A network of electrodes configured to sense and/or pace the heart, wherein the network of electrodes are in contact with an epicardial surface of the heart, within a wrapping sleeve that assist the heart as a whole, wherein the network of electrodes sense the heart by quantifying intrinsic electrical activities of the heart, and wherein the network of electrodes pace the heart by inducing an electrical impulse to the heart to control its contractile activities. The network may be interfaced with a controller system, wherein the controller uses spatial and temporal electrical activities of the heart muscles to generate electrical impulse to synchronize the wrapping sleeve around the heart with the heart. Also disclosed is a system configured to construct space-time mapping of cardiac electrical activities and/or propagation, and sensing effects of a first assist event of a prior beat and controlling a second assist event.