Overall myocardial energetics in physiological conditions and in acute volume overloading.

Left ventricular heat production (PH,lv) was compared with myocardial O2 consumption (P met O2) and mechanical parameters in intact anaesthetized dogs before and after acute volume overload induced by a perfusion of LMW dextran. From myocardial blood flow and coronary arterio-venous temperature differences, the coronary heat loss was determined. Thermodilution techniques were used to estimate the ratio between heat carried away by the coronary system and total heat production as the left ventricular volumes.

Imaging mammalian tissues and organs using laser collimated transillumination.

Images of mammalian organs were built up using a Laser collimated transillumination device equipped with a bidirectional scanning setup. A microcomputer was used to run the scanning process, acquisition of detected signals and images restitution. The images featured a satisfactory resolution of optical discontinuities on both sample surfaces.

A simulation method for the study of laser transillumination of biological tissues.

The Monte-Carlo method is employed to simulate the illumination of a blood slab by a continuous laser. It is assumed that the geometry of the medium is bidimensional and that scattering or absorption takes place only when a photon strikes a red blood cell. The parameters involved in the calculations concern the photons free path lengths between two collisions, the scattering angles and the absorption probability at collision.

A hybrid device for measurement of left ventricular heat production.

The presented hybrid system allows precise temperature measurements in various sites of the circulation, from the acquisition and preprocessing of dilution curves. From haemodynamic data and left ventricular heat production, an in situ estimate of left heart efficiency is made available. A simplifying hypothesis allows the determination of total left ventricular heat production from three data inputs: (1) the coronary sinus blood flowrate, (2) the thermal coronary veno-arterial difference, (3) the ratio of thermodilution curves areas recorded in the aortic root and the coronary sinus, following a rapid injection in the left ventricular cavity of cold isotonic glucose.

Determination of left ventricular heat production in working dog heart.

1 degree Total left ventricular heat production was reliably estimated from the coronary blood flow, the coronary arteriovenous thermal difference and the thermodilution curve areas recorded in aortic root and in coronary sinus after injection of cold glucose solution into the left ventricular cavity. The assumption was made that the distribution of a cold solution, purposely introduced into the coronary arteries, obeys the same law as the heat generated by the myocardium. 2 degrees Temperature measurements were achieved with thermistors and a linear ohmmeter.

Changes of the kinetics of calcium washout from dog heart after ischaemia.

The kinetics of myocardial calcium washout using a calcium free perfusion were studied in controls and animals after a short period of ischaemia. A significantly higher rate for k3 was found after ischaemia. This may represent a greater lability of membrane-bound calcium.

Biochemical heterogenity of the left ventricular myocardium: transmural and base-apex gradients on H.E.P. contents of the well oxygenated perfused dog heart.

An investigation into the contents (mumol/g w.w.) of the creatine phosphate (CP) and adenosine triphosphate (ATP) of various myocardial regions was performed on the empty beating isolated blood perfused dog heart.