Polyurethane sheath disintegration causing impaction of pacer lead and shock during attempted removal.

Steady traction to remove a lead whose polyurethane sheath had disintegrated caused displacement of the heart and caused hypotension; the bared lead uncoiled and impacted in the wall of the subclavian vein. The tension on the intrathoracic lead was relieved via immediate anterior thoracotomy and compartmentalization of the superior vena cava.