A nurse posted in a paediatric cardiology unit noted that the assessment findings of an infant reveal a continuous machinery murmur on the auscultation of the heart and signs of heart failure. She identifies that the infant has which of the following congenital cardiac defects?

1. A

   Atrial septal defect

2. B

   Aortic stenosis

3. C

   Ventricular septal defect

4. D

   Patent ductus arteriosus

Appeared in: AIIMS Jodhpur SNO-2023

Explanation

• The hallmark clinical finding for Patent Ductus Arteriosus (PDA) is a continuous 'machinery-like' murmur.
• This murmur is created by the constant flow of blood from the high-pressure aorta to the lower-pressure pulmonary artery through the patent ductus.
• The flow occurs throughout the entire cardiac cycle (systole and diastole), which is why the murmur is described as continuous.
• A large left-to-right shunt through the PDA increases blood flow to the lungs, leading to pulmonary congestion and volume overload, which manifests as signs of heart failure in an infant.

Why Other Options Were Wrong

• Option A: Atrial Septal Defect (ASD) does not cause a continuous machinery murmur.
• Option B: Aortic Stenosis (AS) is characterized by a systolic murmur, not a continuous one.
• Option C: Ventricular Septal Defect (VSD) causes a murmur only during systole (holosystolic).

Related Visual

• Visual 1: Diagram: Anatomy of the heart showing a Patent Ductus Arteriosus connecting the aorta and the pulmonary artery.
• Visual 2: Phonocardiogram: Waveform illustrating a continuous machinery murmur, showing sound throughout both systole and diastole, peaking around the second heart sound (S2).

Clinical Relevance

• Nursing practice connection: Use the key finding related to Diagnosis of congenital heart defects from auscultatory findings to guide bedside assessment, documentation, and the next nursing action.
• Prompt recognition of a machinery murmur is critical for early diagnosis of PDA, allowing for timely intervention to prevent long-term complications like pulmonary hypertension (Eisenmenger syndrome) and heart failure.
• Nursing care for an infant with a significant PDA focuses on managing heart failure symptoms, including strict fluid monitoring, providing high-calorie nutrition for growth, and minimizing oxygen demand.
• What if the infant was premature? In premature infants, medical management with prostaglandin inhibitors like indomethacin or ibuprofen is often the first-line treatment to induce closure of the ductus, as their tissues are more responsive to these medications.

How to Approach the Question

• First, identify the most specific and unusual clinical finding in the question stem, which is the 'continuous machinery murmur'.
• Recognize that specific heart murmurs are classic, 'textbook' signs of particular cardiac defects. This is a knowledge-based recall question.
• Systematically review the options and recall the characteristic murmur associated with each congenital heart defect.
• Match the 'continuous machinery murmur' to its corresponding condition, which is Patent Ductus Arteriosus.
• Use the secondary information ('signs of heart failure') to confirm the diagnosis, as a large, hemodynamically significant PDA is a common cause of heart failure in infancy.

Concept Tested & Keywords

• Concept Tested: Diagnosis of congenital heart defects from auscultatory findings
• Stem keywords: paediatric cardiology, infant, assessment findings, continuous machinery murmur, auscultation, signs of heart failure, congenital cardiac defects
• Lead-in keywords: which of the following
• Clinical cues: 'Continuous machinery murmur' is the pathognomonic sign for Patent Ductus Arteriosus.
• Clinical cues: 'Signs of heart failure' indicate a hemodynamically significant shunt.

Question ID

QM7FBjr1YALjMQ6vlacnjg

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