Justice Ruth Bader Ginsburg had stent placed in her heart

Supreme Court Justice Ruth Bader Ginsburg underwent heart surgery Wednesday morning in Washington, the high court said.

The 81-year-old was admitted to the MedStar Heart & Vascular Institute at the MedStar Washington Hospital Center after she experienced discomfort during routine exercise on Tuesday night. She underwent a coronary catherization procedure and is now reportedly resting comfortably in the hospital. According to the Supreme Court, she is expected to be discharged within the next 48 hours.

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For the past few years, Ginsburg has been working out with a personal trainer at the Supreme Court's official gym, and a court official said that's where she was last night when she experienced the discomfort.

Ginsburg, who is currently the oldest justice on the Supreme Court, has repeatedly resisted calls from progressives to consider stepping down so President Obama can nominate a like-minded judge to replace her. Ginsburg, who was nominated by President Bill Clinton and confirmed to the court nearly unanimously in 1993, has been the most stalwart representative of liberal positions on the hot-button issues the Supreme Court has faced.

Although she has occasionally cast a deciding vote, it has been her blistering dissents in cases like Citizens United or Bush v. Gore that have earned her fans of all ages on the political left and won her the tongue-in-cheek moniker: Notorious R.B.G.

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In September, Ginsburg told Elle magazine that efforts to push her to resign were "misguided."

“Who do you think President Obama could appoint at this very day, given the boundaries that we have? If I resign any time this year, he could not successfully appoint anyone I would like to see in the court,” Ginsburg told writer Jessica Weisberg. “[The Senate Republicans] took off the filibuster for lower federal court appointments, but it remains for this court.”