What is the anatomy and physiology, definition, risk factors, causes, signs and symptoms, priority assessments, diagnostic testing, treatment, and nursing considerations for Congestive Heart Failure (CHF)?

Congestive Heart Failure (CHF): Comprehensive Clinical Overview

Anatomy and Physiology

Heart failure is a clinical syndrome resulting from any structural or functional cardiac disorder that impairs the ventricle's ability to fill with or eject blood. 1

• The left ventricle is most commonly affected, though disorders of the pericardium, myocardium, endocardium, valves, or great vessels can all lead to heart failure 2, 1
• The syndrome involves progressive cardiac remodeling where the left ventricular chamber dilates and/or hypertrophies, becoming more spherical, which increases hemodynamic stress on the ventricular walls and depresses mechanical performance 2
• This remodeling process may increase regurgitant flow through the mitral valve and continues even without new identifiable cardiac insults 2
• Both systolic and diastolic dysfunction typically coexist regardless of ejection fraction, though patients may present along a spectrum from normal left ventricular size with preserved ejection fraction to severe dilatation with markedly reduced ejection fraction 2

Definition

Heart failure is defined as a clinical syndrome characterized by specific symptoms (dyspnea and fatigue) in the medical history and signs (edema, rales) on physical examination, combined with objective evidence of cardiac dysfunction at rest. 2

• Heart failure is not equivalent to cardiomyopathy or left ventricular dysfunction—these terms describe possible structural or functional reasons for developing heart failure, but heart failure itself is a clinical diagnosis 2
• The term "heart failure" is preferred over "congestive heart failure" because not all patients have volume overload at initial or subsequent evaluations 2, 1
• Some patients have exercise intolerance with little fluid retention, while others complain primarily of edema with few symptoms of dyspnea or fatigue 2
• There is no single diagnostic test for heart failure; diagnosis is largely clinical based on careful history and physical examination 2

Risk Factors and Causes

Primary Causes

Coronary artery disease, hypertension, and dilated cardiomyopathy are the three dominant causes of heart failure in Western populations, with ischemic heart disease alone accounting for approximately 40% of all cases. 3

• Ischemic heart disease represents the single most common etiology globally, responsible for roughly 40% of heart failure cases, with highest rates in Eastern Europe and the Middle East 3
• Hypertension underlies 17-31% of heart failure cases and shows higher prevalence in heart failure with preserved ejection fraction (HFpEF) phenotypes 3
• Idiopathic dilated cardiomyopathy accounts for approximately 30% of cases in European registries, with up to 30% having an identifiable genetic cause 3
• Valvular heart disease remains a common cause, though less prevalent than the three primary etiologies 3

Secondary and Contributing Causes

• Diabetes mellitus directly damages myocardium and accelerates progression of existing heart failure 3
• Arrhythmias, particularly atrial fibrillation, can precipitate or worsen heart failure 3
• Cardiotoxic chemotherapy and mediastinal irradiation cause direct myocardial injury 3
• Illicit drug use (particularly cocaine and amphetamines) damages cardiac tissue 3
• Alcohol abuse leads to toxic cardiomyopathy 3
• Obesity increases hemodynamic burden and metabolic stress 3
• Thyroid dysfunction (both hyperthyroidism and hypothyroidism) alters cardiac performance 3
• Obstructive sleep apnea causes chronic hypoxemia and increased afterload 3
• Chronic kidney disease creates volume overload and neurohormonal activation 3

Special Populations

• Peripartum cardiomyopathy occurs during pregnancy or the postpartum period 3
• Adults with congenital heart disease have specific substrates including severe aortic stenosis/regurgitation from bicuspid aortic valve, unoperated atrial septal defects, Tetralogy of Fallot with surgical sequelae, and single-ventricle physiology with Fontan circulation 3

Signs and Symptoms

Cardinal Symptoms

The primary symptoms are dyspnea (breathlessness) and fatigue, either at rest or during exertion, along with ankle swelling. 2

