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Effects of 7 wk of training on basal (open bars) and insulinstimulated (solid bars) mitogen-activated protein kinase kinase (MEK1) activity (dpm 10 5 per unit protein per 20 min) in gastrocnemius muscle from Zucker rats who underwent hindlimb perfusion. Untrained lean Zucker rats (n 8) served as controls. Untrained fatty rats (n 8) and groups of fatty rats that had been trained for 7 wk and then detrained for 24 or 96 h or 7 days (n 7 each) were compared. Values are means SE. Gastrocnemii from the control insulin-stimulated leg were homogenized and immunoprecipitated with an anti-MEK1 antibody, and activity assays were performed as described in the text. a, P 0.05 vs. lean Zucker rats; d, P 0.01 vs. untrained fatty rats.
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Resting cardiac function is a poor indicator of functional cardiac reserve that is invoked during exercise. The objective of this study was to investigate the relationship between functional cardiac reserve and systemic vascular resistance (SVR) using an ambulatory radionuclide monitoring system (the Vest system) in patients with heart disease. The...
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... and Tyr-185 residues (32). Therefore, we determined whether exercise training increases MEK1 activity or alters its response to insulin in rat hindlimb muscle. MEK1 activity was assayed in muscle protein by measur- ing the ability of MEK1 immune complexes to phosphor- ylate a recombinant kinase-inactive MAPK (p42 MAPK ). The results are shown in Fig. 3. Although ERK2 activity was significantly reduced in the obese rats, MEK1 activ- ity was not reduced significantly, either basally or after insulin stimulation. Exercise training significantly in- creased insulin-stimulated, but not basal, MEK1 activity. Twenty-four hours after the last training session, insulin- stimulated MEK 1 ...
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Peak oxygen uptake (VO(2)) testing is commonly used to assess chronic heart failure (CHF) patients' exercise tolerance. The test requires maximal effort; however, many participants have low confidence (self-efficacy) to perform optimally.
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Objective:
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Methods:
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Citations
... A significant decrease in SVR has already been shown to be the predominant mechanism by which the EF increases during exercise in heart disease patients (23), and during the months following a myocardial infarction (13). A vasodilatorrelated decrease in SVR was additionally shown to be associated with proportional increases in stroke volume and cardiac output of heart failure patients (24). ...
Introduction: This cardiovascular magnetic resonance (CMR) study aims to determine whether changes in systemic vascular resistance (SVR), obtained from CMR flow sequences, might explain the significant long-term changes in left ventricular (LV) ejection fraction (EF) observed in subjects with no cardiac disease history.
Methods: Cohort subjects without any known cardiac disease but with high rates of hypertension and obesity, underwent CMR with phase-contrast sequences both at baseline and at a median follow-up of 5.2 years. Longitudinal changes in EF were analyzed for any concomitant changes in blood pressure and vascular function, notably the indexed SVR given by the formula: mean brachial blood pressure / cardiac output x body surface area.
Results: A total of 118 subjects (53 ± 12 years, 52% women) were included, 26% had hypertension, and 52% were obese. Eighteen (15%) had significant EF variations between baseline and follow-up (7 increased EF and 11 decreased EF). Longitudinal changes in EF were inversely related to concomitant changes in mean and diastolic blood pressures ( p = 0.030 and p = 0.027, respectively) and much more significantly to SVR ( p < 0.001). On average, these SVR changes were −8.08 ± 9.21 and +8.14 ± 8.28 mmHg.min.m ² .L ⁻¹ , respectively, in subjects with significant increases and decreases in EF, and 3.32 ± 7.53 mmHg.min.m ² .L ⁻¹ in subjects with a stable EF (overall p < 0.001).
Conclusions: Significant EF variations are not uncommon during the long-term CMR follow-up of populations with no evident health issues except for uncomplicated hypertension and obesity. However, most of these variations are linked to SVR changes and may therefore be unrelated to any intrinsic change in LV contractility. This underscores the benefits of specifically assessing LV afterload when EF is monitored in populations at risk of vascular dysfunction.
Clinical Trial Registration: ClinicalTrials.gov , identifier: NCT01716819 and NCT02430805.
... A signi cant decrease in SVR has already been shown to be the main mechanism by which the EF increases during exercise in heart disease patients 25 , and during the months following a myocardial infarction 11 . The observation of a frequent decrease in SVR after infarction, has been attributed to the introduction of a vasodilator medical regimen (i.e., Angiotensin Converting Enzyme Inhibitors or Angiotensin Receptor Blockers) 11 . ...
This study aims to determine whether changes in vascular function parameters, such as systemic vascular resistance (SVR), might explain the significant changes in LV ejection fraction (EF) that may be observed over the long term in subjects with no evident health issues.
Subjects with no evident health issues except for hypertension and obesity, underwent MRI with phase-contrast sequences at baseline and at a median follow-up of 5.2 years. Longitudinal changes in EF were analyzed with regard to concomitant changes in the vascular function parameters computed with an MRI flow-sequence.
A total of 118 subjects (53±12 years) were included among whom, 52% were women, 26% had hypertension, and 52 % were obese. The longitudinal change in EF was inversely related to concomitant changes in mean and diastolic blood pressure (p=0.030 and p=0.027, respectively) and much more significantly so, in SVR (p<0.001). SVR changes were -8.08±9.21 and +8.14±8.28 mmHg.min.m².L-1 respectively in subjects with significant increases (n=7) and decreases (n=10) in EF, and 3.32±7.53 mmHg.min.m².L-1 in subjects with stable EF (n=100) (overall p<0.001).
The EF variations of populations with no evident health issues, except for hypertension and obesity, are mostly driven by concomitant changes in arterial function rather than in LV contractility.
Clinical Trial Registrations. NCT01716819 and NCT02430805 on the ClinicalTrials.gov site.
... The ST/HR index = (Peak exercise -upright control ST)/(Peak exercise -upright control HR). The ST/HR index increases the sensitivity for diagnosis of CAD and predicts mortality and cardiovascular events [29, [146][147][148][149]. Data from Kingfield's group [137,142,150] suggest that the ST/HR index should be used in routine EST evaluation. ...
... The ST/HR index = (Peak exercise -upright control ST)/(Peak exercise -upright control HR). The ST/HR index increases the sensitivity for diagnosis of CAD and predicts mortality and cardiovascular events [29, [146][147][148][149]. Data from Kingfield's group [137,142,150] suggest that the ST/HR index should be used in routine EST evaluation. ...
Purpose: The objectives of this review were to: (1) identify the acute cardiovascular responses to aerobic exercise used in an exercise stress test (EST), (2) identify
when and how to best conduct an EST including the stopping point, (3) identify conditions that would preclude an EST, (4) define the limiting signs and symptoms
associated with an EST (5), discuss what data are needed as part of an EST and how to interpret EST data.
Methods: We identify the cardiovascular responses to an EST and when an EST should or should not be used. Finally we analyze the components of an EST and
potential sensitivities, significances and predictability of the changes in the outcome data that will provide diagnosis overt cardiovascular disease, and for purposes of
exercise prescription and evaluation of rehabilitation effects in cardiac patients.
Results: Although most of the focus for performing an EST traditionally has been on the diagnostic value to identify ST-segment abnormalities, an EST provides
other valuable diagnostic and prognostic data including maximal oxygen consumption (predicted or measured), exercise capacity and fatigability, blood pressure and
heart rate responses to exercise and recovery.
Conclusions: This review identifies the most recent standards, and guidelines of EST, which include the acute physiological response of the cardiovascular system to
aerobic exercise, the use of EST in evaluation of coronary artery disease, an updated diagnostic and prognostic variables of EST, and reporting of EST.
Condensed abstract: This review identifies the most recent standards, and guidelines of the exercise stress test (EST), which include the acute physiological response
of the cardiovascular system to aerobic exercise, the use of EST in evaluation of coronary artery disease, diagnostic and prognostic variables of EST, and reporting
of EST.
... Here, for the first time, we describe combining regular ETT with MRI stress testing in mouse models of HF. The MRI stress test allows for an estimate of cardiac reserve: the ability of the heart to improve efficiency and function to meet heightened metabolic demands (2). A loss or reduction in cardiac reserve would, therefore, be expected to translate into exercise intolerance. ...
The loss of cardiac reserve is in part responsible for exercise intolerance in late stage heart failure (HF). Exercise tolerance testing (ETT) has been performed in mouse models of heart failure; however, treadmill performance and at-rest cardiac indices determined by magnetic resonance imaging (MRI) rarely correlate. The current study adopted a stress MRI technique for comparison with ETT in HF models, using isoproterenol (ISO) to evoke cardiac reserve responses. Male C57BL/6J mice were randomly subjected to myocardial infarction (MI), transverse aortic constriction (TAC) or sham surgery under general anesthesia. Mice underwent serial ETT on a graded treadmill with follow-up ISO stress MRI. TAC mice showed consistent exercise intolerance, with a 16.2% reduction in peak oxygen consumption (VO2 max) vs. sham at 15 weeks post-surgery (WPS). MI and sham mice had similar VO2 max from 7 WPS onward. Time to a respiratory exchange ratio of 1.0 correlated with ETT distance (r=0.64; P<0.001). The change in EF under ISO stress was reduced in HF mice at 4WPS (10.1±3.9 Δ% and 8.9±3.5 Δ% in MI and TAC respectively, compared to 32.0±3.5 Δ% in sham; P<0.001). However, cardiac reserve differences between surgery groups were not observed at 16 WPS in terms of ejection fraction or cardiac output. In addition, ETT did not correlate with cardiac indices under ISO stress. In conclusion, ISO stress was unable to reflect consistent differences in ETT between HF and healthy mice, suggesting cardiac-specific indices are not the sole factors in defining exercise intolerance in mouse HF models.
One of the fundamental functions in each intensive care unit is monitoring, while we can consider respiratory monitoring, cardiovascular monitoring, and cerebral monitoring as the main three monitoring functions of ICU. Though, in the current world of increasing health technology, the sophisticated bedside examinations of the clinicians could not be replaced by any of these technologic improvements. On the other hand, continuous hemodynamic assessments after cardiac operations are the cornerstone of postoperative cardiac surgeries. The main cardiovascular monitoring methods involve—but are not confined to—the following pages, though more detailed explanations could be found in details in related texts. Noninvasive and invasive blood pressure, central venous and pulmonary artery pressure, cardiac output monitoring modalities, and the normal range for measured hemodynamic variables are among the main topics that the reader could be familiar with after reading this chapter.
One of the fundamental functions in each intensive care unit is monitoring, while respiratory monitoring, cardiovascular monitoring, and cerebral monitoring are the main three monitoring functions of ICU. In the current world of increasing health technology, though, the exact and sophisticated examinations of the clinicians could not be replaced by any of these technologic improvements. A continual hemodynamic assessment after cardiac operations is a cornerstone of postoperative cardiac surgeries. The main cardiovascular monitoring methods involve – but are not confined to – the following pages, though more detailed explanations could be found in details in related texts. Noninvasive and invasive blood pressure, central venous and pulmonary artery pressure, cardiac output monitoring modalities, and the normal range for measured hemodynamic variables are among the main topics that the reader could be familiar with after reading this chapter.
BACKGROUND: Cardiac reserve indicators obtained under quiescent condition are used as evaluating index for cardiac reserve functions. However, most important aspect of cardiac dysfunction in heart failure is not the depressed cardiac performance noted at basal resting states, but rather the loss of cardiac reserve. OBJECTIVE: To develop a data processing and information management system for detecting cardiac reserve indicator with the widely used B mode ultrasound instrument in the ultrasonography field, and to provide guidance for B mode ultrasound instrument perfection. METHODS: General B mode ultrasound instrument as peripherals was connected with the pc by image acquisition card; ultrasound heart image diagnosis and management system including professional heart image acquisition and process and perfect data bank was develop. RESULTS AND CONCLUSION: An efficient and flexible mini picture archiving and communication system system was achieved, which realized image enhancement, geometric parameter measuring, convenient diagnosis report output, archive management and print function. Results demonstrated that with the powerful data process ability of PC, the system could improve the performance of the traditional ultrasound instrument in detecting cardiac reserve, which provide a powerful support for the further study.
