Nuclear Cardiology: Nuclear Cardiology:

40 Nuclear Cardiology, The Basics• Patients are allowed to drink fruit juices, white milk, or water.• Patients should be off theophylline-based medications for 48 h prior tothe test. This should be done in consultation with the referringphysiciansThe reason for these instructions is that caffeine is a specific blockerof adenosine receptors and makes dipyridamole or adenosine infusionineffective and will likely result in false-negative tests. (See Table 4-1.)It is not rare that a patient’s exercise capacity is overestimated and theyneed to be switched to pharmacological stress. Therefore, as noted previously,it is advisable to give the same instruction about abstinence ofcaffeine-containing beverages and food to all scheduled patients.• The patient should be nil per os (NPO) 4 h prior to stress. Patients withdiabetes may eat a light meal (but no chocolate) and take theirmedications.• Patients should continue their other medications unless directed otherwiseby their physician.Rest Tc-99m-Agent (Tc-99m-Sestamibior Tc-99m-Tetrofosmin) First• The instructions are the same as for the “stress-first” procedure. However,the patients may eat a light breakfast or a light lunch if time permitsbefore rest study. Patients should be NPO 4 h prior to stress.• Patients should be off theophylline-based medications for 48 h followingtheir physicians advice.Stress/Redistribution Tl-201• Prior to the test the instructions are the same as for the “stress-first”procedure.• Between the stress and redistribution part of the procedure, thepatient may take liquids but no solid food. Caffeine is allowed afterthe stress portion. Diabetics may eat a light meal if needed.The reason for this instruction is that ingestion of food after stressinhibits the redistribution of Tl-201and defects may appear falsely fixed.Dual Isotope Rest-Thallium Stress-Tc-99m-Agent(Tc-99m-Sestamibi or Tc-99m-Tetrofosmin) Imaging• The instructions are the same as for the “rest-first” procedure. Thepatients may eat a light breakfast or a light lunch if time permits beforeRest study. Patients should be NPO 4 h prior to stress.