From the Guidelines
Intrapulmonary shunting with agitated saline contrast is a crucial diagnostic tool for identifying right-to-left shunts, and its clinical significance lies in distinguishing between intrapulmonary and intracardiac shunts, which is essential for proper patient management and treatment decisions. The procedure involves injecting agitated saline into a peripheral vein while performing an echocardiogram, and the appearance of bubbles in the left heart chambers can indicate the presence of a shunt. According to 1, saline contrast echocardiography is a useful tool for detecting intracardiac or transpulmonary right-to-left shunts, and it is more sensitive than Doppler echocardiography for detection of low-velocity right-to-left shunts.
Some key points to consider when using intrapulmonary shunting with agitated saline contrast include:
- The distinction between intrapulmonary and intracardiac shunts is crucial for proper diagnosis and management of hypoxemia, cryptogenic stroke workup, and pre-transplant evaluations, particularly for liver transplant candidates 1.
- The test is relatively simple to perform during a standard echocardiogram and provides valuable diagnostic information that may significantly impact patient management decisions.
- Intrapulmonary shunts are commonly seen in hepatopulmonary syndrome, pulmonary arteriovenous malformations, or hereditary hemorrhagic telangiectasia, while intracardiac shunts are often associated with patent foramen ovale or other cardiac defects 1.
- The use of agitated saline contrast is not approved by the US Food and Drug Administration for use in patients with right-to-left shunts, bidirectional shunts, or suspected transient right-to-left shunts, but it can still be useful in many cases, as noted in 1.
Overall, the clinical significance of intrapulmonary shunting with agitated saline contrast lies in its ability to provide valuable diagnostic information for distinguishing between intrapulmonary and intracardiac shunts, which is essential for proper patient management and treatment decisions, as supported by the evidence from 1.
From the Research
Clinical Significance of Intrapulmonary Chanting with Agitated Saline Contrast
- The clinical significance of intrapulmonary chanting with agitated saline contrast is related to the detection of right-to-left shunts, particularly in patients with patent foramen ovale (PFO) 2, 3, 4, 5, 6.
- Agitated saline contrast is used to detect the presence of a right-to-left shunt, which can be a cause of cryptogenic stroke 3, 6.
- The use of agitated saline contrast injection (ASCi) for detecting atrial shunting is well documented, and it is considered a simple and highly accurate method for the detection of right-to-left atrial communication 5.
- The Valsalva maneuver can provoke or enhance right-to-left shunting, and it is often used in conjunction with agitated saline contrast to detect PFO 2, 3, 4, 5, 6.
Detection of Right-to-Left Shunts
- Transthoracic echocardiographic (TTE) ASCi is a highly sensitive and specific method for detecting right-to-left atrial communication 5.
- TTE color flow imaging is too insensitive for PFO screening, and it should not be used as the primary diagnostic tool for detecting PFO 5.
- Transesophageal echocardiography (TEE) can also be used to detect PFO, but it may underestimate shunting in some patients 2.
- Power M-mode transcranial Doppler (TCD) can be used to detect secondary right-to-left circulatory shunt (RLS) in patients undergoing transcatheter closure of PFO 4.
Clinical Implications
- The detection of right-to-left shunts using agitated saline contrast has important clinical implications, particularly in patients with cryptogenic stroke 3, 6.
- The presence of a PFO can increase the risk of paradoxical embolism, and the detection of right-to-left shunting can help to identify patients who may be at risk 2, 3, 4, 5, 6.
- The use of agitated saline contrast can help to guide treatment decisions, such as the closure of PFO, and it can also help to monitor the effectiveness of treatment 4, 5.