Abstract: An apparatus and method for detecting myocardial ischemia in a subject monitors the systemic vascular resistance of the subject and detects the presence of myocardial ischemia when the systemic vascular resistance increases by at least sixty percent over a base line value. Particular apparatus describe providing a measurement corresponding to the systemic vascular resistance of the cardiovascular system. A particular invasive pressure measuring apparatus uses a flexible catheter tube insertable into the artery of the subject and a micro-manometer embedded into the outer face of the wall of the catheter tube. The outer face of the embedded micro-manometer is directly exposed to the blood in an artery and the inner face of the embedded micro-manometer is covered by the inner face of the catheter tube wall.

Abstract: A method and apparatus monitor myocardial ischemic events in various medical applications for providing continuous and contemporaneous information regarding, for example, modifying the amount of medication for a patient, determining response during (PTCA) balloon angioplasty, monitoring the onset of myocardial ischemic events during induction of anesthesia, determining painless myocardial ischemia in a resting patient, and monitoring the onset of myocardial ischemic during stress conditions in a patient. The method and apparatus also provide a calibration method for determining from a Resistive Index and using the resulting transformation for calculating, on a continuing basis, both systemic vascular resistance and cardiac output.

Abstract: In the described method and apparatus for examining a subject's cardiovascular system, a blood-pressure signal having a waveform varying in accordance with the subject's arterial pressure is differentiated to produce a dP/dt signal having a waveform varying in accordance with the rate at which the blood-pressure signal varies. The pressure at the time of the peak dP/dt signal is detected and is divided by the dP/dt signal to produce a measurement corresponding to the systemic vascular resistance. The latter measurement is then multiplied by a resistance factor corresponding to the physical resistance characteristic of the particular cardiovascular system examined. A measurement of the cardiac output may also be produced by subtracting, from the mean arterial pressure of the subject, the subject's central venous pressure and dividing the latter by the systemic vascular resistance.