[Effects of the new cardiotonic agent TA-064: serial computer-assisted analyses of pressure-volume relations and online myocardial 02 consumption]

Abstract

According to investigations conducted in Japan, TA-064 is a new cardiotonic agent, which is also effective orally. We analyzed computer-assisted alterations of pressure-volume relations serially and of MVO2 online (Bretschneider) during TA-064 influence in 16 patients with congestive cardiomyopathy: LV-function of 7 patients was only moderately decreased (group A) and in 9 patients massively (group B).

Results: 1) TA-064, 8 micrograms/kg/min, i.v. had positive inotropic effects in both groups and induced mean maximal delta% changes at about the 5th minute of infusion as follows: LVSWI + 65% and 47%; DP/DTmax + 61% and 59%; LV-efficiency + 62% and 53%; MVO2 + 31% and + 11% (p less than 0.05). 2) TA-064, 20 mg p.o. induced serum levels (A: 23.8 +/- 12 and B: 26.4 +/- 20 ng/ml) corresponding to the effects with the dosages 1-2 micrograms/kg/min, i.v. (p greater than 0.05), thus implying that significant changes in LV-function require higher p.o. dosages. 3) TA-064 i.v. on the 6th day of exposure to the medication produced less LV-function improvement than on day 1 (p greater than 0.05).

Conclusions: In both groups A and B TA-064 improves LV-function primarily via increased contractility, without toxic side effects. For a more complex definition of the efficiency and mechanism of cardiotonic agents, the validity and importance of using on-line MVO2 assessment and analysis of serial pressure-volume relations is stressed.