Echocardiographic Weaning in Temporary Mechanical Circulatory Support: The Role of LVOT VTI

Abstract

Purpose With ongoing research, there is still absence of robust evidence-based recommendations describing use and clinical impact of daily echocardiographic evaluation for mechanically unloaded patients supported with either temporary micro-axial flow (Impella) or intra-aortic balloon counterpulsation (IABP) pumps. Our hypothesis is that in such patients, adjunct protocolized bedside echocardiographic weaning evaluation offers a reliable surrogate of myocardial performance prior to explant. Methods Our description included retrospective evaluation of a database of patients supported with Impella (CP/5.0) or IABP at the Baystate Medical Center Cardiac ICU from 2014 to 2017. Patients included had 1) clinical and hemodynamic cardiogenic shock, 2) prolonged Impella/IABP support requiring ICU level of care, and 3) serial LVOT VTI and cardiac index (CI) checks during support. We excluded patients with intraprocedural Impella insertion/removal. Results were plotted for a total of 80 LVOT VTI and corresponding CI values recorded spanning the implant-explant time. We plotted 3 correlation graphs for VTI to CI (Fig.1), iVTI (indexed LVOT VTI to patients' body surface area) to CI (Fig.2), and rVTI to rCI (relative LVOT VTI and CI to their initial values recorded following implant) (Fig.3). Results Results showed a positive regression of 0.6 for VTI/CI, 0.58 for iVTI/CI, and 0.77 for rVTI/rCI (p-value Conclusion As our data indicates, we provide a real-world standardized method that objectively focuses on routine evaluation of LVOT VTI as a surrogate of myocardial performance in cardiogenic shock requiring prolonged mechanical unloading. This method should therefore be taken one step further and considered for daily assessment of myocardial performance while weaning the support settings, as illustrated in our example (Fig.4), and be protocolized as a standard weaning parameter in shock centers.