Angina pectoris-like pain provoked by i.v. bolus of adenosine: Relationship to coronary sinus blood flow, heart rate and blood pressure in healthy volunteers

After finding the maximum tolerated i.v. bolus dose of adenosine, three fractions of this dose were given randomly to five volunteers in a double-blind manner. Pain, estimated by a 10-graded category-ratio scale, ECG and coronary sinus blood flow (CSBF), measured by thermodilution and intra-arterial blood pressure, were continuously recorded. At the highest tolerated dose (10.3 +/- 2.3 mg), the ECG showed short lasting (less than 5 s) AV-block but no ischaemic signs. Following the maximum dose, pain started 15 +/- 2 s after injection, reached a maximum (median 6 of 10 grades) after 25 +/- 4 s and disappeared after 62 +/- 7 s. Basal CSBF was 84 +/- 14 ml/min-1, and increased to 297 +/- 48 ml/min. The rise in CSBF started 2.4 +/- 0.8 s before pain appeared (P less than 0.05), but reached its peak 18 +/- 2 s after maximum pain (P less than 0.005). Although maximum coronary vasodilation was induced at the lowest dose of adenosine given--1/3 of the maximum dose--chest pain increased in a dose-dependent manner. When AV-block did not occur, diastolic pressure did not change from baseline, while systolic blood pressure increased by 5 +/- 2% (ANOVA, P less than 0.0001) and heart rate increased by 40 +/- 7% (ANOVA, P less than 0.0001). Following AV-block, except for a decrease of short duration in heart rate and systolic and diastolic blood pressures, the responses were similar. In conclusion, the vasodilator adenosine given as an i.v. bolus to human volunteers who were awake increased heart rate and systolic blood pressure with unchanged diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)