Gary E Mcveigh

Belfast Health and Social Care Trust | BHSCT · Cardiovascular Department

Objective Young patients with uncomplicated hypertension are frequently exempt from statin therapy as they generally fall below current treatment thresholds. This study examined whether there may be evidence of improved microvascular function in young patients with grade 1 hypertension after 12 weeks of statin therapy. Methods This was a randomize...

The identification of pre-clinical microvascular damage in hypertension by non-invasive techniques has proved frustrating for clinicians. This proof of concept study investigated whether entropy, a novel summary measure for characterizing blood velocity waveforms, is altered in participants with hypertension and may therefore be useful in risk stra...

Far from simply lining the inner surface of blood vessels, the cellular monolayer that comprises the endothelium is a highly active organ that regulates vascular tone. In health, the endothelium maintains the balance between opposing dilator and constrictor influences, while in disease, it is the common ground on which cardiovascular risk factors a...

Statins are amongst the most investigated drugs of all time and. There is now a wealth of evidence supporting their use in both the primary and secondary prevention arenas. The reduction in event recurrence has since been demonstrated across all levels of risk and in elderly patients. As a result, it is now accepted practice for statins to be presc...

Wavelet entropy assesses the degree of order or disorder in signals and presents this complex information in a simple metric. Relative wavelet entropy assesses the similarity between the spectral distributions of two signals, again in a simple metric. Wavelet entropy is therefore potentially a very attractive tool for waveform analysis. The ability...

Structural and functional change in the microcirculation in type 1 diabetes mellitus predicts future end-organ damage and macrovascular events. We explored the utility of novel signal processing techniques to detect and track change in ocular hemodynamics in patients with this disease. 24 patients with uncomplicated type 1 diabetes mellitus, and 18...

Bone disease and ectopic calcification are the two main consequences of hyperphosphataemia of chronic kidney disease (CKD). Observational studies have demonstrated that hyperphosphataemia in CKD is associated with increased mortality. Furthermore, the use of phosphate binders in dialysis patients is associated with significantly lower mortality. Th...

Hyperkalaemia, an elevated extracellular fluid potassium concentration, is a common electrolyte disorder and is present in 1-10% of hospitalised patients. Elevated serum potassium concentrations are usually asymptomatic but may be associated with electrocardiogram (ECG) changes. Hyperkalaemia occasionally leads to life-threatening cardiac arrhythmi...

Diabetes mellitus is associated with excess cardiovascular mortality that is evident in all age groups, but is most pronounced in young people with type 1 diabetes. Cardiovascular risk estimation models generally estimate the probability of future events over a 10-year time horizon. Due to the dependency on age, children and adolescents with type 1...

The aim of this study was to compare time-domain waveform analysis of second-trimester uterine artery Doppler using the resistance index (RI) with waveform analysis using a mathematical tool known as wavelet transform for the prediction of pre-eclampsia (PE). This was a retrospective, nested case-cohort study of 336 women, 37 of whom subsequently d...

OBJECTIVE Patients with type 2 diabetes mellitus (T2DM) are at increased risk of developing cardiovascular disease, largely as a result of defective production of cardioprotective nitric oxide and a concomitant rise in oxidative stress. Dietary interventions that could reverse this trend would be extremely beneficial. Here we investigated whether d...

Diabetic retinopathy is associated with markedly increased risk of cardiovascular events. Analysis of retrobulbar blood velocity waveforms should help characterise microvessels since waveform morphology is partly determined by wave reflection. This approach could potentially allow the detection of abnormalities earlier than is currently possible. U...

Organ donation plays a major role in the management of patients with single organ failure of the kidneys, liver, pancreas, heart, or lung, or with combined organ failure of heart and lung (such as in cystic fibrosis) or of kidney and pancreas (such as in diabetes). A shortage of transplant organs has resulted in long waits for transplantation. Curr...

