Abstract : Introduction: One of the important challenges after cardiac arrest (CA) is the neurological damage of the brain. In case of resuscitation after CA, the brain suffers the ischemia and the inflammation from reperfusion. To days, the only therapy available is the mild therapeutic hypothermia (MTH) : put the patient under 34°C-32°C during 12-24 hours. Even though that MTH has been shown to increase the hospital survival rate, it has many adverse effects, among which the cardiac arrhythmia generation represents an important part (up to 34%). Cardiac culture in vitro provides a better spatial resolution (to cellular level) than study in vivo, which could bring some insights of the mechanism of post-hypothermia arrhythmia generation. Method: Monolayer cardiac culture is prepared with cardiomyocytes from new-born rat (1-4 days) directly on the MEA at 37°C. The experiments consist of culture cooling (37°C-30°C) and re-warming (30°C-37°C). The acquired signals are then analyzed with detrended fluctuation analysis, phase space reconstruction, principle component analysis. Results: At 35°C, Spiral waves are observed in the reconstructed activation map which is commonly considered as a sign of cardiac arrhythmia. Between 35°C-33°C, the signals became regular. However, another transit point is found between 30°C-33°C. At 35°C, period-doubling phenomena are observed, which can be translated as a transit point from normal state to chaos state, from the point view of nonlinear dynamics. From the reconstructed phase space, doubling-trajectories and rare tripling-trajectories are found. It implies that the general dynamics of MTH could be presented as a pitchfork bifurcation, which could explain exactly the doubling-trajectories and tripling-trajectories phenomena. These results at cellular level agreed with other clinical studies on MTH. Conclusion: The general hypothermia therapy uses constant cooling or re-warming. Results in this study showed that a variable speed would help to reduce the rate of post-hypothermia arrhythmia.