scholarly journals Synergistic Effects between Phosphorylation of Phospholamban and Troponin I Promote Relaxation at Higher Heart Rate

2011 ◽  
Vol 2011 ◽  
pp. 1-10
Author(s):  
Lin Zhang ◽  
Yuan Yu ◽  
Zhen Song ◽  
Yun-Ying Wang ◽  
Zhi-Bin Yu
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Function ◽  
Troponin I ◽  
Synergistic Effects ◽  
Stimulation Frequency ◽  
Diastolic Filling ◽  
Relaxant Effect ◽  
Heart Rates ◽  
Working Heart

We hypothesized that the extent of frequency-dependent acceleration of relaxation (FDAR) would be less than that of isoproterenol-(ISO-)dependent acceleration of relaxation (IDAR) at the same increment of heart rates, and ISO may improve FDAR. Cardiac function and phosphorylation of PLB and cTnI were compared in pacing, ISO treatment, and combined pacing and ISO treatment in isolated working heart. The increase in cardiac output and the degree of relaxation was less in pacing than in ISO treatment at the same increment of heart rates. The increasing stimulation frequency induced more significant relaxant effect in ISO perfusion than that in physiological salt perfusion. The pacing only phosphorylated PLB at Thr17, but ISO induced phosphorylation of cTnI and PLB at Ser16 and Thr17. Those results suggest that the synergistic effects of PLB and cTnI induce higher degree of relaxation which makes a sufficient diastolic filling of the ventricle at higher heart rate.

Use of the cardiopulmonary flow index to evaluate cardiac function in Thoroughbred horses

1991 ◽  
Vol 62 (2) ◽  
pp. 43-47 ◽  
Author(s):  
A. J. Guthrie ◽  
Valerie M. Killeen ◽  
Maria S.G. Mülders ◽  
J. F.W. Grosskopf
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Function ◽  
Cardiac Disease ◽  
Clinical Signs ◽  
Simultaneous Recording ◽  
Flow Index ◽  
Heart Rates ◽  
Thoroughbred Horses ◽  
The Mean

The ratio of the cardiopulmonary blood volume to stroke volume is called the cardiopulmonary flow index (CPFI). The CPFI can be determined indirectly from the simultaneous recording of a radio cardiogram and an electrocardiogram. The CPFI and cardiac output were measured simultaneously in horses (n = 10) that were diagnosed as having cardiac disease. The diseased subjects were probably all exposed to feed contaminated with the ionophore, salinomycin, and all showed clinical signs indicative of chronic toxic myocarditis. The results obtained from these subjects were compared with those from control animals and significant differences (P 0,05) were found between the mean CPFI of the control horses and those with macroscopically visible myocardial fibrosis on post mortem examination. No significant differences were found between the means of the cardiac output measured in either of the groups of horses. The effect of pharmacological acceleration of the heart rate on the CPFI was also studied. Significant differences (P 0,05) were found between the mean CPFI and the slopes of the regression lines of CPFI on heart rate of the control and principal groups of horses. These differences were greatest at heart rates near to the resting heart rates of the individuals. The CPFI was found to be a more sensitive measure of cardiac function than cardiac output, in the horses.

Anticipatory, exercise, and recovery heart rates of girls as affected by four running events

1964 ◽  
Vol 19 (5) ◽  
pp. 853-856 ◽  
Author(s):  
Vera Skubic ◽  
Jane Hilgendorf
Keyword(s):  
Heart Rate ◽  
Cardiac Function ◽  
Heart Rate Response ◽  
Heart Rates

The heart rate response to running various distances was studied using five highly trained girls as subjects. A telemetering instrument was employed so that the testing could be done under actual sport conditions. The findings indicated that 1) the anticipatory heart rate just prior to exercise represented 59% of the total adjustment to exercise, 2) the heart rates during exercise were 2.5 times the resting values, and 3) heart rates observed at the end of the 220-, 440-, 880-yard, and mile events were simila cardiac function; exercise Submitted on October 22, 1963

scholarly journals Comparison of different Parameters of Heart Rate Frequency of Tasks Performed during Aircraft Open-Basket Ground Deicing Activities

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Landau K
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Field Study ◽  
Small Sample Size ◽  
Field Studies ◽  
Small Sample ◽  
Upper Body ◽  
Evaluation Measure ◽  
Cardiac Cost ◽  
Working Heart