Microvascular changes occur early in diabetes mellitus. Doppler ultrasound enables non-invasive identification of ocular microvascular haemodynamics through interrogation of blood flow velocity waveforms. Wave decomposition permits the spectrum of sinusoidal components comprising flow velocity waveforms to be quantified. We hypothesised that compre...

Quantification of Doppler flow velocity waveforms has been shown to predict adverse cardiovascular outcomes and identify altered downstream haemodynamics and vascular damage in a number of organ beds. We employed novel techniques to quantify Doppler flow velocity waveforms from the retro bulbar circulation. In total, 39 patients with uncomplicated...

Waveform analysis has been used to assess vascular resistance and predict cardiovascular events. We aimed to identify microvascular abnormalities in patients with IGT using ocular waveform analysis. The effects of pioglitazone were also assessed. Forty patients with IGT and 24 controls were studied. Doppler velocity recordings were obtained from th...

The earliest signs of cardiovascular disease occur in microcirculations. Changes to mechanical and structural properties of these small resistive vessels alter the impedance to flow, subsequent reflected waves, and consequently, flow waveform morphology. In this paper, we compare two frequency analysis techniques: 1) rootMUSIC and 2) the discrete w...

Flow-mediated dilatation (FMD) of the brachial artery is commonly measured as a surrogate marker of endothelial function. Its measurement is, however, technically demanding and reports regarding its reproducibility have not always been favourable. Two Type I diabetes and control group comparator studies were conducted to assess the reproducibility...

Impaired FMD (flow-mediated dilatation) has traditionally been recognized as an indirect marker of NO bioactivity, occurring in disease states such as DM (diabetes mellitus). Endothelium-dependent FMD is a homoeostatic response to short-term increases in local shear stress. Microvascular dysfunction in DM influences blood flow velocity patterns. We...

Disturbances to the cellular production of nitric oxide (NO) and superoxide (O(2)(-)) can have deleterious effects on retinal vascular integrity and angiogenic signaling. Dietary agents that could modulate the production of these signaling molecules from their likely enzymatic sources, endothelial nitric oxide synthase (eNOS) and NADPH oxidase, wou...

HMG Co-A reductase inhibitors (statins) are a group of drugs which lower cholesterol by inhibiting the conversion of HMG Co-A to mevalonate early in the cholesterol synthetic pathway. They are used in the primary and secondary prevention of cardiovascular events in patients deemed to be at increased risk and their benefit in patients with ischaemic...

Flow-mediated dilation (FMD) is a surrogate marker of endothelial function, which has been proposed as a barometer of vascular health. Impaired microvascular response to reactive hyperaemia is thought to be the mechanism behind reduced shear stress and subsequently impaired FMD, which has been associated with cardiovascular events. This study aims...

In addition to lowering cholesterol, statins may alter endothelial release of the vasodilator NO and harmful superoxide free radicals. Statins also reduce cholesterol intermediates including isoprenoids. These are important for post-translational modification of substances including the GTPases Rho and Rac. By altering the membrane association of t...

We assessed whether quantitative analysis of Doppler flow velocity waveforms is able to identify subclinical microvascular abnormalities in SLE and whether eigenvector analysis can detect changes not detectable using the resistive index (RI). Fifty-four SLE patients with no conventional cardiovascular risk factors, major organ involvement or retino...

Clinical and experimental studies indicate that structural and functional changes in the microvasculature can predate or accompany risk factors for cardiovascular disease at the earliest stages in the disease process. In the current work, both simulated and actual Doppler ultrasound maximum blood velocity waveform envelopes recorded from the ophtha...

Risk factors for cardiovascular disease mediate their effects by altering the structure and function of wall and endothelial components of arterial blood vessels. A pathological change in the microcirculation plays a pivotal role in promoting end-organ dysfunction that not only predisposes to further organ damage, but also increases the risk for fu...

