Search PubMed⌕ Search

Biomedical subjects

A Mezzetti

Publications and source records attributed to A Mezzetti.

At least 109 records · Page 6Linked to original sources
PubMed1987

Mechanism of isoproterenol-induced angina pectoris in patients with obstructive hypertrophic cardiomyopathy and normal coronary arteries.

In 14 patients with obstructive hypertrophic cardiomyopathy and angiographically normal coronary arteries, 8 with angina (group B) and 6 without (group A), the effects of intravenous isoproterenol, 2 to 4 micrograms/min, followed by intravenous propranolol, 0.2 mg/kg, were studied. An intraventricular systolic gradient less than 50 mm Hg, high-quality echocardiograms and cineangiograms and high-fidelity pressure tracings were selection criteria. Hemodynamic and metabolic variables were assessed during basal conditions, after 5 minutes of isoproterenol infusion or at angina and ST-segment depression, and 5 and 10 minutes after intravenous propranolol infusion. Isoproterenol increased the intraventricular systolic gradient more significantly in group B than in group A (102.4 +/- 8.3 vs 52.2 +/- 8.2, p less than 0.0001). Group B also had higher left ventricular end-diastolic pressure (32.5 +/- 3.9 vs 20.2 +/- 5.7), lower mean arterial pressure (69.7 +/- 3.5 vs 84.7 +/- 4.8) and a smaller increase in coronary sinus flow (176.1 +/- 9.2 vs 261.5 +/- 33.9, all p less than 0.0001), concomitant with lactate release and ST-segment depression. Propranolol promptly reversed hemodynamic and metabolic changes caused by isoproterenol, except for a further coronary sinus flow increase (from 176.1 +/- 9.2 to 219 +/- 14.2 ml/min, p less than 0.001), and heart rate decrease below basal values (57.8 +/- 7.5 vs 79.9 +/- 9.8 beats/min, p less than 0.001) in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

Effect of cholinergic agonists and antagonists on gallbladder volume in fasting man.

The effect of direct cholinergic stimulation and blockade on gallbladder volume, determined by real-time ultrasonography (RUS), was evaluated in twenty normal, fasting subjects. Eleven subjects received atropine sulphate or placebo and 9 subjects a series of 3 injection of prostigmine, bethanechol or placebo, randomly assigned, at intervals of 24 h. RUS was performed under basal conditions after fasting for 12 h and every 5 min after drug injection up to 45 min in the atropine study and up to 60 min after prostigmine and bethanechol. There was no significant variation from fasting gallbladder volume after placebo in either group. After atropine sulphate gallbladder volume at first decreased and then significantly increased. With bethanechol and prostigmine, the volume fell significantly to a trough after 30 to 35 min, and then it returned to the basal value within 60 min. It is suggested that cholinergic mediation is involved in maintaining fasting tone in the gallbladder and that cholinergic stimulation causes contraction of the gallbladder by a direct effect.

Adult↗
PubMed1987

Study of the cardiovascular effects of clenbuterol in exercise-induced asthma.

The protective effect of clenbuterol on exercise-induced asthma was studied in 14 patients with aspecific bronchial hyperreactivity. The selectivity of clenbuterol for beta 2-receptors was also studied. Patients were selected according to spirometric criteria: reduced dynamic indexes of respiratory function after exercise and, particularly, forced expiratory volume at 1 s (FEV1) decreased by at least 20% compared with initial values. A polycardiographic study was simultaneously carried out for the evaluation of systolic time intervals and polycardiographic indexes (Weissler index, Blumberger index and QT/QS2 index). After the preliminary measurements (C1), oral clenbuterol was started (0.02 mg X 2/day) and measurements were repeated after 30 (CII) and 60 days (CIII) of therapy. During treatment, physical exercise did not significantly influence the indexes of respiratory function (FEV1 decreased by 4.7 +/- 5.8 and 9.8 +/- 10.5% in CII and CIII with respect to initial values). Similarly systolic time intervals and polycardiographic indexes did not change significantly with respect to the initial values. A small increase in heart rate at rest was observed in CII (+ 7%, p less than 0.05): however, no significant changes were recorded in CIII compared with the initial values. Clenbuterol thus seems to offer an effective protection against exercise-induced asthma without the negative effects on the cardiovascular system which may arise from activation of beta 1-adrenergic receptors.

