Vascular function tests to assess risk for cardiovascular diseases

Ultrasound examination, computed tomography, and/or magnetic resonance imaging can be employed to easily assess the severity of atherosclerotic vascular damage morphologically. On the contrary, the pulse wave velocity (PWV), pulse wave analysis (augmentation index: AI), and/or flow-mediated vasodilatation of the brachial artery(FMD) can reveal atherosclerotic functional vascular abnormalities. Recent meta analyses demonstrated that PWV and/or AI are markers which can be used to predict future cardiovascular events independent of conventional risk factors for cardiovascular disease. In this review, we discuss the applicability and limitations of vascular function tests.     

Intima-media thickness and pulse wave velocity in hypertensive adolescents

Increased intima-media thickness (IMT) and pulse wave velocity (PWV) are noninvasive markers of early arterial wall alteration and are more widely used in adult clinical research. We investigated whether IMT and PWV are useful predictors of cardiovascular risk in hypertensive adolescents. Fifteen hypertensive adolescents (13-18 yr old, systolic BP > or = 140 mmHg, diastolic BP > or = 90 mmHg) and seventeen normotensive subjects were included. Height, weight, obesity index, body mass index (BMI), and fat distribution were obtained from each group. Serum lipid, insulin, vitamine B12, folate, renin, aldosterone, angiotensin-converting enzyme (ACE), and homocysteine levels were compared. The carotid IMT and PWV were measured. Arterial wall compliance and distensibility were calculated with the equation. High systolic blood pressure significantly correlated with height, weight, BMI, obesity index, arm circumference, fat mass, and fat distribution. Hypertensive adolescents had significantly greater cIMT (carotid intima-media thickness) and lower elastic properties such as cross-sectional compliance and distensibility of the carotid artery. The carotid IMT significantly correlated with brachial-ankle PWV. In conclusion, the measurement of carotid IMT and brachial-ankle PWV might be useful to predict the development of atherosclerosis in hypertensive adolescents.     

Coronary hemodynamics and atherosclerotic wall stiffness: a vicious cycle

Local hemodynamic environment, including low shear stress and increased tensile stress, determines the localization, growth and progression of coronary atherosclerosis. As atherosclerotic lesions evolve, the diseased coronary arteries undergo local quantitative and qualitative changes in their wall, and progressively become stiff. Arterial stiffening amplifies the atherogenic local hemodynamic environment, initiating a self-perpetuating vicious cycle, which drives the progression of atherosclerosis and the formation of atherosclerotic plaque. In vivo evidence indicates that endothelial dysfunction is associated with arterial stiffness, an association that creates a challenging perspective of utilizing stiffness as an early marker of endothelial dysfunction and future atherosclerosis. Coronary stiffening is also associated with vascular remodeling, which is a major determinant of the natural history of atherosclerotic plaques. Thus, arterial stiffness may constitute a useful marker for the identification of the remodeling pattern, in particular expansive remodeling, which is closely associated with high-risk plaques. The early identification of endothelial dysfunction, or a high-risk plaque may enable the early adoption of preventive measures to improve endothelial function, or justify pre-emptive local interventions in high-risk regions to prevent future acute coronary syndromes. Further experimental and perspective clinical studies are needed for the investigation of these perspectives, whereas the development of new modalities for non-invasive and reliable assessment of coronary stiffness is anticipated to serve these studies.     

Cardiovascular risks related to increased diastolic, systolic and pulse pressure. An epidemiologist's point of view.

Since the introduction of the sphygmomanometer at the beginning to the 20th century, the significance of diastolic (DBP), Systolic (DBP) and pulse pressure (PP) as hypertensive cardiovascular risk factors has been controversial. These historical controversies are reviewed. Initially, DBP was thought to be the best measure of risk, but more recently both SBP and DBP, which ever is higher, are used in classifying hypertensive cardiovascular risk. There are problems with the present guidelines, in that SBP and DBP represent only two inflection points on the propagated pulse wave that is measured by cuff readings at the peripheral brachial artery. The heart is exposed to the central aortic pressure not to the brachial artery pressure. Moreover, both peripheral vascular resistance and large artery stiffness contribute to hypertensive cardiovascular risk. In middle-aged and elderly, elevated SBP is a better surrogate measurement of resistance than DBP, but SBP underestimates large artery stiffness. PP, the difference between peak SBP and end DBP, is the single best blood pressure surrogate for large artery stiffness. Epidemiological studies over the past decade point to SBP and DBP as the best cardiovascular risk markers for young subjects, whereas PP takes over as the more powerful risk marker for middle-aged and elderly subjects. These findings support the concept that cardiovascular events are more related to the pulsatile stress of large artery stiffness during systole than the steady-state stress of small vessel resistance during diastole. Therefore, at similar elevations of SBP, subjects with isolated systolic hypertension are at greater risk for cardiovascular events than those with combined systolic/diastolic hypertension.     

