succimer and Myocardial-Infarction

Technetium-99m 2,3-dimercaptosuccinic acid (Tc-99m DMSA) has been used successfully for imaging acute myocardial infarction in a canine model. The application in humans, however, has not been previously reported. In order to determine the feasibility of using this agent in clinical studies and to compare the agent to technetium-99m pyrophosphate (Tc-99m PPi), ten patients with proven myocardial infarction were studied. While imaging of transmural infarctions in humans was achieved using Tc-99m DMSA, scores for the Tc-99m DMSA images (1.8 +/- 0.96) were not as high as for Tc-99m PPi (2.5 +/- 0.45) (P less than 0.05). Discordance among four independent interpreters was greater for images obtained with Tc-99m DMSA. The superiority of Tc-99m PPi was evident whether images were obtained early (within 24 hours) or late (within five days). Although DMSA images were not obscured by rib uptake, they were less sensitive (63%) than Tc-99m PPi (97%). A potential advantage of Tc-99m DMSA in imaging acute myocardial infarction is that radiotracer concentration in the infarct occurs primarily in the early postinfarction period. The longer postinfarction that Tc-99m DMSA imaging was attempted, the lower the concentration of radiotracer. Thus, Tc-99m DMSA would not be expected to have the same persistence pattern as Tc-99m PPi into the remote postinfarction period. The persistent positivity of Tc-99m PPi has made it difficult to diagnose reinfarction.

Topics: Aged; Animals; Diphosphates; Dogs; Humans; Kinetics; Male; Middle Aged; Myocardial Infarction; Myocardium; Organometallic Compounds; Radionuclide Imaging; Species Specificity; Succimer; Sulfhydryl Compounds; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid; Technetium Tc 99m Pyrophosphate; Time Factors

Topics: Animals; Dogs; Heart; Myocardial Infarction; Radionuclide Imaging; Succimer; Sulfhydryl Compounds; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid

Acute myocardial infarctions were produced by ligature of the left frontal descending coronary artery in 9 dogs. The possibility of scintigraphic imaging with 99mTc-DMSA 4 hrs after intravenous administration was studied. The infarctions were 4, 24 and 48 hrs old. The in vivo scan was positive in only one dog with a 4-hr old infarction. The in vivo scans were confirmed by the analysis of the radioactivity in tissue samples. The accumulation of the radiopharmaceutical increased slightly in 48-hr old lesions; however, this increase was not sufficient for a positive scintigraphic finding. Thus, we do not recommend 99mTc-DMSA for clinical use in acute lesions.

Topics: Animals; Dogs; Myocardial Infarction; Radionuclide Imaging; Succimer; Sulfhydryl Compounds; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid

We have studied the use of Tc-99m-labeled 2,3-dimercaptosuccinic acid (Tc-99m DMSA) to scintigraph acute myocardial infarction after coronary occlusion in dogs. Optimal images were obtained 5 hr after injection of radiotracer, with consistent delineation 48 hr after occlusion. Delivery of tracer was dependent on blood flow. Uptake of tracer correlated to extent of infarction as determined by the myocardial depletion of creatine kinase. Myocardial Tc-99m DMSA was protein-bound.

Topics: Animals; Coronary Circulation; Coronary Disease; Creatine Kinase; Dogs; Half-Life; Myocardial Infarction; Radionuclide Imaging; Succimer; Sulfhydryl Compounds; Technetium; Time Factors; Tissue Distribution

The pharmacodynamics of several tin compounds were studied in healthy rabbits, rabbits with myocardial infarcts, and isolated myocardial tissue. The results showed that tin chelates of pyrophosphate, HEDP, DTPA, and glucoheptonate are very unstable in vivo, giving rise to free stannous ions. These ions localize mainly in bone, with the rest being primarily excreted in the urine. They also concentrate more in infarcted than in normal myocardium; there they enter the mitochondria. The supernatant of homogenates contains bound and free fractions, demonstrating a subcellular distribution pattern similar to that of calcium ions. Tin chelates have different pharmacodynamics from the corresponding 99mTc chelates.

Topics: Animals; Autoradiography; Chelating Agents; Diphosphates; Femur; Male; Myocardial Infarction; Myocardium; Rabbits; Radioisotopes; Succimer; Technetium; Time Factors; Tin; Tissue Distribution