Search PubMed⌕ Search

Biomedical subjects

S B Olsson

Publications and source records attributed to S B Olsson.

At least 91 records · Page 5Linked to original sources
PubMed1988

Cardioangiographic findings in patients with arrhythmogenic right ventricular dysplasia.

The dimension, contractility, and regional wall motion of the right and left ventricles were scored on the angiograms of 13 patients with arrhythmogenic right ventricular dysplasia. In 10 patients the right ventricle was enlarged, in eight the contractility of the right ventricle was reduced, and in all but one patient there were regional wall motion abnormalities of the right ventricle. The most common abnormality of regional wall motion was mild hypokinesia. There were bulging or dyskinetic areas in seven patients. Regional wall motion abnormalities of the left ventricle were found in five patients, two of whom also had bulging or dyskinetic areas. The reproducibility of right ventricular dimension, contractility, and regional wall motion scores was generally fair but varied unexpectedly both within and between two observers (Kendall's Tau 0.38-0.92). The score values of regional wall motion for some of the segments differed considerably within and between observers. One of the observers consistently gave higher scores than the other. These data suggest that a more objective approach is needed for evaluating angiographic changes in arrhythmogenic right ventricular dysplasia.

Adolescent↗
PubMed1987

Arrhythmogenic right ventricular dysplasia presenting with ventricular tachycardia in a father and son.

A father and his son presented with ventricular tachycardia of left bundle-branch block configuration, two years apart. The patients had no clinical signs of right or left ventricular dysfunction. The diagnosis of arrhythmogenic right ventricular dysplasia was based on right ventricular angiographic and radionuclide findings. Microscopic sections obtained at surgery for the ventricular tachycardia in the father revealed abnormal infiltration of fat and focal fibrosis in the right ventricular myocardium, confirming the diagnosis. The importance of thorough evaluation of right and left ventricular function and structure in patients with ventricular tachycardia of right ventricular origin is emphasized. Currently available diagnostic techniques and management are presented.

Adolescent↗
PubMed1987

Methodological aspects of the use of heart rate stratified RR interval histograms in the analysis of atrioventricular conduction during atrial fibrillation.

A new computer assisted method for analysing RR interval histograms was devised in 32 patients with sustained atrial fibrillation. Twenty four hour ECG recordings were divided consecutively into periods with 64 heart beats and mean heart rates calculated for each period. Using increments of 10 beats.min-1 serial heart rate stratified histograms with 5120 RR intervals were constructed according to the calculated heart rate. In all histograms the RR intervals were sorted into 20 ms wide subgroups between 180 and 2100 ms. The analysis showed a bimodal RR distribution in 26 patients. Several indices were chosen to characterise a given RR interval peak in the histogram analysis. The rate dependence of peak was calculated for each individual peak. In the presence of two or more peaks a peak dominance change value was defined. Furthermore, differences and ratios between peak values at peak dominance change value (peak gap and peak value ratio) were calculated. A contour index was used to describe the smoothness of the appearance of the histogram. Comparisons were made between the histograms with periods composed of different numbers of heart beats (8, 16, 32, 64) for the mean heart rate calculation and between the histograms constructed with different numbers of RR intervals (512, 1024, 2560, 5120, 10,240, pooled data) in six patients. A significant finding was that greater than 5000 RR intervals should be used for the construction of a heart rate stratified histogram. Comparison was also made between the repeated histograms with a mean time interval of 137 days (7-413 days) in eight patients. The findings showed a high reproducibility of the heart rate stratified histogram.

Atrial Fibrillation↗
PubMed1987

Clinical value of plasma concentrations of antiarrhythmic drugs.

