Systolic Pressure Product Research Articles

Abstract 16047: Quantifying the Cardiovascular Burden of Extreme Heat: A Meta-Analysis of Over 400 Laboratory-Based Heat Exposure Studies

Background: Heat waves are associated with increased fatalities from cardiovascular events, which has been attributed to increased cardiac strain secondary to the effects of heat on cardiac function. However, our understanding of these adjustments has come primarily from laboratory research employing insulated/encapsulated heating modalities (hot water perfusion suits). We evaluated whether the cardiac responses seen in this work reflect those experienced in studies exposing participants to high ambient temperatures. Methods: We systematically reviewed studies published up to January 2023 examining cardiac outcomes in adults rendered hyperthermic with water perfusion suits or unencapsulated exposure in a climate chamber. Mixed effects meta-analyses were conducted to evaluate whether changes in each outcome with increasing core temperature were modified by heating modality. We also estimated associations (natural spline) between ambient heat index and thermal and cardiac responses in the climate chamber studies. Results: 584 effect estimates of the heat-induced increase in heart rate (primary outcome) from 406 studies were included (~6800 participant exposures). Heart rate was 7 beats/min [95% CI: 3, 13] greater in the perfusion suit vs. climate chamber studies for similar increases in core temperature (P<0.001). Likewise, there were greater elevations in cardiac output (slope difference: 1.2 L/min/°C [0.1, 2.3]), systolic pressure (14 mm Hg/°C [3, 24]), and rate pressure product (2923 mm Hg·beats/min/°C [1027, 4808]) with rises in core temperature in the perfusion suit compared to climate chambers studies (P≤0.036). In the climate chamber studies, core temperature and heart rate increased as much as 1.0°C [0.8, 1.3] and 31 beats/min [16, 37] (P<0.001) in conditions reflective of deadly North American heat waves (heat index: 50-67°C). Conclusions: Our understanding of the effect of heat on cardiovascular responses primarily comes from encapsulated heating modalities, which we show overestimate heat-induced cardiac burden. To support public health research on extreme heat, we provide the first empirical estimates demonstrating considerable thermal and cardiac strain is experienced in conditions reflective of deadly heat waves.

The mediating role of adiposity in the longitudinal association between cardiorespiratory fitness and blood pressure in adolescents: LabMed cohort study

The aim of this prospective cohort study was to examine whether the association between the cardiorespiratory fitness (CRF) at baseline and blood pressure (BP) at follow-up is mediated by adiposity in adolescents. The sample comprised 734 adolescents (349 girls) aged 12-18years from the LabMed Physical Activity Cohort Study. The variables of interest were measured in 2011 (baseline) and in 2013 (2-year follow-up). CRF was assessed by the 20-m shuttle run test. Body mass index, waist circumference, body fat percentage, pubertal status and resting BP were assessed according to standard procedures. Boot-strapped mediation procedures were performed, and indirect effects (IE) with confidence intervals (CI) not including zero were considered statistically significant. After adjusting for potential confounders, body mass index acted as a mediator of the relationship between CRF and systolic BP (IE=-0. 023; CI=-0.039; -0.009), pulse pressure (IE=-0.023; CI=-0.034; -0.012) and rate product pressure (IE=-2.839; CI=-5.329; -0.340). Similar results were obtained for waist circumference as mediator for systolic BP (IE=-0.019; CI=-0.033; -0.005), pulse pressure (IE=-0.017; CI=-0.028; -0.007) and rate product pressure (IE=-3.793; CI=-6.097; -1.689). Likewise, body fat percentage mediated the association for: systolic BP (IE=-0.029; CI=-0.048; -0.010), pulse pressure (IE=-0.027; CI=-0.041; -0.013) and rate product pressure (IE=-4.280; CI=-7.488; -1.264). Adiposity mediated the association between CRF and BP in adolescents. Therefore, both optimal CRF and adiposity levels are important to maintain normal BP ranges throughout adolescence.

