PubMed Health⌕ Search

Biomedical subjects

D B Northridge

Publications and source records attributed to D B Northridge.

At least 19 recordsLinked to original sources
PubMed2006

Progressive coronary calcification despite intensive lipid-lowering treatment: a randomised controlled trial.

OBJECTIVES: To evaluate the effect of intensive lipid-lowering treatment on coronary artery calcification in a substudy of a trial recruiting patients with calcific aortic stenosis. METHODS: In a double blind randomised controlled trial, 102 patients with calcific aortic stenosis and coronary artery calcification were randomly assigned by the minimisation technique to atorvastatin 80 mg daily or matched placebo. Coronary artery calcification was assessed annually by helical computed tomography. RESULTS: 48 patients were randomly assigned to atorvastatin and 54 to placebo with a median follow up of 24 months (interquartile range 24-30). Baseline characteristics and coronary artery calcium scores were similar in both groups. Atorvastatin reduced serum low density lipoprotein cholesterol (-53%, p < 0.001) and C reactive protein (-49%, p < 0.001) concentrations whereas there was no change with placebo (-7% and 17%, p > 0.95 for both). The rate of change in coronary artery calcification was 26%/year (0.234 (SE 0.037) log arbitrary units (AU)/year; n = 39) in the atorvastatin group and 18%/year (0.167 (SE 0.034) log AU/year; n = 49) in the placebo group, with a geometric mean difference of 7%/year (95% confidence interval -3% to 18%, p = 0.18). Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r = 0.05, p = 0.62). CONCLUSION: In contrast to previous observational studies, this randomised controlled trial has shown that, despite reducing systemic inflammation and halving serum low density lipoprotein cholesterol concentrations, statin treatment does not have a major effect on the rate of progression of coronary artery calcification.

Adult↗
PubMed2005

Direct comparison of selective endothelin A and non-selective endothelin A/B receptor blockade in chronic heart failure.

OBJECTIVE: To investigate the potential differential effects of selective endothelin (ET) A and dual ET-A/B receptor blockade in patients with chronic heart failure. METHODS: Nine patients with chronic heart failure (New York Heart Association class II-III) each received intravenous infusions of BQ-123 alone (selective ET-A blockade) and combined BQ-123 and BQ-788 (dual ET-A/B blockade) in a randomised, placebo controlled, three way crossover study. RESULTS: Selective ET-A blockade increased cardiac output (maximum mean (SEM) 33 (12)%, p < 0.001) and reduced mean arterial pressure (maximum -13 (4)%, p < 0.001) and systemic vascular resistance (maximum -26 (8)%, p < 0.001), without changing heart rate (p = 0.38). Dual ET-A/B blockade significantly reduced the changes in all these haemodynamic variables compared with selective ET-A blockade (p < 0.05). Selective ET-A blockade reduced pulmonary artery pressure (maximum 25 (7)%, p = 0.01) and pulmonary vascular resistance (maximum 72 (39)%, p < 0.001). However, there was no difference between these effects and those seen with dual ET-A/B blockade. Unlike selective ET-A blockade, dual ET-A/B blockade increased plasma ET-1 concentrations (by 47 (4)% with low dose and 61 (8)% with high dose, both p < 0.05). CONCLUSIONS: While there appeared to be similar reductions in pulmonary pressures with selective ET-A and dual ET-A/B blockade, selective ET-A blockade caused greater systemic vasodilatation and did not affect ET-1 clearance. In conclusion, there are significant haemodynamic differences between selective ET-A and dual ET-A/B blockade, which may determine responses in individual patients.

Adult↗
PubMed2003

Aortic valve calcification on computed tomography predicts the severity of aortic stenosis.

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.

Adult↗
PubMed2002

Myocardial infarction following the combined recreational use of Viagra and cannabis.

Sildenafil citrate (Viagra, Pfizer, Inc., New York, N.Y.) is widely prescribed as a treatment for male erectile dysfunction. It is metabolized predominantly by the cytochrome P450 3A4 hepatic microsomal isoenzyme and effects can, therefore, be potentiated by such inhibitors. The vasodilatory effects of Viagra necessitate caution in its use in patients with cardiovascular disease and it is contraindicated in patients receiving nitrates. Previous literature has drawn attention to Viagra use and myocardial infarction. This paper reports the case of a young man who presented with a myocardial infarction after taking Viagra in combination with cannabis, a known inhibitor of the cytochrome P450 3A4 isoenzyme.

