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Biomedical subjects

I Simonetti

Publications and source records attributed to I Simonetti.

54 records · Page 3Linked to original sources
PubMed1986

Coronary vasodilation by nitrates is not mediated by the prostaglandin system: a quantitative cineangiographic study.

The possible role of prostaglandins in mediating large coronary artery vasodilation by nitrates was investigated by quantitative magnification coronary angiography. The effects of aspirin (1 g systemically and 100 mg intracoronary) in preventing large coronary artery vasodilation induced by intracoronary isosorbide dinitrate was investigated in 16 patients. Of these, 5 received 0.3 mg (Group 1A) and 11 received 3 mg (Group 1B) intracoronary isosorbide dinitrate, before and 15 minutes after aspirin. Relative to control, 0.3 mg isosorbide dinitrate induced a 19 +/- 9% (mean +/- SD) (p less than 0.01) and 19.5 +/- 11% (p less than 0.01) increase in coronary diameter before and after aspirin, respectively (p = NS). Changes after 3 mg isosorbide were 23 +/- 12% (p less than 0.01) and 26.5 +/- 14% (p less than 0.01), respectively, before and after aspirin (p = NS). In 10 additional patients (Group 2), the effect of the same dose of aspirin on rest coronary artery tone was assessed: changes relative to control were 0.9 +/- 5.5% (p = NS) minutes after aspirin. The intracoronary administration of 3 mg isosorbide dinitrate produced a 24.7 +/- 11% increase in coronary diameter (p = NS versus pre- and postaspirin isosorbide in Group 1B). Urinary 6-ketoprostaglandin-F1 alpha values in urine samples collected in the 8 hours before and the 8 hours after the study in five patients in Group 1B and five patients of Group 2, revealed a 36 +/- 14% (mean +/- SD) reduction in excretion of prostacyclin (p less than 0.01). These data rule out a role for prostaglandins both in mediating dilation of large coronary arteries by nitrates and in affecting their vascular tone at rest.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Dose-response scrutiny of coronary vasodilation after intracoronary verapamil in man. A quantitative cineangiographic study.

The effect of various doses of intracoronary verapamil on the diameter of angiographically normal left coronary artery segments was investigated in 22 patients with and without coronary atherosclerosis by quantitative angiography. Very low doses (50 micrograms) were given in 3 patients; doses of 250 micrograms, 350 micrograms and 500 micrograms were administered in 7, 6 and 13 patients, respectively. A single dose was administered in 15 patients, while two increasing doses of verapamil were tested in 7. The effect of verapamil was compared in each patient with that of nitroglycerin (NG; 0.6 mg), administered sublingually in all as the last step of the study. An additional group of 8 patients served as the control. These patients received 4 intracoronary injections of contrast medium without drugs and a fifth injection following 0.6 mg of sublingual NG. In the control group no significant changes in coronary artery diameter were observed following the four control injections of contrast medium, while a 18 +/- 9% increase in vascular diameter was observed following NG. When verapamil was injected a dose-dependent vasodilation was observed, which began to be significant with doses higher than 250 micrograms. Mean percent variations of coronary artery diameter relative to control were -0.2 +/- 3.6%, 4.6 +/- 5.5%, 11.4 +/- 7.5% and 19.9 +/- 10.7%, in response to verapamil doses of 50, 250, 350 and 500 micrograms, respectively. Subsequent nitroglycerin induced a 21.5 +/- 10.7% mean percent coronary artery dilation (NS vs verapamil 500 micrograms and vs NG in the control group). Thus, verapamil induced a dose-dependent coronary vasodilation which at a dose of 500 micrograms was comparable to that induced by NG. Both with verapamil and NG the smallest vessels exhibited the greatest vasodilation. It is concluded that at the doses used in this study, injection of verapamil into the left coronary artery is safe and markedly decreases tone in the large coronary arteries. This finding supports the use of verapamil in clinical conditions in which the role of coronary vasoconstriction is proven or thought to be relevant.

Adult↗
PubMed1986

Clinical application of monitoring techniques: hemodynamic monitoring.

