TIL: Bubble studies with late bubbles -> intrapulmonary shunt
When a bubble study is performed during a transthoracic echocardiogram (TTE), early bubbles suggest an intracardiac shunt1, which makes sense. Once agitated saline is inserted into the veins, it enters the right side of the heart. If bubbles immediately go to left side of the heart, there is theoretically through a hole like a patent foramen ovale.
When there are late bubbles, this suggests an intrapulmonary shunt. Bubbles typically don't travel through pulmonary capillaries, so late bubbles suggest that there is a shunt between pulmonary arteries and pulmonary veins. This can be a sign of hepatopulmonary syndrome2 or some other pathology that is known to cause an intrapulmonary shunt.
1. Tighe, Dennis A., and Gerard P. Aurigemma. "Right-to-Left Shunts and Saline Contrast Echocardiography." Chest 138.2 (2010): 246-248.
2. Khabbaza, Joseph E., Richard A. Krasuski, and Adriano R. Tonelli. "Intrapulmonary shunt confirmed by intracardiac echocardiography in the diagnosis of hepatopulmonary syndrome." Hepatology (Baltimore, Md.) 58.4 (2013): 1514.
