Myocardial infarct size reduction by the synergistic effect of hyperbaric oxygen and recombinant tissue plasminogen activator.

Fasting mongrel dogs underwent hyperbaric oxygen treatment (HBOT), recombinant tissue plasminogen activator (rt-PA) treatment, and simultaneous HBOT and rt-PA treatment following prior experimental left anterior descending coronary artery occlusion for 2 hours. Thrombosis in and around a copper coil was recorded angiographically at regular intervals, and immediately prior to treatment conclusion. Controls (n = 10) were untreated. Group two animals (n = 10) were treated additionally with 90 minutes of HBOT at 2 atm absolute. Group three animals (n = 8) were treated additionally with 50 mg rt-PA over 90 minutes. Group four animals (n = 10) were treated additionally with simultaneous HBOT and rt-PA over 90 minutes. Myocardial injury was determined by a combination of triphenyltetrazolium chloride histochemical staining and by formazan dye extraction. Damage was measured as a percent of left ventricular cross-sectional area studied. HBOT alone restored 35.9% of oxidative enzyme activity (p greater than 0.001). Treatment with rt-PA alone restored 48.9% of enzyme activity (p greater than 0.001). The combination of HBOT and simultaneous rt-PA resulted in 96.9% restoration of oxidative enzyme activity versus the control group (p greater than 0.001).