Differences between brachial and aortic blood pressure in adolescence and their implications for diagnosis of hypertension.

OBJECTIVES: Blood pressure (BP) is the leading global cause of mortality, and its prevalence is increasing in children and adolescents. Aortic BP is lower than brachial BP in adults. We aimed to assess the extent of this difference and its impact on the diagnosis of hypertension among adolescents. METHODS: We used data from 3850 participants from a UK cohort of births in the early 1990s in the Southwest of England, who attended their ∼17-year follow-up and had valid measures of brachial and aortic BP at that clinic [mean (SD) age 17.8 (0.4) years, 66% female individuals]. Data are presented as mean differences [95% prediction intervals] for both sexes. RESULTS: Aortic systolic BP (SBP) was lower than brachial SBP [male, -22.3 (-31.2, -13.3) mmHg; female, -17.8 (-25.5, -10.0) mmHg]. Differences between aortic and brachial diastolic BP (DBP) were minimal. Based on brachial BP measurements, 101 male individuals (6%) and 22 female individuals (1%) were classified as hypertensive. In contrast, only nine male individuals (<1%) and 14 female individuals (<1%) met the criteria for hypertension based on aortic BP, and the predictive value of brachial BP for aortic hypertension was poor (positive-predictive value = 13.8%). Participants with aortic hypertension had a higher left ventricular mass index than those with brachial hypertension. CONCLUSION: Brachial BP substantially overestimates aortic BP in adolescents because of marked aortic-to-brachial pulse pressure amplification. The use of brachial BP measurement may result in an overdiagnosis of hypertension during screening in adolescence.

Is Height2.7 Appropriate for Indexation of Left Ventricular Mass in Healthy Adolescents? The Importance of Sex Differences.

BACKGROUND: Left ventricular mass (LVM) is an important predictor of cardiovascular risk. In adolescence, LVM is commonly indexed to height2.7, although some evidence suggests that this may not fully account for sex differences. METHODS: We investigated appropriate allometric scaling of LVM to height, total lean mass, and body surface area, in a UK birth cohort of 2039 healthy adolescents (17±1 years). Allometric relationships were determined by linear regression stratified by sex, following log transformation of x and y variables [log(y)=a+b×log(x)], b is the allometric exponent. RESULTS: Log (LVM) showed linear relationships with log(height) and log(lean mass). Biased estimates of slope resulted when the sexes were pooled. The exponents were lower than the conventional estimate of 2.7 for males (mean [95% CI]=1.66 [1.30-2.03]) and females (1.58 [1.27-1.90]). When LVM was indexed to lean mass, the exponent was 1.16 (1.05-1.26) for males and 1.07 (0.97-1.16) for females. When LVM was indexed to estimated body surface area, the exponent was 1.53 (1.40-1.66) for males and 1.34 (1.24-1.45) for females. CONCLUSIONS: Allometric exponents derived from pooled data, including men and women without adjustment for sex were biased, possibly due to sex differences in body composition. We suggest that when assessing LVM, clinicians should consider body size, body composition, sex, and age. Our observations may also have implications for the identification of young individuals with cardiac hypertrophy.

Mechanisms of Aortic Flow Deceleration and the Effect of Wave Reflection on Left Ventricular Function.

Increased wave reflection is an independent predictor of cardiovascular events, possibly due to effects on left ventricular (LV) function. We investigated the relationship between reflected waves in early systole, the forward decompression wave in mid-late systole and LV mechanical behavior. Invasively acquired ascending aortic velocity, pressure, and LV long and minor axes' dimensions were measured simultaneously in 11 anesthetized dogs during both control conditions and aortic occlusion to cause additional early wave reflection. Wave intensity analysis (WIA) was used to identify the arrival of the reflected wave and the onset of a forward decompression wave in mid-late systole. The arrival time of the reflected wave coincided with the time when minor axis shortening began to decline from its peak, even during aortic occlusion when this time is 12 ms earlier. The initial decline in long axis shortening corresponded to the time of the peak of the reflected wave. The forward decompression wave was consistently observed to have a slow and then rapid phase. The slow phase onset coincided with time of maximum shortening velocity of the long axis. The onset of the later larger rapid phase consistently coincided with an increased rate of deceleration of both axes during late systole. Forward decompression waves are generated by the LV when the long axis shortening velocity falls. Reflected wave arrival has a detrimental effect on LV function, particularly the minor axis. These observations lend support to suggestions that therapies directed toward reducing wave reflection may be of value in hypertension and cardiovascular disease.

Associations Between Left Ventricular Dysfunction and Brain Structure and Function: Findings From the SABRE (Southall and Brent Revisited) Study.

BACKGROUND: Subclinical left ventricular (LV) dysfunction has been inconsistently associated with early cognitive impairment, and mechanistic pathways have been poorly considered. We investigated the cross-sectional relationship between LV dysfunction and structural/functional measures of the brain and explored the role of potential mechanisms. METHOD AND RESULTS: A total of 1338 individuals (69±6 years) from the Southall and Brent Revisited study underwent echocardiography for systolic (tissue Doppler imaging peak systolic wave) and diastolic (left atrial diameter) assessment. Cognitive function was assessed and total and hippocampal brain volumes were measured by magnetic resonance imaging. Global LV function was assessed by circulating N-terminal pro-brain natriuretic peptide. The role of potential mechanistic pathways of arterial stiffness, atherosclerosis, microvascular disease, and inflammation were explored. After adjusting for age, sex, and ethnicity, lower systolic function was associated with lower total brain (beta±standard error, 14.9±3.2 cm3; P<0.0001) and hippocampal volumes (0.05±0.02 cm3, P=0.01). Reduced diastolic function was associated with poorer working memory (-0.21±0.07, P=0.004) and fluency scores (-0.18±0.08, P=0.02). Reduced global LV function was associated with smaller hippocampal volume (-0.10±0.03 cm3, P=0.004) and adverse visual memory (-0.076±0.03, P=0.02) and processing speed (0.063±0.02, P=0.006) scores. Separate adjustment for concomitant cardiovascular risk factors attenuated associations with hippocampal volume and fluency only. Further adjustment for the alternative pathways of microvascular disease or arterial stiffness attenuated the relationship between global LV function and visual memory. CONCLUSIONS: In a community-based sample of older people, measures of LV function were associated with structural/functional measures of the brain. These associations were not wholly explained by concomitant risk factors or potential mechanistic pathways.

Adverse effect of diabetes and hyperglycaemia on arterial stiffness in Europeans, South Asians, and African Caribbeans in the SABRE study.

OBJECTIVES: Ethnic minority groups in the U.K. experience marked differences in cardiovascular disease risk. We investigated differences in arterial central haemodynamics, stiffness, and load in a tri-ethnic population-based cohort. METHODS: A total of 1312 participants (70 ±â€Š6 years) underwent echocardiography and measurement of brachial and central blood pressure to assess central arterial haemodynamics including central pulse pressure (cPP), arterial stiffness [cPP/stroke volume (SV)], systemic vascular resistance (SVR), and load (Ea). RESULTS: Brachial and central SBPs were similar in all ethnic groups. Compared with Europeans, cPP, cPP/SV, and Ea were higher in South Asians. In contrast, cPP/SV was lower in African Caribbeans despite higher mean arterial pressure, higher SVR, and higher diabetes prevalence. cPP/SV and Ea remained significantly higher in South Asians and significantly lower in African Caribbeans after multivariate adjustment. Diabetes and higher HbA1c were more strongly associated with higher cPP/SV in South Asians than in Europeans (Pinteraction = 0.045 and 0.005, respectively); higher HbA1c was also more strongly associated with increased Ea in South Asians than Europeans (Pinteraction = 0.01). There was no evidence of an interaction between glycaemia and cPP/SV in African Caribbeans. CONCLUSIONS: Compared with Europeans, South Asians have unfavorable arterial function. Diabetes and hyperglycaemia have a more deleterious effect on cPP/SV and Ea in South Asians. In contrast, African Caribbeans have more favourable arterial function than Europeans and South Asians. These differences may contribute to the differential ethnic rates of cardiovascular disease.

Arterial pressure: agreement between a brachial cuff-based device and radial tonometry.

OBJECTIVES: Aortic (central) blood pressure (BP) differs from brachial BP and may be a superior predictor of cardiovascular events. However, its measurement is currently restricted to research settings, owing to a moderate level of operator dependency. We tested a new noninvasive device in a large UK cohort. The device estimates central BP using measurements obtained with an upper arm cuff inflated to suprasystolic pressure. We compared these estimates with those obtained using radial tonometry as well as with invasively acquired measurements of aortic BP in a limited number of individuals. METHODS: Consecutive cuff-based and tonometry-based estimates of the pressure waveform and the central BP were obtained from 1107 individuals (70 ±â€Š6 years). Short-term and long-term reproducibility studies were performed on 28 individuals. Simultaneous cuff-based and invasively measured pressure traces were acquired and compared in an additional six individuals (65 ±â€Š20 years). RESULTS: Central systolic BP, as estimated by the cuff-based device, was found to be highly reproducible (coefficient of variation 4 and 8% for short and long-term reproducibility, respectively) and was comparable to that estimated by tonometry (average difference 3 ±â€Š6  mmHg, intraclass correlation coefficient = 0.91). The cuff-based pressure waveforms were similar to those acquired invasively (cross-correlation coefficient 0.93), and the difference in the estimated central systolic BP was -5 ±â€Š8  mmHg (P = 0.2). CONCLUSION: Cuff-based devices show promise to simplify the measurement of central BP, whilst maintaining a similar fidelity to tonometry. This could lead to improved adoption of estimates of central BP in clinical practice.

Hyperglycemia has a greater impact on left ventricle function in South Asians than in Europeans.

