Acute Heart Failure

Acute heart failure (AHF) represents a critical and rapidly evolving medical condition that requires urgent diagnosis and intervention. Unlike chronic heart failure, which develops gradually over time, acute heart failure is characterized by the sudden onset or rapid worsening of the symptoms and signs associated with heart failure. This comprehensive guide explores the pathophysiology, causes, clinical features, diagnosis, and management strategies associated with acute heart failure.

What Is Acute Heart Failure?

Acute heart failure occurs when the heart is unable to pump blood efficiently enough to meet the body’s metabolic demands, either because of a sudden insult or an acute decompensation of chronic heart failure. The resultant decrease in cardiac output leads to a cascade of neurohormonal responses, fluid overload, and congestion of vital organs. The rapid progression distinguishes AHF from chronic forms, making immediate attention essential.

Causes and Risk Factors

Primary Causes

• Acute Myocardial Infarction (AMI): A heart attack can severely impair heart muscle function, leading to acute pump failure.
• Arrhythmias: Rapid or irregular heart rhythms (such as atrial fibrillation or ventricular tachycardia) compromise effective cardiac output.
• Acute Valve Dysfunction: Sudden failure of heart valves, especially mitral or aortic, can drastically alter hemodynamics.
• Hypertensive Crisis: Severe, uncontrolled hypertension increases afterload, overwhelming the heart’s ability to pump.
• Pulmonary Embolism: A large clot in the lungs can suddenly increase right heart strain, resulting in failure.
• Cardiac Tamponade: Fluid accumulation in the pericardial sac exerts pressure on the heart, hampering its function.
• Acute Myocarditis: Inflammation of the heart muscle from infections or toxins may trigger AHF.

Decompensation of Chronic Heart Failure

Many patients with pre-existing chronic heart failure experience acute decompensation due to:

• Dietary indiscretions (excess salt or fluid intake)
• Nonadherence to medications
• Infections (respiratory or systemic)
• Renal dysfunction
• Drug toxicity (such as NSAIDs, some chemotherapy drugs)

Risk Factors

• Age above 65 years
• Coronary artery disease
• Diabetes mellitus
• Chronic kidney disease
• Hypertension
• Obesity
• Prior history of myocardial infarction
• Valvular heart disease

Pathophysiology

Acute heart failure can manifest in two broad scenarios:

• Acute Decompensation of Chronic Heart Failure: The most common scenario, where a patient with stable chronic heart failure experiences a rapid deterioration. Fluid overload and neurohormonal activation predominate.
• De novo Acute Heart Failure: Sudden onset of heart failure in an individual with previously normal cardiac function, often due to a catastrophic event such as acute myocardial infarction.

The fundamental problem is either inadequate forward flow (low cardiac output) or congestion (fluid overload) or both. This leads to:

• Activation of the sympathetic nervous system
• Stimulation of the renin-angiotensin-aldosterone system (RAAS)
• Fluid retention and worsening pulmonary and systemic congestion
• Organ hypoperfusion, further worsening the patient’s status

Clinical Features

The presentation of acute heart failure can be dramatic or subtle, and varies based on the underlying cause and the rapidity of onset.

Common Signs and Symptoms

• Sudden onset of breathlessness (dyspnea), especially on exertion or while lying flat (orthopnea)
• Paroxysmal nocturnal dyspnea (waking at night breathless)
• Rapid weight gain from fluid retention
• Cough, often with frothy sputum (sometimes pink-tinged)
• Fatigue and weakness
• Swelling in the legs, ankles, or abdomen (peripheral edema, ascites)
• Distended neck veins (jugular venous distension)
• Rapid or irregular heartbeat (palpitations)
• Low blood pressure (in severe cases)

Physical Examination Findings

• Tachycardia (rapid heart rate)
• Tachypnea (rapid breathing)
• Basal lung crackles (rales) on auscultation
• Third heart sound (S3 gallop)
• Cool clammy skin (in severe cases with low output)
• Hepatomegaly (enlarged liver)

Diagnosis

Prompt and accurate diagnosis is crucial for initiating appropriate therapy and improving outcomes.

Initial Assessment

• Detailed history and physical examination
• Assessment of vital signs (blood pressure, heart rate, oxygen saturation)

Laboratory and Imaging Investigations

• Electrocardiogram (ECG): To detect arrhythmias, ischemia, or infarction.
• Chest X-ray: To assess pulmonary congestion, cardiomegaly, or pleural effusions.
• Blood tests: Including complete blood count, renal and liver function, electrolytes, and biomarkers such as B-type natriuretic peptide (BNP) or N-terminal proBNP (NT-proBNP).
• Echocardiography: Key tool for assessing heart structure and function, identifying valvular disease, pericardial effusion, and ejection fraction.
• Additional tests: Cardiac troponins (to rule out myocardial injury), arterial blood gases (for hypoxia or acidosis).

Management of Acute Heart Failure

The management of AHF hinges on rapid stabilization, identification and reversal of precipitating causes, and supportive care. The overall goals are to relieve symptoms, improve organ perfusion, prevent further cardiac damage, and reduce the risk of mortality.

Initial Stabilization

• Ensuring airway patency and adequate oxygenation—supplemental oxygen, and in severe cases, non-invasive or invasive ventilation.
• Monitoring vital signs and cardiac rhythm continuously.
• Establishing intravenous access for medications and fluids.

