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Gafane-Matemane LF, Craig A, Kruger R, Alaofin OS, Ware LJ, Jones ESW, Kengne AP. Hypertension in sub-Saharan Africa: the current profile, recent advances, gaps, and priorities. J Hum Hypertens 2024:10.1038/s41371-024-00913-6. [PMID: 38698111 DOI: 10.1038/s41371-024-00913-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 05/05/2024]
Abstract
Recent global and regional reports consistently confirm the high and increasing prevalence of hypertension in sub-Saharan Africa (SSA), with poor detection, treatment, and control rates. This narrative review summarises the burden of hypertension in SSA and recent findings from community-based hypertension management strategies. We further outline prominent risk factors according to recent data and associated underlying mechanisms for hypertension development. An extensive review of literature showed that most countries have reported on the prevalence of hypertension during 2017-2023, despite limitations linked to the lack of nationally representative studies, heterogeneity of sampling and data collection methods. Task-shifting approaches that assign roles to model patients and community health workers reported improved linkage to healthcare services and adherence to medication, with inconsistent findings on blood pressure (BP)-lowering effects over time. The regularly reported risk factors include unhealthy diet, sedentary lifestyle, increased adiposity and underweight, ageing, level of education, and/or income as well as psychosocial factors. Newer data on the pathophysiological mechanisms leading to hypertension and potential areas of intervention are reported from children and adults and include, among others, salt-handling and volume overload, endothelial function, BP dipping patterns and the role of human immunodeficiency virus . To conclude, significant strides have been made in data reporting from SSA on the burden of hypertension in the region as well as biomarker research to improve understanding and identification of areas of intervention. However, gaps remain on linkage between knowledge generation, translation, and implementation research. Coordinated studies addressing both discovery science and public health are crucial to curb hypertension development and improve management in SSA.
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Affiliation(s)
- Lebo F Gafane-Matemane
- Hypertension in Africa Research Team, North-West University, Potchefstroom, 2520, South Africa.
- SAMRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, 2520, South Africa.
| | - Ashleigh Craig
- SAMRC/Wits Developmental Pathways for Health Research Unit (DPHRU), University of the Witwatersrand, Soweto, 1864, South Africa
| | - Ruan Kruger
- Hypertension in Africa Research Team, North-West University, Potchefstroom, 2520, South Africa
- SAMRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, 2520, South Africa
| | - Omotayo S Alaofin
- Hypertension in Africa Research Team, North-West University, Potchefstroom, 2520, South Africa
| | - Lisa J Ware
- SAMRC/Wits Developmental Pathways for Health Research Unit (DPHRU), University of the Witwatersrand, Soweto, 1864, South Africa
| | - Erika S W Jones
- Division of Nephrology and Hypertension, Groote Schuur Hospital and Kidney and Hypertension Research Unit, University of Cape Town, Cape Town, South Africa
| | - Andre Pascal Kengne
- Non-Communicable Diseases Research Unit, South African Medical Research Council, Francie Van Zijl Dr, Parow Valley, Cape Town, 7501, South Africa
- Department of Biological and Environmental Sciences, Faculty of Natural Sciences, Walter Sisulu University, Mthatha, South Africa
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Tade G, Hsu HC, Robinson C, Dlongolo N, Teckie G, Solomon A, Dessein PH. The relative potential contribution of volume load and vascular mechanisms to hypertension in non-dialysis and dialysis chronic kidney disease patients. Front Cardiovasc Med 2024; 11:1377887. [PMID: 38689863 PMCID: PMC11060794 DOI: 10.3389/fcvm.2024.1377887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 03/28/2024] [Indexed: 05/02/2024] Open
Abstract
Background Hypertension is highly prevalent and particularly difficult to treat adequately in patients with chronic kidney disease (CKD). The relative contribution of volume overload and vascular mechanisms to blood pressure measures in CKD and whether these effects differ in non-dialysis compared to dialysis patients is unknown. Methods We determined the potential impact of volume load (stroke volume) and vascular mechanisms (inverse of total arterial compliance (inv TAC) and systemic vascular resistance (SVR)) on mean and brachial and aortic systolic blood pressures in 67 non-dialysis and 48 dialysis chronic kidney disease (CKD) patients. Relationships were determined in confounder adjusted regression models. Results Stroke volume (p value = 0.003) was more strongly associated with mean arterial pressure than SVR (p value = 0.9) (p value for difference = 0.03). When stroke volume and SVR were entered in the same regression model (model R2 = 0.324), they contributed equally to the variation in mean arterial pressure (p value for difference = 0.5). Stroke volume (p value ≤ 0.002) and inv TAC (p value ≤ 0.001) contributed equally to the variation in systolic pressures (p value for difference ≥ 0.9). When stroke volume and inv TAC were entered in the same regression model (model R2 = 0.752 to 0.765), they contributed equally to the variation in systolic blood pressures (p value for difference = 0.7). Stroke volume, TAC and SVR were similar (p value ≥ 0.5) and associated to the same extent with blood pressure measures in non-dialysis and dialysis CKD patients (p value for difference ≥ 0.1). In receiver operator characteristic curve analysis, elevated systolic blood pressure was determined by stroke volume (p value = 0.005) and inv TAC (p value = 0.03) but not SVR (p value = 0.8). The calculated power of the study was 0.999 based on α = 0.05. Conclusions The present investigation suggests that both volume load and vascular mechanisms should be considered in the management of hypertension among patients with CKD. The extent and relative potential impact of volume load and vascular mechanisms on blood pressure measures are as large in non-dialysis compared to dialysis CKD patients.
