Left ventricular intramyocardial pressure determination using two different solid-state micromanometric pressure sensors.

Intramyocardial tissue pressure can influence distribution of ventricular blood flow and dynamics during the cardiac cycle. Left ventricular ventral wall subepicardial and subendocardial tissue pressures were measured simultaneously using two different types of solid-state micromanometers (5F Millar model SPR-230 and Konigsberg Instruments model P19 pressure transducers) and compared with left ventricular cavity pressure. Systolic pressures recorded by Millar and Konigsberg transducers were similar when the sensor surfaces faced the left ventricular cavity either in the endocardium or epicardium. Diastolic pressures in the epicardium were higher than left ventricular cavity pressure. When Millar and Konigsberg transducer were placed in the epicardium, with the pressure sensors facing epicardially, the output signal of the Millar transducer was out of phase with the signal of the Konigsberg transducer and left ventricular chamber pressure outputs. Results indicate that output signals for intramyocardial pressures vary depending on the direction of the Millar or Konigsberg pressure sensor in the left ventricular wall. Thus, pressure output signals vary depending on configuration of the sensor surface, relative flexibility of the connecting cables, and orientation of the sensor surface with respect to left ventricular anatomy.