 After proving that his new discoveries were superior to established methods, he had to defend them when other techniques emerged.A sampling of controversies that engulfed Paul Zoll include his technique of closed chest resuscitation versus open chest rescue; his application of alternating current countershock versus direct current cardioversion; and his preference for open chest long-term lead placement versus transvenous lead placement.Paul Zoll was helped by several colleagues who shared his goals and worked by his side.