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A Morganti

Publications and source records attributed to A Morganti.

At least 19 recordsLinked to original sources
PubMed2006

New intrarenal echo-Doppler velocimetric indices for the diagnosis of renal artery stenosis.

We aimed at comparing the positive and negative predictive values (PPV, NPV) of several intrarenal velocimetric indices for revealing the presence of renal artery stenosis (RAS) among hypertensive patients who underwent a renal angiography for the clinical suspicion of renovascular hypertension. In 106 patients (200 kidneys), the pulsatility index (PI) and resistive index (RI), the acceleration time (AT), and the mean systolic acceleration (ACC(sys)) were evaluated. In addition, the maximal systolic acceleration (ACC(max)), that is, the maximal slope of the acceleration phase, and the maximal acceleration index (AI(max)), that is, the ratio between ACC(max) and the relative peak systolic velocity, were calculated. On angiography, we found that 56 (28%) of the 200 arteries had a greater than 60% RAS. PI and RI had an NPV below 75%, whereas AT, ACC(sys), ACC(max), and AI(max) had an NPV always above 95%. However, ACC(max), and AI(max), at their best cutoff limits, had higher PPV than ACC(sys) and AT (60 and 70% vs 45 and 51%, respectively). Thus, in a cohort of patients with a high prevalence of RAS, PI and RI failed to reach an NPV adequate for a screening test. In contrast, all the acceleration indices we tested had a sufficiently high NPV but AI(max) appears superior to the others because of higher PPV. We propose the evaluation of AI(max) as an additional screening test in patients with hypertension and the clinical suspicion of RAS.

Adult↗
PubMed2001

Non-motor effects of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: preliminary physiological results.

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain largely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiology. Nine patients affected by PD undergoing chronic DBS of the STN have been studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent period and sympathetic skin response (SSR) studies with DBS ON and OFF. To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N20 and the VEP P100 component increased significantly in amplitude whereas the SSR decreased in amplitude and increased in latency. Although plasma renin activity tended to increase with DBS OFF, its modification induced by postural changes and blood pressure values did not significantly differ with DBS ON and OFF. We conclude that DBS of the STN in PD, besides inducing a clinical improvement, induces several non-motor effects.

Afferent Pathways↗
PubMed2001

Usefulness and limits of distal echo-Doppler velocimetric indices for assessing renal hemodynamics in stenotic and non-stenotic kidneys.

BACKGROUND: Distal echo-Doppler velocimetric indices are widely used for revealing the presence of a renal artery stenosis but there is scarce information as to whether they reflect the renal hemodynamics in stenotic and nonstenotic kidneys. OBJECTIVES AND METHODS: We evaluated the pulsatility and resistive indices (PI and RI), acceleration (A) and acceleration time (At) and correlated their values with those of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), renal vascular resistance (RVR) and filtration fraction (FF) estimated by single kidney scintigraphy in 24 kidneys with 70-95% renal artery stenosis (atherosclerotic n = 17, fibromuscular n = 7) and in 27 non-stenotic kidneys (11 contralateral to renal artery stenosis and 16 of patients with essential hypertension). In patients with stenotic kidneys, these measurements were repeated within 7 days after a successful percutaneous transluminal renal angioplasty (PTRA) (in 11 arteries performed in combination with stent implantation). RESULTS: Prior to dilation we found that the stenotic kidneys had significantly lower values of ERPF, GFR and higher RVR than the non-stenotic kidneys and that these hemodynamic alterations were associated with those, also statistically significant, of the four velocimetric indices. In non-stenotic kidneys, there were highly significant relationships between PI and ERPF, and RVR (r = -0.68 and 0.81 respectively P < 0.01); similar relationships were found for RI (r = -0.67 and 0.78 P < 0.01) whereas no such correlations were found between these two velocimetric indices and GFR and FF; also no correlations were found between A and Atand ERPF, GFR, RVR and FF. In stenotic kidneys no significant correlations were found between any of the velocimetric and the hemodynamic indices. Renal artery dilation induced clear cut increments in ERPF, GFR and reduction in RVR in post-stenotic kidneys, which were associated with normalization of all four velocimetric indices. No relationships were observed between the renal hemodynamic and the velocimetric changes induced by dilation; however in post-stenotic kidneys the relationships between PI and RI, ERPF and RVR were restored as in nonstenotic kidneys. CONCLUSIONS: These data indicate that PI and RI can be used to assess ERPF and RVR both in non-stenotic and post-stenotic kidneys; however, none of the velocimetric indices examined in this study can provide valid informations on the renal hemodynamics of stenotic kidneys and on their changes induced by PTRA.

