Randomized clinical trial of angiotensin-converting enzyme inhibitor, ramipril, in patients with intermittent claudication.

BACKGROUND: The aim was to investigate the effect of ramipril on clinical parameters in patients with peripheral arterial disease. METHODS: Patients with intermittent claudication were randomized to receive ramipril or placebo for 24 weeks in a double-blind study. Outcome measures were walking distance, arterial stiffness measurement and quality of life (QoL). RESULTS: A total of 33 patients were included (25 men; mean(s.d.) age 64.6(7.8) years); 14 received ramipril and 19 placebo. After 24 weeks, ramipril improved maximum treadmill walking distance by an adjusted mean (95 per cent confidence interval, c.i.) of 131 (62 to 199) m (P = 0·001), improved treadmill intermittent claudication distance by 122 (56 to 188) m (P = 0.001) and improved patient-reported walking distance by 159 (66 to 313) m (P = 0.043) compared with placebo. Ramipril reduced carotid femoral pulse wave velocity by -1.47 (95 per cent c.i. -2.40 to -0.57) m/s compared with placebo (P = 0.002). Resting ankle : brachial pressure index (ABPI) improved slightly in both ramipril and placebo groups (0.02 (95 per cent c.i. -0.08 to 0.11) versus 0.03 (-0.05 to 0.10); P = 0.830). Ramipril had a slight, non-significant effect on QoL physical domains compared with placebo. CONCLUSION: Ramipril improved walking distance in patients with claudication; however, this improvement was not related to improved ABPI but might have been due to ramipril reducing arterial stiffness. REGISTRATION NUMBER: NCT01037530 (http://www.clinicaltrials.gov).

Aortic stiffness and vitamin D are independent markers of aortic calcification in patients with peripheral arterial disease and in healthy subjects.

OBJECTIVE: Arterial stiffness is a significant determinant of cardiovascular risk and is related to vascular calcification. Vitamin D may regulate arterial calcification and has been associated with cardiovascular survival benefits. However, data about the relationship between arterial stiffness, aortic calcification and vitamin D levels in patients with peripheral arterial disease (PAD) and in healthy subjects are limited. We examined the potential association between aortic calcification, arterial stiffness and vitamin D levels in patients with symptomatic PAD and in healthy individuals. METHODS: We studied 78 men with PAD (aged 63 ± 7 years) and 74 healthy men (aged 61 ± 10 years). Aortic pulse wave velocity (aPWV) was determined by applanation tonometry using the Sphygmocor device. Aortic calcification score (ACS) was quantified by computed tomography. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using a radioimmune assay. RESULTS: ACS (4.9(2.3-8.9) vs. 0.2(0.03-1.6) (cm³); p < 0.01), aPWV (9.8 ± 2.4 vs. 8.2 ± 1.6 (m s⁻¹; p < 0.01) and 25(OH)D (15.1 ± 5.4 vs. 19.0 ± 5.9 (ng ml⁻¹); p < 0.01) were different in the patients compared with the controls. In multivariate analysis, ACS was independently determined by 25(OH)D, aPWV, calcium and age in patients with PAD (R² = 0.49; p < 0.001) and by 25(OH)D, aPWV, cholesterol/high-density lipoprotein (HDL) and age in the control group (R² = 0.55; p < 0.001). Increased aPWV and lower levels of 25(OH)D were associated with decreased ankle-brachial pressure index (p = 0.03). CONCLUSION: These results indicate that calcification of the aorta is independently associated with aortic stiffness and serum 25(OH)D level in patients with PAD and in healthy subjects. Aortic stiffness and abnormal vitamin D level may contribute to vascular calcification and are related to higher severity grade of atherosclerotic disease.

Increased augmentation index in patients with cystic fibrosis.

