Pediatric Patent Foramen Ovale Atrial Septal Defects Workup

Updated: Sep 16, 2019
  • Author: Barry A Love, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Workup

Laboratory Studies

No laboratory tests are specific for patent foramen ovale (PFO).

In patients with a cryptogenic stroke and a patent foramen ovale, a complete hypercoagulable workup is indicated to rule out a hypercoagulable state. If a hypercoagulable condition is found, specific treatment of this condition with antiplatelet therapy or anticoagulation may be indicated. Consultation with a hematologist should be considered for patients in whom a hypercoagulable state is suspected. Closure of the patent foramen ovale may be indicated in patients with a hypercoagulable state, although one needs to be aware that surgical closure should be considered because the risk of thrombosis on transcatheter occlusion devices may be increased in the presence of a hypercoagulable state.

A hypercoagulable workup typically consists of the following tests:

  • CBC count (for platelet count)

  • Prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR)

  • Factor V Leiden assessment

  • Prothrombin gene mutation

  • Protein C and protein S assessment (Note that proteins C and S are vitamin K–dependent factors and should not be measured while the patient is taking warfarin [Coumadin]).

  • Antithrombin III assessment

  • Homocysteine assessment

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Imaging Studies

Transthoracic 2-dimensional echocardiography

Transthoracic 2-dimensional echocardiography can generally image the atrial septum and show the flap of the foramen ovale in infants and small children. Color Doppler flow across the atrial septum proves the presence of the foramen ovale. A foramen ovale may be differentiated from an atrial septal defect by the overlap of septal tissue. In older children and adults, transthoracic echocardiography does not visualize the atrial septum as well.

Transesophageal echocardiography

Transesophageal echocardiography (TEE) is preferred in patients where the atrial septum is inadequately visualized by transthoracic echocardiography. Older children and adults fall into this category. In addition to the patent foramen ovale, redundancy of septum primum can also be seen. When the redundancy of the septum moves more than 1 cm, it is called an atrial septal aneurysm. In the presence of a patent foramen ovale in patients who have had a prior stroke, atrial septal aneurysm confers an increased risk for a subsequent neurologic event. [10]

Bubble-contrast echocardiography

Bubble-contrast echocardiography is mandatory to diagnose a patent foramen ovale and to demonstrate a potential right-to-left shunt.

A bubble-contrast study is performed by inserting a peripheral intravenous line and agitating 8 mL of saline with 1 mL of the patient's blood and 1 mL of air. The air is agitated into the solution and the bubble contrast is injected. The atrial septum and left atrium are visualized during the injections. In the presence of a patent foramen ovale, bubbles can be seen crossing the atrial septum and entering the left atrium.

Transesophageal echocardiogram showing the atrial Transesophageal echocardiogram showing the atrial septum. The "flap" of the septum primum is seen. The diagnosis of patent foramen ovale (PFO) cannot be made until right-to-left bubble contrast is demonstrated. LA = Left atrium; RA = Right atrium.

The bubble-contrast injection should be performed at rest and with a Valsalva maneuver. The Valsalva maneuver transiently increases right atrial pressure above left atrial pressure, encouraging potential right-to-left shunting.

Bubble-contrast injection during Valsalva maneuver Bubble-contrast injection during Valsalva maneuver. The "flap" of the foramen ovale is opened and bubbles are seen crossing from the right atrium to the left atrium (arrow).

TEE is usually the best echocardiographic imaging tool to use with a bubble-contrast injection, although it can be performed using transthoracic echocardiography. The sensitivity of transthoracic echocardiography with bubble-contrast injection is poor compared with transesophageal imaging.

Khan et al reviewed the relationship of a patent foramen ovale (PFO) with stroke and evaluated associated comorbidities. They performed an electronic database literature search of PubMed, Cochrane, and EMBASE from January 2000 to December 2014, and they used 65 reports for the comprehensive review. They found that the concurrent use of transthoracic echocardiography with color Doppler and a bubble contrast study is excellent for visualization of the atrial septum and PFO and for identification of a right-to-left shunt. [11]

Transcranial Doppler imaging with bubble-contrast injection

Transcranial Doppler imaging with bubble-contrast injection is a useful screening tool for right-to-left shunting via a patent foramen ovale (see image and video below). An ultrasound probe is placed on the head, and the ultrasound beam is used to sample the middle cerebral arteries. A bubble-contrast injection is performed at rest and with the Valsalva maneuver. Any right-to-left shunt is revealed by the appearance of bubble artifacts on the transcranial Doppler signal. The number of bubble counts correlates with the potential for right-to-left shunting. Modern transcranial Doppler with bubble-contrast injection is as sensitive as TEE with bubble-contrast injection in identifying a patent foramen ovale. [12]

Transcranial Doppler (TCD) study with bubble-contr Transcranial Doppler (TCD) study with bubble-contrast study. A Doppler probe is used to interrogate the right middle cerebral artery. Frame 1 shows normal findings. Note the absence of bubble artifact of Doppler signal in the middle cerebral artery. Frame 2 shows strongly positive (5/5) bubble transit seen in a patient with a patent foramen ovale (PFO) during Valsalva maneuver. TCD is a useful screening tool for PFO because of its ease-of-use and ability to easily quantify the amount of potential right-to-left shunt. One of the pitfalls is the inability to differentiate between other sources of right-to-left shunt, such as pulmonary arteriovenous malformation and a PFO.
Transesophageal echocardiogram of bubble contrast study showing right-to-left passage of bubble-contrast with a Valsalva maneuver. RA = Right atrium. LA = Left atrium. Arrow shows bubble passage to LA.
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