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Affiliation(s)
- Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, Faculty of Health Sciences, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Hon-Chun Hsu
- Cardiovascular Pathophysiology and Genomics Research Unit, Faculty of Health Sciences, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- Nephrology Unit, Milpark Hospital, Johannesburg, South Africa
| | - Chanel Robinson
- Cardiovascular Pathophysiology and Genomics Research Unit, Faculty of Health Sciences, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Noluntu Dlongolo
- Rheumatology Unit, Rosebank Hospital, Johannesburg, South Africa
| | - Gloria Teckie
- Division of Nephrology, Department of Medicine, Chris Hani Baragwanath Hospital and Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Ahmed Solomon
- Internal Medicine Department, University of the Witwatersrand, Johannesburg, South Africa
| | - Patrick Hector Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, Faculty of Health Sciences, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- Rheumatology Unit, Rosebank Hospital, Johannesburg, South Africa
- Internal Medicine Department, University of the Witwatersrand, Johannesburg, South Africa
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Yusuf SM, Norton GR, Peterson VR, Mthembu N, Libhaber CD, Tade G, Bello H, Bamaiyi AJ, Mmopi KN, Dessein PH, Peters F, Sareli P, Woodiwiss AJ. Role of atrial natriuretic peptide in the dissociation between flow relations with ventricular mass and function in a community with volume-dependent hypertension. Front Cardiovasc Med 2023; 10:1175145. [PMID: 37265568 PMCID: PMC10230032 DOI: 10.3389/fcvm.2023.1175145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/26/2023] [Indexed: 06/03/2023] Open
Abstract
Background Whether differential effects of volume load on left ventricular mass (LVM) and function occur in sustained volume-dependent primary hypertension, and the impact of atrial natriuretic peptide (ANP) on these effects, is unknown. Methods From aortic pressure, velocity and diameter measurements and echocardiography, we determined in an African community (n = 772), the impact of systemic flow-induced increases in central pulse pressure (PPc) and circulating ANP (ELISA) on LVM and indexes of function. Results Stroke volume (SV), but not aortic flow (Q), was associated with LVM and mean wall thickness (MWT) beyond stroke work and confounders (p < 0.0001). Adjustments for SV markedly decreased the relationships between PPc and LVMI or MWT. However, neither SV, nor Q were independently associated with either myocardial s', e', or E/e' (p > 0.14) and adjustments for neither SV nor Q modified relationships between PPc and s', e' or E/e' (p < 0.005 to <0.0001). SV was nevertheless strongly and independently associated with ANP (p < 0.0001) and ANP was similarly strikingly associated with s' (p < 0.0001) and e' (p < 0.0005), but not E/e', independent of confounders and several determinants of afterload. Importantly, ANP concentrations were inversely rather than positively associated with LV diastolic dysfunction (DD) (p < 0.005) and lower rather than higher ANP concentrations contributed markedly to the ability to detect DD in those with, but not without LV hypertrophy. Conclusion In populations with sustained volume-dependent hypertension, flow (SV)-related increases in PP have a major impact on LV structure, but not on function, an effect attributed to parallel striking beneficial actions of ANP on myocardial function.
