What causes a swishing sound in the chest?

Swishing Sound in the Chest: Causes and Clinical Significance

Most Likely Diagnosis

A swishing sound in the chest most commonly represents either a cardiac murmur from valvular disease or turbulent blood flow through a narrowed vessel (bruit), though in specific contexts it may indicate Hamman's sign from pneumomediastinum or pneumothorax. 1, 2, 3

Primary Cardiac Causes

Valvular Heart Disease

The most frequent cause of a swishing sound is a cardiac murmur from abnormal blood flow across heart valves:

• Systolic murmurs produce characteristic swishing sounds when blood flows through stenotic or regurgitant valves, with holosystolic murmurs occurring throughout systole in conditions like mitral or tricuspid regurgitation 1
• Midsystolic ejection murmurs create a crescendo-decrescendo swishing pattern when blood ejects across aortic or pulmonic outflow tracts 1
• Continuous murmurs may represent either a cervical venous hum (heard in right supraclavicular fossa, obliterated by chin movement) or mammary souffle (over engorged breast, disappears with firm stethoscope pressure) 1

Distinguishing Features on Examination

• The location of maximum intensity helps identify the valve involved—aortic sounds at second right intercostal space, mitral at apex 1
• Dynamic maneuvers alter murmur intensity: right-sided murmurs increase with inspiration, left-sided with expiration 1
• Associated findings like slow-rising pulse (aortic stenosis), wide pulse pressure (aortic regurgitation), or fixed split S2 (atrial septal defect) provide diagnostic clues 1

Vascular Causes

Bruits

A bruit represents turbulent flow through narrowed vessels and has distinct characteristics:

• Medium-pitched, harsh character heard directly over the affected vessel rather than radiating from the heart 2
• Carotid bruits indicate >50% likelihood of hemodynamically significant stenosis, though positive predictive value is only ~30% 2
• Tracing the sound to its point of maximum intensity differentiates bruits (loudest over vessel) from radiating cardiac sounds (loudest at valve) 2

Life-Threatening Causes Requiring Immediate Recognition

Hamman's Sign (Pneumomediastinum/Pneumothorax)

A loud precordial pulse-synchronous clicking or crunching sound that is often postural:

• Pathognomonic for left-sided pneumothorax or pneumomediastinum when present 3
• Present in only one-fifth of patients with spontaneous pneumomediastinum, making it an insensitive but highly specific finding 4
• The sound results from air in the mediastinum moving with cardiac contractions 3
• Critical pitfall: This rare but diagnostic sign is often missed, leading to unnecessary testing when it could expedite diagnosis 3

Pericardial Friction Rub

• Produces a scratching or swishing sound that increases in the supine position and may be associated with positional chest pain 1
• Indicates pericarditis requiring specific management 1

Diagnostic Algorithm

Step 1: Initial Assessment

Perform focused cardiovascular examination to identify life-threatening causes (ACS, aortic dissection, PE, pneumothorax) 1:

• Check for hemodynamic instability (diaphoresis, tachycardia, hypotension) suggesting ACS 1
• Assess for pulse differentials and sudden severe pain suggesting aortic dissection 1
• Look for unilateral absent breath sounds indicating pneumothorax 1

Step 2: Characterize the Sound

• Timing with cardiac cycle: Systolic vs. diastolic vs. continuous 1
• Location of maximum intensity: Over heart valves vs. over vessels vs. precordial 1, 2
• Postural changes: Does it change with position or respiration? 1, 3
• Quality: Musical/swishing (valvular) vs. harsh (bruit) vs. crunching (Hamman's) 1, 2, 3

Step 3: Dynamic Maneuvers

• Respiratory variation: Right-sided sounds increase with inspiration 1
• Valsalva maneuver: Most murmurs decrease except hypertrophic cardiomyopathy 1
• Position changes: Pericardial rubs worsen supine; Hamman's sign is often postural 1, 3

Step 4: Confirmatory Testing

• ECG within 10 minutes if any concern for cardiac ischemia or pericarditis 1
• Echocardiography for definitive valve assessment and to quantify regurgitation or stenosis 1
• Chest imaging (X-ray or CT) if pneumomediastinum/pneumothorax suspected 3
• Duplex ultrasonography for vascular bruits when clinical differentiation is difficult 2

Critical Pitfalls to Avoid

• Don't dismiss chest sounds in younger patients: Innocent flow murmurs are common but require differentiation from pathologic causes 1
• Don't overlook Hamman's sign: Though rare, it is pathognomonic and prevents unnecessary cardiac workup 3
• Don't rely solely on auscultation for bruits: Low positive predictive value (~30%) necessitates imaging confirmation 2
• Don't assume all continuous sounds are benign: Distinguish between innocent venous hums/mammary souffles and pathologic continuous murmurs (patent ductus arteriosus) 1

Special Populations

Pregnancy

• Soft grade 1-2 midsystolic murmurs are normal findings in pregnancy due to increased cardiac output 1
• Continuous mammary souffles are common in late pregnancy/early puerperium and disappear when standing 1
• Diastolic murmurs remain abnormal even in pregnancy and require evaluation 1