What is the purpose of a bubble study (Contryst Desk (Contryst Desk) - contrast ultrasound study) to diagnose patent (patent) right-to-left cardiac shunt or other cardiac abnormalities?

From the Guidelines

A bubble study, also known as a contrast ultrasound study, is a crucial diagnostic tool for detecting patent right-to-left cardiac shunts, such as a patent foramen ovale (PFO), which can increase the risk of stroke, migraines, and low oxygen levels. The study involves injecting a saline solution with tiny bubbles into a vein, typically in the arm, and then using an echocardiogram to visualize the bubbles as they move through the heart chambers 1. If the bubbles appear on the left side of the heart, it indicates an abnormal connection between the heart chambers, such as a PFO. The sensitivity of the bubble study can be increased by asking the patient to perform a Valsalva maneuver, which transiently increases right atrial pressure 1.

Key Points to Consider

• The bubble study is a relatively quick and minimally invasive procedure with a low risk of complications, making it a valuable diagnostic tool for cardiologists 1.
• The study is particularly important for investigating unexplained strokes, migraines, or low oxygen levels, as these conditions can sometimes be linked to right-to-left cardiac shunts 1.
• Patients with a PFO are at a higher risk of stroke, and the bubble study can help identify those who may benefit from PFO closure or other treatments 1.
• The RESPECT trial, a high-quality study published in 2018, reported that PFO closure can reduce the risk of recurrent ischemic stroke in carefully selected patients with a cryptogenic stroke and PFO 1.

Recommendations for Clinical Practice

• The bubble study should be considered a first-line diagnostic tool for detecting patent right-to-left cardiac shunts, such as PFO, in patients with unexplained strokes, migraines, or low oxygen levels.
• Patients with a positive bubble study result should be referred to a cardiologist for further evaluation and consideration of PFO closure or other treatments.
• The bubble study should be performed in accordance with established guidelines and protocols, including the use of a Valsalva maneuver to increase sensitivity 1.

From the Research

Purpose of a Bubble Study

The purpose of a bubble study, also known as a contrast ultrasound study, is to diagnose patent right-to-left cardiac shunt or other cardiac abnormalities, such as patent foramen ovale (PFO) 2, 3, 4, 5, 6.

Detection of Patent Foramen Ovale

A bubble study is typically performed using agitated saline ("bubble study", BS) during echocardiography to demonstrate PFO 2, 3, 4, 6. The study can help identify patients with a PFO, which is a potential mechanism for paradoxical embolism in cryptogenic ischemic stroke or transient ischemic attack (TIA) 2.

Diagnostic Techniques

Techniques and guidelines for the detection and exclusion of a PFO using transthoracic echocardiography with agitated saline microbubbles have been described 3. The study highlights the potential for misinterpretation of bubble studies and discusses several false positive and false negative scenarios.

Clinical Features and Complications

Cerebral ischemic events associated with 'bubble study' for identification of right to left shunts have been reported 5. The events occurred either during or within 5 minutes of the bubble study, and diagnostic evaluation revealed a patent foramen ovale alone or in combination with other cardiac or pulmonary shunts.

Optimization of PFO Detection

Optimization measures such as fluid replenishment with passive leg raise (PLR) can enhance PFO detection during transesophageal echocardiography (TEE) bubble study, particularly in cases where hypovolemia related to preprocedural fasting may challenge detection 6.

Key Findings

• A bubble study is a useful diagnostic tool for detecting PFO and other cardiac abnormalities 2, 3, 4, 5, 6.
• The study can help identify patients with a PFO, which is a potential mechanism for paradoxical embolism in cryptogenic ischemic stroke or TIA 2.
• Techniques and guidelines for the detection and exclusion of a PFO using transthoracic echocardiography with agitated saline microbubbles have been described 3.
• Cerebral ischemic events associated with 'bubble study' for identification of right to left shunts have been reported 5.
• Optimization measures such as fluid replenishment with PLR can enhance PFO detection during TEE bubble study 6.

Some key points to consider when interpreting the results of a bubble study include:

• The presence of a PFO or other cardiac abnormalities 2, 3, 4, 5, 6
• The risk of paradoxical embolism in patients with cryptogenic ischemic stroke or TIA 2
• The potential for misinterpretation of bubble studies and the importance of following guidelines for detection and exclusion of a PFO 3
• The risk of cerebral ischemic events associated with the bubble study 5
• The importance of optimization measures to enhance PFO detection during TEE bubble study 6