Hemodialysis, in contrast to CAPD, improves parasympathetic function in ESRD patients.
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Biomedical subjects
Publications and source records attributed to C Chiarini.
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A longitudinal analysis of blood pressure was performed in 30 patients on hemodialysis for at least 10 years, in order to clarify the long-term outcome of hypertension in dialysis patients. Before the start of the dialysis treatment 22 (73.3%) patients were hypertensive, while, after 10 years, only 5 (16.6%) were still hypertensive. Body weight tended to decrease progressively throughout the period of observation. Hypertension disappeared in the younger patients while it remained/appeared in those who were order showing the characteristics of systolic hypertension. Except for hematocrit no significant differences in metabolic findings were found between normotensive and hypertensive patients. ECG abnormalities were found to be more frequent after 10 years of dialysis than before the start of treatment. High blood pressure tends to disappear progressively in hemodialysis patients and to be no longer a problem in long-term survivors.
1 The effect of captopril on autonomic reflex functions has been investigated in fifteen patients with essential hypertension by examining their responses to tests of baroreceptor function (Valsalva's manoeuvre and upright posture), sympathetic nervous system reactivity (cold pressor and mental stress tests) and parasympathetic reactivity (diving test) before and after 3 weeks' treatment with captopril. 2 Captopril significantly reduced arterial blood pressure and resting heart rate but did not affect cardiovascular responses to Valsalva's manoeuvre, upright posture, cold pressor and mental stress tests. 3 The bradycardia associated with the diving reflex test was significantly enhanced by captopril (P less than 0.01). 4 These results indicate that treatment with captopril is associated with increased parasympathetic tone but without inhibition of baroreceptor or sympathetic reflexes.
This paper compares renal scintigraphy (RS) with renal vein renin activity (RVRA), intravenous pyelography (IVP), and peripheral plasma renin activity (pPRA) in a population of hypertensive subjects with suspect renovascular hypertension (RVH), of whom 30 underwent surgery, in order to evaluate (a) screening ability of RS for RVH, and (b) surgical prognosis of RS for RVH. RS agreed with arteriographic findings of arterial stenosis in 91% of patients and proved more sensitive as a screening test than IVP and pPRA. The false-negative rate of RS was 9% and the false-positive rate was 10%. In the patients who underwent surgery RS was positive in 89% and RVRA in 85% of those who benefited from surgery. In this series false-negatives for RS occurred only in the presence of extensive collateral circulation, where RVRA also gave the same result. In patients who had been operated on, the sensitivity and specificity of RS, compared to RVRA, were very high. Our work supports the view that RS is a good screening test in RVH; moreover, it seems to be as accurate as RVRA as a surgical prognostic method for curable RVH.
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Captopril was administered to 12 essential hypertensive patients with low or normal plasma renin activity in order to evaluate its effectiveness in decreasing blood pressure and to determine whether the inhibition of converting enzyme could interfere with sympathetic neural activity. Captopril, at the doses of 150-450 mg/die, normalized blood pressure in 5 patients (responders) and had no effect on 7 patients (non responders). A significant decrease in heart rate was observed in all patients. Captopril failed to significantly increase plasma renin activity in all patients. Supine plasma levels of catecholamines were significantly higher in responders compared with non responders and decreased significantly after treatment with captopril. The physiological study we performed on all patients suggests an overall integrity of the baroreceptor reflex arc and vascular reactivity to stress before as well as after treatment with captopril. On the contrary, the bradycardia induced by diving test was significantly greater after treatment than before therapy. These findings suggest that the antihypertensive effect of converting enzyme inhibition may be partly due to interference with sympathetic neural activity. Moreover captopril seems to exert an important effect on parasympathetic activity irrespective of blood pressure changes.
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The authors have studied the autonomic function in a group of 34 regular hemodialyzed patients and in a group of 24 normal volunteers with simple, non-invasive and repeteable techniques. To evaluate autonomic function Valsalva manoeuvre, cold pressor test, mental stress test, tilt test, diving reflex test, systolic-time intervals and plasma catecholamines levels were used in all subjects. Uremic patients on maintenance hemodialysis were studied the day after hemodialysis. The response to cold pressor test, mental stress test, tilt test and plasma catecholamines levels resulted normal in all uremic patients, even if 17 out of 34 patients showed an abnormal response to the Valsalva manoeuvre (Valsalva ratio lesser than 1.40). In these patients an alteration of diving reflex and/or a pathological systolic-time interval was found. The authors suggest that sympathetic function is normal in regular hemodialyzed patients and that the abnormal response to the Valsalva manoeuvre is probably due to a defect in the vagal control of the heart and/or an alteration of cardiac performance.
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A study of the frequency distribution of plasma renin activity (PRA) in 123 patients with essential hypertension (EH) produced no evidence of a distinct subpopulation with low renin levels, whether the samples were taken from supine or upright patients. Applying an arbitrary classification criterion, however, low PRA levels were found in 30.1% of patients. There were no significant differences in mean blood pressure, 24-h sodium excretion, and age when groups with low, normal or high PRA levels were compared. The incidence of PRA hyporesponsiveness was similar in the three groups of patients, but increased with age. In the female there was apreponderance of low PRA levels. It is concluded that EH with low PRA levels is not a separate diagnostic entity and, when PRA is low in a hypertensive subject, the possible effects of age, blood pressure, and sex ought to be taken into account before other causes of low PRA are postulated.
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