Biomedical subjects
Publications and source records attributed to I Maragno.
Two patients with hypertension due to coarctation of the aorta were treated for 12 weeks with captopril at increasing doses. After an immediate response, resistance developed to captopril, which was associated with restoration of initially elevated renin and plasma aldosterone levels. Lack of hypertension control may be related to long-term reappearance of mechanisms which lead to excessive renin stimulation.
The effect of muzolimine (initial dose 60 mg followed by 30 mg/day for 14 days) on 15 patients with aortic and mitral incompetence and chronic cardiac failure, functional class 3, was analyzed on the basis of repeated clinical observations, metabolic studies as well as mono and bidimensional echo changes 2, 24 hours and 15 days after the initial dose. An important variation was a reduction in body weight by 3-4% after the first day and by a further 1-2% after 2 weeks. No significant variations were observed regarding heart rate and blood pressure at rest. Plasma level of electrolytes as well as other important biochemical parameters in the serum (BUN, glucose and creatinine) were uninfluenced. A small increase was observed in both the plasma level of chloride and in the red cell count. Urine volume increased by two to threefold after the first day; this increase was still present after 2 weeks. Changes in the left ventricular end-diastolic and end-systolic volumes were not significant after the first day; however a slight but significant reduction was observed after 2 weeks and was in parallel with the improvement of the functional class of the patients. Data, in particular the possible mode of action of muzolimine after acute administration and after short-term therapy, are discussed.
The nature of the digoxin-verapamil interaction was explored "in vitro" by determining the effect of verapamil on digoxin-induced inotropism in isolated guinea-pig atria. Verapamil, at concentrations (2.10(-8)-3.10(-8)M) too low to have any significant effect on the amplitude or frequency of the basal contractile activity, reduced the inotropic action of digoxin in all experimental circumstances, i.e. in spontaneously beating atria from reserpine-treated or untreated animals, in electrically driven (at 1 Hz frequency stimulation) left atria. The results obtained suggest that a competitive antagonism exists between verapamil and digoxin. In spontaneously beating atria an apparently competitive antagonism was also observed between verapamil and ouabain. The interaction observed between cardiac glycosides and the Ca++ channel blocker suggests that Ca++ movements across the sarcolemma may influence the inotropic effect of digitalis or its toxicity.
The aim of the present work was to evaluate the possible influence of amiodarone on some basic parameters of acute oral digoxin kinetics. A single oral dose of digoxin (0.50 mg) was administered to six healthy volunteers both before and at the end of a 7-day treatment with with amiodarone. This treatment caused a clear-cut rise in peak serum digoxin levels (Cmax) from 2.92 +/- 1.09 to 5.87 +/- 1.68 ng/ml (p less than 0.005) and a decrease of the peak time (Tmax) in four out of the six subjects. The area under the serum concentration-time curve (AUC) was increased by amiodarone with a high individual variability (30.71 +/- 6.15 vs 40.63 +/- 10.04 ng X h X ml-1). Also the 72-hour recovery of the glycoside in the urine was higher (258.77 +/- 68.41 vs 357.62 +/- 62.98 micrograms; p less than 0.01), while renal clearance (Clr) was not altered. These results show that amiodarone increases digoxin bioavailability by a mechanism which appears to be independent of changes in drug elimination.
UNLABELLED: To investigate the role of the renin-angiotensin-aldosterone system in hypertension due to coarctation of the aorta (COA), upright mean arterial pressure (MAP), plasma renin activity (PRA) and plasma aldosterone (Aldo) were determined before and 90 minutes after a single oral dose of captopril (25 mg) in eight patients with COA and in fourteen with essential hypertension (EH). There was no significant difference in MAP, PRA or Aldo values between the two groups in baseline conditions. After captopril administration, MAP and Aldo decreased significantly in both groups (p less than 0.01), whereas PRA showed a marked increase in patients with COA (p less than 0.001) and no significant changes in EH patients (from 1.5 +/- 2.2 to 49.7 +/- 9.8 and from 5.6 +/- 0.9 to 8 +/- 1.5 ng/ml/3h respectively). CONCLUSIONS: 1) MAP reduction and marked renin increase after captopril in COA patients support the view that systemic hypertension in COA is, at least in part, renin mediated and 2) the evaluation of PRA after captopril could be helpful in the decision to proceed with more invasive procedures in patients with suspicious clinical features of COA or with residual post-coarctectomy hypertension.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In 37 patients with coarctation of the aorta, arterial blood pressure and ambulant plasma renin activity (PRA) were determined before and, in 15 patients, after surgical correction. The systolic blood pressure was raised in all the cases and the diastolic pressure was raised in 30 patients. Ambulant PRA was increased in 11 patients when compared with normal subjects of similar age. Twelve of the 15 operated patients had a significant decrease of systolic pressure after operation. Eight had raised PRA, and in 7 of these PRA fell to normal after operation and the blood pressure also fell; in 1 patient the decrease of PRA was unaccompanied by a fall in blood pressure. Though there was no significant correlation between the changes in blood pressure and PRA after operation it seems possible from our results that the renin-angiotensin system may be activated and contribute to the raised arterial pressure which occurs in patients with aortic coarctation.
Explore the source record for details and available documents.
A computer analysis is reported of the most significant data concerning 1624 pacemaker implantations and 1386 battery replacements. The patients were treated by endocardial stimulation with transvenous electrodes in 91% of the cases; the remainder: 9% received epicardial electrodes. The mode of stimulation was 2189 times "demand", 138 "synchronized" and 683 "asyncronous". Pacers of 13 different brands were used. At the beginning of our experience, the catheter was introduced through the superficial or profunda giugular vein: since 1969 the cephalic vein has been preferred. Epicardial electrodes were implanted via a left thoracotomy but in the most recent years the extrapleural phrenico-pericardial approach has been adopted. In a number of cases external pacemakers have been employed for permanent stimulation. The most common post-operative complications were infection (3.9%), skin erosion (2.2%), catheter rupture (3.5%), electrode dislodgement (1.7%). Such complications are becoming less frequent since 1969, due to technical improvements.
Premature atrial stimulation was carried out in 32 patients, and for each stimulus the basic cycle (A1A1), test cycle (A1A2), and the return cycle (A2A3) were analyzed. When A2A3 was plotted as the function of A1A2, a biphasic pattern, characterized by a slope phase followed by a "plateau", was observed in 25 subjects. Sinoatrial conduction time (SACT) was calculated using the Strauss method, which assumes that in the plateau A2A3 = A1A1 + SACT. Sinus arrhythmia was also determined in order to evaluate its importance in altering the results of premature atrial stimulation: it should be pointed out that when arrhythmia was marked it was impossible to calculate sinoatrial conduction time. An inverse correlation between A1A1 and the calculated SACT and between A1A1 and A2A3/A1A1 in the plateau was also demonstrated. The reliability of SACT obtained by premature atrial stimulation is discussed in relation to the results obtained and the data found in the literature.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.