共查询到20条相似文献,搜索用时 14 毫秒
1.
The aim of this study was to investigate the contribution of direct right-to-left ventricular interaction to left ventricular filling and stroke volume in 46 patients with pulmonary arterial hypertension (PAH) and 18 control subjects. Stroke volume, right and left ventricular volumes, left ventricular filling rate, and interventricular septum curvature were measured by magnetic resonance imaging and left atrial filling by transesophageal echocardiography. Stroke volume, left ventricular end-diastolic volume, and left ventricular peak filling rate were decreased in PAH patients compared with control subjects: 28 +/- 13 vs. 41 +/- 10 ml/m(2) (P < 0.001), 46 +/- 14 vs. 61 +/- 14 ml/m(2) (P < 0.001), and 216 +/- 90 vs. 541 +/- 248 ml/s (P < 0.001), respectively. Among PAH patients, stroke volume did not correlate to right ventricular end-diastolic volume or mean pulmonary arterial pressure but did correlate to left ventricular end-diastolic volume (r = 0.62, P < 0.001). Leftward interventricular septum curvature was correlated to left ventricular filling rate (r = 0.64, P < 0.001) and left ventricular end-diastolic volume (r = 0.65, P < 0.001). In contrast, left atrial filling was normal and not correlated to left ventricular end-diastolic volume. In PAH patients, ventricular interaction mediated by the interventricular septum impairs left ventricular filling, contributing to decreased stroke volume. 相似文献
2.
目的:比较原发性高血压患者和健康对照个体血浆脑钠肽水平的差别,研究BNP同左室重量指数的关系,从而探讨BNP与高血压性心室重构的相关性.方法:收集我院2007年-2010年住院及门诊原发性高血压患者86例,以及健康体检者31例,均行血浆BNP,血清hs-CRP,总胆固醇(TC),甘油三酯(TG),低密度脂蛋白胆固醇(LDL-C),高密度脂蛋白胆固醇(HDL-C),尿素氮(BUN),肌酐(CR),尿酸(UA)测定,同时行彩色多普勒超声心动图检查,记录室间隔厚度(IVST),左室后壁厚度(LVPWT),左室舒张末期内径(LVEDd),左室收缩末期内径(LVEDs),EF值,根据各项超声指标,计算出左室重量及左室重量指数LVMI=LVM/BSA.LVMI=LVM/BSA.所有研究对象分为EH组及健康对照组,86例EH患者按照血压水平的不同分为EH1,EH2,EH3等3组,按照是否合并有LVMI水平增高分为单纯EH组和EH合并LVH组.结果:①EH组较健康对照组BNP水平增高,差别有统计学意义(P=0.019,P<0.05)o②EH1,EH2,EH3组两两比较,EH3组较EH1组,EH2组BNP水平增高(P=0.026,0.029,P<0.05),EH1,EH2组之间差别无统计学意义(P>0.05).③EH合并LVH组较单纯EH组BNP水平增高(P=0.036,P<0.05).④随着血浆BNP水平的增高,LVMI增大,二者之间呈正相关关系(r=0.591,P<0.05);BNP与UA,LVEDd呈正相关关系(r=0.355,0.423,P均<0.05).结论:高血压患者存在BNP水平的增高;BNP可反映高血压心室重构的程度. 相似文献
3.
A computationally efficient method is described for simulating the dynamics of the left ventricle (LV) in three dimensions. LV motion is represented as a combination of a limited number of deformation modes, chosen to represent observed cardiac motions while conserving volume in the LV wall. The contribution of each mode to wall motion is determined by a corresponding time-dependent deformation variable. The principle of virtual work is applied to these deformation variables, yielding a system of ordinary differential equations for LV dynamics, including effects of muscle fiber orientations, active and passive stresses, and surface tractions. Passive stress is governed by a transversely isotropic elastic model. Active stress acts in the fiber direction and incorporates length–tension and force–velocity properties of cardiac muscle. Preload and afterload are represented by lumped vascular models. The variational equations and their numerical solutions are verified by comparison to analytic solutions of the strong form equations. Deformation modes are constructed using Fourier series with an arbitrary number of terms. Greater numbers of deformation modes increase deformable model resolution but at increased computational cost. Simulations of normal LV motion throughout the cardiac cycle are presented using models with 8, 23, or 46 deformation modes. Aggregate quantities that describe LV function vary little as the number of deformation modes is increased. Spatial distributions of stress and strain change as more deformation modes are included, but overall patterns are conserved. This approach yields three-dimensional simulations of the cardiac cycle on a clinically relevant time-scale. 相似文献
4.
