Riccarda Del Bene

Low-Dose C-Type Natriuretic Peptide Does Not Affect Cardiac and Renal Function in Humans

In experimental animals, C-type natriuretic peptide (CNP) has vasodilating, hypotensive, and natriuretic activities. The role of circulating CNP in the overall regulation of cardiac and renal function in humans is less defined, in both health and disease. We measured cardiac volumes, diastolic and systolic functions, systemic (Doppler echocardiography) and renal hemodynamics, intrarenal sodium handling (lithium clearance method), plasma and urinary cGMP, plasma renin concentration, and plasma aldosterone level in six healthy volunteers (mean age, 33+/-3 years) receiving CNP (2 and 4 pmol/kg per minute for 1 hour each) in a single-blind, placebo-controlled, random-order, crossover study. During CNP infusion, plasma CNP increased from 1.17+/-0.23 to 41.52+/-4.61 pmol/L (ie, 4- to 10-fold higher levels than those observed in disease states) without affecting plasma and urinary cGMP, cardiac volumes, dynamics of left and right heart filling, cardiac output, arterial pressure, renal hemodynamics, intrarenal sodium handling, sodium excretion, or plasma levels of renin and aldosterone. The finding that increments in plasma CNP within the pathophysiological range have no effects on systemic hemodynamics, renal function, or the renin-angiotensin system do not support the hypothesis that CNP may act as a circulating hormone in humans.

Effects of exercise on natriuretic peptides and cardiac function in man

We evaluated cardiac function and the plasma levels of atrial (ANP) and brain (BNP) natriuretic peptides during bicycle (B) and hand-grip (HG) exercises in eight healthy males. Each test was preceded by a control protocol in resting conditions. Left ventricular (LV) function (echocardiography) was evaluated during both exercises. Atrial function was assessed only during HG. Plasma ANP significantly increased during B (+236%) and HG (+77%), while there was a significant trend towards higher plasma BNP levels during B (+41%) and HG (+30%) than during the corresponding control tests. Plasma ANP correlated with heart rate in both tests, with left atrial volume, pulmonary vein flow systolic fraction and mitral flow E/A ratio in HG; BNP in both test correlated with LV dimensions and function. These data suggest that during exercise the cardiac release of ANP and BNP is differently regulated and related to changes in left atrial and LV function, respectively.

Cardiovascular and renal function in normotensive and hypertensive patients with compensated cirrhosis: effects of posture

BACKGROUND/AIMS The aim of this study was to evaluate cardiovascular and renal function in patients with compensated cirrhosis and essential hypertension in the supine position and in response to standing up. METHODS Twenty-four patients with compensated cirrhosis (12 with elevated arterial pressure) and 20 healthy volunteers underwent echocardiographic evaluation of left ventricular end-diastolic and stroke volumes, ejection fraction, cardiac index, arterial pressure, peripheral resistance, creatinine clearance and sodium excretion in both the supine and the standing position. RESULTS When supine, only normotensive patients had a hyperdynamic circulation, with increased left ventricular end-diastolic and stroke volumes, cardiac index, and ejection fraction, and reduced peripheral resistance. Creatinine clearance and sodium excretion were comparable in patients and controls. Standing induced a decrease in end-diastolic volume in all subjects. Healthy volunteers maintained cardiovascular homeostasis by increasing ejection fraction and heart rate, while both normotensive and hypertensive cirrhotic patients experienced a fall in stroke volume and cardiac index, despite a marked activation of the renin-aldosterone and sympathetic nervous system. Creatinine clearance decreased only in normotensive patients, who experienced the greatest reduction in sodium excretion. CONCLUSIONS Compensated cirrhotic patients with arterial hypertension had no evidence of hyperdynamic circulation. Like their normotensive counterparts, hypertensive patients had an impaired cardiovascular response to the postural challenge, but a lesser degree of renal dysfunction during standing.

Abnormal coronary reserve and left ventricular wall motion during cold pressor test in patients with previous left ventricular ballooning syndrome

AIMS To investigate whether and how cold pressor test (CPT) could affect myocardial perfusion and left ventricular (LV) function in patients with previous LV ballooning syndrome (LVBS). METHODS AND RESULTS Cold pressor test (3 min hand immersion in ice-water) was performed in 17 women with previous LVBS and in 7 age- and risk factor-matched women with chest pain and normal coronary arteries. At baseline and peak CPT, global and regional LV function, and myocardial perfusion were quantitatively assessed by real-time three-dimensional echocardiography (RT3DE) and myocardial contrast (SonoVue, Bracco) 2D echocardiography (MCE), respectively (Philips iE33 machine, X3-1 and S5-1 probes). Data were analysed off-line (QLab 6.0 software). Peripheral venous catecholamines were assayed by high performance liquid chromatography with electrochemical detection. Cold pressor test induced similar haemodynamic changes and catecholamine increase in controls and LVBS patients. Left ventricular ejection fraction decreased and transient new mid-ventricular and apical motion abnormalities developed in LVBS patients only (quantitative RT3D analysis), without corresponding perfusion defects (MCE). At peak CPT, coronary blood flow and velocity increased (quantitative MCE analysis) in control subjects only. CONCLUSION Cold pressor test induced LV wall motion abnormalities unmatched to regional coronary flow reduction in LVBS patients only. The reduced coronary reserve in response to CPT suggests microvascular dysfunction in LVBS patients.