Systemic lupus erythematosus and cardiovascular disease: prediction and potential for therapeutic intervention

Patients with systemic lupus erythematosus have a significantly increased risk of cardiovascular events due to atherosclerosis. Traditional cardiac risk factors cannot fully explain this increased risk. Recent evidence strongly suggests that atherosclerotic plaque is largely driven by inflammation and an active immunological response, in contrast to the long-held belief that plaque is a passive accumulation of lipids in the arterial wall. Current approaches to the prevention of atherosclerosis in systemic lupus erythematosus involve targeting modifiable cardiac risk factors. Future preventive strategies may include therapies that counteract the immunologic responses that lead to plaque formation.     

Systemic lupus erythematosus and cardiovascular disease: prediction and potential for therapeutic intervention

Patients with systemic lupus erythematosus have a significantly increased risk of cardiovascular events due to atherosclerosis. Traditional cardiac risk factors cannot fully explain this increased risk. Recent evidence strongly suggests that atherosclerotic plaque is largely driven by inflammation and an active immunological response, in contrast to the long-held belief that plaque is a passive accumulation of lipids in the arterial wall. Current approaches to the prevention of atherosclerosis in systemic lupus erythematosus involve targeting modifiable cardiac risk factors. Future preventive strategies may include therapies that counteract the immunologic responses that lead to plaque formation.     

Inflammatory markers and cytokines in cardiovascular disease

Inflammatory processes play a pivotal role in the pathogenesis of atherosclerosis and mediate the stages of atheroma development from initial leukocyte recruitment to eventual rupture of the unstable atherosclerotic plaque. Recent investigations demonstrated that several inflammatory markers are considered as new predictable risk factors for atherosclerosis and cardiac events. Among these markers, C-reactive protein (CRP) has been most widely studied. CRP is produced in the liver in response to interleukin-6 (IL-6), it is an acute phase reactant and used as a general inflammatory marker. High-sensitivity-CRP (hs-CRP) which could detect a small amount of CRP was recently developed, and numerous large-scale, prospective studies have found that elevated baseline levels of hs-CRP are independent predictor of cardiovascular events. Inflammatory cytokines such as IL-6 and tumor necrosis factor-alpha (TNF-alpha) have also been evaluated as potential tools for prediction of the cardiovascular events. In this review, we focused on the recent reports and potential use of the inflammatory markers and cytokines as a predictable tool for the cardiovascular events.     

基于压力波的人体脉搏波传播速度无创检测研究

脉搏波传播速度的变化往往是血管弹性程度发生变化的最早体征,因此脉搏波速度的检测对动脉硬化等疾病的诊断有较高的参考价值,其检测精度主要取决于波速参考点的提取算法。在分析实际采集的脉搏压力波信号特征的基础上,对波峰、波足等特征点进行了识别,并提出了一种根据脉搏波前沿内斜率最大值点的个数和位置确定惟一波速参考点的新算法。临床实验证明,新方法能够有效地提取脉搏波速度,有助于动脉血管弹性程度的辅助诊断。     

Arterial stiffness,the hidden face of cardiovascular risk in autoimmune and chronic inflammatory rheumatic diseases

