What is the protocol for ordering a cardiac chemical stress test?

How to Order a Cardiac Chemical Stress Test

To order a cardiac chemical stress test, write a clear prescription specifying the vasodilator agent (preferably regadenoson), withhold beta blockers on the test day, and include relevant clinical information about the patient's cardiac history and reason for testing. 1, 2

Selecting the Appropriate Pharmacological Agent

Preferred Agents

• Regadenoson (Lexiscan): Single standard bolus dose of 0.4 mg IV over 10 seconds regardless of patient weight, followed by a 5 mL saline flush 3

  • Advantages: Shorter duration, fewer side effects, no need for weight-based dosing
  • FDA-approved and demonstrated similar efficacy to adenosine in clinical trials

• Adenosine: Infusion at 140 μg/kg/min over 4-6 minutes (maximum 60 mg) 1

  • Shorter half-life allows quicker resolution of side effects

• Dipyridamole: 0.84 mg/kg over 6-10 minutes 1

  • Longer duration of action (30 minutes)

• Dobutamine: Start at 5 μg/kg/min, increase by 5-10 μg/kg/min every 3 minutes to maximum 40-50 μg/kg/min 1

  • Used when vasodilators are contraindicated (e.g., severe asthma)

Pre-Test Patient Preparation Instructions

1. Medication Management:

   • Withhold beta blockers (e.g., atenolol) on the day of the test 2
   • For twice-daily dosing, skip both evening dose before and morning dose on test day
   • Withhold caffeine for 12-24 hours before the test 1
   • Withhold theophylline/aminophylline for 24 hours 4
   • Withhold dipyridamole for anti-platelet purposes 1

2. Fasting Requirements:

   • Light meal 4 hours before test
   • Water is permitted

Essential Elements of the Order

1. Patient Demographics:

   • Full name, DOB, medical record number
   • Height, weight, contact information

2. Test Specification:

   • "Pharmacological nuclear stress test with [specific agent]"
   • Specify imaging protocol (SPECT or PET)
   • Specify radioisotope preference if applicable

3. Clinical Information:

   • Primary indication for testing
   • Relevant cardiac history (prior MI, stents, CABG)
   • Risk factors (hypertension, diabetes, smoking, family history)
   • Current cardiac symptoms
   • Relevant medications (especially those affecting heart rate/BP)

4. Contraindications to Check:

   • For vasodilators: active bronchospasm, severe COPD/asthma
   • For dobutamine: uncontrolled hypertension, severe arrhythmias
   • For all: unstable angina, acute myocardial infarction, severe aortic stenosis

5. Special Instructions:

   • Note if patient has mobility issues requiring wheelchair
   • Indicate if aminophylline should be available for reversal of vasodilator effects
   • Note if interpreter is needed

Sample Order Template

CARDIAC NUCLEAR STRESS TEST ORDER

Patient: [Name], [DOB], [MRN]
Height: [x] cm  Weight: [x] kg

TEST REQUESTED:
☒ Pharmacological Nuclear Stress Test with Regadenoson
☐ Pharmacological Nuclear Stress Test with Adenosine
☐ Pharmacological Nuclear Stress Test with Dipyridamole
☐ Pharmacological Nuclear Stress Test with Dobutamine

INDICATION FOR TEST:
☐ Chest pain evaluation
☐ Abnormal ECG
☐ Pre-operative risk assessment
☐ Known CAD - evaluation for ischemia
☐ Other: _________________

RELEVANT CLINICAL INFORMATION:
- Cardiac history: 
- Current cardiac symptoms:
- Risk factors:
- Relevant medications:

PATIENT INSTRUCTIONS PROVIDED:
☒ Withhold beta blockers on day of test
☒ No caffeine for 24 hours before test
☒ Light meal permitted 4 hours before test
☒ Continue other medications with sips of water

ORDERING PROVIDER:
Name: _________________ Signature: _________________
Date: _________________ Contact: _________________

Common Pitfalls to Avoid

1. Failing to withhold interfering medications:

   • Beta blockers can blunt heart rate response and mask ischemic changes 2
   • Caffeine blocks adenosine receptors, reducing vasodilator efficacy 1

2. Inappropriate agent selection:

   • Using vasodilators in patients with severe bronchospastic disease
   • Using dobutamine in patients with uncontrolled arrhythmias

3. Incomplete clinical information:

   • Omitting relevant cardiac history or current symptoms
   • Not specifying the exact indication for testing

4. Not accounting for patient-specific factors:

   • Mobility limitations affecting positioning for imaging
   • Claustrophobia that may affect tolerance of imaging procedure

By following this structured approach, you can ensure proper ordering of cardiac chemical stress tests that will yield diagnostically valuable results while maintaining patient safety.