crossover study. Heart rate was significantly reduced during rest and at maximal exercise (p less than 0.05) during combined treatment compared with treatment with any single drug. No significant changes in maximal work load, exercise time, systolic blood pressure at maximal work load, or subjective sensation of well-being could be demonstrated during combined drug treatment. The RR distribution pattern was unaffected by the addition of propranolol, diltiazem, or their combination to the chronic digoxin treatment. It is concluded that the combination of diltiazem and propranolol has no advantages over any of these drugs singly, in the moderation of heart rate in patients with atrial fibrillation even combined with basic digitalis treatment, and that the intrinsic AV nodal function is unaffected by these drugs or their combination.

Atrial Fibrillation↗
PubMed1992

Reconstruction of the electrocardiogram during heart surgery.

Electrocardiograms (ECG) recorded during arrhythmia surgery are used for identification of arrhythmias of different morphology. However, the interpretation of an intraoperative ECG is difficult because some leads cannot be recorded and the signals of the remaining leads often differ from those of a preoperative recording because of the sternotomy. Therefore, a method for reconstruction of a complete intraoperative ECG, which resembles a preoperatively recorded ECG, was studied in 24 patients undergoing heart surgery. The reconstruction method involves calculating coefficients for a transformation matrix, using a preoperative ECG recording and a first intraoperative ECG recording. Once this matrix has been established, further intraoperative recordings can be transformed into an ECG which strongly resembles a preoperative ECG. The correlation between reconstructed intraoperative leads and the corresponding preoperative leads was high in the leads Vx and Vy (median correlation coefficient 0.98 and 0.97) and slightly smaller in lead Vz (0.94). Further studies will prove if the method can be useful in arrhythmia surgery.

Aged↗
PubMed1991

Localization of cardiac arrhythmias: conventional noninvasive methods.

Noninvasive localization of the accessory pathway (AP) in patients with the Wolff-Parkinson-White syndrome and of the site of origin of ventricular tachycardia (VT) is reviewed. 12-lead electrocardiography (ECG) is the most readily available method for localization of both the AP and the site of VT origin. Many published ECG criteria are introduced. The application of body surface potential mapping, vectorcardiography, nuclear phase imaging, echocardiography, computed tomography, nuclear magnetic resonance, and signal-averaged ECG in the localization of these arrhythmogenic substrates is also described. We believe that ECG is the most sensitive noninvasive method for AP localization as well as being convenient and simple; it may be used as the only noninvasive method for the initial evaluation. The left lateral AP, which occurs with an incidence of more than 40%, could be localized preoperatively by noninvasive methods only. For localization of the site of VT origin, none of the noninvasive methods is accurate enough for guiding the surgical and catheter-mediated ablative therapies so far.

Action Potentials↗
PubMed1991

Effect of pentisomide (CM 7857) on myocardial excitation, conduction, repolarization, and refractoriness. An electrophysiological study in humans.

The electrophysiological effects of pentisomide upon the intact human heart were evaluated using programmed stimulation and recording of intracardiac monophasic action potentials (MAP) in 17 patients with various ventricular arrhythmias. After i.v. administration of pentisomide, 85-135 mg, the atrial-His interval increased by 8 +/- 12 ms (p less than 0.05) during sinus rhythm and by 13 +/- 21 ms (p less than 0.05) at atrial pacing of 600 ms cycle length (600 ms pacing). The His-ventricular interval also increased by 6 +/- 10 ms during sinus rhythm (p less than 0.05) and by 5 +/- 9 ms at 600 ms pacing (NS). The QRS duration prolonged by 9 +/- 10 ms (p less than 0.01) and 6 +/- 8 ms (p less than 0.01) during 600 and 500 ms ventricular pacing, respectively. The right ventricular MAP duration to 90% repolarization was significantly shortened, by 20 +/- 21 ms (p less than 0.01) during sinus rhythm, by 16 +/- 17 ms (p less than 0.01) at 600 ms ventricular pacing, and by 11 +/- 16 ms (p less than 0.01) at 500 ms ventricular pacing. The corrected QT interval was shortened by 21 +/- 28 ms (p less than 0.01). The present study supports that pentisomide is a class-I antiarrhythmic agent with a marked effect on depolarization (action of class Ia and Ic) and on repolarization (action of class Ib). This unique combination of cellular electrophysiological properties indicates that the clinical antiarrhythmic efficacy of pentisomide may differ from that of hitherto available antiarrhythmic drugs.

Action Potentials↗
PubMed1990

Prophylactic treatment after electroconversion of atrial fibrillation.

