Doppler echocardiographic assessment of internal mammary artery flow after minimally invasive coronary artery bypass

Minimally invasive direct coronary artery bypass (MIDCAB) is a new technique for left internal mammary artery (LIMA) to left anterior descending bypass through a mini-thoracotomy without cardiopulmonary bypass. To evaluate noninvasive follow-up of these pts, 20 pts, aged 60±10 yrs, were studied by transthoracic Doppler after MIDCAB. All pts had intraoperative confirmation of LIMA patency. A 7 MHz linear array transducer (15 pts) or a 3.75 MHz phased array transducer (5 pts) was placed at the parasternal 2nd, 3rd, 4th intercostal space to record LIMA flow velocity. Right internal mammary artery (RIMA) flow velocity was recorded in 11 pts as a control (examples shown). All pts were studied 1-3 days after MIDCAB and 10 pts had additional studies in 1 month. Doppler data were available from 95% of attempted studies. LIMA and RIMA peak systolic velocity (S) and time velocity integral (TVI), peak diastolic velocity (D) and TVI, D/S, and D TVI % = [D TVI/(S TVI + D TVI)] were assessed: (mean values below, velocity in cm/sec). S S TVI D D TVI D/S D TVI % RIMA 77 17 16 6 0.4 26 LIMA (1-3 d) 59 14 39*18*1.2*55*LIMA (1 mo) 58 13 76*34*2.4*72*(*p < 0.01 vs. RIMA). Diastolic LIMA Doppler flow data were significantly > RIMA control, consistent with a distinct coronary artery flow pattern. These changes persisted after 1 month. Transthoracic Doppler may be useful to assess LIMA patency after MIDCAB.