Adult↗
PubMed2000

In-hospital resource utilization in coronary angioplasty: the impact of increased coronary stenting rates and antiplatelet therapy.

BACKGROUND: The technique of coronary stenting has evolved over recent years, with improved stent technology and effective antiplatelet therapies to prevent stent thrombosis. In Europe, reductions in stent and equipment costs have resulted from increased market competition. The impact of these changes on the in-hospital procedural cost of percutaneous coronary intervention (PCI) in the current clinical setting is not known. METHODS: We compared the initial equipment and pharmaceutical costs of one hundred consecutive, unselected patients undergoing PCI in 1998 to a similar population who underwent PCI in 1994. RESULTS: Similar patient characteristics were noted, yet more complex disease (multivessel, AHA type B2/C lesions) was treated in the 1998 population. The stent utilization rate (83% vs 15%, p < 0.0001) and use of intravenous and/or oral antiplatelet therapy (abciximab, ticlopidine) (64% vs 4%, p < 0.0001) was higher in 1998. Similar angiographic success was achieved in each group with low complication rates. Mean hospital stay was reduced in the 1998 group (2.6 +/- 2.8 vs 4.3 +/- 3.8 days, p < 0.001). Repeat PCI was required more frequently in the 1994 population (26% vs 9%, p < 0.001). Overall there was no significant difference in the mean equipment cost between the two groups ( pound 1551 vs pound 1422, p=ns). CONCLUSION: Despite the widespread use of coronary stenting and antiplatelet therapies there appears to be no difference in current in-hospital equipment costs for PCI compared to 1994. Improved clinical outcomes in the 1998 population imply that stenting is a cost-effective therapy.

Journal Article↗
PubMed2000

Significance of commissural calcification on outcome of mitral balloon valvotomy.

OBJECTIVE: To evaluate the significance of commissural calcification, identified by transthoracic echocardiography, on the haemodynamic and symptomatic outcome of mitral balloon valvotomy. METHODS: Commissural calcification was graded from 0-4 using parasternal short axis transthoracic views. The morphology of the mitral valve was also assessed using the Massachusetts General Hospital echo score. SETTING: A tertiary cardiac centre in Scotland. PATIENTS: 300 patients were studied, 85 retrospectively and 215 prospectively. Mean (SD) age was 59.8 (12.7) years, range 13 to 87; 30% had been judged unsuitable for surgery. Median echo score was 6.8 (3.0), range 2-16. MAIN OUTCOME MEASURES: Immediate increase in mitral valve area and in New York Heart Association functional class 1-3 months after balloon valvotomy. RESULTS: On univariate and multivariate analysis, commissural calcification grade was a significant predictor of achieving a mitral valve area of > 1.50 cm(2) without severe mitral reflux. Its influence was greatest in patients with an echo score </= 8: those with commissural calcification grade 0/1 had significantly greater improvement in valve area and symptom status than those with grade 2/3; the proportions of patients achieving a final valve area of > 1.50 cm(2) were 67% and 46%, respectively (p < 0.05). In patients with an echo score of > 8, the influence of commissural calcification was smaller and not significant. CONCLUSIONS: Commissural calcification as assessed by transthoracic echocardiography is a useful predictor of outcome in patients with otherwise "good" valves (echo score </= 8). Calcification of one commissure or more predicts a less than 50% probability of achieving a valve area above 1.50 cm(2) and is an indication for valve replacement in those who are suitable for surgery.

Adolescent↗
PubMed1999

Comparison of the short-term effects of candoxatril, an orally active neutral endopeptidase inhibitor, and frusemide in the treatment of patients with chronic heart failure.

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.

Atrial Natriuretic Factor↗
PubMed1999

Placebo-controlled comparison of candoxatril, an orally active neutral endopeptidase inhibitor, and captopril in patients with chronic heart failure.

