Monitoring a Mystery: The Unknown Right Ventricle during Left Ventricular Unloading with Impella in Patients with Cardiogenic Shock.

Background : Right ventricular (RV) dysfunction or failure occurs in more than 30% of patients in cardiogenic shock (CS). However, the importance of timely diagnosis of prognostically relevant impairment of RV function is often underestimated. Moreover, data regarding the impact of mechanical circulatory support like the Impella on RV function are rare. Here, we investigated the effects of the left ventricular (LV) Impella on RV function. Moreover, we aimed to identify the most optimal and the earliest applicable parameter for bedside monitoring of RV function by comparing the predictive abilities of three common RV function parameters: the pulmonary artery pulsatility index (PAPi), the ratio of right atrial pressure to pulmonary capillary wedge pressure (RA/PCWP), and the right ventricular stroke work index (RVSWI). Methods : The data of 50 patients with CS complicating myocardial infarction, supported with different flow levels of LV Impella, were retrospectively analyzed. Results: Enhancing Impella flow (1.5 to 2.5 L/min ± 0.4 L/min) did not lead to a significant variation in PAPi ( p = 0.717), RA/PCWP ( p = 0.601), or RVSWI ( p = 0.608), indicating no additional burden for the RV. PAPi revealed the best ability to connect RV function with global hemodynamic parameters, i.e., cardiac index (CI; p < 0.001, 95% CI: 0.181-0.663), pulmonary capillary wedge pressure (PCWP; p = 0.005, 95% CI: -6.721--1.26), central venous pressure (CVP; p < 0.001, 95% CI: -7.89-5.575), and indicators of tissue perfusion (central venous oxygen saturation (SvO2 ); p = 0.008, 95% CI: 1.096-7.196). Conclusions: LV Impella does not impair RV function. Moreover, PAPi seems to be to the most effective and valid predictor for early bedside monitoring of RV function.