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183 results on '"Paton, J. F. R."'

17. Renal Denervation Update From the International Sympathetic Nervous System Summit:JACC State-of-the-Art Review

Author

Kiuchi M. G., Esler M. D., Fink G. D., Osborn J. W., Banek C. T., Bohm M., Denton K. M., DiBona G. F., Everett T. H., Grassi G., Katholi R. E., Knuepfer M. M., Kopp U. C., Lefer D. J., Lohmeier T. E., May C. N., Mahfoud F., Paton J. F. R., Schmieder R. E., Pellegrino P. R., Sharabi Y., Schlaich M. P., Kiuchi, M, Esler, M, Fink, G, Osborn, J, Banek, C, Bohm, M, Denton, K, Dibona, G, Everett, T, Grassi, G, Katholi, R, Knuepfer, M, Kopp, U, Lefer, D, Lohmeier, T, May, C, Mahfoud, F, Paton, J, Schmieder, R, Pellegrino, P, Sharabi, Y, and Schlaich, M

Subjects
sympathetic nervous system, hypertension, cardiovascular disease, blood pressure, renal denervation
Abstract

Three recent renal denervation studies in both drug-naïve and drug-treated hypertensive patients demonstrated a significant reduction of ambulatory blood pressure compared with respective sham control groups. Improved trial design, selection of relevant patient cohorts, and optimized interventional procedures have likely contributed to these positive findings. However, substantial variability in the blood pressure response to renal denervation can still be observed and remains a challenging and important problem. The International Sympathetic Nervous System Summit was convened to bring together experts in both experimental and clinical medicine to discuss the current evidence base, novel developments in our understanding of neural interplay, procedural aspects, monitoring of technical success, and others. Identification of relevant trends in the field and initiation of tailored and combined experimental and clinical research efforts will help to address remaining questions and provide much-needed evidence to guide clinical use of renal denervation for hypertension treatment and other potential indications.

Published
2019

24. Quantifying sympathetic neuro-haemodynamic transduction at rest in humans:Insights into sex, ageing and blood pressure control

Author

Briant, L J B, Burchell, A E, Ratcliffe, L E K, Charkoudian, N, Nightingale, A K, Paton, J F R, Joyner, Michael J, and Hart, E C

Subjects
Bristol Heart Institute, CRICBristol
Abstract

Sex and age differences in the sympathetic control of resting blood pressure (BP) may be due to differences in the transduction of sympathetic nerve activity (SNA) into vascular tone. Current methods for dynamically quantifying transduction focus on the relationship between SNA and vasoconstriction during a pressor stimulus, which increases BP and may be contra-indicated in patients. We describe a simple analytical method for quantifying transduction under resting conditions. We performed linear regression analysis of binned muscle SNA burst areas against diastolic BP (DBP). We assessed whether the slope of this relationship reflects the transduction of SNA into DBP. To evaluate this, we investigated whether this measure captures differences in transduction in different populations. Specifically, we (1) quantified transduction in young men (YM), young women (YW), older men (OM) and postmenopausal women (PMW); and (2) measured changes in transduction during β-blockade using propranolol in YW, YM and PMW. YM had a greater transduction vs. OM (0.10 ± 0.01mmHg/ %·s, n = 23vs. 0.06 ± 0.01mmHg/ %·s, n = 18; P = 0.003). Transduction was lowest in YW (0.02 ± 0.01 mmHg/%·s, n = 23) and increased during β-blockade (0.11 ± 0.01 mmHg/%·s; P < 0.001). Transduction in PMW (0.07 ± 0.01 mmHg/%·s, n = 23) was greater compared to YW (P = 0.001), and was not altered during β-blockade (0.06 ± 0.01 mmHg/%·s; P = 0.98). Importantly, transduction increased in women with age, but decreased in men. Transduction in women intersected that in men at 55 ± 1.5 years. This measure of transduction captures age- and sex-differences in the sympathetic regulation of DBP and may be valuable in quantifying transduction in disease. In particular, this measure may help target treatment strategies in specific hypertensive sub-populations.

Published
2016

26. Brain stem P[O.sub.2] and pH of the working heart-brain stem preparation during vascular perfusion with aqueous medium

Author

WILSON, R. J. A., REMMERS, J. E., and PATON, J. F. R.

