FLOW DYNAMICS OF ANGIOGRAPHICALLY NO-FLOW PATENT INTERNAL MAMMARY ARTERY GRAFTS

Objectives. This study sought to assess the flow dynamics of internal mammary artery grafts (IMAGs) in no-flow situations by use of a Dopple r guide wire. Background. Functionally no-flow and anatomically patent IMAGs have been reported by angiography in patients with a patent rec ipient coronary artery. Methods. The study included 12 patients with a n IMAG to the left anterior descending coronary artery (LAD) in whom n o-flow patency of the graft was suspected angiographically. Thirteen p atients with a normally functioning IMAG whose LAD was occluded in the proximal portion and was supplied only from the graft served as contr ol patients. Phasic flow velocities were recorded in the distal portio n of the graft and the recipient LAD using a 0.014-in., 15-MHz Doppler guide wire at rest and during hyperemia (0.14-mg/kg body weight per m in intravenous adenosine infusion). Results. There were no significant differences in systolic (15 +/- 3 vs. 19 +/- 6 cm/s, p = NS), diastol ic (35 +/- 11 vs. 37 +/- 7 cm/s, p = NS) and time-averaged peak veloci ties at rest (20 +/- 5 vs. 21 +/- 5 cm/s, p = NS), during hyperemia (5 1 +/- 12 vs. 51 +/- 8 cm/s, p = NS) and in coronary flow velocity rese rve (2.8 +/- 0.9 vs. 2.7 +/- 0.3, NS) in the native LAD in patients wi th a no flow patent graft versus control patients. Within the graft, t o and fro signals with systolic reversal and diastolic anterograde flo w were seen in the no-flow patent grafts, although anterograde flow si gnals were recorded in systole and diastole in control patients. Systo lic (-28 +/- 19 vs. 22 +/- 9 cm/s, p < 0.01), diastolic (18 +/- 17 vs. 44 +/- 11 cm/s, p < 0.01) and time-averaged (-2 +/- 6 vs. 26 +/- 9 cm /s, p < 0.01) peak velocities at rest were significantly smaller in th e no-flow patent grafts than in control grafts. During hyperemia, ante rograde flow became predominant, with a reduction in retrograde systol ic flow signal and an increase in diastolic flow velocity and time-ave raged peak velocity in the no-flow patent grafts, and no-flow situatio ns disappeared temporarily. Conclusions. Functionally no-flow situatio ns of IMAGs manifesting to and fro signals with systolic flow reversal and diastolic antegrade low flow velocity are temporary conditions in certain hemodynamic circumstances, and these grafts function as condu its during hyperemic states. (C)1998 by the American College of Cardio logy.