From the Guidelines
A positive bubble study on an echocardiogram in the setting of acute cerebrovascular accident (CVA) indicates the presence of a right-to-left shunt, most commonly a patent foramen ovale (PFO), suggesting a potential paradoxical embolism as the cause of the stroke. This finding is crucial in determining the management of the patient, as it may influence the choice of anticoagulation therapy and the consideration of PFO closure. According to the guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients, RV agitated normal saline contrast should be used in all patients where cardiac source of embolic cerebrovascular accident is suspected to rule out paradoxical emboli 1.
When evaluating a patient with acute CVA and a positive bubble study, anticoagulation therapy is typically recommended, with options including direct oral anticoagulants (DOACs) like apixaban 5mg twice daily or rivaroxaban 20mg daily, or warfarin with a target INR of 2-3. The presence of a PFO in patients with a massive PE increases the risk of death, ischemic stroke, peripheral arterial embolism, and a complicated hospital course 1. For patients with recurrent strokes despite medical therapy or those with large shunts, PFO closure may be considered, as this mechanical intervention has shown benefit in reducing recurrent stroke risk in carefully selected patients under 60 years old with cryptogenic stroke.
The management decision should be individualized based on the patient's age, comorbidities, stroke characteristics, and size of the shunt, ideally through a multidisciplinary discussion involving neurology and cardiology. Key considerations include:
- The patient's overall clinical condition and risk factors for stroke
- The size and location of the PFO
- The presence of other potential stroke causes
- The patient's ability to tolerate anticoagulation therapy or PFO closure
- The potential benefits and risks of each treatment option, including the risk of recurrent stroke, bleeding, and procedural complications.
From the Research
Positive Bubble Study Indications
A positive bubble study on echocardiogram (echo) indicates the presence of a right-to-left shunt (RLS), which can be a potential mechanism for paradoxical embolism in cryptogenic ischemic stroke or transient ischemic attack (TIA) 2. This is often associated with a patent foramen ovale (PFO), a condition where there is an opening between the upper chambers of the heart that did not close after birth.
Clinical Implications
The detection of a PFO through a bubble study can have significant clinical implications, particularly in patients with acute cerebrovascular accident (CVA) 3, 4. A positive bubble study may suggest that the patient is at risk of paradoxical embolism, where a blood clot forms in the veins, passes through the PFO, and travels to the brain, causing a stroke.
Diagnostic Techniques
Transcranial Doppler with bubble study (TCD-b) is a useful technique for detecting extracardiac right-to-left shunts in patients with ischemic stroke 5. This technique can help identify patients who may benefit from further evaluation and treatment, such as percutaneous PFO closure. Transesophageal echocardiography (TEE) is also a valuable tool for diagnosing PFO and detecting RLS 6.
Key Findings
- A positive bubble study indicates the presence of a RLS, which can be a potential mechanism for paradoxical embolism in cryptogenic ischemic stroke or TIA 2.
- PFO is an independent risk factor for cerebral infarction, and the detection of a PFO through a bubble study can have significant clinical implications 4.
- TCD-b is a useful technique for detecting extracardiac right-to-left shunts in patients with ischemic stroke 5.
- The combination of TEE and TCD-b can provide a comprehensive evaluation of RLS and PFO, aiding in the prevention of paradoxical embolism 6.