To determine the clinical effect of dietary supplementation with low-dose omega-3-polyunsaturated fatty acids on disease activity and endothelial function in patients with systemic lupus erythematosus. A 24-week randomised double-blind placebo-controlled parallel trial of the effect of 3 g of omega-3-polyunsaturated fatty acids on 60 patients with...

Diabetes mellitus is a potent risk factor for the development of a wide spectrum of cardiovascular (CV) complications. The complex metabolic milieu accompanying diabetes alters blood rheology, the structure of arteries and disrupts the homeostatic functions of the endothelium. These changes act as the substrate for end-organ damage and the occurren...

We present two clinical cases from a single institution where a final diagnosis of cardiac failure was made following the initial finding of ascites and an elevated CA 125 level. In both cases gynaecological malignancy was initially suspected. Following negative confirmatory tests for gynaecological malignancy, echocardiography was undertaken. Pati...

Thiazolidinediones (TZDs) have been used for the treatment of hyperglycaemia in type 2 diabetes for the past 10 years. They may delay the development of type 2 diabetes in individuals at high risk of developing the condition, and have been shown to have potentially beneficial effects on cardiovascular risk factors. TZDs act as agonists of peroxisom...

Most traditional cardiovascular risk factors alter the structure and/or function of arteries. An assessment of arterial wall integrity could therefore allow accurate prediction of cardiovascular risk in individuals. The term 'arterial stiffness' denotes alterations in the mechanical properties of arteries, and much effort has focused on how best to...

Structural and functional changes in wall and endothelial components of arterial blood vessels underlie the accelerated vascular disease progression in systemic lupus erythematosus (SLE). Using pulse contour analysis we sought to determine if subclinical vascular abnormalities could be identified in a well-characterised cohort of patients with SLE...

The constituents of the walls of blood vessels make them compliant. Their compliance is demonstrated by the relationship between transmural pressure and vessel diameter. Arteries, in contrast to veins, exhibit a steep pressure/volume relationship indicative of less compliant vessels. The compliance characteristics of these vessels relate to their i...

Impaired flow-mediated dilation (FMD) occurs in disease states associated with atherosclerosis, including SLE. The primary hemodynamic determinant of FMD is wall shear stress, which is critically dependent on the forearm microcirculation. We explored the relationship between FMD, diastolic shear stress (DSS), and the forearm microcirculation in 32...

Dysfunction of the endothelium and of the arterial wall is well described in patients with atherosclerosis, diabetes, and other risk factors for vascular disease. In recent years, clinical research has focused on elucidating the role of this dysfunction in influencing vascular disease progression. Alteration in the structure of arteries and disrupt...

Quantitative analysis of the arterial pressure pulse waveform recorded by applanation tonometry of the radial artery can track NO (nitric oxide)-mediated modulation of arterial smooth muscle tone. The changes in pressure pulse waveform morphology result from pulse wave reflection arising predominantly from smaller arteries and arterioles. Employing...

We investigated the effects of omega-3 fatty acids administration on endothelium-dependent vasodilation in patients > or =65 years old who received treatment for chronic heart failure (CHF). Twenty patients (mean age 73 years; 15 men) with grade II and III CHF who were on maximal medical management were recruited. Patients were randomized in a doub...

Vascular NAD(P)H oxidase represents a major source for excessive superoxide production in hypertension. Angiotensin II (AngII) can activate NAD(P)H oxidase via the angiotensin II type 1 (AT1) receptor and protein kinase C (PKC). Platelets possess AT1 receptors and all the components of the NAD(P)H oxidase system. We employed this tissue model to ex...

Hypertension and diabetes are important independent risk factors for increased oxidative stress and increased cardiovascular risk. The combination of hypertension and diabetes results in a dramatic increase in cardiovascular risk. Enhanced oxidative stress in hypertension and diabetes is linked to decreased nitric oxide (NO) bioavailability because...

We determined the reliability and repeatability of measurements of arterial compliance (AC) and gender- and age-specific normal ranges for a healthy European population. Three hundred eight healthy volunteers from seven sites were evaluated. Two measurements were taken during the first visit, repeated on a second visit 1 to 4 weeks later. We used t...

