Publications
712 results found
Colhoun HM, Francis DP, Rubens MB, et al., 2001, The association of heart-rate variability with cardiovascular risk factors and coronary artery calcification - A study in type 1 diabetic patients and the general population, DIABETES CARE, Vol: 24, Pages: 1108-1114, ISSN: 0149-5992
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- Citations: 75
Schmidt HB, Rauchhaus M, Francis DP, et al., 2001, Assessment of chemoreflex sensitivity in free breathing young subjects by correction for respiratory influence., Int J Cardiol, Vol: 78, Pages: 157-165, ISSN: 0167-5273
BACKGROUND: The assessment of autonomic function is an important tool for risk stratification in critically ill patients. Peripheral cardiac chemoreflex sensitivity has been considered a marker for increased risk of sudden cardiac death. In normals, the evaluation of peripheral cardiac chemoreflex sensitivity is performed under controlled breathing conditions during inhalation of hypoxic gas. Since this is poorly tolerated by patients, they are commonly studied under hyperoxic conditions, which are not physiological. METHODS: We studied 20 healthy volunteers who underwent free and controlled breathing of a hypoxic gas mixture (10% O2 in N2) over 5 min. Values of peripheral cardiac chemoreflex sensitivity, corrected for respiratory influence, were compared with the results obtained experimentally under controlled breathing conditions in the same subjects. RESULTS: We found a substantial difference between values obtained during free and controlled breathing (3.64 +/- 0.81 vs. 1.53 +/- 0.32 ms/mmHg, respectively; P < 0.05). After application of a respiratory correction, described and validated in this article, no significant difference was seen for these values (0.89 +/-0.91 vs. 1.53 +/- 0.32 ms/mmHg, P = 0.46). CONCLUSIONS: This approach allows the evaluation of peripheral cardiac chemoreflex sensitivity in free breathing subjects. This correction could improve the assessment of cardiac chemoreflex sensitivity in patients with cardiorespiratory disorders, who find it difficult to control their breathing according to an experimental protocol.
Davies LC, Francis DP, Ponikowski P, et al., 2001, Relation of heart rate and blood pressure turbulence following premature ventricular complexes to baroreflex sensitivity in chronic congestive heart failure, AMERICAN JOURNAL OF CARDIOLOGY, Vol: 87, Pages: 737-742, ISSN: 0002-9149
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- Citations: 114
Ponikowski P, Francis DP, Piepoli MF, et al., 2001, Enhanced ventilatory response to exercise in patients with chronic heart failure and preserved exercise tolerance - Marker of abnormal cardiorespiratory reflex control and predictor of poor prognosis, CIRCULATION, Vol: 103, Pages: 967-972, ISSN: 0009-7322
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- Citations: 320
Francis D, 2001, The 50th annual scientific session of the American College of Cardiology. Orlando, FL, USA, March 18-21, 2001., Heart Fail Monit, Vol: 1, Pages: 150-152, ISSN: 1470-8590
Rauchhaus M, Doehner W, Francis DP, et al., 2000, Plasma cytokine parameters and mortality in patients with chronic heart failure, CIRCULATION, Vol: 102, Pages: 3060-3067, ISSN: 0009-7322
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- Citations: 668
Scott AC, Francis DP, Davies LC, et al., 2000, Contribution of skeletal muscle 'ergoreceptors' in the human leg to respiratory control in chronic heart failure, JOURNAL OF PHYSIOLOGY-LONDON, Vol: 529, Pages: 863-870, ISSN: 0022-3751
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- Citations: 73
Rauchhaus M, Koloczek V, Volk HD, et al., 2000, Inflammatory cytokines and the possible immunological role for lipoproteins in chronic heart failure, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 76, Pages: 125-133, ISSN: 0167-5273
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- Citations: 115
Davies LC, Francis DP, Crisafulli A, et al., 2000, Oscillations in stroke volume and cardiac output arising from oscillatory ventilation in humans, EXPERIMENTAL PHYSIOLOGY, Vol: 85, Pages: 857-862, ISSN: 0958-0670
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- Citations: 11
Francis DP, Willson K, Davies LC, et al., 2000, Quantitative general theory for periodic breathing in chronic heart failure and its clinical implications, CIRCULATION, Vol: 102, Pages: 2214-2221, ISSN: 0009-7322
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- Citations: 157
Ponikowski PP, Chua TP, Davies CL, et al., 2000, Central chemoreflex overactivity interacts with ergoreflex in the ventilatory response to exercise in chronic heart failure patients., CIRCULATION, Vol: 102, Pages: 221-221, ISSN: 0009-7322
Chambers JS, Francis DP, Coats AJS, 2000, Recovery oxygen uptake and brain natriuretic peptide as markers of exercise capacity in chronic heart failure, ISSN: 0264-0414
