Comparison of myocardial washout rate of thallium-201 between rest, dipyridamole with and without aminophylline, and exercise states in normal subjects

Symptom-limited arm exercise increases detection of ischemia during dipyridamole tomographic thallium stress testing in patients with coronary artery disease

Exercise combined with dipyridamole during thallium stress testing in patients with coronary artery disease (CAD) increases the frequency of angina and ischemic ST changes in the electrocardiogram. Evidence for an increase in thallium abnormalities has been inconclusive. We prospectively examined 54 consecutive patients who underwent coronary angiography and tomographic thallium with dipyridamole (0.57 mg/kg) alone and combined with symptom-limited dynamic arm exercise. Most patients presented with a history of chest pain and 49 had angiographic evidence of significant coronary stenosis (50% diameter narrowing). Thallium abnormalities were scored blindly by consensus. The number of abnormal segments (total and ischemic) and indexes of left ventricular dysfunction, such as increased lung uptake or ischemic dilation, were compared in the 49 patients with CAD. During arm exercise more patients had evidence of ischemia (39 vs 30; p < 0.001), and the number of ischemic segments increased significantly from 1.3 +/- 1.5 to 2.5 +/- 2.2 (p < 0.001). There was also a significant increase in the indexes of left ventricular dysfunction, ischemic dilation (10 vs 4 patients; p < 0.03) and increased lung uptake (16 vs 5 patients; p < 0.001). Patients who exercised had increased thallium evidence of extent and severity of ischemia and more frequent indexes of left ventricular dysfunction. Thus, symptom-limited arm exercise improves detection of extent and severity of ischemia in patients with CAD undergoing dipyridamole thallium stress testing.

Adenosine infusion to patients with ischaemic heart disease may provoke left ventricular dysfunction detected by echocardiography

Infusion of the endogenous vasodilator adenosine to patients with ischaemic heart disease (IHD) frequently provokes myocardial ischaemia, possibly caused by a coronary steal. The aim of this study was to detect the occurrence and incidence of disturbances in left ventricular (LV) wall motion and Doppler indices of altered LV function during infusion of adenosine. Thirty-seven patients (six female) aged 37-74 years with IHD, verified by coronary angiography, were given up to 200 micrograms kg-1 min-1 (mean 155 +/- 5) adenosine i.v. for 18 +/- 1 min. LV wall motion was monitored by two-dimensional echocardiography (2D-echo). Doppler spectral signal was obtained from the mitral blood flow. All but six of the patients experienced angina pectoris of habitual character in connection with the adenosine infusion. Heart rate increased by 22 +/- 1 beats min-1, systolic blood pressure was unchanged, but diastolic blood pressure decreased slightly. 2D-echo revealed severe regional LV wall motion disturbances already in the basal state in 17 patients. During infusion of adenosine, these abnormalities were aggravated and disturbances also occurred in another 15 patients. Thus, adenosine increased the sensitivity for IHD in this selected material from 49 to 89%. In all, the mean index of wall motion abnormalities increased from 5.1 +/- 1.1 to 10.1 +/- 1.4 (P less than 0.001). The diastolic LV filling characteristics, as evaluated by the Doppler A/E ratios, were of limited value for determination of IHD grade. It is concluded that infusion of adenosine to patients with IHD frequently elicits myocardial ischaemia with disturbances in LV function, and offers an alternative to exercise for stress echocardiography.

Pharmacological and other nonexercise alternatives to exercise testing to evaluate myocardial perfusion and left ventricular function with radionuclides

Pharmacological vasodilatation with either dipyridamole or adenosine is a safe and accurate alternative to exercise testing to diagnose coronary artery disease with thallium 201 myocardial perfusion imaging. The technique also provides important prognostic information with regard to future cardiac events in patients undergoing diagnostic testing, in those evaluated preoperatively, and in those with recent myocardial infarctions. Multigated equilibrium and first-pass radionuclide ventriculography also are well suited to evaluate the effects of interventional procedures. Success has been achieved using this methodology in a variety of interventions including conventional exercise testing, pharmacological stress testing, atrial pacing, assessment of myocardial viability with nitroglycerin, mental stress testing, and ambulatory monitoring of left ventricular ejection fraction.

Radiopharmaceuticals for imaging myocardial perfusion

A replacement for 201Tl used in myocardial perfusion imaging with a 99mTc-labeled complex is a long-sought goal. Now, at least three varieties of 99mTc-complexes are being made available for clinical studies. This review summarizes the development of these agents and presents basic research data accumulated in this area. Also, relevant clinical radiopharmaceutical protocols and relative merits of competing 99mTc-agents are discussed.