Background and objectiveCardiovascular diseases (CVD) are the leading causes of death in chronic inflammatory rheumatic diseases and are not solely explained by the increased prevalence of cardiovascular (CV) risk factors in this population. Arterial stiffness, assessed primarily by pulse wave velocity (PWV) and more indirectly by augmentation index (AIx), is a surrogate marker of CVD that should be considered. The objective of this review was to investigate the relationship between arterial stiffness and chronic inflammatory and/or autoimmune diseases.MethodsWe performed a systemic literature review of articles published in Medline from January 2012 to April 2020 restricted to English languages and to human adults. We selected relevant articles about the relationship between arterial stiffness and rheumatoid arthritis, systemic lupus erythematosus, psoriasis, Sjogren's syndrome and ankylosing spondylitis. For each selected article, data on PWV and AIx were extracted and factors that may have an impact on arterial stiffness were identified.ResultsA total of 214 references were identified through database searching and 82 of them were retained for analysis. Arterial stiffness is increased in chronic inflammatory and autoimmune diseases. Traditional CV risk factors such as hypertension and dyslipidemia accentuate this relationship. Current data are insufficient to determine whether disease activity significantly influences arterial stiffness, whereas disease duration seems rather critical. TNF-alpha inhibitors and cardiorespiratory fitness tend to decrease arterial stiffness. Finally, increased arterial stiffness leads to diastolic dysfunction, which is the main mechanism of heart failure in chronic inflammatory rheumatic diseases.ConclusionCV risk assessment in chronic inflammatory and autoimmune diseases should also rely on PWV and AIx.     

Osteoporosis,osteopenia, and atherosclerotic vascular disease

Older women with low bone mineral density (BMD) have a higher prevalence of atherosclerotic vascular disease (coronary artery disease, ischemic stroke, or peripheral arterial disease) than older women with normal BMD. Three coronary angiographic studies have shown that low BMD is associated with obstructive coronary artery disease. Low BMD has been shown to be associated with stress test-induced myocardial ischemia, reduced exercise capacity, and with aortic valve calcification. Women with osteoporosis have an increased risk for cardiovascular events. Treatment of osteoporosis or osteopenia should include therapeutic measures to prevent cardiovascular events.     

Numerical Validation of a New Method to Assess Aortic Pulse Wave Velocity from a Single Recording of a Brachial Artery Waveform with an Occluding Cuff

Recently a new method has been proposed as a tool to measure arterial pulse wave velocity (PWV), a measure of the stiffness of the large arteries and an emerging parameter used as indicator of clinical cardiovascular risk. The method is based on measurement of brachial blood pressure during supra-systolic pressure inflation of a simple brachial cuff [the device is known as the Arteriograph (Tensiomed, Budapest, Hungary)]. This occlusion yields pronounced first and secondary peaks in the pressure waveform, the latter ascribed to a reflection from the aortic bifurcation, and PWV is calculated as the ratio of twice the jugulum-symphysis distance and the time difference between the two peaks. To test the validity of this working principle, we used a numerical model of the arterial tree to simulate pressures and flows in the normal configuration, and in a configuration with an occluded brachial artery. A pronounced secondary peak was indeed found in the brachial pressure signal of the occluded model, but its timing was only related to brachial stiffness and not to aortic stiffness. We also compared PWV’s calculated with three different methods: PWV_ATG (~Arteriograph principle), PWV_car–fem (~carotid–femoral PWV, the current clinical gold standard method), and PWV_theor (~Bramwell–Hill equation). Both PWV_ATG (R ² = 0.94) and PWV_car–fem (R ² = 0.95) correlated well with PWV_theor, but their numerical values were lower (by 2.17 ± 0.42 and 1.08 ± 0.70 m/s for PWV_ATG and PWV_car–fem, respectively). In conclusion, our simulations question the working principle of the Arteriograph. Our data indicate that the method picks up wave reflection phenomena confined to the brachial artery, and derived values of PWV rather reflect the stiffness of the brachial arteries.     

Prevalence and severity of atherosclerosis in different arterial territories and its relation with obesity

BackgroundThere is uneven association between obesity, traditional risk factors, and cardiovascular events. We aimed to analyze the relation between cardiovascular risk factors, including obesity, with the severity of atherosclerosis in different arterial territories.MethodsArteries from five territories (circle of Willis, carotids, coronaries, aorta, and renal) were taken from 185 persons, newborn to 90 years undergoing autopsy in the Forensic Medical Service in Mexico City, to determine atherosclerotic lesions by histopathological study. Lesions were classified according to the American Heart Association grading system as early (types I–III) and advanced (types IV–VI). The degree of atherosclerosis was correlated with arterial territories and risk factors.ResultsFrequencies of advanced lesions according to arterial territories were as follows: circle of Willis, 28%; right carotid, 36%; left carotid, 25%; right coronary, 71%; left coronary, 85%; right renal, 26%; left renal, 29%; and aorta, 52%; P=.0001, for all analyses. There was a higher risk for advanced lesions with increasing body mass index (BMI) (P=.004). However, after adjusting for age, gender, smoking status, hypertension, and diabetes mellitus, BMI was not independently associated with advanced lesions.ConclusionsCoronary arteries are significantly more affected than other arterial territories regardless of risk factors, showing the effect of local and systemic factors in the severity of atherosclerosis. We did not find an independent association between advanced atherosclerotic lesions and obesity.     

