  Monitoring the activity of the heart is important for diagnosing and
preventing cardiovascular diseases. The electrocardiogram (ECG) is the gold
standard for diagnosing such diseases. It monitors the heart's electrical
activity, and while this is highly correlated with the cardiac mechanical
activity, it does not provide all the information. Other sensors such as the
echocardiograph are able to monitor the heart's movements, but such tools are
expensive and hard to operate. Therefore, contactless monitoring of the heart
using RF sensing has gained interest in recent years. In this paper, we
describe a process to extract the movements of the heart from millimeter wave
radar with high accuracy, and thus we provide a noninvasive and affordable way
to monitor cardiac movements. We then demonstrate the correlation between the
observed movements and the ECG. Furthermore, we propose an algorithm to
synchronize the ECG signal and the processed signal from the radar sensor. The
results we obtained provide insights on the mechanical activity of the heart,
which could assist cardiologists in their diagnoses.
