Baroreflex stabilization of the double product

Prognostic Value of Nighttime Double Product in Nondialysis Chronic Kidney Disease With Hypertension

BACKGROUND

Both nighttime systolic blood pressure and pulse rate are associated with adverse outcomes in patients with chronic kidney disease (CKD). However, nighttime double product (DP), which is the product of nighttime systolic blood pressure and pulse rate, has not yet been investigated in this context. The present study aimed to explore the prognostic value of nighttime DP for adverse outcomes in patients with CKD and hypertension.

METHODS AND RESULTS

This retrospective cohort study included a total of 1434 patients with nondialysis CKD complicated by hypertension. The patients were enrolled in Zhuhai and Guangzhou, China, with a median follow-up of 23.8 months. Patient enrollment for the high or low nighttime DP group was performed on the basis of the cutoff value determined by time-dependent receiver operator characteristic curve analysis. The primary end point was a composite of major cardiovascular and cerebrovascular events, and the secondary end point was all-cause death and composite renal end point. The 24-hour circadian DP rhythm was established via multiple-component cosinor analysis. Cox regression was used to explore the association between nighttime DP and adverse outcomes. The DP of nondialysis patients with CKD and hypertension showed a diurnal rhythm, which varied with renal function. After adjustment, high nighttime DP was associated with a higher risk for major cardiovascular and cerebrovascular events (hazard ratio [HR], 5.823 [95% CI, 2.382-14.233]), all-cause death (HR, 4.978 [95% CI, 2.205-11.240]), and composite renal event (HR, 1.661 [95% CI, 1.128-2.447]), compared with low nighttime DP. These associations were independent of nighttime systolic blood pressure and PR.

CONCLUSIONS

The present cohort study demonstrated that DP had diurnal fluctuations and nighttime DP was an important prognostic factor in nondialysis patients with CKD and hypertension, outperforming traditional risk factors, including systolic blood pressure and pulse rate.

Chronic Red Bull Consumption during Adolescence: Effect on Mesocortical and Mesolimbic Dopamine Transmission and Cardiovascular System in Adult Rats

Energy drinks are very popular nonalcoholic beverages among adolescents and young adults for their stimulant effects. Our study aimed to investigate the effect of repeated intraoral Red Bull (RB) infusion on dopamine transmission in the nucleus accumbens shell and core and in the medial prefrontal cortex and on cardiac contractility in adult rats exposed to chronic RB consumption. Rats were subjected to 4 weeks of RB voluntary consumption from adolescence to adulthood. Monitoring of in vivo dopamine was carried out by brain microdialysis. In vitro cardiac contractility was studied on biomechanical properties of isolated left-ventricular papillary muscle. The main finding of the study was that, in treated animals, RB increased shell dopamine via a nonadaptive mechanism, a pattern similar to that of drugs of abuse. No changes in isometric and isotonic mechanical parameters were associated with chronic RB consumption. However, a prolonged time to peak tension and half-time of relaxation and a slower peak rate of tension fall were observed in RB-treated rats. It is likely that RB treatment affects left-ventricular papillary muscle contraction. The neurochemical results here obtained can explain the addictive properties of RB, while the cardiovascular investigation findings suggest a hidden papillary contractility impairment.

Continuous Hemodynamic Monitoring in an Intact Rat Model of Simulated Diving

Cardiovascular risk is elevated in divers, but detailed information of cardiac function during diving is missing. The aim of this study was to apply an intact rat model with continuous monitoring of cardiac left ventricular (LV) function in a simulated diving experiment. Thirteen rats were inserted with a LV pressure-volume catheter and a pressure transducer in the femoral artery to measure hemodynamic variables, and randomly assigned to diving (n = 9) and control (n = 4) groups. The diving group was compressed to 600 kPa in air, maintained at pressure for 45 min (bottom phase), and decompressed to surface at 50 kPa/min. Data was collected before, during, and up to 60 min after exposure in the diving group, and at similar times in non-diving controls. During the bottom phase, stroke volume (SV) (-29%) and cardiac output (-30%) decreased, whereas LV end-systolic volume (+13%), mean arterial pressure (MAP) (+29%), and total peripheral resistance (TPR) (+72%) increased. There were no changes in LV contractility, stroke work, or diastolic function. All hemodynamic variables returned to baseline values within 60 min after diving. In conclusion, our simulated dive experiment to 600 kPa increased MAP and TPR to levels which caused a substantial reduction in SV and LV volume output. The increase in cardiac afterload demonstrated to take place during a dive is well tolerated by the healthy heart in our model, whereas in a failing heart this abrupt change in afterload may lead to acute cardiac decompensation.

