Correlation between the demethylation rate of 14C-aminopyrine (breath-test) and haemodynamic parameters in congestive heart failure.

In 18 patients with congestive heart failure, the 14C-aminopyrine demethylation rate was studied by the breath-test, 24 hours after the measurement of haemodynamic parameters. In the 12 patients with a cardiac index higher than 2.2 l/m2/min, the half life of 14CO2 specific activity in breath was found to be significantly correlated (p less than 0.001, r = 0,82) with the telediastolic pressure of the right ventricle. On the other hand, in the 6 patients with a cardiac index below 2.2 l/m2/min the 14C-aminopyrine half life was higher than the value predicted by this correlation. Congestive heart failure probably reduces hepatic demethylation of aminopyrine through altered hepatic microsomal function associated with congestion and possibly hypoxia.