The link between increased QT dispersion and cardiac death in subjects with diabetes and arterial disease is well recognised. Corrected QT dispersion was studied in subjects with end stage renal failure on haemodialysis. Thirty one stable, chronic subjects on haemodialysis had 12-lead electrocardiograms (ECGs) taken before and after a single haemodialysis session. The QT interval was measured manually in each and the corrected QT and corrected QT dispersion calculated. Serum concentrations of potassium, calcium, and magnesium were measured at the same time as ECG acquisition. Corrected QT dispersion increased from a mean (SEM) 90.6 (5.8) to 117.7 (10.2) ms (p=0.002). Serum potassium and magnesium decreased from 5.0 (0.14) to 3.5 (0.09) mmol/l and 0.95 (0.04) to 0.89 (0.09) mmol/l respectively, while serum calcium increased from 2.56 (0.04) to 2.77 (0.04) mmol/l. Intradialytic weight fell by a mean of 2.1 kg. There was no significant correlation between the change in QTc dispersion and the changes in measured serum anions or the subjects' weight during dialysis. Corrected QT dispersion was higher in subjects on haemodialysis than previously suggested normal values, and was significantly increased by haemodialysis. This reflects increased inhomogeneous ventricular repolarisation, which may lead to an increased risk of arrhythmias and sudden death. Studies looking at QT dispersion in subjects on dialysis should standardise the timing of ECG recordings taken with respect to dialysis.C ardiovascular disease is a major cause of mortality and morbidity among subjects on haemodialysis. Cardiovascular death is responsible for up to 50% of deaths among subjects on dialysis. 1 Cardiac arrhythmias are frequent among the haemodialysis population, particularly during and immediately after a dialysis session. 2-5 These arrhythmias may be caused by the rapid changes in intracellular and extracellular electrolytes during the dialysis session, in hearts that are susceptible due to both myocardial ischaemia and intramyocardiocytic fibrosis. 6 7 A reliable way of predicting subjects at risk of ventricular arrhythmias would be an extremely useful tool for the dialysis physician.Recently, dispersion of the QT interval has emerged as an important predictor of ventricular arrhythmias. The QT dispersion is simply the difference between the shortest and longest QT interval on a standard surface 12-lead electrocardiograph. 8 This is a non-invasive measurement of myocardial repolarisation inhomogeneity and hence predisposition to re-entry arrhythmias. 9 A QT dispersion above 80 ms reflects a loss of synchronisation in the repolarisation process. 10 In clinical studies, a wide QT dispersion has been shown to be a risk factor for cardiac arrhythmia after myocardial infarction, 11 congestive cardiac failure, 12 peripheral vascular disease, 13 and drug induced arrhythmiogenicity. 14 It has also been shown that a wide QT dispersion can narrow when congestive cardiac failure is treated with enalapril 15 and after successful thrombolysis for acut...
Ultraviolet radiation of wave lengths from 2800 Å to 3100 Å, generated by a General Electric RS sun lamp, was used to irradiate eggs and alevins of the sockeye salmon (Oncorhynchus nerka). Mortality curves are presented for a series of measured dosages. Irradiation of eggs in the later stages of development produced a stimulating effect on the rate of hatching. These premature alevins, which hatched a month before the controls, were abnormal in several respects. The vertebral column was curved downward over the region of the heart, growth was retarded, the yolk was not utilized as rapidly as in the controls and pigmentation was delayed. The mortality was particularly high at the time of hatching and the process was abnormal. Histological examination of irradiated alevins revealed changes in the epidermis and fibroelastic layers of the skin. These were localized to the irradiated regions. Heavy doses produced severe degeneration of the epidermal layer with the formation of granules in the nuclei, the breakdown of the goblet cells, and subsequent desquamation. The changes were less extreme with lower dosages and in these fish a recovery began about 13 days after irradiation. Internal organs and tissues beneath the fibroelastic layers of the skin were not visibly affected by the irradiation.