Plane deicing is mandatory to insure safe plane take-off. Previous human factors studies have shown that open-basket deicing activity can be improved. The objective of the paper is to compare heart rate assessment models within a field study with numerous influencing variables and small sample size as well as to deepen our understanding of the most demanding openbasket tasks using cardiac output. A field study in a Canadian centered plane deicing facility was conducted in 2016-2017. 12 participants contributed to a thorough description and analysis of open-basket deicing activities. Respiratory and cardiac output of these participants was collected using Hexoskin vests. Working heart rate, heart rate reserves as well as calculations of absolute cardiac cost were done. Working heart rate (WHR), Heart Rate Reserve (HRR) and Absolute Cardiac Cost (ACC) do not behave uniformly for the majority of participants. In field studies with a large number of influencing variables on the heart rate, it is usually not sufficient to consider one single evaluation measure like WHR. In the interest of protecting employees, it seems to make sense to use the more cautious measures HRR or ACC as parameters instead of WHR. Superimposed activities (e.g. forced postures and dynamic use of upper body) have a significant effect on heart rate increases. In 8 out of 11 cases we have fatigue-related increases in heart rate over the observation period. Similar studies need to be conducted in other aircraft deicing facilities.

Pulsatile Flow Characteristics in a Stenotic Aortic Valve Model: An In Vitro Experimental Study

2019 ◽  
Author(s):  
Ruihang Zhang ◽  
Yan Zhang
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Aortic Valve ◽  
Pulsatile Flow ◽  
Heart Diseases ◽  
Flow Characteristics ◽  
Aortic Valve Area ◽  
Heart Rates ◽  
Valvular Heart Diseases

Abstract Aortic stenosis (AS) is one of the most common valvular heart diseases around the globe. The accurate assessment of AS severity is important and strongly associated with accurate interpretation of the hemodynamic parameters across the stenotic valve. In this study, we conducted in vitro fluid dynamic experiments to investigate the pulsatile flow characteristics of a stenotic aortic valve as a function of heart rate. An in vitro cardiovascular flow simulator was used to generate pulsatile flow with a prescribed waveform (40% systolic period and 4L/min cardiac output) under varied heart rates (50 bpm, 75 bpm and 100 bpm). The stenotic valve was constructed by molding silicone into three-leaflet aortic valve geometries wrapping around thin fabrics which increases its stiffness and tensile strength. Two-dimensional phase-locked particle image velocimetry (PIV) was employed to quantify the flow field characteristics of the stenotic valve. Pressure waveforms were recorded to evaluate the severity of the stenosis via the Gorlin and Hakki equations. Results suggest that as the heart rate increases, the peak pressure gradient across the stenotic aortic valve increases significantly under the same cardiac output. Analysis also shows the estimated aortic valve area (AVA) decreases as the heart rate increases under the same cardiac output using Gorlin equation estimation, while the trend is reversed using Hakki equation estimation. Under phase-locked conditions, quantitative flow characteristics, such as phase-averaged flow velocity, turbulence kinetic energy (TKE) for the stenotic aortic valve were analyzed based on the PIV data. Results suggest that the peak systolic jet velocity downstream of the valve increases as the heart rate increases, implying a longer pressure recovery distance as heart rate increases. While the turbulence at peak systole is higher under the slower heart rate, the faster heart rate contributes to a higher turbulence during the late systole and early diastole phases. Based on the comparison with no-valve cases, the differences in TKE was mainly related to the dynamics of leaflets under different heart rates. Overall, the results obtained in this study demonstrate that the hemodynamics of a stenotic aortic valve is complex and the assessment of AS could be significantly affected by the pulsating rate of the flow.

scholarly journals CARDIAC FUNCTION DURING MINI-INVASIVE REPAIR OF PECTUS EXCAVATUM WITH THE NUSS PROCEDURE

2021 ◽  
Vol 74 (8) ◽  
pp. 1809-1815
Author(s):  
Ulbolhan A. Fesenko ◽  
Ivan Myhal
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Index ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Epidural Anaesthesia ◽  
Pectus Excavatum ◽  
Stroke Volume Index ◽  
Volume Index ◽  
Nuss Procedure

