Cardiac Asthma: A Comprehensive Review

Introduction

Cardiac asthma is a clinical condition characterised by wheezing, coughing, and shortness of breath resulting from heart failure rather than primary respiratory pathology. Despite sharing similar symptoms with bronchial asthma, cardiac asthma arises due to underlying cardiac dysfunction, most commonly left ventricular failure.

The epidemiology of cardiac asthma reflects the prevalence of heart failure, especially in populations with increasing age and incidence of hypertension, coronary artery disease, and valvular heart diseases. Understanding cardiac asthma is important because misdiagnosis can lead to inappropriate treatment, worsening of symptoms, and increased morbidity and mortality.

Definition and Overview

Cardiac asthma refers to a constellation of respiratory symptoms—most notably wheezing, dyspnoea, and cough—resulting from pulmonary congestion and oedema secondary to left-sided heart failure. Unlike bronchial asthma, which is caused by airway inflammation and hyperresponsiveness, cardiac asthma is due to increased pulmonary venous pressure, leading to fluid accumulation in the lungs. This results in airway narrowing and increased airway resistance, manifesting as asthmatic symptoms.

The term “cardiac asthma” was first introduced to distinguish these symptoms from those of true bronchial asthma, recognising their cardiac origin. Cardiac asthma is not a separate disease entity but rather a manifestation of acute or chronic left ventricular dysfunction, commonly seen in patients with congestive heart failure.

Pathophysiology

Mechanisms of Cardiac Asthma

The pathophysiology of cardiac asthma centres on the failure of the left ventricle to adequately pump blood, resulting in elevated left atrial and pulmonary venous pressures. This elevation leads to transudation of fluid into the pulmonary interstitial and alveolar spaces, causing pulmonary oedema. The accumulation of fluid in the lungs increases airway resistance and irritates airway receptors, resulting in bronchoconstriction and the classic symptoms of wheezing and dyspnoea.

Key mechanisms include:

• Increased Pulmonary Capillary Pressure: Left ventricular dysfunction causes blood to back up into the pulmonary circulation, raising capillary hydrostatic pressure and fluid leakage.
• Pulmonary Oedema: Fluid accumulates in the interstitial and alveolar spaces, impeding gas exchange and stimulating airway receptors.
• Reflex Bronchoconstriction: Stimulation of J-receptors and irritant receptors in the bronchial tree triggers reflex constriction, leading to wheezing.
• Airway Narrowing: Oedema and bronchoconstriction narrow airways, causing symptoms similar to bronchial asthma.

Underlying Heart Conditions and Triggers

Cardiac asthma most commonly occurs in the context of acute left ventricular failure, chronic congestive heart failure, or exacerbations of underlying cardiac conditions. Triggers include physical exertion, emotional stress, dietary indiscretion (e.g., excess salt intake), arrhythmias, and non-adherence to heart failure medications.

Etiology

Causes of Cardiac Asthma

The primary cause of cardiac asthma is left-sided heart failure, particularly when the left ventricle is unable to effectively pump blood forward, leading to pulmonary congestion. The following conditions commonly underlie cardiac asthma:

• Ischaemic Heart Disease: Myocardial infarction and chronic coronary artery disease can impair left ventricular function.
• Hypertensive Heart Disease: Chronic hypertension leads to left ventricular hypertrophy and eventual dysfunction.
• Valvular Heart Diseases: Mitral stenosis, mitral regurgitation, and aortic stenosis can result in increased left atrial pressure and pulmonary congestion.
• Cardiomyopathies: Dilated, restrictive, and hypertrophic cardiomyopathies may compromise cardiac output.
• Arrhythmias: Atrial fibrillation and other arrhythmias may precipitate heart failure and cardiac asthma.

Risk Factors

Several risk factors predispose individuals to cardiac asthma:

• Advanced age
• Hypertension
• Diabetes mellitus
• Coronary artery disease
• Valvular heart disease
• Previous myocardial infarction
• Obesity
• Chronic kidney disease
• Non-adherence to heart failure therapy

Associated Diseases

Cardiac asthma may be associated with other comorbidities, such as chronic obstructive pulmonary disease (COPD), bronchial asthma, renal failure, and anaemia, which can complicate diagnosis and management.

