Higher cardiac vagal activity predicts lower peripheral resistance 6 years later in European but not African Americans.

African American (AA) individuals are at a greater risk for the development of cardiovascular complications, such as hypertension, compared with European Americans (EAs). Higher vagally mediated heart rate variability (HRV) is typically associated with lower blood pressure (BP) and total peripheral resistance (TPR). However, research has yet to examine the differential impact of HRV on longitudinal hemodynamic activity between AAs and EAs. We sought to rectify this in a sample of 385 normotensive youths (207 AAs, 178 EAs; mean age 23.16 ± 2.9 yr). Individuals participated in two laboratory evaluations spanning approximately 6 yr. Bioimpedance was used to assess HRV at time 1 and cardiac output at both time 1 and time 2. Mean arterial pressure (MAP) was measured at both time points via an automated BP machine. TPR was calculated as MAP divided by cardiac output. Results showed AAs to have higher BP and higher TPR at time 2 compared with EAs, independent of several important covariates. Also, higher HRV at time 1 significantly predicted both lower TPR and BP at time 2 among EAs only; these associations were attenuated and not significant in AAs. HRV did not significantly predict cardiac output at time 2 in the full sample or split by ethnicity. Our findings highlight that AAs show TPR mediated long-term increases in BP irrespective of resting HRV, providing a physiological pathway linking AAs with a greater risk for mortality and morbidity from hypertension and potentially other cardiovascular disease.NEW & NEWSWORTHY African Americans and European Americans differ in hemodynamics underlying long-term blood pressure regulation. Over 6 yr, African Americans show total peripheral resistance-mediated increases in blood pressure compared with European Americans. Higher heart rate variability predicts lower blood pressure and total peripheral resistance 6 yr later in European Americans but not African Americans.

Rapid decline of resting heart rate trajectories from childhood to young adulthood is paradoxically associated with increased cardiac mass.

BACKGROUND: Little is known about the varied resting heart rate (RHR) trajectory patterns from childhood to young adulthood and their clinical significance. We aim to identify RHR trajectories from childhood to young adulthood, and to determine their relationship with left ventricular mass (LVM) index. METHODS: RHR was measured up to 15 times over a 21-year period in 759 participants from childhood to young adulthood. LVM was measured using echocardiography and was normalised to body surface area to obtain LVM index in 546 participants. RESULTS: Using latent class models, three trajectory groups in RHR from childhood to young adulthood were identified, including high-decreasing group (HDG), moderate-decreasing group (MDG), and low-decreasing group (LDG). We found that trajectory of RHR was a significant predictor of LVM index with faster decrease of RHR associated with higher levels of total peripheral resistance (P for trend <0.001) and LVM index (P for trend <0.001). Compared to the LDG, individuals in the HDG showed higher LVM index (ß = 6.08, p < 0.001). In addition, the interactions between race and RHR trajectories for LVM index was significant (p < 0.05). CONCLUSION: Our findings show an association between RHR trajectories from childhood to young adulthood with cardiac mass, suggesting that monitoring RHR may help identify subpopulation at high cardiovascular risk.

Ethnic and sex differences in the longitudinal association between heart rate variability and blood pressure.

PURPOSE: Elevated blood pressure is a risk factor for increased cardiovascular morbidity and mortality. Decreased vagally-mediated heart rate variability has previously been prospectively linked with increased blood pressure; however, to date, no such prospective data exist regarding this relationship among Blacks. MATERIALS AND METHODS: We examined this association in 387 normotensive young adults (mean age, 23 years, 52% female, 54% Black) who participated in two laboratory evaluations spanning approximately six years. Blood pressure was measured at both timepoints with a non-invasive oscillometric device and heart rate variability was assessed via bio-impedance. RESULTS: In the total sample, heart rate variability significantly predicted systolic (p = .022) and diastolic (p < .001) blood pressure increases six years into the future. However, this pattern varied as a function of ethnicity and sex with the effect of heart rate variability on Time 2 systolic blood pressure only significant among White males (p = .007). Heart rate variability was also predictive of Time 2 diastolic blood pressure in White males (p = .038) as well as among both White (p = .032) and Black (p = .015) females, but was not related to blood pressure among Black males. CONCLUSION: We report for the first time significant ethnic and sex differences in the prospective relationship between heart rate variability and blood pressure change. These findings may give clues as to the underlying mechanisms that are involved in the well-known health disparities in blood pressure and hypertension-related cardiovascular diseases.