Cerebral autoregulation in patients with cirrhosis and ascites: A transcranial Doppler study

BACKGROUND/AIMS Patients with cirrhosis and ascites usually show alterations of systemic hemodynamics and are thus prone to develop arterial hypotension, which might result in cerebral hypoperfusion if cerebral autoregulation is impaired. METHODS We evaluated cerebral autoregulation in 15 patients with cirrhosis and ascites and 15 healthy subjects by monitoring mean blood flow velocity in the middle cerebral artery and arterial pressure during supine rest and passive tilting. RESULTS Tilt provoked a drop of arterial pressure in both groups. Control subjects had a prompt recovery of mean flow velocity and a progressive recovery of arterial pressure, so that, after 120 s, both parameters had returned to baseline: at 20 s the recovery of flow velocity was faster (p<0.01) than that of blood pressure. By contrast, patients with cirrhosis had a delayed and incomplete recovery of both parameters (p<0.01 vs healthy subjects). In eight patients, the recovery of mean flow velocity paralleled that of arterial pressure, indicating an impaired cerebral autoregulation. These patients had a worse liver function, a higher cardiac index and lower peripheral resistance. CONCLUSIONS Cerebral autoregulation is often impaired in patients with cirrhosis and ascites. These patients can develop cerebral hypoperfusion if arterial pressure falls abruptly.

Cardiovascular function in pregnancy: effects of posture

Objective To evaluate the cardiovascular response to active postural changes in pregnancy.

Cardiovascular Effects of Brain Natriuretic Peptide in Essential Hypertension

We evaluated the cardiovascular effects of pathophysiological plasma levels of brain natriuretic peptide in seven patients with mild to moderate essential hypertension by performing equilibrium radionuclide angiocardiography at baseline and during brain natriuretic peptide infusion at increasing doses (4, 8, 10, and 12 pmol/kg per minute for 20 minutes each). Brain natriuretic peptide induced a progressive reduction of left ventricular end-diastolic volume (from 107.5 +/- 10.3 to 89.0 +/- 11.0 mL at the end of all infusion periods) and end-systolic volume, whereas stroke volume did not show any significant change (from 64.9 +/- 5.9 to 62.7 +/- 7.8 mL). Cardiac output, arterial pressure, and peripheral vascular resistance did not change significantly. The lack of effects on systemic hemodynamics was probably due to compensatory activation of the sympathetic nervous system, as indicated by the significant increase in plasma norepinephrine levels (from 1.75 +/- 0.18 to 2.19 +/- 0.21 nmol/L), heart rate (from 68 +/- 6 to 81 +/- 6 beats per minute), peak ejection rate, and peak filling rate. These results indicate that brain natriuretic peptide, at the pathophysiological plasma concentrations reached in this study, influences cardiovascular homeostasis mainly by reducing cardiac preload.

The normal sequence of right and left atrial contraction

Objective: To study the sequence of atrial activation and the interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR).

Elevated plasma levels of urotensin II do not correlate with systemic haemodynamics in patients with cirrhosis

BACKGROUND The hyperdynamic circulation of hepatic cirrhosis is related to decreased systemic vascular resistance due to arterial vasodilation. Urotensin II plasma levels are increased in cirrhotic patients, and have been suggested to play a role in the pathogenesis of systemic haemodynamic alterations. AIM To evaluate the relationships between systemic haemodynamics and urotensin II plasma levels. METHODS Thirty-six consecutive in-patients with cirrhosis and no alteration of plasma creatinine, and 20 age- and gender-matched healthy volunteers underwent noninvasive assessment of systemic haemodynamics and measurement of urotensin II plasma levels. RESULTS In comparison to healthy controls, cirrhotic patients had signs of hyperdynamic circulation and higher plasma urotensin II levels. Plasma urotensin II was neither significantly different amongst patients with different severity of cirrhosis nor between patients with or without ascites. Both in controls and cirrhotic patients no significant correlations were found between parameters of systemic haemodynamics and plasma urotensin II levels. CONCLUSIONS In patients with cirrhosis and hyperdynamic circulation, but with normal serum creatinine, urotensin II is higher than in healthy subjects. However, no correlation with cardiac index or other haemodynamic parameters was observed, indicating that other mechanisms prevail.

T-Wave Alterations at the Onset of Wall Motion Abnormalities During Dobutamine Echocardiographic Stress Test

At the onset of wall motion alterations during dobutamine echocardiographic stress testing, a steeper increase in the overall T-wave amplitude in the precordial leads was observed in 17 patients with baseline normal wall motion, electrocardiogram, and critical coronary stenoses compared with 11 control subjects. Eleven patients with increasing T-wave amplitude had localized apical dyssynergy, whereas 6 patients with downward displacement of the ST segment had widespread wall motion alterations also located at the basal and midsegments.