Study on the use of CT three-dimensional reconstruction technique for guiding tracheal intubation with rigid fiber bronchoscope in difficult airway

OBJECTIVE To evaluate the significance of CT three-dimensional reconstruction technique for guiding tracheal intubation with rigid fiber bronchoscope in difficult airway. METHODS In this study, 44 patients undergoing selective operation of ASA (American Society of Anesthesiologists physical status) I to II, neck stiffness, neck trauma needed braked, or severe cervical spondylosis were selected. The patients were randomly divided into two groups: 24 cases in the experimental group (group E) and 20 cases in the control group (group C). The stylets of the rigid fiber bronchoscopes were shaped according to the CT three-dimensional reconstruction images and parameters obtained before surgery. The rigid fiber bronchoscopes shaped according to the CT three-dimensional reconstruction images were used in group E, while the rigid fiber bronchoscopes with the original angles were used in group C. Tracheal intubation operations were all performed by an anesthesiologist who had more than 10 years' clinical experience and mastered in rigid endoscopic intubation techniques. The first attempt success rate and the total success rate of tracheal intubation, intubation time, blood pressure, heart rate and pulse oxygen saturation at different time points including pre-induction, immediately after intubation, 1-5 minutes after intubation, and intubation related complications within 24 hours were recorded. RESULTS The total success rate of intubation in the two groups were both 100%. The first attempt success rate of intubation was 96% in group E, and 70% in group C. The first attempt success rate of group E was higher than that of group C. The intubation time of group E was (20.7± 10.6) s, and (21.5 ± 17.6) s of group C. Group E was shorter than that of group C, but there was no significant difference (P > 0.05). RPP equaled the product of heart rate and systolic pressure, which represented the stress reaction of intubation on hemodynamics, was lower in group C at T0, T1, T2, T4 and T5 separately than that in group E, but there was no significant difference (P>0.05). There was no significant difference in tracheal intubation related complications between the two groups (P>0.05). CONCLUSION CT three-dimensional reconstruction technique has certain guiding significance in difficult tracheal intubation with rigid fiber bronchoscope in patients with fixed cervical spine.

Cardiovascular responses to low-intensity isometric handgrip exercise in coronary artery disease: effects of posture

BackgroundCoronary artery disease (CAD) lead to cardiovascular autonomic control disfunctions that can worsen exercise and/or posture adjustments. ObjectivesTo verify the cardiovascular responses to low-intensity isometric handgrip exercise performed in different postures in CAD patients. This study tested the hypothesis that the posture influences the cardiovascular responses during isometric handgrip exercise and that the presence of CAD leads to greater cardiovascular stress during this type of exercise. MethodsWe investigated cardiovascular responses to isometric handgrip exercise in 15 CAD patients (CADG) and 15 health matched-control (CG). The subjects performed isometric handgrip exercise at 30% of maximum voluntary contraction until exhaustion in SUPINE, SITTING and STANDING positions. Systolic arterial pressure, diastolic arterial pressure, mean blood pressure, heart rate, peripheral vascular resistance, cardiac output, stroke volume and double product were measured during rest (baseline), exercise (peak value) and recovery in the 1st minute (REC1). Delta PB (ΔPB, peak minus baseline) and PR1 (ΔPR1, peak minus REC1) were calculated. ResultsHigher ΔPB and ΔPR1 of systolic and mean arterial pressure and double product were observed in STANDING when compared to SITTING and/or SUPINE. CADG showed higher ΔPB of systolic and mean arterial pressure in all postures and higher ΔPR1 of strove volume in the SITTING. ConclusionWe concluded that the posture during isometric handgrip exercise influences the cardiovascular responses with STANDING leading to higher cardiovascular stress. CAD promoted higher arterial pressure responses however these responses were physiological and expected due to the presence of disease and type of exercise.

Early Proteome Shift and Serum Bioactivity Precede Diesel Exhaust-induced Impairment of Cardiovascular Recovery in Spontaneously Hypertensive Rats

Single circulating factors are often investigated to explain air pollution-induced cardiovascular dysfunction, yet broader examinations of the identity and bioactivity of the entire circulating milieu remain understudied. The purpose of this study was to determine if exposure-induced cardiovascular dysfunction can be coupled with alterations in both serum bioactivity and the circulating proteome. Two cohorts of Spontaneously Hypertensive Rats (SHRs) were exposed to 150 or 500 μg/m3 diesel exhaust (DE) or filtered air (FA). In Cohort 1, we collected serum 1 hour after exposure for proteomics analysis and bioactivity measurements in rat aortic endothelial cells (RAECs). In Cohort 2, we assessed left ventricular pressure (LVP) during stimulation and recovery from the sympathomimetic dobutamine HCl, one day after exposure. Serum from DE-exposed rats had significant changes in 66 serum proteins and caused decreased NOS activity and increased VCAM-1 expression in RAECs. While rats exposed to DE demonstrated increased heart rate at the start of LVP assessments, heart rate, systolic pressure, and double product fell below baseline in DE-exposed rats compared to FA during recovery from dobutamine, indicating dysregulation of post-exertional cardiovascular function. Taken together, a complex and bioactive circulating milieu may underlie air pollution-induced cardiovascular dysfunction.

