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Hauser JA, Jones A, Pandya B, Taylor AM, Muthurangu V. Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology. Am J Physiol Heart Circ Physiol 2020; 319:H808-H813. [PMID: 32857602 PMCID: PMC7654659 DOI: 10.1152/ajpheart.00500.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 07/23/2020] [Accepted: 08/25/2020] [Indexed: 11/22/2022]
Abstract
In univentricular (Fontan) physiology, peripheral and splanchnic vascular tone may be raised to counteract reduced cardiac output (CO) and elevated central venous pressure and thus maintain vital organ perfusion. This could negatively affect the normal cardiovascular response to food ingestion, where mesenteric vasodilation and a concurrent rise in CO are central. We sought to elucidate this using rapid cardiovascular MRI. Thirty fasting subjects (50% controls, 40% women and 60% men) ingested a standardized meal. Responses over ~50 min in mean arterial pressure (MAP), CO, and blood flow in all major aortic branches were measured, and regional vascular impedance (Z0) was calculated. Differences from baseline and between groups were assessed by repeated-measures mixed models. Compared with the control group, the Fontan patient group had greater fasting Z0 of the legs and kidneys, resulting in greater systemic Z0 and similar MAP. They further had similar blood flow to the digestive organs at baseline, despite larger variation in mesenteric resistance. Postprandially, blood flow to the legs decreased in the control group but not in the Fontan patient group. Increases in CO and superior mesenteric blood flow were similar in both groups, but the celiac response was blunted in the Fontan patient group. No significant differences in MAP responses were observed. In conclusion, alterations in vascular tone to counteract adverse hemodynamics and raised hepatic afterload may blunt vasoreactivity in the legs and the celiac axis in Fontan physiology. Further study is needed to determine whether blunted celiac or mesenteric vasoreactivity is linked to deteriorating hemodynamics and poor prognosis in Fontan patients.NEW & NOTEWORTHY Novel data on cardiovascular physiology in response to a meal in Fontan patients are presented. Using a previously validated dynamic MRI protocol, we demonstrated that the usual increase in cardiac output and the dilation of the superior mesenteric artery are preserved in clinically well Fontan patients. In contrast, vasoconstriction of the legs may have prevented redistribution of blood flow from this region in response to the meal. This may also affect responses to other types of stress. Celiac vasodilation was also absent in Fontan patients. This may be due to abnormal hepatic circulation. The proposed protocol may be used to study Fontan complications secondary to abnormal regional hemodynamics.
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Affiliation(s)
- Jakob A Hauser
- Centre for Translational Cardiovascular Imaging, University College London, London, United Kingdom
- Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Alexander Jones
- Centre for Translational Cardiovascular Imaging, University College London, London, United Kingdom
- Department of Pediatrics, University of Oxford, Oxford, United Kingdom
| | | | - Andrew M Taylor
- Centre for Translational Cardiovascular Imaging, University College London, London, United Kingdom
- Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Vivek Muthurangu
- Centre for Translational Cardiovascular Imaging, University College London, London, United Kingdom
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Hauser JA, Muthurangu V, Sattar N, Taylor AM, Jones A. Postprandial Vascular Dysfunction Is Associated With Raised Blood Pressure and Adverse Left Ventricular Remodeling in Adolescent Adiposity. Circ Cardiovasc Imaging 2019; 12:e009172. [PMID: 31707792 DOI: 10.1161/circimaging.119.009172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular disease, including heart failure. Although linked to obesity and hypertension, its pathogenesis is multifactorial. Blunted postprandial sympathetic regulation of gut blood flow has been observed in overweight animals and suggested as a promotor of hypertension and LVH. We hypothesized that blunted postprandial superior mesenteric blood flow responses would be more common in overweight humans and associated with increased blood pressure and LVH. METHODS Left ventricular dimensions and hemodynamic responses to a standardized high-calorie liquid meal were measured in healthy adolescents (n=82; 39 overweight/obese) by magnetic resonance imaging. Covariates such as body mass index, blood pressure, Tanner score, and an index of insulin resistance were included in multiple regression models to examine the independent associations of mesenteric flow response with blood pressure status and LVH. RESULTS Food ingestion increased cardiac output (Δmean, 0.45 [SD, 0.62] L·min-1; P=3.8×10-8) and superior mesenteric artery flow (Δmean, 0.76 [SD, 0.35] L·min-1; P=4.2×10-31). A blunted mesenteric flow response was associated with increased left ventricular mass (B=-12.7 g·m-2.7 per L·min-1·m-0.92; P=6×10-5) and concentric LVH (log likelihood, -9.9; P=0.001), independently of known determinants of LVH, including body mass index. It was also associated with elevated systolic blood pressure (B=-18.0 mm Hg per L·min-1·m-0.92; P=0.001), but this link did not explain the association with left ventricular mass. CONCLUSIONS Postprandial mesenteric vascular dysfunction is associated with LVH and hypertension, independently of common risk factors for those conditions. These findings highlight a new, independent marker of cardiovascular risk in the young.
