A system for postoperative visualization and analysis of left ventricular pressure-volume loops.

A patient monitoring system for continuous real-time monitoring of left ventricular (LV) function in the postoperative setting was developed. Common hemodynamic parameters and LV functional indices are all calculated from left ventricular pressure-volume loops (PV-loops). Visualization of the PV-loops, along with the hemodynamic parameter derived from them, provides valuable insight into ventricular function and patient recovery. The pressure component is obtained via a pressure sensing catheter placed during surgery. Volume is measured via non-imaging radionuclide techniques using a modified Capintec-VEST. Following surgery and transfer to the recovery unit, the patient's blood is labeled with Tc-99m. A portable gamma camera is used to measure baseline ejection fraction (EF) and to aid in placing the VEST. The specific radioactivity of the blood is calibrated using the baseline EF and thermodilution cardiac output. To confirm the volume measurement accuracy of this technique six patients undergoing bilateral heart catheterization were studied. Single-plane cineventriculographic LV volumes were compared to those calculated from the VEST's time activity curve.