Chambers JS, Francis DP, Marinho DJM, et al., 2000, Pulmonary function, resting respiratory muscle strength and cardiopulmonary exercise capacity in chronic heart failure patients, Pages: 509-510, ISSN: 0264-0414
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- Citations: 1
Francis DP, Davies LC, Willson K, et al., 2000, Very-low-frequency oscillations in heart rate and blood pressure in periodic breathing: role of the cardiovascular limb of the hypoxic chemoreflex, CLINICAL SCIENCE, Vol: 99, Pages: 125-132, ISSN: 0143-5221
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- Citations: 24
Florea VG, Henein MY, Cicoira M, et al., 2000, Echocardiographic determinants of mortality in patients >67 years of age with chronic heart failure, AMERICAN JOURNAL OF CARDIOLOGY, Vol: 86, Pages: 158-161, ISSN: 0002-9149
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- Citations: 17
Francis DP, Willson K, Ceri Davies L, et al., 2000, True shape and area of proximal isovelocity surface area (PISA) when flow convergence is hemispherical in valvular regurgitation., Int J Cardiol, Vol: 73, Pages: 237-242, ISSN: 0167-5273
The proximal isovelocity surface area (PISA) method for quantifying valvular regurgitation uses an echocardiographic image with superimposed colour Doppler mapping to visualise the contours of velocity in the blood travelling towards the regurgitant orifice. The flux of blood through the regurgitant orifice is obtained as the product of the area of one of these (presumed hemispherical) contours and the speed of the blood passing through it. However, colour Doppler mapping measures the velocity component towards the echo probe (v cos theta;) rather than speed (v), so that the contours of equal Doppler velocity (isodoppler velocity contours) differ from isospeed contours. We derive the shape of the isodoppler contour surface obtainable by colour Doppler mapping, and show that its area is much less than that of the hemispherical isospeed contour. When regurgitant flux is derived from an appropriate single measure of contour dimension, an appropriate result may be obtained. However, if the true echocardiographic surface area is measured directly, the regurgitant flux will be substantially underestimated. Indeed, the conditions necessary for isodoppler velocity contours to be hemispherical are extraordinary. We should not therefore make deductions from the apparent shape for the convergence zone without considering the principles by which the image is generated. The discrepancy will assume practical significance when increased resolution of colour Doppler technology makes measurement of apparent surface area feasible. Assuming the flow contours are indeed hemispherical, a 'correction' factor of 1.45 would be required.
Francis DP, Davies LC, Willson K, et al., 2000, Analytical identification of ideal pulmonary-systemic flow balance in patients with a cavopulmonary shunt in hypoplastic left heart syndrome: oxygen delivery or tissue oxygenation?, EUROPEAN HEART JOURNAL, Vol: 21, Pages: 434-434, ISSN: 0195-668X
Francis DP, Willson K, Davies LC, et al., 2000, Quantitative general theory for periodic breathing in chronic heart failure and its clinical implications, Heart, Vol: 83, ISSN: 1355-6037
Background: Periodic breathing (PB) in chronic heart failure (CHF) carries a poor prognosis. Although studies have identified clinical associations, there is no simple general theory which quantitatively explains PB and the mechanisms of its treatment, using widely-understood clinical concepts. We introduce a new approach to the quantitative analysis of these dynamics. Method and Results: A theoretical algebraic formula is derived and presented as a simple plot enabling prediction, from easily-acquired clinical data, of whether cardiorespiratory control will be stable or will oscillate (PB). A clinical validation study was carried out in 10 CHF patients with PB, 10 CHF patients without PB, and 10 healthy normals. Chemoreflex sensitivity (S) its delay time (δ), effective alveolar volume (VL), and mean end-tidal CO2 fraction (C) were combined according to the algebraic formula: the pattern of breathing was correctly predicted in 28/30 subjects. The principal combined parameter (C S δ/VL) was higher in patients with PB (mean 14.2 [SE 3.0]) than in those without PB (3.1 [0.5], p=0.0005) or normal controls (2.4 [0.5], p=0.0003). This was due to differences in both chemoreflex sensitivity (1749 [235] vs 620 [103] and 526 [104] l/min/atmCO2, p=0.0001 and p<0.0001 respectively) and chemoreflex delay (0.53 [0.06] vs 0.40 [0.06] and 0.30 [0.04] min, p=NS and p=0.02 respectively). Conclusion: This analysis defines the origin of PB explicitly, and has implications for rational therapy. The clinical data emphasises the role of the pathophysiology of PB for both chemoreflex gain and delay time. (Graph Presented).
