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Journal of the American College of... Mar 2001The goal of this study was to review the origin, clinical relevance and treatment of pulse pressure (PP). Elevated PP is increasingly being recognized as a risk factor... (Review)
Review
The goal of this study was to review the origin, clinical relevance and treatment of pulse pressure (PP). Elevated PP is increasingly being recognized as a risk factor for cardiovascular, particularly coronary, disease. Pulse pressure is discussed in terms of both Windkessel and distributive models of the arterial circulation. Pulse pressure arises from the interaction of cardiac ejection (stroke volume) and the properties of the arterial circulation. An increased stiffness of the aorta and large arteries leads to an increase in PP through a reduction in arterial compliance and effects on wave reflection. A number of factors are known to influence arterial wall behavior and, therefore, PP. In addition to the effects of aging and blood pressure on arterial wall elasticity, there is some evidence that atherosclerosis, per se, amplifies these effects. Thus, the relationship between PP and coronary disease may be bidirectional. A number of dietary and lifestyle interventions have been shown to modify large artery behavior. These include aerobic exercise training and consumption of n-3 fatty acids. Conversely, strength training is associated with an increase in arterial stiffness and a higher PP. The effects of antihypertensive medication have been extensively studied, but many studies are difficult to interpret because of concomitant change in blood pressure, and to a lesser degree, heart rate. However a number of studies do suggest direct arterial wall effects, particularly for angiotensin-converting enzyme inhibitors. A distributed compliance model of the arterial circulation provides a framework for understanding the causes, effects and potential treatment of elevations in PP.
Topics: Animals; Blood Pressure; Blood Vessels; Cardiovascular Diseases; Cholesterol; Compliance; Diabetes Mellitus; Hemodynamics; Humans; Hypertension; Models, Cardiovascular; Pressure; Pulse; Risk Factors; Stroke Volume
PubMed: 11263624
DOI: 10.1016/s0735-1097(01)01108-1 -
European Journal of Vascular and... Nov 2020Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false...
OBJECTIVE
Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false aneurysm and intimal hyperplasia stenosis onset. Over the last decades, manufacturers have tried to develop substitutes that mechanically mimic arterial properties and avoid a compliance mismatch at the anastomoses in particular. However, data are missing about how initial compliance properties could change with time. The goal of this study was to evaluate how the compliance of vascular grafts evolves under cyclic loading conditions in vitro.
METHODS
The compliance of three different models of commercially available textile polyethylene terephthalate (PET) grafts was evaluated. Tests were performed with and without their original coating. Compliance was assessed with a specific device dedicated to measure the deformations undergone by a graft under cyclic pressure loading conditions, using image analysis software. In each experiment, image analysis was performed under 60 and 140 mmHg pressure loading conditions at loading start (H0) and after three, six, and 24 h (H3, H6, H24) loading time. Average radial, longitudinal, and volumetric compliance was calculated from the obtained images.
RESULTS
Twenty-four samples were tested. Results demonstrate that all values decreased significantly within only a few hours. On average, the loss of compliance after 3 h of cyclic loading ranged on average from 35% for longitudinal compliance to 39% for radial compliance and 37% (p < .050) for volume compliance. After 24 h, the loss of radial, longitudinal and volume compliance was respectively 63 ± 3%, 60.5 ± 2% and 61 ± 7%.
CONCLUSION
In this in vitro model, PET graft compliance has already decreased significantly within 3 h. The rapid loss of compliance identified in this experimental study helps explain the mismatch mentioned in clinical observations.
Topics: Blood Vessel Prosthesis; Compliance; Materials Testing; Polyethylene Terephthalates; Stress, Mechanical; Textiles; Time Factors; Vascular Grafting
PubMed: 32792290
DOI: 10.1016/j.ejvs.2020.07.016 -
Exercise and Sport Sciences Reviews Oct 2014Recent work showed that arterial compliance may be elevated unexpectedly in obese children, attributable to accelerated growth and maturation. We hypothesize that... (Review)
Review
Recent work showed that arterial compliance may be elevated unexpectedly in obese children, attributable to accelerated growth and maturation. We hypothesize that children with obesity or Type 2 diabetes may reach peak arterial maturation earlier in life and then experience an earlier, and potentially more rapid, decline in arterial compliance, leading toward earlier cardiovascular disease development.
