SAFETY OF SINGLE-SITE ADENOSINE TL-201 SCINTIGRAPHY

The diagnostic accuracy, safety and tolerance of adenosine thallium sc intigraphy have been reported using a 2-site intravenous infusion with either a titrated or fixed-dose protocol. A single-site infusion woul d considerably simplify the test procedure, but its safety must be est ablished before it can be recommended. Accordingly, 400 consecutive pa tients who had adenosine and thallium-201 administered through the sam e intravenous line were classified into 2 groups. Group I (n = 201) pa tients received a 7-minute titrated intravenous infusion of adenosine, with an initial dose of 50 mug/kg/min that increased at 1-minute inte rvals to a maximum of 140 mug/kg/min. Group II (n = 199) patients rece ived a fixed dose of adenosine at 140 mug/kg/min for 6 minutes. Adenos ine significantly (p < 0.001) increased heart rate and decreased systo lic blood pressure by similar amounts in both groups. Adverse effects occurred more often (88 vs 71%, p < 0.001) and started earlier (2.8 vs 3.6 minutes, p < 0.001) in group II. There was no significant differe nce in the occurrence of second- and third-degree atrioventricular blo ck between the 2 groups (4.0 vs 5.0 %); however, chest pain, flushing and nausea were all more frequent in group II. Severe side effects wer e seldom seen in either group and occurred in 9 group I and 8 group II patients. Scintigraphic findings were similar in both groups. Transie nt perfusion defects were seen more often in patients with than withou t second- or third-degree atrioventricular block (42 vs 21%, p < 0.05) . Despite a high frequency of side effects for both the fixed dose and stepwise infusion regimens, adenosine and thallium administration thr ough a single intravenous site is safe and well-tolerated.