Potential use of transthoracic echocardiography in the assessment of coronary flow reserve

Coronary flow reserve provides a gold standard assessment of the epicardial and microvascular coronary circulation. However, measurement of coronary n ow reserve is limited by the invasiveness or complexity of the methods hith erto available. We investigated whether transthoracic echocardiography coul d be used to assess coronary flow reserve. We imaged distal left anterior d escending coronary artery diameter and now in 14 healthy volunteers, both a t rest and during intravenous infusion of adenosine (140 mu g/kg per minute ). Volunteers were men, with an average (+/-SD) age of 28.4+/-6.3 pears. Co mplete data were acquired in 11 cases. Average distal left anterior descend ing coronary artery diameter was 0,213 +/- 0.03 cm. velocity time integral rose from 8,6 +/- 2.1 cm to 27.7 +/- 5.6 cm with adenosine infusion. Heart rate rose from 64.7 +/- 9.8 to 75.3 +/- 11.7 bpm. The Doppler angle of inci dence to flow was 42.4 +/- 8.7 degrees. Resting distal left anterior descen ding coronary artery flow was therefore calculated as 13.4 +/-: 3.2 mL/min and hyperemic flow as 51.2 +/- 16.2 mL/min, yielding a coronary flow reserv e of 3.81 +/- 0.6. We conclude that:coronary flow reserve can be assessed i n a selected population with the use of transthoracic echocardiography and an Intravenous infusion of adenosine, The simplicity of this noninvasive te chnique suggests that it could become a useful tool for measurement of coro nary now reserve if imaging success rates can be optimized.