Adolescent↗
PubMed2001

Blunted vascular and renal effects of exogenous atrial natriuretic peptide in patients with cushing's disease.

The role of atrial natriuretic peptide (ANP) in glucocorticoid hypertension is still controversial, as glucocorticoids enhance the secretion of ANP in vivo, but reduce its biological activity in vitro. In isolated cells, for example, the cGMP response to ANP is suppressed by dexamethasone. We tested the in vivo relevance of this observation by comparing the cGMP, endocrine, and renal responses to exogenous ANP in patients with Cushing's disease (CD; n = 10) and in a matched group of essential hypertensives (EH; n = 8) and normotensive controls (N; n = 4). alpha-human-ANP was infused at 0.01 microg/kg/min for 120 min with a 30-min recovery period; hormonal and arterial pressure measurements were performed at 30-min intervals, and renal parameters were measured at baseline and after infusion. There was a 4-fold increase in plasma ANP in all groups, but the increments in plasma cGMP were about 50% lower in CD than in N and EH; urinary cGMP was similarly lower in CD (247 +/- 61 vs. 529 +/- 146 and 384 +/- 54 nmol/150 min, respectively). This was associated with a reduced peak increase in hematocrit in CD (+2.6 +/- 0.9%) compared with N (+6.6 +/- 0.9%) and EH (+7.1 +/- 0.7%; P < 0.05 CD vs. both); the diuretic and natriuretic effects of ANP were also lower in CD than in EH with very similar systemic pressure levels (382 +/- 63 vs. 848 +/- 130 mL/150 min, and 61 +/- 14 vs. 113 +/- 14 mmol/150 min, respectively; P < 0.05 for both). The increments in plasma and urinary cGMP in response to physiological doses of ANP are thus blunted in CD patients compared with those in N and EH. This biochemical defect is associated with reduced capillary permeability and a lesser diuretic and natriuretic effect. These data are compatible with an impairment of the biological activity of ANP in glucocorticoid hypertension in humans.

Adult↗
PubMed2000

Modulation of sympathetic coronary vasoconstriction by cardiac renin-angiotensin system in human coronary heart disease.

BACKGROUND: In humans, angiotensin II enhances the sympathetic coronary vasoconstriction elicited by the cold pressor test (CPT) and diving. Whether this enhancement depends on the circulating angiotensin II or on the locally produced angiotensin II is unknown, however. METHODS AND RESULTS: We addressed this issue in 14 patients with severe coronary artery disease by evaluating the effects of a 2-minute CPT (n=14) and a 30-second dive (n=8) on mean arterial pressure (MAP, arterial catheter), heart rate (ECG), coronary sinus blood flow (CBF, thermodilution technique), and coronary vascular resistance (MAP/CBF ratio). The 2 stimuli were applied at the end of left intracoronary infusion of either saline or benazeprilat diluted at the concentration of 25 microgram/mL. The rate of benazeprilat infusion had been preliminarily demonstrated to reduce angiotensin II concentration in the coronary sinus without affecting its arterial concentration. The changes in MAP and heart rate induced by CPT and diving were superimposable during saline and benazeprilat infusions. The decrease in CBF induced by CPT and diving during saline infusion was changed into an increase during benazeprilat infusion with a significant attenuation of the coronary vasoconstrictor response. CONCLUSIONS: In patients with coronary artery disease, an attenuation of sympathetic coronary vasoconstriction can be obtained by reducing cardiac angiotensin II formation without involving circulating angiotensin II. This suggests a role of the tissue renin-angiotensin system in modulating autonomic cardiac drive in humans.

