Passageway between the atria of the human heart
Not to be confused with ostium secundum or foramen ovale (skull).
Sketch showing foramen ovale in a fetal heart. Red arrow shows blood from the inferior cava traveling to the right atrium and then to the left atrium. HF: right atrium, VF: left atrium. HH and VH: right and left ventricle. The heart still has a common pulmonary vein (LV), instead of four.
Heart of human embryo of about thirty-five days, opened on left side.
DetailsPrecursorSeptum secundumSystemCardiovascular systemIdentifiersMeSHD054085TA98A12.1.01.007TA23967FMA86043Anatomical terminology[edit on Wikidata]
In the fetal heart, the foramen ovale (/fəˈreɪmən oʊˈvæli, -mɛn-, -ˈvɑː-, -ˈveɪ-/[1][2][3]), also foramen Botalli, or the ostium secundum of Born, allows blood to enter the left atrium from the right atrium. It is one of two fetal cardiac shunts, the other being the ductus arteriosus (which allows blood that still escapes to the right ventricle to bypass the pulmonary circulation). Another similar adaptation in the fetus is the ductus venosus. In most individuals, the foramen ovale closes at birth. It later forms the fossa ovalis.
Development
Main article: Interatrial septum § Development
The foramen ovale (from Latin 'oval hole') forms in the late fourth week of gestation, as a small passageway between the septum secundum and the ostium secundum. Initially the atria are separated from one another by the septum primum except for a small opening below the septum, the ostium primum. As the septum primum grows, the ostium primum narrows and eventually closes. Before it does so, bloodflow from the inferior vena cava wears down a portion of the septum primum, forming the ostium secundum. Some embryologists postulate that the ostium secundum may be formed through programmed cell death.[4]
The ostium secundum provides communication between the atria after the ostium primum closes completely. Subsequently, a second wall of tissue, the septum secundum, grows over the ostium secundum in the right atrium. Blood then passes from the right to left atrium only by way of a small passageway in the septum secundum and then through the ostium secundum. This passageway is called the foramen ovale.[citation needed]
Closure
The foramen ovale normally closes at birth. At birth, when the lungs become functional, the pulmonary vascular pressure decreases and the left atrial pressure exceeds that of the right. This forces the septum primum against the septum secundum, functionally closing the foramen ovale. In time the septa eventually fuse, leaving a remnant of the foramen ovale, the fossa ovalis.
Function
A fetus receives oxygen not from its lungs, but from the mother's oxygen-rich blood via the placenta. Oxygenated blood from the placenta travels through the umbilical cord to the right atrium of the fetal heart. As the fetal lungs are non-functional at this time, the blood bypasses them through two cardiac shunts. The first is the foramen ovale (the valve present between them called eustachian valve) which shunts blood from the right atrium to the left atrium. The second is the ductus arteriosus which shunts blood from the pulmonary artery (which, after birth, carries blood from the right side of the heart to the lungs) to the descending aorta.[citation needed]
Clinical significance
Main article: Patent foramen ovale
In about 25% of adults the foramen ovale does not close completely, but remains as a small patent foramen ovale ("PFO").[5] In most of these individuals, the PFO causes no problems and remains undetected throughout life.
PFO has long been studied because of its role in paradoxical embolism (an embolism that travels from the venous side to the arterial side). This may lead to a stroke or transient ischemic attack. Transesophageal echocardiography is considered the most accurate investigation to demonstrate a patent foramen ovale. A patent foramen ovale may also be an incidental finding.
References
- ^ "foramen". Merriam-Webster Dictionary. Retrieved 2016-01-22. "ovale". Merriam-Webster Dictionary. Retrieved 2016-01-22.
- ^ "foramen". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 2020-09-30.
- ^ "foramen". Dictionary.com Unabridged (Online). n.d. Retrieved 2016-01-22.
- ^ Sadler, Thomas W. (2004). Langman's Essential Medical Embryology. Lippincott Williams & Wilkins. ISBN 0-7817-5571-9.
- ^ Homma, S. (2005). "Patent Foramen Ovale and Stroke". Circulation. 112 (7): 1063–1072. doi:10.1161/CIRCULATIONAHA.104.524371. ISSN 0009-7322. PMID 16103257.
- Carlson, Bruce (2004). Human Embryology And Developmental Biology (3rd ed.). Elsevier Mosby. ISBN 0-323-03649-X.
- "Congenital Heart Disorders". Cleveland Clinic.
Retrieved from "//en.wikipedia.org/w/index.php?title=Foramen_ovale_(heart)&oldid=1108037488"
A patent foramen ovale (PFO) is a small opening between the two upper chambers of the heart, the right and the left atrium. Normally, a thin membranous wall made up of two connecting flaps separates these chambers. No blood can flow between them. If a PFO exists, a little blood can flow between the atria through the flaps. This flow is not normal.
