Blood pressure determinants of left ventricular wall thickness and mass index in hypertension: comparing office, ambulatory and exercise blood pressures

Exercise blood pressure, cardiorespiratory fitness, fatness and cardiovascular risk in children and adolescents

Cardiovascular disease remains the leading cause of mortality on a global scale. Individuals who possess risk factors for cardiovascular disease, such as high blood pressure (BP) and obesity, face an elevated risk of experiencing organ-specific pathophysiological changes. This damage includes pathophysiological changes in the heart and peripheral vascular systems, such as ventricular hypertrophy, arterial stiffening, and vascular narrowing and stenosis. Consequently, these damages are associated with an increased risk of developing severe cardiovascular outcomes including stroke, myocardial infarction, heart failure, and coronary heart disease. Among all the risk factors associated with cardiovascular disease, high blood pressure emerges as the most prominent. However, conventional resting BP measurement methods such as auscultatory or oscillometric methods may fail to identify many individuals with asymptomatic high BP. Recently, exercise BP has emerged as a valuable diagnostic tool for identifying real (high) blood pressure levels and assessing underlying cardiovascular risk, in addition to resting BP measurements in adults. Furthermore, numerous established factors, such as low cardiorespiratory fitness and high body fatness, have been confirmed to contribute to exercise BP and the associated cardiovascular risk. Modifying these factors may help reduce high exercise BP and, consequently, alleviate the burden of cardiovascular disease. A significant body of evidence has demonstrated cardiovascular disease in later life have their origins in early life. Children and adolescents with these cardiovascular risk factors also possess a greater propensity to develop cardiovascular diseases later in life. Nevertheless, the majority of previous studies on the clinical utility of exercise BP have been conducted in middle-to-older aged populations, often with pre-existing clinical conditions. Therefore, there is a need to investigate further of the factors influencing exercise BP in adolescence and its association with cardiovascular risk in early life. Our previously published work showed that exercise BP is a potential useful method to detect adolescents with increased cardiovascular risk. Children and adolescents with cardiovascular risk factors are more likely to develop cardiovascular diseases later in life. However, previous studies on the clinical utility of exercise BP have largely focused on middle-to-older aged populations with pre-existing clinical conditions. Therefore, there is a need to investigate further the factors influencing exercise BP in adolescence and its association with future cardiovascular risk. Our previous studies, which focused on exercise BP measured at submaximal intensity, have shown that exercise BP is a potentially useful method for identifying adolescents at increased cardiovascular risk. Our previous findings suggest that improving cardio-respiratory fitness and reducing body fatness may help to reduce the risk of developing cardiovascular disease and improve overall cardiovascular health. These findings have important implications for the development of effective prevention and early detection strategies, which can contribute to improved public health outcomes.

Inverse Association between Exercising Blood Pressure Response and Left Ventricular Chamber Size and Mass in Women Who Habitually Resistance Train

Exercise is a major modifiable lifestyle factor that leads to temporarily increased systolic blood pressure (SBP), which is thought to influence left ventricular mass normalized to body surface area (LVM/BSA). This relationship has never been studied in women who habitually perform resistance exercise.

PURPOSE

To determine if a direct correlation exists between the SBP response to resistance exercise (change from rest; eSBP) and LVM/BSA in young healthy women who habitually resistance train.

METHODS

Leg extension resistance exercise was performed while continuously monitoring blood pressure using finger plethysmography. LVM was estimated using echocardiography. Data are shown as mean ± SD.

RESULTS

Thirty-one women participated (age 23 ± 3 years, height 164 ± 7 cm, body mass 63.7 ± 10.3 kg). Resting SBP (110 ± 8 mmHg, r = 0.355, p = 0.049) was shown to be directly correlated to LVM/BSA (72.0 ± 28.4 g/m2). Conversely, eSBP (30.8 ± 14.6 ∆mmHg, r = -0.437, p = 0.014) was inversely related to LVM/BSA. eSBP was not correlated to interventricular septum width (0.88 ± 0.12 cm, r = -0.137, p = 0.463) or posterior wall thickness (0.91 ± 0.15 cm, r = -0.084, p = 0.654). eSBP was inversely related to left ventricle internal diameter during diastole (LVIDd) (4.25 ± 0.33 cm, r = -0.411, p = 0.021).