The clinical use of plasma concentrations of antiarrhythmic agents suffers from important limitations. Any factor changing the protein binding capacity affects the free, clinically active, fraction of the drug. Most antiarrhythmic agents attach to the acute phase alpha-1-acid glycoprotein, varying during conditions such as acute myocardial infarction, leading to changes in the plasma binding capacity for e.g. lidocaine. Several pharmacodynamic factors may counteract or potentiate the electrophysiological or haemodynamic action of antiarrhythmic agents. Active metabolites contribute to the clinical efficacy or to the side-effects. The induction of metabolizing enzymes of some drugs and the inhibition of hepatic metabolism of others may change the free drug fraction in plasma. While many studies show a good correlation between plasma levels and antiarrhythmic effect, few imply a correlation between plasma levels and a decrease in mortality. However, in spite of these limitations, plasma levels may be useful in guiding treatment with high dosages, with drugs with long elimination half-lives, in treatment failures due to true failure of the drug, changes in pharmacokinetics or because of poor patient compliance, and may be of particular interest when side-effects and/or intoxication are suspected.

Anti-Arrhythmia Agents↗
PubMed1987

Precision of preoperative electrophysiological study in predicting the intraoperatively defined location of single left-sided accessory pathways.

In 34 patients with a left-side anomalous pathway (AP) considered for arrhythmia surgery, the atrial insertion of the anomalous pathway in the preoperative investigation was determined by using three different techniques. The atrial activation sequence during orthodromic tachycardia or ventricular stimulation was recorded in the coronary sinus by using either (a) unipolar leads from an eight-polar electrode catheter with an interelectrode distance of 1 cm, (b) bipolar leads from consecutively positioned pairs of electrodes on the same electrode catheter or (c) bipolar leads recorded at one centimeter intervals by withdrawal of the electrode catheter. The corresponding location at surgery was obtained by atrial epicardial mapping during ventricular stimulation. Each way of recording the atrial activation sequence in the coronary sinus during orthodromic tachycardia or ventricular stimulation was compared with regard to their predictive value in assessing the corresponding location by intraoperative mapping. At surgery, a visual grid system was used to define the anatomical landmarks which were located 20 mm apart. When the unipolar technique was used to assess the anomalous pathway location, there was a difference corresponding to a distance of 2-2.5 anatomical landmarks (48 mm) between the preoperative and intra-operative assessments. With the bipolar technique the difference was up to 3 anatomical landmarks (60 mm) while it was up to 4.5 anatomical landmarks (90 mm) when the withdrawal technique was employed. The unipolar technique was superior in differentiating a left lateral from a left posterior or a septal location.

Adolescent↗
PubMed1987

A long term follow up of 15 patients with arrhythmogenic right ventricular dysplasia.

The clinical course in 15 patients with features consistent with arrhythmogenic right ventricular dysplasia is described. At referral seven patients had abnormal physical findings, nine had abnormal electrocardiograms with non-specific right-sided abnormalities, and seven patients had increased heart size or prominent right ventricles on chest x ray. During long term follow up (mean 8.8 years, range 1.5 to 28 years) 11 patients had abnormal physical findings, 11 had electrocardiographic changes, and nine had increased heart size. Recurrent sustained right ventricular tachycardia was the most common arrhythmia (10 patients). Two patients experienced ventricular fibrillation. Seven patients suffered from over 10 episodes of ventricular tachycardia, nine required cardioversions, and 10 patients had associated serious symptoms such as syncope, severe hypotension, or cardiac arrest. Four patients required operation to correct the arrhythmia and three patients developed right heart failure. Two out of three deaths were sudden. These data suggest that in arrhythmogenic right ventricular dysplasia right ventricular abnormalities may be progressive and that the condition may affect the left ventricle. The course of the ventricular arrhythmias was highly variable and could not be predicted in individual patients. The potential for lethal ventricular arrhythmias is evident and warrants intensive diagnostic efforts to identify patients with adverse prognostic features.

Adolescent↗
PubMed1987

Amiodarone photoreactions.

Four patients with photoreactions after Amiodarone therapy are described. The action spectrum for photosensitivity was found in the UVA region. Pigmentation seems to be due to wavelengths below 360 nm.

Aged↗
PubMed1986

Transseptal left heart catheterization: a review of 278 studies.

In our laboratory, we performed 278 transseptal left heart catheterizations in adult patients over a period of 13 years. The left atrium was entered in 91.4% of the intended left heart catheterizations. Of 252 attempts, the left ventricle was entered in 96.1%. Major complications were aortic puncture (0.7%), pericardial puncture/suspected tamponade (3.2%), systemic arterial embolism (1.1%), and suspected perforation of the inferior vena cava (0.4%). There were no deaths. Although less frequently performed during the last decade, the transseptal catheterization technique has a complication rate of the same magnitude as during periods when this method was more commonly applied.

