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MYOCARIDAL PERFUSION STRESS PROTOCOL

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  • 1. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 DUAL-TRACER GATED MYOCARDIAL SCINTIGRAPHY ** Stress testing in done only with a physician present in the stress lab! Primary Indications: *Diagnosis of coronary disease (CAD) *Risk stratification (preoperative/post infarction/chronic CAD/ after unstable angina) *Evaluation of therapeutic interventions in patients with known CAD (anti-ischemic drug therapy/coronary revascularization) Rationale: Immediately following IV administration, Tl-201 is distributed in myocardium in proportion to regional perfusion. Because Tl-201 is a potassium analog, its distribution at later times (i.e., 1-3 hrs after administration) reflects myocardial membrane function and, thus, myocardial viability. Consequently, Tl-201 is retained by viable myocardium (either normal or ischemic), but is not retained by infracted myocardium. Following IV administration, Tc99m Tetrofosmin or Sestamibi is distributed in proportion to regional myocardial perfusion. Because Tc99m Tetrofosmin or Sestamibi does not clear appreciably from myocardium, images of perfusion can be obtained 60-90 minutes following the administration of this tracer. Initially, under resting conditions, images are obtained following the administration of Tl-201 to assess resting perfusion. Subsequently, images are obtained following the administration of Tc99m Tetrofosmin or Sestamibi at peak stress to assess perfusion during stress. Normal myocardium will exhibit homogenous uptake of both tracers. Myocardium with stress-induced ischemia will exhibit reduced uptake of Tc99m Tetrofosmin or Sestamibi and homogenous or near homogenous uptake of Tl-201. Infarcted myocardium will show reduced uptake of both tracers. Interfering Conditions: Because of the low photon energy of Tl-201 (70 keV), prior studies other radiopharmaceuticals may interfere with thallium scintigraphy, and the potential effect of such prior studies should be discussed with the nuclear medicine physician before Tl-201 is administered. The pharmacologic effects of IV dipyridamole or adenosine are blocked by aminophylline and other methylxanthines (such as caffeine, which is found in coffee, tea, chocolate, and most soft 1
  • 2. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 drinks). Patients taking oral dipyridamole should undergo pharmacologic coronary vasodilatation with IV dipyridamole rather than adenosine, because oral dipyridamole prolongs the pharmacologic effect of adenosine and the combination can have marked side effects. The sensitivity of exercise-stress myocardial perfusion imaging for detection of coronary artery disease (CAD) is reduced in patients under treatment with beta-blocking drugs and some calcium-channel blocking drugs. Sensitivity will be improved if these drugs can be held for approximately 24 hours before the study. Pharmacologic stress is generally preferable to exercise stress in patients with left bundle branch block, because of the lower frequency of false-positive results. Also, pharmacologic stress is generally preferable to exercise stress in patients with pacemakers who are unable to achieve an adequate chronotropic response to exercise. Dobutamine may be preferred to dipyridamole or adenosine in patients with emphysema or asthma. Precautions: Assure intravenous position of the catheter before tracer administration, since subcutaneous extravasation of Tl-201 can lead to significant local radiation exposure (rarely leading to skin sloughing). If a large amount of a Tl-201 dose is extravasated, application of warm compresses to the injection site and elevation of the extremity will enhance absorption and reduce local radiation dose. The nuclear medicine physician should be notified in the event of significant Tl-201 extravasation. Subcutaneous extravasation of a significant portion of an administered dose of Tc99m Tetrofosmin or Tc99m Sestamibi markedly reduces the diagnostic value of the study, since much of the radiopharmaceutical will not reach the myocardium at the point of maximum exercise stress or pharmacologic effect. Radiopharmaceuticals: Tl-201 Thallous chloride and Tc99m Tetrofosmin (Myoview™) or Tc99m Sestamibi (Cardiolite®) Adult Dose: Tl-201: 2.5 mCi for patients weighing less than 180 pounds 3.5 mCi for patients weighing more than 180 pounds or for patients who are to be imaged ≥ 8 hours following Tl-201 injection. Tc99m Tetrofosmin or Sestamibi: 20 mCi for patient’s ≤180 lbs. [A dose of 30 mCi is used for patients weighing ≥ 180 lbs.] 2
