The haemodynamic effects of N, N-bis(phenyl-carbamoylmethyl)
dimethylammonium chloride (QX-572) in man were studied. A controlled study was performed to rule out a possible influence of the catheterization procedure as such on the results. Ten patients with mild to moderate
aortic regurgitation were studied: based on clinical data the patients were divided into 2 groups of 5. Randomly it was decided that one group should constitute a control group receiving saline while the second group received
QX-572 , MG/KG
BODY WEIGHT. In both groups the administration was performed as a slow
intravenous infusion during 30 minutes. Heart rate, pressures in brachial artery and right atrium, cardiac output, stroke volume, and systemic vascular resistance were determined before, during, and up to 30 minutes after completion of placebo or
QX-572. These variable remained stable in the control group while
QX-572 produced an increase in heart rate most pronounced at the end of the infusion period. A transient decrease in systolic and mean brachial artery pressure during the infusion, and during the same period a decrease in right atrial pressure. Cardiac output and systemic vascular resistance were unchanged by
QX-572 but they were not measured during the infusion when the changes in pressures were most pronounced.
QX-572 was thought to act as a peripheral
vasodilator during the infusion. Left ventricular contractility was studied by means of pressure curves obtained from a
catheter tip manometer placed in the left ventricle. The first derivative of the isovolumic left ventricular pressure at the highest level (45mmHg) common to all patients was used (dp/dt-45). No significant difference could be observed when comparing mean changes of dp/dt-45 for the two groups. In the control group there was a slight but significant increase in dp/dt-45 during the time of observation. In the
QX-572 group the results varied between individuals. Two of the patients differed from all other patients in the control and
QX-572 groups showing a decrease in dp/dt-45 which, when most pronounced at the end of the infusion period, was -31 and -28 per cent of the preinfusion levels, respectively. This decrease probably reflects reduction of contractility. It was concluded that
QX-572 in a dose of 8 mg/kg
body weight did not have any major haemodynamic drawbacks.