Increased large artery stiffness occurs in a range of inflammatory conditions indicating an ageing of the vasculature and additionally being an independent risk factor for cardiovascular events. We determined large artery parameters in adults with cystic fibrosis (CF). 50 clinically stable adult patients with CF (mean+/-sd age 28.0+/-8.2 yrs) and 26 controls matched for age, sex and body mass index were studied. Central aortic blood pressure, augmentation index (AIx) and aortic pulse wave velocity (PWV) were determined using applanation tonometry. Lung function, diabetic status and C-reactive protein (CRP) were also determined. Mean+/-sd AIx was greater in patients than controls, 8.5+/-11.1% and -1.8+/-13.1%, respectively (p<0.001), while PWV was similar. Although AIx was greatest in the sub-group with CF-related diabetes (CFRD), it was also increased in the non-CFRD sub-group when compared with controls. In patients, AIx was related to log(10) CRP (r = 0.33) and forced vital capacity (r = -0.34; both p<0.05), and CRP remained predictive in multiple regression. AIx is increased in adults with CF, in the presence of a normal blood pressure and independent of diabetic status. AIx was related to the systemic inflammatory status. These findings have implications for management and require further exploration so that cardiovascular health can be maintained.

Cardiovascular implications of exposure to traffic air pollution during exercise.

Regular aerobic exercise is recommended by physicians to improve health and longevity. However, individuals exercising in urban regions are often in contact with air pollution, which includes particles and gases associated with respiratory disease and cancer. We describe the recent evidence on the cardiovascular effects of air pollution, and the implications of exercising in polluted environments, with a view to informing clinicians and other health professionals. There is now strong evidence that fine and ultra fine particulate matter present in air pollution increases cardiovascular morbidity and mortality. The main mechanisms of disease appear to be related to an increase in the pathogenic processes associated with atherosclerosis. People exercising in environments pervaded by air contaminants are probably at increased risk, due to an exercise-induced amplification in respiratory uptake, lung deposition and toxicity of inhaled pollutants. We make evidence-based recommendations for minimizing exposure to air-borne toxins while exercising, and suggest that this advice be passed on to patients where appropriate.

Arterial stiffness and central blood pressure, as determined by pulse wave analysis, in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is associated with increased cardiovascular mortality for reasons which are insufficiently understood. Chronic inflammation may impair vascular function and lead to an increase of arterial stiffness, an important determinant of cardiovascular risk. OBJECTIVE: To investigate the augmentation index (AIx) as a measure of arterial stiffness in patients with RA, free of cardiovascular disease or risk factors, by means of a matched cohort pilot study. METHOD: Patients with a diagnosis of RA, aged 50 years or younger, were screened for the absence of clinical cardiovascular disease and risk factors, such as smoking, hypercholesterolaemia, hypertension, and excessive systemic steroid use. Suitable subjects were assessed by non-invasive radial pulse wave analysis to determine their AIx. These data were compared with those from healthy controls, matched closely for sex, age, mean peripheral blood pressure, heart rate, and height. RESULTS: 14 suitable patients (11 female; mean (SD) age 42 (6) years, mean RA duration 11 (6) years; mean C reactive protein 19 (15) mg/l, no clinical systemic rheumatoid vasculitis) and matched controls were identified. The RA group had a higher mean (SD) AIx and mean (SD) central blood pressure (BP) than the control group: AIx 26.2 (6.7) v 18.9 (10.8)%, p=0.028; mean central BP 91.3 (7.8) v 88.2 (8.9) mm Hg, p<0.0001, by two tailed, paired t test. CONCLUSIONS: This preliminary study suggests that RA is associated with increased arterial stiffness and central BP, independently of clinically manifest cardiovascular disease or risk factors. This may contribute to the increased cardiovascular mortality in RA.

Effects of GH replacement on endothelial function and large-artery stiffness in GH-deficient adults: a randomized, double-blind, placebo-controlled study.