Aged↗
PubMed2000

Angioplasty of atherosclerotic and fibromuscular renal artery stenosis: time course and predicting factors of the effects on renal function.

The effects of percutaneous transluminal renal angioplasty (PTRA) on the renal function of stenotic kidneys are usually assessed by evaluating the changes in serum creatinine, which is quite a rough indicator of glomerular filtration rate (GFR). In 27 hypertensive patients with 19 atherosclerotic and 11 fibromuscular significant renal artery stenoses, we investigated with renal scintigraphy the short-term (5 days) and long-term (10 months) effects of a technically successful PTRA (in seven cases combined with a stent implantation) on GFR of the stenotic and contralateral kidneys; these measurements were combined with those of plasma renin activity (PRA) and of angiotensin II (AII). We found that in short-term studies after PTRA GFR rose from 29.7 +/- 3.5 to 34.6 +/- 3.1 mL/min and from 36.9 +/- 4.0 to 45.1 +/- 4.3 mL/min, respectively, in atherosclerotic and fibromuscular poststenotic kidneys. In long-term studies GFR further and significantly increased, to 37.8 +/- 3.2 mL/min in the former group, whereas it stabilized in the latter group (46.0 +/- 3.6 mL/min). In patients with fibromuscular stenosis these changes in GFR were associated with clear-cut reductions in blood pressure (BP), PRA, and AII; these decrements also occurred in patients with atherosclerotic stenosis but to a much lesser extent. We also found that in short- and long-term studies the percent of PTRA-induced increments of GFR in the poststenotic kidneys were inversely correlated with the baseline values of GFR. In addition, the absolute and percent increments of GFR were positively correlated with the basal levels of AII. Thus the time course of the improvement in GFR after angioplasty may differ in kidneys, depending on the etiology of the stenosis, in that in those with fibromuscular stenosis it was entirely apparent within a few days whereas in those with atherosclerotic stenosis it required several months to be fully expressed. Also, it appears that the more compromised kidneys are those that benefit most from the dilatation and that AII levels are useful indicators of the possibility that the stenotic kidney will have a favorable functional outcome in terms of restoration of renal blood flow.

Adolescent↗
PubMed2000

Plasma endothelin levels: a meaningless number?

Endothelin (ET)-1 is a potent vasoactive peptide which is mostly secreted toward the vessel wall and the circulatory levels of which are quite low; for these reasons changes in plasma ET-1 may be difficult to detect even after the application of strong stimuli, which, in theory, should profoundly alter its production. We have examined the effects of a number of such stimuli and found that in humans the only one which consistently increased plasma ET-1 was the exposure to hypobaric hypoxia; moreover under these circumstances the increments in plasma ET-1 were correlated with the changes in pulmonary systolic pressure, suggesting a role of circulating ET-1 in the adaptation of pulmonary vessels to high altitude. In contrast no consistent changes of ET-1 were observed in response to sympathetic activation induced either by exposure to cold, standing, reduction in blood pressure and blood withdrawal. In response to angioplasty of renal artery stenosis a concomitant reduction in plasma ET-1 and angiotensin II (AngII) was observed in patients who, prior to angioplasty, had a high degree of activation of the renin system, supporting the possibility that in these specific conditions AngII may actually stimulate ET-1 production in vivo.

Adaptation, Physiological↗
PubMed2000

[Hypertension and the progression of organ damage].

The heart is one of the most important targets of arterial hypertension to which this organ responds with the development of left ventricular hypertrophy. This structural alteration, which is rather frequent already in the early stages of hypertension, derives from a complex interaction of hemodynamic and humoral factors and represents a compensatory mechanism for maintaining a normal cardiac output in spite of the elevated peripheral resistance; yet, with time, left ventricular hypertrophy exposes patients to an additive risk of ischemia, dysrhythmias and cardiac failure. However the progression towards these clinical manifestations of cardiac deterioration is susceptible nowadays to be halted thanks to the efficacy of antihypertensive drugs and particularly of those antagonizing the activity of the renin-angiotensin system.