Effects of Race, Cardiac Mass, and Cardiac Load on Myocardial Function Trajectories from Childhood to Young Adulthood: The Augusta Heart Study.

Background The overall goal of this longitudinal study was to determine if the Black population has decreased myocardial function, which has the potential to lead to the early development of congestive heart failure, compared with the White population. Methods and Results A total of 673 subjects were evaluated over a period of 30 years including similar percentages of Black and White participants. Left ventricular systolic function was probed using the midwall fractional shortening (MFS). A longitudinal analysis of the MFS using a mixed effect growth curve model was performed. Black participants had greater body mass index, higher blood pressure readings, and greater left ventricular mass compared with White participants (all P<0.01). Black participants had a 0.54% decrease of MFS compared with White participants. As age increased by 1 year, MFS increased by 0.05%. As left ventricular mass increased by 1 g, MFS decreased by 0.01%. As circumferential end systolic stress increased by 1 unit, MFS decreased by 0.04%. The MFS trajectories for race differed from early age to young adulthood. Conclusions Changes in myocardial function mirror the race-dependent variations in blood pressure, afterload, and cardiac mass, suggesting that myocardial function depression occurs early in childhood in populations at high cardiovascular risk such as Black participants.

Association Between Enteral Feeding, Weight Status, and Mortality in a Medical Intensive Care Unit.

BACKGROUND: Clinical practice guidelines recommend enteral nutrition for most patients receiving mechanical ventilation. However, recently published evidence on the effect of enteral nutrition on mortality, particularly for patients who are well nourished, is conflicting. OBJECTIVES: To examine the association between enteral feeding and hospital mortality in critically ill patients receiving mechanical ventilation and to determine if body mass index mediates this relationship. METHODS: A retrospective cohort study of patients receiving mechanical ventilation admitted to a medical intensive care unit in 2013. Demographic and clinical variables were collected. Cox proportional hazards regression was used to examine the relationship between an enteral feeding order and hospital mortality and to determine if the relationship was mediated by body mass index. RESULTS: Of 777 patients who had 811 hospitalizations requiring mechanical ventilation, 182 (23.4%) died in the hospital. A total of 478 patients (61.5%) received an order for enteral tube feeding, which was associated with a lower risk of death (hazard ratio, 0.41; 95% CI, 0.29-0.59). Body mass index did not mediate the relationship between mortality and receipt of an order for enteral feeding. Median stay in the unit was 3.6 days. Most deaths (72.0%) occurred more than 48 hours after admission. CONCLUSION: The finding of a positive association between an order for enteral feeding and survival supports enteral feeding of patients in medical intensive care units. Furthermore, the beneficial effect of enteral feeding appears to apply to patients regardless of body mass index.

Use of standardized outcome measures in physical therapist practice: perceptions and applications.

BACKGROUND: Standardized instruments for measuring patients' activity limitations and participation restrictions have been advocated for use by rehabilitation professionals for many years. The available literature provides few recent reports of the use of these measures by physical therapists in the United States. OBJECTIVE: The primary purpose of this study was to determine: (1) the extent of the use of standardized outcome measures and (2) perceptions regarding their benefits and barriers to their use. A secondary purpose was to examine factors associated with their use among physical therapists in clinical practice. DESIGN: The study used an observational design. METHODS: A survey questionnaire comprising items regarding the use and perceived benefits and barriers of standardized outcome measures was sent to 1,000 randomly selected members of the American Physical Therapy Association (APTA). RESULTS: Forty-eight percent of participants used standardized outcome measures. The majority of participants (>90%) who used such measures believed that they enhanced communication with patients and helped direct the plan of care. The most frequently reported reasons for not using such measures included length of time for patients to complete them, length of time for clinicians to analyze the data, and difficulty for patients in completing them independently. Use of standardized outcome measures was related to specialty certification status, practice setting, and the age of the majority of patients treated. LIMITATIONS: The limitations included an unvalidated survey for data collection and a sample limited to APTA members. CONCLUSIONS: Despite more than a decade of development and testing of standardized outcome measures appropriate for various conditions and practice settings, physical therapists have some distance to go in implementing their use routinely in most clinical settings. Based on the perceived barriers, alterations in practice management strategies and the instruments themselves may be necessary to increase their use.