Model-Free markers of cardiovascular and cerebrovascular controls in surgical and transcatheter aortic valve replacement patients

Transcatheter aortic valve implantation (TAVI) is nowadays more frequently considered as an alternative to traditional surgical aortic valve replacement (SAVR) for patients affected by severe aortic valve stenosis (AVS). The impact of both procedures on cardiovascular (CV) and cerebrovascular control (CBV), as derived from time series analysis of heart period (HP), systolic arterial pressure (SAP), mean arterial pressure (MAP), and mean cerebral blood velocity (MCBv), is still under debate. Model-free causality techniques based on k-nearest-neighbor unpredictability (KNNUP) can be exploited to investigate the strength of the CV interactions from SAP to HP and vice versa, and of CBV interactions from MAP to MCBv and vice versa. KNNUP markers were assessed in two groups of AVS patients scheduled for SAVR (n=19, age 76.8+3.1 yrs, 8 males) and for TAVI (n=19, age 79.9+6.5 yrs, 11 males) before (PRE) and after (POST) the intervention. We found that: i) CV control was impaired in SAVR patients in POST from SAP to HP, while it was maintained in TAVI; ii) CBV control from MAP to MCBv was not affected by both procedures. Model-free causality markers were able to characterize the impact of SAVR and TAVI in AVS population.