Topics: Adolescent; Arteries; Cardiovascular Diseases; Child; Compliance; Diabetes Mellitus, Type 2; Humans; Obesity; Risk Factors
PubMed: 25062003
DOI: 10.1249/JES.0000000000000024 -
Methodist DeBakey Cardiovascular Journal 2015Office-based blood pressure monitoring has been the primary way of managing the cardiovascular risk associated with a diagnosis of hypertension. As research unfolds the... (Review)
Review
Office-based blood pressure monitoring has been the primary way of managing the cardiovascular risk associated with a diagnosis of hypertension. As research unfolds the nature in which the pulse waveform is generated, additional insights beyond standard measures of systolic and diastolic blood pressure have emerged to help reclassify the cardiovascular risk of patients or point out patterns that have, in longitudinal cohort studies, shown promise as predictors of outcomes such as heart failure. In this review, we focus on the pressure profile in the proximal aorta that can be obtained easily and noninvasively from the radial or brachial artery during a clinical office encounter and the potential value of these measures in outcomes such as left ventricular hypertrophy and heart failure.
Topics: Arterial Pressure; Compliance; Humans; Hypertension; Office Visits; Predictive Value of Tests; Prognosis; Pulse; Pulse Wave Analysis; Vascular Stiffness
PubMed: 27057290
DOI: 10.14797/mdcj-11-4-219 -
PloS One 2019Current myoelectric prosthetic limbs are limited in their ability to provide direct sensory feedback to users, which increases attentional demands and reliance on visual...
Current myoelectric prosthetic limbs are limited in their ability to provide direct sensory feedback to users, which increases attentional demands and reliance on visual cues. Vibrotactile sensory substitution (VSS), which can be used to provide sensory feedback in a non-invasive manner has demonstrated some improvement in myoelectric hand control. In this work, we developed and tested two VSS configurations: one with a single burst-rate modulated actuator and another with a spatially distributed array of five coin tactors. We performed a direct comparative assessment of these two VSS configurations with able-bodied subjects to investigate sensory perception, myoelectric control of grasp force and hand aperture with a prosthesis, and the effects of interface compliance. Six subjects completed a sensory perception experiment under a stimulation only paradigm; sixteen subjects completed experiments to compare VSS performance on perception and graded myoelectric control during grasp force and hand aperture tasks; and ten subjects completed experiments to investigate the effect of mechanical compliance of the myoelectric hand on the ability to control grasp force. Results indicated that sensory perception of vibrotactile feedback was not different for the two VSS configurations in the absence of active myoelectric control, but it was better with feedback from the coin tactor array than with the single actuator during myoelectric control of grasp force. Graded myoelectric control of grasp force and hand aperture was better with feedback from the coin tactor array than with the single actuator, and myoelectric control of grasp force was improved with a compliant grasp interface. Further investigations with VSS should focus on the use of coin tactor arrays by subjects with amputation in real-world settings and on improving control of grasp force by increasing the mechanical compliance of the hand.
Topics: Adult; Amputation, Surgical; Amputees; Artificial Limbs; Biomechanical Phenomena; Compliance; Computer Simulation; Electromyography; Feedback, Sensory; Female; Hand; Hand Strength; Humans; Male; Perception; Prosthesis Design; Touch; Vibration; Young Adult
PubMed: 30650161
DOI: 10.1371/journal.pone.0210956 -
Journal of Preventive Medicine and... Jul 2021This study explored changes in individuals' behavior in response to social distancing (SD) levels and the "no gatherings of more than 5 people" (NGM5) rule in Korea...
OBJECTIVES
This study explored changes in individuals' behavior in response to social distancing (SD) levels and the "no gatherings of more than 5 people" (NGM5) rule in Korea during the coronavirus disease 2019 (COVID-19) pandemic.