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Yusuf SM, Norton GR, Peterson VR, Malan N, Gomes M, Mthembu N, Libhaber CD, Tade G, Bello H, Bamaiyi AJ, Mmopi KN, Peters F, Sareli P, Dessein PH, Woodiwiss AJ. Attenuated Relationships Between Indexes of Volume Overload and Atrial Natriuretic Peptide in Uncontrolled, Sustained Volume-Dependent Primary Hypertension. Hypertension 2023; 80:147-159. [PMID: 36330806 DOI: 10.1161/hypertensionaha.122.19637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Whether systolic blood pressure (SBP) control in sustained volume-dependent primary hypertension is associated with blunted ANP (atrial natriuretic peptide) relationships with indexes of volume load is unknown. METHODS Systemic hemodynamics (central pressure, echocardiographic aortic velocity and diameter measurements in the outflow tract), circulating ANP concentrations (ELISA assays) and glomerular and tubular function (24-hour urine collections [n=519]) were determined in a community of African ancestry (n=772). RESULTS As compared with those with a controlled SBP, those with an uncontrolled SBP (n=198) showed lower ANP concentrations (P<0.005) despite higher stroke volume and cardiac output (P<0.0001) and renal differences consistent with enhanced fluid retention. In those with a controlled SBP, fractional Na+ excretion (FeNa+; P<0.0005) and creatinine clearance (glomerular filtration rate; P<0.005) were inversely associated with ANP concentrations independent of confounders. Moreover, in those with a controlled SBP, stroke volume and cardiac output (P<0.0001) were independently and positively associated with ANP concentrations. In addition, in those with a controlled SBP, ANP concentrations were independently and inversely associated with systemic vascular resistance (SVR; P<0.0001) and aortic characteristic impedance (Zc; P<0.005). By contrast, in those with uncontrolled SBP, no relationships between either stroke volume (P>0.25), cardiac output (P>0.29), FeNa+ (P>0.77), or glomerular filtration rate (P>0.47) and ANP concentrations were noted. Furthermore, in those with an uncontrolled SBP, no relationships between ANP concentrations and SVR or Zc were observed (P>0.34). CONCLUSIONS In a population where primary hypertension is strongly volume-dependent, those with an uncontrolled SBP have an attenuated relationship between ANP and both renal and hemodynamic indexes of volume overload and the vascular effects of ANP.
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Affiliation(s)
- Suraj M Yusuf
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gavin R Norton
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vernice R Peterson
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nico Malan
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Monica Gomes
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nonhlanhla Mthembu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carlos D Libhaber
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Hamza Bello
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adamu J Bamaiyi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Keneilwe N Mmopi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ferande Peters
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pinhas Sareli
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Patrick H Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Angela J Woodiwiss
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Mthembu N, Norton GR, Peterson VR, Naran R, Yusuf SM, Tade G, Bello H, Bamaiyi A, Libhaber CD, Dessein P, Peters F, Sareli P, Woodiwiss AJ. Contribution of Increases in Late Systolic Ejection Volume to the Impact of Heart Rate on Central Arterial Pulse Pressure in a Community Sample. Am J Hypertens 2022; 35:989-997. [PMID: 35983904 DOI: 10.1093/ajh/hpac097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 07/19/2022] [Accepted: 08/18/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND A lower heart rate (HR) increases left ventricular (LV) ejection volume. Whether this contributes to the adverse effects of HR on central pulse pressure (PPc) through reservoir volume effects is uncertain. METHODS Using noninvasive central pressure, aortic velocity, and diameter measurements in the outflow tract (echocardiography), we assessed the role of LV ejection volume as a determinant of HR relations with PPc in 824 community participants. RESULTS A lower HR was independently associated with both stroke volume (SV) (P < 0.001) and a shift in ejection volume from early (until the first systolic shoulder) to late (from first systolic shoulder to peak PP) systole (P < 0.05 to P < 0.005). Adjustments for LV end diastolic volume markedly diminished HR relations with SV and indexes of the shift in ejection volume to late systole. A lower HR was also independently associated with increases in forward traveling pressure waves (Pf) and PPc (P < 0.0001). However, adjustments for neither SV, nor indexes of a shift in ejection volume to late systole modified HR-Pf or PPc relations. This was despite relationships between indexes of a shift in ejection volume to late systole and both Pf and PPc (P < 0.0001). In contrast, adjustments for the increases in re-reflected and backward traveling wave pressures with a lower HR, eliminated HR-Pf and PPc relations. CONCLUSIONS In contrast to current thought, a lower HR is not associated with increases in PPc through an impact of increases in late systolic ejection volume on aortic reservoir volume, but rather through increases in backward wave pressures.
