Effect of ionic and non-ionic contrast medium on aortic and pulmonary arterial pressure. An angiocardiographic study in rabbits.

Effects in angiocardiography from injections into the right atrium of rabbit hearts of a new, non-ionic contrast medium (Amipaque) were studied and were compared with the effects from injections of an ionic medium (Isopaque Coronar) at a dose of 3 ml/kg rabbit and concentration of 370 mg I/ml. Forty-seven experiments in 11 rabbits are reported. Amipaque produced a significantly (p less than 0.001) smaller increase in pulmonary arterial pressure (29%) than Isopaque Coronar (82%). Simultaneously (within 12 seconds from the beginning of an injection) Amipaque produced an increase in aortic pressure of 21%. About 10-15 seconds later when the contrast media had reached peripheral vessels Amipaque produced a significantly (p less than 0.001) smaller decrease of aortic pressure (12%) than the decrease produced by Isopaque Coronar (40%). The differences found between the two types of contrast media are believed to be related to, among other factors, their different osmolality. The osmolality of Amipaque was about one third of the osmolality of Isopaque Coronar.