Adolescent↗
PubMed1986

Surgical treatment of the WPW-syndrome--experience in 30 initial cases.

Between May 1980 and February 1985, 30 patients were operated upon at Sahlgren's Hospital for life-threatening or disabling arrhythmias, caused by Kent's bundles. Two surgical methods were used. The outcome of surgery was fully satisfactory in 19 patients, whereas 4 patients continued to have arrhythmias after surgery. Six patients had a modified delta-wave in the ECG after surgery, but their arrhythmias could be controlled by antiarrhythmic medication. One patient died after surgery due to an undiagnosed cerebral tumor. There were 2 late deaths, between 6 and 12 months postoperatively; neither of these was caused by arrhythmias.

Adolescent↗
PubMed1986

Noninvasive support for and characterization of multiple intranodal pathways in patients with mitral valve disease and atrial fibrillation.

Twenty-four-hour ambulatory ECG recordings were made in 22 patients with mitral valve disease and sustained atrial fibrillation. Computer analysis was used to stratify 64-beat periods according to the average ventricular rate levels. The distribution of pooled RR-intervals from heart-rate levels 50-60, 60-70 ... 160-170 were then presented as histograms, using a 20 ms width. This heart-rate stratified analysis revealed a bi- or trimodal RR-distribution in 16 of the 22 patients. This finding was interpreted as indicating the presence of two separate atrionodal pathways and in some cases nodal escape activity in addition. A limited heart-rate range may have obscured this phenomenon in 5 of the 6 cases without signs of bimodality. At high heart rates, AV-nodal conduction occurred via a 'fast pathway' whilst at successively lower heart rates, this conduction was blocked and a 'slower pathway' was used instead. In addition, at successively slower rates, the dominant cycle of conduction via either pathway tended to lengthen according to a linear relationship. The change of dominance from the fast to the slow pathway occurred between 90 and 120 beats per minute in almost all cases. The further electrophysiological characterization of patients with 2 pathways was done by calculation of differences and ratios between lengths of dominant cycles of different pathways at the rate of change of dominance. The findings may serve as reference data for further studies of AV-nodal conduction using the same method. Furthermore, the study strongly indicates that dual AV-nodal pathways are an ubiquitous phenomenon and supports the hypothesis that even in man, AV-nodal input follows two main routes: along the crista terminals between the coronary sinus and the tricuspid valve and from the interatrial septum.

Aged↗
PubMed1986

Effect of long term treatment with metoprolol and sotalol on ventricular repolarisation measured by use of transoesophageal atrial pacing.

The effects of long term (4 weeks) treatment with oral metoprolol (100 mg twice daily) and sotalol (160 mg twice daily) on ventricular repolarisation time were compared in a double blind crossover study in 20 patients post-infarction. For QT interval studies transoesophageal atrial pacing was performed at a cycle length of 800 ms. Sotalol prolonged the QT interval by 5-7% compared with metoprolol. The prolongation reflects a change in the repolarisation time because there was no change in the QS interval. Measurements of heart rate at rest and during bicycle exercise indicated that metoprolol and sotalol in the doses selected were equipotent as beta blockers. Transoesophageal atrial pacing is a simple non-invasive method with few and mild side effects that is well suited to drug studies.

Aged↗
PubMed1985

Adaptation of human atrial muscle repolarisation after high rate stimulation.