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Affiliation(s)
- Nonhlanhla Mthembu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gavin R Norton
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vernice R Peterson
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ravi Naran
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Suraj M Yusuf
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Hamza Bello
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adamu Bamaiyi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carlos D Libhaber
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Patrick Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ferande Peters
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pinhas Sareli
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Angela J Woodiwiss
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Mthembu N, Peterson VR, Norton GR, Sadiq E, Kolkenbeck-Ruh A, Naran R, Yusuf SM, Tade G, Bello H, Bamaiyi A, Libhaber CD, Dessein P, Peters F, Monareng T, Abdool-Carrim T, Cassimjee I, Sareli P, Modi G, Woodiwiss AJ. Proximal aortic stiffness modifies the relationship between heart rate and backward wave and hence central arterial pulse pressure. Front Cardiovasc Med 2022; 9:971141. [PMID: 36337883 PMCID: PMC9626514 DOI: 10.3389/fcvm.2022.971141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/21/2022] [Indexed: 12/01/2023] Open
Abstract
AIMS A lower heart rate (HR) increases central blood pressure through enhanced backward wave pressures (Pb). We aimed to determine whether these relationships are modified by increases in aortic stiffness. METHODS Using non-invasive central pressure, aortic velocity and diameter measurements in the outflow tract (echocardiography), we assessed the impact of aortic stiffness on relationships between HR and arterial wave morphology in 603 community participants < 60 years of age, 221 ≥ 60 years, and in 287 participants with arterial events [stroke and critical limb ischemia (CLI)]. RESULTS As compared to community participants < 60 years, those ≥ 60 years or with events had increased multivariate adjusted proximal aortic characteristic impedance (Zc) and carotid femoral pulse wave velocity (PWV) (p < 0.05 to < 0.0001). Community participants ≥ 60 years and those with events also had a greater slope of the inverse relationship between HR and Pb (p < 0.001 for comparison). While in community participants < 60 years, no interaction between indexes of aortic stiffness and HR occurred, in those ≥ 60 years (p < 0.02) and in those with arterial events (p = 0.001), beyond aortic root diameter, an interaction between Zc and HR, but not between PWV and HR independently associated with Pb. This translated into stepwise increases in the slope of HR-Pb relationships at incremental tertiles of Zc. Although HR was inversely associated with the systemic reflection coefficient in community participants ≥ 60 years (p < 0.0001), adjustments for the reflection coefficient failed to modify HR-Pb relations. CONCLUSION Beyond the impact on systemic wave reflection, increases in proximal aortic stiffness enhance the adverse effects of HR on Pb and hence central BP.
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Affiliation(s)
- Nonhlanhla Mthembu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vernice R. Peterson
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gavin R. Norton
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Eitzaz Sadiq
- School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrea Kolkenbeck-Ruh
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ravi Naran
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Suraj M. Yusuf
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Hamza Bello
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adamu Bamaiyi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carlos D. Libhaber
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Patrick Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ferande Peters
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Taalib Monareng
- School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Talib Abdool-Carrim
- School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ismail Cassimjee
- School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pinhas Sareli
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Girish Modi
- School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Angela J. Woodiwiss
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Mthembu N, Norton GR, Peterson VR, Naran R, Yusuf SM, Tade G, Bello H, Bamaiyi A, Libhaber CD, Dessein P, Peters F, Sareli P, Woodiwiss AJ. Increased Backward Wave Pressures Rather than Flow Explain Age-Dependent Heart Rate Effects on Central, But not Peripheral Arterial Pressure. Hypertension 2021; 79:435-446. [PMID: 34852646 DOI: 10.1161/hypertensionaha.121.18271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Through both backward (Pb) and forward (Pf) wave effects, a lower heart rate (HR) associates with increased central (PPc), beyond brachial pulse pressure (PP). However, the relative contribution to Pf of aortic flow (Q) versus re-reflection of Pb, has not been determined. Using central pressure, aortic velocity and diameter measurements in the outflow tract (echocardiography), we constructed central pressure waveforms that account for the relative contribution of Q versus re-reflection to Pf. We thus evaluated the mechanisms of HR-PPc relations in a community sample (n=824) and the impact of age thereon. Inverse HR-PPc (P<0.0001), but not HR-brachial PP (P=0.064) relations were noted. The slope of HR-PPc relation was increased in older adults (P<0.005). HR was inversely associated with ventricular filling time, ejection duration, stroke volume, and peak Pf (P<0.001 to P<0.0001). However, an increased Q and hence pressures generated by the product of aortic characteristic impedance and Q did not account for Pf effects. Age-dependent HR-PPc and Pf relations were both accounted for by enhanced Pb (P<0.0001) with an increased Pf mediated by increments in wave re-reflection (P<0.0001). The lack of impact of ejection duration on PPc was explained by an increased time to peak Pb (P<0.0001). In conclusion, increases in PPc and Pf at a decreased HR are accounted for by an enhanced Pb rather than by a prolonged ejection or filling duration and hence flow (Q). These effects at a young-to-middle age are of little clinical significance, but at an older age, are of clinical importance.
