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[Early alterations of adrenergic cardiac function in Parkinson's disease].

INTRODUCTION: Myocardial sympathetic (adrenergic) function is significantly affected in patients with idiopathic Parkinson's disease (PD) as is deduced from the cardiac scintigraphy evaluation with 123I-metaiodobenzylguanidine (123I-MIBG). PATIENTS AND METHODS: In the present study, 60 patients with PD were studied compared to 17 normal subject without neurological disease. The clinical parameters evaluated were severity of the condition (measured by Hoehn and Yahr Scale), vegetative manifestations, development time and use and type of medication taken. Myocardial adrenergic function was analyzed by imaging with 123I-MIBG. Early (15 min) and delayed (4 h) images of the anterior view were obtained after injection of 123I-MIBG. Qualitative and semiquantitative 123I-MIBG uptake was quantified by calculating a heart-to-mediastinum (H/M) ratio. RESULTS: We found a significant decrease of H/M ratio in patients with PD as compared with controls (p < 0.01) independently of development time, severity of the condition, use of medication or vegetative manifestations. CONCLUSIONS: There is an important noradrenergic alteration in PD, that can be detected from early stages and does not exist in other parkinsonisms caused by a different pathogenic mechanism.

3-Iodobenzylguanidine↗

Does hypotension during dobutamine stress echocardiography correlate with anatomic or functional cardiac impairment?

The development of hypotension during various exercise stress tests has been correlated with the presence of multivessel coronary artery disease and impaired left ventricular contractility. Hypotension may also occur during dobutamine stress echocardiography; however, its anatomic and functional significance remains unknown. As part of an ongoing study of restenosis, dobutamine stress echocardiography and diagnostic cardiac catheterization were performed on the same day in 105 outpatients approximately 6 months after percutaneous coronary revascularization (balloon angioplasty or directional coronary atherectomy) to determine the anatomic and functional significance of dobutamine-induced hypotension. Dobutamine was infused in stepwise increments to a maximum rate of 30 micrograms/kg/min. Hypotension was defined as a reduction in systolic blood pressure of > or = 15 mm Hg. Anatomic abnormalities were defined by quantitative coronary angiography and functional abnormalities by digitized two-dimensional stress echocardiography. Clinical, angiographic, hemodynamic, and electrocardiographic data underwent multivariable regression analysis to determine their ability to predict independently the development of dobutamine-induced hypotension. Dobutamine-induced hypotension was not associated with the presence of severity of coronary artery disease or with echocardiographic wall motion abnormalities. Univariable predictors of stress-induced hypotension included high baseline systolic blood pressure, advanced age, and high left ventricular ejection fraction. Only a high baseline systolic blood pressure contributed independent predictive information in multivariable stepwise logistic regression analysis. Therefore, the development of hypotension during dobutamine stress echocardiography, unlike that during traditional exercise stress tests, is not associated with the presence of significant coronary artery disease or left ventricular dysfunction.

Age Factors↗

Mechanisms of impaired cardiac function by vasopressin.

The mechanisms by which elevated levels of vasopressin (ADH) in man and animals cause serious myocardial dysfunction, evidenced by arrhythmias, reduction in cardiac output and coronary blood flow, are not settled. Experiments were conducted in 16 isolated working left ventricles to examine their metabolic and hemodynamic responses to the infusion of vasopressin and the combination of vasopressin and epinephrine. Contractile performance was evaluated by analysis of positive dP/dt, contractile element velocities, and ventricular work-curves using stroke work/end-diastolic pressure. Relaxation parameters, including negative dP/dt and the early diastolic relaxation time constant, were also studied. Coronary blood flow was reduced 22% or less by vasopressin while cardiac output was maintained at a constant level. Myocardial oxygen consumption, lactate and potassium balances were determined from arterial and coronary sinus concentrations. Vasopressin produced myocardial dysfunction indicated by decrements in contractile and relaxation indices, without evidence of global ischemia. Epinephrine restored the mechanical performance to normal without significant change in coronary blood flow, myocardial oxygen consumption, or lactate and potassium balance.

Animals↗

Effects of atrial natriuretic peptide on systemic haemodynamics and cardiac function in normal man.

