Q1
What is a patent foramen ovale?
Foramen ovale , a structure between the left and right atria in the heart, is called the foramen ovale because of its oval shape. It does not close during fetal life because blood has to flow through this hole. After birth, as the newborn's lungs begin to work, the foramen ovale completes its mission and begins to slowly close. When the baby is about six months to one year old, the foramen ovale will close. However, in about a quarter of people, the foramen ovale cannot be completely closed, leaving gaps of varying sizes, like door curtains, between the left and right atria. This condition is called patent foramen ovale (patent foramen ovale, PFO).
Q2
What are the symptoms of patent foramen ovale?
PFO is usually asymptomatic, but if the patent is severe, the clinical manifestations are diverse. Unexplained stroke and migraine are the most common. A few may experience transient ischemic attack (TIA), recumbent breathing-orthostatic syndrome. Hypoxemia, unexplained dizziness and syncope, vertigo, decompression sickness, epilepsy, and rarely non-atherosclerotic myocardial infarction.
In patients with unexplained embolic stroke, the detection rate of PFO is as high as 40%.
Existing research results show that migraine is related to PFO, especially migraine with aura (there is an aura sensory signal before each attack, common flash hallucinations and other visual defects). The detection rate of PFO in patients with migraine with aura is 40%- 60%. Especially among patients aged 55 and without hypertension or diabetes and other risk factors for atherosclerotic cardiovascular disease, sudden stroke should be investigated to see if it is caused by PFO. About 40%-50% of cases have been proven to be related to patent foramen ovale.
Q3
How is the patent foramen ovale formed?
During embryonic development, the two intervals between the atria gradually grow relative to each other to separate the two atria, but they are not completely adhered and fused. Because blood needs to flow through this hole, a small gap will be left, which is called the foramen ovale. .
After birth, as the newborn's lungs begin to work, under normal circumstances the left atrium pressure is 3-5mmHg higher than the right atrium pressure, the PFO is in a closed state, and there is no inter-atrial blood shunt. The foramen ovale has completed its mission and begins to slowly fuse.
However, under certain circumstances, such as coughing, laughing, sneezing, or Valsalva maneuvers, the right atrial pressure may temporarily increase and exceed the left atrial pressure, causing the weak septum primum on the left side to be pushed open, resulting in right atrial pressure. Left shunt (RLS).
Q4
How to diagnose patent foramen ovale?
When patients suffer from unexplained stroke, peripheral arterial embolism or difficult-to-relieve migraine, or recumbent breathing-orthostatic hypoxemia, the presence of PFO lesions should be considered and ultrasonography examination should be performed.
PFO is commonly diagnosed clinically by echocardiography, including transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and transcranial Doppler contrast-enhanced echocardiography (cTCD).
Conventional transthoracic echocardiography (TTE) has low sensitivity for detecting PFO. Once PFO is suspected, transthoracic echocardiography (cTTE), that is, the foaming test, can be performed, and the sensitivity can reach 63% to 100%.
TEE is the "gold standard" and preferred method for diagnosing PFO. TEE can accurately measure PFO size and morphological characteristics to guide the selection of occluder, and can detect other causes of stroke, such as aortic atherosclerosis. Sclerosis , left atrial hanging thrombosis , etc. Performing TEE examination when PFO is highly suspected may reduce the missed diagnosis rate of TTE. However, TEE also has its own shortcomings, such as the patient's pain and poor compliance when inserting the ultrasound probe from the esophagus, difficulty in completing the standard Valsalva maneuver in the left lateral position during contrast-enhanced ultrasound, and inaccurate evaluation of right-to-left shunts.
The detection rate of transcranial Doppler ultrasound bubble test method (cTCD) is also quite high, with reaching more than 95%.Before the foaming test, it is necessary to prepare activated saline. Inject saline intravenously at rest to observe whether the left heart develops and develops after microbubble development in the right heart. Then instruct the patient to perform the Valsalva maneuver and observe whether there are microbubbles in the left heart when exhaling. Development can more accurately assess the degree of RLS.
Q5
How to treat patent foramen ovale?
PFO treatment should be individualized assessment and treatment based on the level of risk factors, mainly including drug treatment and interventional treatment.
PFO drug treatment is mainly antithrombotic therapy. There is no clear conclusion as to whether aspirin is better than , warfarin, and . There is currently no evidence and experience with new oral anticoagulants for the treatment and prevention of PFO patients.
The current treatment methods for patent foramen ovale include surgical repair of the foramen ovale and transcatheter closure. However, traditional surgical repair in the past has basically been replaced by PFO percutaneous closure. Percutaneous PFO closure is a safe and economical interventional treatment that uses a special closure device to block RLS.
The above content is taken from the Internet. I would like to express my gratitude to the original author!