We investigated the impact of obesity on the abnormalities of systolic and diastolic regional left ventricular (LV) function in patients with or without hypertension or hypertrophy, and without heart failure. We studied 120 individuals divided into 6 groups of 20 patients (42 ± 6 years, 60 females) using standard and pulsed-wave tissue Doppler imaging (TDI) echocardiography, and heterogeneity index (HI): nonobese (I: no hypertension, no hypertrophy, control group; II: hypertension, no hypertrophy; III: hypertension and hypertrophy) and obese (IV: no hypertension, no hypertrophy; V: hypertension, no hypertrophy; VI: hypertension and hypertrophy). The criterion for obesity was BMI ≥30 kg/m2, for hypertension was blood pressure ≥ 140/90 mm Hg, for hypertrophy in nonobese was LV mass/body surface area (BSA) >134 g/m(2) (men) and >110 mg/m2 (women), and in obese was LV mass/height(2.7) >50 (men) and >40 (women). Obese groups had normal LV ejection fraction compared with nonobese groups, but decreased longitudinal and radial systolic myocardial peak velocities (S'), and early diastolic myocardial peak velocity (E'). Also, a great variability of E' and late diastolic myocardial peak velocity (A') from the longitudinal basal region was observed in obese groups (E'basal nonobese: 11 ± 7 vs. obese 19 ± 11, P < 0.001, A'basal nonobese: 7 ± 4 vs. obese 11 ± 7, P < 0.001). Our findings were more evident when comparing groups IV with V and VI, with the latter having concentric hypertrophy and obvious segmental systolic and diastolic dysfunctions. Subclinical myocardial alterations and increased variability of the velocities were observed in obese groups, especially with hypertension and hypertrophy, reflecting impaired regional LV relaxation, segmental atrial, and systolic dysfunctions. 相似文献
5.
目的:探讨超声对高血压心脏病患者左心室整体功能评价的临床价值.方法:69例高血压心脏病患者分为3组:A组26例左室壁厚度正常,B组23例仅室间隔增厚,C组20例室间隔与左室后壁均增厚,同时选择正常健康者D组48人为对照.常规行超声心动图检查,测量并计算出二尖瓣口血流频谱舒张早期和舒张晚期血流峰值之比(E/A)、左室射血分数(LVEF)及Tei指数等评价参数.结果:高血压心脏病A、B组LVEF值均在正常范围,C组LVEF值有所下降,但与对照组比较差异均无统计学意义(P>0.05),但E/A值均较对照组减小(P<0.05);高血压心脏病A、B和C组Tei指数分别为(0.49±0.15)、(0.56±0.10)和(0.56±0.10),高于正常对照组的(0.32±0.08)(P<0.05).结论:在LVEF正常情况下Tei指数能更早地全面反映高血压心脏病患者左心功能下降情况,并且不受心率、心室几何形态,心室收缩和舒张压等因素的影响,为临床早期干预治疗防止心衰发生提供了依据. 相似文献
7.
Chronic ouabain treatment produces hypertension acting on the central nervous system and at vascular levels. However, cardiac effects in this model of hypertension are still poorly understood. Hence, the effects of hypertension induced by chronic ouabain administration ( approximately 8 microg day(-1), s.c.) for 5 weeks on the cardiac function were studied in Wistar rats. Ouabain induces hypertension but not myocardial hypertrophy. Awake ouabain-treated rats present an increment of the left ventricular systolic pressure and of the maximum positive and negative dP/dt. Isolated papillary muscles from ouabain-treated rats present an increment in isometric force, and this effect was present even when inotropic interventions (external Ca(2+) increment and increased heart rate) were performed. However, the sarcoplasmic reticulum activity and the SERCA-2 protein expression did not change. On the other hand, the activity of myosin ATPase increased without changes in myosin heavy chain protein expression. In addition, the expression of alpha(1) and alpha(2) isoforms of Na(+), K(+)-ATPase also increased in the left ventricle from ouabain-hypertensive rats. The present results showed positive inotropic and lusitropic effects in hearts from awake ouabain-treated rats, which are associated with an increment of the isometric force development and of the activity of myosin ATPase and expression of catalytic subunits of the Na(+), K(+)-ATPase. 相似文献
8.