Diferentes ordens dos exercícios durante o método circuito não alteram as respostas hemodinâmicas - Estudo Piloto

Introduo: O efeito da ordem dos exerccios no Treinamento Circuito (TC) sobre variveis hemodinmicas inconclusivo. Objetivo: Avaliar o efeito de diferentes ordens de execuo nas respostas hemodinmicas agudas no TC. Mtodos: Onze homens foram recrutados. As sesses de treinamento foram compostas pela seguinte sequncia: Sequncia A: multiarticulares/monoarticulares; Sequncia B: monoarticulares/multiarticulares, realizados a 60% de 1-RM com intervalo de um minuto. Ambos circuitos foram compostos por trs passagens com oito estaes. Os desfechos foram: presso arterial sistlica (PAS), diastlica (PAD), frequncia cardaca (FC) e duplo produto (DP). Para comparaes utilizou-se ANOVA two-way medidas repetidas considerando p0.05. Resultados: Os valores da FC foram significativamente mais altos durante e aps o exerccio em comparao ao momento pr (p0,001), aumento do DP (p 0,001) e diminuio da PAS (p0,001) aps os treinos, independente da ordem dos exerccios. Concluso: O mtodo de TC eficiente em promover o efeito hipotensor ps-exerccio independente da ordem de execuo.

Computational prediction of the effects of the intra-aortic balloon pump on heart failure with valvular regurgitation using a 3D cardiac electromechanical model

Intra-aortic balloon pump (IABP) is normally contraindicated in significant aortic regurgitation (AR). It causes and aggravates pre-existing AR while performing well in the event of mitral regurgitation (MR). Indirect parameters, such as the mean systolic pressure, product of heart rate and peak systolic pressure, and pressure–volume are used to quantify the effect of IABP on ventricular workload. However, to date, no studies have directly quantified the reduction in workload with IABP. The goal of this study is to examine the effect of IABP therapy on ventricular mechanics under valvular insufficiency by using a computational model of the heart. For this purpose, the 3D electromechanical model of the failing ventricles used in previous studies was coupled with a lumped parameter model of valvular regurgitation and the IABP-treated vascular system. The IABP therapy was disturbed in terms of reducing the myocardial tension generation and contractile ATP consumption by valvular regurgitation, particularly in the AR condition. The IABP worsened the problem of ventricular expansion induced as a result of the regurgitated blood volume during the diastole under the AR condition. The IABP reduced the LV stroke work in the AR, MR, and no regurgitation conditions. Therefore, the IABP helped the ventricle to pump blood and reduced the ventricular workload. In conclusion, the IABP partially performed its role in the MR condition. However, it was disturbed by the AR and worsened the cardiovascular responses that followed the AR. Therefore, this study computationally proved the reason for the clinical contraindication of IABP in AR patients.

Pulmonary function, white blood corpuscles & haemoglobin levels in asymptomatic light smokers and non-smokers

Context: Smoking, a risk factor for several diseases has also been reported as the largest preventable cause of morbidity and mortality globally. Tobacco smoking is associated with a decrease in lung function in smokers when compared to non-smokers. Aims: To study and compare pulmonary function, WBC count and Hb levels in asymptomatic light smokers and non-smokers. Settings and Design: Case control study. Methods and Material: Patient relatives or subjects who had come for health check with a known history of smoking and apparently asymptomatic were recruited as our study subjects (n = 49). Healthy volunteers were also recruited from patient relatives. Subjects without any known history of smoking were selected as controls (n = 50). Statistical analysis used: Data was analysed using SPSS V-19. P value ≤0.05 was considered significant. Results: A statistically significant difference was found in total leucocyte count in smokers (P = 0.004) when compared to non-smokers. There was also a statistically significant increase in absolute neutrophil (P = 0.021), monocyte (P = 0.004) and eosinophil (P = 0.075) counts in smokers. FEV1/FVC (P = 0.005) and FEF 75 (P = 0.027) was significantly higher in non-smokers when compared to smokers. No significant difference was observed in haemoglobin concentration and differential leucocyte count, pulse rate, systolic pressure, diastolic pressure and rate pressure product among the two groups. Conclusions: The present study gives ample evidence for the damage to the respiratory system along with activation of immune system as evident from a significant lowering of small airway patency and increased white cell counts

Vagal nerve stimulation started just prior to reperfusion limits infarct size and no-reflow.

