Monica Failla

Effects of cigarette smoking on carotid and radial artery distensibility

Objective Cigarette smoking acutely induces a marked increase of blood pressure and heart rate. This is accompanied by a marked reduction of radial artery distensibility. Whether this reflects an alteration of arterial mechanics of large elastic arteries as well is not established, however. Design and methods In this study we addressed the acute effects of smoking on the stiffness of a peripheral medium-sized muscular artery and a large elastic vessel. We studied seven healthy normotensive smokers (age 28 ± 7 years, mean ± SEM), in the absence of smoking for at least 24 h. Radial artery (NIUS 02) and carotid artery diameter (WTS) were concomitantly acquired beat-to-beat in the 5 min before, during and after smoking of a cigarette containing 1.2 mg of nicotine. Blood pressure and heart rate were concomitantly recorded by a Finapres device. Radial and carotid artery distensibility were calculated according to the Langewouters and Reneman formulae, respectively. Data were collected for consecutive 30 s periods. Statistical comparisons were performed between the three different phases and, within each phase, between 30 s periods. In five subjects the protocol was repeated after 1 week using a stran rather than a cigarette to obtain data under sham smoking. Results Smoking increased systolic blood pressure by 14%, diastolic blood pressure by 10% and heart rate by 27%. Radial artery diameter was reduced during smoking (−3.7%) and more so after smoking (−14.8%), while carotid artery diameter did not change significantly either during or after smoking. Radial artery distensibility was also significantly reduced only after smoking (−41.3%, P < 0.01), while carotid artery distensibility was significantly reduced both during (−33.3%) and after smoking (−27.2%) (P < 0.01 versus before). No changes in blood pressure, heart rate and arterial wall mechanics were induced by sham smoking. Conclusions Acute cigarette smoking reduces distensibility not only in medium-sized but also in large elastic arteries, therefore causing a systemic artery stiffening. The mechanisms of these effects remain to be determined. However, it is likely that adrenergic mechanisms are responsible for the arterial distensibility alterations.

Early impairment of large artery structure and function in Type I diabetes mellitus

Aims/hypothesis. Diabetes mellitus is associated with an increased incidence of atherosclerosis. How early functional and structural alterations of large arteries that may preceed atherosclerosis occur in the course of this disease has, however, never been conclusively documented. Methods. We evaluated arterial wall distensibility in the radial artery, common carotid artery and abdominal aorta in 133 patients (aged 35.4 ± 0.9 years, means ± SEM) with Type I (insulin-dependent) diabetes mellitus and no macrovascular complications. Arterial distensibility was derived from continuous measurements of arterial diameter through echotracking techniques and use of either the Langewouters (radial artery) or the Reneman (carotid artery and aorta) formula. The same echotracking techniques enabled us to obtain radial artery and carotid artery wall thickness. Data were compared with those from 70 age-matched normotensive control subjects. Results. In diabetic patients arterial distensibility was consistently less (p < 0.01) than in control subjects, the reduction averaging 26 %, 14 % and 25 % for the radial artery, carotid artery and aorta, respectively. This was accompanied by an increase (p < 0.01) in both radial and carotid artery wall thickness. The changes were more pronounced in patients with microalbuminuria, retinopathy or neuropathy or both. They were evident also in those without microvascular complications. This was the case also when subjects in whom diabetes was associated with hypertension (n = 30) were excluded from data analysis. Carotid and aortic wall abnormalities showed a relation with the duration of disease and blood pressure whereas radial artery abnormalities showed a relation with glycated haemoglobin. Conclusion/interpretation. Type I diabetes is characterised by diffuse arterial wall stiffening and thickening which progress with the severity of the disease but can clearly be seen also in the absence of any diabetic-related complication. This suggests that in diabetes stiffening and thickening are an early marker of vascular damage. [Diabetologia (1999) 42: 987–994]

Sympathetic tone restrains arterial distensibility of healthy and atherosclerotic subjects

