Log files analysis and evaluation of circadian patterns for the early diagnosis of pump thrombosis with a centrifugal continuous-flow left ventricular assist device

Background: No clinical standardized methods exist to identify the early stage of the development of pump thrombosis in the setting of HVAD (Medtronic Inc., USA) implantation. We aimed at developing a clinically relevant tool to evaluate HVAD operation during long-term support and at identifying a new reliable marker for the early diagnosis of pump thrombosis reflecting altered patient-pump physiological interplay.

Methods: We developed a novel algorithm based on time-frequency analysis of the HVAD log files allowing the detection of the intrinsic circadian rhythmicity of the pump power consumption. With this tool, we retrospectively evaluated (1) post-operative restoration of circadian rhythm (n = 14 patients), (2) long-term stability of circadian rhythmicity in patients with no reported adverse events (n = 12), and (3) alteration of circadian fluctuations in patients who suffered from pump thrombosis (n = 19).

Results: We demonstrate (1) progressive development of circadian rhythm following post-operative recovery (93% of the patients, 23 ± 15 days after implantation), (2) long-term stability of circadian rhythmicity in patients with no thrombotic complications (92% of the patients; 962 (445-1447) days of support), and (3) severe instability and loss of circadian fluctuations before the thrombotic event (89% of the patients, 12 ± 6 days ahead of the clinical manifestation of overt pump thrombosis). Furthermore, we provide the first clinical evidence of recovery of circadian rhythmicity following non-surgical resolution of pump thrombosis.

Conclusions: Time-frequency analysis of the HVAD log files provides a new tool for the early diagnosis of pump thrombosis. Loss of circadian rhythmicity might trigger medical evaluation, improving the results of medical management of pump thrombosis, and decreasing the need for pump exchange.