Impaired endothelium-dependent and independent vasodilator responses in chronic heart failure (CHF) have been well described. Previous studies involved younger patients and omitted medications prior to study. We explored if new therapeutic interventions would restore vasodilator responses in typical patients with chronic heart failure. 24 patients...

Alteration in the physical properties of arterial blood vessels act as the substrate for end-organ damage and the occurrence of vascular events in hypertension. Structural and functional alteration in the microcirculation represents a prevalent and characteristic abnormality described in the earliest stages of hypertension. In addition to lowering...

To evaluate the effects of the intravenous administration of the nitric oxide synthesis inhibitor N(g)nitro-L-arginine methyl ester (L-NAME) in healthy volunteers. L-NAME (0.25, 0.5 and 0.75 mg/kg over 8 min) was infused in 13 healthy male volunteers. Finally, subjects were infused with either L- or D-arginine. L-NAME resulted in dose-dependent fal...

Impaired endothelium-mediated vasodilatation (EMVD) in congestive cardiac failure (CCF) has been linked to decreased nitric oxide (NO) bioavailability because of its interaction with vascular superoxide (O2*-), derived predominantly from NAD(P)H-dependent oxidases. When uncoupled from essential cofactors, endothelial nitric oxide synthase (eNOS) pr...

Our purpose was to compare arterial elasticity (AE) in healthy European adults according to their family history of hypertension and stroke. AE parameters were measured using the HDI/PulseWave™ CR-2000 Cardiovascular Profiling System in 308 healthy European adults between the ages of 15 and 80 years with a BMI of less than 30 kg/m². Participants we...

The purpose of the present study was to estimate, arterial elasticity (AE) in healthy subjects for repeatability and reliability and to establish the normal values for AE in healthy European population with comparison to values established for healthy US population. In a controlled prospective study the reproducibility of AE parameters using the HD...

Our purpose was to compare arterial elasticity (AE) in wine drinkers (up to one glass per day) to non-drinkers in healthy European population. AE parameters were measured using the HDI/PulseWave“ CR-2000 Cardiovascular Profiling System in 243 healthy subjects in which all relevant information was present, out of 308 subjects that were studied. All...

The metabolic syndrome is a highly prevalent multifaceted clinical entity produced through the interaction of genetic, hormonal, and lifestyle factors. A distinctive constellation of abnormalities precedes and predicts the accelerated development of inflammation and coagulation represent emerging risk contributors associated with obesity and insuli...

The haemodynamic consequence of altered mechanical wall properties in diabetes can impair the compliance characteristics or pulsatile function of arteries before changes in calibre or peripheral resistance become evident. We studied the sensitivity of pulsatile and steady-state haemodynamic variables in identifying vascular abnormalities and assess...

The objective of this study was, using isolated platelets as a surrogate for vascular cells, to examine the effect of nonintermittent organic nitrate administration on 8-epi prostaglandin F(2alpha) (8-epi PGF(2alpha)) content and the effect of concurrent oral ascorbate administration. The long-term efficacy of organic nitrates is hampered by hemody...

The therapeutic benefits that accompany the continuous administration of organic nitrates are attenuated by the development of tolerance to the compounds. Altered superoxide production and NO bioavailability have been implicated in contributing to the development of tolerance, an effect that may be ameliorated by the administration of antioxidants....

Inhibiting platelet and endothelial nitric oxide production favours platelet adhesion and aggregation, and arterial vasoconstriction. This study investigated the effect of NG-nitro-l-arginine methyl ester (L-NAME), a stereospecific inhibitor of nitric oxide synthesis, on P-selectin expression on platelets, platelet-derived microparticles and platel...

Ageing and disease states associated with an increase in cardiovascular events alter the physical characteristics of blood vessel walls and impair the pulsatile function of arteries. An accumulating body of evidence indicates that impaired pulsatile function of arteries provides important prognostic and therapeutic information beyond that provided...

