Chronic stable angina myocardial perfusion scintigraphy: Difference between revisions
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''' | '''Editor-In-Chief:''' [[C. Michael Gibson, M.S., M.D.]] [mailto:mgibson@perfuse.org] Phone:617-632-7753; '''Associate Editor(s)-in-Chief:''' {{CZ}}; Smita Kohli, M.D. | ||
'''''Synonyms and keywords:''''' Myocardial perfusion imaging, MPI, myocardial perfusion scan, exercise myocardial perfusion imaging, stress thalium scan, nuclear stress test. | '''''Synonyms and keywords:''''' Myocardial perfusion imaging, MPI, myocardial perfusion scan, exercise myocardial perfusion imaging, stress thalium scan, nuclear stress test. | ||
==Overview== | |||
In patients with baseline [[Chronic stable angina electrocardiography|ECG abnormalities]], myocardial perfusion test can be used to '''localize''' the region of [[ischemia]]. Thallium-201 and technetium-99m are frequently used myocardial perfusion tests. Myocardial uptake of thallium-201 chloride is directly proportional to the regional myocardial blood flow and is dependent on the presence of viable myocardium. The absence of a perfusion defect on thallium scan despite the presence of symptoms indicate excellent prognosis. Contraindications for thallium stress test include the presence of [[arrhythmia]], acute [[myocarditis]], [[aortic stenosis|severe aortic stenosis]] and acute [[MI]] within the past 2 days. | |||
==Myocardial Perfusion Scintigraphy== | ==Myocardial Perfusion Scintigraphy== | ||
Revision as of 02:13, 18 August 2011
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Smita Kohli, M.D.
Synonyms and keywords: Myocardial perfusion imaging, MPI, myocardial perfusion scan, exercise myocardial perfusion imaging, stress thalium scan, nuclear stress test.
Overview
In patients with baseline ECG abnormalities, myocardial perfusion test can be used to localize the region of ischemia. Thallium-201 and technetium-99m are frequently used myocardial perfusion tests. Myocardial uptake of thallium-201 chloride is directly proportional to the regional myocardial blood flow and is dependent on the presence of viable myocardium. The absence of a perfusion defect on thallium scan despite the presence of symptoms indicate excellent prognosis. Contraindications for thallium stress test include the presence of arrhythmia, acute myocarditis, severe aortic stenosis and acute MI within the past 2 days.
Myocardial Perfusion Scintigraphy
- Myocardial perfusion scintigraphy with thallium-201 is frequently employed as a noninvasive test to evaluate abnormalities of myocardial perfusion in patients with established or suspected CAD.
- Myocardial uptake of thallium-201 chloride is proportional to regional myocardial blood flow and is dependent on the presence of viable myocardium.
- During exercise, the magnitude of the increase in blood flow to the non-ischemic myocardial zones is greater than to the zones supplied by stenotic coronary arteries. Owing to this heterogeneous distribution of blood flow, the relative extraction of thallium by non-ischemic myocardium is greater than that by ischemic myocardium.
- During exercise thallium testing, the isotope is administered intravenously during peak exercise, and stress images are obtained immediately after discontinuation of exercise. These images reveal a decreased uptake by the ischemic myocardium, creating a perfusion defect.
- Redistribution images are obtained after 4 hours. Myocardium that was ischemic during stress but that is not ischemic at rest now extracts the isotope. Therefore, the perfusion defects during stress images are not observed in the rest images, and these reversible perfusion defects indicate the presence of viable myocardium.
- If the perfusion defects in stress images persist in the rest images, that is, if the perfusion defects are fixed, the myocardium is usually necrotic or fibrotic.
- A repeat injection of thallium and scanning 24 hours after stress can distinguish severely ischemic area from viable myocardium.
- Thallium images may be planar or tomographic (single photon emission computed tomography=SPECT). The latter are more accurate and are therefore used more frequently to assess the presence and extent of ischemic and infarcted myocardium.
Sensitivity and Specificity of Myocardial Perfusion Scintigraphy:
- In pooled analyses from multiple studies, exercise treadmill thallium myocardium scintigraphy has sensitivity for detecting CAD and specificity for excluding it of about 84% and 88%, respectively. The sensitivity approaches 90% with a quantitative computer-assisted analysis of the images without loss of specificity.
- Considerable experience is required for the performance and interpretation of exercise thallium scintigraphy to achieve these high degrees of specificity and sensitivity.
