Changes In Myocardial Oxygen Consumption Research Articles

Biologically derived epicardial patch induces macrophage mediated pathophysiologic repair in chronically infarcted swine hearts

There are nearly 65 million people with chronic heart failure (CHF) globally, with no treatment directed at the pathologic cause of the disease, the loss of functioning cardiomyocytes. We have an allogeneic cardiac patch comprised of cardiomyocytes and human fibroblasts on a bioresorbable matrix. This patch increases blood flow to the damaged heart and improves left ventricular (LV) function in an immune competent rat model of ischemic CHF. After 6 months of treatment in an immune competent Yucatan mini swine ischemic CHF model, this patch restores LV contractility without constrictive physiology, partially reversing maladaptive LV and right ventricular remodeling, increases exercise tolerance, without inducing any cardiac arrhythmias or a change in myocardial oxygen consumption. Digital spatial profiling in mice with patch placement 3 weeks after a myocardial infarction shows that the patch induces a CD45pos immune cell response that results in an infiltration of dendritic cells and macrophages with high expression of macrophages polarization to the anti-inflammatory reparative M2 phenotype. Leveraging the host native immune system allows for the potential use of immunomodulatory therapies for treatment of chronic inflammatory diseases not limited to ischemic CHF.

Histopathologic Validation of Stress T1 Mapping in Myocardial Ischemia: Another Step toward Clinical Translation?

Histopathologic Validation of Stress T1 Mapping in Myocardial Ischemia: Another Step toward Clinical Translation?

Differences in myocardial oxygen consumption between low-risk pregnancies and pregnancies with hypertensive disorders of pregnancy

Rate-Pressure Product (RPP) has been used in non-pregnant adults as a surrogate for myocardial oxygen consumption (MOC), a dynamic non-invasive index of changes in cardiovascular (CV) demand. We sought to compare pre-conceptional (PC), antepartum (AP), and postpartum (PP) changes in MOC between low-risk pregnancies and those complicated by hypertensive disorders of pregnancy (HDP).

엘리트 태권도 선수의 경기 중 심박수, 혈중 젖산, 혈압, 심근산소소비량의 변화

In this study, by observing the changes in heart rate, blood lactate, blood pressure, and myocardial oxygen consumption during the entire competition, male and female Taekwondo elite athletes performed 3 rounds of 3 minutes for men and 3 times for 2 minutes for women, respectively, the exact exercise intensity of Taekwondo was evaluated. The purpose is to provide basic data for understanding and to present the theoretical basis for planning scientific training. The subjects of this study consisted of 16 university players, 8 male and 8 female. Heart rate, blood pressure, and blood lactate were measured, and myocardial oxygen consumption was calculated from the measured systolic blood pressure and heart rate. Measurement time is at rest, end of round 1, rest 1(1 min), end of round 2, rest 2 (1 min), end of round 3, rest 3 (1 min), recovery period (3 min) after game 8 times classified as.<BR>As a result of this 1. There was no significant difference between the sexes in the change of heart rate in the Taekwondo competition, and there was a significant difference between the 1st/2nd and 1st/3rd rounds during the R competition, which corresponds to 90-95% of the maximum heart rate. 2. There was no significant difference between the sexes in the change of blood lactate, and there was a significant difference at the end of each rotation, which corresponds to an approximately 3-fold increase at the end of the 3rd rotation compared to the rest. 3. As for the change in blood pressure, there was no significant difference in systolic blood pressure between the sexes, and there was a significant difference in diastolic blood pressure. Male athletes were higher than female athletes by time. 4. The change in myocardial oxygen consumption showed a significant difference between the sexes, and it was found to be about 2-3 times higher than at rest.

Mental Workload Alters Heart Rate Variability, Lowering Non-linear Dynamics.