Clinical Presentation

Signs and Symptoms

Patients with cardiac asthma typically present with acute onset or worsening of respiratory symptoms, including:

• Dyspnoea: Shortness of breath, often worse at night (paroxysmal nocturnal dyspnoea) or when lying flat (orthopnoea).
• Wheezing: High-pitched whistling sounds heard during expiration, similar to bronchial asthma.
• Cough: Usually dry, but may become productive with pink, frothy sputum in severe pulmonary oedema.
• Tachypnoea: Rapid breathing rate.
• Chest Tightness: Sensation of constriction or discomfort.
• Fatigue: Generalised weakness due to poor cardiac output.

On physical examination, the following signs may be evident:

• Inspiratory crackles (crepitations) at lung bases
• Wheezing
• Elevated jugular venous pressure
• Peripheral oedema
• Gallop rhythm (S3 or S4 heart sounds)
• Cyanosis in severe cases

Patient History

A detailed history is essential for differentiating cardiac asthma from bronchial asthma. Key points include:

• History of heart disease, hypertension, or previous myocardial infarction
• Onset and progression of symptoms (sudden vs. gradual)
• Relationship of symptoms to physical activity or recumbency
• Associated symptoms such as chest pain, palpitations, or peripheral oedema
• Medication history and compliance

Diagnosis

Diagnostic Criteria

Diagnosis of cardiac asthma relies on clinical evaluation, supported by investigations that confirm underlying cardiac dysfunction and exclude primary respiratory disease. The following criteria are typically considered:

• Presence of characteristic respiratory symptoms (wheezing, dyspnoea, cough)
• Evidence of heart failure (clinical and investigative)
• Exclusion of bronchial asthma and other pulmonary conditions

Investigations

A variety of tests may be employed to confirm the diagnosis:

1. Chest X-ray: Shows cardiomegaly, pulmonary congestion, and oedema (Kerley B lines, perihilar haze).
2. Electrocardiogram (ECG): May reveal ischaemic changes, arrhythmias, or evidence of left ventricular hypertrophy.
3. Echocardiography: Assesses cardiac structure and function, identifies valvular disease, and quantifies ejection fraction.
4. B-type Natriuretic Peptide (BNP) or NT-proBNP: Elevated levels support the diagnosis of heart failure.
5. Blood Investigations: Assess renal function, electrolytes, and rule out infection or anaemia.
6. Pulmonary Function Tests: Help differentiate cardiac asthma from bronchial asthma or COPD.

Differential Diagnosis

It is crucial to distinguish cardiac asthma from other causes of wheezing and respiratory distress:

• Bronchial asthma
• Chronic obstructive pulmonary disease (COPD)
• Pulmonary embolism
• Pneumonia
• Anaphylaxis
• Acute respiratory distress syndrome (ARDS)

A detailed history, physical examination, and targeted investigations are necessary to confirm cardiac asthma and exclude these conditions.

Treatment and Management

Medical Management

The primary goal in treating cardiac asthma is to address the underlying heart failure, relieve symptoms, and prevent complications. Management strategies include:

1. Oxygen Therapy: Supplemental oxygen improves hypoxaemia and relieves dyspnoea.
2. Diuretics: Loop diuretics (e.g., furosemide) are administered to reduce pulmonary congestion by promoting fluid excretion.
3. Vasodilators: Agents such as nitrates and ACE inhibitors decrease preload and afterload, improving cardiac output.
4. Inotropes: Used in severe cases to support cardiac contractility (e.g., dobutamine).
5. Beta-blockers and ACE inhibitors: Long-term therapy to improve cardiac function and reduce morbidity.
6. Salt and Fluid Restriction: Dietary modifications to prevent fluid overload.
7. Treatment of Arrhythmias: Antiarrhythmic drugs or device therapy as indicated.
8. Management of Comorbidities: Addressing hypertension, diabetes, renal dysfunction, etc.

Emergency Care

Patients presenting with acute pulmonary oedema and severe respiratory distress require immediate stabilisation. Emergency measures include:

• High-flow oxygen via mask or nasal cannula
• Intravenous loop diuretics
• Intravenous vasodilators (nitroglycerin)
• Non-invasive ventilation (CPAP or BiPAP) if indicated
• Monitoring of vital signs and cardiac rhythm
• Treating underlying precipitating factors (e.g., myocardial infarction, arrhythmias)

Long-Term Strategies

Long-term management focuses on optimising heart failure therapy, preventing exacerbations, and improving quality of life:

• Regular follow-up and monitoring of cardiac function
• Adjustment of medications as per guidelines
• Patient education on symptom recognition and medication adherence
• Rehabilitation and lifestyle modifications
• Vaccination against influenza and pneumococcus to prevent infections

Prognosis and Complications

Outcomes

The prognosis of cardiac asthma largely depends on the underlying cardiac condition and the timeliness of intervention. Prompt recognition and appropriate management can lead to symptom resolution and improved survival. However, recurrent episodes are common in advanced heart failure, and the overall prognosis may be poor if underlying cardiac dysfunction is severe.

