A nurse is performing a cardiac assessment on a 2-year-old. The first heart sound (S1) can best be heard at which location?

Heart murmurs are extra sounds, like whooshing or swishing, heard during a heartbeat, caused by turbulent blood flow through the heart or its valves. They can be harmless (“innocent”) or signal underlying heart problems such as valve defects or congenital heart disease. Heart murmurs are graded on a scale from 1 to 6 based on their loudness, audibility, and associated physical findings.

Rationale for correct answer:

B. A grade 1 murmur is very faint, requiring focused auscultation. It is softer than the normal S1 and S2 sounds. Often, these murmurs are innocent or functional and not indicative of significant heart disease.

Rationale for incorrect answers:

A. A murmur that is equal to the heart sounds describes a grade 3 murmur, not grade A. Grade 1 is softer, not equal in intensity.

C. This describes grade 6 murmurs which can be heard with the naked ear.

D. A precordial thrill indicates a grade 4 or higher murmur, which is louder and more significant than grade A.

Test-taking strategy:

• Recall the Levine scale for murmur grading:
  • Grade 1: Barely audible; softer than the normal heart sounds; heard only with careful auscultation in a quiet room.
  • Grade 2: Soft but easily heard immediately.
  • Grade 3: Loud murmur, comparable to heart sounds.
  • Grade 4: Loud murmur with a palpable thrill.
  • Grade 5: Very loud, heard with stethoscope partially off the chest, with thrill.
  • Grade 6: Extremely loud, heard with stethoscope off the chest, with thrill.
• Focus on descriptive words like “soft,” “faint,” or “palpable thrill” to differentiate grades.

Take home points

• Grade 1 murmur is very faint, softer than heart sounds, requires careful auscultation.
• Murmur grading helps determine clinical significance and guides further evaluation.
• Thrills and loud murmurs suggest more severe cardiac pathology, while grade 1 murmurs are often innocent in children.

Cardiac assessment is a systematic evaluation of the heart and circulation that combines history-taking, physical examination, and diagnostic techniques to identify cardiovascular health, risks, or disease. It focuses on vital signs, inspection, palpation, auscultation, and sometimes point-of-care imaging to detect abnormalities in heart function and blood flow.

Rationale for correct answer:

D. Fifth intercostal space, left midclavicular line: The first heart sound (S1) is produced by the closure of the atrioventricular (AV) valves, the mitral and tricuspid valves, at the beginning of ventricular systole. S1 is loudest at the apical area. In clinical testing, the apex is classically identified as the 5th intercostal space at the left midclavicular line, which is considered the standard landmark for auscultating SA. The diaphragm of the stethoscope is preferred because S1 is a high-pitched sound.

Rationale for incorrect answers:

A. Third or fourth intercostal space: These locations are closer to the base of the heart, where S2, the closure of aortic and pulmonic valves is louder than SA.

B. The apex with the stethoscope bell: Using the bell is better for low-pitched sounds, like S3 or S4, not the high-pitched SA.

C. Second intercostal space, midclavicular line: The second intercostal space corresponds to the aortic and pulmonic areas, where S2 is best heard, not SA.

Test-taking strategy:

• For heart sounds, exams often prefer precise anatomical landmarks over general descriptions.
• Remember S1 is caused by AV valve closure (mitral/tricuspid) best heard at the apex of the heart.
• Remember S2 is caused by semilunar valve closure (aortic/pulmonic).
• Use the diaphragm for high-pitched sounds (S1, S2), and bell for low-pitched sounds (S3, S4, murmurs).

Take home points

• S1 results from mitral and tricuspid valve closure and is best at apex (5th ICS, left midclavicular line).
• S2 is caused by aortic and pulmonic valve closure and is best at base (2nd ICS, right and left).
• Correct auscultation location is essential for identifying murmurs, rhythm abnormalities, and cardiac function in children.