Background Central aortic pressures and waveform convey important information about cardiovascular status, but direct measurements are invasive. Peripheral can be measured noninvasively, although they often differ substantially from central pressures, may mathematically transformed to approximate the latter. We tested this approach, examining intersubject intrasubject variability validity of using a single averaged transformation, which would enhance its applicability. Methods Results...

BACKGROUND It has been well established that arterial stiffness, manifest as an increase in pulse wave velocity or late systolic amplification of the carotid artery pressure pulse, increases with age. However, populations studied prior investigations were not rigorously screened to exclude clinical hypertension, occult coronary disease, diabetes. Furthermore, it is unknown whether exercise capacity chronic physical endurance training affects age-associated stiffness. METHODS AND RESULTS...

Echocardiograms were performed on 105 male participants in the National Institutes Aging's volunteer Longitudinal Study Program. All subjects (25--84 years of age) physically active and had no evidence hypertension or cardiovascular disease. Measurements made initial diastolic (E-F) slope anterior mitral valve leaflet, aortic left ventricular cavity dimensions, thickness posterior wall. Fractional shortening minor semi-axis ventricle velocity circumferential fiber also determined. It was...

Our objective was to validate a carotid artery tonometry-derived augmentation index as means estimate (AI) of ascending aortic pressure under various physiological conditions. A total 66 patients (50 men, 16 women; mean age, 55 years; range, 21 78 44 in Taiwan and 22 the United States) undergoing diagnostic catheterization were studied. Arterial contours obtained simultaneously from right common by applanation tonometry with an external micromanometer-tipped probe aorta catheter at baseline...

Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that is constant, i.e., pressure-volume (P-V) relations are linear, and they also diastolic aortic pressure decay an exponential function time. Both these assumptions, however, questionable. This study proposes improved based on a Windkessel model the system but which utilize area under tracing rather than waveform itself. Formulations accounting both...

The value of increased arterial wave reflection, usually assessed by the transit time–dependent augmentation index and augmented pressure (Pa), in prediction cardiovascular events may have been underestimated. We investigated whether time–independent measures reflected magnitude predict outcomes independent stiffness indexed carotid-femoral pulse velocity. A total 1272 participants (47% women; mean age: 52±13 years; range: 30 to 79 years) from a community-based survey were studied. Carotid...

Fluctuations in body weight as occur with aging make an unreliable reference for normalizing heart weight. We compared normalized by tibial length, which remains constant after maturity, that 5- to 28-mo-old male Wistar rats. When length or weight, relative the 5-mo heart, senescent left ventricle undergoes 17 vs. 38% hypertrophy, respectively, and right 0 28% respectively. Histological measurements 25- 5-mo-old ventricles reveal 6% larger myocyte diameters 12% cellular cross-sectional...

Indentation using the atomic force microscope (AFM) has potential to measure detailed micromechanical properties of soft biological samples. However, interpretation results is complicated by tapered shape AFM probe tip, and its small size relative depth indentation. Finite element models (FEMs) were used examine effects indentation depth, tip geometry, material nonlinearity heterogeneity on finite response. Widely applied infinitesimal strain agreed with FEM for linear elastic materials, but...

The constitutive law of the material comprising any structure is essential for mechanical analysis since this enables calculation stresses from deformations and vice versa. To date, there no actively contracting myocardial tissue. Using 2,3-butanedione monoxime to protect myocardium trauma, we subjected thin midwall slices rabbit multiaxial stretching first in passive state then during steady-state barium contracture or tetani ryanodine-loaded Assuming transverse isotropy both active...

Biaxial mechanical testing and theoretical continuum mechanics analysis are employed to formulate a constitutive law for cardiac mitral valve anterior posterior leaflets. A strain energy description is formulated based on the fibrous architecture of tissue, accurately describing large deformation, highly nonlinear transversely isotropic material behavior. The results show that simple three-coefficient exponential provides an accurate prediction stress–stretch behavior over wide range...

