Synergistic dynamics of heart rate variability and systolic blood pressure revealed by dual Poincaré plot analysis

Cardiac arrest (CA) survivors often suffer secondary brain injury due to impaired autonomic nervous system (reflected by heart rate HR) and hemodynamic function (reflected by blood pressure BP and baroreflex regulation). This study proposes a Dual Poincaré Plot, a novel method analyzing coupled variability in HR - BP dynamics to assess these impairments. Ten rats were categorized into good and poor neurological outcome groups in a rat model of CA. Dual Poincaré plot analysis, squared partial directed coherence, and sequence method were used to characterize the outcome. Results revealed differences in variability of HR, BP, and baroreflex, as well as coupling strength, between groups. Good outcome subjects exhibited 1) increased variability in both BP and HR, 2) enhanced baroreflex regulation, and 3) weakened cardiovascular coupling. Conversely, subjects with poor outcomes displayed 1) decreased HR-BP variability, 2) impaired baroreflex, and 3) stronger coupling. The Baroreflex Index from the Dual Poincaré plot showed a high correlation with the traditional sequence method (R² = 0.91). These results imply that Dual Poincaré offers a real-time assessment of autonomic-hemodynamic interaction, effectively stratifying post-CA neurological recovery and potentially enhancing prognostic accuracy for timely interventions.