| Abstract: | M-mode and two-dimensional subcostal contrast echocardiography were used in 67 patients and 10 normal subjects to evaluate the contrast echo effect on the inferior vena cava echogram in relation to the cardiac cycle and respiratory events. No contrast echoes were recorded in the inferior vena cava in normals during normal breathing. Contrast echoes were recorded entering the inferior vena cava in systole in 20 patients with tricuspid regurgitation and in pre-systole in patients with atrial septal defect and left-to-right shunt and in some of the patients with elevated right atrial and ventricular end-diastolic pressure. Forced inspiration increased the contrast echo effect and determined the penetration of microbubbles into the inferior vena cava. This latter feature occurred in all the patients and only in 1 normal subject. The entry of the contrast echoes into the inferior vena cava was attributed to the high right atrial ventricular end-diastolic pressure and to the reversed flow, from the right ventricle to the right atrium and inferior vena cava in tricuspid regurgitation and from the left atrium to the inferior vena cava in atrial septal defect. The contrast echocardiographic diagnosis of tricuspid regurgitation appeared to be most reliable. New encouraging results were obtained by this technique in diagnosing atrial septal defect and left-to-right shunt. The first appearance of the contrast, the time of appearance in relation to the cardiac cycle and the direction of the to and fro motion of contrast echoes were the most important factors considered for a correct diagnosis. |