Rigidity of large arteries and cardiovascular risk. epidemiological aspects and genetic determinants]

Most of the morbid events due to hypertension and other risk factors are related to alterations of the large arteries of the brain, the heart or the kidney. Historically large arteries have been considered as passive conduits of blood, and physicians, surgeons and pathologists were mainly interested on their anatomical lesions such as rupture, stenosis, aneurysm, or thrombosis. However we know that large arteries are not passive conduit tubes but are characterized by elastic properties and are able to synthesize many vasoactive substances. These properties make the arterial wall a major modulator of the blood pressure and more generally of the cardiovascular regulation. Aging, environmental and genetic factors are responsible for structural and functional changes of the arterial wall media (hypertrophy, extracellular matrix accumulation, calcium deposits) and of the vascular endothelium (decrease in the release of vasodilators and increased synthesis of vasoconstrictors), all that leading to a diminution of elasticity and increased stiffness. The alteration of large arteries elasticity has deleterious effects on the heart upstream being responsible for an inadequate increase in systolic pressure and a relative decrease in aortic diastolic pressure at any given value of mean arterial pressure. The elevation in systolic pressure causes a disproportionate increase in end-systolic stress, which is the principal hemodynamic factor which promotes the development of cardiac hypertrophy, increased ventricular oxygen consumption, and left ventricular hypertrophy and can compromise capacity for coronary perfusion. Clinical and epidemiological studies have raised the possibility that subjects with stiffer arteries have wide pulse pressure, and that stiffening of large arteries is associated with excess morbidity and mortality independently of mean blood pressure. In addition to its etiologic role in cardiovascular disease, increased arterial stiffness may serve as an early marker for the diagnosis of asymptomatic atherosclerotic lesions, or for the evaluation of the severity of these lesions. In this review we report data from clinical, epidemiological and genetic studies, suggesting that arterial stiffness may be considered as a significant marker and/or an independent cardiovascular risk factor. This new concept should lead physicians to evaluate arterial stiffness for the prognosis and treatment of cardiovascular patients.     

基于脉搏波的新型血压与血管硬度测量仪的研制

目的：根据脉搏波理论研制出一种新型血压与血管硬度测量仪。方法：利用示波法原理在波形特征法和幅度系数法的基础上提出一种系数差分比值法来间接测量血压的新方法，通过采集肱动脉和桡动脉两处波形，获得了脉搏波传播速度（PWv）、动脉顺应性（C1、C2）和动脉硬化指数（ASI）三个反映受试者动脉弹性的参数指标。结果：通过大量病例分析和临床测试证实了算法的有效性和可靠性，而且此算法已经应用LabVIEW开发成软件并在医院进行临床应用。结论：血压与血管硬度检测仪能判断心血管病患者与正常人的差异性，对我国心血管病方面流行病学的调查、疾病预防、疾病早期发现都具有很大的意义。     

Endogenous pro-resolving and anti-inflammatory lipid mediators: the new hope of atherosclerotic diseases

Atherosclerosis is a complex disease process in which genetic, lipid, cellular, and immunological factors combine to determine the location, severity, and timing of lesion development and clinical events. It has been demonstrated, however, that inflammation governed atherosclerosis during the course of development of atherosclerosis. It has also been demonstrated to be effective to decrease the cardiovascular events and improve the prognosis of atherosclerotic diseases by regulating inflammatory reaction (e.g., statins). However, endogenous mechanisms of limiting inflammation in atherosclerosis are still unclear. Recent studies showed that lipoxidase/leukotrienes (LOX/LTs) pathway played important role in the ignition and development of atherosclerosis, whereas resolvins (E-series resolvins and D-series resolvins) and protectins [protectin D1 (PD1) and neuroprotectin D1 (NPD1)], endogenous lipid-derived mediators, inhibited inflammation through pro-resolution and counter-modulating immune inflammation reaction in atherosclerosis. Hence, we hypothesize that increased endogenous lipid mediators mentioned above play a vital role in anti-atherosclerosis and plaque stabilization through pro-resolution and anti-inflammation by LOX/LTs pathway. In addition, we predict that the endogenous lipid mediators may be a new target for treatment of atherosclerotic diseases.     

