Jane Thompson

Left ventricular mechanics in humans with high aerobic fitness: adaptation independent of structural remodelling, arterial haemodynamics and heart rate

Key points  •  During cardiac contraction, left ventricular (LV) mechanics play an important role in equalising transmural fibre stress and ensuring efficient ejection of blood. •  The factors responsible for altered LV mechanics in humans with high aerobic exercise capacity are unknown but are believed to be related to changes in LV structure or heart rate. •  We performed a comprehensive assessment of LV mechanics and cardiovascular function at rest and during dynamic exercise in individuals with moderate and high aerobic exercise capacity. •  Our novel data indicate that there is no direct association between altered LV mechanics in humans with high aerobic fitness and classic indicators of cardiovascular adaptation. •  The findings provide evidence of a previously unknown type of physiological LV adaptation that may have important implications for exercise training in various healthy and diseased populations.

Masked hypertension and its associated cardiovascular risk in young individuals: the African-PREDICT study.

Hypertension prevalence is increasing globally, yet little is known about the occurrence of masked hypertension (MHT) in young, sub-Saharan African adults, and how it relates to elevated cardiovascular risk. The African-PREDICT study (recruitment based on normotensive clinic blood pressure (BP)) determined the frequency of MHT and its relationship with arterial stiffness and biochemical markers of inflammation and endothelial activation. We included men and women (n=352), 20–30 years, screened for normotensive clinic BP (54% white, 40% men). Clinic BP, ambulatory blood pressure monitoring (ABPM), central systolic pressure, aortic pulse wave velocity (aPWV), augmentation index, anthropometry, physical activity and biochemical markers of cardiovascular risk were assessed (lipids, glucose, insulin, markers of endothelial activation and inflammation). Eighteen percent of the study population had MHT (60% white, 68% men). Those with MHT had increased adiposity, clinic-, ABPM- (24-h, day and night) and central-BP (within normal ranges), heart rate, aPWV and biochemical markers of cardiovascular risk, compared with normotensives (all P<0.05). Using multivariable adjusted odds ratios, we found that MHT was associated with increased likelihood for higher aPWV (odds ratio (OR)=1.567, P=0.010), insulin (OR=1.499, P=0.049), monocyte chemoattractant protein-1 (OR=1.499, P=0.026), vascular cellular adhesion molecule (OR=1.409, P=0.042) and C-reactive protein (OR=1.440, P=0.044). In a young adult (supposedly healthy) cohort, the occurrence of MHT is alarming, especially since MHT further demonstrated elevated cardiovascular risk via increased adiposity, arterial stiffness, endothelial activation and inflammation. Detection of MHT is crucial to increase awareness of elevated cardiovascular risk, and to ensure the required lifestyle and/or pharmaceutical interventions.

Evaluation of cardiovascular risk-lowering health benefits accruing from laboratory-based, community-based and exercise-referral exercise programmes

Background To evaluate the ability of community-based exercise programmes to facilitate public participation in exercise and hence improved cardiovascular health, we assessed the respective impacts of: a continuously monitored exercise programme based within our university (study 1); a Valleys Regional Park-facilitated community-based outdoor exercise programme (study 2); a Wales National Exercise Referral Scheme-delivered exercise-referral programme (study 3). Methods Biomolecular (monocytic PPARγ target gene expression), vascular haemodynamic (central/peripheral blood pressure, arterial stiffness), clinical (insulin sensitivity, blood lipids) and anthropometric (body mass index, waist circumference, heart rate) parameters were investigated using RT-PCR, applanation tonometry, chemical analysis and standard anthropometric techniques. Results In studies 1–3, 22/28, 32/65 and 11/14 participants adhered to their respective exercise programmes, and underwent significant increases in physical activity levels. Importantly, beneficial effects similar to those seen in our previous studies (eg, modulations in expression of monocytic PPARγ target genes, decreases in blood pressure/arterial stiffness, improvements in blood lipids/insulin sensitivity) were observed (albeit to slightly differing extents) only in participants who adhered to their respective exercise programmes. While study 1 achieved more intense exercise and more pronounced beneficial effects, significant cardiovascular risk-lowering health benefits related to biomolecular markers, blood pressure, arterial stiffness and blood lipids were achieved via community/referral-based delivery modes in studies 2 and 3. Conclusions Because cardiovascular health benefits were observed in all 3 studies, we conclude that the majority of benefits previously reported in laboratory-based studies can also be achieved in community-based/exercise-referral settings. These findings may be of use in guiding policymakers with regard to introduction and/or continued implementation of community/referral-based exercise programmes.

Carotid artery wall mechanics in young males with high cardiorespiratory fitness

What is the central question of this study? Common carotid artery (CCA) two‐dimensional strain imaging detects intrinsic arterial wall properties beyond conventional measures of arterial stiffness, but the effect of cardiorespiratory fitness on two‐dimensional strain‐derived indices of CCA stiffness is unknown. What is the main finding and its importance? Two‐dimensional strain imaging of the CCA revealed greater peak circumferential strain and systolic strain rate in highly fit men compared with their less fit counterparts. Altered CCA wall mechanics might reflect intrinsic training‐induced adaptations that help to buffer the increase in pulse pressure and stroke volume during exercise.

6A.08: HIGH FREQUENCY OF MASKED HYPERTENSION AND ASSOCIATED ARTERIAL STIFFNESS IN AFRICANS.

Objective: While South Africa has one of the highest rates of hypertension globally, data on masked and white coat hypertension in the region is scant. This study sought to determine the frequency of masked and white coat hypertension in low income South African adults and to evaluate cardiovascular risk through measures of arterial stiffness. Design and method: We included 81 low income adults (50% men, 96% black, 4% coloured) aged 19–63 years, and measured clinic blood pressure four times (twice on each upper arm) with the Omron M10-IT automated device; also 24 hour ambulatory blood pressure with pulse wave analysis (Mobil-O-Graph ABPM), anthropometry and HIV status. We collected sociodemographic, stress and depression data by questionnaires. Results: When viewing hypertension criteria for both clinic and ambulatory BP, we found that 15% complied to all criteria, classified as sustained hypertensives; 3% had white coat hypertension; and 48% had masked hypertension. The sustained hypertension group had a higher mean body mass index and waist circumference than both the masked hypertension and normotensive groups (p = 0.004 and p = 0.007). Both the sustained hypertensives and masked hypertensives presented elevated 24-hour, daytime and nighttime pulse wave velocity compared to normotensives (all p < 0.001), but we found no differences between the sustained and masked hypertensives for pulse wave velocity and augmentation index. Other traditional cardiovascular risk factors including smoking, alcohol consumption, physical activity levels, occupation, stress or depression were also comparable between sustained and masked hypertensives. Conclusions: Almost half of African adults measured had masked hypertension and individuals presented comparable estimates for arterial stiffness to Africans with sustained hypertension. Since masked hypertension cannot be detected by clinic blood pressure measurement alone, these results may have far-reaching implications in hypertension detection, treatment and control strategies, and imply underestimations of country-specific hypertension prevalence rates. Further studies are required to determine the most cost effective method to detect undiagnosed hypertension cases in the African region.