  • 3. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 Pediatric Dose: Tl-201: 35 uCi /kg Tc99m Tetrofosmin or Sestamibi: 280 uCi/kg Route of Administration: Intravenous through pre-established, freely infusing cannula. In adults, 22-gauge is the minimum recommended cannula size. Patient Preparation: Patients generally should be fasting for 8-12 hours prior to the test. If Tl-201 is to be injected the night before the study, this should be done at least 2-3 hours after the last meal, and the patient should then be kept fasting after midnight. A minimum fasting interval of 4 hours is recommended when the longer duration of fasting is not possible. Medications that effect cardiac function such as beta- blockers (see above), calcium-channel blockers, digoxin, and nitrates ideally should be discontinued if the goal of the test is to detect coronary artery disease with maximum sensitivity (but this decision is left to the discretion of the patient’s referring physician). Other drugs that diminish the effect of dipyridamole or adenosine (see above) should be discontinued at least 24 hours before the study. Although these drugs may affect the diagnostic accuracy of the study by attenuating the level of exercise stress or pharmacologic effect achieved, they should not otherwise affect the distribution of either tracer in myocardium. Equipment Setup: Gamma camera: SPECT imaging, with gated acquisition for Tc99m Tetrofosmin or Sestamibi if possible, is preferred for both adult and pediatric patients. In patients who are unable to tolerate SPECT, planar imaging should be performed with LFOV camera for studies in adults and SFOV or zoomed-LFOV camera for studies in small children. Collimator: LEHR Energy Windows: Tl-201 (72 keV with a 20% window) (167 keV with a 15%) Tc99m agents (140 keV with a 20 % window) Patient Positioning: SPECT: The patient should be positioned supine, with arm comfortably positioned above the head; the arms should NOT be physically restrained above the head. A hand grip for the patient to hold and/or a wedge pillow placed under knees may be used for patient comfort. The 3
  • 4. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 arm should not be lowered midway through the study (e.g., after the camera passes on one side). It is essential that the patient remain motionless during the entire SPECT acquisition. Planar: The patient will be placed in the supine position for the 35° left anterior oblique (LAO) view and anterior view. the patient will be placed in the right lateral decubitus position with the left arm above the head for the 70° LAO view. Procedure: Tl-201 Rest Study. The patient is injected in the upright position; imaging is begun a minimum of 15 minutes later. To optimize detection of viable myocardium, longer intervals between injection and imaging are preferable and, when possible, inpatients will be injected the night before the study is performed. SPECT imaging should be performed in all patients who can tolerate SPECT. Inpatients unable to tolerate SPECT, a standard set of three 10 minute planar images in 35° LAO, anterior, and 70° LAO projections is to be preformed. Before proceeding to the stress portion of the protocol, the Tl-201 images must be reviewed for patient motion. If significant patient motion has occurred, then the patient’s ability to remain motionless should be reassessed and either repeat SPECT acquisition or standard planar imaging should be performed. Tc99m Tetrofosmin or Sestamibi Study. Once the adequacy of the rest images has been confirmed, this portion of the study can be performed. The same type of image acquisition (SPECT or planar) should be performed as that of the rest