Morphometric Studies of Human Coronary Artery Trees in Healthy and Disease

Objective According to the report from American Heart Association(AHA),cardiovascular diseases(CVDs)are the leading causes of death globally,and coronary artery disease(CAD),known as coronary atherosclerotic plaques,accounts for over 30%of cardiovascular diseases.Therefore,it is of great clinical significance to study the relationship between coronary bifurcations morphometrical feature change and coronary artery disease.Although coronary atherosclerosis has been extensively investigated,there is a lack of in-deep study on the differences in morphometric features between optimal and realistic geometry of coronary arterial trees.The purpose of the present paper is to determine the morphological changes in patients with CAD lesion compared with non-coronary artery disease(non-CAD)subjects.Methods Due to the difficulty of studying the coronary bifurcations in vivo,image-based in vitro anatomical 3D models have been widely used as a noninvasive method for morphometric measurement and clinical diagnosis of the coronary bifurcations.With the development of coronary computed tomography angiography(CTA)hardware and software technologies,the CTA imaging technique has been shown a promising application in the characterization,visualization,and identification of coronary artery disease in recent decades.The CTA images used to reconstruct three-dimensional(3D)coronary arterial trees are from Asia populations(Southern Chinese populations),including five cadavers without CAD lesion and 102 patients with CAD lesion.The best fit artery diameter was calculated as twice the average radius between the points in the centerlines and the points on the coronary arterial inner wall.The bifurcation angles between larger daughter artery and smaller daughter artery were determined by the intersection angle of their centerlines.Murray's law was introduced to assess the deviation of the realistic vascular networks from its optimal state.Results Based on the morphometric analysis of coronary artery bifurcations in non-CAD subjects and patients with CAD lesion subjects,the most important finding is that morphological feature parameters of non-CAD subjects are closer to the optimal values than those of patients with CAD lesion.Moreover,by comparing the morphometric data between the left and right coronary arteries,the right coronary artery exhibits a structure closer to the optimal one in morphological feature than the left coronary artery.In addition,coronary arterial trees with CAD lesion have higher asymmetry and larger area expansion ratio(AER)than those of the coronary arterial trees without CAD lesion.Conclusions We morphologically found that the coronary arterial trees with CAD lesion and left are more likely to deviate from the optimal structure predicted by Murray's law than those without CAD lesion and right.The degree to which coronary arterial system deviating from their optimal state may directly affect the incidence of coronary artery disease.This computer morpho-logical analysis strategy is illustrated to be effective in the distinguishing of the geometric differences between the healthy and diseased coronary arteries,and the analysis method may have a large potential in cardiovascular disease earlier diagnosis.     

Coronary artery calcification, common carotid artery intima-media thickness and aortic pulse wave velocity in patients on peritoneal dialysis

An increasing body of evidence suggests that atherosclerosis in patients with uremia differs from that found in general population in terms of advancement and localization of vascular lesions. It has also been suggested that different non-invasive techniques of vascular system evaluation are designed to show different types of lesions (i.e. vascular calcification, stiffness or 'classical' atherosclerosis). The aim of the study was to search for possible associations between results obtained with three different non-invasive methods of vascular system assessment in three different vascular sites in patients treated with peritoneal dialysis (PD). 61 patients (28 F, 33 M), mean age of 50.4+/-13.6 years, on maintenance PD for a median period of 10 months (range 1-96 months) were included. Coronary artery disease (CAD) was present in 21 subjects. In all subjects coronary artery calcification score (CaSc) using multi-row spiral computed tomography (MSCT), aortic pulse wave velocity (AoPWV) and ultrasound-based common carotid artery intima-media thickness (CCA-IMT) were performed as methods for assessing coronary calcium burden, arterial stiffness and atherosclerosis, respectively. Median value of CaSc equaled 11.5 Agatston units (range 0-5502.8 units). Median AoPWV was 10.4 m/s (range 7.56-18.1 m/s), and median CCA-IMT-0.6 mm (range 0.3-1.0 mm). In 16 patients (26.2%) at least one plaque in at least one common carotid artery was found on ultrasound. CaSc correlated with AoPWV (R=0.32, p<0.01) and with CCA-IMT (R=0.35, p<0.005), whereas no association was found between AoPWV and CCA-IMT. AoPWV, but not CaSc nor IMT correlated with blood pressure. The values of CCA-IMT and AoPWV increased together with consecutive Agatston categories (with p<0.001 for differences in AoPWV and p<0.05 for CCA-IMT). Patients with at least one plaque found in at least one CCA and patients with CAD were characterized with significantly higher values of CaSc, IMT and PWV, when compared to plaque-free and CAD- negative subjects, respectively. Association between CaSc and both IMT and PWV may suggest that the mechanism of three assessed vascular pathologies may be based, to some extent, on the process of pathologic calcium-phosphate deposition. Lack of correlation found between PWV and IMT may suggest that aortic stiffness and carotid atherosclerosis may partially differ in their pathologic background and/or are dissociated in time.     