BACKGROUND Sympathetic activation induced by cold pressor test or cigarette smoking is accompanied by a marked reduction of radial artery distensibility. It is not known, however, whether arterial distensibility is under tonic sympathetic restraint, or whether this restraint involves arteries greater than the radial one in both normal and pathological conditions. METHODS We studied the distensibility of radial artery by continuous ultrasonographic assessment of the changes in arterial diameter over the diasto-systolic pressure range (finger pressure measurement) in eight patients with a Dupuytren disease before and 20 min after ipsilateral brachial plexus anaesthesia. We also studied ultrasonographic distensibility of femoral artery in seven subjects before and 20 min after ipsilateral subarachnoid anaesthesia, performed before arthroscopic surgery, and in five patients with claudicatio intermittens before and 1 month after ipsilateral removal of the lumbar sympathectomy chain. In all three conditions, the contralateral artery served as control. RESULTS The three interventions did not cause any significant alteration in blood pressure and heart rate. Radial artery distensibility was markedly increased by ipsilateral anaesthesia of the brachial plexus (+36%, P<0.01). This was the case also for femoral artery distensibility both following ipsilateral subarachnoid anaesthesia in healthy subjects (+47%, P<0.05) or ipsilateral sympathetic gangliectomy in patients with peripheral artery disease (+26%, P<0.05). In all three instances, the distensibility of the contralateral artery remained unaffected. CONCLUSIONS These data indicate that the sympathetic nervous system exerts a marked tonic restraint of arterial distensibility. This restraint involves medium-size and large muscular arteries and can also be seen in subjects with peripheral artery disease. This stiffening influence may increase the traumatic effect of intravascular pressure on the vessel wall and favour atherosclerosis.

Impaired radial artery compliance in normotensive subjects with familial hypercholesterolemia

Hypercholesterolemia impairs arteriolar dilatation, but whether the vascular abnormalities accompanying this condition include large artery function is unknown. We addressed this issue in 13 normotensive subjects with familial hypercholesterolemia (serum cholesterol 401.6 +/- 16.9 mg/dl, mean +/- S.E., FHC) and no evidence of atherosclerotic lesions, in whom radial artery (RA) diameter and blood pressure (BP) were measured beat to beat by an echotracking and a Finapres device, respectively. RA compliance (RAC) was derived from the diameter/BP relationship and expressed over the systo-diastolic BP range, both at baseline and after a 12-min brachial artery occlusion. RAC was expressed also as the area under the RAC/BP curve divided for pulse BP. Measurements included maximal forearm blood flow (plethysmography) and minimal forearm vascular resistance (FVR) which were obtained from the values following the 12-min brachial arterial occlusion. Data were collected before and after 6- and 24-month lipid lowering treatment (simvastatin 40 mg/day). Ten age-matched normotensive normocholesterolemic healthy subjects (N) served as controls. Compared to N, baseline RAC was strikingly reduced in FHC (-53.5%, P < 0.01). After ischemia RAC increased significantly and markedly in N (+38.7, P < 0.01), while only a modest and non-significant increase was observed in FHC. Minimal FVR was markedly higher in FHC than in N (3.5 +/- 0.9 vs 1.6 +/- 0.1 units, P < 0.01). In FHC (7 subjects) RAC remained unchanged after 6 months of lipid lowering treatment, but increased markedly (+55.2%, p < 0.05) when treatment was prolonged to 24 months. Lipid lowering treatment also reduced minimal FVR, the effect being significant both after 6 and after 24 months. No changes in RAC and minimal FVR were seen after 6 months in controls. Thus, in subjects with a marked increase in serum cholesterol due to FHC, not only arteriolar dilatation, but also RAC and distensibility are markedly impaired. This impairment can be favourably affected by an effective lipid lowering treatment of long duration.

Sympathetic Modulation of Radial Artery Compliance in Congestive Heart Failure

Animal studies have suggested that arterial compliance can be modulated by adrenergic influences. Whether this adrenergic modulation also occurs in humans is still a matter of debate. In the present article we address this issue by examining the relationships between sympathetic tone and arterial compliance in a variety of physiological and pathophysiological conditions. We have found that cigarette smoking, ie, an action that produces a marked sympathetic activation, causes a significant reduction in radial artery compliance, as measured by an echotracking device capable of providing continuous beat-to-beat evaluation of this hemodynamic variable. When expressed as compliance index, ie, as the ratio between the area under the compliance-pressure curve and pulse pressure, the reduction amounted to 35.7 +/- 4.8% (mean +/- SEM) and was independent of the smoking-related blood pressure increase. Furthermore, pharmacological stimulation of adrenergic receptors located in the arterial wall was also shown to affect arterial compliance because the radial artery compliance index was markedly reduced (- 29.5 +/- 3.9%) during phenylephrine infusion in the brachial artery at doses devoid of any systemic blood pressure effect. Evidence was also obtained that the relationship between sympathetic activation and arterial compliance has pathophysiological relevance, because in 17 patients with congestive heart failure (New York Heart Association classes II through IV) there was a significant inverse correlation (r = .62, P < .01) between muscle sympathetic nerve activity (directly measured by microneurography in the peroneal nerve) and radial artery compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Radial, Carotid and Aortic Distensibility in Congestive Heart Failure: Effects of High-Dose Angiotensin-Converting Enzyme Inhibitor or Low-Dose Association With Angiotensin Type 1 Receptor Blockade