Disease Progression↗
PubMed1999

Renal angioplasty: better for treating hypertension or for rescuing renal function?

Angioplasty of renal artery stenosis has been used extensively in the last two decades for treating renovascular hypertension, and, more recently, for preserving the jeopardized renal function. A large body of evidence has accumulated indicating that this approach is by far the most convenient for patients with fibromuscular stenosis in whom the technical success of the procedure is followed by a high cure rate (50%) or at least by some improvement of blood pressure (40%). In contrast, in patients with atheromatous stenosis, the rate of cure is very low (8-10% at best) and the rate of improvement is between 40 and 50% irrespective of whether the stenosis is treated with angioplasty or with stent implantation. Thus, before undergoing procedures which are not devoid of potentially serious side-effects, these patients should be thoroughly investigated to select those in whom the benefit actually outweighs the risks. Studies investigating the effects of angioplasty on renal function are less numerous than those addressing the effects on blood pressure, and, in most cases, suffer the limitation of using the levels of serum creatinine as the sole marker of the changes in glomerular filtration rate induced by the procedure. These investigations have shown that some amelioration can be achieved in one-third of patients, with another third having unmodified levels of creatinine at follow-up. Radioisotopic techniques, which allow a more precise and separate evaluation of the function of the two kidneys, appear to be a promising alternative for the investigation of the effects of angioplasty; indeed, preliminary studies which took advantage of these methodologies have shown that the function of the stenotic kidney can possibly be rescued by slowly reversing the multiple mechanisms by which chronic ischaemia damages the kidney.

Angioplasty↗
PubMed1999

Renovascular hypertension. Clinical and diagnostic clues.

Renovascular hypertension (RVH), although relatively rare, is the most frequent among the secondary forms of arterial hypertension; in addition interventional radiology has remarkably increased, because of its relative invasiveness, the possibilities of treating and in many cases curing RVH bypassing the traditional surgical approach. For these reasons in recent years a number of screening tests has been developed and added to renal angiography and to the measurement of plasma renin which, still now, represent the reference methods among the morphological and the functional tests respectively. These new and promising techniques include the magnetic resonance angiography, the spiral computed tomography, the renal scintigraphy and the ultrasound scanning of renal arteries with the associated measurement of velocimetric indices. In selected populations all these methods have been shown to possess an high specificity and sensitivity but if applied to a general population of hypertensive patients their positive predictive values are going to be necessarily low because of the low prevalence of the disease. Accordingly, it is mandatory for the physician, before sending patients to these investigations, to preselect those who, on the basis of a thorough clinical examination are more likely to harbour a renal artery stenosis.

Diagnosis, Differential↗
PubMed1999

Interventional radiology in the treatment of renal artery stenosis.

Percutaneous transluminal renal angioplasty (PTRA) alone or in combination with stent implantation, is increasingly used as an alternative technique to surgical revascularization for treatment of renal artery stenosis (RAS) wich may cause hypertension or jeopardize renal function. Herein we report the results obtained with 305 PTRAs performed in 242 hypertensive patients, 144 of whom had atherosclerotic RAS, 69 fibromuscolar dysplasia, 15 Ras in transplanted kidneys, 6 restenosis in surgically revascularized kidneys, 4 Takayasu arteritis and 4 neurofibromatosis. Stents were implanted in 68 cases, mostly in atherosclerotic stenoses. The technical success was achieved in 261 arteries (85.6%), with 33 failures (10.8%) and 11 (3.6%) procedures not completed for anatomical reasons. PTRA related complications were observed in 23 cases (7.5%), but no fatalities occurred. An overall benefit on blood pressure control was observed in 41% of patients with atherosclerotic RAS and in 68% of those with fibromuscolar dysplasia. It appears that independently from the ethiology PTRA is technically effective in correcting RAS; yet the position of PTRA with respect to that of medical or surgical treatment needs to be better delineated through randomized, controlled studies aimed at comparing the clinical efficacies of these different approaches.