We investigated the performance of brain natriuretic peptides (BNP and NT-proBNP) in detecting various degrees of left ventricular systolic dysfunction. The NT-proBNP assay (Roche) and the BNP assay (Bayer Shionoria) were performed in 46 patients (mean age 50 years; range 20-79 years) with various types of heart disease (chronic heart failure due to coronary artery disease, cardiomyopathy, acquired valve disease, congenital heart diseases) and different impairment of left ventricular systolic dysfunction was assessed by echocardiography. Patients were divided into four groups according to the left ventricular ejection fraction (LVEF) correlated with clinical severity. Significant differences in medians of NT-proBNP and BNP values between all groups were determined (P= 0.0161 for NT-proBNP and P=0.0180 for BNP). For identifying patients with severe systolic dysfunction (LVEF<40%), receiver operating characteristic (ROC) analysis for both BNP and NT-proBNP was performed. The diagnostic performances expressed as areas under the curve were of 0.69 for NT-proBNP (cut off value 367 pg/ml) and 0.60 for BNP (cut off value 172 pg/ml). However, the BNP showed higher sensitivity (85 % vs. 63 %) and a higher positive predictive value (69 % vs 55 %) than the NT-proBNP. The negative predictive values of BNP and NT-proBNP were similar (70 % and 71 % respectively). Brain natriuretic peptides are promising markers for the diagnosis of severe left ventricular systolic dysfunction. 相似文献
9.
In order to evaluate the effect of PGI2 on left ventricular ejection fraction (LVEF) an intravenous infusion in 10 patients (3 males, 7 females; 36 to 63 years) with an impaired LVEF (34.7 +/- 14.8%) was performed. LVEF was determined by means of 99mTc-pertechnetate radionuclide ventriculography. An increase of LVEF to 36.2 +/- 13.5% during administration of PGI2 at a rate of 1 ng/kg/min for 15 min and to 43.8 +/- 15.8% during a rate of 5 ng/kg/min (p less than 0.01) for an additional 15 min was observed. Analyzing the data in more detail in 6 patients, an improvement in LVEF became obvious during the administration of 1 ng/kg/min (108, 109, 116, 118, 121, and 123% of pre-infusion value, respectively). In 5 out of these 6 patients a dose-increment to 5 ng/kg/min further increased LVEF (139, 179, 187, 148, and 128% of pre-infusion value, respectively). In contrast, in the other 4 patients no response of LVEF to PGI2 at a rate of 1 ng/kg/min could be observed. However, in 2 out of these 4 patients LVEF increased during the administration of 5 ng/kg/min (111 and 117% of pre-infusion value). Individual changes in hemodynamic parameters showed no correlation to the improvement seen in LVEF in response to PGI2. It is concluded that PGI2 may exert beneficial effects on LVEF, and might be used in certain clinical conditions, such as before heart transplantation, to achieve a temporary improvement in LVEF. 相似文献
10.
Left ventricular regional wall motion was evaluated in 11 patients with pulmonary hypertension and 18 control subjects. All 11 patients had secondary pulmonary hypertension and less than 20% measured diameter stenosis in any vessel. This study utilizes a video-intensity-based frame-by-frame computerized technique. All pulmonary hypertensive patients showed early diastolic asynchrony in the anterior or apical regions that lasted 100-200 ms. The size of the abnormal area varied from 2 to 20% of the ventricular silhouette. Four patients also showed systolic abnormalities. No abnormalities were detected in the control group. The cause of the asynchrony detected in pulmonary hypertension is probably due to interventricular interaction caused by pressure gradients across the septum. 相似文献
11.
At present, it is unknown why patients suffering from severe pulmonary hypertension (PH) benefit from atrial septostomy (AS). Suggested mechanisms include enhanced filling of the left ventricle, reduction of right ventricular preload, increased oxygen availability in the peripheral tissue, or a combination. A multiscale computational model of the cardiovascular system was used to assess the effects of AS in PH. Our model simulates beat-to-beat dynamics of the four cardiac chambers with valves and the systemic and pulmonary circulations, including an atrial septal defect (ASD). Oxygen saturation was computed for each model compartment. The acute effect of AS on systemic flow and oxygen delivery in PH was assessed by a series of simulations with combinations of different ASD diameters, pulmonary flows, and degrees of PH. In addition, blood pressures at rest and during exercise were compared between circulations with PH before and after AS. If PH did not result in a right atrial pressure exceeding the left one, AS caused a left-to-right shunt flow that resulted in decreased oxygenation and a further increase of right ventricular pump load. Only in the case of severe PH a right-to-left shunt flow occurred during exercise, which improved left ventricular preload reserve and maintained blood pressure but did not improve oxygenation. AS only improves symptoms of right heart failure in patients with severe PH if net right-to-left shunt flow occurs during exercise. This flow enhances left ventricular filling, allows blood pressure maintenance, but does not increase oxygen availability in the peripheral tissue. 相似文献
12.