study. Whenever possible, gating (8 frames/R-R interval) should be performed. Attach three nuclear medicine computer electrocardiographic leads to the patient. Confirm that the electrocardiographic gating is functioning properly. If there is an arrhythmia, obtain a rhythm strip, if possible, and attach it to the requisition. If not possible, note the presence of an arrhythmia on the requisition. The patient will undergo exercise or pharmacologic stress under the supervision of an Internal Medicine Resident, and Tc99m Tetrofosmin or Sestamibi is injected intravenously at peak exercise or at the time of peak pharmacologic effect. Where exercise is used as the form of stress, the patient should be encouraged to continue exercising for approximately 1 minute after the injection of the radiopharmaceutical. Imaging can be initiated 30 minutes after the administration of the radiopharmaceutical. When pharmacologic stress testing is performed, imaging can be initiated 45-60 minutes after the administration of the radiopharmaceutical. All required information should be entered on the quality control 4
  • 5. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 form (e.g. patient height and weight, body habitus, brassiere size, arm counts). Before the patient leaves the all images should be reviewed for patient motion and the amount of hepatic activity. If significant patient motion has occurred, the patient’s ability to remain motionless should be reassessed and either repeat SPECT acquisition or standard planar imaging should be performed. If excess hepatic activity may be causing an apparent inferior wall perfusion defect, repeat SPECT acquisition should be performed after a delay of an hour or more. View Digital Acquisition Film Display Rest Tl-201 SPECT Study: SPECT Acquisition 64 projection views covering 180° (45° RAO to 135° LPO) 64 x64 word-mode 30 seconds per view Total imaging time-~16 minutes [30 sec/view x 32 views ( with 2 heads)] Images to be displayed along with corresponding stress images Rest Tl-201 SPECT Study: SPECT Reconstruction No attenuation correction Rest Tl-201 Planar Study: (3 views) 35° LAO and Anterior views with patient supine 70° LAO view with patient in right lateral decubitus position 256 x 256 word-mode 10 minute images Images to be displayed along with corresponding stress images Stress Tc99m Tetrofosmin or Tc99m Sestamibi SPECT Study: SPECT Acquisition 64 projection views covering 180° (45° RAO to 135° LPO) 64 x64 word-mode 30 seconds per view Total imaging time-~16 minutes [30 sec/view x 32 views ( with 2 heads)] 8 Frames/ R-R interval, whenever possible Image of stress-rest slices and images of ED, ES, motion, and thickening bull’s-eyes. Stress Tc99m Tetrofosmin or Tc99m Sestamibi SPECT Study Reconstruction No attenuation correction 5
  • 6. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 Stress Tc99m Tetrofosmin or Tc99m Sestamibi Planar Study: (3 views) 35° LAO and Anterior views with patient supine 70° LAO view with patient in right lateral decubitus position 256 x 256 word-mode 8 minute images Images to be displayed along with corresponding rest images Dual-Tracer Myocardial Imaging Time RESTING STUDY Tl-201 Resting Images: Please Image at 15 minutes post injection Exercise Study Tc99m Tetrofosmin (Myoview) Exercise (Bruce) Stress Test: Minimal delayed imaging time between 10 to 15 minutes. Tc99m Tetrofosmin (Myoview) Pharmacologic (Chemical) Stress Test: Please do delayed images at 60 minutes No later than 90 minutes post injection. 6
  • 7. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 PHARMACOLOGIC VASODILATORY STRESS ADENOSINE- Mechanism of action. Direct coronary arteriolar vasodilatation that induces an attenuated hyperemic response in myocardial regions supplied by a disease coronary artery. Depending on the severity of coronary artery. Depending on the severity of coronary stenosis and limitations in coronary flow reserve, adenosine will induce relative heterogeneity in coronary blood flow. The initial uptake of Tc99m MIBI and Tl-201 is flow dependent and unequal distribution of radioisotope into the myocardium will be identified as a perfusion defect. DOSE: 140 