Clinical and physiologic evidence indicates that maximal coronary vasodilation is not achieved in a large number of patients with use of the standard dose of dipyridamole (0.56 mg/kg body weight over 4 min). The feasibility, safety and accuracy of technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Sestamibi) scintigraphy associated with intravenous high dose dipyridamole (0.56 mg/kg over 4 min followed 4 min later by an additional 0.28 mg/kg over 2 min) were evaluated in a multicenter study. Planar myocardial perfusion images were obtained at rest and after dipyridamole in 101 patients with effort chest pain and no prior myocardial infarction. High dose dipyridamole (62 patients) was used when typical chest pain or electrocardiographic (ECG) signs of ischemia, or both, did not occur during or after the standard dose (39 patients). With high dose dipyridamole, 34 patients had pain (18 patients) or ECG signs of ischemia (ST depression greater than or equal to 2 mm) (8 patients), or both (8 patients), whereas the other 28 patients had Sestamibi injection in the absence of symptoms or ECG changes. All patients underwent coronary angiography: 81 had significant coronary artery disease (greater than or equal to 50% reduction of lumen diameter) (affecting one vessel in 38, two vessels in 19 and three vessels in 24 patients) and 20 patients had normal coronary arteries. The overall sensitivity, specificity and predictive accuracy of Sestamibi scintigraphy were 81%, 90% and 83%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
The diagnostic contribution of double-radiocompound renography was tested by applying discriminant analysis to the data obtained in one group of normal subjects and in some groups of selected pathological cases which included glomerulonephritis, pyelonephritis, and hypertension. The results obtained confirm the reliability of the test and give evidence of its usefulness in diagnostic clinical work.
The emptying sequence of ventricular blood pool was studied by scintigraphic regional phase mapping
in 10 patients with monomorphic and sustained ventricular tachycardia (VT) and compared to an electrophysiological
study in order to assess the scintigraphic accuracy for the noninvasive localization of abnormal site of activation.
All patients underwent both phase imaging and electrical mapping studies. There were 6 coronary artery disease
patients, 3 patients with arrhythmogenic right ventricular disease and 1 patient with dilatative cardiomyopathy.
Phase image studies were performed by first harmonic Fourier analysis of radionuclide angiography either during
sinus rhythm or during spontaneous or catheter-induced VT. Eleven morphologically distinct VTs with a heart rate
ranging from 145 to 260 beats min^-1 (mean 173 ± 32 beats min^-1) were imaged. Endocardial catheter mapping was
accomplished in 9 different VT morphologies. Three patients also had epicardial intraoperative mapping. The site of
origin of VT by a scintigraphic method was defined as the area of earliest regional contraction on the biventricular
scintigram. By separating the right ventricle into 5 segments and the left ventricle into 7 segments, with multiple view
cardiac imaging, a close correspondence between the site of origin determined by electrophysiological study and the
region of earliest emptying of radioactivity was observed in 7 of 9 (77%) VTs. In 2 patients the extension of regional
akinesia during VT prevented us from an accurate mapping of the regional time sequence of contraction. Scintigraphic
phase mapping has inherent limitations due to wall motion dependency and relatively low resolution power
but it is feasible in selected patients with monomorphic, inducible and long-sustained VT in whom adequate time for
data collection is provided. In this subset of patients the site of origin of VT could be localized on a 'segmental' basis
with close correspondence to electrophysiological mapping studies.
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