Polymorphic markers were studied in mitochondrial DNA and the nuclear POLG1 gene, coding for mitochondrial DNA polymerase γ. Their frequencies were compared between healthy individuals and patients with arterial hypertension, as well as between patients with and without left ventricular hypertrophy. The healthy group was found not to be clearly dominated by the C allele of MspI polymorphism in POLG1. Mitochondrial haplogroup H was more frequent ( OR = 0.42; 95%CI 0.17–0.98; p = 0.043) in patients without left ventricular hypertrophy than in patients having this complication. Haplogroup T was more often detected in patients with left ventricular hypertrophy ( OR = 6.16; 95%CI 1.17–9.74; p = 0.018). This result suggests the implication of mitochondrial DNA in hereditary susceptibility to cardiovascular diseases. 相似文献
13.
The vertebrate embryonic ventricle transforms from a smooth-walled single tube to trabeculated right ventricular (RV) and left ventricular (LV) chambers during cardiovascular morphogenesis. We hypothesized that ventricular contraction patterns change from globally isotropic to chamber-specific anisotropic patterns during normal morphogenesis and that these deformation patterns are influenced by experimentally altered mechanical load produced by chronic left atrial ligation (LAL). We measured epicardial RV and LV wall strains during normal development and left heart hypoplasia produced by LAL in Hamburger-Hamilton stage 21, 24, 27, and 31 chick embryos. Normal RV contracted isotropically until stage 24 and then contracted preferentially in the circumferential direction. Normal LV contracted isotropically at stage 21, preferentially in the longitudinal direction at stages 24 and 27, and then in the circumferential direction at stage 31. LAL altered both RV and LV strain patterns, accelerated the onset of preferential RV circumferential strain patterns, and abolished preferential LV longitudinal strain (P < 0.05 vs. normal). Mature patterns of anisotropic RV and LV deformation develop coincidentally with morphogenesis, and changes in these deformation patterns reflect altered cardiovascular function and/or morphogenesis. 相似文献
14.
Background Power Doppler (PD) has improved diagnostic capabilities of vascular sonography, mainly because it is independent from the angle of insonation. We evaluated this technique in a prospective comparison with conventional imaging, consisting in Duplex and Color Doppler, for the evaluation of Renal Artery (RA) stenosis. Methods Sensitivity, specificity and predictive values of PD and conventional imaging were assessed in a blinded fashion on eighteen patients, 9 with angiographic evidence of unilateral RA stenosis (hypertensive patients) and 9 with angiographically normal arteries (control group). PD images were interpreted with an angiography-like criteria. Results In the control group both techniques allowed correct visualization of 16 out of the 18 normal arteries (93% specificity). Only in five hypertensive patients RA stenosis was correctly identified with conventional technique (56% sensitivity and 86% negative predictive value); PD was successful in all hypertensive patients (100% sensitivity and negative predictive value), since the operators could obtain in each case of RA stenosis a sharp color signal of the whole vessel with a clear "minus" at the point of narrowing of the lumen. All results were statistically significant (p < 0.01). Conclusions This study demonstrates that PD is superior to conventional imaging, in terms of sensitivity and specificity, for the diagnosis of RA stenosis, because it allows a clear visualization of the whole stenotic vascular lumen. Especially if it is used in concert with the other sonographic techniques, PD can enable a more accurate imaging of renovascular disease with results that seem comparable to selective angiography. 相似文献
16.
