[Evaluation of internal thoracic artery bypass grafting with perfusion contrast echocardiography]

Intraoperative perfusion contrast echocardiography (PCE) is a new method to evaluate regional myocardial perfusion using Albunx (air encapsulated albumin microspheres-Molecular Biosystems, Inc.) and has been employed by direct individual injection into human saphenous vein coronary bypass grafts. Because this is not an appropriate technique for assessing left internal thoracic artery (LITA) graft, we tested the hypothesis that PCE can be performed with a single aortic root injection and, thereby, provide regional perfusion data for LITA and native coronary flow. CABG (LITA to the left anterior descending artery (LAD) was performed in adult swine. PCE was performed in each of the following conditions: 1) LITA occluded, LAD 100% flow; 2) LITA 100% flow, LAD occluded; 3) LITA 50% flow, LAD occluded; and 4) LITA and LAD occluded. Time-intensity curves were constructed to assess the time to initial appearance of myocardial enhancement (TIA), peak contrast intensity (PI), and area under the enhancement curve (AUC). In 12/14 cases, (85.7%), adequate enhancement was achieved. LITA perfusion, when compared to perfusion through the native LAD, showed delayed appearance (TIA 0.4 +/- 0.1 vs 1.9 +/- 0.2 secs), reduced PI (43 +/- 3 vs 28 +/- 3 AU) and reduced AUC (247 +/- 115 +/- 19 AU) (p < 0.01) when LITA flow was reduced 50%, TIA was prolonged (1.7 +/- 0.2 vs 2.4 +/- 0.2 secs) and AUC was reduced (152 +/- 18 vs 88 +/- 20 AU) (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)