Complications

Potential complications include:

• Recurrent pulmonary oedema
• Respiratory failure
• Arrhythmias
• Renal dysfunction
• Multi-organ failure in severe cases
• Reduced quality of life due to frequent hospitalisations and persistent symptoms

Quality of Life

Patients with cardiac asthma often experience limitations in daily activities, increased dependence on healthcare services, and psychological distress. Comprehensive management, including medical, rehabilitative, and psychosocial support, is essential to enhance their quality of life.

Prevention and Patient Education

Preventive Measures

Preventing cardiac asthma involves controlling risk factors and optimising management of underlying heart disease:

• Strict control of hypertension, diabetes, and other comorbidities
• Early detection and treatment of heart disease
• Adherence to prescribed heart failure medications
• Regular follow-up with healthcare providers
• Dietary modifications: reduced salt intake, fluid restriction as advised
• Weight management and regular physical activity (as per tolerance)
• Avoidance of triggers such as excess salt, strenuous activity, and emotional stress

Patient Education

Patient education is vital for preventing exacerbations and improving outcomes. Healthcare professionals should educate patients on:

• Recognising early warning signs of heart failure and cardiac asthma
• Importance of medication adherence and regular check-ups
• Lifestyle modifications, including dietary changes and physical activity
• Management of comorbidities
• When to seek emergency care (e.g., sudden severe breathlessness, chest pain)
• Role of vaccinations in preventing respiratory infections

Nursing Care of Patients with Cardiac Asthma

Cardiac asthma is a medical emergency, and nurses play a pivotal role in the recognition, management, and ongoing care of patients with this condition. This document provides an in-depth exploration of nursing responsibilities, patient assessment, interventions, and education for those suffering from cardiac asthma.

Nursing Assessment

A thorough assessment is essential to distinguish cardiac asthma from other respiratory disorders and to guide effective interventions.

History Taking

• Gather information about any history of chronic heart disease, hypertension, myocardial infarction, or valvular disorders.
• Assess for previous episodes of similar symptoms and their triggers.
• Document medication history and compliance, especially with cardiac medications and diuretics.

Physical Examination

• Monitor respiratory rate, oxygen saturation, use of accessory muscles, and work of breathing.
• Auscultate for crackles (rales) and wheezing in the lungs.
• Check for signs of fluid overload: peripheral edema, elevated jugular venous pressure.
• Assess for cyanosis, pallor, and diaphoresis.
• Monitor vital signs frequently: temperature, pulse, blood pressure, and respiratory rate.

Diagnostic Support

• Assist in obtaining chest X-rays, ECGs, and echocardiograms as ordered.
• Monitor blood tests such as B-type natriuretic peptide (BNP), arterial blood gases (ABG), and serum electrolytes.

Nursing Diagnoses

Common nursing diagnoses in cardiac asthma include:

• Ineffective breathing pattern related to pulmonary congestion and airway narrowing
• Impaired gas exchange related to alveolar-capillary membrane changes
• Decreased cardiac output related to left ventricular dysfunction
• Fluid volume excess related to compromised cardiac function
• Anxiety related to breathlessness and fear of suffocation
• Knowledge deficit regarding condition and management

Nursing Interventions

Immediate Care

• Positioning: Place the patient in a semi-Fowler’s or high-Fowler’s position to enhance diaphragmatic movement and reduce pulmonary congestion.
• Oxygen Therapy: Administer supplemental oxygen as prescribed to maintain adequate oxygenation. Monitor for signs of hypoxia and oxygen toxicity.
• Vital Signs Monitoring: Monitor blood pressure, pulse, respiratory rate, and oxygen saturation frequently and report significant changes to the physician.
• Airway Management: Ensure airway patency. Be prepared for advanced airway interventions if respiratory distress worsens.
• Medication Administration: Administer prescribed medications, including diuretics (e.g., furosemide), vasodilators, and inotropic agents to reduce cardiac preload and afterload.
• Monitor Intake and Output: Accurately measure fluid intake and urinary output to assess the effectiveness of diuretics and detect fluid overload.
• Reassurance: Provide emotional support and reassurance to reduce anxiety, which can exacerbate dyspnea.