Atrial fibrillation is a common arrhythmia. Sinus rhythm can often be restored by electroconversion, but the relapse rate is high. Various antiarrhythmic drugs have been used to maintain sinus rhythm after electroconversion. This article reviews the experience with these drugs and suggests a treatment strategy.

Anti-Arrhythmia Agents↗
PubMed1990

Arrhythmogenic right ventricular dysplasia in brother and sister: is it related to myocarditis?

Two cases of arrhythmogenic right ventricular dysplasia (ARVD) in siblings are reported. In the boy, 14 years old, the clinical history, ECG, echocardiography, and histopathological findings were consistent with ARVD. Premature ventricular contractions of left bundle branch block (LBBB) pattern were recorded but no ventricular tachycardia (VT). A high titer against mycoplasma and increased concentrations of immunoglobulins were found. Two years after his first admission he died suddenly. Autopsy revealed severe right ventricular (RV) myocardial damage, with fat cell infiltration and collagenous tissue. His sister presented with sustained VT of LBBB pattern 2 years later, at 12 years of age. Vaccination against rubella and signs of upper respiratory illness had preceded the symptoms. During the following 9 days ECGs and serum enzymes indicated the development of left ventricular (LV) infarction. Echocardiography revealed an enlarged RV and a normal LV. After 6 weeks both RV and LV showed akinetic areas and sacculations. We suggest that myocarditis may be a precipitating factor in ARVD, and perhaps the prerequisite for its manifestation.

Adolescent↗
PubMed1990

Thyrotoxic atrial fibrillation: an underdiagnosed or overdiagnosed condition?

Hyperthyroidism has been considered to be underdiagnosed as a pathogenetic factor for atrial fibrillation, according to results of thyroliberin stimulation tests. We assessed, clinically and biochemically, thyroid function in 110 ambulatory patients with atrial fibrillation [mean age 64 (SD 11) years] from a group of consecutive cases referred to a specialist cardiology unit during one year. Patients finally categorized as euthyroid (n = 100) commonly presented with one or more symptoms or signs considered to be typical for thyrotoxic patients. Three patients (2.7%; 95% confidence interval, 0-7.5%) fulfilled criteria for hyperthyroidism, but only one was identified from clinical examination. The thyroliberin stimulation test (performed in all patients) identified another seven patients who might have been classified as hyperthyroid according to commonly used criteria for an abnormal thyrotropin response. However, none of these seven patients was judged as hyperthyroid after follow-up. Their thyrotropin concentrations were all above the detection limit for the immunoenzymometric assay. With few exceptions, they had thyroid hormone concentrations within reference limits calculated from the results for the 100 euthyroid subjects, and their concentration ratio for free 3,5,3'-triiodothyronine to free thyroxin, 0.31 (SD 0.05), was lower than that found in the euthyroid group [0.38 (SD 0.08), P less than 0.05]. We conclude that (a) criteria for evaluating results of the thyroliberin stimulation test should be revised, (b) this test is still useful in evaluating suspected cases of hyperthyroidism, for which results of current, improved methods for thyrotropin determination are equivocal, and (c) improved diagnostic methods should be used to characterize the relative importance of hyperthyroidism as a causal factor for atrial fibrillation.

Aged↗
PubMed1989

Prediction of terminal atrial myocardial repolarisation from incomplete phase 3 data.

The duration of the monophasic action potential (MAP) carries prognostic antiarrhythmic information when the recording is done during sinus rhythm (SR) after DC conversion of atrial fibrillation (AF). This study analyses whether it is possible to predict MAP duration during sinus rhythm by analysing the atrial MAP during AF, even though complete myocardial repolarisation is never reached during this arrhythmia. We have therefore evaluated the estimated duration of the action potential (AP) and MAP by exponential extrapolation of phase 3 data. (1) AP studies were done on 11 human atrial myocardial specimens. Resting membrane potential (RMP) and AP duration were better identified when more data obtained during repolarisation were used for prediction. Thus the predicted RMP deviated on average by -0.4% of AF amplitude from the real RMP level when data to 90% repolarisation were used for extrapolation. AP duration at 90% repolarisation correlated well with the real AP duration (r = 0.88) at this level of data aquisition. (2) Continuous recording of atrial MAPs was done in 15 patients during AF and in 12 of these during SR after DC conversion. Resting myocardial repolarisation level during AF, RP(EST), and estimated MAP duration, MAPD(EST), could be calculated by exponential extrapolation in 12 patients. The actual repolarisation during fibrillation reached below 90% of the RP(EST) level in eight patients and below 70% in all 12. The MAP duration during SR could be predicted with increasing precision when data closer to the RP(EST) were used for calculation of MAPD(EST). Thus MAPD(EST) correlated well with SR MAP duration when data reaching at least 90% of RP were used (r = 0.85).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1989

Follow-up by repeated signal-averaged surface QRS in patients with the syndrome of arrhythmogenic right ventricular dysplasia.

