Background: The method to induce coronary hyperemia with maximal and steady state is important to evaluate microvascular circulation by coronary flow reserve(CFR) and fraction flow reserve(FFR). We compared the method of induing hyperemia between intra-coronary(IC) adenosine bolus injection and IC continuous infusion.
Methods: CFR was evaluated in thirty-six coronary lesions(LAD 23, LCX 5, RCA 8) in 23 patients(male 18, mean 58짹12 y; SA 2, UA 12, AMI 9) and FFR was evaluated in twenty lesions(LAD 13, LCX 6, RCA 1) in 10 patients(male 8, mean 60짹11 y; SA 1, UA 7, AMI 2). To induce maximal coronary hyperemia, two methods were applied to same patient; Method A(IC adenosine bolus injection(RCA 24關g, LCA 48關g)) and Method B(IC adenosine continuous infusion(240關g/min). CFR was defined as a ratio of hyperemic(hAPV) to baseline APV(bAPV). FFR was defined as a ratio of mean aortic pressure to mean coronary pressure of distal part to lesion during maximal hyperemia. Hyperemic average peak velocity(hAPV, cm/sec), CFR and FFR were compared with paired t-test in two methods.
Results: All patients were tolerable during maximal hyperemic period. During maximal coronary hyperemia, heart rate and mean blood pressure were not different between two methods. Transient AV block occurred in 2 patients with method A and in 2 same patients with method B. The duration of maintenance of hyperemia was mean 24.6짹5.4 seconds in method A and all patient except 2 patients were maintained stable hyperemia with method B during continuous infusion of adenosine. CFR and hAPV were significantly higher in method B than A(3.4짹2.1 vs. 2.9짹1.2, p=.01 ; 52.5짹23.4 vs. 45.7짹19.9, p<0.01, respectively). FFR was significantly lower in method B than A(0.76짹0.17 vs. 0.80짹0.15, p<0.01).
Conclusion: Compared with intracoronary adenosine bolus injection method(24-48關g), intracoronary adenosine continuous infusion method induced more effective and stable for inducing maximal hyperemia.