A cardiac medical device, comprising: a first sensor to sense a test signal, the test signal being sensitive to contraction of a diaphragm of a patient; a second sensor to sense a predetermined cardiac signal; and a processor operably coupled to the first sensor and the second sensor and configured to: determine signal artifacts of the test signal within each of a first window of the test signal prior to a predetermined cardiac signal and a second window of the test signal subsequent to the predetermined cardiac signal, determine, in response to signal artifacts of the test signal within the first window and the second window, whether phrenic nerve stimulation beat criteria have been satisfied, determine, in response to the PNS beat criteria being satisfied, whether PNS episode criteria have been satisfied, and detect a PNS episode in response to the PNS episode criteria being satisfied; and characterized in that the processor is further configured to: determine signal artifacts of the test signal within a third window of the test signal subsequent to the predetermined cardiac signal and different from the second window, and determine, in response to signal artifacts of the test signal within the third window, whether noise criteria have been satisfied. a first sensor to sense a test signal, the test signal being sensitive to contraction of a diaphragm of a patient; a second sensor to sense a predetermined cardiac signal; and a processor operably coupled to the first sensor and the second sensor and configured to: determine signal artifacts of the test signal within each of a first window of the test signal prior to a predetermined cardiac signal and a second window of the test signal subsequent to the predetermined cardiac signal, determine, in response to signal artifacts of the test signal within the first window and the second window, whether phrenic nerve stimulation beat criteria have been satisfied, determine, in response to the PNS beat criteria being satisfied, whether PNS episode criteria have been satisfied, and detect a PNS episode in response to the PNS episode criteria being satisfied; and determine signal artifacts of the test signal within each of a first window of the test signal prior to a predetermined cardiac signal and a second window of the test signal subsequent to the predetermined cardiac signal, determine, in response to signal artifacts of the test signal within the first window and the second window, whether phrenic nerve stimulation beat criteria have been satisfied, determine, in response to the PNS beat criteria being satisfied, whether PNS episode criteria have been satisfied, and detect a PNS episode in response to the PNS episode criteria being satisfied; and characterized in that the processor is further configured to: determine signal artifacts of the test signal within a third window of the test signal subsequent to the predetermined cardiac signal and different from the second window, and determine, in response to signal artifacts of the test signal within the third window, whether noise criteria have been satisfied. determine signal artifacts of the test signal within a third window of the test signal subsequent to the predetermined cardiac signal and different from the second window, and determine, in response to signal artifacts of the test signal within the third window, whether noise criteria have been satisfied.