CONCLUSION

Counter to the hypothesis, these data suggest an inverse association between eSBP during resistance exercise and LVM/BSA in healthy young women who resistance train. This relationship is due to a smaller LVIDd with greater eSBP.

Blood Pressure Responses During Exercise: Physiological Correlates and Clinical Implications

BACKGROUND

Abnormal blood pressure (BP) responses to exercise can predict adverse cardiovascular outcomes, but their optimal measurement and definitions are poorly understood. We combined frequently sampled BP during cardiopulmonary exercise testing with vascular stiffness assessment to parse cardiac and vascular components of exercise BP.

METHODS

Cardiopulmonary exercise testing with BP measured every two minutes and resting vascular tonometry were performed in 2858 Framingham Heart Study participants. Linear regression was used to analyze sex-specific exercise BP patterns as a function of arterial stiffness (carotid-femoral pulse wave velocity) and cardiac-peripheral performance (defined by peak O2 pulse).

RESULTS

Our sample was balanced by sex (52% women) with mean age 54±9 years and 47% with hypertension. We observed variability in carotid-femoral pulse wave velocity and peak O2 pulse across individuals with clinically defined exercise hypertension (peak systolic BP [SBP] in men ≥210 mm Hg; in women ≥190 mm Hg). Despite similar resting SBP and cardiometabolic profiles, individuals with higher peak O2 pulse displayed higher peak SBP (P≤0.017) alongside higher fitness levels (P<0.001), suggesting that high peak exercise SBP in the context of high peak O2 pulse may in fact be favorable. Although both higher (favorable) O2 pulse and higher (adverse) arterial stiffness were associated with greater peak SBP (P<0.0001 for both), the magnitude of association of carotid-femoral pulse wave velocity with peak SBP was higher in women (sex-carotid-femoral pulse wave velocity interaction P<0.0001). In sex-specific models, exercise SBP measures accounting for workload (eg, SBP during unloaded exercise, SBP at 75 watts, and SBP/workload slope) were directly associated with the adverse features of greater arterial stiffness and lower peak O2 pulse.

CONCLUSIONS

Higher peak exercise SBP reflects a complex trade-off between arterial stiffness and cardiac-peripheral performance that differs by sex. Studies of BP responses to exercise accounting for vascular and cardiac physiology may illuminate mechanisms of hypertension and clarify clinical interpretation of exercise BP.

Immunosuppression of Macrophages Underlies the Cardioprotective Effects of CST (Catestatin)

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High Salt Intake Augments Blood Pressure Responses During Submaximal Aerobic Exercise

Background High sodium (Na+) intake is a widespread cardiovascular disease risk factor. High Na+ intake impairs endothelial function and exaggerates sympathetic reflexes, which may augment exercising blood pressure (BP) responses. Therefore, this study examined the influence of high dietary Na+ on BP responses during submaximal aerobic exercise. Methods and Results Twenty adults (8F/12M, age=24±4 years; body mass index 23.0±0.6 kg·m-2; VO2peak=39.7±9.8 mL·min-1·kg-1; systolic BP=111±10 mm Hg; diastolic BP=64±8 mm Hg) participated in this randomized, double-blind, placebo-controlled crossover study. Total Na+ intake was manipulated via ingestion of capsules containing either a placebo (dextrose) or table salt (3900 mg Na+/day) for 10 days each, separated by ≥2 weeks. On day 10 of each intervention, endothelial function was assessed via flow-mediated dilation followed by BP measurement at rest and during 50 minutes of cycling at 60% VO2peak. Throughout exercise, BP was assessed continuously via finger photoplethysmography and every 5 minutes via auscultation. Venous blood samples were collected at rest and during the final 10 minutes of exercise for assessment of norepinephrine. High Na+ intake increased urinary Na+ excretion (placebo=140±68 versus Na+=282±70 mmol·24H-1; P<0.001) and reduced flow-mediated dilation (placebo=7.2±2.4 versus Na+=4.2±1.7%; P<0.001). Average exercising systolic BP was augmented following high Na+ (placebo=Δ30.0±16.3 versus Na+=Δ38.3±16.2 mm Hg; P=0.03) and correlated to the reduction in flow-mediated dilation (R=-0.71, P=0.002). Resting norepinephrine concentration was not different between conditions (P=0.82). Norepinephrine increased during exercise (P=0.002), but there was no Na+ effect (P=0.26). Conclusions High dietary Na+ augments BP responses during submaximal aerobic exercise, which may be mediated, in part, by impaired endothelial function.

