General manager Mike Rizzo says Martinez had a minor cardiac catheterization Monday in Washington.
Martinez, who turns 55 on Sept. 26, experienced chest pains during Washington's home game Sunday against Atlanta, left in the sixth inning and was taken to a hospital.
Bench coach Chip Hale will manage the Nats during the absence of Martinez. Hale said Martinez texted him Monday's starting lineup.
First base coach Tim Bogar will be in the dugout and assistant hitting coach Joe Dillon will replace Bogar at first.
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