Pharmacologic Therapies

• Diuretics: Loop diuretics (such as furosemide) are first-line to relieve symptoms of congestion and fluid overload.
• Vasodilators: Agents such as nitroglycerin or nitroprusside may be used to decrease preload and afterload, easing the heart’s workload.
• Inotropes: Medications like dobutamine or milrinone may be used in cases of low cardiac output with hypotension, to temporarily boost heart contractility.
• Vasopressors: Used in cases of shock to maintain blood pressure and organ perfusion.
• Other agents: Depending on specific triggers (for example, beta-blockers in certain arrhythmias once stabilized).

Treatment of Precipitating and Underlying Causes

• Rapid revascularization in acute myocardial infarction (angioplasty, thrombolysis)
• Correction of arrhythmias (electrical or pharmacological cardioversion)
• Repair or replacement of acutely failing heart valves
• Treatment of infections (antibiotics for pneumonia or sepsis)
• Withdrawal of offending medications or toxins
• Management of hypertensive emergencies

Non-Pharmacologic Interventions

• Fluid and salt restriction
• Daily monitoring of body weight and urine output
• Mechanical circulatory support in refractory cases (intra-aortic balloon pump, ventricular assist devices, extracorporeal membrane oxygenation, or ECMO)

Prognosis and Outcomes

Acute heart failure carries a significant risk of morbidity and mortality, especially in the elderly and those with multiple comorbidities. The in-hospital mortality rate can range between 4-12%, and the risk of rehospitalization or death within months of discharge remains high.

The prognosis depends on:

• Underlying etiology (e.g., acute myocardial infarction vs. decompensated chronic heart failure)
• Severity of symptoms and degree of organ dysfunction at presentation
• Speed and effectiveness of treatment
• Presence of comorbid conditions

Early recognition and aggressive management can improve survival and quality of life for patients.

Prevention

While not all episodes of acute heart failure are preventable, several strategies can reduce the likelihood of decompensation:

• Strict adherence to chronic heart failure therapy and follow-up
• Regular monitoring for early signs of fluid overload (weight gain, swelling)
• Restriction of dietary salt and fluid intake as recommended
• Control of blood pressure and diabetes
• Vaccination against respiratory infections (influenza, pneumococcus)
• Education regarding medication compliance and self-care

Nursing Care of Patients with Acute Heart Failure

Oxygenation and Respiratory Support

• Administer supplemental oxygen as prescribed to maintain SpO2 above 94%.
• Position patient in semi-Fowler’s or upright position to improve lung expansion and reduce dyspnoea.
• Monitor for signs of hypoxia and respiratory distress; initiate advanced airway support if needed.

Medication Administration and Management

• Administer prescribed diuretics, vasodilators, inotropes, and other medications as per protocol.
• Monitor for adverse effects such as electrolyte imbalances (especially potassium), hypotension, and renal dysfunction.
• Educate patient and family about the purpose and possible side effects of medications.

Management of Fluid Overload

• Implement fluid restriction as advised by the physician.
• Monitor for signs of worsening fluid retention, such as increasing weight, swelling, or crackles on lung auscultation.
• Encourage patient to report new or worsening symptoms promptly.

Nutritional Support

• Encourage a low-sodium diet to help control fluid retention.
• Monitor nutritional intake and consult a dietician if needed for individualised dietary planning.
• Assess for signs of malnutrition, especially in elderly or chronically ill patients.

Prevention of Complications

• Reposition patient regularly to prevent pressure ulcers and promote circulation.
• Encourage early mobilisation as tolerated to prevent deep vein thrombosis (DVT).
• Monitor for arrhythmias and worsening cardiac function.
• Maintain strict infection control practices to reduce risk of hospital-acquired infections.

Patient and Family Education

• Provide information about heart failure, its management, and warning signs of deterioration.
• Educate on lifestyle modifications such as dietary changes, exercise, medication adherence, and smoking cessation.
• Offer psychological support and address concerns regarding prognosis and quality of life.

Discharge Planning and Follow-Up

• Coordinate with multidisciplinary team for comprehensive discharge planning.
• Ensure patient and family understand medication regimen, follow-up appointments, and when to seek immediate medical attention.
• Facilitate referrals to cardiac rehabilitation or home care services as necessary.

REFERENCES

1. Arrigo M, Jessup M, Mullens W, et al. Acute heart failure. https://pubmed.ncbi.nlm.nih.gov/32139695/. Nat Rev Dis Primers. 2020 Mar 5;6(1):16.
2. Čerlinskaitė K, Javanainen T, Cinotti R, Mebazaa A; Global Research on Acute Conditions Team (GREAT) Network. Acute Heart Failure Management. https://pubmed.ncbi.nlm.nih.gov/29856141/. Korean Circ J. 2018 Jun;48(6):463-480.
3. Collins S, Storrow AB, Albert NM, et al. Early management of patients with acute heart failure: state of the art and future directions. https://pubmed.ncbi.nlm.nih.gov/25042620/. J Card Fail. 2015 Jan;21(1):27-43.
4. Kuo DC, Peacock WF. Diagnosing and managing acute heart failure in the emergency department. https://pubmed.ncbi.nlm.nih.gov/27752588/. Clin Exp Emerg Med. 2015 Sep 30;2(3):141-149.
5. Kurmani S, Squire I. Acute Heart Failure: Definition, Classification and Epidemiology. https://pubmed.ncbi.nlm.nih.gov/28785969/. Curr Heart Fail Rep. 2017 Oct;14(5):385-392.
6. Lala A, Mahmood K, Velazquez EJ. Evaluation and Management of Acute Heart Failure – Updated 8/2022. In: Fuster V, Narula J, Vaishnava P, Leon MB, et al., eds. Fuster and Hurst’s The Heart. 15th ed. McGraw-Hill Education; 2022.

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