Effects of low-dose adenosine on myocardial performance after coronary artery bypass surgery

The effect of a non-hypotensive dose of adenosine infusion on myocardial performance after coronary artery bypass surgery was examined. Upon arrival at the intensive care unit, 16 patients (14 males, 2 females; mean age 64.5, range 46-71) were randomized to a blinded infusion of either low-dose adenosine (n = 8) or placebo (n = 8). The infusion continued at a rate corresponding to 30 micrograms.kg-1.min-1 of adenosine into the right ventricle over 4 h. Data were collected from the arterial line, thermodilution pulmonary artery catheter, transoesophageal echocardiogram (TEE), and 12-lead ECG on six occasions: before infusion, hourly during the infusion, and 1 h after terminating the infusion. Mean arterial blood pressure did not differ between the adenosine and placebo groups at any measurement point. Heart rate increased by approximately 15% during the first hour of adenosine infusion. Cardiac index increased by approximately 50% during infusion of adenosine and cardiac index remained higher while systemic vascular resistance remained lower in the adenosine-treated group during infusion. The E/A ratio (ratio between peak left ventricular inflow blood velocities during early filling and atrial contraction) was significantly higher in the adenosine-treated group after treatment for 1 h while the area injection fraction did not differ between groups at any time. The number of patients with ischaemic events as judged from ECG and from left ventricular regional wall motion abnormalities (RWMA) as visualized by TEE did not differ between groups (ECG: one patient in the adenosine group and one patient in the placebo group-RWMA: four patients in the adenosine group versus three in the placebo group).(ABSTRACT TRUNCATED AT 250 WORDS)