In the diagnosis of myocardial ischemia continuous hemodynamic monitoring may contribute to detection of transient ischemia, to definition of location and to elimination of its pathogenesis, and to characterization of hemodynamic response to ischemia. It can be helpful in investigating the significance of negligible, non specific and/or short-lasting electrocardiographic changes accompanying typical anginal symptoms. Simultaneous right ventricular and left ventricular pressure monitoring gives information regarding biventricular interaction during episodes of transient ischemia: an early left ventricular dysfunction, with or without a late right ventricular impairment, a selective right dysfunction, and a simultaneous left ventricular and right ventricular impairment all represent the hemodynamic patterns associated with left, right and biventricular ischemia respectively. Monitoring of hemodynamic parameters related to myocardial oxygen consumption and the study of their changes preceding the onset of ischemia during both spontaneous and provoked episodes of ischemia, may help in identifying whether functional or organic factors or both are involved in the pathogenesis of transient ischemia in individual patients. Two principal hemodynamic patterns appear to be associated with transient ischemia: a) left ventricular and/or right ventricular impairment, usually beginning shortly before the onset of electrocardiographic changes, followed by a rapid recovery and often an overshooting, b) a sudden and sustained increase in systolic pressure and heart rate, simultaneous with the onset of ST-T changes. In both cases, the 'excitatory' pattern appears to be unrelated to pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1984

Effects of dilazep on coronary and systemic hemodynamics in humans.

The cardiovascular effects of dilazep, a new antianginal drug, were investigated in 18 patients, who underwent cardiac catheterization and coronary angiography for the evaluation of chest pain. Dilazep, 0.2 mg/kg, was injected intravenously over 1 to 2 minutes. The changes induced by dilazep in coronary tone were assessed by quantitative angiography in four patients, changes in systemic and coronary hemodynamics and blood gases in eight patients, and changes in systemic and pulmonary hemodynamics and blood gases in six. In 6 of the 18 patients the effects on hemoglobin-O2 oxygen binding were also investigated. Following dilazep administration, we observed a marked reduction of coronary resistance (six patients) (0.5 vs 1.0 mm Hg X min X ml-1, p less than 0.01) and of aortic-coronary sinus oxygen difference (seven patients) (4.6 vs 12.3 vol%, p less than 0.01), and a 23% increase in coronary diameter (four patients) (p less than 0.001). Total systemic resistance was also reduced by dilazep (six patients). Conversely, only minimal or insignificant changes were observed in heart rate (14 patients), aortic pressure (14 patients), total pulmonary resistance (six patients), myocardial oxygen consumption (six patients), double product (14 patients), blood gases (seven patients), and hemoglobin-oxygen affinity (six patients). We conclude that dilazep exerts a powerful dilating action on coronary vasculature without appreciable increase of myocardial oxygen consumption and cardiac work simultaneously with a reduction of peripheral resistance.

Adult↗
PubMed1983

Coronary vasodilation by nitrates is not mediated by the prostaglandin system: an angiographic and hemodynamic study.

The possible role of prostaglandins in mediating coronary vasodilation by nitrates was investigated in 13 patients. In nine patients (Group 1), the effects of ISDN on coronary-artery diameter and (in four of the nine) coronary sinus flow before and after administration of ASA were compared. In four additional patients (Group 2) the first ISDN administration was omitted in order to investigate the effect of ASA on resting coronary artery tone. Dosages used were 3 mg intracoronary ISDN and 1.0 g intravenous and 100 mg intracoronary ASA. Coronary artery diameter was analyzed by means of quantitative magnification coronary angiography. Coronary sinus flow was investigated by means of coronary sinus thermodilution. ASA was not able to induce significant changes in coronary artery diameter when injected before administration of ISDN or to prevent ISDN-induced vasodilation. At the coronary resistance level, ASA was not able to prevent the relative vasodilation induced by ISDN. It is concluded that coronary vasodilation by nitrates is not mediated by the prostaglandin system.

Aspirin↗
PubMed1980

Sequence of events in angina at rest: primary reduction in coronary flow.