Mental workload is known to alter cardiovascular function leading to increased cardiovascular risk. Nevertheless, there is no clear autonomic nervous system unbalance to be quantified during mental stress. We aimed to characterize the mental workload impact on the cardiovascular function with a focus on heart rate variability (HRV) non-linear indexes. A 1-h computerized switching task (letter recognition) was performed by 24 subjects while monitoring their performance (accuracy, response time), electrocardiogram and blood pressure waveform (finger volume clamp method). The HRV was evaluated from the beat-to-beat RR intervals (RRI) in time-, frequency-, and informational- domains, before (Control) and during the task. The task induced a significant mental workload (visual analog scale of fatigue from 27 ± 26 to 50 ± 31 mm, p < 0.001, and NASA-TLX score of 56 ± 17). The heart rate, blood pressure and baroreflex function were unchanged, whereas most of the HRV parameters markedly decreased. The maximum decrease occurred during the first 15 min of the task (P1), before starting to return to the baseline values reached at the end of the task (P4). The RRI dimension correlation (D2) decrease was the most significant (P1 vs. Control: 1.42 ± 0.85 vs. 2.21 ± 0.8, p < 0.001) and only D2 lasted until the task ended (P4 vs. Control: 1.96 ± 0.9 vs. 2.21 ± 0.9, p < 0.05). D2 was identified as the most robust cardiovascular variable impacted by the mental workload as determined by posterior predictive simulations (p = 0.9). The Spearman correlation matrix highlighted that D2 could be a marker of the generated frustration (R = –0.61, p < 0.01) induced by a mental task, as well as the myocardial oxygen consumption changes assessed by the double product (R = –0.53, p < 0.05). In conclusion, we showed that mental workload sharply lowered the non-linear RRI dynamics, particularly the RRI correlation dimension.

Acute Cardiovascular Responses to a Session of Bikram Yoga: A Pilot Uncontrolled Trial.

Main cardiovascular parameters such as heart rate (HR), blood pressure, and myocardial oxygen consumption (MOC) are tightly regulated by a multifactorial, nonlinear control system. Increased HR because of physical activity is often accompanied by an increase in blood pressure. Postural changes have an effect on the baroreceptors, and stretching exercises and isometric contractions modulate muscle mechanoreceptors eliciting increases in blood pressure. However, a hot environment increases the core temperature inducing vasodilation and plasma volume changes that might contribute to a drop in blood pressure. During the practice of Bikram yoga, all these factors converge and little is known about the resulting changes in blood pressure and MOC. Sixteen apparently healthy female volunteers, regular practitioners of Bikram yoga, were evaluated during a 90 min session. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured immediately after each posture and HR was measured continuously during the practice. HR and estimated MOC increased significantly over baseline during the exercise (+62.3% and +63.6%, respectively). HR mean value across the entire Bikram yoga session was 126.6 ± 14.3 bpm reaching a maximum of 168.1 ± 20.2 bpm. SBP was not significantly increased over baseline at any time during the practice with a mean value of 117.0 ± 10.1 mmHg and DBP was significantly decreased over baseline most of the time (-10.1%, mean 71.2 ± 7.3 mmHg) with particular decline toward the end of the practice during the floor postures. DBP during the practice of Bikram yoga was significantly different from that previously reported for nonheated Hatha yoga for normotensive subjects. Further studies evaluating the same group at both conditions are needed to better characterize the magnitude of the changes in HR, SBP, DBP, and MOC.

Elevated myocardial oxygen consumption during cutaneous cold stress in young adult overweight and obese Africans

Exaggerated sympathetic-mediated cardiovascular responses to stressful stimuli (such as cold exposure) has been linked to the development of hypertension and cardiovascular disease, which in turn has been demonstrated to predict the development of future hypertension. The aim of the present study was to test the hypothesis that enhanced change in myocardial oxygen consumption (MVO2) to cutaneous cold stress may be one potential mechanism that predisposes overweight/obese individuals in Africa to developing hypertension. The Rate-Pressure-Product (a non-invasive determinant of MVO2) was measured in normotensive young individuals aged between 18 and 25 years at baseline and during sympathetic activation elicited by cutaneous cold stimulation (CCS). Following CCS, there was a significant enhanced rate pressure product (RPP) change in overweight individuals (P = 0.019). Furthermore, multivariate regression analysis showed that body mass index, but not body weight had a significant influence on RPP variation following CCS. Thus, it can be concluded that normotensive overweight or obese individuals have an exaggerated RPP response to the CCS. However, exposure to cold may augment sympathetic reactivity in overweight/obese individuals, which may contribute to increased risk of developing myocardial dysfunction, even in young normotensive individuals.

