David B. Northridge
Western General Hospital
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Featured researches published by David B. Northridge.
Clinical Radiology | 2003
S.J Cowell; David E. Newby; J Burton; Audrey White; David B. Northridge; N.A Boon; John H. Reid
AIM Incidental aortic valve calcification is often detected during computed tomography. The aim was to compare the severity of valvular stenosis and calcification in patients with aortic stenosis. MATERIALS AND METHODS One hundred and fifty-seven patients aged 68+/-11 years (range: 34-85) with aortic valve stenosis underwent multislice helical computed tomography and Doppler echocardiography performed by independent, blinded observers. The aortic valve calcium score was determined using automated computer software calibrated with a phantom. RESULTS Doppler echocardiography demonstrated a post-valve velocity of 3.45+/-0.66 m/s and a peak gradient of 49+/-11 mmHg. Computed tomography showed excellent reproducibility and the median aortic valve calcium score was 5858 AU (interquartile range, 1555-14,596). The computed tomography aortic valve calcium score positively correlated with the Doppler post-valve velocity and peak gradient (r=0.54, p<0.0001 for both) of the aortic valve. All patients with severe aortic stenosis had a calcium score of >3700 AU. CONCLUSION Calcification of the aortic valve is closely associated with the severity of aortic stenosis, and heavy calcification suggests the presence of severe aortic stenosis that requires urgent cardiological assessment. Patients with lesser degrees of aortic valve calcification should be screened for aortic stenosis and monitored for disease progression.
Journal of Hypertension | 2004
Andrew L. McLeod; Neal G. Uren; Ian B. Wilkinson; David J. Webb; Simon Maxwell; David B. Northridge; David E. Newby
Objective Arterial stiffness is an emerging major risk factor for cardiovascular morbidity and mortality. The aim of the present study was to assess if coronary artery plaque load correlates with non-invasive measures of arterial stiffness. Design Prospective investigational study. Setting Tertiary university hospital centre. Patients Patients undergoing elective diagnostic coronary angiography. Interventions and main outcome measures Coronary artery plaque burden was assessed using a 30 MHz intravascular ultrasound catheter during an automated pullback. Proximal coronary artery plaque volume was determined using a validated edge-detection algorithm following three-dimensional computerized reconstruction. Central arterial stiffness was assessed in each patient using applanation tonometry to radial, carotid and femoral pulses, with derivation of aortic pressure augmentation and pulse wave velocity using pulse wave analysis. Results In 35 patients (61 ± 2 years), proximal coronary arterial plaque volume was 5.9 ± 0.6 mm3/mm of vessel. Plaque volume correlated positively with carotid-radial pulse wave velocity (r = 0.47, P = 0.008) and appeared to correlate with carotid–femoral pulse wave velocity (r = 0.34, P = 0.07). Aortic augmentation (r = 0.24, P = 0.16), augmentation index (r = 0.3, P = 0.08), and pulse pressure (r = 0.22, P = 0.2) did not correlate significantly with proximal coronary artery plaque volume. Conclusions Non-invasive measures of carotid-radial pulse wave velocity correlate with the extent of coronary artery plaque volume and may be a useful non-invasive surrogate marker for the extent of coronary atherosclerosis. Our findings are consistent with the suggestion that central aortic stiffness may promote the development of coronary atherosclerosis and ischaemic heart disease.
American Heart Journal | 1999
David B. Northridge; David E. Newby; Ester Rooneyb; John Norrie; Henry J. Dargie
BACKGROUND Candoxatril is a novel neutral endopeptidase inhibitor that increases plasma concentrations of atrial natriuretic factor and thereby produces natriuresis, diuresis, and vasorelaxation. This profile of action offers theoretical advantages over standard diuretic therapy in the treatment of patients with heart failure. The aims of the study were to compare the effects of candoxatril with those of frusemide in the treatment of patients with mild heart failure. METHODS Male patients with mild heart failure were randomly assigned to 9 days of therapy with 20 mg frusemide twice a day, 200 mg candoxatril twice a day, or 400 mg candoxatril twice a day (n = 10 per group) after a 14-day placebo washout phase. Systemic hemodynamic measurements, exercise tolerance, and urinary and plasma hormone concentrations were assessed during the placebo run-in and at the beginning and end of the double-blind therapy. RESULTS Frusemide and candoxatril caused similar diuresis and natriuresis. Candoxatril caused a slight decrease in systolic blood pressure and a dose-dependent increase in plasma and urinary concentrations of atrial natriuretic factor without elevating plasma renin activity. Frusemide reduced plasma concentrations of atrial natriuretic factor and increased plasma renin activity. Treadmill exercise capacity decreased 30 +/- 26 seconds after use of frusemide, compared with increases of 12 +/- 35 seconds after use of 200 mg candoxatril twice a day and 35 +/- 31 seconds after use of 400 mg candoxatril twice a day (P =.13; frusemide versus 400 mg candoxatril twice a day). CONCLUSIONS In the treatment of patients with mild heart failure, candoxatril has diuretic effects equivalent to those of 20 mg frusemide twice a day without the associated and potentially detrimental activation of the renin-angiotensin-aldosterone system. The trend for improved exercise capacity with candoxatril warrants further investigation.
European Journal of Heart Failure | 1999
David B. Northridge; Peter F. Currie; David E. Newby; John J.V. McMurray; Michael Ford; Nicholas A. Boon; Henry J. Dargie
To compare the effects on exercise capacity of the neutral endopeptidase inhibitor candoxatril, and the angiotensin converting enzyme inhibitor captopril, in patients with mild to moderate heart failure.
