The "lead tug" sign for the diagnosis of early and inapparent lead fracture.

The cause of pacemaker malfunction in a patient having intermittent pacing failure associated with diminished pacer stimuli was not determined during conventional intraoperative electrical testing. A modest manual pull on the lead, termed the "lead tug" sign, induced an inordinately high lead impedance and established lead fracture as the etiology. The "lead tug" maneuver is proposed as a useful procedure during stimulation studies for the detection of early lead fracture, not apparent from the x-ray film or usual testing protocol.