Sub-normothermic preservation of donor hearts for transplantation using a novel solution, Somah: A comparative pre-clinical study

Hearts preserved ex vivo at extreme hypothermia (4°C) undergo time-dependent irreversible injury. Our studies using a novel solution, Somah, suggest that hearts are viably preserved at 21°C. In this study we evaluate the relative efficacy of Somah for preservation of hearts at 21°C when compared with the clinically used Celsior and University of Wisconsin (UWS) solutions. Porcine hearts arrested by cardioplegia at 21°C using Somah, Celsior or UWS solution were stored in the respective solutions at 21°C (n = 5) for 5 hours and then reperfused ex vivo for functional assessment. We assessed development of edema, cardiac tissue high-energy phosphate (HEP; ATP + creatine phosphate) levels and release of cardiac enzymes. Alterations in left ventricular wall thicknesses and functional parameters were examined by 2-dimensional (2D) echocardiography. Changes in myocardial oxygen consumption (MVO2) and lactate utilization were assessed at reperfusion. Heart weights were unaltered during 5-hour storage in all groups. After storage, HEP levels were 28.33 ± 5.51, 10.20 ± 2.78 and 5.92 ± 1.46 nmol/liter per milligram protein (p < 0.001) in the Somah, Celsior and UWS group hearts, respectively. Upon reanimation, 2D echocardiography showed edema in the Celsior and UWS hearts; prompt attainment of physiologic function was associated with rapid establishment of aerobic metabolism not requiring stimulatory interventions in the Somah hearts, but not in the Celsior/UWS hearts. Percent fractional area change, ejection fraction and stroke volume were significantly higher (p < 0.001) in Somah hearts than in Celsior and UWS group hearts. Increased synthesis of HEP, rapid metabolic switch and optimal function together provide evidence that hearts procured for transplantation are preserved in a superior viable condition at 21°C with Somah, but not with other commonly used clinical preservation solutions.

Hibiscus sabdariffa L. drink improves postural stress-induced myocardial oxygen consumption changes in young adult men and women

Aim: We hypothesized that Hibiscus sabdariffa drink would affect pressor and myocardial oxygen consumption (MVO 2 ) responses induced by postural stress in young healthy volunteers, and that the impact would be stronger in women than men. Materials and Methods: In a randomized, controlled, cross-over study, 25 young healthy male and 25 female subjects (18-27 years) drank nothing (control), water (500 ml; vehicle) or H. sabdariffa (1.4% w/v) 30 min before standing on three separate days of appointment. We measured supine and standing brachial blood pressure and heart rate (HR). MVO 2 was also estimated by the rate-pressure product (RPP). Results: Increases in systolic blood pressure (SBP) and RPP induced by standing when nothing or water was drunk was significantly larger (P < 0.05) than when H. sabdariffa drink was taken in both male and female subjects. However, H. sabdariffa drink had a stronger (P < 0.05) effect on SBP in women than in men, whereas the effect on RPP was stronger (P < 0.05) in men. Increases in diastolic blood pressure (DBP) and HR induced by standing when water was drunk were significantly larger than when H. sabdariffa drink was ingested in men. Conversely, increase in DBP induced by standing during water ingestion was not significantly attenuated by H. sabdariffa drink in women. Conclusion: The findings in the present study indicate H. sabdariffa drink impacts positively on the heart by reducing its demand for O 2 during postural stress, with a stronger effect in men relatively to women. This may be an important dietary intervention in preventing the development of cardiac dysfunctions among young individuals.