Cardiovascular and Orthostatic Responses to a Festive Meal Associated With Alcohol in Young Men

Aim: Sharing a festive meal associated with alcohol is quite common. While the cardiovascular changes occurring after meal ingestion of different nutrient composition has been well-established, the effects of ingesting a festive versus a standard meal accompanied with alcohol are less clear. Here, we compared the postprandial hemodynamics, cutaneous and psychomotor performance responses after ingestion of a classical Swiss festive meal [cheese fondue (CF)] versus a light ready-meal [Nasi Goreng (NG)], both accompanied with white wine.

Methods: In a randomized cross over design, we examined in 12 healthy young men, the continuous cardiovascular, cutaneous, and reaction time responses to ingestion of cheese fondue versus a standard meal at rest (sitting position) and hemodynamic changes in response to orthostatic challenge (active standing) in pre- and postprandial phases.

Results: Breath alcohol concentration after wine ingestion was similar after both meal types. Compared to the standard meal, consumption of CF induced higher increases in heart rate (HR), cardiac output (CO), double product (DP) and cardiac power output (CPO), greater vasodilation, and rises in skin blood flow and skin temperature. Greater increases in HR, DP, and mean blood pressure (MBP) were observed during orthostatic challenges with CF compared to NG. A two-choice reaction time task revealed similar reaction times with both meals, suggesting no influence of meal composition on psychomotor performance.

Conclusion: In sitting position, CF ingestion induced a more important cardiovascular load compared to NG. Although the dose of alcohol and the festive meal used here did not lead to orthostatic hypotension, eating CF induced a greater cardiometabolic load suggesting that hemodynamic reserves have been encroached during active standing. This may impede the cardiovascular capacity during physical exercise or stress situations, particularly in elderly subjects who are at greater risk for postprandial hypotension and cardiovascular diseases.

Early and Late Cardiovascular and Metabolic Responses to Mixed Wine: Effect of Drink Temperature

Aim: Red wine is usually ingested as an unmixed drink. However, mixtures of wine with juices and/or sucrose (mixed wine) are becoming more and more popular and could be ingested at either cold or hot temperature. Although the temperature effects on the cardiovascular system have been described for water and tea, with greater energy expenditure (EE) and lower cardiac workload with a colder drink, little information is available on the impact of temperature of alcoholic beverages on alcoholemia and cardiometabolic parameters. The purpose of the present study was to compare the acute cardiovascular and metabolic changes in response to mixed wine ingested at a cold or at a hot temperature.

Methods: In a randomized crossover design, 14 healthy young adults (seven men and seven women) were assigned to cold or hot mixed wine ingestion. Continuous cardiovascular, metabolic, and cutaneous monitoring was performed in a comfortable sitting position during a 30-min baseline and for 120 min after ingesting 400 ml of mixed wine, with the alcohol content adjusted to provide 0.4 g ethanol/kg of body weight and drunk at either cold (3°C) or hot (55°C) temperature. Breath alcohol concentration was measured intermittently throughout the study.

Results: Overall, alcoholemia was not altered by drink temperature, with a tendency toward greater values in women compared to men. Early responses to mixed wine ingestion (0–20 min) indicated that cold drink transiently increased mean blood pressure (BP), cardiac vagal tone, and decreased skin blood flow (SkBf) whereas hot drink did not change BP, decreased vagal tone, and increased SkBf. Both cold and hot mixed wine led to increases in EE and reductions in respiratory quotient. Late responses (60–120 min) led to similar cardiovascular and metabolic changes at both drink temperatures.