• Symptoms are quantified using the New York Heart Association (NYHA) functional classification system 2:
  • Class I: Symptoms only at levels of exertion that would limit normal individuals 2
  • Class II: Symptoms on ordinary exertion 2
  • Class III: Symptoms on less-than-ordinary exertion 2
  • Class IV: Symptoms at rest 2

Physical Examination Findings

• Pulmonary rales indicating pulmonary congestion 2
• Peripheral edema (ankle swelling) 2
• Elevated jugular venous pressure 2
• Third heart sound (S3 gallop) 2
• Displaced apical impulse suggesting cardiomegaly 2

Important Clinical Considerations

There is a poor relation between measures of cardiac performance and symptoms produced by the disease—patients with very low ejection fraction may be asymptomatic, whereas patients with preserved left ventricular ejection fraction may have severe disability. 2

• This discordance may be explained by alterations in ventricular distensibility, valvular regurgitation, pericardial restraint, cardiac rhythm, conduction abnormalities, and right ventricular function 2
• Noncardiac factors contributing to exercise intolerance include changes in peripheral vascular function, skeletal muscle physiology, pulmonary dynamics, neurohormonal and reflex autonomic activity, and renal sodium handling 2
• Symptom severity characteristically fluctuates even without changes in medications, and changes in medications and diet can have favorable or adverse effects on functional capacity without measurable changes in ventricular function 2

Priority Assessments and Critical Red Flags

Initial Assessment

A thorough history and physical examination should be obtained in patients presenting with heart failure to identify cardiac and noncardiac disorders that might cause or accelerate the development or progression of heart failure. 2

Critical Red Flags Requiring Immediate Attention

• Cardiogenic shock: Hypotension (systolic blood pressure <90 mmHg) with evidence of peripheral vasoconstriction such as oliguria, cyanosis, and sweating 2
• Frank pulmonary edema: Rales throughout the lung fields indicating severe heart failure 2
• Acute decompensation: New or worsening dyspnea at rest, particularly with orthopnea or paroxysmal nocturnal dyspnea 2
• Signs of poor perfusion: Cool extremities, altered mental status, decreased urine output 2
• Hemodynamic instability: Persistent hypotension, tachycardia, or bradycardia 4

Continuous Monitoring Requirements

• Monitor heart rate, rhythm, blood pressure, and oxygen saturation continuously for at least the first 24 hours in acute presentations 4
• Maintain oxygen saturation above 90% at all times 4
• Consider pulmonary artery catheterization in patients who are refractory to pharmacological treatment, persistently hypotensive, or have uncertain left ventricular filling pressure 4

Diagnostic Testing and Labs

Essential Initial Tests

An electrocardiogram should be performed in every patient with suspected heart failure—if the ECG is completely normal, heart failure, especially with systolic dysfunction, is unlikely (<10%). 2

• Chest X-ray (in two planes) is essential to assess pulmonary congestion, cardiomegaly, pleural fluid accumulation, and to detect pulmonary disease or infection causing or contributing to dyspnea 2
• Echocardiography is the most useful method for evaluating systolic and diastolic dysfunction and should be performed to confirm diagnosis and assess cardiac structure and function 2

Natriuretic Peptides

Plasma concentrations of natriuretic peptides are useful biomarkers in diagnosis: 2

• BNP <100 pg/mL or NT-proBNP <400 pg/mL: Chronic heart failure unlikely 2
• BNP 100-400 pg/mL or NT-proBNP 400-2000 pg/mL: Uncertain diagnosis 2
• BNP >400 pg/mL or NT-proBNP >2000 pg/mL: Chronic heart failure likely 2

Routine Laboratory Tests

A routine diagnostic evaluation includes: 2

• Complete blood count (hemoglobin, leukocytes, platelets) 2
• Serum electrolytes (sodium, potassium) 2
• Serum creatinine and estimated glomerular filtration rate (GFR) 2
• Glucose 2
• Liver function tests 2
• Urinalysis 2