Change in myocardial oxygen consumption employing continuous-flow LVAD with cardiac beat synchronizing system, in acute ischemic heart failure models

Aiming the 'Bridge to Recovery' course, we have developed a novel left ventricular assist device (LVAD) controlling system. It can change the rotational speed of the continuous flow LVAD, EVAHEART, synchronized with the cardiac beat. Employing this system, we have already demonstrated that myocardial oxygen consumption (MVO2), which is considered to be equivalent to native heart load, changes in the hearts of normal goats. Herein, we examined changes in goats with acute ischemic heart failure. We studied 14 goats (56.1±6.9kg) with acute ischemic heart failure due to coronary microsphere embolization. We installed the EVAHEART and drive in four modes: "circuit-clamp", "continuous support", "counter-pulse", and "co-pulse", with 50 and 100% bypass. In comparison to the circuit-clamp mode, MVO2 was reduced to 70.4±17.9% in the counter-pulse mode and increased to 90.3±14.5% in the co-pulse mode, whereas it was 80.0±14.5% in the continuous mode, with 100% bypass (p<0.05). The same difference was confirmed with 50% bypass. This means that we may have a chance to change the native heart load by controlling the LVAD rotation in synchrony with the cardiac rhythm, so we named our controller as the Native Heart Load Control System (NHLCS). Employing changeable MVO2 with NHLCS according to the patient's condition may provide more opportunity for native heart recovery with LVAD, especially for patients with ischemic heart diseases.

Dynamic changes of myocardial oxygen consumption at pacing increased heart rate – the first observation by the continuous measurement of systemic oxygen consumption

Objectives. To assess dynamic changes in myocardial oxygen consumption (myoVO2) during atrial pacing increased heart rate by continuous measurement of systemic oxygen consumption (sysVO2). Methods. Six mechanically ventilated pigs were atrially paced to increase heart rate from baseline 98 ± 9 to 120-140-160-180 bpm for 10 minutes at each stage, with 10 minute intervals without pacing between stages. sysVO2 was continuously measured with a respiratory mass spectrometer. Left anterior descending coronary arterial flow, aorta and coronary sinus blood gases were measured to calculate index of whole heart myoVO2. Results. sysVO2 peaked at the initiation of pacing in the first two to three minutes, followed by a decrease and subsequent stabilization. As heart rate increased, sysVO2 increased by 0.08 ± 0.06 ml/kg/min, 0.14 ± 0.05 ml/kg/min and 0.17 ± 0.10 ml/kg/min, representing a 1.2 ± 0.9%, 2.1 ± 0.7% and 3.0 ± 1.8% increase of sysVO2 respectively; myoVO2 increased by 0.16 ± 0.12 to 0.31 ± 0.14 to 0.36 ± 0.24 ml/100 g/min, representing a 11 ± 9%, 21 ± 9% and 26 ± 12% increase of myoVO2, respectively. The absolute and relative increases in sysVO2 were significantly correlated with the increases in myoVO2. Conclusions. On-line continuous sysVO2 monitoring by respiratory mass spectrometry allows non-invasive assessments of dynamic changes in myoVO2 in vivo. The mechanism for the peaked increase in sysVO2 at the initiation of pacing remains to be explored.

SHA 007. Calisthenic exercise-induced changes in myocardial oxygen consumption in normotensive healthy subjects

SHA 007. Calisthenic exercise-induced changes in myocardial oxygen consumption in normotensive healthy subjects

Cardiac resynchronization therapy; the importance of evaluating cardiac metabolism

Cardiac resynchronization therapy; the importance of evaluating cardiac metabolism

Changes of myocardial oxygen consumption during the course of defecation for patients with acute myocardial infarction

急性心肌梗死(acute myocardial infarction,AMI)早期患者并发症的发生率很高,排便困难是AMI早期发生严重并发症的常见诱因.有报道[1],AMI后2～3d有5.3%的患者在排便过程中出现心绞痛、二次AMI、心力衰竭、猝死等并发症.即使无便秘的AMI患者,在排便时或排便后也有发生意外的可能.可见,排便活动是威胁AMI早期患者生命安全的一大难题。

Preserved myocardial energetics in acute ischemic left ventricular failure -- studies in an experimental pig model.

