Radioisotopic Techniques for Noninvasive Detection of Platelet Deposition in Bovine-Tissue Mitral-Valve Prostheses and in vitro Quantification of Visceral Microembolism in Dogs

Publisher Website
Google Scholar
Abstract
Platelet deposition on bovine pericardial-tissue mitral-valve prostheses in 11 dogs was observed noninvasively by use of 111In-labeled platelets and quantified after sacrifice at 1 (n = 3), 14 (n = 3) and 30 (n = 5) days postimplantation (300-400 .mu. Ci of labeled platelets having been injected 24 h previously). Thrombosis on the sewing ring and pericardial leaflets at 1 and 14 days and on the leaflets at 30 days was delineated in scintiphotos. In vitro quantification (% injected dose) indicated that the leaflets, sewing ring and perivalvular tissue retained 0.904% of labeled platelets at 1 day postimplantation, 0.198% at 14 days and 0.040% at 30 days. Platelet 1/2-life was reduced to 38 h at 21 days postimplantation but returned toward the normal (50 h) with fibrous ingrowth in the sewing ring. Microembolism in lung and kidney, as measured by tissue/blood radioactivity ratio, also was decreased significantly at 30 days. 111In-labeled platelets thus provide a sensitive marker for noninvasive imaging and in vitro quantification of platelet deposition on valvular prostheses and microemboli trapped in viscera, although histochemical confirmation will be necessary to correlate the increase in tissue/blood ratio with the presence of microembolism.