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Affiliation(s)
- Jakob A Hauser
- Centre for Cardiovascular Imaging, University College London, United Kingdom (J.A.H., V.M., A.M.T.)
- Department of Paediatrics and Adolescent Medicine, Division of Paediatric Cardiology, Medical University of Vienna, Austria (J.A.H.)
| | - Vivek Muthurangu
- Centre for Cardiovascular Imaging, University College London, United Kingdom (J.A.H., V.M., A.M.T.)
| | - Naveed Sattar
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, United Kingdom (N.S.)
| | - Andrew M Taylor
- Centre for Cardiovascular Imaging, University College London, United Kingdom (J.A.H., V.M., A.M.T.)
| | - Alexander Jones
- Department of Paediatrics, University of Oxford, United Kingdom (A.J.)
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Phase-contrast magnetic resonance imaging to assess renal perfusion: a systematic review and statement paper. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2019; 33:3-21. [PMID: 31422518 PMCID: PMC7210220 DOI: 10.1007/s10334-019-00772-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/09/2019] [Accepted: 08/01/2019] [Indexed: 02/07/2023]
Abstract
Objective Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive method used to compute blood flow velocity and volume. This systematic review aims to discuss the current status of renal PC-MRI and provide practical recommendations which could inform future clinical studies and its adoption in clinical practice. Methodology A comprehensive search of all the PC-MRI studies in human healthy subjects or patients related to the kidneys was performed. Results A total of 39 studies were included in which PC-MRI was used to measure renal blood flow (RBF) alongside other derivative hemodynamic parameters. PC-MRI generally showed good correlation with gold standard methods of RBF measurement, both in vitro and in vivo, and good reproducibility. Despite PC-MRI not being routinely used in clinical practice, there are several clinical studies showing its potential to support diagnosis and monitoring of renal diseases, in particular renovascular disease, chronic kidney disease and autosomal dominant polycystic kidney disease. Discussion Renal PC-MRI shows promise as a non-invasive technique to reliably measure RBF, both in healthy volunteers and in patients with renal disease. Future multicentric studies are needed to provide definitive normative ranges and to demonstrate the clinical potential of PC-MRI, likely as part of a multi-parametric renal MRI protocol. Electronic supplementary material The online version of this article (10.1007/s10334-019-00772-0) contains supplementary material, which is available to authorized users.
