Biomedical subjects

U Guiducci

Publications and source records attributed to U Guiducci.

5 recordsLinked to original sources

PubMed1992

Sinus node function in hyperthyroid patients.

We have studied the electrophysiology of the sinus node and the role of the autonomic nervous system on sinus node function in 8 thyrotoxic patients of both sexes, 37.5 +/- 4.3 (mean +/- SE) yr old. The resting heart rate (RHR), the sino-atrial conduction time (SACT), and the sinus node recovery time (SNRT) were measured in the untreated condition (basal), after sympathetic blockade with propranolol 0.2 mg/kg body weight (BW) i.v. infusion, and after complete autonomic blockade with the additional administration of atropine 0.04 mg/kg BW i.v. bolus. 1) In the thyrotoxic patients the RHR was higher [117 +/- 6 beats per min (bpm)] than in 20 normal subjects (73 +/- 1 bpm, P less than 0.001), whereas the SACT and SNRT values were not different. 2) After sympathetic blockade with propranolol, the RHR decrement and SACT increase were greater in the hyperthyroid patients than in normal subjects, whereas there was no difference in SNRT values between the two groups. 3) In the thyrotoxic patients the complete autonomic blockade reestablished the electrophysiological parameters to values similar to those observed in basal condition. In conclusion, in thyrotoxic patients the intrinsic activity of the sinus node is increased. It appears that this is a direct consequence of thyroid hormone excess, rather than an effect of extrinsic influences exerted by the autonomic nervous system on sinus node activity.

Adolescent↗

PubMed1990

[Effects of hypertrophy on cardiac systolic and diastolic performance in athletes with mild hypertension].

Aims of the study has been the evaluation of morphological and functional aspects of left ventricle in subjects undergoing mild hypertension and sport adaptation effects. These evaluations have been carried out by Echo-Doppler both at rest and during sharp increase in after load induced by isometric stress. Together with the morphological parameters represented by mass index and by radius to thickness ratio, we have studied stroke volume and transmitral flow pattern assessing the maximum flow velocity during rapid filling phase (E), during atrial contraction phase (A) and their ratio (E/A). We have studied 31 male subjects from 39 to 60 (average 47) exercising twice or three times a week (in the main, aerobic sports such as road cycling). They were subdivided into two groups, the first included 16 subjects with mild hypertension (AP = 155 +/- 9/97 +/- 5 mmHg) the second included 15 normotensive subjects without known pathologies, comparable for age and body surface (AP = 125 +/- 15/77 +/- 10 mmHg). Hypertensive subjects exercising regularly, showed a mass index (164 +/- 42 g/m2) significantly higher than the controls (139 +/- 35 g/m2, P less than 0.01) but they ke a normal filling pattern at rest and similar stroke volume values. During isometric exercise instead, the velocities of E and A waves showed a different trend in the two groups with a higher reduction in E/A ratio in hypertensive subjects. The per cent decrease in this ratio turned out to be 15% in the control group and 33% in hypertensive subjects (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Comparison of dilevalol and enalapril administered once daily for mild hypertension.

This was a multicenter, randomized, double-blind, parallel-group study of the efficacy and safety of dilevalol, 200 mg (n = 86), compared with enalapril, 20 mg (n = 92), administered once daily to patients with mild hypertension. Three weeks of placebo washout were followed by 4 weeks of comparative treatment. Beginning with the first week of treatment, both drugs substantially decreased blood pressure from baselines of approximately 160/100 mm Hg. Decreases in systolic pressure were comparable throughout treatment, but dilevalol tended to have a greater effect on diastolic pressure. At the end of double-blind treatment, average decreases in blood pressure with dilevalol and enalapril were 16/13 and 16/11 mm Hg supine and 15/13 and 15/10 mm Hg standing (p = 0.03 for between-group comparisons of standing diastolic pressure). More dilevalol- than enalapril-treated patients achieved a diastolic pressure less than 90 mm Hg; 73 vs 55% (p = 0.02) supine, and 69 vs 43% (p less than 0.01) standing. The safety profiles of the 2 drugs were comparable. The incidence of adverse effects was low, and few patients discontinued treatment. Headache and gastrointestinal discomfort were reported in both groups. Average postural changes in blood pressure were similar to baseline. Electrocardiographic changes were rare and not treatment related. Changes in laboratory test results were minor. Heart rate decreased modestly with dilevalol relative to enalapril (6 vs 2 to 3 beats/min; p less than 0.01), but no bradycardia was observed.

Adult↗

PubMed1988

The effect of diltiazem, a calcium channel-blocking drug, on cardiac rate and rhythm in hyperthyroid patients.

Tachycardia and tachyarrhythmias are frequent in patients with thyrotoxicosis, especially in the elderly. Since myocardial calcium uptake is increased in thyrotoxic rats, the efficacy of the calcium channel-blocking drug diltiazem in decreasing heart rate and the incidence of arrhythmias was evaluated in 11 hyperthyroid patients. All patients were studied with a 24-hour Holter monitor prior to the beginning of sole diltiazem therapy (120 mg given every eight hours), on the tenth day of therapy, and five days after therapy was discontinued. Heart rate significantly decreased by 17% during diltiazem treatment (96.5 +/- 3.7 systoles/min vs 79.9 +/- 3.2 systoles/min [mean +/- SE]) and returned to baseline values five days after the therapy was discontinued (100.7 +/- 3.4 systoles/min). Similarly, the number of premature ventricular extrasystoles per hour was significantly decreased (18 +/- 7 vs 2 +/- 1). In three patients, asymptomatic bouts of supraventricular tachycardia, paroxysmal atrial fibrillation, or ventricular tachycardia disappeared during diltiazem therapy. These findings suggest that calcium-blocking drugs may be extremely useful as adjunctive therapy for thyrotoxicosis in the presence of angina, congestive failure, and tachyarrhythmias.

Adult↗

PubMed1977

[Enzymatic assessment of the area of necrosis. I. Diagnosis and quantitative evaluation of acute myocardial infarct by means of MB creatine kinase isoenzyme. Comparison with deduced from creatine kinase activity].

On the purpose of specifying more and more the peculiarity of the isoenzymes MBCK in regard to enzyme CK, in the diagnosis as well as in the quantitative evaluation of myocardial infarction, we examined 34 patients hospitalized in U.C.I.C. The curves of the MBCK and CK were obtained through samples taken every 2-3 hours still the 12th hour, after the enzymatic concentration have exceeded the normal level and successively every 4 hours till the enzymatic activity regains its limits. The values of I.S.MBCK and I.S.CK were compared and we obtained two correlations based on the enteric work (r = 0.79) or on selected cases (r = 0.96). We conclude, for the major practicality and usefulness of measurement of MBCK in the evaluation of size, because this measurement can be obtained on the total enumeration of cases of myocardial infarction, not takine into consideration all those factors which could produce an increase of CK; moreover the MBCK is able to show the extension of myocardial infarction that would not be detectable with CK.

Aged↗