Noninvasive Estimation of Left Ventricular End-Diastolic Pressure Through a Mechanical Seal for a Rotary Blood Pump

Left ventricular end-diastolic pressure (LVEDP) is an important index of cardiac preload and heart failure (HF) severity. However, direct measurement of LVEDP requires invasive procedures, including local anesthesia and catheter insertion. To address these limitations, we developed a novel LVEDP estimation method based on the relationship between left ventricular pressure and the behavior of the mechanical seal (MS). In this study, we demonstrate that LVEDP can be estimated by measuring pressure inside the MS.

Rotating parts of the RBP, consisting of an impeller, a seal ring, and other components, are supported by a seat ring, while the seal ring is nearly in contact with the seat ring. The clearance width between the rings is determined by the balance of forces acting on the rotating parts, and MS opening occurs when this balance is changed. First, a static test was conducted to evaluate the relationship between MS opening pressure (MSOP) and RBP inlet pressure. Subsequently, a dynamic test using a pulsatile simulator was performed to confirm whether this relationship remains valid under physiological conditions.

The static test demonstrated that MSOP is proportional to the RBP inlet pressure. In the dynamic test, MS openings were observed only during diastole, and MSOP showed a strong correlation with LVEDP.

Our method successfully estimated LVEDP in a completely noninvasive manner by utilizing the mechanical seal structure of the RBP.