Cardiovascular Effects of Sustained Norepinephrine Infusions. II. Morphology

The major toxic effect of norepinephrine (NE) infusion in dogs, cats, and rabbits in doses relatively comparable to those used clinically has been shown to be on the heart. Noncardiac lesions were those of congestion, and were seen in animals receiving the higher doses. The dogs in these dose groups showed evidence of progressive deterioration of cardiac function. All dogs which developed cardiac lesions also developed an acute adrenalitis. The cardiac lesions in all animals consisted of focal degeneration and necrosis of myofibers, and subendocardial hemorrhage. These lesions healed within two weeks by fibrosis.