Takahisa Taguchi

Exercise testing and thallium-201 emission computed tomography in patients with intraventricular conduction disturbances

The specificity of exercise thallium-201 emission computed tomography for coronary artery disease was assessed in patients with intraventricular conduction disturbances. Eighty-seven patients were studied: 33 with right bundle branch block (RBBB), 11 with RBBB and left-axis deviation, 11 with left (L)BBB, 12 on right ventricular pacing, and 20 with Wolff-Parkinson-White (WPW) syndrome. A control group of 349 consecutive patients with normal intraventricular conduction was also examined. The specificity of diagnosis of coronary artery disease in patients with LBBB (30%), right ventricular pacing (44%) or RBBB plus left-axis deviation (50%) was significantly lower than in patients with normal intraventricular conduction (94%; p less than 0.01). In contrast, there was no significant difference between specificity in patients with RBBB (86%) or WPW syndrome (90%) and patients with normal intraventricular conduction. Perfusion defects were found in the anterior, septal and inferior segments in patients with LBBB, and in the septal and inferior segments in patients with RBBB plus left-axis deviation despite the absence of coronary stenosis. Furthermore, diffuse slow washout was seen more often in patients with WPW syndrome (35%) than in controls who had normal intraventricular conduction (11%; p less than 0.05), despite a good exercise performance in the former group. This study suggests that there is an increased incidence of abnormal perfusion and clearance during exercise thallium-201 emission computed tomography in patients with intraventricular conduction disturbances.

Clinical significance of plasminogen activator inhibitor activity in patients with exercise-induced ischemia

To assess the fibrinolytic system in patients with exercise-induced ischemia and its relation to ischemia and severity of coronary artery disease (CAD), 47 patients with CAD confirmed by results of coronary angiography underwent symptom-limited multistage exercise thallium-201 emission computed tomography. All patients with CAD had exercise-induced ischemia as assessed from thallium-201 images. Pre- and peak exercise blood samples from each patient and preexercise blood samples from control subjects were assayed for several fibrinolytic components and were also assayed for plasma adrenaline. The extent of ischemia was defined as delta visual uptake score (total visual uptake score in delayed images minus total visual uptake score in initial images) and the severity of CAD as the number of diseased vessels. In the basal condition, plasminogen activator inhibitor (PAI) activity was significantly higher in patients with exercise-induced ischemia as compared to control subjects (p less than 0.01), although there were no significant differences in other fibrinolytic variables between the two groups. Moreover, PAI activity in the basal condition displayed a significantly positive correlation with the extent of ischemia (r = 0.47, p less than 0.01). Patients with exercise-induced ischemia were divided into two groups (24 with single-vessel disease and 23 with multivessel disease). There were no significant differences in coronary risk factors, hemodynamics, or plasma adrenaline levels during exercise between single-vessel and multivessel disease except that delta visual uptake score was significantly higher in multivessel disease (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise-induced silent myocardial ischemia: Evaluation by thallium-201 emission computed tomography

Factors associated with silent myocardial ischemia (SMI) during exercise testing were studied by means of thallium-201 emission computed tomography (ECT) in 471 patients. Coronary angiography was done in 290, of whom 167 were found to have significant coronary artery disease (CAD). Exercise-induced ischemia and its severity were defined with ECT. During exercise 108 (62%) of 173 patients with ischemia and 57 (50%) of 115 with ischemia and angiographically documented CAD had no chest pain. One third of the patients showed an inconsistency between scintigraphic ischemia and ischemia ST depression. Age, sex, prior myocardial infarction, and diabetes mellitus were not related to SMI. Patients with SMI had less severe ischemia despite a higher peak double product compared to those with painful ischemia. Among 91 with prior myocardial infarction and exercise-induced ischemia, 51 with periinfarction ischemia had a higher frequency of SMI than did 14 with ischemia remote from the prior infarct zone despite similarities in the severity of ischemia. In conclusion, factors localized within ischemic myocardium such as less severe ischemia or adjacency to a prior infarct made SMI more prevalent.

SPECT imaging with Tl-201 and Ga-67 in myocardial sarcoidosis.

Two patients with myocardial sarcoidosis are presented, both of whom underwent SPECT imaging with TI-201 and Ga-67. The first had Ga-67 myocardial uptake with a TI-201 defect, which disappeared with corticosteroid therapy. The second had multiple TI-201 defects without Ga-67 uptake, which persisted despite corticosteroid therapy. Therefore, the combination of TI-201 and Ga-67 imaging may be useful for recognizing myocardial sarcoidosis and for predicting the response to corticosteroid therapy.

Patent ductus arteriosus with Eisenmenger's syndrome detected by first-pass study.

The case of a 20-year-old man with patent ductus arteriosus complicated with Eisenmengers syndrome is described. Radionuclide angiocardiography characterized the abnormal pattern of blood flow through the central circulation to establish a diagnosis of patent ductus arteriosus with a significant right-to-left shunt, which had not been indicated by other clinical findings