We analysed the effect of a sudden change from a high rate of stimulation to a "physiological" rate upon the repolarisation of human atrial muscle. Microelectrode technique was used to study the effect upon the action potential (AP) recorded from myocardial specimens obtained during open heart surgery in nine patients. Suction electrodes were used to record monophasic action potentials (MAPs) in 12 patients undergoing electroconversion of atrial fibrillation. The abrupt change from 30 min of high-rate stimulation of the atrial specimen to a pacing rate of 60 per min resulted in a successive prolongation of the atrial myocardial AP duration so that 50% of the prolongation was reached after 3 min according to an exponential analysis. A similar prolongation of repolarisation was seen in the MAP recordings after conversion of atrial fibrillation to sinus rhythm and during regular atrial stimulation at a rate of 100 per min. In these recordings, the time needed to reach 50% of the prolongation of the MAP after DC conversion was about 7 min. The findings demonstrate that human atrial muscle undergoes an adaptation of repolarisation after abrupt slowing from a fast stimulation rate. A steady-state level of the AP or MAP duration is reached 10 to 15 min after the change of rate. Together with earlier studies, these experiments indicate, that when right atrial MAP recording is done for assessment of the likelihood of the patient's remaining in sinus rhythm after conversion of atrial fibrillation, the recording must be made within a few minutes of the conversion.

Action Potentials↗
PubMed1985

Induction of delayed repolarization during chronic beta-receptor blockade.

The development of delayed ventricular repolarization was studied in eight patients with clinical indication for chronic beta blockade. Their mean age was 74 years (range 69-81 years) and they all had permanent pacemakers for syncope. The ventricular repolarization time was assessed by means of the Q-T top interval during ventricular stimulation at different paced heart rates. In a group of seven other patients there was a close relationship between the right ventricular monophasic action potential duration at 90% repolarization (RV MAPD90) and the paced Q-T top interval (r = 0.90). After three weeks of treatment with 200 mg metoprolol daily, the paced Q-T top interval increased significantly (3-4%, P less than 0.001) at all paced heart rates, while after about two weeks of treatment a significant increase was seen only at the paced heart rate of 130 beats min-1 (P less than 0.01). Thus, the present study confirmed the development of delayed ventricular repolarization within three weeks of treatment with 200 mg metoprolol daily. The onset of this effect was first noticeable after about two weeks of treatment. Furthermore, the close relationship between the RV MAPD90 and the paced Q-T top interval implies that the paced Q-T top interval may be a reliable and useful feature to detect changes in the ventricular repolarization time.

Aged↗
PubMed1985

Estimation of ventricular repolarization in man by monophasic action potential recording technique.

Myocardial monophasic action potentials (MAP) can be recorded with the aid of suction or contact electrodes applied endocardially via a catheter. The technique necessitates high input impedance amplifiers with infinite time constant. A bipolar technique improves signal quality with regard to electrical contamination around the rapid upstroke of the MAP. Mechanical artefacts in the recordings are common and may be explained by catheter movement induced by atrial or ventricular contractions. The MAP signal can be used for a precise measurement of time of local excitation and for the study of atrial as well as ventricular repolarization. The technique has mostly been applied in the exploration of atrial and ventricular repolarization in healthy hearts and during different cardiac arrhythmias. Furthermore, several studies have documented the electrophysiological action of antiarrhythmic drugs upon the human heart. Concluding from 576 different investigations we consider the technique to have no serious side-effects.

Cardiac Catheterization↗
PubMed1985

Effects of lidocaine, procainamide, metoprolol, digoxin and atropine on the conduction of premature ventricular beats in man.

The acute electrophysiologic effects of clinical doses of procainamide, lidocaine, metoprolol, digoxin and atropine upon the conduction of ventricular premature beats, were studied in 48 healthy volunteers. The conduction time of the first premature beat, induced 1 ms after the ventricular effective refractory period (VERP) was longer than that of the basic paced beats in 41 of the 48 subjects (85%); in 31 (65%) the delay was greater than 5 ms, indicating subnormal conduction. Digoxin decreased the delay so that it became insignificant, while, after procainamide, the delay increased significantly. The other agents did not significantly affect the subnormal conduction. The mean conduction times of premature beats, induced 30-50 ms after the VERP, were shorter than the basic conduction time in 43 of the 48 subjects (90%), and in 25 (52%) the decrease was greater than 5 ms, showing supernormal conduction. Lidocaine abolished the supernormal conduction. The other agents did not significantly alter the supernormal conduction. In the healthy heart, sub- and supernormal conduction of premature beats seem to be common phenomena, and seem, with few exceptions, to be largely unaffected by clinical doses of procainamide, lidocaine, metoprolol, digoxin and atropine.

Action Potentials↗