What is cardiac wheeze, how can it be distinguished from asthma, and what is the recommended acute evaluation and management?

Cardiac Wheeze: Definition, Differentiation, and Management

What is Cardiac Wheeze?

Cardiac wheeze (also called "cardiac asthma") is expiratory wheezing caused by congestive heart failure and pulmonary venous hypertension, not by primary bronchospasm. 1 It results from reflex bronchoconstriction triggered by cardiogenic pulmonary edema and vascular congestion in the airways. 1, 2

• The term describes wheezing, coughing, and orthopnea due to left-heart backward failure with pulmonary congestion. 1, 2
• Fine rales are typically audible over lung fields, and chest X-ray shows pulmonary congestion/edema. 1
• Cardiac wheeze represents approximately one-third of heart failure presentations in elderly patients. 3

Key Clinical Distinctions from Asthma

History and Risk Factors

The most critical distinguishing features are cardiac risk factors, orthopnea, and lack of typical asthma triggers. 1

• Cardiac wheeze patients have cardiovascular disease history (hypertension, coronary disease, valvular disease) rather than atopy, allergic rhinitis, or eczema. 1, 4
• Symptoms worsen when lying flat (orthopnea) and improve when sitting upright—this is highly specific for cardiac causes. 1, 2
• Asthma characteristically worsens with exercise, allergens, cold air, and at night, with polyphonic wheezing that varies over time. 4, 5
• Cardiac asthma patients more commonly have tobacco use (59% vs 34%), COPD history (47% vs 16%), and peripheral arterial disease (24% vs 10%). 3

Physical Examination Findings

Look for distended neck veins, peripheral edema, S3 gallop, and fine rales—these point to cardiac causes. 1

• Cardiac wheeze presents with pallor or cyanosis, cold clammy skin, and fine rales throughout lung fields. 1
• Expiratory wheezing occurs alongside cardiovascular signs: elevated jugular venous pressure, displaced apex beat, muffled heart sounds, and cardiac murmurs. 1
• Asthma typically shows only respiratory findings without cardiovascular congestion signs. 4, 5

Laboratory and Imaging

B-natriuretic peptide (BNP) measurement is the single most useful test to distinguish cardiac from pulmonary dyspnea. 1

• Elevated BNP confirms heart failure as the cause of wheezing. 1
• Echocardiography demonstrates left ventricular dysfunction, valvular abnormalities, or diastolic dysfunction. 1
• Chest X-ray in cardiac wheeze shows pulmonary congestion/edema, cardiomegaly, and pleural effusions. 1
• Arterial blood gas in cardiac asthma shows lower pH (7.38 vs 7.43) and higher PaCO2 (47 vs 41 mmHg) compared to typical CHF without wheeze. 3

Spirometry Patterns

• Cardiac asthma patients demonstrate distal airway obstruction with FEV1 averaging 1.09L and reduced FEF25-75%. 3
• However, spirometry cannot reliably distinguish cardiac from bronchial asthma when both conditions coexist. 2, 3

Response to Treatment

Poor response to diuretics alone and limited effectiveness of bronchodilators/corticosteroids suggest cardiac wheeze. 2

• Classical asthma medications provide minimal benefit in pure cardiac wheeze. 2
• Cardiac wheeze improves primarily with vasodilators, diuretics, and treatment of underlying heart failure. 1

Acute Evaluation Algorithm

Immediate Assessment

1. Check vital signs: Tachycardia (>100 bpm), tachypnea (25-28/min), blood pressure (may be elevated), and oxygen saturation. 1, 6

2. Examine for cardiac signs: Jugular venous distension, peripheral edema, S3 gallop, displaced apex beat, and fine rales. 1

3. Obtain BNP or NT-proBNP immediately—this is the most discriminating test. 1

4. Order chest X-ray to assess for pulmonary edema, cardiomegaly, and pleural effusions. 1

5. Perform ECG to identify acute ischemia, arrhythmias, or left ventricular hypertrophy. 1

6. Obtain arterial blood gas if respiratory distress is severe—expect lower pH and higher PaCO2 in cardiac asthma. 3

Diagnostic Pitfalls

Never assume wheezing in a critically ill patient reflects a single etiology; combined conditions (heart failure plus COPD, pneumonia plus CHF) commonly coexist. 7

• The presence of moist rales, prolonged expiration, and copious secretions with wheezing demands evaluation for multiple concurrent mechanisms. 7
• Idiopathic pulmonary arterial hypertension can masquerade as asthma with wheezing and airway obstruction. 1
• Severe airflow obstruction may present as a "silent chest" with minimal audible wheeze—absence of wheeze does not exclude severe disease. 7, 8

Acute Management

Primary Treatment for Cardiac Wheeze

Vasodilators are first-line therapy, supplemented by diuretics, respiratory support, and narcotics as needed. 1

• Vasodilators (nitroglycerin, nitroprusside) reduce preload and afterload, improving cardiac output. 1
• Diuretics (furosemide) reduce pulmonary congestion; consider adding spironolactone for right heart involvement. 1
• Bronchodilators may provide modest symptomatic relief but do not address the underlying cardiac pathology. 1, 2
• Morphine reduces anxiety, decreases sympathetic drive, and causes venodilation. 1

Respiratory Support

Non-invasive positive pressure ventilation (CPAP or BiPAP) is preferred over intubation when possible. 1

• Continuous positive airway pressure (CPAP) reduces preload, improves oxygenation, and decreases work of breathing. 1
• Non-invasive positive pressure ventilation avoids complications of intubation. 1
• Invasive ventilation with endotracheal intubation is reserved for severe respiratory failure unresponsive to non-invasive support. 1

Treat Underlying Cardiac Pathology

• Acute coronary syndrome: Revascularization for stunned or hibernating myocardium can restore function. 1
• Valvular disease: Urgent valve repair/replacement for acute mitral or aortic insufficiency. 1
• Arrhythmias: Rate or rhythm control for atrial fibrillation, cardioversion for unstable tachyarrhythmias. 1
• Hypertensive emergency: Aggressive blood pressure reduction with IV antihypertensives. 1

Additional Considerations

• Antibiotics if concomitant pneumonia or endocarditis is suspected. 1
• Anticoagulation for acute pulmonary embolism contributing to right heart failure. 1
• Inotropic support (dobutamine, milrinone) for forward failure with low cardiac output. 1
• Intra-aortic balloon pump for cardiogenic shock refractory to medical therapy. 1

Monitoring Response

• Serial BNP levels track treatment response. 1
• Repeat chest X-ray to document resolution of pulmonary edema. 1
• Echocardiography assesses improvement in cardiac function. 1
• In-hospital and one-year mortality for cardiac asthma (23% and 48%) are similar to CHF without wheeze, emphasizing the need for aggressive heart failure management. 3