There is provided a system for monitoring a heart of a subject and monitoring impedance-related parameters, comprising: a feeding tube, an electrode disposed(s) on a distal end of the feeding tube, a controller that performs, while the feeding tube is in located in an esophagus and feeding is delivered to a subject via the feeding tube, in a plurality of iterations: continuously measuring voltage at the electrode(s) of the feeding tube, applying alternating current(s) between the electrode(s) of the feeding tube and at least one other electrode, computing impedance measurement(s) from the electrode(s) of the feeding tube according to the applied alternating current(s) and the measured voltage, computing impedance-related parameter(s) based on the impedance measurement(s), terminating the application of the alternating current(s), obtaining an electrocardiogram (ECG) measurement based on the voltage measured at the electrode(s) of the feeding tube, and providing the impedance-related parameter(s) and the ECG measurement.