Anterior and posterior leaflets from excised porcine mitral valves were mechanically tested under cyclic equibiaxial strip biaxial stretch protocols at a strain rate of 4-12%/s after preconditioning. Cauchy stress Lagrangian calculated for both membrane three-dimensional cases. The exhibited nonlinearly elastic, anisotropic behavior. Both anterior less extensible in the circumferential than radial direction stretch, with ratios 5.7 4.3, respectively. greater extensibility directions lower...

Intra-aortic balloon counterpulsation is capable of reducing afterload in patients with unstable angina. Whether it also augmenting coronary blood flow to poststenotic myocardium controversial. We studied seven receiving maximal drug therapy and requiring pumping for angina as volume assist ratio were altered. All had greater than 90% stenosis the proximal left anterior descending artery. With augmentation (40 cc volume, 1:1 ratio) great cardiac vein flow, representing efflux from artery...

Differences in aortic impedance between normotensives and hypertensives are not well characterized. We examined 8 normotensive 11 hypertensive (mean 96.7 vs. 122.2 mmHg) age-matched, Chinese patients undergoing cardiac catheterization at rest, during nitroprusside, handgrip exercise before after beta blockade (propranolol). Hypertensives had higher resistance (2,295 1713 dyn-s/cm5), characteristic (145.7 93.9 total external power (1,579 1174 mW), peripheral reflections (ratio of backward to...

Although it has been proposed that incomplete relaxation explains certain increases in left ventricular end diastolic pressure relative to volume, there no clear demonstration occurs the intact working ventricle. To identify relaxation, pressure-dimension relationships were studied 10 canine right heart bypass preparations during pacing. The fully relaxed, exponential line for each ventricle was first determined from and dimension values at of prolonged diastoles after interruption For 167...

Abstract We conducted this study to compare the effects of fosinopril versus atenolol on peripheral blood pressure, central arterial wave reflection, and left ventricular mass in a group patients with essential hypertension. double-blind, randomized trial 79 hypertensive (52 men, 27 women; mean age, 45.8±8.5 years; range, 30 68 years). Carotid pressure waveforms were recorded noninvasively by applanation tonometry Millar micromanometer-tipped probe. The extent reflection was estimated...

Abstract Intracellular tension is considered an important determinant of cytoskeletal architecture and cell function. However, many details about remain poorly understood because these forces cannot be directly measured in living cells. Therefore, we have developed a method to characterize the magnitude distribution pre‐extension actin stress fibers (SFs) due resting cytoskeleton. Using custom apparatus, human aortic endothelial cells (HAECs) were cultured on pre‐stretched silicone substrate...

We studied the function of right internal jugular vein valves during cardiac catheterization in 32 patients and external vitro from 13 dogs. Patients with normal central venous pressure had competent cough-induced transvalvular gradients 52.4 +/- 8.6 mm Hg. Ten 15 elevated either incompetent or absent valves, latter occurring only long-standing, severe tricuspid regurgitation. During coughing, were also demonstrated left subclavian veins. The excised canine at a static 81.8 3.7 Five six...

Abstract This article reviews our work on the effects of different classes antihypertensive agents hemodynamic alterations in essential human hypertension. Short-term studies were done during cardiac catheterization young normotensive subjects (mean age, 33 years; range, 19 to 40) and several age-matched (range, 25 53 years) groups patients with Aortic impedance, resistance, wave reflections, compliance calculated from high-fidelity recordings ascending aortic pressure flow signals baseline...

Aortic compliance in normotensive and hypertensive Chinese subjects undergoing diagnostic cardiac catheterization was compared by using a newly described method that allows for determination of the pressure dependence if one assumes value exponential coefficient pressure-volume relation large arteries. Under baseline conditions groups at mean aortic pressures 96.3 128.6 mm Hg, averaged 1.47 0.80 ml/mm respectively. Compliance group diastolic 99.4 Hg (which nearly equal to pressure) 1.072...

Arterial aging may link cardiovascular risk to white coat hypertension (WCH). The aims of the present study were investigate role arterial in effect, defined as difference between office and 24-hour ambulatory systolic blood pressures, compare WCH with prehypertension (PH) respect target organ damage long-term mortality. A total 1257 never-been-treated volunteer subjects from a community-based survey studied. PH by pressures. Left ventricular mass index, carotid intima-media thickness,...