Importance of Adequate Heparin Dosage in Arterial Angioplasty in a Porcine Model

Acute occlusion after a successful angioplasty is a severe complication that has been reported in 2-12 % of patients. Therefore, to determine whether there was a relation between the dosage of heparin and the presence of mural thrombosis, we studied in a pig model the relation between the dosage of heparin and acute platelet-thrombus deposition on the site of arterial injury. We retrospectively analyzed the effect of three heparin regimens on platelet deposition in 32 normal pigs (mean weight, 32.7 kg) that underwent bilateral carotid angioplasty and were sacrificed 90 26 minutes later. Pigs in protocol 1 (n = 7) received an intravenous bolus injection of 4,000 units heparin 10 minutes before angioplasty. Pigs in protocol 2 (n =11) received two bolus injections of 4,000 units heparin 40 minutes apart; the angioplasty was performed immediately after the second bolus. Pigs in protocol 3 (n = 14) had an initial 4,000-unit bolus injection of heparin followed immediately by an infusion of 4,000 units/hr; angioplasty was performed 20 minutes after starting the infusion. "'In-labeled platelet deposition on deeply injured (torn into the media) arterial segments were 86.3 68, 56.2 56.9, and 37.7 37.7 x 106/cm2 for protocols 1, 2, and 3, respectively. A regression analysis showed an inverse relation between the log of platelet deposition and heparin units per kilogram per minute in arterial segments with dee