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. Experiments were performed on anaesthetized, artificially ventilated, closed-chest dogs, into which five catheters and probes had been inserted.