[ Steve's own heartbeat is fluttering, irregular -- it's always been like this; and it's not new when he's fighting against his own body for his life every day.

Bucky's hand on his chest still startles him, but it's only a moment after that that he relaxes, watching him easily, not moving his hand. Wryly, he comments. ] You used to do that. You'd put your ear on my chest to make sure that I wasn't giving up the ghost. [ He shrugs a little. ] Sometimes my heart rate gets messed up.