Retrieval and analysis of a clinical total artificial heart.
Examination by light microscopy, scanning electron microscopy (SEM), and x-ray microanalysis of a clinical total artificial heart (TAH) implanted for 112 days revealed no evidence of calcification, pannus, or vegetative thrombus. A macroscopic thrombus was seen along the suture line in the right atrium but did not obstruct blood flow or valve function. Microscopic thrombi (less than 0.1 mm) and evidence of microemboli were observed on the pumping diaphragm using SEM. Characterization of selected polyetherurethane (PEU) samples from the pumping bladders and housing by Curie-point pyrolysis mass spectrometry (Py-MS) revealed unexpected differences between postmortem retrieved ventricles. Although the origin of these differences could be traced back to batch-to-batch variations in the original PEU material (Biomer), the precise nature of the observed differences in chemical structure and/or composition is still unknown. Numerical comparison between pyrolysis mass spectra from PEU samples exposed to blood or tissue and unexposed samples from the same ventricles did not detect evidence of biodegradation. Continual improvements in fabrication and quality control should minimize surface imperfections and ensure polymer reproducibility; however, existing materials and design parameters appear to be adequate for continued clinical implantation.