Additional Diagnostic Considerations

• Marked hematological or electrolyte abnormalities are uncommon in untreated mild to moderate heart failure, though mild anemia, hyponatremia, hyperkalaemia, and reduced renal function are common, especially in patients treated with diuretics and ACE inhibitors/ARBs/aldosterone antagonists 2
• Echocardiography should be performed in patients with COPD who have signs of congestive heart failure or concerning symptoms to differentiate between left heart failure and cor pulmonale 1

Relevant Labs and Vital Targets

Monitoring Parameters

Appropriate laboratory monitoring is essential during initiation, titration, and follow-up phases in patients receiving drug therapy for heart failure. 2

• Monitor renal function, electrolytes, potassium, and sodium daily during IV therapy and when adjusting renin-angiotensin-aldosterone system antagonists 4
• Oxygen saturation target: >90% at all times 4
• Blood pressure: Avoid hypotension, particularly systolic blood pressure <90 mmHg which indicates cardiogenic shock 2

Key Laboratory Targets

• Serum potassium: Monitor closely with ACE inhibitors, ARBs, and aldosterone antagonists to avoid hyperkalemia 2
• Serum sodium: Monitor for hyponatremia, particularly with diuretic therapy 2
• Renal function: Monitor creatinine and estimated GFR regularly, as chronic kidney disease complicates heart failure management 3

Treatment and Procedures

Pharmacological Management - Disease-Modifying Therapy

ACE inhibitors are recommended as first-line therapy in patients with reduced left ventricular systolic function, as they improve left ventricular function and survival. 4

• Start with a low dose and build up to recommended maintenance dosages shown to be effective in large trials 4
• For patients who cannot take an ACE inhibitor, the combination of hydralazine and nitrates may offer some prognostic benefit 5
• Unless contraindicated, patients with left ventricular systolic dysfunction should receive high-dose ACE inhibitor with diuretic if there is peripheral edema 5

Symptomatic Management

Loop diuretics (e.g., furosemide) are essential for symptomatic treatment when fluid overload is present with pulmonary congestion or peripheral edema. 4

• Diuretics remain an important component of symptomatic management but must be used cautiously in isolated right ventricular failure to avoid compromising right ventricular filling pressure 4
• Severely symptomatic patients may require additional agents beyond diuretics 5
• One option for patients exhibiting resistance to loop diuretics is infusion of low-dose dopamine 5
• Combination diuretics may effectively increase urine output with the addition of thiazide or spironolactone 5

Digoxin

• Digoxin remains in standards of therapy for heart failure 5
• It has been the traditional first drug of choice for heart failure, though with protracted controversy about its efficacy and safety 5

Inotropic Support (Acute Settings)

• Dobutamine at 2.5-5.0 μg/kg/min can improve right ventricular output 4
• Consider milrinone (0.25-0.75 μg/kg/min) as an alternative inotrope, particularly for its additional pulmonary vasodilatory effects, but monitor for hypotension 4

Cause-Specific Management

For right ventricular infarction, perform urgent coronary angiography and revascularization immediately for acute coronary syndrome with right ventricular involvement. 4

• For right ventricular infarction, administer volume loading with normal saline (500-ml bolus, followed by 500 ml/h) unless there are signs of left heart volume overload 4
• For pulmonary hypertension-related right heart failure, pulmonary vasodilators are the cornerstone of treatment including type V phosphodiesterase inhibitors, endothelin antagonists, and prostacyclin analogues 4
• For valvular disease, perform transesophageal echocardiography to rule out structural defects and obtain surgical consultation early, particularly for severe acute aortic or mitral regurgitation 4

Mechanical Circulatory Support

• Consider intra-aortic balloon pump or other mechanical circulatory support in patients without contraindications who remain unstable despite pharmacological therapy 4

Advanced Therapies

• Heart transplantation is clearly life-saving for those who are eligible for this therapy 6

