Difference Between PFO and ASD

The key difference between PFO and ASD is that the PFO is a heart defect that occurs due to the failure of closing the foramen ovale after birth, while the ASD is a heart defect in which blood flows between the right atria and left atria of the heart due to a failure of forming the septal tissue correctly.

Atrial Septal Defect (ASD) and Patent Foramen Ovale (PFO) are two heart defects. Both occur due to a hole in the septum between the two upper chambers: left atrium and right atrium. In ASD, blood flows between the right and left atria. Patent foramen ovale occurs due to a failure in closing the foramen ovale after birth. During high blood pressure, oxygenated blood flows from left atrium to right atrium via the foramen ovale.

CONTENTS

1. Overview and Key Difference
2. What is PFO
3. What is ASD
4. Similarities Between PFO and ASD
5. Side by Side Comparison – PFO vs ASD in Tabular Form
6. Summary

What is PFO?

Foramen ovale is a hole located between the two upper chambers in every growing baby’s heart. It helps oxygenated blood to go from the veins to the right side of the fetus’ heart, and then directly to the left side of the heart. The process is necessary since the lungs of the fetus are not functional when it is inside the uterus. After childbirth, this foramen ovale closes naturally in approximately 75% of peoples. But, in 25% of peoples, it remains open. Thus, this is the condition called PFO or Patent Foramen Ovale. However, foramen ovale does not remain open all the time. In certain situations when the pressure is high in the heart due to some actions such as straining during bowel movements, coughing and sneezing, etc., blood flows from left atrium to right atrium through this flap-like foramen ovale.

Figure 01: PFO and Other Congenital Heart Defects

Due to PFO, certain complications such as migraine, heart attacks, strokes and transient ischemic attack, etc. may occur.

What is ASD?

ASD or Atrial Septal Defect is a congenital heart defect that occurs when the septal tissue doesn’t form correctly between the two atria: right and left atria. In other words, ASD is a heart defect defined as a hole in the interatrial septum. The size of this hole can vary in size. Based on that, the severity of the disease varies. Due to ASD, blood travels from left atrium to right atrium or vice versa and mix oxygenated and deoxygenated blood with each other.

Figure 02: ASD

There are many different types of ASD, such as secundum, primum and senus venosus. ASDs can give rise to certain health conditions such as right heart failure, atrial arrhythmias, strokes, pulmonary hypertension, etc.

What are the Similarities Between PFO and ASD?

• PFO and ASD are two types of heart defects due to holes in the heart.
• Both are holes in the wall of tissue between the left and right upper chambers of the heart, called the septum.
• Due to these holes, oxygenated blood flows from left atrium to right atrium.
• Moreover, strokes and heart attacks are associated with ASD and PFO.

What is the Difference Between PFO and ASD?

PFO is a heart defect that occurs due to the failure of closing foramen ovale after birth. On the other hand, ASD is another heart defect that occurs due to the incorrect formation of septum tissue between the two atria. So, this is the key difference between PFO and ASD.

Moreover, the size of the PFO hole is smaller than the hole of ASD. Besides, the ASD hole can vary in size. Based on that, the severity of the ASD may vary. Hence, we can consider this too as a difference between PFO and ASD.

Summary – PFO vs ASD

PFO and ASD are congenital heart defects. PFO occurs as a result of the failure in closing the foramen ovale after birth. Meanwhile, ASD occurs as a result of the improper formation of septum tissues between two atria. Therefore, this is the key difference between PFO and ASD. In both cases, there is a hole between the right and left atria. But, the size of the ASD hole can vary, and it is larger than the hole size of PFO.

Reference:

1. “Patent Foramen Ovale (PFO).” Cleveland Clinic, Available here.
2. “Atrial Septal Defect.” Wikipedia, Wikimedia Foundation, 30 June 2019, Available here.

Image Courtesy:

1. “2009 Congenital Heart Defects” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
2. By Centers for Disease Control and Prevention – Centers for Disease Control and Prevention (CC0) via Commons Wikimedia

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