Mammary artery coronary grafts: Patency assessment and functional evaluation by color Doppler

Background. Left internal mammary artery coronary graft patency is usually evaluated invasively by cardiac catheterization. The objective of this stud y was to assess the ability of a high-frequency transthoracic Doppler echoc ardiographic system in the evaluation of patency and flow velocities change s in left internal mammary artery. Methods. Twenty-two patients (63 +/- 9 years, 17 male) who had previously u ndergone left internal mamary artery to leff anterior descending artery wer e evaluated by transthoracic echocardiography, with an Acuson Sequoia C256 equipment (Acuson, Mountain view, USA), placing the transducer (5 MHz) in t he second-third left intercostal space. Left internal mamary artery flow wa s considered to be found in the presence of one systolic/diastolic byphasic blood flow. Dipiridamol 0.5 mg/kg was administered in absence of contraind ications in order to evaluate the flow reserve. Results. In 16 patients (73%), a byphasic systolic-diastolic flow was visua lized. Peak velocity of systolic and diastolic waves was 38 +/- 13 and 37 /- 15 cm/s, respectively. Eleven patients received i.v. dipiridamol 0.5 mg/ kg. After dipiridamol, systolic and diastolic velocities rose from 32 +/- 8 to 43 +/- 14 cm/s (p = 0.0429) and from 25 +/- 8 to 50 +/- 17 cm/s (p = 0. 0002), respectively (an increasing of 33 +/- 22% and 103 +/- 46% over the b aseline, respectively). Conclusion. This descriptive study shows that a non-invasive functional eva luation of left internal mammary artery grafts by a transthoracic approach with a high-frequency echocardiographic equipment is possible.