Failure of hyaluronidase to alter the early course of acute myocardial infarction in pigs

The effect of hyaluronidase on the early course of acute myocardial infarction was evaluated in closed chest anesthetized pigs. One hour after balloon catheter occlusion of the left anterior descending coronary artery, hyaluronidase (500 units/kg body weight) was rapidly infused in 10 animals while 9 received no treatment. The animals were then observed over the next 4 hours. Cardiac output, heart rate, mean arterial pressure and left atrial pressure were not significantly affected by treatment. Heart rate increased and arterial pressure decreased in each group to a comparable degree by 5 hours, but left atrial pressure and cardiac output were unaffected.Precordial S-T segment mapping revealed no significant difference between the two groups. S-T segments rose to a comparable degree in each group and peaked before 1 hour. Hyaluronidase had no acute effects on the S-T segment map in the first 30 minutes after infusion or during the subsequent return of the map toward control level. Slightly lower S-T segments in the hyaluronidase-treated group at 5 hours was of borderline significance but was attributed to factors other than the drug intervention. Changes in ventricular wall motion were assessed angiographically, and all animals manifested akinetic or dyskinetic segments. A significant reduction in shortening fraction of involved segments was seen after occlusion, but no difference was observed between the two groups at 5 hours. Shortening fraction of the combined anterior and anteroapical segments decreased from 66 ± 10 to 20 ± 6 percent at 5 hours in the hyaluronidase group (no. = 7) whereas in the control group (no. = 6) it decreased from 68 ± 6 to 28 ± 9 percent. Comparable increases in end-dlastolic volume were also present at 5 hours in each group. Volumes increased from 80.6 ± 5.1 to 97.5 ± 6.4 ml³ at 5 hours (P < 0.05) in the hyaluronidase-treated group (no. = 10) compared with 86.9 ± 8.9 to 104.8 ± 11.0 ml³ (P < 0.05) in the control group (no. = 8).Hyaluronidase did not alter the early course of acute myocardial infarction in pigs. Species differences may contribute to different results reported to date.