Ongoing and Supportive Care

• Monitor Response to Therapy: Observe for improvement in breathlessness, reduction in crackles, and increased urine output after diuretic therapy.
• Skin Care: Prevent pressure ulcers by regular repositioning, especially in patients requiring prolonged bed rest.
• Prevent Complications: Be vigilant for complications such as arrhythmias, worsening heart failure, or infections such as pneumonia.
• Fluid Restriction: If prescribed, ensure adherence to fluid restriction to prevent further pulmonary congestion.
• Nutritional Support: Encourage small, frequent meals and assist with feeding if required to avoid fatigue from eating.
• Patient and Family Education: Teach the importance of medication compliance, daily weight monitoring, dietary sodium restriction, and recognizing early signs of fluid retention.
• Discharge Planning: Facilitate a multidisciplinary approach for discharge planning, involving dietitians, physiotherapists, and social workers as needed.

Patient and Family Education

Education is a cornerstone of effective long-term management and relapse prevention.

• Explain the difference between cardiac asthma and bronchial asthma to avoid confusion and inappropriate self-medication (e.g., use of bronchodilators without indication).
• Guide on dietary modifications: low-sodium diet, fluid restriction, and avoidance of alcohol or substances that exacerbate heart failure.
• Stress the importance of adhering to prescribed cardiac medications such as ACE inhibitors, beta-blockers, and diuretics.
• Teach how to monitor daily weight, recognize symptoms of fluid retention, and seek early medical attention if they occur.
• Discuss lifestyle modifications: quit smoking, engage in tailored physical activity, manage comorbidities such as hypertension or diabetes, and attend regular medical follow-ups.
• Provide information about community resources and support groups for patients with chronic heart failure.

Psychosocial Support

• Recognize the psychological impact of cardiac asthma, including anxiety and depression.
• Offer counseling or referrals to mental health professionals as indicated.
• Encourage participation in cardiac rehabilitation programs if available.

Coordination with the Healthcare Team

The nurse serves as a vital link between the patient, family, and broader healthcare team.

• Communicate patient status changes, response to treatment, and concerns promptly to physicians and allied health professionals.
• Collaborate with pharmacists regarding medication adjustments and potential drug interactions.
• Engage physiotherapists to assist with breathing exercises, mobility, and rehabilitation.
• Coordinate with dietitians to develop tailored meal plans that support cardiac health.

Prevention and Health Promotion

• Encourage regular health check-ups for early detection of left ventricular dysfunction and heart failure risk factors.
• Promote blood pressure and blood sugar control in patients with hypertension or diabetes.
• Educate the public about heart-healthy lifestyles, including proper nutrition, exercise, and smoking cessation.
• Facilitate vaccination against influenza and pneumococcal infections to reduce respiratory complications.

Special Considerations

Care in Older Adults

Elderly patients may present with atypical symptoms and have multiple comorbidities. Adjust care to accommodate frailty, cognitive impairment, and polypharmacy.

Ethical and Cultural Sensitivity

Respect the patient’s beliefs and preferences in care decisions. Address language barriers and engage interpreters as needed.

REFERENCES

1. Buckner K. Cardiac asthma. https://pubmed.ncbi.nlm.nih.gov/23337063/. Immunol Allergy Clin North Am. 2013 Feb;33(1):35-44.
2. MedlinePlus. Asthma. https://medlineplus.gov/asthma.html.
3. Inamdar AA, Inamdar AC. Heart failure: Diagnosis, management and utilization. J Clin Med. 2016;5(7):62. doi:10.3390/jcm5070062
4. National Heart, Lung, and Blood Institute. Heart Failure. https://www.nhlbi.nih.gov/health-topics/heart-failure.
5. Aaron SD, Vandemheen KL, Fitzgerald JM, et al. Reevaluation of diagnosis in adults with physician-diagnosed asthma. JAMA. 2017;317(3):269-79. doi:10.1001/jama.2016.19627
6. Tanabe T, Rozycki HJ, Kanoh S, Rubin BK. Cardiac asthma: new insights into an old disease. Expert Rev Respir Med. 2012 Dec;6(6):705-14. doi: 10.1586/ers.12.67. PMID: 23234454.

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