Cardiovascular System - Atrial Septal Defects

Introduction

Atrial Septal Defect

Atrial Septal Defects (ASD) are a group of common (1% of cardiac) congenital anomolies defects occuring in a number of different forms and more often in females.

• patent foramen ovale- allows a continuation of the atrial shunting of blood, in 25% of people a probe patent foramen ovale (allowing a probe to bepassed from one atria to the other) exists.
• ostium secundum defect
• endocardial cushion defect involving ostium primum
• sinus venosus defect - contributes about 10% of all ASDs and occurs mainly in a common and less common form. Common ("usual type") - in upper atrial septum which is contiguous with the superior vena cava. Less common - at junction of the right atrium and inferior vena cava.
• common atrium

Treatment: The surgical repair requires a cardiopulmonary bypass and is recommended in most cases of ostium secundum ASD, even though there is a significant risk involved. Ostium primum defects tend to present earlier and are often associated with endocardial cushion defects and defective mitral or tricuspid valves. In such cases, valve replacement may be necessary and the extended operation has a considerable chance of mortality.

• Increasingly closure by a transcatheter device closure has been applied.
• Repair of atrial septal defects on the perfused beating heart (atrial septal defect size 2 cm - 4.5 cm)

Some Recent Findings

Spontaneous Closure of Muscular Trabecular Ventricular Septal Defect: Comparison of Defect Positions PMID 21517965 "We performed a historical cohort study for which 150 patients <3 months of age (median age, 9 days) diagnosed as having a muscular trabecular VSD were selected. ...We infer that midventricular muscular trabecular VSD tends to close spontaneously earlier and more frequently than either anterior or apical muscular trabecular VSD."

Cardiovascular Abnormalities

Data shown as a percentage of all major abnormalities based upon published statistics using the same groupings as Congenital Malformations Australia 1981-1992 P. Lancaster and E. Pedisich ISSN 1321-8352.

Heart defects and preterm birth are the most common causes of neonatal and infant death. The long-term development of the heart combined with extensive remodelling and post-natal changes in circulation lead to an abundance of abnormalities associated with this system.

A UK study literature showed that preterm infants have more than twice as many cardiovascular malformations (5.1 / 1000 term infants and 12.5 / 1000 preterm infants) as do infants born at term and that 16% of all infants with cardiovascular malformations are preterm. (0.4% of live births occur at greater than 28 weeks of gestation, 0.9% at 28 to 31 weeks, and 6% at 32 to 36 weeks. Overall, 7.3% of live-born infants are preterm)

"Baltimore-Washington Infant Study data on live-born cases and controls (1981-1989) was reanalyzed for potential environmental and genetic risk-factor associations in complete atrioventricular septal defects AVSD (n = 213), with separate comparisons to the atrial (n = 75) and the ventricular (n = 32) forms of partial AVSD. ...Maternal diabetes constituted a potentially preventable risk factor for the most severe, complete form of AVSD."

In addition, there are in several congenital abnormalities that exist in adults (bicuspid aortic valve, mitral valve prolapse, and partial anomalous pulmonary venous connection) which may not be clinically recognized.

References

Articles

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External Links

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• OMIM Atrial Septal Defect
• Medline Plus ASD Repair Video

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Cite this page: Hill, M.A. (2024, April 26) Embryology Cardiovascular System - Atrial Septal Defects. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_System_-_Atrial_Septal_Defects

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G