AIMS: 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. METHODS: In this multi-centre double-blind placebo controlled study, 60 patients with NYHA Class I-III heart failure were randomised to candoxatril 200 mg b.d. (n = 22), captopril 25-50 mg b.d. (n = 23) or placebo (n = 15). Treadmill exercise tests were carried out weekly during a 5-week single-blind placebo run-in phase until a stable baseline was achieved, and repeated at 4 weekly intervals during the 12-week double-blind treatment phase. RESULTS: Nine patients withdrew from the study--four candoxatril and five captopril. The placebo-adjusted increase in exercise duration after 12 weeks was 56 s (95% CI, -26 to +137 s; P = 0.12) with candoxatril and 37 s (-43 to + 117 s; P = 0.29) with captopril. CONCLUSIONS: Both candoxatril and captopril were well tolerated and treadmill exercise duration appeared to increase during 12 weeks of therapy but this did not achieve statistical significance. This study tentatively suggests that in patients with heart failure, neutral endopeptidase inhibition may provide similar symptomatic benefits to angiotensin converting enzyme inhibition.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Candoxatril improves exercise capacity in patients with chronic heart failure receiving angiotensin converting enzyme inhibition.

AIMS: To assess the effect of candoxatril, a novel neutral endopeptidase inhibitor, on exercise capacity, clinical status and quality of life in patients with mild to moderate chronic heart failure receiving angiotensin converting enzyme inhibition. METHODS AND RESULTS: Patients were recruited from 16 centres throughout the United Kingdom. Following a 4-week single-blind placebo 'run-in' phase of weekly exercise tests, patients underwent double-blind randomization to receive either candoxatril (100 mg twice daily) or placebo for the next 84 days. Patients were then reassessed every 28 days. Of 110 patients randomized, 56 received candoxatril and 54 placebo. Over the study period, the overall improvement in mean total exercise time in the candoxatril group in comparison to the placebo group was 34.1 s (P=0.02: 95% confidence interval: 5.1 to 63.0). There were no significant changes in functional class, clinical status or quality of life scores between the two groups. There was a trend for a small reduction in blood pressure in the candoxatril group. CONCLUSION: Candoxatril confers an improvement in exercise capacity in patients with chronic heart failure who are receiving maintenance angiotensin converting enzyme inhibitor therapy.

Aged↗
PubMed1995

Perfusion/ventilation mismatch during exercise in chronic heart failure: an investigation of circulatory determinants.

BACKGROUND: The ventilatory cost of carbon dioxide (CO2) elimination on exercise (VE/VCO2) is increased in chronic heart failure (CHF). This reflects increased physiological dead space ventilation secondary to mismatching between perfusion and ventilation during exercise. The objectives of this study were to investigate the relation of this increased VE/VCO2 slope to the syndrome of CHF or to limitation of the exercise related increase of pulmonary blood flow, or both. PATIENTS AND METHODS: Maximal treadmill exercise tests with respiratory gas analysis were performed in 45 patients with CHF (defined as resting left ventricular ejection fraction < 40% on radionuclide scan); 15 normal controls; 23 patients with coronary artery disease and normal resting left ventricular function; and 13 pacemaker dependent patients (six with and seven without CHF) directly comparing exercise responses in rate responsive and fixed rate mode. RESULTS: Patients with CHF had a steeper VE/VCO2 slope than normal controls: this was related inversely to peak VO2 below 20 mol/min/kg. In patients with coronary artery disease in whom peak VO2 (at respiratory exchange ratio > 1) was as limited as in the patients with CHF but resting left ventricular function was normal, the VE/VCO2 slope was normal. In pacemaker dependent patients fixed rate pacing resulted in lower exercise capacity and peak VO2 than rate responsive pacing; the VE/VCO2 slope was normal in patients without CHF but steeper than normal in patients with CHF; the VE/VCO2 slope was steeper during fixed rate than during rate responsive pacing in these patients with CHF. CONCLUSIONS: These findings suggest that the perfusion/ventilation mismatch during exercise in CHF is related to the chronic consequences of the syndrome and not directly to limitation of exercise related pulmonary flow. Only when the syndrome of CHF is present can matching between perfusion and ventilation be acutely influenced by changes in pulmonary flow.

Adult↗
PubMed1995

Severe coronary vasospasm associated with hyperthyroidism causing myocardial infarction.

A 48 year old woman presented with angina after an anterior myocardial infarction and was found to be hyperthyroid. Coronary angiography showed a stenosis of the left coronary os and a long, severe stenosis of the left anterior descending artery which was partially relieved by glyceryl trinitrate. Three months later, after radioactive iodine treatment had rendered her euthyroid, repeat coronary angiography showed entirely normal coronary arteries. This unusual case establishes an association between hyperthyroidism and coronary vasospasm resulting in myocardial infarction.

Acute Disease↗