What is heart failure, including its pathophysiology, investigation, treatment, and follow-up?

Heart Failure: Pathophysiology, Investigation, and Management

Heart failure is a clinical syndrome characterized by typical symptoms such as breathlessness, fatigue, and ankle swelling, caused by a structural and/or functional cardiac abnormality resulting in reduced cardiac output and/or elevated intracardiac pressures at rest or during stress. 1

Definition and Classification

• Heart failure is defined by the presence of symptoms (typically breathlessness, fatigue, or ankle swelling) AND objective evidence of cardiac dysfunction at rest 1
• Heart failure is classified based on left ventricular ejection fraction (LVEF) into:
  • Heart failure with reduced ejection fraction (HFrEF): LVEF ≤40% 1, 2
  • Heart failure with mid-range ejection fraction (HFmrEF): LVEF 40-49% 1
  • Heart failure with preserved ejection fraction (HFpEF): LVEF ≥50% 1, 2
• Severity is commonly assessed using the New York Heart Association (NYHA) functional classification, ranging from class I (no limitation of physical activity) to class IV (symptoms at rest) 1, 2

Pathophysiology

• Heart failure results from injury to the myocardium from various causes including ischemic heart disease, hypertension, and diabetes 3
• Following cardiac injury, several compensatory mechanisms occur: 4, 3
  • Frank-Starling mechanism (increased preload to maintain cardiac output)
  • Ventricular remodeling (increased ventricular volume and wall thickness)
  • Neurohormonal activation (sympathetic nervous system and renin-angiotensin-aldosterone system)
• These initially beneficial compensatory mechanisms eventually lead to a vicious cycle of worsening heart failure 3
• Symptoms arise from:
  • Increased pulmonary capillary pressure causing pulmonary edema and breathlessness 1
  • Low cardiac output leading to fatigue and peripheral hypoperfusion 1
  • Fluid retention causing peripheral edema and hepatomegaly 1

Clinical Presentation

• Characteristic symptoms include: 1
  • Breathlessness (at rest or during exertion)
  • Fatigue
  • Ankle swelling
• Common signs include: 1
  • Elevated jugular venous pressure
  • Pulmonary crackles
  • Peripheral edema
  • Third heart sound (S3 gallop)
  • Displaced cardiac apex
• The relationship between symptoms and severity of cardiac dysfunction is often poor 1

Investigation

• Initial evaluation should include: 5
  • History and physical examination
  • Chest radiography (to identify venous congestion or interstitial edema)
  • Electrocardiography
  • Laboratory assessment (including renal function, electrolytes)
• Echocardiography is the diagnostic standard to confirm heart failure through assessment of left ventricular ejection fraction 5
• B-type natriuretic peptide (BNP) or NT-proBNP measurement is valuable for diagnosis, with normal levels making systolic heart failure unlikely 4, 5
• Additional investigations may include: 1, 6
  • Evaluation for ischemic heart disease (especially if angina is present)
  • Cardiac MRI for specific etiologies
  • Pulmonary function tests to exclude respiratory causes

Treatment

Pharmacological Management

• Core pharmacological therapy for HFrEF includes: 6
  • ACE inhibitors/ARBs/ARNIs (first-line therapy for mortality reduction)
  • Beta-blockers (essential for reducing mortality and hospitalizations)
  • Mineralocorticoid receptor antagonists (MRAs)
  • SGLT2 inhibitors (newer addition with proven mortality benefit)
• Diuretics are essential for symptomatic treatment of fluid overload 7, 2, 6
• Additional therapies for selected patients may include: 6
  • Hydralazine and isosorbide dinitrate (particularly beneficial in African American patients)
  • Digoxin (to reduce symptoms and enhance exercise tolerance)

Management of Acute Decompensation

• For acute heart failure: 7, 6
  • Monitor heart rate, rhythm, blood pressure, and oxygen saturation continuously
  • Maintain oxygen saturation above 90%
  • Promptly administer diuretics to relieve congestion
  • Consider inotropic support (dobutamine, milrinone) for patients with low cardiac output

Non-Pharmacological Management

• Patient education about heart failure, symptom recognition, and self-monitoring 2
• Daily weight monitoring with reporting of weight gains >2 kg in 3 days 2
• Moderate sodium restriction and regular physical activity 2
• Exercise training to improve clinical status in ambulatory patients 6

Advanced Heart Failure Management

• For refractory heart failure (Stage D), consider: 6
  • Mechanical circulatory support
  • Heart transplantation
  • Palliative care for improving quality of life

Follow-up

• Schedule early follow-up within 7-14 days after hospital discharge 2, 6
• Implement multidisciplinary heart failure disease-management programs 2, 6
• Monitor renal function and electrolytes regularly, especially after medication dose changes 6
• Before discharge, ensure: 7
  • The acute episode has resolved
  • Congestion is absent
  • A stable oral diuretic regimen has been established for at least 48 hours

Common Pitfalls to Avoid

• Inadequate diuresis in volume-overloaded patients 2
• Failure to uptitrate medications to target doses 2
• Neglecting patient education and self-care strategies 2
• Inadequate transitional care planning leading to early readmissions 2
• Excessive fluid administration in patients with right ventricular dilation 7