Piero Cinelli

A chronobiologic study on some cardiovascular parameters

We studied the chronobiologic pattern of heart rate, R and T wave voltage, QT interval, and ST segment displacement. Premature atrial and ventricular beats obtained by dynamic electrocardiography, as well as arterial blood pressure measurements obtained by autometry, have also been studied in 131 untreated subjects (25 with hypertension, 28 with major risk factors for coronary artery disease, 9 with coronary artery disease, 37 presumably healthy and 11 shift workers). Our results show the existence of circadian rhythms in heart rate, in the duration of the QT interval and also in the voltage of R and T waves. Our data for R and T wave voltages do not completely agree with those from other authors. We demonstrated also that smoking may influence the circadian acrophase of the rhythm in R wave voltage while sleeping does not show any relationship with R and T wave voltages although it seems related to the displacement of the ST segment. We could point out only small differences in the chronobiologic behavior of patients with coronary disease and that of normal subjects, unlike the results previously reported by other authors. Our study demonstrated the existence of circadian and ultradian rhythms in premature atrial and ventricular beats as well as circadian and circaseptan rhythms in arterial blood pressure. Further studies are needed to improve our chronobiologic knowledge in order to optimize dosage and time of administration of the drugs used in the long term management of arrhythmias and hypertension.

Response of Some Haemocoagulatory and Haemorheological Variables to Maximal Exercise in Sedentary and Active Subjects

The purpose of this study was to evaluate how physical conditioning is associated with haemostatic and rheological responses to strenuous exercise. A total of 25 males, divided into two groups differing in exercise fitness (14 sedentary and 11 active), underwent exercise testing on a bicycle ergometer with an initial 25 W workload increasing by the same amount every 3 min. The following variables were evaluated before and after the test: platelet count and aggregability, plasma fibrinogen, fibrinolytic degradation products, viscometry and micro-haematocrit. Significant differences in baseline values between the two groups were found only for blood viscosity. Irrespective of the group, significantly increased values were demonstrated for all the variables, except platelet aggregability and fibrinogen levels, in response to strenuous exercise. It is concluded that the possible protective effect of exercise against cardiovascular disease does not seem to be related to changes in the haemorheological and haemostatic measures evaluated.

Low incidence of cardiac hypertrophy in essential hypertensives with no retinal changes

120 subjects, 90 hypertensives and 30 age-matched controls, were evaluated by fundoscopy and echocardiography to assess the degree of target organ involvement. The hypertensive patients were divided into 3 groups (mild, moderate, severe hypertension) according to their diastolic blood pressure levels. No significant difference was demonstrated in left ventricular mass among the 3 groups. Moreover, no relationship was demonstrated between the degree of hypertension and the severity of fundoscopic changes. Our findings indicate that patients with no retinal changes show a low probability of left ventricular hypertrophy and that patients with left ventricular hypertrophy show a high probability of retinal involvement. Our data indicate that fundoscopy is more sensitive than echocardiography in the recognition of the hypertensive disease.

Effect of age on mean heart rate and heart rate variability

Age-related changes in heart rate and in its variability might prove to be a suitable parameter to evaluate the physiological course of advancing age in human beings. We demonstrated higher mean heart rate values and increased heart rate variability in younger adult subjects. A significant direct relationship was demonstrated by linear regression equation between age and the product between mean heart rate and heart rate variability. We conclude that the analysis of these parameters may help assess the aging process of human beings.

Sleep‐wakefulness cycle and circadian variations of the electrocardiogram

Abstract A group of 11 healthy subjects aged 32–48 years was studied by dynamic electrocardiography. Electrocardiogram (ECG) was recorded on CM5 lead for 14 sec every 15 min during 24 h. All the subjects were under a different sleep‐wakefulness cycle, sleeping at different hours of the day. The time of midsleep was used to reference the chronobiologic evaluation of the parameters studied. Single cosinor analysis of the data revealed statistically significant circadian rhythms in: (a) heart rate (HR) and duration of QT interval for all the subjects studied; (b) ST segment displacement for the 2 subjects who were found to have it; (c) R and T waves voltage for 10 and 7 subjects, respectively. On the contrary, population mean cosinor analysis of the same data revealed statistically significant circadian rhythms only in HR and in the duration of QT interval. We conclude that only HR and QT interval relate to the sleep‐wakefulness schedule.

Ventricular Late Potentials in the Assessment of Mitoxantrone Cardiotoxicity

Sixteen female patients underwent signal-averaged electrocardiography and radionuclide angiography for the assessment of the resting left ventricular ejection fraction in the course of chemotherapy with mitoxantrone (MTX) for advanced breast cancer. Nine patients had received prior cardiotoxic treatments. Our findings indicate that patients treated with MTX may develop late potentials.

Effect of aging on heart rate: a chronobiological study

Abstract A group of 39 males divided into three groups according to age and with no clinical or instrumental signs of cardiovascular disease was studied by continuous 24‐h electrocardiogram recording. All the subjects were under the same sleep‐wakefulness cycle and meals schedule. Single cosinor analysis demonstrated significant circadian rhythms in heart rate for all the subjects. Multiple regression analysis revealed the existence of a significant inverse relationship between age and mesor and amplitude of the rhythm. Analysis of variance and extended Tukey test demonstrated significantly different mesors and amplitudes among the three different groups of ages. We conclude that aging is characterized by a progressive decrease in mesor and amplitude of the circadian rhythm in heart rate.

Chronobiological analysis of plasma concentrations of atrial natriuretic peptide in patients with moderate essential hypertension and in normal subjects

Abstract A group of hormones with potent diuretic/natriuretic activity, vasorelaxing properties and aldosterone secretion inhibiting action, are synthesized within the myocytes of cardiac atria and secreted by the stimulation of atrial stretch receptor. They are frequently elevated in hypertensives and may show a circadian rhythmicity in normal subjects. In the present study, to investigate the circadian pattern of ANF, we measured its plasma concentrations in a group of 12 healthy subjects and in a group of 10 patients with mild essential hypertension. None of the 10 hypertensives and of the 12 normotensives showed a significant circadian rhythm of ANF plasma concentrations. Also, we did not demonstrate a significant group rhythm for the two populations studied. Furthermore, no difference was seen in ANF plasma levels between mild hypertensives and healthy control subjects.

Muscular Blood Flow in Patients with Heart Failure

We studied reactive hyperemia in a group of patients with heart failure before and after therapy, since changes in the characteristics of muscular blood flow may influence the functional class of these patients. At the same time we evaluated some echocardiographic parameters too. When the patients improved clinically, they showed an increase in muscular blood flow at rest and in percent of fractional shortening and a decrease in peripheral vascular resistance. The reactive hyperemia did not change significantly. This fact probably depends on a maximal response to the postischemic hyperemia and represents the integrity of autoregulatory mechanisms.