UNLABELLED objectives; The aim of this study was to determine whether in patients with congestive heart failure (CHF) a distensibility (Dist) reduction: 1) similarly occurs in different arteries; 2) is related to CHF severity; and 3) is reversible with treatment. background: Several studies suggest that CHF is accompanied by a reduced arterial Dist. METHODS We measured diameter in radial artery, carotid artery (CA) and abdominal aorta (AO) by echotracking. Distensibility was obtained by relating it to blood pressure. Data were collected in 30 patients with CHF (New York Heart Association functional class I to III) under standard treatment with diuretic, digitalis and angiotensin-converting enzyme (ACE) inhibitor in whom CHF severity was assessed by maximum oxygen consumption (VO(2)max) percentage and in 30 age- and gender-matched controls. Patients with CHF were then randomized to maintain standard treatment (n = 10), double the ACE inhibitor dose (n = 10) or add an angiotensin II antagonist (n = 10) and restudied after two months. RESULTS Distensibility was markedly reduced in the CHF group in all three vessels (p < 0.01), CA and AO Dist being related to CHF severity (p < 0.05). After two months, Dist did not change in the group maintained under standard treatment, but it increased significantly (p < 0.05) and similarly when the ACE inhibitor dose was doubled or an angiotensin II antagonist was added. CONCLUSIONS Congestive heart failure is characterized by a reduction of Dist of large-elastic and middle-sized muscular arteries. The reduction of large-elastic artery Dist is related to the CHF severity. These alterations can be reversed by drugs, effectively interfering with the renin-angiotensin system either at the ACE or at the angiotensin receptor level.

Progression of large artery structural and functional alterations in Type I diabetes

Aims/hypothesis. Type I (insulin-dependent) diabetes mellitus is accompanied by reduced arterial distensibility and increased arterial wall thickness even in normotensive subjects with no micro-macrovascular complications. It is not known whether, and how fast, these subclinical markers of vascular damage develop over time. Methods. We measured arterial wall distensibility in radial, common carotid artery and abdominal aorta in 60 normotensive patients (aged 35.0 ± 1.2 years, means ± SE) with Type I diabetes with no microvascular or macrovascular complications and in 20 healthy control subjects matched for age. Arterial distensibility was determined by continuous measurements of arterial diameter through echotracking techniques and by using either the Langewouters (radial artery) or the Reneman formula (carotid artery and aorta). The same echotracking techniques allowed us to ascertain the radial and carotid artery wall thickness. Data were collected before and after 23 ± 1 months. Results. In the first study, carotid artery distensibility was similar but radial artey and aortic distensibility was less (p < 0.01) in patients with diabetes than in control subjects (–39 % and 25 % respectively). This was accompanied by an increase (p < 0.01) in both radial (42 %) and carotid artery wall thickness (46 %). After 23 ± 1 months diabetic subjects showed a further reduction in arterial distensibility (radial–12 %, p < 0.05; carotid–8 %, NS; aorta–20 % p < 0.05) and an increase in arterial wall thickness (radial + 15 %; carotid 14 %, p < 0,05). No change in distensibility and wall thickness values occurred in control subjects. Conclusion/interpretation. The early reduction in arterial distensibility and increase in arterial wall thickness characterizing uncomplicated normotensive Type I diabetes patients shows a measurable worsening over the short term. [Diabetologia (2001) 44: 203–208]

