Localization of In-111 antimyosin Fab and 99mTc-pyrophosphate in reperfusion myocardial infarction model

Abstract

The myocardial uptake of In-111 antimyosin Fab and Tc-99m pyrophosphate was studied in dogs undergoing coronary artery occlusion for 90 minutes followed by reperfusion. The regional myocardial blood flow was determined by injecting Sc-46 labeled microsphere and was related to the relative concentrations of In-111 antimyosin and Tc-99m pyrophosphate. There was an inverse linear correlation between In-111 antimyosin Fab localization and the regional blood flow in both the subendocardial (r = 0.81) and subepicardial myocardium (r = -0.80). The greatest uptake of antimyosin was observed in areas of severe blood flow reduction (0-10% of normal). On the other hand, there was no correlation between the Tc-99m pyrophosphate uptake and the degree of blood flow reduction. Maximal subendocardial localization of Tc-99m degree of blood flow reduction. Maximal subendocardial localization of Tc-99m pyrophosphate was observed in areas where the blood flow was reduced to 31-50% of the normal. In the case of the subepicardium, the greatest uptake was localized to areas of 0 to 10% of the normal flow. In addition, there was significant myocardial uptake in regions where the blood flow was minimally reduced (greater than 81%). This study suggests that In-111 antimyosin Fab is a specific and quantitative tool in the evaluation of myocardial necrosis.

Fig. 1.

Experimental protocol (* : left anterior descending coronary artery, # : antimyosin, : pyrophosphate)

Fig. 2.

Relative localization of Tc-99m pyrophosphate and In-111 antimyosin Fab in relation to regional blood flow in all subendocardial samples.

Fig. 3.

Relationship between myocardial perfusion and Tc-99m pyrophosphate uptake, and regional blood flow and In-111 antimyosin Fab uptake in subendocardial samples. Each point represents the mean±SEM uptake ratio.

Fig. 4.

Relative localization of Tc-99m pyrophosphate and In-111 antimyosin Fab in relation to regional blood flow in all subepicardial samples

Fig. 5.

Relationship between myocardial perfusion and Tc-99m pyrophosphate uptake, and regional blood flow and In-111 antimyosin Fab uptake in subepicardial samples. Each point represents the mean±SEM uptake ratio

Fig. 6.

Comparison of subendocardial and subepicardial distribution of Tc-99m pyrophosphate and In-111 antimyosin Fab in relation to myocardial blood flow. (Subendo: subendocardium, Subepi: subepicardium, * : P not significant, ** : P<0.001, *** : P<0.05).