Adult↗
PubMed1998

Effects of balloon angioplasty and stent implantation on intrarenal echo-Doppler velocimetric indices.

This study was aimed at examining whether four intrarenal echo-Doppler velocimetric indices (pulsatility and resistive indices, acceleration and acceleration time) can be useful for assessing the effects of renal artery dilation obtained with either angioplasty or stent implantation. Echo-Doppler studies were performed in 63 hypertensive patients with 68 renal artery stenoses (39 atherosclerotic and 29 fibromuscular) prior to and within five days after the dilation procedures (55 angioplasties, 13 stent implantations), which resulted in an average reduction of arterial narrowing from 79% to 20%. In 24 patients, the velocimetric indices were also examined in relationship to the venoarterial differences of plasma renin activity and of angiotensin II across the stenotic kidneys. We found that after dilation the values of the four indices had returned within the normal range in all but three arteries (one false negative for resistive index and two for acceleration time). However, decrements in acceleration time was the only factor to be significantly correlated with the reduction of arterial narrowing. Moreover, postdilation values of this index were, on average, slightly but significantly higher in arteries that at follow-up developed restenosis rather than in those that remained patent. For similar reductions in arterial narrowing the absolute changes of all indices were similar in atherosclerotic and fibromuscular stenotic arteries and, in a subset of the atheromatous arteries, were also similar after angioplasty and stent implantation. No relationship was found with the changes in the venoarterial differences of plasma renin activity and angiotensin II. It appears that these intrarenal velocimetric indices and, in particular, acceleration time reliably reflect the technical success of renal artery dilation. The acceleration time index may also be valuable for predicting the restenosis of the dilated vessel. None of the indices, however, mirrors the functional consequences of removal of renal artery stenosis as expressed through the changes in transrenal gradients of the components of the renin-angiotensin system.

Adolescent↗
PubMed1998

Hemodilution reduces clinic and ambulatory blood pressure in polycythemic patients.

Limited information is available for humans on whether blood viscosity affects total peripheral resistance and, hence, blood pressure. Our study was aimed at assessing the effects of acute changes in blood viscosity on both clinic and 24-hour ambulatory blood pressure (BP) values. In 22 normotensive and hypertensive patients with polycythemia, clinic and 24-hour ambulatory BPs were measured before and 7 to 10 days after isovolumic hemodilution; this was performed through the withdrawal of 400 to 700 mL of blood, with concomitant infusion of an equivalent volume of saline-albumin solution. Hematocrit, plasma renin activity, plasma endothelin-1, right atrial diameter (echocardiography), and blood viscosity were measured under both conditions. Plasma renin activity and right atrial diameter were used as indirect markers of blood volume changes. Plasma endothelin-1 was used to obtain information on a vasomotor substance possibly stimulated by our intervention, which could counteract vasomotor effects. Isovolumic hemodilution reduced hematocrit from 0.53+/-0.05 to 0.49+/-0.05 (P<.01). Plasma renin activity, plasma endothelin-1 and right atrial diameter were unchanged. Clinic blood pressure was reduced by hemodilution (systolic, 144.3+/-5.4 to 136.0+/-3.9 mm Hg[mean+/-SEM]; diastolic, 87.0+/-2.8 to 82.1+/-2.6 mm Hg, P<.05 for both) and a reduction was observed also for 24-hour average ABP (systolic, 133.6+/-2.9 to 129.5+/-2.7 mm Hg; diastolic, 80.0+/-2.0 to 77.3+/-1.7 mm Hg, P<.05 for both). The reduction was consistent in hypertensive patients (n = 12), whereas in normotensive patients (n = 10) it was small and not significant. Both clinic and 24-hour average heart rates were unaffected by the hemodilution. Thus, in polycythemia, reduction in blood viscosity without changing blood volume causes a significant fall in both clinic and 24-hour ambulatory BPs; this is particularly true when, as can often happen, blood pressure is elevated. This emphasizes the importance this variable may have in the determination of blood pressure and the potential therapeutic value of its correction when altered.

