The Effects of Increase in Heart Rate on Coronary Flow Reserve and Flow Profiles : A Study with Intracoronary Doppler Wire

Kim, Han Soo; Tahk, Seung Jea; Shin, Joon Han; Cho, Yun Kyung; Kim, Won; Ku, Bon Kwon; Choi, Byung Il

Abstract

BACKGROUND
Measurements of coronary flow reserve(CFR) and phasic coronary flow profile are useful in assessment of the physiologic significance of coronary lesions. However, alterations in hemodynamic status are known to influence coronary flow reserve. The purpose of this study was to assess the effect of increase in heart rate on maximal pharmacologin coronry flow reserve and phasic flow pattern.
METHODS
We investigated 12 patients(9 females and 3 males, mean age : 49+/-12 years) with normal coronary artery and atypical chest pain syndrome for the measurement of CFR and coronary flow profile. CFR and systolic and diastolic coronary flow velocity integral(CFVI) were measured at the proximal portion of left anterior descending artery with 0.018 inch(12MHz) Doppler guide wire before and during intracoronary injection of 12 mcg of adenosine. The heart rate at the baseline ranging from 62 beats/min to 79 beats/min(mean : 70+/-5 beats/min) was increased to 100 beats/min and again to 120 beats/min by right atrial pacing.
RESULTS
CFR progressively decreased from 3.0+/-0.5 at baseline to 2.4+/-0.4 during pacing at 100 beats/min and to 2.0+/-0.3 during pacing at 120 beats.min(p<0.001). CFVI/min at baseline was progressively increased(130+/-15% of control value at 100 beats.min, 135+/-30% at 120 beats.min(p<0.01) whereas in adenosine hyperemia remained unchanged(286+/-81% at hyperemia baseline, 296+/-91% at 100 beats/min, 289+/-105% at 120 beats/min, p>0.05). Systolic CFVI/min was increased at baseline(185+/-35% at 120 beats/min, p<0.01) and in adenosine hyperemia(377+/-153% at hyperemia baseline, 457+/-178% at 120 beats/min, p=0.01). Diastolic CFVI/min was increased at baseline(134+/-178% at 120 beats/min, p<0.01), but in adenosine hyperemia, no significant change was observed(278+/-77% at hyperemia baseline and 251+/-77% at 120 beats/min, p>0.05).
CONCLUSION
Increase in heart rate induces a substantial reduction in maximal CFR. Thus,heart rate appears to be one of important variable for the measurement of CFR and phasin coronary flow profile.