Vagal nerve stimulation (VNS) started prior to, or during, ischemia has been shown to reduce infarct size. Here, we investigated the effect of VNS when started just prior to, and continued during early, reperfusion on infarct size and no-reflow and studied the underlying mechanisms. For this purpose, swine (13 VNS, 10 sham) underwent 45 min mid-LAD occlusion followed by 120 min of reperfusion. VNS was started 5 min prior to reperfusion and continued until 15 min of reperfusion. Area at risk, area of no-reflow (% of infarct area) and infarct size (% of area at risk), circulating cytokines, and regional myocardial leukocyte influx were assessed after 120 min of reperfusion. VNS significantly reduced infarct size from 67 ± 2 % in sham to 54 ± 5 % and area of no-reflow from 54 ± 6 % in sham to 32 ± 6 %. These effects were accompanied by reductions in neutrophil (~40 %) and macrophage (~60 %) infiltration in the infarct area (all p < 0.05), whereas systemic circulating plasma levels of TNFα and IL6 were not affected. The degree of cardioprotection could not be explained by the VNS-induced bradycardia or the VNS-induced decrease in the double product of heart rate and left ventricular systolic pressure. In the presence of NO-synthase inhibitor LNNA, VNS no longer attenuated infarct size and area of no-reflow, which was paralleled by similarly unaffected regional leukocyte infiltration. In conclusion, VNS is a promising novel adjunctive therapy that limits reperfusion injury in a large animal model of acute myocardial infarction.Electronic supplementary materialThe online version of this article (doi:10.1007/s00395-015-0508-3) contains supplementary material, which is available to authorized users.

Ambulatory 24–hour cardiac oxygen consumption and blood pressure–heart rate variability: effects of nebivolol and valsartan alone and in combination

We compared an angiotensin receptor blocker (valsartan; VAL), a beta–blocker (nebivolol; NEB) and the combination of NEB/VAL with respect to 24–hour myocardial oxygen consumption (determined by 24–hour ambulatory heart rate–central systolic pressure product [ACRPP]) and its components. Subjects with hypertension (systolic blood pressure >140 or diastolic blood pressure >90; n = 26) were studied in a double–blinded, double-dummy, forced–titration, crossover design with 3 random-order experimental periods: VAL 320 mg, NEB 40 mg, and NEB/VAL 320/40 mg daily. After 4 weeks of each drug, ambulatory pulse wave analysis (MobilOGraph) was performed every 20 minutes for 24 hours. All three treatments resulted in nearly identical brachial and central systolic blood pressures. NEB alone or in combination with VAL resulted in lower ACRPP (by 11%–14%; P < .001 each) and heart rate (by 18%–20%; P < .001 each) compared with VAL, but stroke work (ACRPP per beat) was lower with VAL. Relative and adjusted variability (standard deviation and coefficient of variation) of heart rate were also lower with NEB and NEB/VAL than VAL. Results in African Americans, the majority subpopulation, were similar to those of the entire treatment group. We conclude that the rate–slowing effects of NEB cause ambulatory cardiac myocardial oxygen consumption to be lower with NEB monotherapy or NEB/VAL combination therapy than with VAL monotherapy. NEB/VAL is not superior to NEB alone in controlling heart rate, blood pressure, or ACRPP. Heart rate variability but not ACRPP variability is reduced by NEB or the combination NEB/VAL. There is no attenuation of beta–blocker–induced rate–slowing effects of in African Americans.

LOSS OF HOMOARGININE IS RESPONSIBLE FOR CARDIAC DYSFUNCTION IN CREATINE-DEFICIENT ARGININE:GLYCINE AMIDINOTRANSFERASE (AGAT) KNOCKOUT MICE

RationaleCreatine is an intrinsic component of cardiac energy metabolism. We therefore hypothesised that genetic deletion of the creatine biosynthetic enzyme, arginine:glycine amidinotransferase (AGAT KO), would result in impaired cardiac function...