An exaggerated blood pressure response to exercise is associated with nitric oxide bioavailability and inflammatory markers in normotensive females

This study was designed to examine the associations of an exaggerated systolic blood pressure (SBP) response to exercise with the indices of nitric oxide (NO) bioavailability, oxidative stress, inflammation and arterial stiffness in normotensive females. The subjects included 84 normotensive females without a history of cardiovascular disease or stroke who were not taking any medications. Each subject performed a multistage graded submaximal exercise stress test using an electric bicycle ergometer, and their blood pressure was measured at rest and during the last minute of each stage. The brachial-ankle pulse wave velocity, plasma nitrate/nitrite (NO_x), plasma thiobarbituric acid-reactive substances, high-sensitivity C-reactive protein (hs-CRP) and fibrinogen levels and the white blood cell count were measured. An exaggerated SBP response to exercise was defined according to the criteria of the Framingham Study (peak SBP: ⩾190 mm Hg). An exaggerated SBP response to exercise was observed in 27 subjects. A multiple logistic regression analysis revealed that the hs-CRP (odds ratio (OR): 1.05, 95% confidence interval (CI): 1.03-1.07, P=0.015) and plasma NO_x levels (OR: 0.92, 95% CI: 0.87-0.98, P=0.014) were significantly associated with an exaggerated SBP response to exercise. Furthermore, the percent change in SBP was found to be significantly associated with an increase in the hs-CRP (P for trend=0.006) and a decrease in the plasma NO_x levels (P for trend=0.001). These results suggest that an exaggerated SBP response to exercise was associated with the NO bioavailability and inflammatory status in normotensive females.

High dietary phosphate intake induces hypertension and augments exercise pressor reflex function in rats

An increasing number of studies have linked high dietary phosphate (Pi) intake to hypertension. It is well established that the rise in sympathetic nerve activity (SNA) and blood pressure (BP) during physical exertion is exaggerated in many forms of hypertension, which are primarily mediated by an overactive skeletal muscle exercise pressor reflex (EPR). However, it remains unknown whether high dietary Pi intake potentiates the EPR-mediated SNA and BP response to exercise. Accordingly, we measured renal SNA (RSNA) and mean BP (MBP) in normotensive Sprague-Dawley rats fed a normal Pi diet (0.6%, n = 13) or high Pi diet (1.2%, n = 13) for 3 mo. As previously reported, we found that resting BP was significantly increased by 1.2% Pi diet in both conscious and anesthetized animals. Activation of the EPR by electrically induced hindlimb contraction triggered greater increases in ΔRSNA and ΔMBP in the 1.2% compared with 0.6% Pi group (126 ± 25 vs. 42 ± 9%; 44 ± 5 vs. 14 ± 2 mmHg, respectively, P < 0.01). Activation of the muscle mechanoreflex, a component of the EPR, by passively stretching hindlimb muscle also evoked greater increases in ΔRSNA and ΔMBP in the 1.2% compared with 0.6% Pi group (109 ± 27 vs. 24 ± 7%, 38 ± 7 vs. 8 ± 2 mmHg, respectively, P < 0.01). A similar response was produced by hindlimb intra-arterial capsaicin administration to stimulate the metaboreflex arm of the EPR. Thus, our data demonstrate a novel action of dietary Pi loading in augmenting EPR function through overactivation of both the muscle mechanoreflex and metaboreflex.