It has been reported that 30-40% of patients with aortic stenosis are hypertensive. In such patients, the left ventricle faces a double (i.e. valvular and vascular) pressure overload, which results in subsequent wall volume hypertrophy. From a clinical standpoint, it is difficult to separate the respective contributions of aortic stenosis and systemic hypertension to left ventricular burden and patient's symptoms and thus to predict whether valve replacement would be beneficial. The objective of this theoretical study was therefore to investigate the relative effects of valvular and vascular afterloads on left ventricular hypertrophy. We used a ventricular-valvular-vascular mathematical model in combination with the Arts' model describing the myofiber stress. Left ventricular wall volume was computed for different aortic blood pressure levels and different degrees of aortic stenosis severity. Our simulations show that the presence of concomitant systemic hypertension has a major influence on the development of left ventricular hypertrophy in patients with aortic stenosis. These results also suggest that mild-to-moderate aortic stenosis has a minor impact on left ventricular wall volume when compared with hypertension. On the other hand, when aortic stenosis is severe, wall volume increases exponentially with increasing aortic stenosis severity and the impact of aortic stenosis on left ventricular hypertrophy becomes highly significant. 相似文献
18.
Background2D strain imaging of the left atrium (LA) is a new echocardiographic method which allows us to determine contractile, conduit and reservoir functions separately. This method is particularly useful when changes are subtle and not easily determined by traditional parameters, as it is in arterial hypertension and atrial fibrillation (AF). The aims of our study were: to determine LA contractile, conduit and reservoir function by 2D strain imaging in patients with mild arterial hypertension and paroxysmal AF; to assess LA contractile, conduit and reservoir functions’ relation with LV diastolic dysfunction (DD) parameters.MethodsLA contractile, conduit and reservoir functions together with echocardiographic signs of LV DD were assessed in 63 patients with arterial hypertension and paroxysmal AF. Patients were grouped according to number of signs showing LV DD (annular e’ velocity: septal e’?<?7 cm/s, lateral e’?<?10 cm/s, average E/e’ ratio?>?14, LA volume index >?34 ml/m2, peak tricuspid regurgitation velocity?>?2.8 m/s) present. Number of patients with 0 signs – 17, 1 sign – 26, 2 signs – 19. Contractile, conduit and reservoir functions were compared between the groups.ResultsMean contractile, conduit and reservoir strains in all the patients were???14.14 (± 5.83) %, 15.98 (± 4.85) % and 31.03 (± 7.64) % respectively. Contractile strain did not differ between the groups. Conduit strain was higher in patients with 0 signs compared with other groups (p =?0.016 vs 1 sign of LV DD and p =?0.001 vs 2 signs of LV DD). Reservoir strain was higher in patients with 0 signs compared with other groups (p =?0.014 vs 1 sign of LV DD and p <?0.001 vs 2 signs of LV DD).ConclusionsThe patients with paroxysmal AF and primary arterial hypertension have decreased reservoir, conduit and pump LA functions even in the absence of echocardiographic signs of LV DD. With increasing number of parameters showing LV DD, LA conduit and reservoir functions decrease while contractile does not change. LA conduit and reservoir functions decrease earlier than the diagnosis of LV DD can be established according to the guidelines in patients with primary arterial hypertension and AF. 相似文献
20.
Previous studies of transmural left ventricular (LV) strains suggested that the myocardium overlying the papillary muscle displays decreased deformation relative to the anterior LV free wall or significant regional heterogeneity. These comparisons, however, were made using different hearts. We sought to extend these studies by examining three equatorial LV regions in the same heart during the same heartbeat. Therefore, deformation was analyzed from transmural beadsets placed in the equatorial LV myocardium overlying the anterolateral papillary muscle (PAP), as well as adjacent equatorial LV regions located more anteriorly (ANT) and laterally (LAT). We found that the magnitudes of LAT normal longitudinal and radial strains, as well as major principal strains, were less than ANT, while those of PAP were intermediate. Subepicardial and midwall myofiber angles of LAT, PAP, and ANT were not significantly different, but PAP subendocardial myofiber angles were significantly higher (more longitudinal as opposed to circumferential orientation). Subepicardial and midwall myofiber strains of ANT, PAP, and LAT were not significantly different, but PAP subendocardial myofiber strains were less. Transmural gradients in circumferential and radial normal strains, and major principal strains, were observed in each region. The two main findings of this study were as follows: 1) PAP strains are largely consistent with adjacent LV equatorial free wall regions, and 2) there is a gradient of strains across the anterolateral equatorial left ventricle despite similarities in myofiber angles and strains. These findings point to graduated equatorial LV heterogeneity and suggest that regional differences in myofiber coupling may constitute the basis for such heterogeneity. 相似文献
|