METHODS
Using survey data from the COVID-19 Behavior Tracker, exploratory factor analysis extracted 3 preventive factors: maintenance of personal hygiene, avoiding going out, and avoiding meeting people. Each factor was used as a dependent variable. The chi-square test was used to compare differences in distributions between categorical variables, while binary logistic regression was performed to identify factors associated with high compliance with measures to prevent transmission.
RESULTS
In men, all 3 factors were significantly associated with lower compliance. Younger age groups were associated with lower compliance with maintenance of personal hygiene and avoiding meeting people. Employment status was significantly associated with avoiding going out and avoiding meeting people. Residence in the capital area was significantly associated with higher compliance with personal hygiene and avoiding venturing out. Increasing SD levels were associated with personal hygiene, avoiding going out, and avoiding meeting people. The NGM5 policy was not significantly associated with compliance.
CONCLUSIONS
SD levels, gender, age, employment status, and region had explanatory power for compliance with non-pharmaceutical interventions (NPIs). Strengthening social campaigns to inspire voluntary compliance with NPIs, especially focused on men, younger people, full-time workers, and residents of the capital area is recommended. Simultaneously, efforts need to be made to segment SD measures into substrategies with detailed guidance at each level.
Topics: Adult; Age Factors; COVID-19; Compliance; Cross-Sectional Studies; Female; Health Policy; Humans; Male; Middle Aged; Physical Distancing; Republic of Korea; Sex Factors; Surveys and Questionnaires; Young Adult
PubMed: 34370935
DOI: 10.3961/jpmph.21.139 -
Biomaterials Science May 2023Small diameter synthetic vascular grafts have high failure rate due to the thrombosis and intimal hyperplasia formation. Compliance mismatch between the synthetic graft...
Small diameter synthetic vascular grafts have high failure rate due to the thrombosis and intimal hyperplasia formation. Compliance mismatch between the synthetic graft and native artery has been speculated to be one of the main causes of intimal hyperplasia. However, changing the compliance of synthetic materials without altering material chemistry remains a challenge. Here, we used poly(vinyl alcohol) (PVA) hydrogel as a graft material due to its biocompatibility and tunable mechanical properties to investigate the role of graft compliance in the development of intimal hyperplasia and patency. Two groups of PVA small diameter grafts with low compliance and high compliance were fabricated by dip casting method and implanted in a rabbit carotid artery end-to-side anastomosis model for 4 weeks. We demonstrated that the grafts with compliance that more closely matched with rabbit carotid artery had lower anastomotic intimal hyperplasia formation and higher graft patency compared to low compliance grafts. Overall, this study suggested that reducing the compliance mismatch between the native artery and vascular grafts is beneficial for reducing intimal hyperplasia formation.
Topics: Animals; Rabbits; Hyperplasia; Blood Vessel Prosthesis; Compliance; Carotid Arteries; Thrombosis
PubMed: 36943136
DOI: 10.1039/d3bm00167a -
Neurogastroenterology and Motility Jul 2012Colonic mechanosensory afferents 'in parallel' to circular muscle activate prevertebral ganglion reflexes; 'in series', afferents convey visceral sensation to the... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Colonic mechanosensory afferents 'in parallel' to circular muscle activate prevertebral ganglion reflexes; 'in series', afferents convey visceral sensation to the central nervous system; and pain receptors are activated with muscle distension. Our aim was to analyze the relationships of gas and pain sensations during graded distensions, and the association of sensations with colonic compliance in conscious humans.
METHODS
The data were acquired in a prior study performed on 60 healthy volunteers (aged 18-75 years) under baseline conditions. Colonic compliance was measured in response to 4 mmHg stepwise balloon distensions to estimate pressure at half-maximum volume (Pr(50%)). Sensation ratings for gas and pain were averaged over distensions at 16, 24, 30 and 36 mmHg above baseline operating pressure. Associations between mean gas and pain ratings, and colonic compliance were assessed with Pearson correlations.
KEY RESULTS
Gas and pain sensations were significantly correlated at all levels of distension (all P < 0.001). Significant inverse correlations between Pr(50%) and sensations of gas and pain were observed, suggesting that lower compliance was associated with lower sensations. Up to 25% of the variance in sensation may be attributed to colonic compliance.
