A needle for a medical procedure includes a shaft with an inner surface, an outer surface, a proximal section, and a distal section. The distal section has a conductive tip configured to be a first electrode for voltage measurement. The needle further includes a first electrically insulative outer layer over a portion of the outer surface of the shaft. The conductive tip is adapted for insertion through tissue into, for example, a pericardial space of a patient. A system for determining the location of a needle during a medical procedure includes the needle and an anatomical mapping and localization system electrically coupled to the needle and adapted to measure voltage at the conductive tip. A system for determining tissue thickness during a medical procedure includes the needle, an anatomical mapping and localization system electrically coupled to the needle, and an electrocardiograph operatively coupled to the needle and adapted to monitor electrical activity at the conductive tip and at the second electrode. The needle may include a second electrode.