We hypothesised that acute ischemic left ventricular failure is characterised by depressed systolic and diastolic function combined with inefficiency in oxygen to mechanical work energy transfer. Eight anaesthetised pigs (32+/-3 kg) were employed in an in vivo open chest model. Intraventricular combined pressure and conductance catheters were used to generate continuous left ventricular pressure-volume relations. Myocardial oxygen consumption (MVO(2)) was determined from coronary flow and coronary arteriovenous oxygen difference. After baseline measurements, ischemia was induced by repeated left coronary injections of 50 microm polystyrene microspheres until stroke volume was reduced by 30%. Haemodynamic and biochemical measurements were repeated 30, 90 and 150 min after microembolisation. Coronary embolisation induced a significant reduction in stroke work (2749+/-504-1473+/-449 mmHg ml, P<0.05) at 30 min compared to baseline. Post-embolic contractility was reduced measured by the slope of the preload recruitable stroke work index (66.2+/-12.8-50.0+/-5.8 mmHg, P<0.05) and the slope of the curvilinearly fitted end-systolic pressure-volume relation in V(0) (7.1+/-2.2-4.9+/-2.2 mmHg/ml, P<0.05). The dP/dt(min) decreased (2076+/-291-1468+/-266 mmHg/s, P<0.05), but there was no significant change in diastolic stiffness or Tau. Following the 30 min measurements, there were only small changes in most indices. We found no change in myocardial oxygen consumption for basal metabolic processes or excitation-contraction coupling (unloaded MVO(2)), and there were no changes in conversion of oxygen to total mechanical work (MVO(2)-PVA slope). However, decreased mechanical efficiency (SW/MVO(2)) paralleled an increased ratio of arterial elastance to ventricular elastance. Coronary microembolisation in pigs induce a stable ischemic left ventricular failure characterised by reduced contractility and minimally impaired diastolic function. In this acute ischemic left ventricular failure, the main contributor to all over cardiovascular inefficiency is increased ratio of arterial- to ventricular elastance, a setting that impairs mechanical efficiency. However, efficiency of oxygen to total mechanical work transfer in the myocardium is unaltered. The mechanism behind this finding is elusive and warrants further investigation.

Dobutamine-induced stress with flow restriction causes marked lactate production despite no change in myocardial oxygen consumption or fatty acid uptake

Dobutamine-induced stress with flow restriction causes marked lactate production despite no change in myocardial oxygen consumption or fatty acid uptake

Role of Nitric Oxide in Regulation of Coronary Blood Flow in Response to Increased Metabolic Demand in Dogs With Pacing-Induced Heart Failure.

The role of endothelium-derived nitric oxide (NO) in the metabolic control of coronary blood flow (CBF) in heart failure (HF) is poorly understood, so the present study investigated the effects of inhibitors of NO synthesis on the response of CBF to changes in myocardial oxygen consumption (MVO2) in dogs with HF produced by rapid ventricular pacing and in control dogs. The CBF, MVO2, and other hemodynamic parameters were measured in anesthetized animals. Before infusion of Nomega-nitro-L-arginine methyl ester (L-NAME), the increases in CBF and MVO2 during pacing tachycardia were not significantly different between the control and HF dogs. Intracoronary infusion of L-NAME did not alter the responses of CBF or MVO2 to pacing tachycardia in the control dogs, but in the HF dogs, it reduced the CBF response to pacing tachycardia without altering the tachycardia-induced changes in MVO2. Intracoronary infusion of L-arginine reversed the effect of L-NAME. These results suggest that in HF dogs NO contributes to the regulation of CBF in response to an increased metabolic demand.

Comparison of myocardial oxygen consumption using 11C acetate positron emission tomography scanning in a working and non-working heart transplant model.