Repeated signal-averaged surface electrocardiograms were recorded with a mean interval of 32.5 months (range 14 to 55 months) in 12 patients with the syndrome of arrhythmogenic right ventricular dysplasia (ARVD). The mean differences in the amplitude and duration of the filtered QRS complex (FQRS), the root mean square voltage of the last 40 ms of the FQRS and the duration of the terminal potentials of less than 25 microV were not statistically significant between the recordings. A wide spectrum of changes in the voltage and duration of the terminal potentials was observed, irrespective of the clinical susceptibility to ventricular tachycardia. Three patients developed changes suggesting a progression, with a decreased voltage and prolonged duration of the terminal potentials, and four patients showed the opposite pattern. In five patients the signals were stationary. It is concluded that the properties of late potentials may change with time in patients with ARVD. Follow-up by repeated signal-averaged QRS does not appear to be useful in predicting the susceptibility to ventricular tachycardia in ARVD. Its application in predicting and following progressive right ventricular morphological changes remains to be determined.

Adolescent↗
PubMed1989

Electrocardiographic findings and frequency of arrhythmias in Bartter's syndrome.

Twenty four hour electrocardiograms in 20 patients with Bartter's syndrome, a disorder associated with chronic potassium deficiency, were analysed for atrial and ventricular extrasystoles, pauses (RR interval greater than 2 s), and heart rate. The 12 lead resting electrocardiogram was also evaluated. There were slight electrocardiographic changes with ST segment depression (greater than or equal to - 0.5 mm) in seven patients, flat or low amplitude T waves in seven, and U waves (greater than or equal to + 1.0 mm) in three patients. The QT interval was prolonged in 18 patients. Nine patients had one or more ventricular extrasystoles in 24 hours. Only two patients had more than 200 ventricular extrasystoles in 24 hours. No patient had ventricular tachycardia. A total of nine patients had one or more atrial extrasystoles in 24 hours, but only one patient had more than 200 in 24 hours. One patient had an attack of non-sustained supraventricular tachycardia. No patient had pauses. Dangerous tachycardia was rare in these patients with chronic potassium deficiency caused by Bartter's syndrome. The general pattern of slight electrocardiographic changes may reflect an adaptation of the myocardium to hypokalaemia. Further studies are, however, needed to determine whether these findings are relevant to long term prognosis.

Adult↗
PubMed1989

Pre- and intraoperative identification of multiple accessory pathways. Experience of 19 pathways in 9 patients.

The pre- and intraoperative electrophysiological studies in 9 patients with two or more accessory pathways are described. The presence of multiple accessory pathways was clinically suspected in only 2 patients. During the preoperative electrophysiological study two accessory pathways were identified in 7 patients and a single pathway in 2 patients. At operation, additionally three accessory pathways were identified in 3 patients. One out of two pathways, found preoperatively, could not be confirmed in 1 patient. It is concluded that the clinical or preoperative electrophysiological evidence of only one accessory pathway should not distract one's attention from considering multiple accessory pathways in patients presenting only one type of tachycardia.

Electrophysiology↗
PubMed1988

Ventricular dimensions and wall motion assessed by echocardiography in patients with arrhythmogenic right ventricular dysplasia.

Twenty patients with arrhythmogenic right ventricular dysplasia (ARVD) and 20 healthy volunteers underwent cross-sectional echocardiographic examination for the assessment of ventricular dimensions and wall motion. Right ventricular cavity diameters and wall segments were selected from the inflow and outflow tracts and the right ventricular body. The measurement error for measuring cavity dimensions was low throughout and the reproducibility of wall motion scoring was high in both the normal subjects and the patients. All except one patient had increased dimensions and/or abnormal wall motion in the right ventricle. The right ventricular inflow tract was dilated in nine patients, the outflow tract in 11 patients and the short- or long-axis diameters of the right ventricular body were increased in seven patients. Right ventricular wall motion abnormalities, being the most frequent finding, ranged from mild hypokinesia only to dyskinesia or sacculations, and were fairly evenly distributed among the segments studied. Left ventricular abnormalities, found in eight patients, were generally mild. Cross-sectional echocardiography thus provides highly reproducible measurements of right ventricular size and contraction patterns even in patients with wall shape deformities, and is therefore a feasible non-invasive method for the evaluation of right-sided myocardial abnormalities in patients with ARVD. The diagnostic accuracy of this technique warrants further clarification.

Adolescent↗