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Twenty‐one members of a Swedish family suffering from myopathy and cardiomyopathy underwent neurological and cardiological investigations. Medical charts of 2 affected deceased patients were reviewed. Twelve patients had myopathy. The distribution of weakness was axial in mildly affected, axial and predominantly distal in moderately affected, and generalized in severely affected patients. The electromyogram showed signs of myopathy in 10 patients. Muscle biopsy specimens showed myopathic changes, rimmed vacuoles, and accumulation of desmin, dystrophin, and other proteins. Electron microscopy revealed granulofilamentous changes and disorganization of myofibrils. Several patients had episodes of chest pain or palpitations. Three men had arrhythmogenic right ventricular cardiomyopathy. Nonsustained ventricular tachycardia, atrial flutter, and dilatation of the ventricles mainly affecting the right ventricle were documented. Two of them had a pacemaker implanted because of atrioventricular block and sick sinus syndrome. Inheritance is autosomal dominant with variable onset and severity of skeletal muscle and cardiac involvement. Linkage analysis of candidate chromosomal regions showed a maximum 2‐point LOD score of 2.76 for marker locus D10S1752 on chromosome 10q. A multipoint peak LOD score of 3.06 between markers D10S605 and D10S215 suggests linkage to chromosome 10q22.3, and this region may harbor a genetic defect for myofibrillar myopathy with arrhythmogenic right ventricular cardiomyopathy.

Objective To investigate whether there is a difference in occurrence of electrocardiogram changes suggestive of myocardial ischaemia between two different doses of oxytocin.Design Double-blind randomised controlled trial Setting University hospital in Sweden.Population A total of 103 healthy women undergoing elective caesarean section under spinal anaesthesia.Methods The participants were randomised to 5 or 10 units of oxytocin, given as an intravenous bolus. A Holter monitor was used to record electrocardiograms and non invasive blood pressure and heart rate (HR) was monitored. A blood sample was obtained 12-hour postoperatively.Main outcome measures Depression of the ST segment. Secondary outcomes: symptoms, Troponon I levels, mean arterial pressure (MAP), HR and blood loss.Results There was a significant difference in occurrence of ST depressions associated with oxytocin administration, 4 (7.7%) with 5 and 11 (21.6%) with 10 units, P < 0.05. The absolute risk reduction was 13.9% (95% confidence interval, 0.5-27.3). Decrease of mean MAP from baseline to 2 minutes differed, being 9 mmHg in the 5 unit group and 17 mmHg in the 10 unit group (P < 0.01). The increase in mean HR did not differ. Troponin I levels were increased in four subjects (3.9%). There were no differences in occurrence of symptoms, Troponin I levels, or estimated blood loss.Conclusion ST depressions were associated with oxytocin administration significantly more often in subjects receiving 10 units compared with 5 units. Interventions to prevent hypotension during caesarean section may reduce the occurrence of ST depressions on electrocardiograms.

Echocardiography was used to assess normal values in the right and left ventricular cavity and wall in 127 male elite endurance athletes. M-mode and two dimensional measurements of left ventricle and left and right atria were also obtained. All subjects were high-performance orienteers, cross-country skiers and middle-distance runners. They all had a normal electrocardiogram at rest and no echocardiographic evidence of heart disease. With the use of multiple right ventricular cross-sections and two-dimensional measurements, we found a significantly greater right ventricular inflow tract and right and left atrial measurements in endurance athletes compared with earlier studies of normal, active subjects. The right ventricular free wall was slightly thicker than reported in normal active subjects but the differences were small. Left ventricular diastolic diameter was consistent with previous reports of endurance athletes. Of the 127 subjects, 13% had left ventricular wall thickness above 13 mm but none of the athletes had wall thickness above 15 mm. These data suggest that cardiac enlargement occurs symmetrically in both right and left cavities, probably reflecting increased haemodynamic loading, a mechanism by which athletes sustain a high cardiac output during exercise.

ST depression at caesarean section and the relation to oxytocin dose. A randomised controlled trial Sir, We read with interest the study by Jonsson et al. 1 and wish to comment on the authors' conclusions.The authors correctly state in the introduction that the cardiovascular side effects of oxytocin are dose-related. However, the use of 5 iu oxytocin is recommended for patients undergoing caesarean delivery by a number of regulatory societies (National Collaborating Centre for Women's and Children's Health; National Institute for Health and Clinical Excellence; and the Royal College of Obstetricians and Gynaecologists). 2 Further explanation is needed to justify the use of 10 iu oxytocin in this study, as Butwick et al. and Carvalho et al. 3,4 have shown that oxytocin doses of less than 5 iu are effective in achieving adequate uterine tone during elective caesarean delivery.The interim analysis indicated a high prevalence of ST depression (24%) in patients receiving 10 iu oxytocin. Why was the study not stopped at this time because of the observed adverse effects associated with this higher dose? In addition, the authors provide limited statistical data to validate their recruitment of an additional 50 patients following interim analysis. Their results indicate that the differences in proportion of patients with ST depression associated with oxytocin bolus between groups only barely met the criteria for statistical significance (P = 0.046).Tachycardic responses resulting from the anticholinergic effects of atropine may have contributed to ST changes. Atropine use was relatively high in each group; however, no information of the timing of atropine administration is provided. Furthermore, the use of additional oxytocin doses and other uterotonics (in the 5-iu oxytocin group) also limits direct comparisons of ST changes between 5 and 10 iu oxytocin.Peak effects on ST changes may have occurred earlier than reported in the study, as Dyer et al. and Svanstrom et al. 5,6 have shown that peak peripheral vascular effects and electrocardiogram (ECG) changes are observed within 60 seconds of the administration of oxytocin.Despite these apparent limitations, this study adds to current evidence supporting the use of a bolus of £5 iu oxytocin during elective caesarean delivery, so as to minimise cardiovascular oxytocin-related side effects. Future work should focus on investigating optimal oxytocin infusions for the maintenance of adequate uterine tone following oxytocin bolus administration. We question whether there is relevant scientific justification for further investigations of the administration of >5 iu oxytocin for patients undergoing elective caesarean delivery. j References