Systolic Murmur Over Left Chest (2nd-5th Intercostal Spaces)
A systolic murmur spanning the left 2nd to 5th intercostal spaces most likely represents either aortic stenosis (if loudest at the base with radiation to the carotids) or mitral regurgitation (if loudest at the apex), and echocardiography is indicated for any systolic murmur grade 3/6 or greater to determine the underlying pathology and severity 1.
Differential Diagnosis Based on Location Pattern
The broad distribution across multiple intercostal spaces (2nd-5th) suggests you need to identify where the murmur is loudest:
If Loudest at 2nd-3rd Left Intercostal Space (Base)
- Aortic stenosis is the primary concern
- Look for these additional findings that increase probability of aortic valve disease 1:
- Delayed and diminished carotid upstroke (though may be normal in elderly due to vascular stiffening)
- Single or paradoxically split S2
- Crescendo-decrescendo (diamond-shaped) configuration
- Radiation to the carotid arteries
- Grade 4/6 or louder, late-peaking quality
Critical pitfall: In elderly patients, the murmur may be soft or radiate to the apex rather than carotids, and carotid upstroke may appear normal despite severe stenosis 1. Physical examination cannot reliably distinguish severe from less severe aortic stenosis 2.
If Loudest at 4th-5th Left Intercostal Space (Apex)
- Mitral regurgitation is most likely
- The "broad apical" pattern suggests significant MR 2
- Look for:
- Holosystolic (pansystolic) quality - begins with S1 and continues through S2 1
- Blowing, high-pitched character
- Radiation to the axilla
If Holosystolic Throughout
- Consider ventricular septal defect (though less common in adults)
- Holosystolic murmurs indicate flow between chambers with widely different pressures throughout systole 1
Mandatory Evaluation Steps
Echocardiography is indicated when 1:
- Systolic murmur is grade 3/6 or greater
- Single S2 is present
- Any symptoms potentially attributable to valvular disease
- Uncertain diagnosis on physical examination
The guideline is explicit: echocardiography is often necessary to separate a prominent benign midsystolic murmur from one due to valvular aortic stenosis 1.
Bedside Maneuvers to Refine Diagnosis
Before ordering echocardiography, perform these maneuvers 1:
- Respiration: Left-sided murmurs (AS, MR) are louder during expiration
- Handgrip exercise: Increases afterload
- MR and VSD murmurs become louder
- AS murmur stays the same or decreases
- Valsalva maneuver: Most murmurs decrease
- Exception: Hypertrophic cardiomyopathy becomes much louder
- Standing: Most murmurs diminish
- Exception: Hypertrophic cardiomyopathy and MVP become louder
What Echocardiography Must Assess
Once ordered, echocardiography should evaluate 1:
- Valve morphology and function
- Severity of stenosis or regurgitation using Doppler measurements
- LV size, wall thickness, and systolic function
- Presence of other associated valvular disease (35% have multiple abnormalities 3)
Key Clinical Caveats
Physical examination has significant limitations: Studies show sensitivity is poor for detecting combined aortic and mitral valve disease (55%), aortic regurgitation (21%), and intraventricular pressure gradients (18%) 3
Multiple lesions are common: In 35% of patients with organic heart disease, more than one abnormality is present, with combined aortic and mitral valve disease being most frequent 3
The only reliable physical finding to exclude severe AS is a normally split S2 1
Do not rely on physical examination alone to determine severity or guide management decisions - echocardiography is essential for accurate assessment 2, 3