Which of the following is a rare defect of the heart in which a single common blood vessel comes out of the heart, instead of the usual two vessels?

1. A

   Patent Ductus Arteriosus

2. B

   Truncus Arteriosus

3. C

   Tetralogy of Fallot

4. D

   Transposition of Great Arteries

Appeared in: DSSSB 13 August 2024

Explanation

• Truncus arteriosus is a congenital heart defect defined by a single arterial trunk emerging from the heart, which then supplies the systemic, pulmonary, and coronary circulations.
• This condition always includes a ventricular septal defect (VSD), allowing blood from both the right and left ventricles to mix in the common trunk.
• The single vessel overrides the VSD, receiving blood from both ventricles.
• It is classified as a cyanotic heart defect because the mixing of oxygenated and deoxygenated blood leads to decreased oxygen saturation in the systemic circulation.

Why Other Options Were Wrong

• Option A: Patent Ductus Arteriosus (PDA) involves the failure of the ductus arteriosus, a connection between the aorta and pulmonary artery, to close after birth. It does not involve a single vessel exiting the heart; both the aorta and pulmonary artery are present as separate vessels.
• Option C: Tetralogy of Fallot is a complex defect consisting of four specific abnormalities. However, it still features two distinct great arteries (aorta and pulmonary artery), not a single common vessel.
• Option D: Transposition of the Great Arteries involves the aorta and pulmonary artery being switched (transposed), arising from the incorrect ventricles. There are still two separate vessels, not a single trunk.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Congenital Heart Defects helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Infants with Truncus Arteriosus often present with signs of heart failure and mild cyanosis within the first few weeks of life as pulmonary vascular resistance drops, leading to excessive pulmonary blood flow.
• Nursing assessment is critical for identifying symptoms like tachypnea, poor feeding, and failure to thrive, which warrant immediate cardiologic evaluation.
• Early surgical repair is essential for survival. The procedure involves closing the VSD and creating a separate pathway from the right ventricle to the pulmonary arteries using a conduit.

How to Approach the Question

• First, identify the key defining feature in the question stem: 'a single common blood vessel comes out of the heart, instead of the usual two vessels'.
• This is a factual recall question that requires knowledge of the definitions of various congenital heart defects.
• Analyze the term 'Truncus Arteriosus'. 'Truncus' is Latin for 'trunk', which directly relates to the concept of a single, common vessel.
• Evaluate the other options based on their definitions. PDA is a persistent connection, TOF involves four defects, and TGA involves switched vessels. None of these match the 'single vessel' description.
• Conclude that Truncus Arteriosus is the only option that describes a single great artery arising from the heart.

Concept Tested & Keywords

• Concept Tested: Congenital Heart Defects
• Stem keywords: rare defect, heart, single common blood vessel, two vessels
• Lead-in keywords: Which of the following
• Negative lead-in flag: false

Question ID

QAbitD5mT8oKNrxmMxFp3m

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 606-608

E6 Obstetrics Williams p. 69-93