Adolescent↗
PubMed1986

Effect of cisapride on human fasting gallbladder volume: a real-time ultrasonographic study.

The effect of cisapride, a new non-antidopaminergic agent, on human gallbladder volume has been studied in nine normal subjects. In a double-blind crossover fashion, each subject was given a slow i.v. injection of cisapride and placebo after 12-h fasting. Gallbladder volume was monitored every 15 min for 90 min by real-time ultrasonography. After cisapride, gallbladder volume significantly diminished, with a mean reduction of 22.9 +/- 5%, observed 30 min after injection, whereas no significant changes were noted after placebo. A cholinergic mechanism is proposed to explain the effect of cisapride on gallbladder volume.

Adult↗
PubMed1986

Lactate release during the recovery period of pacing-induced angina in assessment of myocardial ischaemia.

Myocardial lactate (L) metabolism was tested in 27 stable angina patients during atrial pacing (AP) and in the recovery period (R) from AP-induced angina pectoris. The recovery period was assessed in order to evaluate the changes in the rate of L release and detect possible relationships with the severity of ischaemic damage. The following variables were assessed: coronary sinus blood flow (CSBF), left ventricular end-diastolic pressure (LVEDP), lactate extraction ratio (L%), lactate extraction or release rate (LR) and myocardial oxygen consumption (MVO2) at the onset of AP (AP1), during angina (AP2), and 30 s, 2 and 4 min (R1, R2 and R3) after AP ceased. At Ap2, negative L% and LR values (-39.37 +/- 43.3, -3.2 +/- 2.9) were found, in spite of a rise in CSBF (+86%, P less than 0.001). Furthermore, LVEDP showed its maximal increase in AP2 (+27%, P less than 0.001). Compared to AP2, L% resulted unchanged in R1, while LR showed a mild decrease (from -3.2 +/- 2.9 to +2.06 +/- 2.93). Lactate production was converted to extraction in R3 only. Since lactate production and release are progressively reduced with increasing severity of ischaemic damage, AP2 coronary sinus lactate release should largely arise from the less damaged areas (i.e. the outer myocardial layers) and the contribution of the more damaged areas (i.e. the inner myocardial layers) should be more limited. After AP ceases, the mild ischaemic areas should recover more rapidly than the severely ischaemic areas, where the damage only declines, leading to a temporary increase in lactate production and release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Physiology of interdigestive motor activity in man].

Aim of this work has been to investigate the pattern of interdigestive motility from the esophagus to the duodenum. Six human subjects have been studied by means of a manometric probe. The results are very similar to those described elsewhere, and show that a cyclic motor activity spreads down from the esophagus to the duodenum and that a district control of gastrointestinal motility exists.

Adult↗
PubMed1984

Catecholamine release in coronary sinus during vasospastic angina induced by ergonovine.

In seven patients with spontaneous angina and three control subjects, aortic and coronary sinus norepinephrine and epinephrine were assessed. Samples were taken in basal conditions and during ergonovine test in coronary sinus and aorta. The behaviour of some hemodynamic parameters as heart rate, blood pressure, left ventricular end diastolic pressure and coronary sinus flow was also studied. Resting myocardial norepinephrine and epinephrine flux was similar for both groups. In ischemic patients ergonovine induced a coronary spasm accompanied by an evident reduction of coronary sinus flow and a slight increase in arterial epinephrine and norepinephrine concentrations. However, a significant decrease in the net myocardial norepinephrine and epinephrine release was evidenced. After ergonovine, not significant changes in norepinephrine and epinephrine concentration and release resulted in control subjects. The increase in peripheral catecholamine concentrations found in ischemic patients during ergonovine test could represent a reflex activation of sympathetic activity induced by an ischemia dependent ventricular mechanical disfunction. The decrease in myocardial catecholamine release during angina could be justified by sequestration of epinephrine and norepinephrine in ischemic areas induced by vasospasm or reflex inhibition of cardiac sympathetic tone.

