Monitoring systemic ventriculoarterial coupling after cardiac surgery using continuous transoesophageal echocardiography and deep learning.

Abstract

Deterioration of ventriculoarterial coupling is detrimental to cardiovascular and left ventricular function. To enable continuous monitoring of left ventricular function, we have developed autoMAPSE, a new tool that combines transoesophageal echocardiography with deep learning for automatic measurement of mitral annular plane systolic excursion. We hypothesised that autoMAPSE could be used to monitor systemic ventriculoarterial coupling and detect alterations in postoperative cardiac biomarkers. To test this hypothesis, we monitored 50 patients for 120 min immediately after cardiac surgery by measuring autoMAPSE and mean arterial pressure (MAP) every 5 min. Postoperative N-terminal pro B-type natriuretic peptide (ProBNP) and high-sensitivity troponin-T (TnT) were measured twice daily until the evening of postoperative day 1. Ventriculoarterial coupling was assessed non-invasively by calculating arterial elastance and end-systolic elastance (Ea/Ees-ratio). The relationship between autoMAPSE and ventriculoarterial coupling was assessed by 1) correlating Ea/Ees-ratio with one simultaneous autoMAPSE measurement, and 2) relating the measurements of autoMAPSE with corresponding MAP within each patient using a linear mixed model with random slopes. We found that autoMAPSE correlated negatively with Ea/Ees-ratio (rho = - 0.61, P < 0.05). Furthermore, the individual slopes relating autoMAPSE to MAP were highly significant (P < 0.001) and markedly heterogeneous (both positive and negative), suggesting that ventriculoarterial coupling differs substantially in different individual patients. Finally, continuous autoMAPSE measurements were negatively correlated with both peak postoperative ProBNP (rho = - 0.46, P < 0.001) and TnT (rho = - 0.29, P < 0.05). In conclusion, continuous monitoring using autoMAPSE in the first two postoperative hours reflected ventriculoarterial coupling as well as peak ProBNP and TnT during the subsequent 24 h.