Florea VG, Henein MY, Anker SD, et al., 2000, Relation of changes over time in ventricular size and function to those in exercise capacity in patients with chronic heart failure, AMERICAN HEART JOURNAL, Vol: 139, Pages: 913-917, ISSN: 0002-8703
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- Citations: 11
Francis DP, Davies LC, Coats AJ, 2000, Qualification of the concepts of unqualified success and unmitigated failure., Circulation, Vol: 101
Clark AL, Davies LC, Francis DP, et al., 2000, Ventilatory capacity and exercise tolerance in patients with chronic stable heart failure, EUROPEAN JOURNAL OF HEART FAILURE, Vol: 2, Pages: 47-51, ISSN: 1388-9842
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- Citations: 17
Davies LC, Francis DP, Piepoli M, et al., 2000, Chronic heart failure in the elderly: value of cardiopulmonary exercise testing in risk stratification, HEART, Vol: 83, Pages: 147-151, ISSN: 1355-6037
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- Citations: 50
Davies LC, Francis DP, Piepoli M, et al., 2000, Chronic heart failure in the elderly: The value of cardiopulmonary exercise testing in risk stratification, JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, Vol: 35, Pages: 220A-220A, ISSN: 0735-1097
Francis DP, 2000, Shuttle versus six-minute walk test in the prediction of outcome in chronic heart failure - Editorial comment, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 76, Pages: 105-106, ISSN: 0167-5273
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- Citations: 4
Francis DP, Coats AJS, Ponikowski P, 2000, Chemoreflex-Baroreflex Interactions in Cardiovascular Disease, Sleep Apnea: Implications in Cardiovascular and Cerebrovascular Disease: Volume 146, Pages: 33-60, ISBN: 9781498743341
Reflex feedback control mechanisms play important roles in the maintenance of homeostasis in many physiological systems. Physiologists have over the past few decades have acquired detailed information on the behavior of such re?exes in intact physiological states in regulating the cardiovascular and respiratory systems. In this chapter we survey these ?ndings, and then address the state of knowledge of the interplay between these regulatory re?exes in health and in the presence of chronic heart failure.
Florea VG, Henein MY, Anker SD, et al., 2000, Prognostic value of changes over time in exercise capacity and echocardiographic measurements in patients with chronic heart failure, EUROPEAN HEART JOURNAL, Vol: 21, Pages: 146-153, ISSN: 0195-668X
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- Citations: 60
Francis DP, Shamim W, Davies LC, et al., 2000, Cardiopulmonary exercise testing for prognosis in chronic heart failure:: continuous and independent prognostic value from VE/VCO<sub>2</sub> slope and peak VO<sub>2</sub>, EUROPEAN HEART JOURNAL, Vol: 21, Pages: 154-161, ISSN: 0195-668X
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- Citations: 381
Francis D, Davies C, 2000, 49th Annual Scientific Sessions of the American College of Cardiology., Heart Fail Monit, Vol: 1, Pages: 37-39, ISSN: 1470-8590
Francis DP, Davies LC, Coats AJ, 1999, Pulmonary clearance of endothelin-1 on heart failure: reduced or normal?, Circulation, Vol: 100
Francis DP, Davies LC, Coats AJS, 1999, Pulmonary clearance of endothelin-1 on heart failure: Reduced or normal?, CIRCULATION, Vol: 100, Pages: E135-E135, ISSN: 0009-7322
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