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Biomedical subjects

M Chiariello

Publications and source records attributed to M Chiariello.

At least 289 records · Page 16Linked to original sources
PubMed1985

Non-invasive evaluation of the isovolumic relaxation period during dynamic and isometric exercise.

The purpose of the study was to evaluate non-invasively the response of the isovolumic relaxation period to different types of exercise--dynamic supine bicycle exercise (DSBE) and handgrip (HGP), in a selected healthy population. From simultaneous echo-polygraphic recordings, obtained in 30 young subjects at rest, during submaximal DSBE, during one minute of HGP (75% of maximal heart rate) and in the recovery period, the true isovolumic relaxation period (IRP) was determined. Systolic (SBP) and diastolic (DBP) blood pressure, aortic closing pressure (AoCP) and heart rate (HR) were also recorded. HR increased more markedly in DSBE (delta HR = +85% at peak load) than in HGP (delta HR = +29% at peak), while a greater rise of DBP (delta DBP = +25%) was observed in HGP. IRP shortened at both exercises as the workload progressively increased, with a maximum decrease by 54% in DSBE and by 42% in HGP. Moreover, at both exercises, an exponential correlation between IRP and HR was found. Correlating IRP with HR and AoCP by multiple regression analysis, it was found that IHP in HGP was equally affected by HR and AoCP, while during DSBE heart rate had a greater influence than AoCP.

Adolescent↗
PubMed1984

Systolic and diastolic time intervals during spontaneous angina.

In 5 patients who suffered spontaneous angina during cardiac catheterization, aortic pressure and electrocardiographic lead (V5) were recorded at rest, at the onset of anginal pain, 5 and 10 min after 0.6 mg sublingual nitroglycerin (NTG). Heart rate, systemic arterial pressure, systolic, and diastolic time intervals were measured. Heart rate and systemic arterial pressure rose significantly immediately after the onset of angina and declined progressively within 10 min from NTG administration. Preejection period did not change during angina, while left ventricular ejection time and electromechanical systole lengthened. As a consequence, diastolic time, expressed as percent of cardiac cycle, shortened sharply. All parameters considered went back to basal values within 10 min from NTG administration, and were preceded by relief or reduction of anginal pain. We concluded that a fall in diastolic time, secondary to a prolongation of electromechanical systole occurring during angina, may further increase the degree of ischemia resulting in a vicious cycle than can be interrupted by NTG administration.

Angina Pectoris↗
PubMed1984

Adrenergic activity as a modulating factor in the genesis of myocardial hypertrophy in the rat.

Sprague Dawley male rats (200-220 g) were subjected to a long-term treatment with low doses of catecholamines in an attempt to assess the effect of the adrenergic stimulation on ventricular weights, hemodynamics, and hydroxyproline content in the myocardium. Data are presented indicating that both exogenous catecholamines (i.e., isoproterenol) and endogenous catecholamines (released from tyramine) are able to bring about a degree of myocardial hypertrophy associated with a significant increase in the ventricular concentrations of hydroxyproline, without affecting hemodynamic parameters (blood pressures and heart rate). Thus the modulation of sympathetic tone in the genesis of cardiac hypertrophy is demonstrated, and a direct effect of the catecholamines on cardiac cells is postulated which is independent of hemodynamic changes.

Animals↗
PubMed1984

Sick sinus syndrome: the role of hypervagotonia.

A 58-year-old man with persistent symptomatic sinus bradycardia (52 beats/min) showed a markedly prolonged postpacing pause (3240 msec) after atrial pacing at a cycle of 840 msec. In addition, Wenckebach block occurred following atrial pacing at a cycle length of 700 msec. After atropine (2 mg) postpacing pauses returned to normal value and type 1 second-degree AV block completely reversed to 1:1 AV conduction until paced rates greater than 140/min. It may be that in some patients marked and persistent vagal overactivity may predispose to "intrinsic" sinus node dysfunction; in later stages, sinus node function may paradoxically result unaffected by changes in autonomic tone.

Heart Block↗
PubMed1984

Effect of experimental infarct on the mortality rate in alloxan-diabetic rats.

The authors report the wide mortality observed in alloxan diabetic rats infarcted with large doses of isoproterenol. The experimental data are in line with the results of clinical studies testifying that the diabetic disease involves the cardiovascular system and affects the prognosis of myocardial infarct. These experiences do not permit to define the direct mechanism(s) responsible for the high mortality in diabetic infarcted rats over controls (diabetic not infarcted); however these results give rise to a discussion on the following topics: 1. The damage of intramural coronary vessels as a cause of depressed cardiac contractility in diabetic rats. 2. The role of reduced plasmatic levels of insulin in depressing myocardial performance in alloxan diabetic rats. 3. The hyperglycaemia-provoking effect of isoproterenol as a contributing factor in the death of diabetic rats. 4. The possible direct action of diabetogenic doses of alloxan on the myocardium.

Alloxan↗
PubMed1984

Long-term protection of ischaemic myocardium by nitroglycerin ointment.

