[Cell morphology in immunosuppressive treatment of lymphocytic myocarditis].
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Adult↗
Biomedical subjects
N Edvardsson
Publications and source records attributed to N Edvardsson.
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↗
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↗
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↗
Clinical course, serum concentrations and elimination rate in a case of massive sotalol intoxication.
A young woman had been on antiarrhythmic treatment with sotalol 80-160 mg daily for three years because of ventricular tachycardia. After a quarrel she ingested an overdose of sotalol, estimated to be 13-14 g, and was immediately brought to hospital, where the first ECG was taken 25 minutes after the ingestion. The clinical course, including the relationship over time between pronounced bradycardia, QT prolongation and malignant ventricular tachyarrhythmias is described. Serum concentrations were obtained regularly between 11 and 54 hours after the ingestion. After initially very high levels, the concentrations decreased in a strictly exponential manner to arrive at therapeutic concentrations 39 hours after the ingestion. Calculations revealed that over 12 g of sotalol was absorbed into the circulation, while the half life was 9.2 h and the oral clearance 294 mg min-1. The heart rate normalized about 24 hours after the repolarization variables, which supports the opinion that the class III action of sotalol is unrelated to the beta-blockade. In sotalol intoxication, malignant tachyarrhythmias appearing during excessive prolongation of the QT interval, most often in combination with hypokalemia, ethanol intoxication or concomitant antiarrhythmic treatment, may need emergency defibrillation but seem to disappear within a few hours. Thus, while massive sotalol intoxication may be fatal, early treatment promotes a successful outcome even when very high doses have been ingested.
Adult↗
Transesophageal versus intracardiac atrial stimulation in assessing electrophysiologic parameters of the sinus and AV nodes and of the atrial myocardium.
Electrophysiological parameters of the sinus and AV nodes and of the atrial myocardium were assessed with both transesophageal atrial stimulation (TAS) and intracardiac atrial stimulation (ICS) in the same patient during the same study. The study group was comprised of nine men and seven women, aged 45 to 79 years, referred for the evaluation of syncope of possible arrhythmogenic origin. Twelve patients were included for analysis. Autonomic inhibition (AI) was obtained in five patients. The most striking result was the significantly longer AERP with TAS (mean 286 +/- 9 ms) than with ICS (mean 244 +/- 12 ms; p than 0.02). After AI, the AERP was even more prolonged with TAS (mean 332 +/- 20 ms) than with ICS (mean 237 +/- 8 ms; p less than 0.01). Intraatrial and AV nodal conduction times assessed at multiple paced cycle lengths were significantly shorter with TAS than with ICS. There was no difference between TAS and ICS with regard to AVERP, Wenckebach periodicity and H-V intervals. Although a tendency towards shorter sinus node recovery time (SNRT) and sinoatrial conduction time (SACT) was observed with TAS, the difference was not statistically significant. Possible mechanisms of the differences are discussed. It seemed clear that the site of origin of an atrial impulse can have definite effects upon excitability and conduction properties of atrial and AV nodal fibers. Enhanced sympathetic activity during TAS was also suggested. The electrophysiological properties inherent in the TAS technique warrant further elucidation.
Aged↗
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↗
Arrhythmias in ischemic heart disease.
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Anti-Arrhythmia Agents↗
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↗
Paroxysmal vagally mediated AV block with recurrent syncope.
Paroxysmal complete atrioventricular (AV) block without associated electrocardiographic (ECG) abnormality is not a well recognized entity. A mother and her daughter had recurrent syncopal episodes, but a normal ECG. The episodes were preceded by nausea and vomiting. ECG during these episodes revealed complete heart block. In the mother, one episode was promptly reversed by atropine. Electrophysiological evaluation of the sinus and AV nodal function and atrial and ventricular effective refractory periods before and after autonomic blockade was normal. Provocative manoeuvres failed to induce AV block. Paroxysmal AV block was vagally mediated in one of the patients, as indicated by prompt response to atropine. In the second case, the vagal dependence could not be proved but appears to be the most likely explanation. It thus appears that paroxysmal, vagally mediated complete AV block should be seriously considered in patients with unexplained syncope.
Adult↗
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↗
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↗
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↗
Göteborg Metoprolol Trial: effects on arrhythmias.
During the initial hospitalization, ventricular fibrillation (VF) developed in 6 metoprolol-treated patients (0.9%) vs 17 placebo-treated patients (2.4%) after inclusion in the study (p = 0.035). There were 6 episodes of VF in the metoprolol group compared with 41 episodes in the placebo group (p less than 0.001). During the same period, 14 metoprolol-treated patients had treated ventricular tachycardia vs 26 placebo-treated patients (p = 0.076). Similar favorable results were found when the incidence of severe ventricular arrhythmias during the first rehospitalization within the 3-month double-blind treatment period was analyzed.
Adult↗
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↗
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↗
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↗
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↗