Atrial natriuretic peptides (ANP) reduce blood pressure. Animal experiments suggest that this depressor action results from a reduction in cardiac output rather than peripheral vascular resistance but it is unresolved whether this is wholly due to their effect of reducing left ventricular filling or whether they have a negatively inotropic effect. We have therefore investigated the effects of ANP in normal man using Doppler measurements of ascending aortic blood flow. Six normal volunteers underwent infusions of placebo and incremental doses of ANP in the range 0.25 to 12 micrograms.min-1. Each infusion was given for 15 min and measurements made both in the supine and erect positions (passive tilt). In both positions ANP had dose dependent effects of increasing heart rate (HR) and maximal acceleration whilst lowering an index of systemic vascular resistance (ISVR). In the erect position ANP also lowered systolic blood pressure. In the 30 min after completion of the infusions there were significant decreases in peak velocity and cardiac output with increases in ISVR in both positions, but HR fell and diastolic pressure increased only when supine. During the course of the experiment mean haematocrit (SEM) increased from 43.9 (1.2) to 46.7 (1.0), indicating a mean reduction in plasma volume of 10.5%. This occurred despite a negative fluid balance of only 31(7) ml over the 2 h. These data suggest that ANP is not negatively inotropic and that, at pharmacological doses, it is an arteriolar dilator of rapid offset and reduces cardiac filling pressures by a mechanism of slower offset.

Adult↗

Cardiovascular assessment for home healthcare nurses. Part II: Assessing blood pressure and cardiac function.

In Part I of this two-part series on cardiovascular assessment, the author described basic components of physical assessment relating to cardiac assessment such as skin color, integrity and hydration, pulses, shortness of breath, edema, and weight changes. In Part II, the intricacies of accurate blood pressure measurement, central venous pressure measurement, and heart and lung auscultation are described. Medication management and documentation within the context of home healthcare are also discussed.

Auscultation↗

Maternal cardiac function during pregnancy at high altitude.

OBJECTIVE: To investigate the maternal cardiovascular adaptation in pregnancy at high altitude, compared with that at sea level. DESIGN: Cross sectional study. SETTING: Two maternity units providing routine antenatal care: one at 4370 m above sea level (Cerro de Pasco, Peru) and one at sea level (Lima, Peru). POPULATION: We examined 175 pregnant women at 5-41 weeks of gestation and 16 non-pregnant controls resident at high altitude and 132 pregnant women and 18 non-pregnant controls at sea level. METHODS: Two-dimensional and M-mode echocardiography of the left ventricle. MAIN OUTCOME MEASURES: Maternal cardiac output and left ventricular longitudinal and transverse systolic function indices. RESULTS: Pregnancy at high altitude, compared with sea level, is associated with 11% lower birthweight and 31% lower maternal cardiac output, due to 15% lower stroke volume and 11% lower heart rate. The lower stroke volume was due to a lower preload and impaired longitudinal and transverse left ventricular systolic function. Mean arterial pressure was about 8% lower during pregnancy at high altitude versus sea level. Pregnant women at high altitude failed to expand their intravascular space to the same extent as the sea level group: cardiac output increased by 17%, left atrial diameter by 12% and end-diastolic diameter by 1% at high altitude versus 41%, 25% and 5%, respectively, at sea level. CONCLUSIONS: Pregnancy at high altitude, compared with sea level, is characterised by lower cardiac output due to lower heart rate and lower stroke volume and reduced expansion of the maternal intravascular space compared with the non-pregnant state.

Adaptation, Physiological↗

Maximal cardiac function in sedentary normal men and women: comparison of age-related changes.

The normal range of maximal values for oxygen consumption, heart rate, cardiac index, and stroke index during treadmill exercise testing are presented for 98 men and 104 women for ages 20-75 yr. These variables decrease with age in both sexes, but men show a significantly greater reduction than women with respect to oxygen consumption (P = 0.05), heart rate (P less than 0.02), and cardiac index (P less than 0.02). Comparison of the normal ranges of oxygen consumption, cardiac index, and stroke index indicated that men have significantly higher values than women (P less than 0.001). The normal range of heart rate was higher in younger men than women, but because of a more rapid decline with age in men, the older women had higher heart rates than the older men. Invasive measurements of cardiac index in 12 normal men and 11 normal women were within the defined normal range. These measurements showed that there was a greater increase in stroke index from supine rest to maximal upright exercise in men compared with the increase in women (means +/- SD, 12 +/- 9 m/m2 vs. 2 +/- 7 ml/m2, P less than 0.01).

Adult↗