OBJECTIVES: Hypopituitary adults with growth hormone deficiency (GHD) have an increased cardiovascular mortality, although the mechanisms remain unclear. Endothelial dysfunction, characterized by reduced nitric oxide (NO) bioavailability, is a key early event in atherogenesis and is associated with increased vascular smooth muscle tone and arterial stiffening. DESIGN AND PATIENTS: In a randomized, double-blind, placebo-controlled study, we investigated the effects of GH replacement on endothelial function and large-artery stiffness in 32 GHD adults (19 males, 13 females) (age range 19-64 years) over a 6-month period. Thirty-two age- and sex-matched healthy controls were also studied. MEASUREMENTS: Endothelial function was assessed using ultrasonic wall tracking to measure flow-mediated dilatation (FMD) of the brachial artery. Large artery stiffness was assessed by pulse wave analysis of the radial artery pressure waveform, allowing determination of the corresponding central arterial pressure waveform and derivation of the augmentation index. Fasting lipid profiles, glucose and insulin were also measured. RESULTS: At baseline, FMD (mean +/- SD) was impaired in GH-deficient subjects vs. controls (3.4 +/- 2.3 vs. 5.7 +/- 2.0%, P < 0.0001), although endothelium-independent dilatation was similar. The augmentation index was higher in GH-deficient subjects vs. controls (23 +/- 12 vs. 14 +/- 14%, P < 0.01). GH-deficient subjects had higher LDL cholesterol (4.1 +/- 0.8 vs. 3.5 +/- 0.8 mmol/l, P < 0.01) and lower HDL cholesterol (1.1 +/- 0.3 vs. 1.4 +/- 0.4 mmol/l, P < 0.01). In GH-deficient subjects, there were inverse correlations between LDL cholesterol and FMD (r = -0.40, P < 0.05) and between FMD and the augmentation index (r = - 0.58, P < 0.01). Regression analysis identified FMD as an independent predictor of the augmentation index (P < 0.0001). In comparison with baseline, GH replacement resulted in an increase in FMD (5.0 +/- 2.6 vs. 2.8 +/- 1.9%, P < 0.01). There were decreases in central aortic systolic pressure (117 +/- 15 vs. 123 +/- 17 mmHg, P < 0.01), diastolic pressure (82 +/- 10 vs. 86 +/- 8 mmHg, P < 0.01) and the augmentation index (22 +/- 8% vs. 26 +/- 10%, P < 0.05) despite unchanged brachial pressure indices. LDL cholesterol also decreased (3.5 +/- 0.8 vs. 4.2 +/- 0.8 mmol/l, P < 0.01). There were no significant changes in the placebo group. CONCLUSIONS: Adult GHD is associated with endothelial dysfunction and increased large-artery stiffness. An improvement in endothelial function and a reduction in arterial stiffness following GH replacement suggests an important therapeutic role for GH in reducing cardiovascular risk associated with adult GHD.

The effects of induced hypogonadism on arterial stiffness, body composition, and metabolic parameters in males with prostate cancer.

Sex hormones appear to play a pivotal role in determining cardiovascular risk. Androgen deprivation therapy for males with prostate cancer results in a hypogonadal state that may have important, but as yet undetermined, effects on the vasculature. We studied the effects of androgen deprivation therapy on large artery stiffness in 22 prostate cancer patients (mean age, 67 +/- 8 yr) over a 6-month period. Arterial stiffness was assessed using pulse-wave analysis, a technique that measures peripheral arterial pressure waveforms and generates corresponding central aortic waveforms. This allows determination of the augmentation of central pressure resulting from wave reflection and the augmentation index, a measure of large artery stiffness. Body compositional changes were assessed using bioelectrical impedance analysis. Fasting lipids, glucose, insulin, testosterone, and estradiol were measured. After a 3-month treatment period, the augmentation index increased from 24 +/- 6% (mean +/- SD) at baseline to 29 +/- 9% (P = 0.003) despite no change in peripheral blood pressure. Timing of wave reflection was reduced from 137 +/- 7 to 129 +/- 10 msec (P = 0.003). Fat mass increased from 20.2 +/- 9.4 to 21.9 +/- 9.6 kg (P = 0.008), whereas lean body mass decreased from 63.2 +/- 6.8 to 61.5 +/- 6.0 kg (P = 0.016). There were no changes in lipids or glucose during treatment. Median serum insulin rose from 11.8 (range, 5.6-49.1) to 15.1 (range, 7.3-83.2) mU/liter at 1 month (P = 0.021) and to 19.3 (range, 0-85.0 mU/liter by 3 months (P = 0.020). There was a correlation between the changes in fat mass and insulin concentration over the 3-month period (r = 0.56; P = 0.013). In a subgroup of patients whose treatment was discontinued after 3 months, the augmentation index decreased from 31 +/- 7% at 3 months to 29 +/- 5% by 6 months, in contrast to patients receiving continuing treatment in whom the augmentation index remained elevated at 6 months compared with baseline (P = 0.043). These data indicate that induced hypogonadism in males with prostate cancer results in a rise in the augmentation of central arterial pressure, suggesting large artery stiffening. Adverse body compositional changes associated with rising insulin concentrations suggest reduced insulin sensitivity. These adverse hemodynamic and metabolic effects may increase cardiovascular risk in this patient group.