Aldosterone and Salt Loading Independently Exacerbate the Exercise Pressor Reflex in Rats

The sympathetic and pressor responses to exercise are exaggerated in hypertension. Evidence suggests that an overactive exercise pressor reflex (EPR) contributes to this abnormal responsiveness. The mechanisms underlying this EPR overactivity are poorly understood. An increasing body of evidence suggests that aldosterone and excessive salt intake play a role in regulating resting sympathetic activity and blood pressure in hypertension. Therefore, each is a good candidate for the generation of EPR dysfunction in this disease. The purpose of this study was to examine whether excessive salt intake and chronic administration of aldosterone potentiate EPR function. Changes in mean arterial pressure and renal sympathetic nerve activity induced by EPR stimulation were examined in vehicle and aldosterone-treated (4 weeks via osmotic mini-pump) Sprague-Dawley rats given either water or saline (elevated salt load) to drink. When compared with vehicle/water-treated rats, stimulation of the EPR by muscle contraction evoked significantly greater increases in mean arterial pressure in vehicle/saline, aldosterone/water, and aldosterone/saline-treated animals (14±3, 29±3, 37±6, and 44±7 mm Hg/kg, respectively; P<0.01). A similar renal sympathetic nerve activity response profile was likewise produced (39±11%, 87±15%, 110±20%, and 151±25%/kg, respectively; P<0.01). The pressor and sympathetic responses to the individual activation of the mechanically and chemically sensitive components of the EPR were also augmented by both saline and aldosterone. These data provide the first direct evidence that both aldosterone and high salt intake elicit EPR overactivity. As such, each represents a potential mechanism by which sympathetic activity and blood pressure are augmented during exercise in hypertension.

Dynamic exercise training prevents exercise pressor reflex overactivity in spontaneously hypertensive rats

Cardiovascular responses to exercise are exaggerated in hypertension. We previously demonstrated that this heightened cardiovascular response to exercise is mediated by an abnormal skeletal muscle exercise pressor reflex (EPR) with important contributions from its mechanically and chemically sensitive components. Exercise training attenuates exercise pressor reflex function in healthy subjects as well as in heart failure rats. However, whether exercise training has similar physiological benefits in hypertension remains to be elucidated. Thus we tested the hypothesis that the EPR overactivity manifest in hypertension is mitigated by exercise training. Changes in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) in response to muscle contraction, passive muscle stretch, and hindlimb intra-arterial capsaicin administration were examined in untrained normotensive Wistar-Kyoto rats (WKYUT; n = 6), exercise-trained WKY (WKYET; n = 7), untrained spontaneously hypertensive rats (SHRUT; n = 8), and exercise-trained SHR (SHRET; n = 7). Baseline MAP after decerebration was significantly decreased by 3 mo of wheel running in SHRET (104 ± 9 mmHg) compared with SHRUT (125 ± 10 mmHg). As previously reported, the pressor and renal sympathetic responses to muscle contraction, stretch, and capsaicin administration were significantly higher in SHRUT than WKYUT. Exercise training significantly attenuated the enhanced contraction-induced elevations in MAP (SHRUT: 53 ± 11 mmHg; SHRET: 19 ± 3 mmHg) and RSNA (SHRUT: 145 ± 32%; SHRET: 57 ± 11%). Training produced similar attenuating effects in SHR during passive stretch and capsaicin administration. These data demonstrate that the abnormally exaggerated EPR function that develops in hypertensive rats is significantly diminished by exercise training.

Relations of exercise blood pressure response to cardiovascular risk factors and vascular function in the Framingham Heart Study

BACKGROUND

Exercise blood pressure (BP) is an important marker of left ventricular hypertrophy, incident hypertension, and future cardiovascular events. Although impaired vascular function is hypothesized to influence the BP response during exercise, limited data exist on the association of vascular function with exercise BP in the community.