ug/kg/min over a 6 minute period INDICATIONS: *Inability to perform adequate exercise or in patients with left bundle-branch or in patients taking medications that would reduce the sensitivity of the test. *Diagnosis and evaluation of coronary artery disease *Risk stratification particularly in the early post infarction setting (≥ 48 hours) *Evaluation of therapeutic benefits after angioplasty or coronary artery bypass surgery HEMODYNAMIC EFFECTS: *A post-related modest increase in heart rate *Decrease in both systolic and diastolic blood pressure ABSOLUTE CONTRAINDICATIONS: *Ongoing wheezing *Greater than first-degree AV block without pacemaker *Hypotension (systolic blood pressure < 90 mm Hg) *Recent (<24 hrs) use of dipyridamole or xanthenes (aminophylline, caffeine). Pentoxiphylline (Trental) may be an exception. RELATIVE CONTRAINDICATIONS: *Remote history reactive airway disease (asthma, COPD) *Sick sinus syndrome *Severe sinus (< 40/min) bradycardia PROCEDURE: 1. An infusion pump is necessary for the administration of adenosine. 2. A dual-ported connector is used for injecting the radiopharmaceutical. 3. Electrocardiographic monitoring and blood pressure determinations are performed as with exercise stress. 4. Adenosine infusion rate at 140 ug/kg/min for 3 minutes followed by injection of radiopharmaceutical. The infusion is then continued for 3 7
  • 8. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 additional minutes. EARLY TERMINATION OF ADENOSINE INFUSION *Severe hypotension (blood pressure <90 mm Hg) *Development of Symptomatic, persistent second-degree or complete heart block *Wheezing *Severe chest pain associated electrocardiographic ischemic changes (≥ 2 mm ST segment depression) SIDE EFFECTS OF ADENOSINE- Occur in approximately 80% of patients. The most common are flushing (35%), chest pain (34%), dyspnea (19%), electrocardiographic ST segment depression (13%), dizziness (7%), nausea (5%), and hypotension (3%). *Fatal or nonfatal myocardial infarctions have been rarely reported with adenosine. *Due to the exceedingly short half-life of adenosine (< 2 seconds), most side effects resolve within 1 to 2 minutes of terminating the adenosine infusion. *If side effects persist after stopping the infusion of adenosine, aminophylline can be administered. DOBUTAMINE-Unlike the coronary vasodilators, Dobutamine is a positive isotropic, Through stimulation of beta-1 receptors, produces an increase in heart muscle contraction and resulting increase in oxygen demand produces a stressed state. Doses of Dobutamine > 20 ug/kg/min also have chronotropic effects on the heart. High doses of Dobutamine (40 ug/kg/min) produce an increase in heart rate from 70 ± 16 to 121 ± 23 bpm. DOSE: Dobutamine is infused incrementally starting at a dose of 5 ug/kg/min, which is increased at 3 minute intervals to 10, 20, 30, and up to 40 ug/kg/min. INDICATIONS: *Dobutamine is a secondary pharmacologic stressor that is used in patients who cannot undergo exercise stress, but yet have contraindications to pharmacologic vasodilator stressors. CONTRAINDICATIONS: *Recent (< 1 week) myocardial infarction * Unstable angina *Hemodynamically significant left ventricular outflow tract obstruction *Critical aortic stenosis *Atrial tachyarrhythmia with uncontrolled ventricular response 8
  • 9. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 *Ventricular tachycardia *Uncontrolled hypertension *Patients with aortic dissections or large aortic aneurysm PROCEDURE: *Infusion pump required for Dobutamine administration *Electrocardiographic monitoring blood pressure determinations as with other pharmacologic stressors *Dobutamine administered starting at a dose of 5 ug/kg/min and increasing at 3 minute intervals up to 40 ug/kg/min, with injection of radiopharmaceutical at 1 minute into the highest Dobutamine dose; Dobutamine infusion is maintained for 2 minutes after the tracer injection. EARLY TERMINATION OF DOBUTAMINE: Similar indications as those used for exercise stress. Termination for ventricular tachycardia or ST segment elevation is more likely than with other stressors. SIDE EFFECTS: *Are reported in some 75 % of patients *The most