Conclusion: The magnitude and/or the directional change of most of the study variables differed during the first 20 min following ingestion and may be related to drink temperature. By contrast, late changes in cardiometabolic outcomes were similar between cold and hot wine ingestion, underlying the typical effect of alcohol and sugar intake on the cardiovascular system.

Cardiovascular and Metabolic Responses to the Ingestion of Caffeinated Herbal Tea: Drink It Hot or Cold?

Aim: Tea is usually consumed at two temperatures (as hot tea or as iced tea). However, the importance of drink temperature on the cardiovascular system and on metabolism has not been thoroughly investigated. The purpose of this study was to compare the cardiovascular, metabolic and cutaneous responses to the ingestion of caffeinated herbal tea (Yerba Mate) at cold or hot temperature in healthy young subjects. We hypothesized that ingestion of cold tea induces a higher increase in energy expenditure than hot tea without eliciting any negative effects on the cardiovascular system.

Methods: Cardiovascular, metabolic and cutaneous responses were analyzed in 23 healthy subjects (12 men and 11 women) sitting comfortably during a 30-min baseline and 90 min following the ingestion of 500 mL of an unsweetened Yerba Mate tea ingested over 5 min either at cold (~3°C) or hot (~55°C) temperature, according to a randomized cross-over design.

Results: Averaged over the 90 min post-drink ingestion and compared to hot tea, cold tea induced (1) a decrease in heart rate (cold tea: −5 ± 1 beats.min⁻¹; hot tea: −1 ± 1 beats.min⁻¹, p < 0.05), double product, skin blood flow and hand temperature and (2) an increase in baroreflex sensitivity, fat oxidation and energy expenditure (cold tea: +8.3%; hot tea: +3.7%, p < 0.05). Averaged over the 90 min post-drink ingestion, we observed no differences of tea temperature on cardiac output work and mean blood pressure responses.

Conclusion: Ingestion of an unsweetened caffeinated herbal tea at cold temperature induced a greater stimulation of thermogenesis and fat oxidation than hot tea while decreasing cardiac load as suggested by the decrease in the double product. Further experiments are needed to evaluate the clinical impact of unsweetened caffeinated herbal tea at a cold temperature for weight control.

Cardiovascular and Cutaneous Responses to the Combination of Alcohol and Soft Drinks: The Way to Orthostatic Intolerance?

Aim: Acute ingestion of alcohol is often accompanied by cardiovascular dysregulation, malaise and even syncope. The full hemodynamic and cutaneous responses to the combination of alcohol and sugar (i.e., alcopops), a common combination in young people, and the mechanisms for the propensity to orthostatic intolerance are not well established. Thus, the purpose of this study was to evaluate the cardiovascular and cutaneous responses to alcopops in young subjects. Methods: Cardiovascular and cutaneous responses were assessed in 24 healthy young subjects (12 men, 12 women) sitting comfortably and during prolonged active standing with a 30-min baseline and 130 min following ingestion of 400 mL of either: water, water + 48 g sugar, water + vodka (1.28 mL.kg^-1 of body weight, providing 0.4 g alcohol.kg^-1), water + sugar + vodka, according to a randomized cross-over design. Results: Compared to alcohol alone, vodka + sugar induced a lower breath alcohol concentration (BrAC), blood pressure and total peripheral resistance (p < 0.05), a higher cardiac output and heart rate (p < 0.05) both in sitting position and during active standing. In sitting position vodka + sugar consumption also led to a greater increase in skin blood flow and hand temperature (p < 0.05) and a decrease in baroreflex sensitivity (p < 0.05). We observed similar results between men and women both in sitting position and during active standing. Conclusion: Despite lower BrAC, ingestion of alcopops induced acute vasodilation and hypotension in sitting position and an encroach of the hemodynamic reserve during active standing. Even if subjects did not feel any signs of syncope these results could be of clinical importance with higher doses of alcohol or if combined to other hypotensive challenges.