The primary aim in the medical treatment of hypertension is to lower blood pressure (BP). A wide variety of agents have proved effective for meeting this goal. However, an ideal agent for management of hypertensive patients must also meet a number of additional criteria. It should have a significant positive impact on conditions that are likely to...

Arterial compliance measurements using intraarterial pulse contour analysis and a modified Windkessel model were carried out in 19 patients with isolated systolic hypertension (> or = 160/< or = 90 mm Hg) and compared to measurements in 29 patients with essential hypertension (diastolic blood pressure [BP] > or = 95 mm Hg) and 47 normotensive contr...

Traditionally, nitric oxide-mediated alteration in blood vessel tone has been inferred from changes in flow in response to physical and pharmacological interventions using plethysmographic or ultrasonic techniques. We hypothesized that alteration in pulsatile arterial function may represent a more sensitive measure to detect and monitor nitric oxid...

The aim of this study was to assess the relation between blood pressure (BP) and arterial compliance in a healthy sample of young adults. School children (aged 10 to 14 years at entry) were surveyed in 1977 to 1978, and 1207 were followed once to twice yearly until age 23 years. Arterial compliance was measured in 179 adults at the last follow-up v...

The aim of this study was to assess the relation between blood pressure (BP) and arterial compliance in a healthy sample of young adults. School children (aged 10 to 14 years at entry) were surveyed in 1977 to 1978, and 1207 were followed once to twice yearly until age 23 years. Arterial compliance was measured in 179 adults at the last follow-up v...

Our results confirm a higher early neonatal mortality in low risk babies born at night. This may be a result of staff's increased physical and mental fatigue during the night, when doctors in charge, at least in Germany, have usually worked through a complete day shift. Overreliance on less experienced staff may be another important reason for the...

The objective of this study was to evaluate age-related changes in pulsatile arterial function. Aging alters arterial pulsatile function and produces consistent changes in the pressure pulse contour. A reduced systemic arterial compliance that can be derived from analysis of the pulse contour is regarded as the best clinical index of impaired pulsa...

Arterial compliance, defined as a change in dimension in response to a given change in stress, is becoming an increasingly important clinical parameter. Related concepts, such as distensibility, elasticity, and stiffness, and more traditional concepts such as resistance, afterload, and impedance need to be differentiated from compliance, although t...

Consistent changes in the arterial pulse contour are found with aging and disease states that impair the compliance characteristics of blood vessels that buffer pulsatile phenomena in the arterial tree. We assessed whether vascular adaptation in structure or tone of blood vessels associated with long-term cigarette smoking would influence steady st...

Endothelial injury is a central feature of vascular disease induced by cigarette smoking and may act as a precursor for future atherosclerosis. Using forearm occlusion plethysmography, we studied the vascular responses to methacholine (an endothelium-dependent vasodilator) and sodium nitroprusside (an endothelium-independent vasodilator) infused in...

EDITOR,—In 1992 we published a study showing that endothelium dependent and endothelium independent vasodilatation was impaired in 29 patients with non-insulin dependent diabetes compared with 21 controls matched for age and sex.1 The vasodilator responses to acetylcholine and glyceryl trinitrate were impaired, as was arterial compliance, which was...

Lipid peroxidation may be important in the development of cardiovascular disease, a common cause of mortality and morbidity in non-insulin dependent diabetes mellitus (NIDDM). We assessed the degree of lipid peroxidation by measuring plasma malondialdehyde, as thiobarbituric acid reacting substances (TBARS), in 23 non-insulin diabetic patients. Pla...

Alterations in the structure and function of large and small arterial vessels occur in hypertension and diabetes mellitus. These changes influence the tone and reactivity of the arteries, accelerate the atherogenic process and account for the vascular complications associated with the diseases. The widespread changes throughout the systemic circula...