In acute cardiac rejection, changes in myocardial oxygen consumption occur; non-invasive detection of these metabolic changes would have obvious clinical utility. In the classic cervical, heterotopic, canine, transplant model, the heart is non-working. It has a low myocardial oxygen consumption. Creation of a working model with normal myocardial oxygen consumption would enhance validity of non-human studies. Clearance of 11C acetate was determined by positron emission tomography (PET) scanning and compared with myocardial oxygen consumption in normal and transplanted canine hearts. Donor hearts from mongrel dogs (2.5-3 kg; n=4) were transplanted into the neck of adult beagles (12-15 kg; n=4), no immunosuppression was given. Two non-working hearts were modified to eject only coronary flow via the right ventricle. In two hearts, a novel working model was created with aortic regurgitation to load the left ventricle. Working and non-working hearts underwent PET scanning on post-operative days 2 and 4. Normal dog hearts (n=2) and native hearts of transplanted dogs (n=3) were used to validate the scanning technique. Coronary sinus and aortic oxygen saturation data along with myocardial blood flow (radiolabeled microspheres) confirmed that clearance of 11C acetate in normal and transplanted hearts followed a bi-exponential model. Myocardial oxygen consumption was correlated with the rate constant of 11C acetate rapid phase clearance (r=0.91) in normal and transplanted hearts. The working hearts had increased myocardial oxygen consumption compared to non-working hearts. This study (1) introduces a model of a working heterotopic cardiac transplantation with near-normal oxygen consumption; and (2) demonstrates that regional myocardial oxygen consumption in transplanted hearts can be detected by 11C acetate PET.

Acute dose-response, double-blind, placebo-controlled pilot study of lercanidipine in patients with angina pectoris

Abstract Objective The aim of this double-blind, placebo-controlled, parallel-group, dose-response, pilot study was to assess the acute hemodynamic and therapeutic effects of a single dose of lercanidipine in patients with angina pectoris. Background The calcium channel blocker lercanidipine is a new lipophilic, vasoselective dihydropyridine derivative with a slow onset and long duration of action that has been shown to be effective in hypertensive patients at a dosage of 10 to 20 mg/d. Methods Forty-five patients (42 males, 3 females) with chronic stable angina pectoris and angiographically documented coronary artery disease received a single oral dose of lercanidipine 5 mg (n = 7), 10 mg (n = 8), 20 mg (n = 7), 30 mg (n = 7), or 40 mg (n = 8) or of placebo (n = 8). Anti-ischemic and antianginal efficacy was assessed by a bicycle exercise test 3 and 8 hours after dosing. Systolic and diastolic blood pressures and heart rate were assessed both at rest and during exercise. Results Because of the small number of patients and high variability between the groups, no significant difference was seen compared with placebo. Nevertheless, a significant ( P Conclusions Our data indicated that the acute administration of lercanidipine 10 mg to 40 mg in patients with stable exercise-induced angina pectoris caused no unfavorable change in myocardial oxygen consumption and was well tolerated.

A critical appraisal of the rate pressure product as index of myocardial oxygen consumption for the study of metabolic coronary flow regulation

For the assessment of metabolic coronary vasodilatation, changes in systolic rate pressure product (RPP) are frequently used to estimate the pacing- or exercise induced changes in myocardial oxygen consumption (MVO2). The present study was designed to test whether this is justified in patients with coronary artery disease. To study the relation between RPP and changes in MVO2 under different conditions, we used data from 21 patients who participated in two previous studies investigating the effect of nitroglycerin (NTG) and anaesthesia on metabolic coronary flow regulation. At control, during administration of NTG 1 μg/kg/min (n=11), and during anaesthesia (n=10), coronary sinus blood flow, MVO2 and RPP were measured at sinus rhythm and during atrial pacing (30 bpm above sinus rate) and the relation between the percentage increase in RPP (Δ%RPP) and MVO2 (Δ%MVO2) was analysed, using standard linear regression analysis. Although a significant relation between Δ%MVO2 and Δ%RPP was found at control and during anaesthesia, prediction intervals were very wide and only 40% and 60% of the variation in Δ%MVO2, respectively, could be explained by the variation in Δ%RPP. During administration of NTG 1 μg/kg/min no significant relation was found between Δ%MVO2 and Δ%RPP. Thus, for the study of metabolic coronary flow regulation, pacing induced changes in MVO2 cannot be predicted accurately from changes in RPP.