Elevated arterial stiffness in postmenopausal women with osteoporosis

OBJECTIVES: Osteoporosis and increased pulse wave velocity (PWV) are cardiovascular risk factors. We investigated the relationship between PWV and bone mass in the lumbar spine in postmenopausal women. METHODS: We studied the PWV in 95 women; 38 postmenopausal women with normal spinal bone mineral density (BMD), 32 osteopenic postmenopausal women, and 25 osteoporotic postmenopausal women. The brachial-ankle PWV (baPWV) was measured using an automated device. The BMD of the lumbar spine (L2-L4) was measured using dual-energy X-ray absorptiometry. RESULTS: After adjusting for age and years since menopause, women with osteoporosis had a significantly higher baPWV than those with normal BMD (1500 +/- 220 cm/s versus 1340 +/- 215 cm/s; P < 0.05), but no significant differences in baPWV were seen between the osteoporotic and osteopenic groups or between the osteopenic and normal BMD groups. In univariate regression analysis, the baPWV was significantly negatively correlated with BMD (r = -0.450, P < 0.01), and significantly positively correlated with age (r = 0.601, P < 0.01), years since menopause (r = 0.577, P < 0.01), systolic blood pressure (r = 0.295, P < 0.01), and diastolic blood pressure (r = 0.264, P < 0.05), but was not with other variables. In multivariate regression analysis, the baPWV was significantly correlated with BMD (P < 0.05), but not with other variables. CONCLUSIONS: Postmenopausal women with osteoporosis may have elevated arterial stiffness, suggesting that osteoporotic postmenopausal women may have a higher risk of cardiovascular disease.     

Pathophysiology and diagnosis for arteriosclerosis obliterans

Patients with arteriosclerosis obliterans, or peripheral arterial disease have been conventionally diagnosed and treated from only the viewpoint of peripheral arterial circulation. These concepts may have improved the quality of life for patients, but could not contribute the prognosis of life, because peripheral arterial disease is associated with an increased risk of the coronary disease and cerebrovascular disease. Intermittent claudication, the most common symptom of peripheral arterial disease, results from flow-reducing lesions in the arteries of the lower extremity that cause exercise-induced muscle ischemia. In order to evaluate intermittent claudication, many kinds of noninvasive diagnostic studies, including ABPI (ankle brachial pressure index) and the measurement of claudication distance, et al have been proposed. We have used the recovery time of the ischemic reaction at foot sole, plethysmography, thermography, laser doppler flowmetry, or NIRS (near-infrared spectroscopy) after walking test, rather than ABPI. These examinations will be superior to ABPI to evaluate effects after ergotherapy or pharmacotherapy for patients with intermittent claudication. Carotid artery sclerosis may be a good marker of systemic atherosclerosis. By our assessment of risk factors, the progression of atherosclerotic change in carotid artery was strongly correlated with two risk factors, such as smoking and systolic blood pressure. In the cholesterol analysis, Lp (a) was only high risk factor for atherosclerotic change of carotid artery. Recent technical advances, adequate evaluation of systemic atherosclerosis, and reduction of risk factors should improve the prognosis of patients with peripheral arterial disease.     

An Integrative Model of the Cardiovascular System Coupling Heart Cellular Mechanics with Arterial Network Hemodynamics

The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements.