Biomedical subjects

Emma Hart

Publications and source records attributed to Emma Hart.

4 recordsLinked to original sources

PubMed2026

Assessing the impact of maternal blood pressure during pregnancy on perinatal health: a wide-angled Mendelian randomization study.

BACKGROUND: Observational studies link high blood pressure in pregnancy to numerous adverse pregnancy and perinatal outcomes; however, findings may be affected by residual confounding or reverse causation. This study aimed to assess the causal effect of blood pressure during pregnancy on a range of pregnancy and perinatal outcomes. METHODS: We performed two-sample Mendelian randomization (MR) to assess the effect of systolic and diastolic blood pressure (SBP/DBP) during pregnancy on 16 primary and eight secondary adverse pregnancy and perinatal outcomes. We obtained genetic association data from large-scale meta-analyses of genome-wide association studies involving predominantly European ancestry individuals for SBP/DBP (N = 1,028,980), and pregnancy and perinatal outcomes (N = 74,368-714,899). We used inverse-variance weighted (IVW) MR for main analyses and MR-Egger, weighted median, weighted mode, multivariable MR, and IVW adjusted for fetal genetic effects for sensitivity analyses. RESULTS: A 10 mmHg higher genetically predicted maternal SBP increased the odds of gestational diabetes, induction of labour, low birth weight (LBW), small-for-gestational age (SGA), preterm birth (PTB), and neonatal intensive care unit (NICU) admission (OR ranging from 1.11 [95% CI 1.02 to 1.20] for NICU admission to 1.33 [1.26 to 1.41] for LBW); while decreasing the odds of high birth weight (HBW), large-for-gestational age (LGA), and post-term birth [OR ranging from 0.76 (0.69 to 0.83) for HBW to 0.94 (0.90 to 0.99) for post-term birth]. We did not find evidence that genetically predicted higher maternal SBP was related to miscarriage or stillbirth. The results for maternal DBP were similar to the results for SBP. Overall, the main results were consistent across sensitivity analyses accounting for pleiotropic instruments and fetal genetic effects. CONCLUSIONS: Higher maternal blood pressure reduces gestation duration and fetal growth and increases the risks of induction of labour, gestational diabetes, and neonatal intensive care unit admission. This and other emerging evidence highlight the value of interventions aimed at controlling blood pressure in the population to reduce the burden of adverse pregnancy outcomes.

Humans↗

PubMed2007

Altered left ventricular diastolic filling following a marathon is a reproducible phenomenon.

The present study examined the reproducibility of alterations in left ventricular function and cardiac biomarkers in a cohort of athletes following two marathons, one year apart. Eight participants in the 2004 and 2005 London Marathons were tested pre- and post-race via echocardiography and humoral analysis. Reductions in diastolic filling, unrelated to loading or heart rate, following both marathons were reproducible within individuals, which may be a function of exercise duration. In contrast, exercise-induced cardiac troponin release was inconsistent.

Adult↗

PubMed2006

Beta-adrenergic receptor desensitization in man: insight into post-exercise attenuation of cardiac function.

Desensitization of the beta-adrenoreceptors (beta-AR) may contribute to a post-exercise reduction in left ventricular (LV) function. However, attenuation of the chronotropic and inotropic responses to a beta-AR agonist may depend upon alterations in parasympathetic tone. Furthermore, changes in cardiac output and LV diastolic function in response to a beta-AR agonist, pre- to post-prolonged exercise, remain unclear. Seven trained males (mean+/-s.d., age 27+/-6 years) performed 4 h of ergometer rowing. Peak heart rate (HR) and LV systolic and diastolic functional responses to incremental isoproterenol (isoprenaline) infusion (2, 4 and 6 microg kg min-1) were assessed after vagal blockade (glycopyrrolate, 1.2 mg). LV systolic function was assessed by the pressure/volume ratio (systolic blood pressure/end systolic volume) and , whilst diastolic function was evaluated as peak early and late transmitral filling velocities. Following exercise, the pressure/volume ratio decreased by 25% (P<0.05), whereas was unchanged (P>0.05). The early/late filling ratio was reduced by 36% after exercise, due to an elevation in late LV filling (P<0.01). The increase in HR response to isoproterenol infusion was blunted post-exercise at both 4 and 6 microg kg min-1 (127+/-7 and 132+/-6 beats min-1) compared with pre-exercise (138+/-8 and 141+/-12 beats min-1, P<0.05). Additionally, the pressure/volume ratio and were blunted post-exercise in response to isoproterenol (P<0.05). In contrast, diastolic function was similar before and after exercise during isoproterenol infusion (P>0.05). Desensitization of the beta-AR contributes to an attenuated left ventricular systolic but not diastolic function following prolonged exercise.

Adrenergic beta-Agonists↗

PubMed2006

Left ventricular function immediately following prolonged exercise: A meta-analysis.

PURPOSE: Evidence supporting cardiac fatigue following prolonged endurance exercise remains equivocal. The purpose of this meta-analysis was to quantify all data fulfilling the specified inclusion criteria, examining the short-term effect of prolonged endurance exercise on left ventricular function. METHODS: A random effects meta-analysis of the weighted mean change in ejection fraction (EF), systolic blood pressure/end systolic volume (SBP/ESV) ratio, and early-to-late diastolic filling (E/A) was conducted on 23 studies using the SE of the between-subjects SD. HR, SBP, and left ventricular internal diameter during diastole (LVIDd) were also analyzed. Studies were coded according to exercise duration and training status: moderate duration trained (MDt) and untrained (MDu), 60-150 min; long duration (LD), 166-430 min; and ultra duration (UD), 640-1440 min. Relationships were assessed via Pearson's product-moment correlation. RESULTS: A significant (P < 0.05) overall decrease in EF (mean, confidence interval (CI): -1.95%, -1.03 to -2.88%), SBP/ESV (mean, CI: -0.8, -0.63 to -0.97), and E/A (mean, CI: -0.45, -0.39 to -0.51) was observed. Only UD and MDu subgroups demonstrated a reduction in EF. All subgroups demonstrated significant (P < 0.05) decreases in E/A. Alterations in LVIDd and SBP were related to respective decreases in EF and SBP/ESV, but not to E/A. CONCLUSION: The decrease in EF and SBP/ESV observed in UD and MDu indicates a reduction in systolic function, partially explained by altered cardiac loading. A decrease in E/A in all subgroups, unrelated to changes in loading, suggests an intrinsic impairment of left ventricular relaxation. Future investigators should employ load-independent indices of cardiac function and attempt to uncover the mechanisms of this phenomenon.

Echocardiography↗