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Affiliation(s)
- Nonhlanhla Mthembu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gavin R Norton
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vernice R Peterson
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ravi Naran
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Suraj M Yusuf
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Grace Tade
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Hamza Bello
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adamu Bamaiyi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carlos D Libhaber
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Patrick Dessein
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ferande Peters
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pinhas Sareli
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Angela J Woodiwiss
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Independent relationships between renal mechanisms and systemic flow, but not resistance to flow in primary hypertension in Africa. J Hypertens 2021; 39:2446-2454. [PMID: 34738989 DOI: 10.1097/hjh.0000000000002968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AIMS Whether renal mechanisms of hypertension primarily translate into increases in systemic vascular resistance (SVR) in all populations is uncertain. We determined whether renal mechanisms associate with either increases in SVR (and impedance to flow) or systemic flow in a community of African ancestry. METHOD In a South African community sampled across the full adult age range (n = 546), we assessed stroke volume (SV), peak aortic flow (Q), SVR, characteristic impedance (Zc) and total arterial compliance (TAC) from velocity and diameter measurements in the outflow tract (echocardiography) and central arterial pressures. Renal changes were determined from creatinine clearance (glomerular filtration rate, GFR) and fractional Na+ excretion (FeNa+) (derived from 24-h urine collections). RESULTS Independent of confounders (including MAP and pressures generated by the product of Q and Zc), SV (and hence cardiac output) (P < 0.0001) and Q (P < 0.01), but not SVR, Zc or TAC (P = 0.09-0.20) were independently associated with decreases in both GFR (index of nephron number) and FeNa+. Through an interactive effect (P < 0.0001), the impact of GFR on SV or Q was strongly determined by FeNa+ and vice versa. The relationship between the GFR-FeNa+ interaction and either SV or Q was noted in those above or below 50 years of age, although neither GFR, FeNa+ nor the interaction were independently associated with SVR, Zc or TAC at any age. CONCLUSION Across the full adult lifespan, in groups of African ancestry, renal mechanisms of hypertension translate into increases in systemic flow rather than into resistance or impedance to flow.
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Bello H, Norton GR, Peterson VR, Libhaber CD, Mmopi KN, Mthembu N, Masiu M, Da Silva Fernandes D, Bamaiyi AJ, Peters F, Sareli P, Woodiwiss AJ. Hemodynamic and Functional Correlates of Concentric vs. Eccentric LVH in a Community-Based Sample With Prevalent Volume-Dependent Hypertension. Am J Hypertens 2021; 34:1300-1310. [PMID: 34379750 DOI: 10.1093/ajh/hpab128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/28/2021] [Accepted: 08/10/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Whether in volume-dependent primary hypertension, concentric left ventricular (LV) remodeling beyond hypertrophy (LVH) represents the impact of a pressure rather than a volume overload, is unclear. METHODS Using central arterial pressure, and aortic velocity and diameter measurements in the outflow tract (echocardiography), we determined the factors that associate with concentric LVH or remodeling in a community of African ancestry (n = 709) with prevalent volume-dependent primary hypertension. RESULTS Both left ventricular mass index (LVMI) and relative wall thickness (RWT) were positively and independently associated with end diastolic volume (EDV), stroke volume (SV), and peak aortic flow (Q) (P < 0.05 to <0.0001). However, neither LVMI nor RWT were positively and independently associated with systemic vascular resistance (SVR), or aortic characteristic impedance (Zc) or inversely associated with total arterial compliance (TAC). Consequently, both concentric (P < 0.0001) and eccentric (P < 0.0001) LVH were associated with similar increases in EDV, SV, and either office brachial, central arterial, or 24-hour blood pressures (BP), but neither increases in SVR or Zc nor decreases in TAC. LV RWT, but not LVMI was nevertheless independently and inversely associated with myocardial systolic function (midwall shortening and s') (P < 0.05 to <0.005) and decreases in LV systolic function were noted in concentric (P < 0.05), but not eccentric LVH. CONCLUSIONS In volume-dependent primary hypertension, concentric LVH is determined as much by volume-dependent increases in systemic flow and an enhanced BP as eccentric LVH. Concentric remodeling nevertheless reflects decreases in systolic function beyond LVH.
