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Title: Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study

Abstract

Thallium imaging of the heart using dipyridamole-induced coronary arteriolar vasodilation has proven to be an effective means of detecting significant coronary stenosis. However, intravenous dipyridamole has not yet been made available for general use. We therefore examined the feasibility of substituting amyl nitrite inhalation as an arteriolar vasodilator prior to thallium imaging. Seventeen patients, all of whom had catheterization-proven coronary stenosis, inhaled amyl nitrite for 2-5 min. Thallium was injected after 45-60 s of inhalation. Completion of inhalation was followed immediately by planar imaging. Of 6 patients who inhaled amyl nitrite for at least 4 min, 5 had moderate or severe image defects on immediate scans which completely resolved on delayed scans. Only 3 of 11 who inhaled amyl nitrite for 2 min or less prior to scanning had similarly positive tests. Overall sensitivity for significant stenosis was 8 of 17 (47%). Inhalation was well tolerated with only one episode of angina and hypotension. We conclude that amyl nitrite inhalation for at least 4 min may offer an effective and readily available alternative to intravenous dipyridamole for vasodilator imaging of the heart.

Authors:
; ; ; ; ;  [1]
  1. (Univ. of Massachusetts School of Medicine, Worcester (USA))
Publication Date:
OSTI Identifier:
5546490
Resource Type:
Journal Article
Resource Relation:
Journal Name: Clinical Cardiology; (USA); Journal Volume: 14:1
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; CARDIOVASCULAR DISEASES; DIAGNOSIS; HEART; IMAGE PROCESSING; INHALATION; NITRITES; PATIENTS; THALLIUM ISOTOPES; VASODILATORS; BODY; CARDIOVASCULAR AGENTS; CARDIOVASCULAR SYSTEM; DISEASES; DRUGS; INTAKE; ISOTOPES; NITROGEN COMPOUNDS; ORGANS; OXYGEN COMPOUNDS; PROCESSING; 550601* - Medicine- Unsealed Radionuclides in Diagnostics

Citation Formats

Rifkin, R.D., Sharma, S.C., Spraragen, S., Claunch, B., Shackford, H., and Patton, R. Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study. United States: N. p., 1991. Web. doi:10.1002/clc.4960140110.
Rifkin, R.D., Sharma, S.C., Spraragen, S., Claunch, B., Shackford, H., & Patton, R. Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study. United States. doi:10.1002/clc.4960140110.
Rifkin, R.D., Sharma, S.C., Spraragen, S., Claunch, B., Shackford, H., and Patton, R. 1991. "Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study". United States. doi:10.1002/clc.4960140110.
@article{osti_5546490,
title = {Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study},
author = {Rifkin, R.D. and Sharma, S.C. and Spraragen, S. and Claunch, B. and Shackford, H. and Patton, R.},
abstractNote = {Thallium imaging of the heart using dipyridamole-induced coronary arteriolar vasodilation has proven to be an effective means of detecting significant coronary stenosis. However, intravenous dipyridamole has not yet been made available for general use. We therefore examined the feasibility of substituting amyl nitrite inhalation as an arteriolar vasodilator prior to thallium imaging. Seventeen patients, all of whom had catheterization-proven coronary stenosis, inhaled amyl nitrite for 2-5 min. Thallium was injected after 45-60 s of inhalation. Completion of inhalation was followed immediately by planar imaging. Of 6 patients who inhaled amyl nitrite for at least 4 min, 5 had moderate or severe image defects on immediate scans which completely resolved on delayed scans. Only 3 of 11 who inhaled amyl nitrite for 2 min or less prior to scanning had similarly positive tests. Overall sensitivity for significant stenosis was 8 of 17 (47%). Inhalation was well tolerated with only one episode of angina and hypotension. We conclude that amyl nitrite inhalation for at least 4 min may offer an effective and readily available alternative to intravenous dipyridamole for vasodilator imaging of the heart.},
doi = {10.1002/clc.4960140110},
journal = {Clinical Cardiology; (USA)},
number = ,
volume = 14:1,
place = {United States},
year = 1991,
month = 1
}
  • The ST segment shift relative to exercise-induced increments in heart rate, the ST/heart rate slope (ST/HR slope), has been proposed as a more accurate ECG criterion for diagnosing significant coronary artery disease (CAD). Its clinical utility, with the use of a standard treadmill protocol, was compared with quantitative stress thallium (TI) and standard treadmill criteria in 64 unselected patients who underwent coronary angiography. The overall diagnostic accuracy of the ST/HR slope was an improvement over TI and conventional ST criteria (81%, 67%, and 69%). For patients failing to reach 85% of their age-predicted maximal heart rate, its diagnostic accuracy wasmore » comparable with TI (77% and 74%). Its sensitivity in patients without prior myocardial infarctions was equivalent to that of thallium (91% and 95%). The ST/HR slope was directly related to the angiographic severity (Gensini score) of CAD in patients without a prior infarction (r = 0.61, p less than 0.001). The ST/HR slope was an improved ECG criterion for diagnosing CAD and compared favorably with TI imaging.« less
  • There is little information concerning the prevalence and clinical correlates of increased pulmonary thallium-201 uptake during dipyridamole thallium-201 stress imaging. Accordingly, the clinical characteristics and quantitative thallium-201 findings were correlated with quantitative lung/heart thallium-201 ratio in 87 patients undergoing dipyridamole thallium-201 stress testing. Nineteen patients (22%) had an elevated ratio (greater than 0.51). These patients were more likely to have had an infarction, to be taking beta blockers, and have a lower rate-pressure product after dipyridamole administration than those with a normal ratio (p less than 0.03). An elevated ratio was associated with a greater likelihood of initial, redistribution andmore » persistent defects, as well as left ventricular cavity dilatation on thallium-201 imaging (p less than 0.05). In addition, the number of myocardial segments demonstrating initial, redistribution and persistent defects was also greater in patients with increased ratios (p less than 0.03). Multivariate analysis demonstrated that the presence of redistribution and left ventricular cavity dilatation were the most significant correlates of lung/heart thallium-201 ratio. It is concluded that the prevalence of increased lung/heart thallium-201 ratio with dipyridamole thallium-201 stress imaging is similar to that seen with exercise stress imaging. As with exercise thallium-201 imaging, increased pulmonary thallium-201 uptake may be a marker of functionally more significant coronary artery disease.« less
  • Detection of coronary artery disease (CAD) in patients with aortic valve stenosis (AS) is clinically difficult. Thallium-201 images were generated in 27 patients with AS during combined intravenous dipyridamole and handgrip test, which induces a marked acute increase in coronary blood flow. Isolated AS was noted in 21 patients and combined AS and aortic regurgitation in 6. Thirteen patients had more than 50% diameter stenosis in 1 or more coronary arteries on angiography. Eleven of them had reversible perfusion defects on post-stress thallium scans (sensitivity 85%). Two patients had thallium defects without angiographic evidence of significant CAD (specificity 86%). Inmore » the other 12 patients with normal coronary angiographic findings, the thallium scans were normal. Two patients had dizziness and hypotension after dipyridamole infusion, which disappeared during the handgrip test; 2 others had chest pain during handgrip. One of them was treated with aminophylline and the other with aminophylline and nitroglycerin. No other adverse effects were reported by the patients and no major complications occurred during stress testing. Thus, thallium imaging during combined intravenous dipyridamole and handgrip test appears to be a promising noninvasive method of revealing CAD in patients with AS.« less
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