Water ingestion decreases cardiac workload time-dependent in healthy adults with no effect of gender

Ingestion of water entails a variety of cardiovascular responses. However, the precise effect remains elusive. We aimed to determine in healthy adults the effect of water on cardiac workload and to investigate potential gender differences. We pooled data from two controlled studies where blood pressure (BP) and heart rate (HR) were continuously recorded before and after the ingestion of 355 mL of tap water. Additionally, we calculated double product by multiplying systolic BP with HR and evaluated spectral parameters referring to vagal tone. All parameters were investigated for potential differences based on gender. In response to water, HR, systolic BP, and double product decreased significantly during the first 30 min. However, these effects were attenuated for HR and double product and even abolished for systolic BP over the subsequent 30 min. Over the entire post-drink period (60 min), decreases in HR and double product (all P < 0.05) were observed. Spectral markers for vagal tone increased with the on-set of the water drink and remained elevated until the end (P < 0.005). No significant gender difference in cardiac workload parameters was observed. We provide evidence that drinking water decreases, in a time-dependent fashion, cardiac workload and that these responses appear not to be influenced by gender.

Substantial Inter-Subject Variability in Blood Pressure Responses to Glucose in a Healthy, Non-obese Population

Aim: A large inter-subject variability in the blood pressure (BP) response to glucose drinks has been reported. However, the underlying factors remain elusive and we hypothesized that accompanying changes in glucose metabolism affect these BP responses.

Methods: Cardiovascular and glycemic changes in response to a standard 75 g oral-glucose-tolerance-test were investigated in 30 healthy, non-obese males. Continuous cardiovascular monitoring, including beat-to-beat BP, electrocardiographically deduced heart rate and impedance cardiography, was performed during a 30 min baseline and continued up to 120 min after glucose ingestion. Blood samples were taken at baseline, 30, 60, 90, and 120 min for the assessment of glucose, insulin and c-peptide. Additionally, we evaluated body composition by using validated bioelectrical impedance techniques.

Results: Individual overall changes (i.e., averages over 120 min) for systolic BP ranged from −4.9 to +4.7 mmHg, where increases and decreases were equally distributed (50%). Peak changes (i.e., peak averages over 10 min intervals) for systolic BP ranged from −1.3 to +9.5 mmHg, where 93% of subjects increased systolic BP above baseline values (similar for diastolic BP) whilst 63% of subjects increased peak systolic BP by more than 4 mmHg. Changes in peak systolic BP were negatively associated with the calculated Matsuda-index of insulin sensitivity (r = −0.39, p = 0.04) but with no other evaluated parameter including body composition. Moreover, besides a trend toward an association between overall changes in systolic BP and total fat mass percentage (r = +0.32, p = 0.09), no association was found between other body composition parameters and overall BP changes.

Conclusion: Substantial inter-subject variability in BP changes was observed in a healthy, non-obese subpopulation in response to an oral glucose load. In 63% of subjects, peak systolic BP increased by more than a clinically relevant 4 mmHg. Peak systolic BP changes, but not overall BP changes, correlated with insulin sensitivity, with little influence of body composition.

The blood pressure-elevating effect of Red Bull energy drink is mimicked by caffeine but through different hemodynamic pathways

The energy drink Red Bull (RB) has recently been shown to elevate resting blood pressure (BP) and double product (reflecting increased myocardial load). However, the extent to which these effects can be explained by the drink's caffeine and sugar content remains to be determined. We compared the cardiovascular impact of RB to those of a comparable amount of caffeine, and its sugar-free version in eight young healthy men. Participants attended four experimental sessions on separate days according to a placebo-controlled randomized crossover study design. Beat-to-beat hemodynamic measurements were made continuously for 30 min at baseline and for 2 h following ingestion of 355 mL of either (1) RB + placebo; (2) sugar-free RB + placebo; (3) water + 120 mg caffeine, or (4) water + placebo. RB, sugar-free RB, and water + caffeine increased BP equally (3-4 mmHg) in comparison to water + placebo (P < 0.001). RB increased heart rate, stroke volume, cardiac output, double product, and cardiac contractility, but decreased total peripheral resistance (TPR) (all P < 0.01), with no such changes observed following the other interventions. Conversely, sugar-free RB and water + caffeine both increased TPR in comparison to the water + placebo control (P < 0.05). While the impact of RB on BP is the same as that of a comparable quantity of caffeine, the increase occurs through different hemodynamic pathways with RB's effects primarily on cardiac parameters, while caffeine elicits primarily vascular effects. Additionally, the auxiliary components of RB (taurine, glucuronolactone, and B-group vitamins) do not appear to influence these pathways.