The condition is most important because it raises the risk for stroke. Blood clots can travel from the right atrium to the left atrium and out to blood vessels of the body. If the clot blocks a blood vessel in the brain, it can cause a stroke. These clots can also damage other organs such as the heart or the kidneys.
Everyone has a PFO at birth. It is a normal part of the circulation of a fetus. But, in most infants, this small hole naturally closes very soon after birth. But in some cases, it does not. It’s a normal finding in children but not in adults.
What causes patent foramen ovale?
Before birth, a PFO is normal. In the fetus, blood high in oxygen travels from the right atrium, across the hole between the atria, and into the left atrium. From here, the blood higher in oxygen goes out to the lower left part of the heart and out to the rest of the body. After birth, the blood high in oxygen is already in the left atrium. So it doesn't need blood from the right atrium. That's why the foramen ovale normally closes soon after birth. Healthcare providers don't know what causes the hole to stay open (patent) in some people instead of closing up.
Sometimes, PFO occurs along with other heart problems. One such condition is Ebstein anomaly. It's when the valve between the upper and lower chambers on the right side of the heart doesn't close properly. Blood can then flow backward.
What are symptoms of patent foramen ovale?
Most of the time, PFO itself causes no symptoms. Sometimes symptoms do result from the complications of PFO, like stroke.
How is patent foramen ovale diagnosed?
Your healthcare provider will ask about your past health and do a physical exam. He or she will also need tests to help make the diagnosis. These include:
- Transthoracic echocardiography, done on the skin of the chest to see how blood is moving through the heart
- Transesophageal echocardiography to take ultrasound pictures taken from the esophagus
- Multidetector CT, as an another way to view the PFO
- Cardiovascular MRI, as another way to see the PFO
Healthcare providers often pair these tests with a bubble study. In this test, the technician injects saline that has been shaken into a blood vessel. The resulting bubbles can be tracked through the heart with the above imaging tests.
Sometimes, a healthcare provider diagnoses a PFO based on tests that were needed to diagnose some other condition. Other times, the healthcare provider may be looking for a PFO. That might happen, for example, if he or she is looking for possible causes of a stroke.
How is patent foramen ovale treated?
Most PFOs require no treatment. People who have no risk factors for stroke or any history of traveling blood clots usually do not get treatment. Your healthcare provider may want to treat your PFO if you have had problems from these traveling blood clots, like stroke.
In these cases, treatment for PFOs varies. In some cases, your healthcare provider may still choose not to treat the PFO. Other options include:
- Antiplatelet medicines such as aspirin, to help prevent blood clots
- Anticoagulant medicines such as warfarin, to help prevent blood clots
- Closure of the PFO with a catheter-based procedure. A catheter is a long, thin tube inserted through a vessel.
- Closure of the PFO during heart surgery
Ask your healthcare provider what treatment plan is best for you.
What are the complications of patent foramen ovale?
Stroke is the major potential complication of PFO. People who have a PFO are slightly more likely to have a stroke than people who do not. A PFO is more likely to be the cause of stroke in a younger adult because younger people don't have as many risk factors for stroke from other causes. Stroke can cause the following symptoms:
- Numbness or weakness of the leg
- Confusion
- Difficulty seeing out of one eye
- Severe headache
- Loss of coordination
Most strokes do not result from a PFO. Even people who have a PFO often have strokes for other reasons.
A PFO can cause other complications as well. These include:
- Migraine and vascular headache
- Air embolism in scuba divers
- Heart attack (rare)
- Blood clots affecting other organ systems. For example, kidney damage may happen because a clot blocks blood flow to the kidney.
- Fat clot
How to manage patent foramen ovale
In many cases, your healthcare provider may choose not to treat your PFO directly. He or she may make suggestions about how to lower your overall risk for stroke. These might include:
- Eating a healthy diet
- Getting enough exercise and avoiding obesity
- Taking medicines for high blood pressure or high cholesterol, as needed
- Not smoking
- Getting treatment for other health conditions that increase the risk for stroke. An example is atrial fibrillation.
- Avoiding excess alcohol use or illicit drugs
Your healthcare provider might also give you tips to prevent getting blood clots in your legs. For instance, avoid sitting or standing in the same position for a long time. Make sure all your healthcare providers know about your PFO. Be sure to follow your healthcare provider's instructions about medicine and lifestyle.
When should I call my healthcare provider?
See a healthcare provider right away if you are having any symptoms of stroke. These include sudden weakness or numbness, confusion, difficulty seeing out of an eye, or loss of coordination.
Key points about patent foramen ovale
- PFO means that you have a small opening between the right and left atria of the heart. This opening normally closes soon after birth. But in many people, it does not.
- PFO itself usually does not cause any symptoms.
- PFO can occasionally result in complications. The most serious of these is stroke.
- Most people will not need treatment for a PFO.
- Some people receive treatment for PFO, especially if they have had a stroke due to a PFO. Healthcare providers may treat with medicine, procedures, or surgery.
Next steps
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells you.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your provider if you have questions.