<unk>  is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis.
Pulsus alternans
Pulsus paradoxus
Pulsus parvus et tardus
Muffled heart sounds
Pulsus bigeminus
Irregular pulse
Binaural beats
Precordial thump