The correlation between the systolic time interval and abnormal contraction in ischemic myocardium was studied in anesthetized open-chest dogs. A strain-gauge was sutured on the surface of the left ventricular wall perfused by the left anterior descending coronary artery (LAD) for measuring segment-length. The left ventricular stroke volume decreased progressively after occlusion of LAD. The le...

left atrial (la) distension has been demonstrated to be linked with aortic stiffness in different patient populations. three-dimensional (3d) speckle-tracking echocardiography (ste) seems to be a promising tool for volumetric and functional evaluation of the la. the aim of the present study was to determine whether correlations exist between 3dste-derived la volume-based and strain parameter...

When one is interested in the study, particularly the screening, of cardioactive agents, one needs to have the information on the effects of the concerned drug on (i) the rate, (ii) rhythm, (iii) force of contraction and (iv) output of the heart. The methods commonly used to study the effects of drugs on the heart in situ are Cushny's myocardiograph, glass cardiometry and electrocardiography (3...

Numerical simulations of PTT fluids in axisymmetric sudden contractions were carried out to investigate the effect of contraction ratio on the flow patterns under conditions of negligible inertia. The PTT model selected has a linear stress coefficient, and contraction ratios (CR) in the range 4:1 to 100:1 were investigated. The simulations are based on a finite volume methodology using very fin...

This article addresses the issue of reproducing quantitative pressure-drop predictions for constant shear-viscosity fluids in contraction and contraction/expansion flow geometries. Experimental observations on pressure-drop for severe strain-hardening Boger fluids reveal significant enhancement above Newtonian fluids in axisymmetric but not planar configurations. This discrepancy has eluded pre...

Pericardiophrenic attachments transmit diaphragm contraction to the pericardium. We investigated this in two ways. 1) We replaced the hearts of externally perfused dogs with a balloon from which we measured pressure changes. Diaphragm contraction increased pressure from 4.6 to 5.5 Torr, equivalent to an isobaric volume decrease of 1.5%, and decreased volumetric compliance by 3%. 2) We selective...

We studied the influence of aging on the contractile performance, stiffness, and contraction time of the canine left ventricle. Eight young (27 +/- 2.5 months, mean +/- SE) and seven old (128 +/- 20.5 months) beagles were placed on complete cardiopulmonary bypass, the arterial pressure was adjusted to 80 mm Hg, and the heart contracted isovolumically at a paced rate of 120 beats/min. Diastolic ...

BACKGROUND Left atrial three-dimensional shape and contraction patterns are not well described. We quantified the LA using three-dimensional cardiac MRI (CMR) in a group of normal subjects. METHODS Three-dimensional vectors were used to quantitate atrial shape and contraction using a geometric model as a three-dimensional prolate ellipsoid. Atrial area and length at end-systole and end-diasto...

The external anal sphincter (EAS) plays a critical role in maintaining fecal continence; however, cerebral cortical control of voluntary EAS contraction is not completely understood. Our aims were to determine the cortical areas associated with voluntary EAS contraction and to determine the effect of two levels of sphincter contraction effort on brain activity. Seventeen asymptomatic adults (ag...

We have examined the contribution of L-type Ca2+ current ( I Ca) to the activation of contraction in trout atrial myocytes under basal and phosphorylating conditions. The average myocyte length was 197 ± 14 μm, width was 5.5 ± 0.2 μm, and cell capacitance was 36.2 ± 2.2 pF. With 25 μM EGTA in the patch pipette and a stimulation frequency of 0.125 Hz, I Cawas 2.6 ± 0.4 pA/pF and it carried a tot...