Morphometric analysis of heparin coated versus standard intra-aortic balloons

The adverse effects of systemic heparin administration has led to the development of heparin coated devices. Intra-aortic balloons are frequently used in clinical settings in which complications of systemic heparin, especially bleeding, are feared. The current study evaluated the thromboresistance of heparin coated intra-aortic balloons. Six bovine calves were chosen for the experiment. In each animal, three intra-aortic balloons were inserted, and set to the automatic mode: two in the vena cava for 15 min and 45 min, respectively, and one in the aorta for 6 hr. There were nine standard and nine heparin coated intra-aortic balloons. At the end of the procedures, three samples of each intra-aortic balloon were analyzed with scanning electron microscopy for computed analysis of the balloon surface covered with fibrin and cells. The scanning electron microscopy analysis showed no deposit at any time interval on the heparin coated sample surfaces, whereas 3.6% +/- 9.2% (mean +/- SD) of the standard sample surfaces were covered with deposits at 15 min (p = 0.06), 14.8% +/- 24.3% at 45 min (p = 0.01), and 4.4% +/- 12.4% at 6 hr (p = 0.06). Strikingly, none of the 27 heparin coated samples showed any microscopic deposits, whereas 11 of the 27 standard samples did (p < 0.002). Heparin coated intra-aortic balloons appear to be a promising strategy, especially for patients with absolute or relative contraindications to systemic heparinization.