Adrenomedullin (ADM) in the human forearm vascular bed: effect of neutral endopeptidase inhibition and comparison with proadrenomedullin NH2-terminal 20 peptide (PAMP).

AIMS: To compare the haemodynamic responses of proadrenomedullin N-terminal 20 peptide (PAMP) and adrenomedullin (ADM) in the forearm vascular bed of healthy male volunteers, and to investigate the role of neutral endopeptidase (NEP) in the metabolism of ADM. METHODS: On two separate occasions, ADM (1-30 pmol x min(-1)) and PAMP (100-3000 pmol x min(-1)) were infused into the brachial artery of eight male subjects, and forearm blood flow (FBF) assessed using venous occlusion plethysmography. In a second study, eight male subjects received the same doses of ADM, co-infused with either the NEP inhibitor thiorphan (30 nmol x min(-1)) or the control vasoconstrictor noradrenaline (120 pmol x min(-1)), on separate occasions. Both studies were conducted in a double-blind, randomized manner. RESULTS: ADM and PAMP produced a dose-dependent increase in FBF (P < or = 0.002). Based on the dose producing a 50% increase in FBF, ADM was approximately 60 times more potent than PAMP. Thiorphan and noradrenaline produced similar reductions in FBF of 14 +/- 4% (mean +/- s.e. mean) and 22 +/- 6%, respectively (P = 0.4). However, the area under the dose-response curve was significantly greater during co-infusion of ADM with thiorphan than with noradrenaline (P = 0.028), as was the maximum increase in FBF ratio (2.1 +/- 1.0 vs 1.2 +/- 0.2; P = 0.030). CONCLUSIONS: ADM and PAMP both produce a local dose-related vasodilatation in the human forearm, but PAMP is approximately 60 times less potent than ADM. In addition, NEP inhibition potentiates the haemodynamic effects of ADM. These findings suggest that PAMP may not play a role in the physiological regulation of blood flow. However, in pathophysiological conditions such as hypertension and heart failure, NEP inhibition may exert a beneficial effect by increasing the biological activity of ADM.

Haemodynamic effects of adrenomedullin in human resistance and capacitance vessels.

AIMS: The haemodynamic effects of adrenomedullin and calcitonin gene-related peptide (CGRP) were studied in resistance and capacitance vessels of healthy volunteers. METHODS: Adrenomedullin and CGRP were infused into the brachial artery of eight healthy subjects on two separate occasions at doses between 0.3-30 pmol min(-1). Forearm blood flow was measured using venous occlusion plethysmography. Venodilatation to adrenomedullin and CGRP was assessed in a further eight subjects by infusing the peptides at doses between 0.3-10 pmol min(-1) into a dorsal hand vein preconstricted with noradrenaline. Venodilator responses were measured as percentage reduction in noradrenaline preconstriction. RESULTS: Adrenomedullin and CGRP at a dose of 30 pmol min(-1), produced an increase in forearm blood flow of 288 +/- 42% and 252 +/- 30% respectively (mean +/- s.e. mean, P<0.001). At doses between 3 and 10 pmol min(-1) adrenomedullin was significantly more potent than CGRP. The vasodilatation to both peptides was of similar duration with a biological half-life of approximately 18 min. Adrenomedullin reversed constriction in dorsal hand veins by 84 +/- 2% (P<0.001) at a dose of 10 pmol min(-1). CGRP produced a similar effect reversing constriction by 72 +/- 12% at the same dose (P<0.01). In veins, adrenomedullin was also more potent than CGRP at doses between 0.3 and 3 pmol min(-1). CONCLUSIONS: The lowest dose of adrenomedullin producing significant arteriolar dilatation was calculated to produce plasma levels similar to those found in heart failure. These findings suggest that in pathophysiological conditions such as heart failure circulating levels of adrenomedullin may be within a range capable of influencing vascular resistance directly.

Lack of effect of enalaprilat on the action of vasoactive intestinal polypeptide in the human forearm.