common side effects are chest pain (31 %), palpitations (29 %), headache (14%), flushing (14%), dyspnea (14%), and paresthesia (12 %). Ischemic ST segment occurs in approximately 50 % of patients during Dobutamine infusion. *Severe side effects may require IV administration of short-acting beta-blocker (Esmolol). LEXISCAN™ (Regadenoson) Injection- is a pharmacologic stress agent indicated for radionuclide myocardial perfusion imaging in patients unable to undergo adequate exercise stress. DOSE: The recommended dose of Lexiscan is 5 mL (0.4 mg regadenoson) by rapid intravenous injection; followed by saline flush and radiopharmaceutical. INDICATIONS: Lexiscan is indicated for use in pharmacologic stress MPI, with no specific requirements regarding the tracer or imaging protocol used. Pharmacologic stress is conducted in patients who are unable to exercise adequately due to poor physical conditioning, poor motivation, or diseases or conditions that limit physical exertion or activity (e.g., lower limb amputation, arthritis, etc). 9
  • 10. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 HEMODYNAMIC EFFECTS: The majority of patients had an increase in heart rate and a decrease in blood pressure within 45 minutes after the administration of Lexiscan. Heart rate: > 100 bpm (22%), increase > 40 bpm (5%); Systolic Blood Pressure: < 90 mm Hg (2%), decrease > 35 mm Hg (7%) Diastolic Blood pressure: < 50 mm Hg (2%), decrease > 25 mm Hg (4%). ABSOLUTE CONTRAINDICATIONS: Do not administer Lexiscan to patients with second or third degree AV block, or sinus node dysfunction unless these patients have a functioning artifical pacemaker. WARNINGS AND PRECAUTIONS: *Myocardial Ischemia. Fatal cardiac arrest, life threatening ventricular arrhythmias, and myocardial infarction may result from the ischemia induced by pharmacologic stress agents. Cardiac resuscitation equipment and trained staff should be available before administering Lexiscan. *Sinoatrial and Atrioventricular Nodal Block. In clinical trials first degree AV block (PR prolongation > 220 msec) developed in 3% of patients within 2 hours of Lexiscan administration; transient second degree AV block with one dropped beat was observed in one patient receiving Lexiscan. All episodes of AV block were asymptomatic and did not require intervention. *Hypotension. Decreased systolic blood pressure (> 35 mm Hg) was observed in 7 % of patients and decreased diastolic blood pressure (> 25 mmHg) was observed in 4 % of patients within 45 minutes of Lexiscan administration. The risk of serious hypotension may be higher in patients with autonomic dysfunction, hypovolemia, left main coronary artery stenosis, stenotic valvular heart disease, pericarditis or pericardial effusions, or stenotic carotid artery disease with cerebrovascular insufficiency. *Bronchoconstriction. Adenosine receptor agonists may cause bronchoconstriction and respiratory compromise. For patients with known or suspected bronchoconstrictive disease, chronic obstructive pulmonary disease (COPD) or asthma, appropriate bronchodilator therapy and resuscitative measures should be available prior to Lexiscan administration. PROCEDURE: 1. Administer Lexiscan as a rapid (approximately 10 seconds) injection into a peripheral vein using a 22 gauge or larger catheter or needle. 2. Administer a 5 mL saline flush immediately after the injection of Lexiscan. 3. Administer the radionuclide myocardial perfusion imaging agent 10-20 seconds after the saline flush. The radionuclide may be injected directly into the same catheter as Lexiscan. 10
  • 11. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 SIDE EFFECTS: *Are reported in some 80 % of patients *The most common side effects are dyspnea (28%), headache (26%), flushing (16%), chest discomfort (13%), angina pectoris or ST segment depression (12%), dizziness (8%), chest pain (7%), nausea (6%), abdominal discomfort (5%), dysgeusia (5%), and feeling hot (5%). Reviewed and Revised: 8/19/2008 11
  • 12. Nuclear Medicine Department Policy and Procedure Manual Myocardial Perfusion Stress Protocol Dual-Tracer Proc. 18.8.5.1 12

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