- Exercise thallium scintigraphy is less likely than exercise electrocardiography to provide false positive test results in women, but it may give false positive test results in patients with hypertrophic, dilated and infiltrative cardiomyopathies.
- Like the exercise ECG, thallium stress scintigraphy is less sensitive in the diagnosis of single vessel disease, particularly of circumflex coronary artery stenosis, than in multi vessel coronary artery disease.
Technetium-99m:
- Technetium-99m, a calcium analog with a higher photon energy and a shorter half life than thallium chloride, can be linked to a variety of agents and used as a marker of myocardial perfusion.
- Technetium-99m-sestamibi is an isonitrile compound that, like thallium, is taken up by the myocardium proportional to blood flow but in contrast to thallium does not undergo redistribution.
- Tomographic images with technetium-99m also allow images to be acquired on the first pass through the ventricle and can be used to assess the left ventricular ejection fraction. However, as a noninvasive, less expensive and readily available test at more centers, echocardiography is usually preferable method for this purpose.
ACC / AHA Guidelines- Nuclear Stress Testing in patients Who Are Able to Exercise (DO NOT EDIT)[1]
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Class I1. Exercise myocardial perfusion imaging or exercise echocardiography in patients with an intermediate pretest probability of CAD who have 1 of the following baseline ECG abnormalities:
2. Exercise myocardial perfusion imaging or exercise echocardiography in patients with prior revascularization (either percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft (CABG). (Level of Evidence: B) 3. Adenosine or dipyridamole myocardial perfusion imaging in patients with an intermediate pretest probability of CAD and 1 of the following baseline ECG abnormalities:
Class IIb1. Exercise myocardial perfusion imaging and exercise echocardiography in patients with a low or high probability of CAD who have 1 of the following baseline ECG abnormalities:
2. Adenosine or dipyridamole myocardial perfusion imaging in patients with a low or high probability of CAD and 1 of the following baseline ECG abnormalities:
3. Exercise myocardial perfusion imaging or exercise echocardiography in patients with an intermediate probability of CAD who have 1 of the following:
4. Exercise myocardial perfusion imaging, exercise echocardiography, adenosine or dipyridamole myocardial perfusion imaging, or dobutamine echocardiography as the initial stress test in a patient with a normal rest ECG who is not taking digoxin. (Level of Evidence: B) 5. Exercise or dobutamine echocardiography in patients with left bundle-branch block. (Level of Evidence: C) |
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See Also
Sources
- TheACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina [2]
- The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina [1]
- The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina [3]
References
- ↑ 1.0 1.1 Gibbons RJ, Chatterjee K, Daley J, et al. ACC/AHA/ACP–ASIM guidelines for the management of patients with chronic stable angina: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Chronic Stable Angina). Circulation. 1999; 99: 2829–2848. PMID 10351980
- ↑ Gibbons RJ, Abrams J, Chatterjee K, Daley J, Deedwania PC, Douglas JS, Ferguson TB Jr, Fihn SD, Fraker TD Jr, Gardin JM, O'Rourke RA, Pasternak RC, Williams SV, Gibbons RJ, Alpert JS, Antman EM, Hiratzka LF, Fuster V, Faxon DP, Gregoratos G, Jacobs AK, Smith SC Jr; American College of Cardiology; American Heart Association Task Force on Practice Guidelines. Committee on the Management of Patients With Chronic Stable Angina. ACC/AHA 2002 guideline update for the management of patients with chronic stable angina--summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Chronic Stable Angina). Circulation. 2003 Jan 7; 107 (1): 149-58. PMID 12515758
- ↑ Fraker TD Jr, Fihn SD, Gibbons RJ, Abrams J, Chatterjee K, Daley J, Deedwania PC, Douglas JS, Ferguson TB Jr, Gardin JM, O'Rourke RA, Williams SV, Smith SC Jr, Jacobs AK, Adams CD, Anderson JL, Buller CE, Creager MA, Ettinger SM, Halperin JL, Hunt SA, Krumholz HM, Kushner FG, Lytle BW, Nishimura R, Page RL, Riegel B, Tarkington LG, Yancy CW; American College of Cardiology; American Heart Association; American College of Cardiology/American Heart Association Task Force on Practice Guidelines Writing Group. 2007 chronic angina focused update of the ACC/AHA 2002 Guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines Writing Group to develop the focused update of the 2002 Guidelines for the management of patients with chronic stable angina. Circulation. 2007 Dec 4; 116 (23): 2762-72. Epub 2007 Nov 12. PMID 17998462