METHODS AND RESULTS

Framingham Offspring cohort participants (n=2115, 53% women, mean age 59 years) underwent a submaximal exercise test (first 2 stages of the Bruce protocol), applanation tonometry, and brachial artery flow-mediated dilation testing. We related exercise systolic and diastolic BP at second stage of the Bruce protocol to standard cardiovascular risk factors and to vascular function measures. In multivariable linear regression models, exercise systolic BP was positively related to age, standing BP, standing heart rate, smoking, body mass index, and the total cholesterol-to-high-density cholesterol ratio (P≤0.01 for all). Similar associations were observed for exercise diastolic BP. Carotid-femoral pulse wave velocity (P=0.02), central pulse pressure (P<0.0001), mean arterial pressure (P=0.04), and baseline brachial flow (P=0.002) were positively associated with exercise systolic BP, whereas flow-mediated dilation was negatively associated (P<0.001). For exercise diastolic BP, forward pressure wave amplitude was negatively related (P<0.0001), whereas mean arterial pressure was positively related (P<0.0001).

CONCLUSIONS

Increased arterial stiffness and impaired endothelial function are significant correlates of a higher exercise systolic BP response. Our findings suggest that impaired vascular function may contribute to exaggerated BP responses during daily living, resulting in repetitive increments in load on the heart and vessels and increased cardiovascular disease risk.

The role of mood disorders in exercise-induced cardiovascular reactivity

OBJECTIVE

Increased cardiovascular (CV) reactivity has been associated with worse CV prognosis. Though mood disorders (MDs) have been associated with increased CV reactivity during behavioral stressors, the extent to which MDs and their interaction with coronary heart disease (CHD) influences exercise-induced CV reactivity has not been evaluated.

METHODS

Five hundred twenty-six patients underwent nuclear exercise stress testing. Cardiovascular parameters were assessed at rest, every 2 minutes during exercise, and at peak exercise. MDs were measured using a structured psychiatric interview, the Primary Care Evaluation of Mental Disorders, and CHD was defined as having a history of myocardial infarction, revascularization, heart failure, and/or cerebrovascular event.

RESULTS

CHD patients exhibited lower peak exercise heart rate (F = 9.40, p = .002) compared with patients without CHD. Submaximal data showed that patients with CHD had a slower rate of increase of heart rate (F = 4.29, p = .04) and diastolic blood pressure (F = 3.27, p = .04). There was an interaction of CHD and MDs, indicating that in patients with CHD, the rate of submaximal increase in systolic blood pressure (F = 3.08, p = .047) and rate-pressure product (F = 5.13, p = .006) was greater in patients with a MD compared with those without a MD. These differences were not observed in patients with no CHD. No other main or interaction effects of MDs and CHD were observed.

CONCLUSION

Though MDs alone do not seem to be associated with higher levels of stress CV reactivity, their combination with CHD leads to increased submaximal exercise-induced CV reactivity. Prospective studies are needed to explore the causal relationship between these variables.

Exercise blood pressure response, albuminuria, and arterial stiffness in hypertension

BACKGROUND

A hypertensive response to exercise is associated with high cardiovascular risk, whereas the data about its relation to surrogates of subclinical atherosclerosis are scarce. We investigated the relationships of a hypertensive response to exercise with urinary albumin excretion and arterial stiffness in hypertensives.

METHODS

There were 171 untreated males (mean age 52 years, all Caucasian) with stage I-II essential hypertension and a negative treadmill exercise test divided into those with a hypertensive response to exercise (n=48) (peak exercise systolic blood pressure > or =210 mm Hg) and to those with normal blood pressure response (n=123). Albumin-to-creatinine ratio values were determined as the mean of 3 nonconsecutive morning spot urine samples, and arterial stiffness was evaluated on the basis of carotid-to-femoral pulse wave velocity.

RESULTS

Patients with a hypertensive response to exercise compared with those with normal blood pressure response exhibited greater log albumin-to-creatinine ratio (1.52+/-0.59 vs 0.97+/-0.33 mg/g) and higher pulse wave velocity (8.7+/-1.6 vs 7.7+/-1.2 m/s), independent of potentially confounding demographic and clinical factors. Resting systolic blood pressure (odds ratio [OR] 1.11, 95% confidence interval [CI], 1.06-1.16), body mass index (OR 1.12, 95% CI, 1.02-1.23), resting heart rate (OR 0.96, 95% CI, 0.93-0.99), and albumin-to-creatinine ratio (OR 7.45, 95% CI, 2.54-21.83) were independently associated with a hypertensive response to exercise.