To assess whether the reduction in ischaemic injury during acute myocardial infarction induced by nitroglycerin (NTG) results in a decrease in tissue necrosis, 96 rats were assigned to two groups. The first group (n = 34) was sham-operated. The second group of 62 rats was randomised in a ratio of 2:1 into control (n = 43) and treated (n = 19) subgroups following coronary artery occlusion. Treated animals received an application of 2% NTG ointment every 8 h immediately post-occlusion. All rats were killed 48 h after coronary artery occlusion and total creatine kinase activity (CK) of the left ventricle (LV) was measured. Infarct size calculated by CK depletion was 65.2 +/- 14.3% (mean +/- SD) of LV in control rats, and 51.6 +/- 14.0% of LV in NTG-treated (p less than 0.02). In a further series of 46 rats with coronary occlusion, the area of infarcted myocardium 21 days post-occlusion was assessed by planimetry on histological sections. In rats with control occlusion (n = 22), the extent of infarction was 30.6 +/- 4.8% of LV, and in NTG-treated rats (n = 24) it was 16.2 +/- 5.8% of LV (p less than 0.001). The amount of scar tissue in the infarcted myocardium 21 days post-occlusion was also determined by measuring LV hydroxyproline and collagen content in an additional 32 rats randomly assigned to a control (n = 11), a NTG-treated (n = 9) and a sham-operated group (n = 12).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Nonparoxysmal atrioventricular junctional rhythm. A clinical and electrophysiologic study.

The patient, a 74-year-old man, developed a persistent nonparoxysmal junctional accelerated rhythm at rate of 60-75 beats min-1 because of chronic depressed sinus node function. Intravenous atropine resulted in no change of junctional pacemaker rate but i.v. isoproterenol significantly accelerated it suggesting that autonomic neural imbalance might underlie the mechanism of nonparoxysmal junctional rhythm. Intravenous verapamil (10 mg) induced no change in the junctional pacemaker rate and postpacing pauses suggesting that the slow inward current did not play an important role in the nonparoxysmal junctional rhythm.

Aged↗
PubMed1984

Diastolic time during exercise in normal subjects and in patients with coronary artery disease. A plethysmographic study.

Percent diastole (%D) was evaluated at rest and during effort (submaximal upright exercise) in 13 normal subjects and in 14 age-matched patients with coronary artery disease (CAD). Systolic time intervals were also simultaneously recorded by using the thermistor pulse transducer. At rest, in both groups, a positive linear regression was found between %D and cycle length (RR) (%D = 19.1 + 0.044RR, r = 0.83 in normals; %D = 21.2 + 0.044RR, r = 0.88 in CAD). During effort, while in normals no correlation was found between %D and RR values, in CAD patients %D and RR were linearly related (%D = -12.81 + 0.087RR, r = 0.67). These results prove that diastolic time is differently affected by the exercise in the two examined groups and that in CAD patients an abnormal reduction of %D occurs during stress test.

Adult↗
PubMed1984

Postural changes and isosorbide dinitrate. A polygraphic study in patients with coronary artery disease.

Sitting or orthostatic positions and trinitrine-like drugs reduce venous return. We focused on the non-invasive assessment of postural-induced cardiovascular stress and isosorbide dinitrate (IDN) induced changes in 8 male patients with coronary artery disease (CAD), using polygraphic recordings by means of a Thermistor Pulse Transducer. The pre-ejection period (PEP) is sensitive to reduced preload and to the positive inotropic state of the myocardium. In addition, the % diastole (RR interval--electromechanical systole/RR interval) has been recently demonstrated to be correlated to coronary perfusion in CAD patients. We observed that IDN in clinostatism and the sitting position reduced preload (longer PEP) with increased heart rate (HR) and did not affect % diastole. In orthostatism, while controls showed an increased HR and prolonged PEP, the HR was higher after IDN, with a fall in PEP and a significant decrease in % diastole. We ascribed this change to adrenergic stimulation by the hypotensive actions of IDN (lowered mean blood pressure) in orthostatism and with a fall in coronary perfusion. Caution should be taken in CAD patients when postural stress could occur during IDN treatment. Moreover, polygraphic studies can be useful to detect individual responses to nitrates and serial recordings could be employed to assess late responses to chronic management with IDN.

Analysis of Variance↗
PubMed1984

Effects of long-term molsidomine treatment versus isosorbide dinitrate and placebo on exercise tolerance in stable angina.

A single-blind study (n = 59) was performed to assess the effect of long-term (4 week) orally administered molsidomine (2 mg 4 X daily), isosorbide dinitrate (10 mg 4 X daily), and placebo on exercise tolerance performed on the bicycle ergometer by patients with stable angina on effort and with significant coronary artery disease. Isosorbide dinitrate had similar effects to placebo, both failed to modify the pressure-rate product, the sustained work load, and the ST segment depression, but slightly decreased, although not significantly, the incidence of angina. Although not affecting the pressure-rate product and the mean blood pressure, molsidomine decreased significantly the ST segment depression (p less than .05). In conclusion, by markedly reducing preload and because of its long-lasting effect (up to 6 h), the new vasodilator drug molsidomine plays a useful role in the long-term management of stable angina on effort.

Angina Pectoris↗