Value and limitations of intracoronary adenosine for the assessment of coronary flow reserve

An ideal coronary vasodilator for studying coronary flow reserve should rapidly produce a maximal hyperemic response, be short acting to permit repeated measurements, and not alter systemic hemodynamics. We measured with a Doppler tip balloon catheter, in 12 patients before and/or after percutaneous transluminal coronary angioplasty the hyperemic response following 12.5 mg intracoronary papaverine and following gradually incremental bolus injections of intracoronary adenosine, starting from 0.05 mg until a maximal hyperemic response or side effects. The mean dose (+/- SD) of adenosine needed to produce maximal hyperemia was 0.23 (+/- 0.20 mg). Coronary blood flow velocity after adenosine increased to 1.6 +/- 0.3 times resting coronary blood flow velocity, comparable in magnitude to the hyperemia following intracoronary papaverine. The time from injection to peak effect after adenosine was 7.4 (SD +/- 2.2) sec and after papaverine 26 (SD +/- 7) sec. Adenosine resulted in a bradyarrhythmia in three patients. Intracoronary adenosine is a potent and very short acting vasodilator for studying coronary flow reserve, but the side effects and unpredictability of the dosage needed to produce maximal hyperemia may limit its applicability.