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Questions and Answers
What is the most common defect diagnosed in adults due to a lower likelihood of spontaneous closure?
What is the most common defect diagnosed in adults due to a lower likelihood of spontaneous closure?
- Patent ductus arteriosus (PDA)
- Coarctation of the aorta
- Atrial septal defects (ASDs) (correct)
- Ventricular septal defects (VSDs)
What is a significant hemodynamic consequence of atrial septal defects (ASDs)?
What is a significant hemodynamic consequence of atrial septal defects (ASDs)?
- Increased systemic vascular resistance
- Decreased pulmonary flow volume
- Left-to-right shunt (correct)
- Right-to-left shunt
Why is there often a murmur present in patients with atrial septal defects (ASDs)?
Why is there often a murmur present in patients with atrial septal defects (ASDs)?
- Excessive flow through the pulmonary valve and/or ASD (correct)
- Stenosis of the mitral valve
- Increased flow through the aorta
- Decreased left ventricular output
What is typically the age at which symptoms from atrial septal defects (ASDs) begin to manifest?
What is typically the age at which symptoms from atrial septal defects (ASDs) begin to manifest?
What is one of the main reasons for performing surgical or intravascular closure of atrial septal defects?
What is one of the main reasons for performing surgical or intravascular closure of atrial septal defects?
What is the primary cause of atrial septal defects (ASDs)?
What is the primary cause of atrial septal defects (ASDs)?
Which opening is present during early fetal development allowing blood movement from the right to the left atrium?
Which opening is present during early fetal development allowing blood movement from the right to the left atrium?
What is the most common type of atrial septal defect?
What is the most common type of atrial septal defect?
What happens to the foramen ovale at birth?
What happens to the foramen ovale at birth?
What is the relationship between the pressure in the atria before and after birth?
What is the relationship between the pressure in the atria before and after birth?
Which type of ASD is often associated with anomalies of the AV valves?
Which type of ASD is often associated with anomalies of the AV valves?
How does the septum secundum contribute to fetal circulation?
How does the septum secundum contribute to fetal circulation?
What clinical feature is commonly associated with ASDs in infants?
What clinical feature is commonly associated with ASDs in infants?
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Study Notes
Atrial Septal Defect (ASD) Overview
- ASDs are fixed openings in the atrial septum, resulting from incomplete tissue formation, permitting blood flow between the left and right atria.
- Often asymptomatic until adulthood.
Developmental Stages of the Atrial Septum
- Septum Primum: Crescent-shaped membranous structure; sits posteriorly, partially separating atria; contains an anterior opening (ostium primum) for early fetal blood movement.
- Ostium Secundum: A second opening develops in the septum primum before it fully closes the ostium primum.
- Septum Secundum: Membranous ingrowth located right and anterior to the septum primum; covers ostium secundum, leaving the foramen ovale for right-to-left blood shunting during fetal life.
- Foramen ovale operates based on pressure gradients between left and right atria, remaining open when right atrial pressure is higher.
Physiological Changes at Birth
- At birth, lung expansion decreases pulmonary vascular pressures; right atrial pressures become lower than left atrial pressures.
- The foramen ovale closes due to this pressure change and usually seals before adulthood.
Morphology of ASDs
- Classified based on location:
- Secundum ASD (90%): Deficient septum secundum near the atrial septum's center; often not associated with other anomalies.
- Primum ASD (5%): Adjacent to AV valves; commonly linked with AV valve defects and/or ventricular septal defects (VSD).
- Sinus Venosus Defect (5%): Near the superior vena cava entrance; may accompany anomalous pulmonary venous return to the right atrium.
Clinical Features
- Many ASDs remain asymptomatic until adulthood; are more frequently diagnosed compared to other defects due to lower spontaneous closure rates.
- ASDs cause left-to-right shunting because of lower pulmonary vascular resistance and greater right ventricle compliance; pulmonary flow can be 2 to 8 times normal.
- A characteristic murmur may be heard due to increased flow through the pulmonary valve and ASD.
- Generally tolerated well; symptoms rarely present before age 30, and irreversible pulmonary hypertension is uncommon.
Treatment and Prognosis
- Surgical or intravascular closure recommended to prevent heart failure, paradoxical embolization, and permanent pulmonary vascular disease.
- Low mortality rates; postoperative outlook similar to healthy population.
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