Cardio- and cerebrovascular responses to the energy drink Red Bull in young adults: a randomized cross-over study

PURPOSE

Energy drinks are beverages containing vasoactive metabolites, usually a combination of caffeine, taurine, glucuronolactone and sugars. There are concerns about the safety of energy drinks with some countries banning their sales. We determined the acute effects of a popular energy drink, Red Bull, on cardiovascular and hemodynamic variables, cerebrovascular parameters and microvascular endothelial function.

METHODS

Twenty-five young non-obese and healthy subjects attended two experimental sessions on separate days according to a randomized crossover study design. During each session, primary measurements included beat-to-beat blood pressure measurements, impedance cardiography and transcranial Doppler measurements for at least 20 min baseline and for 2 h following the ingestion of either 355 mL of the energy drink or 355 mL of tap water; the endothelial function test was performed before and two hours after either drink.

RESULTS

Unlike the water control load, Red Bull consumption led to increases in both systolic and diastolic blood pressure (p < 0.005), associated with increased heart rate and cardiac output (p < 0.05), with no significant changes in total peripheral resistance and without diminished endothelial response to acetylcholine; consequently, double product (reflecting myocardial load) was increased (p < 0.005). Red Bull consumption also led to increases in cerebrovascular resistance and breathing frequency (p < 0.005), as well as to decreases in cerebral blood flow velocity (p < 0.005) and end-tidal carbon dioxide (p < 0.005).

CONCLUSION

Our results show an overall negative hemodynamic profile in response to ingestion of the energy drink Red Bull, in particular an elevated blood pressure and double product and a lower cerebral blood flow velocity.

Double product reflects the predictive power of systolic pressure in the general population: evidence from 9,937 participants

BACKGROUND

The double product (DP), consisting of the systolic blood pressure (SBP) multiplied by the pulse rate (PR), is an index of myocardial oxygen consumption, but its prognostic value in the general population remains unknown.

METHODS

We recorded health outcomes in 9,937 subjects (median age, 53.2 years; 47.3% women) randomly recruited from 11 populations and enrolled in the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO) study. We obtained the SBP, PR, and DP for these subjects as determined through 24-hour ambulatory monitoring.

RESULTS

Over a median period of 11.0 years, 1,388 of the 9,937 study subjects died, of whom 536 and 794, respectively, died of cardiovascular (CV) and non-CV causes, and a further 1,161, 658, 494, and 465 subjects, respectively, experienced a CV, cardiac, coronary, or cerebrovascular event. In multivariate-adjusted Cox models, not including SBP and PR, DP predicted total, CV, and non-CV mortality (standardized hazard ratio [HR], ≥ 1.10; P ≤ 0.02), and all CV, cardiac, coronary, and stroke events (HR, ≥ 1.21; P < 0.0001). For CV mortality (HR, 1.34 vs. 1.30; P = 0.71) and coronary events (1.28 vs. 1.21; P = 0.26), SBP and the DP were equally predictive. As compared with DP, SBP was a stronger predictor of all CV events (1.39 vs. 1.27; P = 0.002) and stroke (1.61 vs. 1.36; P < 0.0001), and a slightly stronger predictor of cardiac events (1.32 vs. 1.22; P = 0.06). In fully adjusted models, including both SBP and PR, the predictive value of DP disappeared for fatal endpoints (P ≥ 0.07), coronary events (P = 0.06), and stroke (P = 0.12), or DP was even inversely associated with the risk of all CV and cardiac events (both P ≤ 0.01).

CONCLUSION

In the general population, we did not observe DP to add to risk stratification over and beyond SBP and PR.