Adult↗
PubMed1982

Hemodynamic and metabolic effects of nitroglycerin ointment in pacing-induced angina pectoris.

Hemodynamic and metabolic effects of nitroglycerin ointment (40 mg nitroglycerin) were tested on 15 patients with clinical evidence of stable angina. Basal value (B) and atrial pacing (AP)-dependent changes were evaluated before and 30 min after ointment administration. After treatment tension time index (TTI) basal value showed a 19% reduction (p less than 0.05). Compared to the control a lesser AP-dependent increase was also noted (27%, compared to 45%; p less than 0.005). According to TTI reduction, MVO2 showed an evident decrease both in basal conditions and during AP (21% and 29.6%, respectively). On the contrary, diastolic pressure time index (DPTI) does not result significantly influenced by the treatment. Consequently, DPTI/TTI ratio increase is largely the result of TTI reduction, which is well correlated to myocardial oxygen demand. Coronary sinus blood flow decrease (16% and 27% under basal conditions and during AP, respectively) confirms that the therapeutic efficacy of the ointment does not result from an increase in myocardial oxygen supply. Finally, during AP nitroglycerin ointment resulted in a significant decrease in myocardial lactate release (L% mean value ranges from-17.5% to 3.4%; p less than 0.001). Such an improvement probably reflects a primary influence of the drug on the extracoronary vascular bed.

Adult↗
PubMed1982

[Importance of metabolic disorders and endocardial viability ratio in the prognosis of open-heart operations. Experimental study of the pig heart protected by potassium cardioplegia in hypothermia].

The aim of this study was to investigate the protective efficacy of potassium cardioplegia in general moderate hypothermia, in five pigs, after 90 minutes of myocardial ischemia induced by extracorporeal circulation (ECC) and aortic clamping. The behaviour of subendocardial supply demand ratio (DPTI/TTI), of CSBF (coronary sinus blood flow) and numerous hemodynamic parameters was evaluated in addition to lactate myocardial metabolism changes, at rest, after 90 minutes of total ECC and during a 60 minutes reperfusion period. The reperfusion period included two phases: during the first (15-20 minutes) the animals were in ECC with unclamped aorta; spontaneous circulation was instituted during the second one (40 minutes). A marked increase in CSBF was observed at aortic clamp removal during the first phase (post ischemic reactive hyperemia). Coronary sinus lactate release was also noted, probably due to wash-out of previously sequestered acid metabolites during aortic clamping (90 minutes). At the onset of the second phase a depressed left ventricular performance and low DPTI/TTI values were shown. A rapid return (20 minutes) to normal values of this parameter was then noted. DPTI/TTI normalization results strictly correlated to the progressive improvement in myocardial performance. Hypothermic potassium cardioplegia seems therefore to prevent the irreversible myocardial damage and favour a fast recovery of cardiac function.

Animals↗
PubMed1980

[Cardiac metabolism in angina patients before and after aorto-coronary bypass].

The haemodynamic indices proposed by Buckberg et al. have been used to evaluate total coronary flow and its distribution to the subendocardial tissue. The following conclusions were drawn from the data obtained in humans and in experimental pathology: 1) in regional ischaemia (angina, myocardial infarction), the DPTI/TTI ratio expresses the degree of subendocardial hypoperfusion with fair approximation, although it has some theoretical limitations, 2) in total myocardial ischaemia, as occurs during ECC, the index provides an accurate picture of the subendocardium and a useful idea of the real effectiveness of the means of myocardial protection.

Angina Pectoris↗