Atrial septal defect anatomy: Difference between revisions
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==Anatomy== | ==Anatomy== | ||
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Image:Gray468.png|Heart of human [[embryo]] of about thirty-five days | |||
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The development of [[heart]] in fetal life takes place as early as '''4th week of gestation'''. An abnormal septal development at this stage may lead to [[atrial septal defect]]. The sequence of changes that happen during normal septal embryogenesis in heart development are as follow- | The development of [[heart]] in fetal life takes place as early as '''4th week of gestation'''. An abnormal septal development at this stage may lead to [[atrial septal defect]]. The sequence of changes that happen during normal septal embryogenesis in heart development are as follow- | ||
Revision as of 15:30, 19 August 2011
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [[2]]; Cafer Zorkun, M.D., Ph.D. [3]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [[4]]
Overview
The embryological development of human fetal heart takes place as early as 4th week of intrauterine life. The normal septal development requires a proper alignment and fusion of the two interatrial septums i.e. septum primum and septum secundum. Failure to do so may leads to the development of atrial septal defects.
Anatomy
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Heart of human embryo of about thirty-five days
The development of heart in fetal life takes place as early as 4th week of gestation. An abnormal septal development at this stage may lead to atrial septal defect. The sequence of changes that happen during normal septal embryogenesis in heart development are as follow-
- The developing heart has an orifice called ostium primum between the atrium.
- A septum primum arises from the superior portion of the common atrium of the developing heart.
- An endocardial cushion is located between the atria and ventricles
- Septum primum grows downward to the endocardial cushions. This leads to the closing of the orifice (ostium primum) between the atria.
- A second orifice (the ostium secundum) develops in the septum primum. This second orifice gets covered with septum secundum. However, the septum secundum doesn’t close the ostium secundum completely and this leads to an orifice called the foramen ovale
- In the fetus this orifice allows shunting of blood from right to left side of the heart. This is so because during the fetal life right side heart pressures are more than the systemic pressure. However, there is a reversal of pressure gradient after birth (systemic pressures becomes more than right sided pressure) and this change of pressure causes the septum primum to be held against the septum secundum and closing the interatrial shunt.
- In approximately 30% of population the septum primum and secundum fails to fuse leading to patent foramen ovale (PFO) in the newborn. The patent foramen ovale can be of two types –
- Completely covered but not completely sealed so that the foramen can be opened with reversal of shunt. This is also sometimes called as a probe patent or patent foramen ovale (PFO)
- An open communication exists between right and left atrium persists which is then called an atrial septal defect (ASD).