To investigate the events that lead to acute myocardial ischemia we monitored continuously the ECG, the left ventricular (four patients) or aortic (two patients) pressure and the great cardiac vein oxygen saturation (CSO2S) by a fiberoptic catheter in six patients with frequent anginal attacks at rest. We recorded 137 transient ischemic episodes (10 with chest pain) characterized by ST-segment elevation in 28 episodes, depression in three episodes and by pseudonormalization of previously inverted or flat T waves in 106 episodes. The onset of electrocardiographic and hemodynamic changes was preceded by a large drop in CSO2S in all 135 episodes with ST-T changes in the anterior leads but not in two episodes with ST elevation on inferior leads. The fall in CSO2S, consistently followed by signs of left ventricular function impairment and never preceded by any detectable increase in the hemodynamic determinants of myocardial oxygen consumption, probably reflects a reduction in regional perfusion. Thus, a reduction in coronary flow may cause transient ischemia in patients with angina at rest. These episodes may be associated with variable, often minor electrocardiographic changes and occasionally with anginal pain.

Adult↗
PubMed1979

Management of unstable angina at rest by verapamil. A double-blind cross-over study in coronary care unit.

A therapeutic trial with verapamil, a calcium-antagonist drug, was performed in 12 patients admitted to our coronary care unit because of frequent daily attacks of angina at rest attributed to coronary vasospasm. After a 48-hour run-in period, oral verapamil 480 mg/day and placebo were administered alternately during 4 randomised 48-hour periods. Transient ischaemic attacks with ST segment elevation or depression, with or without pain, were documented by continuous electrocardiographic monitoring. The number of attacks during the run-in and 2 placebo periods were 128, 123, and 130, respectively, and 31 and 23 during the 2 treatment periods (P less than 0.006 and P less than 0.003). This drug therefore appears to be effective in the management of patients with frequent attacks of angina at rest.

Adult↗
PubMedDate not supplied

The regional distribution of adenosine-regulating enzymes in the left and right ventricle walls of control and hypertrophic heart.

The transmural distribution of the adenosine-generating enzyme 5'-nucleotidase (5'N) and of the adenosine-degrading enzymes adenosine deaminase (ADA), AMP deaminase (AMP-D) and adenosine kinase (Ado-K) were determined across the walls of left and right ventricles of control and hypertrophic rat hearts. The enzyme distribution across the left ventricle wall (but not across the right wall) of normal hearts was not uniform: 5'N activity shows its highest levels in the subepicardial and in the subendocardial regions, whereas all the other enzyme activities show their lowest levels. A similar pattern of transmural distribution was also detected in other mammalian species (ox and pig). In the experimental cardiac hypertrophy, caused by two different types of chronic cardiac overload, the levels and the profiles of transmural distribution of 5'N and ADA enzyme activities may significantly change across the rat left ventricle wall.

5'-Nucleotidase↗
PubMedDate not supplied

Changes in the transmural distribution of antioxidant enzyme activities across the left ventricle heart wall from rats fed ad libitum or food-restricted during growth and aging.

Data on vulnerability to injury and on the larger age-related accumulation of lipofuscin in the subendocardial myocardium prompted us to investigate the changes in the levels and in the transmural distribution of catalase (C), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities across the left ventricle heart wall of rats fed ad libitum a standard diet or submitted to intermittent feeding during growth and aging. Enzyme activities were assayed by standard techniques on subepicardial, midmyocardial or subendo- cardial tissue obtained by cutting the heart wall into 100-microm-thick sections at the cryostat. The levels of GSH-Px and of C (but not of SOD) activity increased with age and reached their highest values in the subendocardial region by adulthood or senescence, respectively. No effect was observed of intermittent feeding on age-related changes in enzyme levels and transmural distribution.

Journal Article↗
PubMedDate not supplied

[Clinical use of glycoprotein IIb/IIIa inhibitors].

Glycoprotein IIb/IIIa inhibitors are a new class of very powerful antiplatelet agents that act by inhibiting fibrinogen interplatelet bridges. Abciximab, tirofiban, lamifiban, and integrelin, all intravenous formulations, have been evaluated in phase II and phase III clinical trials. Although there seem to be relevant differences among drugs, their efficacy in treating acute ischemic syndromes and preventing acute complications of coronary angioplasty has been demonstrated. The major side effect has been an increase in bleeding complications. Future studies will be aimed at optimizing results and improving safety through more accurate assessment of optimal dosage and duration of infusion.

Abciximab↗