Heart Murmurs for PA
Heart Murmurs for the Physician Assistant Licensing Exam
Overview of Heart Murmurs
Heart murmurs are sounds produced by turbulent blood flow across heart valves and can be categorized by their timing in the cardiac cycle. Systolic murmurs occur during ventricular contraction, diastolic murmurs during relaxation, and continuous murmurs throughout the cardiac cycle.
Systolic Murmurs
Aortic Stenosis
- Mechanism: Narrowed aortic valve creates left ventricular (LV) outflow obstruction.
- Auscultation:
- Location: Right upper sternal border, radiating to the carotids.
- Sound: Harsh, crescendo-decrescendo.
- Clinical Significance: Symptoms include exertional dyspnea, angina, and syncope. Severe cases may require valve replacement.
Mitral Regurgitation
- Mechanism: Incomplete closure of the mitral valve causes backflow from the LV to the left atrium.
- Auscultation:
- Location: Apex, radiating to the axilla.
- Sound: High-pitched, holosystolic.
- Clinical Significance: Common causes include mitral valve prolapse (MVP) and LV dilation. Severe cases may necessitate valve repair.
Diastolic Murmurs
Aortic Regurgitation
- Mechanism: Backflow from the aorta into the LV during diastole.
- Auscultation:
- Location: Left sternal border.
- Sound: High-pitched, decrescendo.
- Clinical Significance: Associated with widened pulse pressure and bounding pulses. Severe regurgitation may require valve replacement.
Mitral Stenosis
- Mechanism: Narrowed mitral valve restricts flow from the left atrium to the LV.
- Auscultation:
- Location: Apex, best heard in the left lateral decubitus position.
- Sound: Low-pitched, rumbling murmur with an opening snap.
- Clinical Significance: Often due to rheumatic fever, mitral stenosis can lead to atrial fibrillation and pulmonary hypertension.
Continuous Murmurs
Patent Ductus Arteriosus (PDA)
- Mechanism: Persistent connection between the aorta and pulmonary artery allows continuous flow.
- Auscultation:
- Location: Left infraclavicular area.
- Sound: Continuous, “machinery-like.”
- Clinical Significance: Untreated PDA can cause heart failure and pulmonary hypertension; often treated with NSAIDs in neonates or surgical closure.
Key Points
- Systolic Murmurs:
- Aortic Stenosis: Crescendo-decrescendo murmur at the right upper sternal border, radiating to the carotids.
- Mitral Regurgitation: Holosystolic murmur at the apex, radiating to the axilla.
- Diastolic Murmurs:
- Aortic Regurgitation: High-pitched, decrescendo murmur at the left sternal border.
- Mitral Stenosis: Low-pitched, rumbling murmur at the apex with an opening snap.
- Continuous Murmurs:
- PDA: Continuous “machinery-like” murmur in the left infraclavicular area.
- Clinical Relevance:
- Severe valve disease can lead to heart failure and may require surgical intervention.
- Echocardiography is key for assessing murmur etiology and guiding management.