To investigate the pathophysiology of hypertension in patients receiving recombinant human erythropoietin (rHuEpo) we studied its effects on the renin-aldosterone axis of chronic haemodialysis (HD) patients not receiving antihypertensive drugs. Nine severely anaemic normotensive HD patients received rHuEpo 50 U/kg bodyweight, thrice weekly after each HD. The dose was increased by 25 U/kg bodyweight every 4 weeks to a maximum of 100 U/kg or until an increase of Hb or Hct of 2 g/dl or 7% was achieved. Blood samples were taken after 30 min supine rest and while seated 10 min later after gentle ambulation. Results expressed as mean +/- SEM: therapy in normotensive HD patients by a negative feedback loop, before the development of hypertension.
A16-year-old apprentice electrician was referred with nephrotic syndrome. He had a 3-month history of swelling of the ankles, eyelids and face. Asthma had been diagnosed at the age of 11 years and had been treated with inhaled salbutamol and beclomethasone. As a young child he had also required intermittent courses of oral prednisolone. In his mid teens he had been referred to his local paediatrician for investigation of short stature. Between the ages of 11 and 15 years his height and weight had fallen from the 92nd to the 12th and from the 85th to the 3rd centiles respectively. After investigation the growth retardation was attributed to his oral steroid use. On examination he appeared well. Secondary sexual characteristics were absent, blood pressure was 100/70 mmHg, there was moderate ankle and periorbital oedema. No other abnormalities were detected. Investigations were as follows: 12.3g urinary protein/24 hours, serum creatinine 95 mmol/litre, creatinine clearance 64 ml/min, serum cholesterol 7 mmol/litre, erythrocyte sedimentation rate 90 mm/hr, haemoglobin, 11.3 g/litre and mean corpuscle volume 69 fl. Tests for thyroid function, ferritin and iron studies, blood sugar, C-reactive protein, immunoglobulins and serum electrophoresis, complement levels, antinuclear antibody, extractable nuclear antigen antibodies, antineutrophil cytoplasmic antibodies and antiglomerular basement antibody were all normal or negative. The proteinuria was shown to be highly selective and he was treated empirically with prednisolone 40 mg daily, ranitidine 150 mg twice daily and frusemide 40 mg daily. His nephrotic syndrome proved refractory to treatment and he was admitted with worsening leg oedema. The diuretic dosage was increased and with informed consent a percutaneous renal biopsy was performed. This showed glomerular deposition of structureless eosinophilic material in the mesangium that extended into the glomerular basement membrane. The material stained positive for amyloid by Congo red. Electron microscopy confirmed the presence of typical amyloid fibrils in the glomeruli, vessels and around the tubules. Histopathologically it was impossible to determine whether this was primary or secondary amyloidosis. A search for causes of secondary amyloidosis was undertaken. In view of the history of asthma a salt sweat test and chest computed tomography were performed. These showed no evidence of cystic fibrosis or bronchiectasis respectively. Belatedly the patient mentioned that he had longstanding but intermittent central abdominal discomfort which he had always considered to be ‘normal’. He had, however, noticed that it had improved while he was on steroid treatment. A subsequent barium meal and follow-through showed a tight elongated stricture of the terminal ileum of approximately 10–20 cm. The patient was referred for right hemicolectomy. Preoperatively he was shown to have abnormal short and long synacten tests but the operation proceeded with hydrocortisone cover. Two macroscopically typical lesions of Crohn's disease measuring 2 and 15 cm were found affecting the terminal ileum. The other abdominal organs and pelvis were normal. A routine right hemicolectomy was performed. The patient recovered from the operation uneventfully. Histological examination of the terminal ileum showed a chronic transmural infiltrate with granulomata. The mucosa was ulcerated and fissured. Amyloid deposition was noted in the submucosal vessels (Figure 1). His immediate postoperative course was uncomplicated. Over the following months and years his ankle oedema disappeared and he achieved sexual maturity. The proteinuria fell and when last measured, 4.5 years after the procedure, was 0.8g/24 hours (Figure 2). The serum albumin also rose to the normal range. His hydrocortisone was discontinued in 1995 following which a repeat short synacthen test was normal. Creatinine clearance rose to 110 ml/min. A repeat renal biopsy was considered to be unnecessary.
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