Fluctuations of Radial Artery Distensibility Throughout the Menstrual Cycle

Estrogen administration has a number of favorable cardiovascular effects, and recent evidence suggests that these include an increase in arterial distensibility. Whether this is also the case for the physiological changes in estrogen production during the menstrual cycle has never been determined, however. In 21 premenopausal healthy women, we continuously measured radial artery diameter and blood pressure by an echo-tracking device and a beat-to-beat finger device, respectively. Arterial distensibility was calculated as distensibility/blood pressure curve. The measurements were made during the follicular, ovulatory, and luteal phases of the menstrual cycle. As expected, compared with the follicular phase, plasma estradiol, follicle-stimulating hormone, luteinizing hormone, and prolactin were increased in the ovulatory phase, whereas progesterone was increased in the luteal phase, together with antidiuretic hormone. Radial artery distensibility was increased in the ovulatory and reduced in the luteal phase, the changes being independent of the small, concomitant blood pressure changes. The arterial wall stiffening seen in the luteal phase was associated with a reduction in the flow-dependent endothelial dilatation of the radial artery as assessed by the hyperemia after short-term ischemia of the hand. Thus, the natural menstrual cycle is characterized by alterations in radial artery distensibility. The mechanisms responsible for this phenomenon remain to be clarified. It is possible, however, that the greater arterial distensibility of the ovulatory phase is due to an estrogen-dependent reduction in vascular smooth muscle tone, whereas the arterial stiffening of the luteal phase depends on vascular smooth muscle contraction due to more complex hormonal phenomena, ie, an endothelial impairment due to estrogen reduction but also to an increase in progesterone and antidiuretic hormone levels.

Liver damage in Italian patients with hereditary hemochromatosis is highly influenced by hepatitis B and C virus infection.

We evaluated the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in 78 Italian patients with hereditary hemochromatosis as well as the relation between HCV antibody (anti-HCV) status, hepatitis B surface antigen (HBsAg) and liver histology. None of the patients had been transfused or ever consumed more than 60 g of alcohol per day. Eighteen showed histological signs of chronic hepatitis, active cirrhosis was present in 12, chronic active hepatitis in 4 and chronic persistent hepatitis in 2. Liver fibrosis or cirrhosis without inflammatory activity was observed in 31 subjects, whereas liver histology was normal except for iron overload in 18. The prevalence of HBsAg in the whole series was 5% and of anti-HCV was 20.5%. The prevalence of HBsAg and anti-HCV was significantly higher in the chronic hepatitis group than in the fibrosis/cirrhosis (p = 0.01) and the normal groups (p < 0.01). Fourteen of 18 hereditary hemochromatosis patients with chronic hepatitis were HBsAg (4) or anti-HCV (10) positive and all the latter subgroup had HCV-RNA in their serum as shown by the polymerase chain reaction. Although most of the patients with associated chronic hepatitis had cirrhosis, their serum ferritin levels and amount of mobilizable iron were significantly lower than those of the fibrosis/cirrhosis group (p < 0.01). This indicates that hepatitis viral infection acts synergistically with iron in accelerating the development of liver damage.

Effects of Heart Rate Changes on Arterial Distensibility in Humans

Abstract—In rats, an increase in heart rate by pacing is accompanied by progressive large-artery stiffening. Whether this is also the case in humans is unknown. We enrolled 20 patients who were chronically implanted with a pacemaker because of atrioventricular block or sick sinus syndrome. Arterial distensibility was measured by an echo-tracking device. In 10 patients, the evaluation was performed on the radial artery by using continuous finger blood pressure measurements, whereas in the remaining 10 patients, the common carotid artery was studied with a semiautomatic measure of brachial artery blood pressure. Diastolic diameter, systodiastolic diameter change, and distensibility were obtained at baseline (heart rate 63±2 beats/min) and after atrial and ventricular sequential pacing at a heart rate of 90 and 110 beats/min. At baseline, the diameter was 7.8±0.3 mm in the carotid artery and 2.4±0.1 mm in the radial artery; the respective systodiastolic diameter change values were 375.4±31.0 and 55.9±9.0 (&mgr;m) and the distensibility values were 1.4±0.1 and 0.7±0.1 (1/mm Hg 10−3). Blood pressure and diameter were not significantly modified by increasing heart rate, which markedly modified systodiastolic diameter change and distensibility. In the radial artery, distensibility was reduced by 47% (P <0.05) at a heart rate of 90 beats/min with no further reduction at 110 beats/min. In the carotid artery, distensibility was reduced by 20% at a heart rate of 90 beats/min (P <0.05) with a further reduction at 110 beats/min (45%, P <0.05). These data provide the first evidence in humans that acute increases in heart rate markedly affect arterial distensibility and that this occurs in both large- and middle-size muscle arteries within the range of “normal” heart rate values.