How the Heart Works
Diagram of a Normal Heart
There are several types of heart defects that may involve one or more of the heart’s four chambers. To understand these defects, one must first understand how the heart works.
Generally, blood circulates through the heart and into the body in an endless "figure eight" cycle. One loop carries blood to the lungs to replenish oxygen; the other carries the oxygen-rich blood to the rest of the body.
Prior to birth, however, things work quite differently. While in the womb, a fetus is not yet breathing; it receives oxygenated blood directly from the lungs of its mother. Very little blood is needed in the fetal lungs.
This is where the efficiency of nature takes over. There is a "shortcut" through which the mother's blood is mostly diverted from the lungs and into the body of the fetus.
This "shortcut" usually closes at birth or shortly thereafter. This change accommodates the increasing blood pressure in the infant’s heart as it begins its normal stage of development.
The smooth flow of blood that the heart is now expected to supply is sometimes complicated by Patent Foramen Ovale (PFO). This defect is an opening in the infant's heart that has not closed or sealed properly.
In the 1950's, open-heart surgery was introduced to close these defects. Now, in most patients, there is a simple, less-invasive way to do the same job without surgery – the AMPLATZER device occlusion of heart defects.Copyright © 1997-2003, AGA Medical Corporation, Golden Valley, Minnesota, USA. All rights reserved. All information is sole property of AGA Medical Corporation.
What is a Patent Foramen Ovale (PFO)?
Diagram of a Heart with a PFO defect
In the womb, a fetus is not yet breathing, so it doesn't need much blood flowing through its lungs.
This is where the efficiency of nature takes over. There is a "shortcut" through which the mother's blood is mostly diverted away from the lungs and into the body of the fetus.
The shortcut is called the foramen ovale. It's a small hole between the upper left and upper right chambers, or atria, of the heart. The hole is generally higher up on the wall (septum) between the chambers, just above where a secundum-type Atrial Septum Defect (ASD) would be located.
The foramen ovale should grow closed at birth or shortly afterward. This change accommodates the increasing blood pressure in the aorta and left side of the infant's heart as it begins its normal stage of development.
If the foramen ovale doesn't close, as it should, blood can flow through it from right to left. This condition is referred to as Patent Foramen Ovale (PFO). The word "patent" is a medical term that means "open."
Patent foramen ovale is suspected as a pathway for blood clots which can potentially lead to a stroke or transient ischemic attack (TIA).
If you have suffered a stroke, your neurologist will attempt to locate the source of the embolus. When the source of the clot or embolus cannot be found through diagnostic testing, the stroke may be labeled as "cryptogenic" (unknown source) in nature.
Stroke or TIA that is cryptogenic in nature may lead your neurologist to refer you for ultrasound imaging of your heart. If a Patent Foramen Ovale is found in conjunction with an unknown source of stroke, you may be referred for medical treatment or AMPLATZER device closure of your PFO. The AMPLATZER PFO Occluder is designed to close a PFO that is suspected as a pathway of embolic material with an unknown source.Copyright © 1997-2003, AGA Medical Corporation, Golden Valley, Minnesota, USA. All rights reserved. All information is sole property of AGA Medical Corporation.