Blalock-Taussig Shunt is the surgical management of which of the following congenital heart diseases?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2019

Child Health Nursing (Pediatrics)

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2019

Explanation

Tetralogy of Fallot (TOF) is a cyanotic congenital heart defect characterized by four anomalies, most importantly right ventricular outflow tract obstruction (pulmonary stenosis).
This obstruction limits blood flow to the lungs, causing deoxygenated blood to shunt into the systemic circulation, resulting in cyanosis.
The Blalock-Taussig (BT) shunt is a palliative procedure that creates an artificial connection between the systemic and pulmonary circulations (e.g., subclavian artery to pulmonary artery).
This shunt bypasses the obstruction, increases blood flow to the lungs, improves oxygen saturation, and allows for the growth of pulmonary arteries before a definitive surgical repair.

Option A: Atrial Septal Defect (ASD) is an acyanotic defect that causes a left-to-right shunt, leading to increased pulmonary blood flow. A BT shunt would worsen this pulmonary over-circulation.
Option B: Ventricular Septal Defect (VSD) is also typically an acyanotic defect with increased pulmonary blood flow due to a left-to-right shunt. A BT shunt is contraindicated.
Option D: In Transposition of the Great Arteries (TGA), the primary problem is two separate parallel circulations. The goal is to create mixing of blood, typically via a balloon atrial septostomy, followed by an arterial switch operation. A BT shunt is not the standard primary management.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Surgical management of congenital heart diseases, specifically the indication for a Blalock-Taussig shunt as background academic context rather than a clinical decision trigger.
Nurses play a critical role in the post-operative care of infants with a BT shunt. A key assessment is auscultating for a continuous murmur, which confirms shunt patency. The sudden disappearance of this murmur is a medical emergency indicating shunt thrombosis.
It is a critical patient safety measure to avoid using the arm on the side of the shunt for blood pressure measurements, IV insertions, or arterial punctures to prevent compromising blood flow and causing shunt occlusion.
What if? If a child with a BT shunt suddenly becomes more cyanotic and the continuous murmur disappears, this signifies acute shunt thrombosis. The nurse's immediate actions are to notify the surgical team, prepare for emergency intervention (which may include thrombolytics or return to the operating room), and provide respiratory support.

How to Approach the Question

First, identify the core concept of the question: the purpose of a Blalock-Taussig (BT) shunt.
Recall that a BT shunt is a palliative procedure designed to increase pulmonary blood flow.
Analyze the options based on their pathophysiology. Ask yourself: 'Which of these conditions involves decreased pulmonary blood flow that would be helped by a shunt?'
Eliminate options with increased pulmonary blood flow (ASD, VSD).
Differentiate between the remaining cyanotic heart diseases. TOF is classically defined by pulmonary stenosis causing decreased pulmonary flow. TGA's primary issue is malposition of arteries, not necessarily decreased flow.
Conclude that TOF is the classic indication for a BT shunt among the choices.

Concept Tested & Keywords

Concept Tested: Surgical management of congenital heart diseases, specifically the indication for a Blalock-Taussig shunt.
Stem keywords: Blalock-Taussig Shunt, surgical management, congenital heart diseases
Lead-in keywords: which of the following

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E6 Medicine Davidson Principles Practice 24e p. 557-559

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 pp. 596-598, 598-600