Cardiovascular Research | 2003
Andrew L. McLeod; David E. Newby; David B. Northridge; Keith A.A. Fox; Neal G. Uren
OBJECTIVES Arterial remodeling may increase or decrease the luminal encroachment of atherosclerotic plaques in the coronary circulation. However, the factors determining the nature and consequences of the remodeling process remain poorly characterized. The study aims were to assess whether the pattern of vascular remodeling influences the physical and vasomotor responses of the coronary arteries in vivo in man. METHODS Coronary vessel area, distensibility and stiffness were determined in positively, negatively and non-remodeled arterial segments using intravascular ultrasound and Doppler flow measurement. Epicardial vasomotor responses were determined following intracoronary boluses of acetylcholine (10(-6) and 10(-4) M), adenosine (24-30 microg) and nitroglycerin (200 microg). RESULTS Fifty-six coronary arterial segments were studied in 25 patients. In comparison to non- and positively remodeled segments, negatively remodeled segments had a higher stiffness index (67+/-16 vs. 33+/-5 and 38+/-8, respectively; P<0.02) and appeared to have lower compliance and distensibility (0.66+/-0.17 vs. 1.65+/-0.54 and 0.94+/-0.18/mmHg; P=NS). Non-remodeled segments had a greater change in vessel area with 10(-6) M acetylcholine (4.9+/-0.8%), compared to positively and negatively remodeled segments (0.6+/-1.8% and -4.9+/-1.8%, respectively, P<0.05). A significant degree of preservation of vasodilatation to 10(-6) M acetylcholine was evident in positively remodeled compared with negatively remodeled segments (P<0.05). Nitroglycerin caused greater vasodilatation in non-remodeled segments (7.2+/-3.8%) than either positively or negatively remodeled segments (4.7+/-0.9 and 3.7+/-0.6%, respectively, P<0.05). CONCLUSIONS Vascular remodeling is an important and major determinant of local epicardial vasomotor responses. Both structural and functional abnormalities are associated with negative remodeling that may contribute to the adverse effects of such lesions.
Catheterization and Cardiovascular Interventions | 2017
William Wilson; Anoop Shah; Duncan Birse; Emma Harley; David B. Northridge; Neal G. Uren
Fractional flow reserve (FFR) allows for physiological definition of coronary lesion severity but requires induction of maximal coronary circulation hyperemia with administration of adenosine leading to coronary resistive vessel vasodilatation. However, the hyperemic response to adenosine, and therefore the calculation of FFR, may be affected by dysfunction of the coronary microvasculature. The aim was to define the relationship between basal Pd/Pa and FFR and identify lesion‐independent predictors of the change in Pd/Pa with hyperemia.
Coronary Artery Disease | 2003
Nicholas Palmer; Alistair Lessells; David B. Northridge; Keith A.A. Fox
Background Following percutaneous transluminal coronary angioplasty (PTCA), the extent of vascular injury is underestimated by angiographic assessment. Conventional intracoronary ultrasound (ICUS) imaging provides additional information with regard to the extent of dissections but requires mental reconstruction of consecutive images. Three‐dimensional ICUS reconstruction overcomes this limitation and may provide more accurate assessment of the extent of vascular injury. This study compares conventional two‐dimensional ICUS imaging to combined two‐ and three‐dimensional ICUS information in the assessment of vascular injury following PTCA. Methods Atherosclerotic, human coronary arteries (n =24) were studied in a specially constructed flow system. Balloon dilatation of significant stenoses was performed followed by assessment using two‐ and three‐dimensional ICUS imaging methods. Treated arteries were submitted for histological assessment after pressure fixation. Dissection depth and length measurements were made from obtained images and compared to histomorphometric assessments. Results Of the 20 arterial segments confirmed histologically to contain dissection, 11 (55%) and 18 (90%) were identified by two‐dimensional ICUS and combined twoand three‐dimensional ICUS respectively. The k values for correlation of dissection type were 0.29 (0.23‐0.35) and 0.64 (0.57‐0.71) respectively indicating better agreement using combined two‐ and three‐dimensional ICUS. Twodimensional ICUS consistently underestimated dissection length (3.52 ±1.75 mm compared with 6.54 ±2.42 mm, P < 0.001) and depth (0.61± 0.24mm compared with 0.92 ±0.32 mm, P = 0.001). Combined two‐ and threedimensional ICUS produced accurate dissection length (6.13 ±2.29mm compared with 6.54± 2.42 mm, P = 0.09) and depth (0.86 ±0.32mm compared with 0.92 ± 0.32 mm, P = 0.28) estimations. Conclusion Computerized three‐dimensional reconstruction of ICUS images provides improved accuracy compared to conventional ICUS imaging in the detection and quantitation of arterial dissection. This technique would be a useful adjunct to angiography for the precise assessment of vascular injury following PTCA. Coron Artery Dis 14:255‐262
Case Reports | 2009
Rustam Al-Shahi Salman; David B. Northridge; Alastair N J Graham; Robin Grant
Cardioembolic stroke is an important cause of stroke in young people. Cardioembolism classically causes infarcts in multiple vascular territories. In the case described here a young woman developed cardioembolic stroke secondary to atrial myxoma. The presentation was atypical in that the woman had no systemic manifestations of her myxoma.
The New England Journal of Medicine | 2005
S. Joanna Cowell; David E. Newby; Robin Prescott; Peter Bloomfield; John H. Reid; David B. Northridge; Nicholas A. Boon
BMJ | 1986
David B. Northridge; John J.V. McMurray; A. A. H. Lawson