The stress thallium and the cardio catheterization, in which dye is injected in the coronary arteries (arteries of the heart muscle) are both useful in telling us if there is any coronary artery disease.

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Today, the cardiologist said, she would get a stress test, an echocardiogram, a mobile Holter monitor, and maybe even a cardiac catheterization.

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Additional tests may include a nuclear stress test to assess for blockages in the coronary arteries, and if positive, a cardiac catheterization, an invasive test which involves threading a thin wire into the heart to assess for blockages in the coronary arteries as well.

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The CT scans, like the cardiac catheterization, utilize IV dye and can potentially damage the kidneys as well.

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Patients with a positive coronary CT scan would then require a cardiac catheterization, with possible angioplasty and stent placement.

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"This really is an insurance policy for him, " said Dr. Jonathan Reiner, Cheney's personal cardiologist and head of the hospital's cardiac catheterization lab.

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And if that passivity catches up with them, Carlin's satellite-linked EKG machine or a robotic catheterization lab might be just a 20-minute mule ride away.

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