What is the traditional order for a chemical cardiac stress test?

How to Write a Traditional Order for Chemical Cardiac Stress Test

A complete chemical cardiac stress test order must specify the pharmacological agent (vasodilator or inotropic), imaging modality, patient preparation requirements, monitoring parameters, and emergency reversal agents available.

Essential Order Components

Patient Demographics and Clinical Information

• Include patient name, date of birth, medical record number, and weight (required for weight-based dosing) 1
• Document clinical indication such as chest pain characteristics, dyspnea, suspected angina equivalent, or preoperative risk assessment 1
• Specify pre-test probability of coronary artery disease (low, intermediate, or high risk) 1
• List relevant cardiac history including prior myocardial infarction, percutaneous coronary intervention, coronary artery bypass grafting, heart failure, or arrhythmias 1

Pharmacological Agent Selection

Choose vasodilator stress (regadenoson, adenosine, or dipyridamole) for most patients, reserving dobutamine for those with contraindications to vasodilators or when valve assessment is needed 2, 3.

For Vasodilator Stress:

• Regadenoson (preferred): 0.4 mg IV bolus over 10 seconds, followed immediately by 5 mL saline flush 4
• Adenosine: 140 μg/kg/min IV infusion over 4-6 minutes 2, 1
• Dipyridamole: 0.84 mg/kg IV infusion over 6-10 minutes 1

For Inotropic Stress:

• Dobutamine: Start at 5-10 μg/kg/min IV, increase by 5-10 μg/kg/min every 3 minutes to maximum 40-50 μg/kg/min 2, 1, 5
• Atropine augmentation: 0.01 mg/kg up to 0.25 mg aliquots every 1-2 minutes (maximum 1 mg total) if target heart rate not achieved with dobutamine alone 2, 1

Imaging Modality Specification

Specify whether nuclear perfusion imaging (SPECT or PET) or stress echocardiography will be performed 2.

For Nuclear Myocardial Perfusion Imaging:

• Document radiopharmaceutical choice (Tc-99m sestamibi, Tc-99m tetrofosmin, or Tl-201) and dosage 2
• Specify rest and stress image acquisition timing (typically stress images 60-90 minutes post-injection) 1
• Indicate if SPECT/CT with attenuation correction will be used 2

For Stress Echocardiography:

• Specify baseline, low-dose, peak stress, and recovery image acquisition 1
• Document assessment parameters: wall motion, valvular function, hemodynamic measurements 1

Patient Preparation Requirements

Critical preparation instructions must be documented to avoid test failure or adverse events 1, 3.

• For vasodilator stress: No caffeine-containing products for 12-24 hours prior (coffee, tea, chocolate, soft drinks) 1, 6
• For vasodilator stress: Hold theophylline/aminophylline for 24 hours, dipyridamole for 48 hours 6
• For all stress tests: Continue beta-blockers and other cardiac medications unless specifically contraindicated 2
• NPO for 4 hours prior to test (light meal acceptable for diabetics) 2

Monitoring Requirements During Test

Continuous monitoring is mandatory throughout the procedure and recovery period 1.

• Continuous 12-lead ECG monitoring from baseline through recovery 2, 1
• Blood pressure measurement at baseline, each stress stage, peak stress, and every 2-3 minutes during recovery 2, 1
• Heart rate monitoring continuously 2, 1
• Oxygen saturation monitoring if clinically indicated (pulmonary disease, heart failure) 1
• Clinical symptom assessment throughout: chest pain, dyspnea, dizziness, nausea 2, 1

Test Termination Criteria

Specify clear endpoints for test completion or early termination 1, 3.

Target Endpoints:

• Achievement of 85% maximum predicted heart rate (220 - age) for dobutamine stress 2
• Completion of full vasodilator infusion protocol 2
• Adequate image acquisition completed 1

Mandatory Termination Criteria:

• Significant ST-segment depression (≥2 mm) or elevation (≥1 mm) 1, 3
• Moderate to severe angina or intolerable symptoms 2, 1
• Systolic blood pressure drop >20 mmHg from baseline or severe hypertension (>200/110 mmHg) 2, 3
• Complex ventricular arrhythmias or sustained supraventricular tachycardia 2, 3
• High-grade atrioventricular block (second or third degree) 2, 3
• Patient request to stop 2

Emergency Medications and Reversal Agents

Emergency medications must be immediately available at bedside before starting the test 1.

For Dobutamine Stress:

• Esmolol: 0.5 mg/kg IV bolus (use 10 mg/mL dilution, not 250 mg/mL) for reversal of dobutamine effects 2, 1
• Alternative: Metoprolol 5 mg IV 2

For Vasodilator Stress:

• Aminophylline: 50-250 mg IV over 30-60 seconds for reversal of adenosine/dipyridamole effects 1, 6
• Note: Aminophylline typically not needed for regadenoson due to ultra-short half-life 4

Standard Emergency Medications:

• Nitroglycerin sublingual or IV 2
• Atropine for symptomatic bradycardia 2
• Full advanced cardiac life support medications and equipment 2

Agent-Specific Contraindications to Document

Absolute Contraindications to Vasodilators:

• Active bronchospasm or severe reactive airway disease with recent wheezing 2, 3, 6
• Second or third-degree atrioventricular block without pacemaker 2, 3
• Sick sinus syndrome without pacemaker 2
• Systolic blood pressure <90 mmHg 2
• Recent use of dipyridamole-containing medications 6

Absolute Contraindications to Dobutamine:

• Unstable angina or acute coronary syndrome 3
• Recent myocardial infarction (<48 hours) 3
• Severe symptomatic aortic stenosis 3
• Uncontrolled hypertension (≥200/110 mmHg) 3
• Uncontrolled atrial fibrillation or flutter 2
• Known severe left main coronary stenosis 2

Common Pitfalls to Avoid

Inadequate patient preparation is the most common cause of non-diagnostic studies 1.

• Failure to document caffeine abstinence for vasodilator stress results in blunted hyperemic response and false-negative studies 1, 6
• Not holding theophylline/aminophylline negates vasodilator effects entirely 6
• Using vasodilators in patients with active bronchospasm can precipitate severe bronchospasm requiring intubation 3, 6
• Insufficient monitoring during recovery period when most adverse events occur 2
• Not having reversal agents immediately available at bedside before starting infusion 1
• Inadequate documentation of baseline ECG abnormalities (left bundle branch block, ST depression) that affect interpretation 2

Sample Order Format

Order: Chemical Cardiac Stress Test

• Agent: Regadenoson 0.4 mg IV bolus OR Dobutamine IV infusion protocol (specify)
• Imaging: SPECT myocardial perfusion imaging with Tc-99m sestamibi (specify dose)
• Indication: [Chest pain, preoperative risk assessment, etc.]
• Patient preparation: NPO 4 hours, no caffeine 24 hours (if vasodilator)
• Monitoring: Continuous 12-lead ECG, BP every stage, pulse oximetry
• Emergency medications at bedside: Aminophylline 250 mg (if vasodilator) OR Esmolol 100 mg (if dobutamine), nitroglycerin, atropine, full ACLS cart
• Physician present: [Name] with ACLS certification current 2