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Cox EF, Buchanan CE, Bradley CR, Prestwich B, Mahmoud H, Taal M, Selby NM, Francis ST. Multiparametric Renal Magnetic Resonance Imaging: Validation, Interventions, and Alterations in Chronic Kidney Disease. Front Physiol 2017; 8:696. [PMID: 28959212 PMCID: PMC5603702 DOI: 10.3389/fphys.2017.00696] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 08/30/2017] [Indexed: 12/15/2022] Open
Abstract
Background: This paper outlines a multiparametric renal MRI acquisition and analysis protocol to allow non-invasive assessment of hemodynamics (renal artery blood flow and perfusion), oxygenation (BOLD T2*), and microstructure (diffusion, T1 mapping). Methods: We use our multiparametric renal MRI protocol to provide (1) a comprehensive set of MRI parameters [renal artery and vein blood flow, perfusion, T1, T2*, diffusion (ADC, D, D*, fp), and total kidney volume] in a large cohort of healthy participants (127 participants with mean age of 41 ± 19 years) and show the MR field strength (1.5 T vs. 3 T) dependence of T1 and T2* relaxation times; (2) the repeatability of multiparametric MRI measures in 11 healthy participants; (3) changes in MRI measures in response to hypercapnic and hyperoxic modulations in six healthy participants; and (4) pilot data showing the application of the multiparametric protocol in 11 patients with Chronic Kidney Disease (CKD). Results: Baseline measures were in-line with literature values, and as expected, T1-values were longer at 3 T compared with 1.5 T, with increased T1 corticomedullary differentiation at 3 T. Conversely, T2* was longer at 1.5 T. Inter-scan coefficients of variation (CoVs) of T1 mapping and ADC were very good at <2.9%. Intra class correlations (ICCs) were high for cortex perfusion (0.801), cortex and medulla T1 (0.848 and 0.997 using SE-EPI), and renal artery flow (0.844). In response to hypercapnia, a decrease in cortex T2* was observed, whilst no significant effect of hyperoxia on T2* was found. In CKD patients, renal artery and vein blood flow, and renal perfusion was lower than for healthy participants. Renal cortex and medulla T1 was significantly higher in CKD patients compared to healthy participants, with corticomedullary T1 differentiation reduced in CKD patients compared to healthy participants. No significant difference was found in renal T2*. Conclusions: Multiparametric MRI is a powerful technique for the assessment of changes in structure, hemodynamics, and oxygenation in a single scan session. This protocol provides the potential to assess the pathophysiological mechanisms in various etiologies of renal disease, and to assess the efficacy of drug treatments.
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Affiliation(s)
- Eleanor F Cox
- Sir Peter Mansfield Imaging Centre, University of NottinghamNottingham, United Kingdom
| | - Charlotte E Buchanan
- Sir Peter Mansfield Imaging Centre, University of NottinghamNottingham, United Kingdom
| | - Christopher R Bradley
- Sir Peter Mansfield Imaging Centre, University of NottinghamNottingham, United Kingdom
| | - Benjamin Prestwich
- Sir Peter Mansfield Imaging Centre, University of NottinghamNottingham, United Kingdom
| | - Huda Mahmoud
- Centre for Kidney Research and Innovation, Royal Derby Hospital, University of NottinghamDerby, United Kingdom
| | - Maarten Taal
- Centre for Kidney Research and Innovation, Royal Derby Hospital, University of NottinghamDerby, United Kingdom
| | - Nicholas M Selby
- Centre for Kidney Research and Innovation, Royal Derby Hospital, University of NottinghamDerby, United Kingdom
| | - Susan T Francis
- Sir Peter Mansfield Imaging Centre, University of NottinghamNottingham, United Kingdom
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Hauser JA, Muthurangu V, Steeden JA, Taylor AM, Jones A. Comprehensive assessment of the global and regional vascular responses to food ingestion in humans using novel rapid MRI. Am J Physiol Regul Integr Comp Physiol 2016; 310:R541-5. [DOI: 10.1152/ajpregu.00454.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/10/2016] [Indexed: 11/22/2022]
Abstract
Ingestion of food is known to increase mesenteric blood flow. It is not clear whether this increased flow demand is compensated by a rise in cardiac output (CO) alone or by redistribution of blood flow from other organs. We used a new comprehensive imaging method to assess the human cardiovascular response to food ingestion. Following a 12-h fast, blood flow in segments of the aorta and in organ-specific arteries, and ventricular volumes were assessed in 20 healthy adults using MRI at rest and following ingestion of a high-energy liquid meal. Systemic vascular resistance (SVR) fell substantially and CO rose significantly. Blood pressure remained stable. These changes were predominantly driven by a rapid fall in mesenteric vascular resistance, resulting in over four times more intestinal blood flow. Renal vascular resistance also declined but less dramatically. No changes in blood flow to the celiac territory, the brain, or the limbs were observed. In conclusion, this is the first study to fully characterize systemic and regional changes in vascular resistance after food ingestion in humans. Our findings show that the postprandial drop in SVR is fully compensated for by increased CO and not by redistribution of blood from other organs. With the exception of a modest increase in renal blood flow, there was no evidence of altered blood flow to nondigestive organs. The proposed oral food challenge protocol can be applied safely in an MRI environment and may be useful for studying the involvement of the gut in systemic or cardiovascular disease.
