The CARDIOX Flow Detection System is designed to detect the presence of indocyanine green (ICG) dye in the blood and is being investigated to establish its efficacy in detecting the presence of right to left cardiac shunt (RTLS). The CARDIOX system will be compared against transesophageal echocardiography (TEE) for sensitivity and specificity, as well as transcranial doppler (TCD) for positive percent agreement and negative percent agreement.