What is congestive heart failure?

What is Congestive Heart Failure?

Congestive heart failure is a clinical syndrome in which the heart cannot pump enough blood to meet the body's metabolic needs, characterized by symptoms of breathlessness and fatigue, signs of fluid retention (pulmonary congestion and peripheral edema), and objective evidence of cardiac structural or functional abnormality at rest. 1, 2

Core Definition and Diagnostic Criteria

Heart failure requires three essential components for diagnosis: 1, 2

• Symptoms of heart failure (at rest or during exercise): typically breathlessness, fatigue, or ankle swelling 1
• Objective evidence of cardiac dysfunction (preferably by echocardiography): structural and/or functional abnormality of the heart at rest 1, 2
• Response to treatment directed at heart failure (when diagnosis is in doubt): improvement with diuretics or vasodilators, though this alone is insufficient for diagnosis 1

The term "heart failure" is now preferred over "congestive heart failure" because not all patients have volume overload at initial or subsequent evaluation—some present with exercise intolerance but minimal fluid retention, while others have predominantly edema with few respiratory symptoms. 1, 2

Pathophysiological Basis

Heart failure results from any structural or functional cardiac disorder that impairs the ventricle's ability to fill with or eject blood, leading to reduced cardiac output and/or elevated intracardiac pressures. 1, 2

The syndrome can arise from disorders of: 2

• Myocardium (most common): ischemic heart disease, hypertension, dilated cardiomyopathy
• Valves: valvular heart disease
• Pericardium, endocardium, or great vessels
• Cardiac rhythm and conduction abnormalities

Coronary artery disease causes approximately two-thirds of cases in developed countries, making it the predominant etiology, with the remaining one-third from nonischemic causes including hypertension, valvular disease, myocardial toxins, myocarditis, or idiopathic dilated cardiomyopathy. 1, 3

Classification by Ejection Fraction

Heart failure is classified into three categories based on left ventricular ejection fraction (LVEF): 2

• Heart Failure with Reduced Ejection Fraction (HFrEF): LVEF <40%
• Heart Failure with Mid-range Ejection Fraction (HFmrEF): LVEF 40-49%
• Heart Failure with Preserved Ejection Fraction (HFpEF): LVEF ≥50%

Both systolic and diastolic dysfunction typically coexist regardless of ejection fraction, though most cases show evidence of left ventricular systolic dysfunction. 1 Diastolic heart failure is more common in elderly patients and women, frequently associated with systolic hypertension and myocardial hypertrophy with fibrosis. 1, 2

Cardinal Clinical Manifestations

The hallmark symptoms are dyspnea and fatigue (which limit exercise tolerance), and fluid retention (which causes pulmonary congestion and peripheral edema). 1, 2

Common Symptoms: 1, 2

• Breathlessness (at rest or with exertion)
• Fatigue and exercise intolerance
• Ankle swelling
• Orthopnea (difficulty breathing when lying flat)
• Paroxysmal nocturnal dyspnea (sudden nighttime breathlessness)

Common Physical Signs: 2, 4

• Elevated jugular venous pressure
• Pulmonary rales (crackles): the hallmark lung finding indicating pulmonary congestion
• Peripheral edema
• S3 gallop rhythm
• Hepatomegaly and hepatojugular reflux

A critical caveat: symptoms like breathlessness, ankle swelling, and fatigue may be difficult to interpret, particularly in elderly patients, obese individuals, and women, requiring careful assessment of different modes (effort-related versus nocturnal). 1

Important Clinical Distinctions

Heart failure should never be the only diagnosis—the underlying cardiac cause must always be identified, as the precise pathology determines specific treatment approaches. 1, 2

Heart failure is not equivalent to cardiomyopathy or left ventricular dysfunction; these terms describe possible structural or functional reasons for developing heart failure, whereas heart failure itself is a clinical syndrome diagnosed primarily through careful history and physical examination. 1

Acute versus Chronic Heart Failure: 2

• Acute heart failure: rapid onset or worsening of symptoms requiring urgent treatment
• Chronic heart failure: persistent state, often punctuated by acute exacerbations

Right versus Left Heart Failure: 1

• These terms refer to syndromes presenting predominantly with congestion of systemic or pulmonary veins, respectively
• They do not necessarily indicate which ventricle is most severely damaged

The Progressive Nature of Disease

Heart failure is a progressive disease with established risk factors, asymptomatic phases, and symptomatic phases—analogous to cancer staging. 3 Ventricular remodeling (the principal manifestation of disease progression) represents homeostatic attempts to decrease wall stress through increases in wall thickness, resulting in geometric changes where the left ventricle dilates, hypertrophies, and becomes more spherical. 3

A poorly understood discordance exists between ejection fraction severity and functional impairment—patients with very low ejection fractions may be asymptomatic while those with preserved systolic function may have severe disability. 3

Epidemiology and Impact

Approximately 5.8 million people in the United States have heart failure, making it one of the most common reasons those aged 65 and over are hospitalized. 5 Despite significant understanding of underlying pathophysiological mechanisms, this disease causes substantial morbidity and carries a 50% 5-year mortality. 6