OP-273 Computational Quantification of the Cardiac Energy Consumption during Intra-Aortic Balloon Pumping by Using a Cardiac Electromechanics model

To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure–volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes.

Ejection fractions and pressure–heart rate product to evaluate cardiac efficiency

Ejection fractions, derived from ventricular volumes, and double product, related to myocardial oxygen consumption, are important diagnostic parameters, as they describe the efficiency with which oxygen is consumed. Present technology often allows only intermittent determination of physiological status. This deficiency may be overcome if ejection fractions and myocardial oxygen consumption could be determined from continuous blood pressure and heart rate measurements. The purpose of this study is to determine the viability of pressure-derived ejection fractions and pressure-heart rate data in a diverse patient population and the use of ejection fractions to monitor patient safety. Volume ejection fractions, derived from ventricular volumes, EF(V), are defined by the ratio of the difference of end-diastolic volume, EDV, and end-systolic volume, ESV, to EDV. In analogy, pressure ejection fraction, EF(P), may be defined by the ratio of the difference of systolic arterial pressure, SBP, and diastolic arterial pressure, DBP, to SBP. The pressure-heart rate (heart rate: HR) is given by the product of systolic pressure and heart rate, SBP × HR. EF(P) and SBP × HR data were derived for all patients (n = 824) who were admitted in 2008 to the ICU of a university hospital at the specific time 30min prior to leaving the ICU whether as survivors or non-survivors. The results are displayed in an efficiency/pressure-heart rate diagram. The efficiency/pressure-heart rate diagram reveals one subarea populated exclusively by survivors, another subarea populated statistically significant by non-survivors, and a third area shared by survivors and non-survivors. The efficiency/pressure-heart rate product relationship may be used as an outcome criterion to assess survival and to noninvasively monitor improvement or deterioration in real time to improve safety in patients with diverse dysfunctions.

The acute effects of waterpipe smoking on lung function and exercise capacity in a pilot study of healthy participants

Context: Waterpipe tobacco smoking (WTS) has gained popularity, but its physiologic effects have not been extensively studied: rather, studies have focused on WTS’s chronic effects or have evaluated limited respiratory/cardiac parameters.Objective: We sought to characterize in a more detailed manner the acute effects of WTS on lung function and exercise capacity.Method: We recruited 24 healthy WTS males. We used a pilot single-group pre-test (abstained from WTS for ≥48 h) post-test (within 0.5 h of a 45-min WTS session) design. We performed spirometry, diffusing lung capacity and time-limited CPE testing (CPET; cycloergometer; 2-min 20-Watt warm-up and 25-Watt increase every 2-min for 10 min).Results: Mean age was 20.4 years; Post-WTS, the following significant changes were observed: CO level increased from 3.7 ppm to 24.4; oxygen consumption decreased (from 1.86 L/min to 1.7); baseline respiratory rate increased (from 17.7 breath/min to 19.7); forced expiratory flow over the middle half of the forced vital capacity decreased (from 5.51 L to 5.29); and perceived exertion (measured by Borg scale) at mid and peak exercise increased. Baseline resting systolic blood pressure, pulse pressure, and pulse pressure product increased post-WTS (from 118.9 mmHg to 129.2; from 45.3 mmHg to 55.6; and from 9.9 mmHg/min to 11.1 post-WTS, respectively). During exercise, a decrease in oxygen pulse was observed post-WTS (from 10.89 ml/beat to 9.97), while the heart rate-oxygen consumption relationship increased post-WTS (from 3.52 beats/ml/kg to 3.91).Conclusion: Acute WTS appears to induce impairment in lung function and exercise capacity. Larger studies are warranted to further characterize the nature and extent of such impairment.

Development and Evaluation of a Treadmill-Based Exercise Tolerance Test in Cardiac Rehabilitation

