Andrew J.M. Broadley

Arterial endothelial function is impaired in treated depression

Objectives: To determine whether patients with treated depression but no other risk factors for coronary heart disease (CHD) have abnormal arterial endothelial function, an abnormality that is common to other acquired risk factors for CHD. Design: Case–control study. Setting: Secondary care departments of cardiology and psychiatry in a single centre and the surrounding community. Participants: Patients with treated depression and matched healthy controls, aged 18–55 years, without conventional acquired risk factors for CHD. These were recruited from local community mental health clinics, general practices, and patient support groups, and through posters placed in public areas of the hospital. Patients had major depression as defined in the American Psychiatric Association’s Diagnostic and statistical manual of mental disorders, fourth edition. Fifteen patients and 12 controls were recruited, and 12 patients and 10 controls completed the study. Outcomes: Brachial artery flow mediated dilatation and baroreflex sensitivity. Results: Arterial endothelial function measured by flow mediated dilatation was impaired in depression (mean (SEM) −0.7% (1.7%)) compared with controls (5.7% (0.9%), p = 0.005 by non-paired t test). Baroreflex sensitivity did not differ significantly between the groups. Conclusion: Arterial endothelial function is impaired in treated depression. This abnormality may contribute to the increased risk of CHD seen in depression.

Baroreflex sensitivity is reduced in depression

Objectives: Depression is independently associated with increased cardiovascular morbidity and mortality, including sudden cardiac death, and this risk is observed even in patients who have been successfully treated for depression. Recent studies have emphasized the importance of impaired baroreceptor sensitivity (BRS) as a predisposing factor for sudden death in patients with manifest cardiac disease. Our objective was to test the hypothesis that BRS is impaired in subjects with depression in remission and with no other cardiac risk factors. Methods: We measured BRS by the sequence method in 36 patients with treated recurrent depression, who were euthymic at the time of study and with no manifest cardiac disease or “conventional” cardiac risk factors, compared with 39 healthy controls. Exclusion criteria included manifest heart disease or any risk factor for IHD (smoking, hypertension, diabetes, hypercholesterolemia, or body mass index >30). Nine subjects were not on any medication, and 22 were taking antidepressants. None of the controls was taking any medication. Results: BRS was significantly lower in patients than in controls (19.5 [1.78] versus 25.4 [1.69] ms/mm Hg, p = .017). Analysis of covariance, in which age, sex, cholesterol, and body mass index were included, also showed that depression was a significant (p = .027) predictor of BRS. There was no significant difference in BRS adjusted by age and sex between the subjects taking antidepressants compared with those on no medications (p = .40). Conclusions: These data indicate that BRS is impaired in otherwise healthy patients with depression and may contribute to their increased cardiac risk. IHD = ischemic heart disease; MI = myocardial infarction; SSRI = selective serotonin reuptake inhibitor; HR = heart rate; BP = blood pressure BRS = baroreflex sensitivity; ANCOVA = analysis of covariance.

Effects of exogenous and endogenous natriuretic peptides on forearm vascular function in chronic heart failure

Objective—Natriuretic peptides (NPs) reduce central venous pressure in patients with chronic heart failure (cHF) despite attenuation of arterial, renal, and humoral effects. This suggests a preserved venodilator response. This study had 4 aims: to compare the venodilator effects of human NPs in patients with cHF; to assess the contribution of basal ANP and BNP levels to regulation of forearm vascular volume (FVV); to test the hypothesis that venous ANP responsiveness is preserved in cHF; and to assess the involvement of endothelial nitric oxide-synthase (eNOS) in NP-induced vascular effects. Methods and Results—Venous and arterial forearm vascular responses to incremental intra-arterial doses of ANP, Urodilatin, BNP, CNP, or the ANP receptor antagonist A71915 were studied in 53 patients and 11 controls. ANP receptor antagonism reduced FVV by 4.4%±1.2% (P<0.05). The forearm blood flow (FBF) response to ANP was significantly blunted in patients versus controls (P<0.01), whereas FVV increased similarly in both groups (maximum 14.7% and 13.4%, both P<0.001). The eNOS blockade reduced ANP-induced FBF changes in controls but not in patients (P<0.05), whereas similar reductions in FVV changes were seen in groups (both P<0.001). Conclusions—In cHF venous, but not arterial, ANP responsiveness is preserved. Arterial endothelial dysfunction may contribute to NP resistance.

Atrial Natriuretic Peptide Regulates Regional Vascular Volume and Venous Tone in Humans

Objective—To date, the contribution of basal atrial natriuretic peptide (ANP) levels to resting vascular function in humans is unknown. In the present study we sought to investigate the role of ANP in regulating regional vascular volume and venous tone in healthy subjects. Methods and Results—We used radionuclide plethysmography to examine the effects of ANP and the ANP-receptor antagonist A71915 on forearm vascular volume. Creating pressure/volume relations, we determined changes in vascular volume, compliance, and tone. Performing dose-ranging studies, we additionally assessed the potency and specificity of A71915 in the forearm resistance vasculature. Equilibrium blood pool scintigraphy was then used to assess the effects of systemic administration of A71915 on regional intestinal vascular volume. Infusion of ANP increased forearm vascular volume in a dose-dependent manner (maximum 20%; P <0.001), exerting a maximum venodilating effect at plasma levels similar to that seen in heart failure. A71915 increased venous tone, thereby decreasing vascular volume by 9.6±1.1%, P <0.001 (forearm), and 2.6±0.5%, P =0.01 (intestinal beds). At an infusion ratio of 50:1, A71915 almost completely abolished the effects of ANP on forearm blood flow. Conclusions—ANP locally regulates regional vascular volume and tone without affecting compliance.

Inhibition of platelet aggregation by nitric oxide donors improves with rest

It has been suggested that the platelets of patients with acute coronary syndromes (ACS) exist in a more activated state than those of patients with stable coronary heart disease (CHD) or healthy individuals. “Platelet nitrate responsiveness” (PNR) has been suggested as a measure of platelet activation, and has been shown to be reduced in both ACS and stable CHD. We examined the effect of a short period of undisturbed supine rest, an intervention aimed at reducing levels of “stress”, on PNR. In 8 healthy subjects we found that 45 minutes of rest led to a highly significant reduction in platelet aggregation and increase in PNR. Our finding supports the hypothesis that stress contributes to platelet activation as reflected in reduced PNR, which may contribute to the link between acute stress and cardiovascular events. It also emphasises that standardisation of sampling conditions in vitally important in studies utilizing PNR.