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Affiliation(s)
- Hamza Bello
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gavin R Norton
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vernice R Peterson
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carlos D Libhaber
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Keneilwe N Mmopi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nonhlanhla Mthembu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Mohlabani Masiu
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Daniel Da Silva Fernandes
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adamu J Bamaiyi
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ferande Peters
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pinhas Sareli
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Angela J Woodiwiss
- Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Impact of stroke work on the ability of left ventricular mass to account for pressure effects on function in a community with prevalent systemic flow-dependent hypertension. J Hypertens 2021; 39:2092-2102. [PMID: 34232159 DOI: 10.1097/hjh.0000000000002896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS To determine whether the confounding influence of stroke work on left ventricular mass (LVM) limits the ability of LVM to detect hypertensive LV dysfunction in systemic flow-dependent hypertension. METHODS In a community with prevalent systemic flow-dependent hypertension (n = 709), arterial haemodynamics, LVM and LV function were determined using central arterial pressure, aortic velocity and diameter measurements in the outflow tract, and echocardiography with tissue Doppler imaging. RESULTS In multivariate models, stroke work showed markedly stronger relations with LVM index (LVMI) than blood pressure load [central arterial SBP (SBPc), backward wave pressure (Pb), 24-h SBP] (P < 0.0001 for comparisons). In contrast, although SBPc, Pb, and 24-h SBP were inversely associated with myocardial tissue shortening (s') and lengthening (e') velocity, stroke work was not. With adjustments for stroke work, positive relationships between SBPc, Pb, or 24-h SBP and LVMI were eliminated (P = 0.20 to P = 0.89), but strong relations between BP and s', e' or E/e' (P = 0.009 to P < 0.0001) remained. In mediation analysis, stroke work fully accounted for BP effects on LVMI, but explained none of the effects of BP on LV function. Hence LVMI accounted for little of the impact of BP load on LV function. Although LVMI beyond stroke work (inappropriate LVM) improved on relations between LVMI and s', it failed to improve on relations with e' or E/e' and contributed little beyond LVMI to the impact of BP on LV function. CONCLUSION In systemic flow-dependent hypertension, the impact of stroke work markedly limits the ability of LVM to account for adverse effects of hypertension on LV function.
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Contribution of systemic blood flow to untreated or inadequately controlled systolic--diastolic or isolated systolic hypertension in a community sample of African ancestry. J Hypertens 2020; 39:526-537. [PMID: 32868640 DOI: 10.1097/hjh.0000000000002635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS Age-related increases in systemic blood flow [stroke volume (SV), cardiac output (CO), and aortic flow (Q)] contribute substantially to untreated or inadequately controlled (uncontrolled) blood pressure (BP) in Africa. We aimed to identify the haemodynamic determinants of uncontrolled systolic--diastolic (Syst--diast HT) versus uncontrolled isolated systolic (ISH) or diastolic (IDH) hypertension. METHODS Using central arterial pressure and aortic outflow tract velocity and diameter measurements (echocardiography), the haemodynamic correlates of BP were determined in 725 community participants of African ancestry (19.6% uncontrolled Syst--diast HT, 9.2% uncontrolled ISH, 11.3% uncontrolled IDH). RESULTS Independent of confounders, compared with those with a normotensive BP, those with uncontrolled Syst--diast HT had increases in SV, CO, Q, systemic vascular resistance (SVR) and aortic characteristic impedance (Zc) and decreases in total arterial compliance (TAC) (P < 0.05--P < 0.0001). In multivariate regression models, uncontrolled Syst--diast HT was as strongly associated with Q, SV or CO as with SVR (P = 0.04--P = 0.20), Zc (P = 0.74--P < 0.0005) and TAC (P = 0.43--P < 0.005). Independent of confounders, compared with normotensive individuals those with uncontrolled ISH had increases in SV, CO, Q and Zc but not SVR, and decreases in TAC (P < 0.05-P < 0.0001), and those with IDH only had increases in SVR (P < 0.0001). Uncontrolled ISH was more strongly associated with Q, SV and CO than with SVR (P < 0.0005), but less than with TAC (P < 0.05--P < 0.0005). CONCLUSION In groups of African ancestry living in Africa, hypertension because of increases in either SBP or DBP is as strongly associated with increases in systemic flow (SV, Q) as with arterial and arteriolar effects (Zc, TAC, SVR).
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