Marco Michieletto

University of Padova, Padua, Veneto, Italy

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Publications (10)21.02 Total impact

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    ABSTRACT: Objective: In this study, we tested the hypothesis that sympathetic over-activity may cause metabolic abnormalities and affect left ventricular (LV) structure and mass early in life. Subjects and setting: The study population consisted of 111 healthy adolescents and young adults living in Tecumseh, Michigan (USA). Main outcome measures: Correlations of LV mass and structure with several clinical variables in relation to the activity of the sympathetic nervous system. Methods: Power spectrum density estimates of heart rate variability were calculated with an auto-regressive method, and subjects were divided by cluster analysis into two groups according to low-frequency and high-frequency components. LV data were obtained by echocardiographic assessment. Results: Subjects with signs of sympathetic over-activity (n = 38, group 1) had higher heart rate, blood pressure (BP), waist/hip ratio and cholesterol levels than the rest of the group (n = 73, group 2). In group 1 subjects, insulin emerged as the strongest univariate correlate of interventricular septum and posterior wall thicknesses (P <0.001 for both) and of LV mass (P = 0.009). These relationships remained significant when body mass index was accounted for. By contrast, the marginal univariate relationship with diastolic BP did not remain significant in multivariate analysis. In group 2 subjects, BP was strongly correlated with LV wall thickness and mass both in univariate (P values from 0.03 to <0.001) and multivariate analyses, while insulin was not. The interactive effect of sympathetic activity and insulin on echocardiographic data was confirmed by multivariate analyses performed in the subjects grouped together (P values from 0.02 to 0.001 for the sympathetic activity × insulin interaction term). Conclusions: In young subjects with heightened sympathetic activity and initial metabolic abnormalities, insulin is a strong determinant of LV wall thickness and geometry, while in subjects with normal autonomic nervous system activity, the main determinant of left ventricular size is the haemodynamic load.
    Full-text · Article · May 2000 · Journal of Hypertension
  • P. Palatini · S. Nesbitt · L. Krause · O. Vriz · S. Majahalme · M. Michieletto · S. Julius