CONCLUSIONS & INFERENCES
These data are consistent with the hypothesis that, if circumferential colonic receptors are stimulated by distension to mediate gas and pain in humans, they are, at least partly, arranged 'in parallel' to the muscle layer.
Topics: Adolescent; Adult; Aged; Colon; Compliance; Dilatation, Pathologic; Female; Gases; Humans; Male; Manometry; Middle Aged; Muscle, Smooth; Nociceptors; Visceral Pain; Young Adult
PubMed: 22393902
DOI: 10.1111/j.1365-2982.2012.01901.x -
Interactive Cardiovascular and Thoracic... Jul 2016To gain differential knowledge about the physiological compliance and wall strength of the different regions of the aorta, including the ascending aorta, arch and...
OBJECTIVES
To gain differential knowledge about the physiological compliance and wall strength of the different regions of the aorta, including the ascending aorta, arch and descending aorta in both the circumferential and longitudinal directions, and to generate a hypothesis on the pathophysiological mechanisms that lead to Type A aortic dissection.
METHODS
Fresh tissue specimens from 22 ex vivo porcine aortas were analysed on a tensile tester. Regional and directional compliance, failure stress and failure strain were recorded.
RESULTS
Aortic compliance appeared as a linear function of the natural logarithm (ln) of wall stress. Compliance significantly decreased along the length of the aorta. In the ascending aorta, longitudinal compliance significantly (P = 0.003) exceeded circumferential compliance, and the outer curvature was more compliant than the inner curvature (P = 0.03). In the descending aorta, this relationship is reversed: the circumferential compliance exceeded the longitudinal compliance, and the outer aspect was more compliant (P = 0.003). The median circumferential failure stress of all aortic segments was in the range of 2000-2750 kPa, whereas the longitudinal failure stress in the ascending aorta and the arch had values of 750-1000 kPa, which were significantly lower (P < 0.05). Surprisingly, the longitudinal failure stress of the inner aspect of the descending aorta was extraordinarily high (2000 kPa). Failure strain, similar to compliance, was highest in the ascending aorta and decreased along the aorta.
CONCLUSION
The aorta appears to be a complex organ with distinct regional and directional differences in compliance and wall strength that is designed to effectively absorb the kinetic energy of cardiac systole and to cushion the momentum of systolic impact. Under normotensive conditions and a preconditioned physiological morphology, the aortic wall works in the steep part of the logarithmic strain-stress function; under hypertensive conditions and pathological morphology, the wall reacts in an non-compliant manner. The high longitudinal compliance and low failure stress of the ascending aorta and subsequent pathological changes may be the main determinants of the recurrent patho-anatomy of Type A aortic dissection.
Topics: Aortic Dissection; Animals; Aorta; Aortic Aneurysm, Thoracic; Blood Pressure; Compliance; Disease Models, Animal; Stress, Mechanical; Swine; Tensile Strength; Tissue Culture Techniques
PubMed: 26993474
DOI: 10.1093/icvts/ivw053 -
Science (New York, N.Y.) Aug 2021Arboreal animals often leap through complex canopies to travel and avoid predators. Their success at making split-second, potentially life-threatening decisions of...
Arboreal animals often leap through complex canopies to travel and avoid predators. Their success at making split-second, potentially life-threatening decisions of biomechanical capability depends on their skillful use of acrobatic maneuvers and learning from past efforts. Here, we found that free-ranging fox squirrels () leaping across unfamiliar, simulated branches decided where to launch by balancing a trade-off between gap distance and branch-bending compliance. Squirrels quickly learned to modify impulse generation upon repeated leaps from unfamiliar, compliant beams. A repertoire of agile landing maneuvers enabled targeted leaping without falling. Unanticipated adaptive landing and leaping "parkour" behavior revealed an innovative solution for particularly challenging leaps. Squirrels deciding and learning how to launch and land demonstrates the synergistic roles of biomechanics and cognition in robust gap-crossing strategies.
Topics: Animals; Biomechanical Phenomena; Compliance; Locomotion; Sciuridae; Trees
PubMed: 34353955
DOI: 10.1126/science.abe5753