Saline Solution
The use of ultrasound contrast enhanced detection of the PFO relative to PW Doppler color. Recent studies have shown that a transthoracic echo contrast with comparable accuracy with a transesophageal echo.
Contrast is a mixture of 8 ml physiological saline ( NaCl ) with 0.5- 1.0ml air and 0.5- 1.0ml blood. First, we look without Valsalva does this not result then still Valsalva what better detection result is. A contrast echo is done with a AP4Ch or subcostale4Ch recording. The contrast is in the right atrium to. In a positive test is seen crossing to the left atrium. The number of heart beats have to be counted. If there is seen in the LA contrast within 3 cardiac cycles is considered an intracardiac shunt. It takes longer than three cardiac cycles are called an intrapulmonary shunt.
The risk of contrast ultrasound is very low , according to a study by the American Society of echocardiography there is about 0:06 % chance of a side effect of contast by saline.