OBJECTIVE Diabetes is associated with left ventricular (LV) diastolic and systolic dysfunction. South Asians may be at particular risk of developing LV dysfunction owing to a high prevalence of diabetes. We investigated the role of diabetes and hyperglycemia in LV dysfunction in a community-based cohort of older South Asians and white Europeans. RESEARCH DESIGN AND METHODS Conventional and Doppler echocardiography was performed in 999 participants (542 Europeans and 457 South Asians aged 58-86 years) in a population-based study. Anthropometry, fasting bloods, coronary artery calcification scoring, blood pressure, and renal function were measured. RESULTS Diabetes and hyperglycemia across the spectrum of HbA1c had a greater adverse effect on LV function in South Asians than Europeans (N-terminal-probrain natriuretic peptide ß ± SE 0.09 ± 0.04, P = 0.01, vs. -0.04 ± 0.05, P = 0.4, P for HbA1c/ethnicity interaction 0.02), diastolic function (E/e' 0.69 ± 0.12, P < 0.0001, vs. 0.09 ± 0.2, P = 0.6, P for interaction 0.005), and systolic function (s' -0.11 ± 0.06, P = 0.04, vs. 0.14 ± 0.09, P = 0.1, P for interaction 0.2). Multivariable adjustment for hypertension, microvascular disease, LV mass, coronary disease, and dyslipidemia only partially accounted for the ethnic differences. Adverse LV function in diabetic South Asians could not be accounted for by poorer glycemic control or longer diabetes duration. CONCLUSIONS Diabetes and hyperglycemia have a greater adverse effect on LV function in South Asians than Europeans, incompletely explained by adverse risk factors. South Asians may require earlier and more aggressive treatment of their cardiometabolic risk factors to reduce risks of LV dysfunction.

Feasibility and reproducibility of left ventricular rotation by speckle tracking echocardiography in elderly individuals and the impact of different software.

BACKGROUND: Changes in ventricular rotation measured by two-dimensional speckle tracking echocardiography (2DSTE) are early indicators of cardiac disease. Data on the clinical feasibility of this important measure are scarce and there is no information on the comparability of different software versions. We assessed the feasibility, reproducibility and within patient temporal variability of 2DSTE in a large community based sample of older adults. We additionally compared 2DSTE results to those generated by 3DSTE. METHODS AND RESULTS: 1408 participants underwent transthoracic echocardiography. Using Philips Qlab 8.1 peak LV rotation at either the base or the apex was analysable in 432 (31%) participants. Peak twist measurements were achieved in 274 (20%) participants. 66 participants were randomly selected for the reproducibility study. 20 additional participants had scans 4-6 weeks apart for temporal variability and 3D echocardiography to assess the agreement between 2DSTE and 3DSTE. Reproducibility was evaluated using the intraclass coefficient of correlation (ICC). Better reproducibility for rotation and twist were obtained when measured at the endocardium, and when using more recent software versions, Peak twist and rotation were significantly different using two versions of the same software. Agreement with 3DSTE was better using newer software. CONCLUSION: Feasibility of 2DSTE is low in this cohort of elderly individuals severely limiting its utility in clinical settings. However if high quality images can be acquired assessment of ventricular rotation by 2DSTE is reproducible. Caution should be taken when comparing measurements of ventricular rotation by software from different vendors or different versions of software from the same vendor.

Left-ventricular structure in the Southall And Brent REvisited (SABRE) study: explaining ethnic differences.

Cardiometabolic risk is elevated in South Asians and African Caribbeans compared with Europeans, yet whether this is associated with ethnic differences in left-ventricular structure is unclear. Conventional M-mode or 2-dimensional echocardiography may be misleading, because they calculate left-ventricular mass and remodeling using geometric assumptions. Left-ventricular structure was compared in a triethnic population-based cohort using conventional and 3-dimensional echocardiography on 895 individuals (aged 55-85 years; 427 European, 325 South Asian, 143 African Caribbean). Left-ventricular mass was indexed, and left-ventricle remodeling index and relative wall thickness were calculated. Anthropometry, blood pressure, and fasting bloods were measured. Three-dimensional left-ventricular mass index did not differ between Europeans (mean ± SE, 29.8 ± 0.3 g/m(2.7)) and African Caribbeans (29.9 ± 0.5 g/m(2.7); P=0.9), but it was significantly lower in South Asians (28.1 ± 0.4 g/m(2.7); P<0.0001) compared with Europeans. These findings persisted on multivariate adjustment. In contrast, conventional left-ventricle mass index was significantly higher in African Caribbeans (46.4 ± 0.9 g/m(2.7)) than in Europeans (41.9 ± 0.5 g/m(2.7); P<0.0001). Left-ventricle remodeling index was the highest in African Caribbeans and the lowest in South Asians. Relative wall thickness was also higher in African Caribbeans, but no different in South Asians, compared with Europeans. Differences in left-ventricle remodeling index were attenuated by adjustment for cardiometabolic factors between African Caribbeans and Europeans only. In conclusion, left-ventricular mass is lower in South Asians and equivalent in African Caribbeans compared with Europeans, even when cardiometabolic risk factors are accounted for. Left-ventricular remodeling rather than hypertrophy may explain the increased risk of heart failure in people of African Caribbean origin.