The dynamic geometry of the left ventricle was assessed with the use of chronically implanted pulse-transit ultrasonic dimension transducers. The orientation of the transducers allowed the measurement of left ventricular minor and major axis diameters and equatorial wall thickness in the conscious dog. The left ventricle was modeled as a three-dimensional, prolate ellipsoidal shell. Left ventri...

OBJECTIVE Overexpression of decorin reduces neointimal thickening in balloon-injured carotid arteries of rats by decreasing the volume of neointimal extracellular matrix (ECM). We examined the hypothesis that decorin regulates ECM volume by stimulating cell-mediated contraction of collagen-rich ECMs. METHODS AND RESULTS Rat arterial smooth muscle cells (ASMCs) transduced with bovine decorin c...

PURPOSE It has been tacitly assumed that overall extraocular muscle (EOM) volume is conserved during contraction and relaxation, yet this assumption has been untested up to now. We used high-resolution magnetic resonance imaging (MRI) to determine if total EOM volume changes during relaxation and contraction. METHODS Surface coil MRI in quasi-coronal planes was obtained in target-controlled, ...

Instantaneous left ventricular dynamics were measured from cineradiographs utilizing implanted tantalum coils as myocardial site markers in the orthotopically transplanted canine heart. Four parameters of myocardial synergy were obtained: mean shortening, anisotropy of contraction, mean time to half shortening, and asynchrony of contraction. Estimates of end diastolic volume, end systolic volum...

We investigated the spleen volume changes as related to the cardiovascular responses during short-duration apneas at rest. We used dynamic ultrasound splenic imaging and noninvasive photoplethysmographic cardiovascular measurements before, during, and after 15-20 s apneas in seven trained divers. The role of baroreflex was studied by intravenous bolus of vasodilating drug trinitrosan during tid...

Maintenance of metabolic alkalosis generated by chloride depletion is often attributed to volume contraction. In balance and clearance studies in rats and humans, we showed that chloride repletion in the face of persisting alkali loading, volume contraction, and potassium and sodium depletion completely corrects alkalosis by a renal mechanism. Nephron segment studies strongly suggest the correc...

SUMMARY The instantaneous response of the left ventricle to loss or recoverv of effective atrial contraction was studied in 12 patients with valvular aortic stenosis by producing A-V dissociation by electrical pacing of the ventricles so that some ventricular contractions were preceded by an effective atrial contraction while others were not. A conventional hydraulic formula relatinig size of t...