Subjects
Perfusion (Physiology) -- Research, Cardiovascular research -- Analysis, Respiration -- Physiological aspects, Biological sciences
Abstract

The rat working heart-brain stem preparation (WHBP) is an in situ preparation having many of the advantages associated with in vitro preparations while retaining cardiovascular response functionality and an eupnoeic respiratory motor pattern. The preparation is perfused arterially with an aqueous medium having a much lower oxygen-carrying capacity than blood. To evaluate the efficacy of the artificial perfusion in providing adequate gas exchange within the brain stem, we used polarographic P[O.sub.2] and pH microelectrodes to determine the tissue P[O.sub.2] and pH of the medulla oblongata at various depths. When the perfusate was equilibrated with 5% [CO.sub.2] and 95% [O.sub.2], average tissue P[O.sub.2] was 294 Torr and no hypoxic areas were encountered. Tissue pH was remarkably uniform throughout the tissue, and on average was only 0.04 [+ or -] 0.02 pH units more acidic than that of the perfusate. Increasing the P[CO.sub.2] of the perfusate increased tissue P[O.sub.2] and decreased arterial resistance. Decreasing perfusate P[CO.sub.2] (while keeping pH constant) decreased tissue P[O.sub.2] and reduced the respiratory activity. These results suggest that arterial P[CO.sub.2], independent of arterial pH, is an essential variable in determining both respiratory drive and cerebrovascular perfusion. We conclude that the medulla of the WHBP is oxygenated and within a physiological pH, which accounts for the eupneic pattern of respiratory motor activity it generates. Furthermore, this preparation may be a useful model for exploring mechanisms of central chemoreception as well as the dynamics of the cerebral vasculature responses following changes in blood gases. cardiovascular; respiration; breathing; eupnea

Published
2001

29. The effect of obesity on electrocardiographic detection of hypertensive left ventricular hypertrophy: recalibration against cardiac magnetic resonance

Author

Rodrigues, J C L, primary, McIntyre, B, additional, Dastidar, A G, additional, Lyen, S M, additional, Ratcliffe, L E, additional, Burchell, A E, additional, Hart, E C, additional, Bucciarelli-Ducci, C, additional, Hamilton, M C K, additional, Paton, J F R, additional, Nightingale, A K, additional, and Manghat, N E, additional

Published
2015
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49. The effect of obesity on electrocardiographic detection of hypertensive left ventricular hypertrophy: recalibration against cardiac magnetic resonance

Author

Rodrigues, J C L, McIntyre, B, Dastidar, A G, Lyen, S M, Ratcliffe, L E, Burchell, A E, Hart, E C, Bucciarelli-Ducci, C, Hamilton, M C K, Paton, J F R, Nightingale, A K, and Manghat, N E

Abstract

Electrocardiograph (ECG) criteria for left ventricular hypertrophy (LVH) are a widely used clinical tool. We recalibrated six ECG criteria for LVH against gold-standard cardiac magnetic resonance (CMR) and assessed the impact of obesity. One hundred and fifty consecutive tertiary hypertension clinic referrals for CMR (1.5 T) were reviewed. Patients with cardiac pathology potentially confounding hypertensive LVH were excluded (n=22). The final sample size was 128 (age: 51.0±15.2 years, 48% male). LVH was defined by CMR. From a 12-lead ECG, Sokolow–Lyon voltage and product, Cornell voltage and product, Gubner–Ungerleidger voltage and Romhilt–Estes score were evaluated, blinded to the CMR. ECG diagnostic performance was calculated. LVH by CMR was present in 37% and obesity in 51%. Obesity significantly reduced ECG sensitivity, because of significant attenuation in mean ECG values for Cornell voltage (22.2±5.7 vs 26.4±9.4 mm, P<0.05), Cornell product (2540±942 vs 3023±1185 mm • ms, P<0.05) and for Gubner–Ungerleider voltage (18.2±7.1 vs 23.3±1.2 mm, P<0.05). Obesity also significantly reduced ECG specificity, because of significantly higher prevalence of LV remodeling (no LVH but increased mass-to-volume ratio) in obese subjects without LVH (36% vs 16%, P<0.05), which correlated with higher mean ECG LVH criteria values. Obesity-specific partition values were generated at fixed 95% specificity; Cornell voltage had highest sensitivity in non-obese (56%) and Sokolow–Lyon product in obese patients (24%). Obesity significantly lowers ECG sensitivity at detecting LVH, by attenuating ECG LVH values, and lowers ECG specificity through changes associated with LV remodeling. Our obesity-specific ECG partition values could improve the diagnostic performance in obese patients with hypertension.

Published
2016
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