CONCLUSION

A hypertensive response to exercise is related to augmented albumin-to-creatinine ratio and arterial stiffness, reflecting accelerated subclinical atherosclerosis. The association of albumin excretion with exercise blood pressure response suggests that albuminuria constitutes an important factor in the interpretation of the hypertensive response to exercise-associated risk.

Exercise blood pressure, cardiac structure, and diastolic function in young normotensive patients with polycystic kidney disease: a prehypertensive state

BACKGROUND

Increased left ventricular mass (LVM) and left ventricular hypertrophy have been found in early stages of autosomal dominant polycystic kidney disease (ADPKD). The mechanisms that lead to an increase in LVM in this population are unknown. The aim of this study is to evaluate blood pressure (BP) response to exercise and very early alterations in cardiac structure and diastolic function in young normotensive patients with ADPKD.

METHODS

Color Doppler echocardiography and exercise treadmill testing according to the Bruce protocol were performed in 18 young normotensive patients with ADPKD and 18 healthy subjects.

RESULTS

LVM index was greater and isovolumic relaxation time (IVRT) was longer in patients with ADPKD than controls (93.3 +/- 21.4 versus 77.5 +/- 18.6 g/m2; P = 0.02; 100 +/- 20.2 versus 80 +/- 9.7 milliseconds; P = 0.001, respectively). Exercise capacity in metabolic equivalents was similar in both groups. Systolic BP response during exercise and recovery were similar in both groups. Diastolic BP decreased during exercise, but the magnitude of decrease was lower in patients with ADPKD than controls (P = 0.01). During recovery, patients with ADPKD showed a greater sustained diastolic BP than controls (P = 0.02). Patients with ADPKD with an exaggerated systolic BP response had a greater LVM index than those with a normal response (112.1 +/- 10.4 versus 84 +/- 19.2 g/m2; P = 0.001). Multivariate regression analysis showed that exercise systolic BP and diastolic BP were independent predictors of LVM index and IVRT, respectively.

CONCLUSION

Young normotensive patients with ADPKD showed increased LVM index and prolonged IVRT, which are related to exercise BP response. Exaggerated diastolic BP response during exercise suggests an impaired capacity for exercise-induced vasodilatation and may indicate a greater risk for the development of future hypertension.

Relationship between exercise systolic blood pressure and left ventricular geometry in overweight, mildly hypertensive patients

OBJECTIVE

To examine the association between the graded exercise systolic blood pressure (SBP) response and left ventricular (LV) geometric structure in patients with untreated mild hypertension.

PARTICIPANTS

The study included 80 sedentary, overweight patients (43 female and 37 male) with unmedicated high normal blood pressure or stage 1-2 hypertension.

METHODS

An echocardiogram was used to determine LV mass and the relative wall thickness (RWT) in relation to the chamber dimension. Participants performed a maximal graded exercise test, and the SBP was recorded at workloads of 2, 4 and 6 metabolic equivalents and at peak exercise. Separate statistical models were used to determine the influence of LV mass indexed for height(2.7) (LVMIh) and RWT on submaximal exercise SBP and peak exercise SBP, controlling for resting SBP, age, gender, ethnicity and body mass index.

RESULTS

A greater RWT was associated with a higher submaximal SBP level (P = 0.038). Neither LVMIh (P = 0.989) nor the interaction of RWT and LVMIh (P = 0.787) were related to the submaximal SBP. None of the main or interaction effects of RWT and LVMIh were associated with the peak exercise SBP level.

CONCLUSION

Increases in RWT were associated with higher submaximal exercise SBP responses in a sample of overweight, unmedicated hypertensives. These results suggest that RWT is an important determinant of the association between cardiac mass and exercise SBP response.