It has been proposed that angiotensin converting enzyme (ACE) may play a role in the metabolism of the vasodilator peptide vasoactive intestinal polypeptide (VIP). Reduced metabolism following treatment with ACE inhibitors may cause accumulation of VIP which in turn may mediate some of the beneficial haemodynamic effects of ACE inhibition observed in patients with heart failure. This study has shown that inhibition of local vascular ACE does not interfere with the vascular effects of VIP on forearm resistance vessels when this peptide is infused into the brachial artery of normal volunteers. These results suggest that endothelial ACE plays little part in the metabolism of intravascular VIP.

Pituitary adenylate cyclase activating polypeptide is a potent vasodilator in humans.

The vasodilator effect of the novel peptide pituitary adenylate cyclase activating polypeptide (PACAP) was investigated in humans. Forearm blood flow was measured in six healthy men by venous occlusion plethysmography. Infusion of PACAP into the brachial artery at 0.01, 0.1, 1, 3, and 10 pmol/min produced a dose-related increase in forearm blood flow in the cannulated arm from 2.8 +/- 0.6 to 8.6 +/- 2.4 ml/100 ml/min at the highest dose (mean +/- SEM, p less than 0.05). In a subsequent experiment, where the highest dose of PACAP was repeated after a 36 min interval, there was no tachyphylaxis of the forearm blood flow response, with the forearm blood flow increasing by 129 +/- 9% during the first infusion and 128 +/- 31% during the second infusion (N.S.). In further experiments, microvascular blood flow was measured by a laser-Doppler flow probe to compare the effects of intradermally injected PACAP, vasoactive intestinal polypeptide (VIP), and calcitonin gene-related peptide (CGRP). When injected into the skin of normal volunteers at 10(-12) to 10(-11) mol/site, each peptide caused a rapid flare lasting 2-3 min, which became erythematous after 5 min. At 10(-12) mol/site, intradermally injected PACAP and VIP caused a maximum increase in skin blood flow at 15 min of 379 +/- 96 and 307 +/- 121% (% increase above basal +/- SEM), respectively, and these responses were not significantly affected by oral aspirin (600 mg) taken 1.5 h beforehand. The vasodilation induced by PACAP at 10(-12) mol/site lasted approximately 6 h, whereas the effect of the same dose of CGRP and VIP lasted less than 2 h. These data suggest that PACAP is a potent and long-lasting vasodilator in humans.

Peptide histidine valine: its haemodynamic actions and pharmacokinetics in man differ from those of vasoactive intestinal peptide and peptide histidine methionine.

1. The effects of intravenous and intra-arterial infusion of the peptides derived from prepro-vasoactive intestinal peptide, vasoactive intestinal peptide, peptide histidine methionine and peptide histidine valine, were examined in six healthy volunteers. 2. Vasoactive intestinal peptide given intravenously caused a significant increase in heart rate and a decrease in diastolic, but not systolic, blood pressure, whereas peptide histidine valine caused an increase in heart rate alone, despite higher achieved circulating peptide concentrations. Peptide histidine methionine did not affect heart rate or blood pressure. Forearm blood flow was increased by vasoactive intestinal peptide and peptide histidine valine when infused locally intra-arterially, although vasoactive intestinal peptide was more potent than peptide histidine valine. 3. Plasma concentrations of cardiodilatin (the N-terminal peptide derived from pro-atrial natriuretic peptide) were increased by intravenous infusion of vasoactive intestinal peptide, but were unaffected by peptide histidine methionine or peptide histidine valine. Circulating plasma concentrations of adrenaline and noradrenaline did not change during infusion of vasoactive intestinal peptide, peptide histidine methionine or peptide histidine valine. 4. Peptide histidine valine had a long half-life when compared with peptide histidine methionine and vasoactive intestinal peptide. 5. We conclude that peptide histidine valine is active in the human cardiovascular system and has a similar, though less potent, vasodilating action to vasoactive intestinal peptide. The higher circulating levels of peptide histidine valine found in man suggest that it may be important in modulating vascular tone.

Location of extra-adrenal catecholamine secreting tumours by selective venous sampling and nuclear magnetic resonance scanning.

Iodinated meta-iodobenzylguanidine (MIBG) scanning is a safe non-invasive method for locating extra-adrenal paragangliomas. However, a positive result is dependent on the presence of an uptake mechanism in the tumour. We report two cases of MIBG negative intracranial catecholamine secreting tumours successfully located by selective venous sampling and nuclear magnetic resonance scanning.