The following situations make it impossible to perform CT angiography:
In special situations, we may study patients with a creatinine up to 1.9 or Agatston scores >1500. Such patients require the approval of the cardiologist in charge prior to scheduling.
Optimal image quality requires a HR <65 and most patients are pre-medicated with beta blocker. If possible and not contraindicated, we prefer the patient be prescribed metoprolol 50 mg po qhs and 2 hrs prior to exam.
When this is logistically impossible, we have the patient come 1.5 hrs before the schedule test, check the heart rate and any possible contraindications, give the patient metoprolol 50-100 mg po, and have them wait in our lobby for 1 hr before proceeding.
If neither method has achieved optimal heart rate, we may give the patient up to 25 mg of additional metoprolol IV prior to imaging.
Unless contraindicated all patients are given sublingual nitroglycerin spray for maximal coronary dilation immediately prior to testing.
Typical radiation doses for a CT coronary angiogram and other common tests are as follows: