MYOCARDIAL PERFUSION STUDY -STRESS TESTING
The different stress testing protocols available for myocardial perfusion study are:
� Thallium stress testing (with treadmill).
� Pharmacological thallium stress study with Adenosine, Persantine (Dipyridamole) or Dobutamine.
� Dual stress test (thallium rest and Cardiolite or Myoview stress with treadmill).
� Pharmacological dual stress test (Adenosine, Persantine or Dobutamine).
� 2-day exercise or pharmacological stress testing with Cardiolite or Myoview.
� 1-day exercise or pharmacological stress testing with Cardiolite or Myoview.
MYOCARDIAL PERFUSION STUDY - TREADMILL STRESS TESTING
1. After establishing intravenous access and setting the patient up for the treadmill, the patients resting blood pressure and ECG are taken.
2. Perform Bruce protocol for stress testing trying to achieve at least 85% of maximum predicted heart rate before injecting Tl-201, Cardiolite or Myoview.
3. Inject patient 1 minute before he needs to stop the treadmill stress with Tl-201 or Myoview and at least 2 minute before patient stop treadmill with Cardiolite.
4. Thallium stress imaging should be started within 10 minutes of injection while one can wait 20 minutes or longer for imaging with Myoview or Cardiolite.
Potential pitfalls:
1. If patient does not achieve at least 85% of the heart rate during myocardial treadmill stress perfusion study, the images are not as diagnostic as when a patient achieves 85% or higher heart rate.
2. Beta blocking medication should be stopped 24 to 48 hours prior to perfusion stress testing unless the physician asks them to take it. Beta blocking medication results in less of a heart rate response during treadmill stress causing a nondiagnostic result.
3. Stress at least 2 minutes post Cardiolite injection as extraction of cardiolite takes longer to be taken up by myocardium than thallium or Myoview (1 minute).
MYOCARDIAL PERFUSION STUDY - ADENOSINE STRESS (6 Minute Protocol)
1. Patient should be at least 6-8 hours NPO.
2. Patient should be off theophylline and beta blocking medications for at least 24 hours.
3. Patient should be instructed not to drink any caffeinated drinks or beverages at least 24 hours prior to the study (cola, coffee, chocolate, tea including decaffeinated coffee, medication containing caffeine and even chewing gum which may contain caffeine).
Procedure:
After the informed consent and discussing risk and benefit of Adenosine stress test, the test can perform two different ways: patient who can able to walk slowly and patient who can not walk or patient with LBBB, pacemaker or defibrillator.
1. Infuse adenosine with infusion pump for 6 minutes with rate of 140mcg/kg/min (Dose = .84mg/kg).
2. Walk patient on treadmill, who can able to walk during 6-minute infusion. Older patients and patient with limited walking capacity can walk 1 mile/hour or 0.8 mile/hour on treadmill without grade during adenosine infusion.
3. Walk patient on treadmill, who can able to do Bruce protocol on 1st stage and some times on 2nd stage during 6 minute adenosine infusion.
4. Patient who cannot walk will be lying on a gurney with 6 minute of adenosine infusion. Patients can squeeze handgrips for 6 minutes infusion. Do not walk or use handgrips on patients with LBBB, pacemaker or defibrillator.
5. Monitor blood pressure and heart rate every minute.
6. Inject patient with Tl-201, Cardiolite or Myoview at 3 minute into the infusion.
7. Monitor patient for 8 minutes during recovery or until resolutions of symptoms and EKG returns to baseline.
8. Thallium stress imaging should be performed right after the recovery. Myoview imaging can be stated within 30 minutes while Cardiolite about 45 minutes to an hour for patients who do not walk or earlier if the patient has combined Adenosine infusion with some treadmill exercise.
Complications:
Symptoms of headache, flushing, jaw pain, nausea, vomiting, dizziness, hypotension or chest pain are expected during adenosine infusion. In rare instances respiratory arrest, myocardial infarct or 3rd degree AV block have been known to occur. At the physician's discretion the test can be stopped early if symptoms are intolerable.
Walking patient on treadmill during Adenosine infusion may lessen some of the symptoms and results in less hypotension and AV Block. It also helps with AV block on patients with prolonged PR interval. Also image characteristics of heart to background ratio will be better on patients walked during adenosine infusion.
ADENOSINE STRESS (4 Minute Protocol)
1. Patient should be at least 6-8 hours NPO.
2. Patient should be off theophylline and beta blocking medications for at least 24 hours.
3. Patient should be instructed not to drink any caffeinated drinks or beverages at least 24 hours prior to the study (cola, coffee, chocolate, tea including decaffeinated coffee, medication containing caffeine and even chewing gum which may contain caffeine).
Procedure:
After the informed consent and discussing risk and benefit of Adenosine stress test, the test can perform two different ways: patient who can able to walk slowly and patient who can not walk or patient with LBBB, pacemaker or defibrillator.
1. Infuse adenosine with infusion pump for 4 minutes with rate of 140mcg/kg/min (Dose = .56mg/kg).
2. Walk patient on treadmill, who can able to walk during 4-minute infusion. Older patients and patient with limited walking capacity can walk 1 mile/hour or 0.8 mile/hour on treadmill without grade during adenosine infusion.
3. Walk patient on treadmill, who can able to do Bruce protocol on 1st stage and some times on 2nd stage during 4 minute adenosine infusion.
4. Patient who cannot walk will be lying on a gurney with 4 minute of adenosine infusion. Patients can squeeze handgrips for 4 minutes infusion. Do not walk or use handgrips on patients with LBBB, pacemaker or defibrillator.
5. Monitor blood pressure and heart rate every minute.
6. Inject patient with Tl-201, Cardiolite or Myoview at 2 minute into the infusion.
7. Monitor patient for 6-8 minutes during recovery or until resolutions of symptoms and EKG returns to baseline.
8. Thallium stress imaging should be performed right after the recovery. Myoview imaging can be stated within 30 minutes while Cardiolite about 45 minutes to an hour for patients who do not walk or earlier if the patient has combined Adenosine infusion with some treadmill exercise.
Complications:
Symptoms of headache, flushing, jaw pain, nausea, vomiting, dizziness, hypotension or chest pain are expected during adenosine infusion. In rare instances respiratory arrest, myocardial infarct or 3rd degree AV block have been known to occur. At the physician's discretion the test can be stopped early if symptoms are intolerable.
Walking patient on treadmill during Adenosine infusion may lessen some of the symptoms and results in less hypotension and AV Block. It also helps with AV block on patients with prolonged PR interval. Also image characteristics of heart to background ratio will be better on patients walked during adenosine infusion.
* 1-minute 50 mcg/kg/min * 2-minute 75 mcg/kg/min * 3-minute 100 mcg/kg/min * 4-minute 140 mcg/kg/min * 5-minute 140 mcg/kg/min * 6-minute 140 mcg/kg/min * 7-minute 140 mcg/kg/min
Inject Tl-201, Cardiolite or Myoview at minute 5. The test can be stopped any time at physician's discretion.
Pitfalls of Adenosine Protocol:
1. If the patient had coffee, a caffeinated drink or medication like theophylline, these may affect the physiologic effect of adenosine affecting the inconclusive result.
2. Patient with severe asthma, COPD or emphysema cannot able to go through adenosine testing as it may result in brocheospasm. The 7 minute RAMP protocol may be considered in patients with mild pulmonary disease.
3. Hypotensive response to adenosine and 1st and 2nd degree AV block requires further recovery time or medical intervention.
MYOCARDIAL PERFUSION STUDY-DIPYRIDAMOLE STRESS
1. Patient should be at least 6-8 hours NPO.
2. Patient should be off theophylline medications for at least 24 hours.
3. Patient should be instructed not to drink any caffeinated drinks or beverages at least 24 hours prior to the study (cola, coffee, chocolate, tea including decaffeinated coffee, medication containing caffeine and even chewing gum which may contain caffeine).
Procedure:
After the informed consent and baseline ECG and blood pressure, Persantine stress testing is done as:
1. Dipyridamole (.56mg/kg) is diluted to 40 cc with normal saline and infuses 10cc/minute over a 4-minute interval through infusion pump.
2. Physician must be present throughout the infusion and immediate post infusion period.
3. At 4-minute post Persantine infusion (8-minutes into the test), Tl-201, cardiolite or myoview injected through the IV, followed by saline flush.
4. Patient should be monitor 4 more minutes or until vital signs return to baseline.
5. If patient able to walk or do low-level exercise should be walked for 4-minutes after Persantine infusion.
Complications & pitfalls:
Symptoms of headache, jaw pain, nausea, vomiting, dizziness, hypotension or chest pain are expected during Persantine infusion. In rare instances respiratory arrest, myocardial infarct and even death have been known to occur.
If the patient develops significant symptoms, after Tl-201, Cardiolite or Myoview injected, inject 75-100 mg aminophylline through IV. If significant symptoms develop prior to isotope injection, inject Tl-201, Cardiolite or Myoview immediately, and in one minute inject the aminophilline. Up to 300mg of aminophylline may be administered as a bolus at the discretion of the physician. An aminophylline drip can be started if symptoms warrant it. In patients who require aminophylline, continue to monitor blood pressure and clinical status until minute 30 of the study. This can be accomplished during Tl-201 imaging. This is particularly important since the effects of aminophylline may wear off faster than the effects of Dipyridamole. (T � of dipyridamole =30 minutes, T � of aminophylline =15 minutes). Other pharmaceuticals, such as nitroglycerin, lidocaine etc can be given in conjunction with aminophilline if needed.
MYOCARDIAL PERFUSION STUDY-DOBUTAMINE STRESS
1. Patient should be at least 6-8 hours NPO.
2. Patient should be off beta blocking medications for at least 24 hours.
Contraindications:
1. Resting SBP>180, DBP>120.
2. History of ventricular tachycardia or rapid atrial fibrillation.
3. MI< 3 days.
4. Uncontrolled Atrial Fibrillation.
5. Aortic Stenosis.
Protocol:
1. Patient should be at least 6-8 hours NPO.
2. All beta blocker/adrenogenic therapy to be withheld 24-48 hrs prior to the test.
3. Withdraw 10 ml of dobutamine (125 mg) and add 50 cc of D5W solution in 60 cc syringe (2.08 mg/ml) and put it in dobutamine infusion pump. Start infusion pump according to following protocol:
10 mcg/kg/min x 3 minutes 20 mcg/kg/min x 3 minutes 30 mcg/kg/min x 3 minutes 40 mcg/kg/min x 3 minutes
4. The incremental increase in dobutamine infusion will be discontinued at any time during development of any of the following or at physician's discretion.
a) Frequent or complex ventricular ectopy. b) SBP > 240 or DBP > 130. c) Drop in SBP > 20 mg Hg. d) Moderate or severe chest pain. e) Significant dyspnea. f) ST segment depression > 3mm.
5. Inject Tl-2101, Cardiolite or Myoview one minute into 40 mcg/kg/min has been obtained. Allow the infusion for 2 more minutes unless waved by the physician.
6. At the physician discretion, 50 mcg/kg/minute dose be infused if the heart response is not enough or atropine may be given by physician request. Inject isotope 2 minutes before stopping the infusion.
7. Chart patient blood pressure, heart rate, ST segment changes and patient symptoms every 2 minutes while infusion is proceeding and continue until at least 8-20 minutes after discontinuing dobutamine infusion or longer if needed.
8. Start Tl-201 imaging 8 minutes after infusion, and later with Cardiolite or Myoview imaging.
Contraindications and pitfalls:
1. Most side effects abate within 2-5 minutes of infusion termination, which include chest pain, dyspnea, ventricular and supraventricular ectopy, hypotension, hypertension, ST segment depression, headache and nausea.
2. Medications and crash cart in near vicinity. Verapamil 10 mg/4 ml vial x 2 Lidocaine 100 mg IV Nitroglycerine 1/150 SL pills x 1 bottle Adenosine 2 vial Crash cart with ambu bag, O2 canister and suction equipment.
3. Longer patient recovery required especially when atropine is given.
4. Image characteristics with Dobutamine stress are worse than other types of stress.