Cardiac rehabilitation exercise prescriptions should be based on exercise stress tests; however, limitations in performing stress tests in this setting typically force reliance on subjective measures like the Duke Activity Status Index (DASI). We developed and evaluated a treadmill-based exercise tolerance test (ETT) to provide objective physiologic measures without requiring additional equipment or insurance charges. The ETT is stopped when the patient's Borg scale rating of perceived exertion (RPE) reaches 15 or when any sign/symptom indicates risk of an adverse event. Outcomes of the study included reasons for stopping; maximum heart rate, systolic blood pressure, and rate pressure product; and adverse events. We tested equivalence to the DASI as requiring the 95% confidence interval for the mean difference between DASI and ETT metabolic equivalents (METs) to fall within the range (–1, 1). Among 502 consecutive cardiac rehabilitation patients, one suffered a panic attack; no other adverse events occurred. Most (80%) stopped because they reached an RPE of 15; the remaining 20% were stopped on indications that continuing risked an adverse event. Mean maximum systolic blood pressure, heart rate, and rate pressure product were significantly (P < 0.001) below thresholds of the American Association of Cardiovascular and Pulmonary Rehabilitation. Two patients' heart rates exceeded 150 beats per minute, but their rate pressure products remained below 36,000. The mean difference between DASI and ETT METs was −0.8 (–0.98, −0.65), indicating equivalence at our threshold. In conclusion, the ETT can be performed within cardiac rehabilitation, providing a functional capacity assessment equivalent to the DASI and objective physiologic measures for developing exercise prescriptions and measuring progress.

11C-Acetate Clearance as an Index of Oxygen Consumption of the Right Myocardium in Idiopathic Pulmonary Arterial Hypertension: A Validation Study Using 15O-Labeled Tracers and PET

Idiopathic pulmonary arterial hypertension (IPAH) results in increased right ventricular (RV) workload and oxygen demand. It has been shown that myocardial oxygen consumption (MVO2) of the hypertrophied right ventricle of IPAH patients can be measured using PET and (15)O-labeled tracers. This method is, however, not very suitable for routine clinical practice. The purpose of the present study was to assess whether MVO2 can also be determined in the right ventricle of IPAH patients from the clearance of (11)C-acetate, a simple method that is in use for MVO2 measurements of the left myocardium. Seventeen of 26 IPAH patients performed the total PET study. Nine other patients were scanned only for (11)C-acetate. (15)O-H2O, (15)O-O2, and (15)O-CO scans were used to derive RV flow, oxygen extraction fraction, and blood volume, respectively, from which RV MVO2 was calculated. The rate of clearance determined by monoexponential curve fitting (K(mono)) and the efflux rate constant k2 were derived from the (11)C-acetate scan. The RV rate-pressure product was also determined by means of right heart catheterization, as an index of the RV MVO2, and was calculated as the product of systolic pulmonary artery pressure and heart rate. Both (11)C-acetate clearance rates, K(mono) (R(2) = 0.41, P = 0.006) and k2 (R(2) = 0.45, P = 0.003), correlated with RV MVO2. They also correlated with RV rate-pressure product (K(mono), R(2) = 0.41, P = 0.0005; k2, R(2) = 0.48, P < 0.0001). (11)C-acetate clearance rates correlated moderately with quantitative RV MVO2 measurements in IPAH. Therefore, (11)C-acetate PET can be used only as an index of RV oxidative metabolism in IPAH patients.

Comparative Study of effect of Slow and Fast Suryanamaskar on Work Load of Heart in Normal Human Subjects

Objective: To compare the work load on heart by slow and fast suryanamaskar. Background: Suryanamaskar, an integral component of yoga is an excellent practice that stretches and tones the whole body. Various schools of yoga differ in the practice of suryanamaskar (SN). Some schools advocate performance in a slow manner in tune with slow breathing, while others advocate a rapid method of performing multiple rounds in a fast manner similar to physical exercise. It has been suggested that SN at different speeds provides different benefits. In the present study, we planned to determine the immediate effect of slow and fast suryanamaskar on heart rate and blood pressure of normal young volunteers. Method: Thirty healthy school children were randomly divided into two groups of 15 each. Group I underwent training in fast suryanamaskar while group II were given training in slow suryanamaskar. Blood pressure and heart rate were determined before and immediately after the practice of suryanamaskar in both the groups. Result: Fast suryanamaskar produced a significant increase in systolic pressure, pulse pressure and rate pressure product. On the other hand, slow suryanamaskar produced a significant decrease in diastolic pressure but there was no significant change in systolic pressure or rate-pressure product. Thus it was evident that the cardiovascular response to suryanamaskar depends on the manner in which it is performed. Slow suryanamaskar is non-taxing to the heart and hence can be prescribed to hypertensive patients and for rehabilitation of cardiac patients. Conclusion: It is recommended that slow suryanamaskar may be used as a lifestyle component for school children and also for subjects with pre and stage I hypertension and mild degree cardiac patients undergoing rehabilitation.

Computational Quantification of the Cardiac Energy Consumption during Intra-Aortic Balloon Pumping Using a Cardiac Electromechanics Model

To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently.

The predictive ability of blood pressure in elderly trial patients

To assess the impact of the blood pressure (BP) profile on cardiovascular risk in the Medical Research Council (UK) elderly trial; investigate whether the effects of hypertensive drugs in reducing event rates are solely a product of systolic pressure reduction. Using longitudinal BP data from 4396 hypertensive patients, the general trend over time was estimated using a first-stage multilevel model. We then investigated how BP acted alongside other BP-related covariates in a second-stage 'time-to-event' statistical model, assessing risk for stroke events and coronary heart disease (CHD). Differences in outcome prediction between diuretic, β-blocker and placebo treatment arms were investigated. The β-blocker arm experienced comparatively poor control of current SBP, episodic peaks and variability in BP levels. After adjusting for the mean level, variability in SBP over time was significant: risk ratio was 1.15 [95% confidence interval (CI): 1.01-1.31] across all patients for stroke events. The risk ratio for current SBP was 1.36 (95% CI: 1.16-1.58). Current DBP and variability in DBP also predicted stroke independently: risk ratios was 1.43 and 1.18, respectively. The risk factors exhibited weaker associations with CHD risk; only the highest measured value and variability in SBP showed a statistically significant association: risk ratios were 1.26 and 1.16, respectively. Individual risk characterization could be augmented with additional prognostic information, besides current SBP, including current diastolic pressure, temporal variability over and above general trends and historical measurements.

The association of rate pressure product (RPP) and myocardial perfusion imaging (MPI) findings: a preliminary study

The product of heart rate and systolic blood pressure, termed as rate-pressure product (RPP), is a very reliable indicator of myocardial oxygen demand and is widely used clinically. There have been previous attempts to describe the relationship between RPP and the onset of pain in angina pectoris. The current study aimed to evaluate the association between RPP results and scan findings. In total, 497 patients with suspected coronary artery disease (CAD) underwent gated, single-photon emission computed tomography (SPECT) imaging with dipyridamole, exercise, or dobutamine stress, and were included in this study. Baseline and maximum heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and electrocardiogram (ECG) results were recorded. The rate-pressure product (RPP) was calculated as the product of heart rate and systolic arterial pressure for both baseline and maximum measures. The difference between the RPP max and the basal RPP is known as the RPP reserve. Researchers also obtained semi-quantitative analyses of myocardial perfusion imaging (MPI), using gated software, demographic information, risk factors of CAD, and pretest likelihoods of CAD using nomograms. Four hundred and ninety-seven cases, including 426 patients with dipyridamole stress, 59 with exercise stress, and 12 with dobutamine stress, underwent myocardial perfusion imaging. Scan results were positive in 194 (45.5%) and negative in 232 (54.5%) patients with dipyridamole stress. In patients with exercise stress, the scan was positive in 24 (40.7%) cases and negative in 35 (59.3%) cases. In dobutamine stressed patients, the scan was positive in 6 (50%) cases and negative in the 6 remaining cases. Dipyridamole stress resulted in a significant difference between HR at rest and at maximum (28.95 ± 24.53, p-value<0.0001), between systolic BP at rest and maximum (6.75 ± 12.50, p-value<0.0001) and between diastolic BP at rest and maximum (1.45 ± 5.80; p-value<0.0001). There was a significant correlation between sum stress scores (SSS) and reserved RPP (r= -0.12, p-value<0.001) which, in dipyridamole patients, was r=-0.18, p-value=0.0001). In addition, there was a significant association between reserved RPP and risk of CAD (p-value<0.001). In the patients with dipyridamole stress, the ejection fraction (EF) change (odds ratio =0.92; 95% CI: 0.86-0.98; p=0.01), reserve RPP (odds ratio =1.00; 95% CI: 1.00-1.00; p=0.04), risk of CAD (odds ratio =5.80; 95% CI: 3.21-10.50; p<0.0001) and age (odds ratio =0.94; 95% CI: 0.89-0.98; p=0.01) were associated significantly with MPI results, using multiple logistic regressions. The study demonstrated that RPP is associated with MPI findings using gated SPECT imaging with dipyridamole stress. However, to confirm this preliminary result, further studies are mandatory.