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Affiliation(s)
- Jakob A. Hauser
- University College London, Institute of Cardiovascular Science, Centre for Cardiovascular Imaging; London, United Kingdom; and
- Great Ormond Street Hospital for Children, Cardiorespiratory Division; London, United Kingdom
| | - Vivek Muthurangu
- University College London, Institute of Cardiovascular Science, Centre for Cardiovascular Imaging; London, United Kingdom; and
- Great Ormond Street Hospital for Children, Cardiorespiratory Division; London, United Kingdom
| | - Jennifer A. Steeden
- University College London, Institute of Cardiovascular Science, Centre for Cardiovascular Imaging; London, United Kingdom; and
- Great Ormond Street Hospital for Children, Cardiorespiratory Division; London, United Kingdom
| | - Andrew M. Taylor
- University College London, Institute of Cardiovascular Science, Centre for Cardiovascular Imaging; London, United Kingdom; and
- Great Ormond Street Hospital for Children, Cardiorespiratory Division; London, United Kingdom
| | - Alexander Jones
- University College London, Institute of Cardiovascular Science, Centre for Cardiovascular Imaging; London, United Kingdom; and
- Great Ormond Street Hospital for Children, Cardiorespiratory Division; London, United Kingdom
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Keegan J, Patel HC, Simpson RM, Mohiaddin RH, Firmin DN. Inter-study reproducibility of interleaved spiral phase velocity mapping of renal artery haemodynamics. J Cardiovasc Magn Reson 2015; 17:8. [PMID: 25648103 PMCID: PMC4316806 DOI: 10.1186/s12968-014-0105-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 12/16/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Qualitative and quantitative assessment of renal blood flow is valuable in the evaluation of patients with renal and renovascular diseases as well as in patients with heart failure. The temporal pattern of renal flow velocity through the cardiac cycle provides important information about renal haemodynamics. High temporal resolution interleaved spiral phase velocity mapping could potentially be used to study temporal patterns of flow and measure resistive and pulsatility indices which are measures of downstream resistance. METHODS A retrospectively gated breath-hold spiral phase velocity mapping sequence (TR 19 ms) was developed at 3 Tesla. Phase velocity maps were acquired in the proximal right and left arteries of 10 healthy subjects in each of two separate scanning sessions. Each acquisition was analysed by two independent observers who calculated the resistive index (RI), the pulsatility index (PI), the mean flow velocity and the renal artery blood flow (RABF). Inter-study and inter-observer reproducibility of each variable was determined as the mean +/- standard deviation of the differences between paired values. The effect of background phase errors on each parameter was investigated. RESULTS RI, PI, mean velocity and RABF per kidney were 0.71+/- 0.06, 1.47 +/- 0.29, 253.5 +/- 65.2 mm/s and 413 +/- 122 ml/min respectively. The inter-study reproducibilities were: RI -0.00 +/- 0.04 , PI -0.03 +/- 0.17, mean velocity -6.7 +/- 31.1 mm/s and RABF per kidney 17.9 +/- 44.8 ml/min. The effect of background phase errors was negligible (<2% for each parameter). CONCLUSIONS High temporal resolution breath-hold spiral phase velocity mapping allows reproducible assessment of renal pulsatility indices and RABF.
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Affiliation(s)
- Jennifer Keegan
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
| | - Hitesh C Patel
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
| | - Robin M Simpson
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Radiological Physics, University of Freiburg, Freiburg, Germany
| | - Raad H Mohiaddin
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />National Heart and Lung Institute, Imperial College London, London, UK
| | - David N Firmin
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />National Heart and Lung Institute, Imperial College London, London, UK
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