    No preview · Article · Jan 1999

  • No preview · Article · Jan 1998
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    Full-text · Article · Apr 1997 · American Journal of Hypertension
  • Del Torre M · P Mormino · E Roman · M Michieletto · P Palatini
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    ABSTRACT: BACKGROUND: It has been claimed that isolated systolic hypertension (ISH) in the elderly is not a sustained condition but a short-lasting increase in office systolic blood pressure magnified by arterial stiffness. DESIGN: Office and ambulatory blood pressures werecompared at baseline and after 3 months of observation of young and elderly subjects with ISH. METHODS: The study was carried out in 39 young (mean age 27.1+/-9.8 years) and 37 elderly patients (mean age 72.5+/-5.7 years). Office blood pressure was defined as the mean of six readings. All subjects underwent two non-invasive 24 h blood pressure monitorings performed 3 months apart and echocardiography (n = 50). RESULTS: The difference between office and mean 24 h systolic/diastolic blood pressure was 27.9/8.2 mmHg in the young and 18.9/6.9 mmHg in the elderly patients (P < 0.01 for systolic blood pressure). Twenty-four-hour (P < 0.001), daytime (P = 0.001) and night-time (P < 0.001) systolic blood pressures were higher in the elderly and the difference between daytime and night-time systolic blood pressure was greater in the young (P < 0.05). Office and ambulatory heart rates were significantly higher in the young subjects. The elderly patients showed a greater left ventricular wall thickness ( P = 0.005 for posterior wall; P < 0.005 for septum), relative wall thickness (P = 0.01) and left ventricular mass index (P = 0.001) and impaired left ventricular filling rate ( P = 0.05), whereas systolic performance and stroke volume were no different in the two groups. Due to the higher heart rate, cardiac output was greater in the young (P = 0.03). CONCLUSION: These data show that larger differences between office and ambulatory systolic blood pressure are not unique to elderly patients with ISH. Increased ambulatory blood pressure levels and a decreased nocturnal blood pressure fall were associated with left ventricular structural and functional abnormalities in the elderly subjects.
    No preview · Article · Jan 1997 · Blood pressure monitoring
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    ABSTRACT: The effects of large doses of anabolic steroids on 24-hour blood pressure, cardiac structure and function, and lipid profiles were studied in 10 body builders using anabolic steroids and 14 body builders who did not use steroids (control subjects). All subjects underwent noninvasive 24-hour blood pressure monitoring, echocardiography, Doppler analysis of transmitral flow, and analysis for lipoprotein and gonadotropin levels. Anabolic steroid users were studied at the end of a steroid cycle and after a period of withdrawal. Average 24-hour blood pressure was similar in the two groups, but anabolic steroid users exhibited a smaller pressure reduction during sleep than did nonusers. This finding was present both at the end of treatment and after the period of withdrawal. Echocardiographic dimensional and functional indexes did not differ substantially between anabolic steroid users and the nonusers, and were similar in anabolic steroid users during use and after withdrawal. Anabolic steroid users also had higher LDL and lower HDL cholesterol levels than nonusers; Lp(a) was higher in nonusers, although this difference did not attain the level of statistical significance. These differences were more striking at the end of the treatment period. The results of this study show that chronic anabolic steroid intake causes an abnormal 24-hour blood pressure pattern, characterized by a flattening of the diurnal curve, and minor changes of the dimensional echocardiographic parameters.
    No preview · Article · Dec 1996 · The Journal of Clinical Pharmacology
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    ABSTRACT: To compare endocardial and midwall measurement of left ventricular fractional shortening in assessing cardiac systolic function in hypertension. Seventeen hypertension clinics in northeast Italy. Left ventricular endocardial fractional shorteningcircumferential stress relationship versus midwall shortening-stress relationship in the subjects divided according to relative wall thickness (RWT) and left ventricular mass indexed by body surface area. Borderline-to-mild hypertensives [n = 635, aged 33 +/- 0.3 years (mean +/- SEM), office blood pressure 146 +/- 0.4/94 +/- 0.2 mmHg (means +/- SEM)] in the Harvest Study and 50 normotensive controls with similar age and sex distributions. Blood pressure was measured by 24 h ambulatory monitoring. Left ventricular dimensional and functional indices were assessed by M-mode echocardiography. In the subjects divided into quintiles of RWT, the left ventricular shortening-stress relationship was increased in a parallel fashion when calculated by endocardial and by midwall measurements for RWT < or = 0.35. Instead, for greater RWT values (> or = 0.37) endocardial measurement constantly gave large values than did midwall measurement. Both the endocardial and the midwall shortening-stress relationships progressively decreased with increasing RWT. However, the endocardial shortening-stress relationship remained greater than normal at any RWT, whereas the midwall shortening-stress relationship was decreased for RWT > or = 0.37. In a multiple-regression analysis RWT was the most potent predictor of the endocardialmidwall shortening difference, left ventricular mass and 24 h systolic blood pressure being the second and third most potent predictors. We found a parallel increase in indices of cavity emptying and of myocardial contractility in mild hypertensive subjects with normal left ventricular geometry. When the RWT is increased, ejection phase indices may be normal in the presence of decreased myocardial contractility.
    No preview · Article · Sep 1996 · Journal of Hypertension
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    ABSTRACT: To evaluate the relationship of coffee use, smoking, physical inactivity, alcohol intake and overweight with casual and ambulatory blood pressure in a large population of borderline to mild hypertensive subjects. Six hundred and thirty men with a mean (+/- SE) age of 33 +/- 0.4 years (range = 18-45 years) and a mean office blood pressure of 146 +/- 0.4/94 +/- 0.2 mm Hg, participating in the multicentre HARVEST study, were divided into three categories according to: coffee consumption (0 cups, 1-3 cups, > 3 cups/day), number of cigarettes smoked per day (0, 1-10, 11-20), degree of physical activity (no activity, regular training, competitive activity), alcohol intake (no alcohol, < 50 g, > or = 50 g/day) and body mass index (tertiles). All patients underwent non invasive ambulatory blood pressure monitoring with either the A&D TM-2420 model 7 or the Spacelabs 90207 monitor. Moreover, 24-hour urine collection was made for epinephrine and norepinephrine assessment (n = 611). Twenty-four-hour systolic blood pressure was higher in the coffee drinkers than the nondrinkers (+2.6 mm Hg in the moderate drinkers). Instead, 24-hour diastolic blood pressure was mainly influenced by overweight (3.2 mm Hg difference between the low and high BMI tertiles) and physical inactivity (3.2 mm Hg difference between the sedentary men and the athletes). Generally, the association of the above factors was stronger with ambulatory than with office blood pressure, whereas alcohol intake was only related to office diastolic blood pressure. However, in a multivariate regression analysis alcohol use did not show an independent effect on either office or ambulatory blood pressure. Smoking showed a different effect on office and ambulatory blood pressure. In fact, office blood pressure was higher in the nonsmokers, while 24-hour blood pressure was higher in the smokers. Smoking, coffee and physical inactivity were associated with sympathetic overactivity, as documented by increased urinary catecholamines output. The results of the present study indicate that overweight and behavioural factors affect 24-hour blood pressure to a larger extent than office blood pressure does. This is likely to be due to their effect on the sympathetic nervous system activity, which would enhance the blood pressure response to daily life stressors.
    No preview · Article · Aug 1995 · Giornale italiano di cardiologia
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    ABSTRACT: The effect of semi-supine long lasting exercise to exhaustion [61 (SD 10) min] on left ventricular systolic performance was studied by echocardiography in 16 young healthy volunteers. During the incremental phase of exercise, the ejection fraction increased from 65.2 (SD 4.1)% to 80.1 (SD 4.8)% (P < 0.0001), then it levelled off up to the end of exercise [81.7 (SD 4.4)%, P < 0.0001 vs rest]. During recovery, the ejection fraction rapidly and steadily decreased to a value similar to that at rest [66.1 (SD 5.0)%, n.s.). A similar pattern was shown by the systolic blood pressure/end-systolic volume coefficient, which rose from 3.2 (SD 0.8) to 7.5 (SD 2.7) (P < 0.0001) in the initial phase and subsequently did not change until the end of exercise [7.0 (SD 2.2), P < 0.0001 vs rest], to fall sharply after the cessation of exercise [2.9 (SD 1.1) at the 10th min, n.s. vs rest]. Exercise and recovery indices of left ventricular performance were not correlated with exercise duration, maximal heart rate and increase in free fatty acids. The present results indicated that, after the initial increase, left ventricular performance remained elevated during prolonged high intensity exercise and that conclusions on exercise cardiac performance drawn from postexercise data can be misleading.
    No preview · Article · Sep 1994 · European Journal of Applied Physiology and Occupational Physiology

  • No preview · Article · Dec 1993 · Journal of Hypertension