Blood Pressure↗
PubMed1997

Effects of chronic ACE inhibition on sympathetic nerve traffic and baroreflex control of circulation in heart failure.

BACKGROUND: In congestive heart failure ACE inhibitors chronically reduce plasma norepinephrine. No information exists, however, on whether and to what extent this reduction reflects a true chronic inhibition of sympathetic outflow and which mechanisms may be responsible. METHODS AND RESULTS: In 24 patients aged 60.3+/-2.0 years (mean+/-SEM) affected by congestive heart failure (New York Heart Association class II) and treated with diuretics and digitalis, we measured mean arterial pressure (Finapres), plasma renin activity and angiotensin II levels (radioimmunoassay), plasma norepinephrine (high-performance liquid chromatography), and muscle sympathetic nerve activity (microneurography at a peroneal nerve) at rest and during baroreceptor stimulation and deactivation caused by stepwise intravenous infusions of phenylephrine and nitroprusside, respectively. In 12 patients measurements were repeated after a 2-month addition of the ACE inhibitor benazepril (10 mg/d P.O.), while in the remaining 12 patients they were performed again after 2 months without any treatment modifications. Benazepril did not alter mean arterial pressure, markedly increased plasma renin activity, reduced plasma angiotensin II, and caused a nonsignificant reduction in plasma norepinephrine. In contrast, muscle sympathetic nerve traffic was significantly reduced (-30.5+/-5.3%, P<.01). This reduction was accompanied by no change in the sympathoexcitatory responses to baroreceptor deactivation but by a marked enhancement of the sympathoinhibitory responses to baroreceptor stimulation (103.5+/-3.4%). CONCLUSIONS: These results provide the first direct evidence that in congestive heart failure chronic ACE inhibitor treatment is accompanied by a marked reduction in central sympathetic outflow. This reduction may depend on a persistent restoration of baroreflex restraint on the sympathetic neural drive.

Angiotensin II↗
PubMed1997

Mechanism and pressor relevance of the short-term cardiovascular and renin excitatory actions of the selective A2A-adenosine receptor agonists.

Selective A2A adenosine receptor agonists are potent vasodilators that reduce blood pressure and induce marked increments in heart rate and plasma renin activity (PRA). To examine the mechanisms and pressor relevance of these cardiac and renin responses, we measured blood pressure and heart rate by telemetry and PRA in separate sets of spontaneously hypertensive rats (SHRs), which were given i.p. 2-hexynyl-5-methylcarboxamidoadenosine (2HE-NECA, 0.01 mg/kg) and 2-[4-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadenosin e (CGS 21680, 0.1 mg/kg) alone and after pretreatment with the beta 1-adrenoceptor blocking agent atenolol (100 mg/kg). The effects of 2HE-NECA (0.003 mg/kg) also were examined after pretreatment with the angiotensin-converting enzyme (ACE) inhibitor spirapril (3 mg/kg). Both A2A agonists induced marked reductions in blood pressure, associated with significant increments in heart rate and in PRA. Atenolol reduced blood pressure to the same extent as did the A2A agonists and markedly decreased heart rate and PRA. Pretreatment with atenolol entirely prevented the increase in heart rate and in PRA induced by the two A2A agonists but potentiated only slightly their antihypertensive effect. Spirapril alone reduced blood pressure and increased PRA and when given before 2HE-NECA potentiated its depressor and renin-stimulating effects by 44% and 69%, respectively. These results suggest that the increase in heart rate and in PRA induced by A2A agonists is the result of a reflex increase in sympathetic activity triggered by the decrease in blood pressure rather than of a direct stimulating effect on cardiac and renal A2A-adenosine receptors; the reactive activation of the renin-angiotensin system elicited by these compounds may contribute to blunting their antihypertensive effect.

Adenosine↗