Right-heart echocontrast in the anesthetized dog after i.v. administration of a new standardized sonographic contrast agent. 2nd communication: dependence of the intensity of contrast on the interval between preparation of the suspension and its injection.
The right-ventricular echocontrast provided by 5 different concentrations of the new standardized sonographic contrast agent SH U 454 (100, 150, 200, 300 and 400 mg microparticles/ml), which consists of pure galactose microparticles, was examined in 3 anesthetized female beagle dogs (8.6-9.3 kg) in order to assess the influence of the period of time which elapsed between preparation of the suspension and its injection. Each animal was given 2 ml of an SH U 454 concentration by intravenous injection at a speed of approximately 2 ml/s immediately after preparation of the suspension and 1, 2, 3 and 5 min thereafter. Evaluation of the intensity of contrast was performed blind by two investigators working independently and using a visual scoring system (ratings 0-5) and also by a videodensitometer. The videodensitometer provided a quantitative evaluation of the maximum intensity of contrast, the duration of contrast and the area under the videodensitometer curve. The intensity of the contrast of the prepared suspension subsided at a constant rate over a period of 5 min for all the concentrations tested. However, the difference between the starting value t0min and the terminal value t5min was small. On the whole, very little difference was found over the 5-min period in the intensity of the contrast provided by any of the SH U 454 concentrations examined. Thus, for the injection the examiner has a timeframe of at least 5 min after preparation of the suspension.