Correlation of gross and microscopic appearance of skin buttons in total artificial heart animals

Pneumatic artificial hearts are powered by compressed air that is delivered through percutaneous tubes. A stress relief device, termed a skin button, surrounds these tubes as they exit from the recipient's tissues. The skin button is designed to protect the tissues from damage and provide a secure material-tissue interface. Prevention of superficial and invasive infection is the primary goal of the skin button. Eight calves were studied prospectively to identify gross or microscopic infection with the skin button. All animals who survived more than sixty days (62-136) had both gross and microscopic evidence of infection. All animals surviving less than 60 days (13-43) had no gross evidence of infection but one had subcutaneous microscopic abscess formation. No animal died secondary to a skin button infection. Skin buttons cannot prevent infection but they can contain the pathologic process in the superficial tissues with no evidence of systemic effects.