The autonomic and rate pressure product responses of tai chi practitioners

Background:

Spectral analysis of autonomic nervous system activity can provide insight into cardiovascular function. Rate pressure product is the parameter often targeted pharmacologically to decrease the incidence of myocardial events.

Aim:

The purpose of this study was to investigate whether or not Tai Chi Chuan practitioners would demonstrate autonomic responses that would be more cardioprotective when compared to non-trained controls.

Materials and Methods:

This was a cross-sectional study that measured the autonomic responses and rate pressure product of 2 groups of subjects; a Tai Chi Chuan trained (n = 13) and non-trained sedentary controls (n = 13) at rest and during 2 stressor phases that simulated functional activities of daily living.

Results:

The Tai Chi group maintained a greater parasympathetic outflow at rest and during the isometric grip stressor phase (P<0.05). Sympathetic outflow, systolic blood pressure and rate pressure product were significantly lower in the Tai Chi group at rest, during the isometric grip and standing stressor phases (P<0.05).

Conclusion:

Although a cause-and-effect relationship cannot be concluded in this study, the Tai Chi group was able to demonstrate efficiency of the myocardium with suppressed rate pressure product values and autonomic responses that favored parasympathetic outflow. This type of training may complement non-pharmacological anti-hypertensive therapy.

Prediction of true circulatory decompensation in chronic heart failure for optimal timing of mechanical circulatory support: non-invasive arterial-ventricular coupling

Background: Prospective comparative studies to predict the risk of hemodynamic deterioration in patients referred for transplantation were performed on the basis of standard invasive and non-invasive data and new wave intensity (WI) parameters. Methods and results: Study Group 1 consisted of 151 consecutive outpatients (age 48.7 ± 12 years; 110 men) with end-stage dilative cardiomyopathy. Group 2, consisting of 11 consecutive patients (age 50 ± 11 years; 6 men) with sinus rhythm and “true” decompensation, was used to create “critical values” of WI. There were no demographic or somatic (weight and height) differences between the groups. The follow-up period of ambulatory patients was 31 ± 8 months. Non-invasive WI was studied in the common carotid artery. Complete invasive and non-invasive data were also recorded on the day of investigation. During follow-up 44 pts were lost; there were 15 cardiac deaths (10%), life-saving ventricular assist device implantation in 10 (6.6%) and transplantation in 19 (12.7%). For statistical purposes this group was named the “events” Group B (n = 44). A predisposing factor for events (death, “true” decompensation and “urgent” transplantation in ambulatory patients) was low first peak (“cut-off value” assessed in Group 2 < 4100 mmHg*s³) (OR 45.6, CI 14.5–143.3, p < 0.001). Less powerful predictors of the risk of deterioration were pulmonary capillary pressure (PCP), diastolic pulmonary artery pressure (PAP) and E/A mitral wave relation (p = 0.05). Conclusions: The new ventricular-arterial coupling parameter 1st peak of WI can potentially be used to distinguish patients at high risk for true deterioration and death. This parameter can be used to predict the need for assist device implantation.

Baroreflex stabilization of the double (pressure-rate) product at 0.05 Hz in conscious rabbits

The product of heart rate (HR) and systolic blood pressure (SBP), the double product (DP), is an indirect index of cardiac oxygen consumption. We used spectral analysis to test the hypothesis that baroreflex adjustments of HR stabilize the DP during spontaneous variations in SBP. SBP and HR were recorded by telemetry in five male conscious rabbits. HR and SBP power spectra each exhibited a low frequency peak at approximately 0.05 Hz that was associated with high (>0.5) spectral coherence and a positive phase relationship between SBP and HR (SBP leading). A prominent peak was absent in the spectra of their product, suggesting that SBP and HR interacted to reduce DP variability in this frequency region. In contrast, a prominent 0.05-Hz peak was present in the power spectrum of calculated surrogates of the DP in which reflex interactions between HR and SBP had been removed. Our results suggest that baroreflex adjustments of HR stabilize the DP during spontaneous low-frequency variations in SBP in conscious rabbits.