The aim of the study was to analyze cardiac function during Nuss procedure under the combination of general anesthesia with different variants of the regional block. Materials and methods: The observative prospective study included 60 adolescents (boys/girls=47/13) undergone Nuss procedure for pectus excavatum correction under the combination of general anaesthesia and regional blocks. The patients were randomized into three groups (n=20 in each) according to the perioperative regional analgesia technique: standart epidural anaesthesia (SEA), high epidural anaesthesia (HEA) and bilateral paravertebral anaesthesia (PVA). The following parameters of cardiac function were analyzed: heart rate, estimated cardiac output (esCCO), cardiac index (esCCI), stroke volume (esSV) and stroke volume index (esSVI) using non-invasive monitoring. Results: Induction of anesthesia and regional blocks led to a significant decrease in esCCO (-9.4%) and esCCI (-9.8%), while esSV and esSVI remained almost unchanged in all groups (H=4.9; p=0.09). At this stage, the decrease in cardiac output was mainly due to decreased heart rate. At the stage of sternal elevation we found an increase in esSV, which was more pronounced in the groups of epidural blocks (+23.1% in HEA and +18.5% in SEA). After awakening from anesthesia and tracheal extubation esSV was by 11% higher than before surgery without ingergroup difference. Conclusions: The Nuss procedure for pectus excavatum correction lead to improved cardiac function. increase in stroke volume and its index were more informative than cardiac output and cardiac index which are dependent on heart rate that is under the influence of anaesthesia technique.

scholarly journals Hemodynamic Consequence of Different Pacing Modes after Aortic Valve Replacement

2018 ◽  
Vol 21 (2) ◽  
pp. 090
Author(s):  
Arndt H Kiessling
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Aortic Valve ◽  
Left Ventricular Hypertrophy ◽  
Aortic Valve Replacement ◽  
Diastolic Function ◽  
Valve Replacement ◽  
Ventricular Hypertrophy ◽  
Left Ventricular ◽  
Heart Rates

Objectives: Ventricular pacemaker stimulation may cause deterioration of hemodynamics in patients with left-ventricular hypertrophy following aortic valve replacement. Since the diastolic function is often impaired, it remains unclear which heart rate best optimizes cardiac output. Low heart rates are suggested to treat impaired diastolic function chronically, but it is possible that cardiac output may be augmented by increasing the heart rate in patients with a fixed stroke volume (SV). The aim of this study is the identification of the best pacing mode and heart rate for the surrogate parameter SV and cardiac index(CI) in patients with left ventricular hypertrophy.Methods: Various pacemaker stimulation modes and different heart rates, as well as their influence on hemodynamics, were tested following aortic valve replacement in 48 patients with severe left-ventricular hypertrophy (Intraventricular septum (IVS)>1.5 cm) and aortic stenosis. SV and cardiac output were recorded by pulse curve analysis. Four modes of stimulation (right ventricular pacemaker stimulation (DDDright), left ventricular pacemaker stimulation (DDDleft), biventricular pacemaker stimulation (DDDbi), atrial pacemaker stimulation (AAI)) were documented at five different rates (60, 80, 100, 120, 140 beats/min) and three different postoperative time points (intraoperatively, 3h and 24h postoperatively).Results: The highest CI was found at linear rates between 60 to 140bpm. AAI was the best mode of stimulation in the majority of cases (35%), but in others, either left, right and/or biventricular stimulation was found to be better (15%). SV showed a u-shaped trend with a peak at 100 beats/min.Conclusion: An increase in the heart rate does not lead to a notable drop in SV postoperatively in left-ventricular hypertrophy; hence a rise in cardiac output can be anticipated up to a rate of 100 beats/min. A standardized response in terms of an ideal pacemaker stimulation mode could not be identified.

Cardiac function is not significantly diminished in hearts isolated from young caveolin-1 knockout mice

2010 ◽  
Vol 299 (4) ◽  
pp. H1183-H1189 ◽  
Author(s):  
Ava K. Chow ◽  
Edwin E. Daniel ◽  
Richard Schulz
Keyword(s):  
Heart Rate ◽  
Cardiac Function ◽  
Troponin I ◽  
Ischemia Reperfusion ◽  
Systolic Pressure ◽  
Wild Type ◽  
Stress Injury ◽  
Caveolin 1 ◽  
Myocardial Oxidative Stress

Matrix metalloproteinases (MMPs) are known to degrade components of the extracellular matrix. More recently, in myocardial oxidative stress injury including ischemia-reperfusion, MMP-2 is activated and degrades troponin I and α-actinin. MMP activity is regulated at several levels. We recently showed that MMP-2 is localized in the caveolae of cardiomyocytes and is negatively regulated by caveolin-1 (Cav-1). The caveolin scaffolding domain of Cav-1 inhibits MMP-2 proteolytic activity in vitro, and Cav-1−/− mouse hearts have increased MMP-2 activity compared with controls. Whether this increase in MMP-2 activity translates to impaired cardiac function is unknown. Hearts isolated from Cav-1−/− mice and their wild-type controls were perfused as isolated working hearts and physiologically challenged with increasing increments of left atrial preload (7–22.5 mmHg). The hearts were then pharmacologically challenged with increasing concentrations of isoproterenol (0.1–100 nM). Functionally, the Cav-1−/− hearts were similar to the controls in heart rate, peak systolic pressure, developed pressure, and rate pressure product. At higher preload pressures, the Cav-1−/− hearts outperformed the control hearts. Coronary flow was significantly higher in Cav-1−/− hearts under all conditions. The highest concentration of isoproternol increased the heart rate of Cav-1−/− hearts more than in controls. Western blot analysis revealed no significant changes in troponin I or α-actinin between Cav-1−/− hearts and their controls. There was a significant loss of MMP-2 from both knockout and control hearts during the perfusion. In summary, despite the loss of Cav-1, Cav-1−/− hearts show similar or better cardiac function compared with wild-type hearts following physiological challenge or β-adrenergic stimulation in vitro, and this appears unrelated to changes in MMP-2.

scholarly journals Reconsideration of heart rate-cardiac output relationships and resting cardiac function in patients with brady-arrhythmias.

1984 ◽  
Vol 25 (5) ◽  
pp. 713-723 ◽  
Author(s):  
Masuaki FUJIYAMA ◽  
Yoh-ichiro FURUTA ◽  
Akihiro TANABE ◽  
Jun MATSUMURA ◽  
Jun OHBAYASHI ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Function

Lactic Acidosis and the Cardiovascular System in the Dog

1983 ◽  
Vol 64 (6) ◽  
pp. 573-580 ◽  
Author(s):  
Allen I. Arieff ◽  
Edward W. Gertz ◽  
Robert Park ◽  
Will Leach ◽  
Virginia C. Lazarowitz
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Lactic Acid ◽  
Lactic Acidosis ◽  
Cardiac Function ◽  
Myocardial Dysfunction ◽  
Left Ventricular ◽  
Control Group ◽  
Type B

1. Lactic acidosis is a clinical syndrome characterized by metabolic acidaemia (pH < 7.25) and hyperlactaemia (lactate >5 mmol/l). Many patients with type B lactic acidosis have no evidence of tissue hypoxia or myocardial dysfunction when first evaluated. Although it is considered that cardiac dysfunction is secondary to the systemic effects of lactic acidosis, the reverse may sometimes be true. To evaluate this possibility, studies were carried out in 43 dogs consisting of a control group and three groups which had hyperlactataemia and metabolic acidaemia related to either: (1) phenformin infusion; (2) hepatectomy; (3) lactic acid infusion. Serial studies of cardiac function, as well as measurements of GFR (glomerular filtration rate) and hepatic portal vein (HPV) blood flow, were carried out. 2. in dogs infused with phenformin for 99 min, the arterial pH, lactate, bicarbonate, heart rate and mean blood pressure (BP) were normal. However, there was significant deterioration (P < 0.01) in several indices of cardiac function, including the peak positive dP/dt, cardiac output, LVEDP (left ventricular end-diastolic pressure) and percentage extraction of oxygen and lactate by the heart. After 3 h of phenformin, the blood lactate exceeded 5 mmol/l and there were further significant decrements (P < 0.01) in cardiac output, LVEDP and dP/dt, as well as BP and heart rate. in dogs subjected to hepatectomy, the decrement in cardiac output was similar to that with phenformin infusion. However, in animals infused with lactic acid, despite a similar blood pH and lactate, cardiac output was unaffected. Although percentage myocardial oxygen extraction declined in phenformin-infused animals, there was a concomitant increase in coronary sinus blood flow such that myocardial oxygen utilization was probably unaltered. 3. Thus, in certain types of experimental type B lactic acidosis, myocardial dysfunction may be a primary event, with other associated systemic manifestations being secondary.

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