Medications to Avoid

Certain medications should be avoided or used with extreme caution in heart failure: 4

• NSAIDs and COX-2 inhibitors 4
• Class I antiarrhythmic agents 4
• Calcium antagonists 4
• Tricyclic antidepressants 4
• Corticosteroids 4
• Combination of ACE inhibitors, ARBs, and mineralocorticoid receptor antagonists 4

Complications

Progressive Nature of Disease

Left ventricular dysfunction is generally a progressive process, even in the absence of a new identifiable insult to the heart, with the principal manifestation being cardiac remodeling. 2

• Most patients with heart failure do not show an uninterrupted and inexorable worsening of symptoms; instead, severity characteristically fluctuates 2
• Some patients may demonstrate remarkable recovery, sometimes associated with improvement in structural and functional abnormalities, usually with sustained drug therapy that should be continued indefinitely 2

Mortality

• Heart failure affects approximately 2% of the United States population, or some 4 million people 6
• The mortality rate for heart failure is worse than for many forms of cancer 6
• Pulmonary hypertension is the leading cause of death in patients with pulmonary arterial hypertension 4
• Patients with obesity hypoventilation syndrome and cor pulmonale have significantly increased perioperative mortality 1

Organ System Complications

• Heart failure affects virtually every organ system in the body 6
• Chronic kidney disease creates volume overload and neurohormonal activation, complicating management 3
• Pulmonary congestion leads to breathing difficulty 7
• Reduced delivery of blood to the brain causes dizziness 7
• Arrhythmias commonly develop 7

Nursing Considerations and Interventions

Monitoring Requirements

Continuously monitor heart rate, rhythm, blood pressure, and oxygen saturation for at least the first 24 hours in acute presentations. 4

• Monitor renal function, electrolytes, potassium, and sodium daily during IV therapy and when adjusting renin-angiotensin-aldosterone system antagonists 4
• Maintain oxygen saturation above 90% at all times 4
• Assess for signs of fluid overload: peripheral edema, pulmonary rales, jugular venous distension 2
• Monitor daily weights to assess fluid status 4

Medication Administration

• Start ACE inhibitors at low doses and titrate up to recommended maintenance dosages 4
• Administer loop diuretics cautiously, particularly in isolated right ventricular failure 4
• Monitor for hypotension when administering inotropes like milrinone 4
• Ensure stable oral diuretic regimen has been established for at least 48 hours before discharge 4

Discharge Planning

Before discharge, ensure the acute episode has resolved completely, congestion is absent, a stable oral diuretic regimen has been established for at least 48 hours, long-term disease-modifying therapy is optimized, and appropriate patient and family education has been provided. 4

Patient and Family Education

Lifestyle Modifications

Control sodium intake, particularly in patients with severe heart failure. 4

• Avoid excessive fluids only in severe heart failure 4
• Avoid excessive alcohol intake 4
• Encourage daily physical and leisure activities in stable patients to prevent muscle deconditioning 4
• Exercise training programs are recommended for stable NYHA class II-III patients 4

Medication Adherence

• Emphasize that sustained improvement is usually associated with drug therapy, and that therapy should be continued indefinitely 2
• Educate about the importance of taking medications as prescribed, even when feeling better 2
• Explain that changes in medications and diet can have favorable or adverse effects on functional capacity 2

Symptom Monitoring

• Teach patients to recognize signs of worsening heart failure: increased shortness of breath, weight gain, increased swelling 2
• Instruct patients to monitor daily weights and report sudden increases 4
• Educate about when to seek immediate medical attention: severe shortness of breath at rest, chest pain, severe swelling 2

Prevention Strategies

The real challenge is to devise strategies to prevent the occurrence of heart failure or interrupt its progress at a very early stage. 6

• Control risk factors: hypertension, diabetes, coronary artery disease 3
• Avoid cardiotoxic substances: excessive alcohol, illicit drugs 3
• Maintain healthy weight to reduce hemodynamic burden 3
• Treat sleep apnea if present 3