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Congestive heart failure

Summary

Congestive heart failure (CHF) is a clinical condition in which the heart is unable to pump enough blood to meet the metabolic needs of the body because of pathological changes in the myocardium. The three main causes of CHF are coronary artery disease (CAD), diabetes mellitus, and hypertension. These conditions cause ventricular dysfunction with low cardiac output, which results in blood congestion and poor systemic perfusion. CHF is classified as either left heart failure (LHF) or right heart failure (RHF), although biventricular (global) CHF is most commonly seen in clinical practice. LHF leads to pulmonary edema and consequent dyspnea, while RHF leads to systemic venous congestion that causes symptoms such as pitting edema, jugular venous distension, and hepatomegaly. Biventricular CHF manifests with clinical features of both RHF and LHF, as well as general symptoms such as tachycardia, fatigue, and nocturia. In rare cases, high-output CHF may occur as a result of conditions that increase cardiac output and thereby overwhelm the heart. CHF is diagnosed based on clinical presentation and requires an initial workup to assess the severity of the disease and determine the possible causes. Initial workup includes measurement of brain natriuretic peptide levels, chest x-ray, and an ECG. Management of CHF includes lifestyle modifications and treatment of associated conditions (e.g., hypertension) and comorbidities (e.g., anemia), along with pharmacologic agents that reduce the workload of the heart. Acute decompensated heart failure (ADHF) may occur as an exacerbation of CHF or be caused by an acute cardiac condition such as myocardial infarction. ADHF requires hospitalization and more intensive measures, such as hemodialysis.

Definition

Epidemiology

  • 1–2% of the population in the US (∼ 5.7 million individuals) has CHF. [3]
  • The incidence is higher among African Americans and Hispanics . [4]
  • Incidence increases with age: ∼ 10% of individuals > 60 years old are affected. [3]
  • Systolic heart disease is the most common form of CHF overall.

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Etiology of CHF [3][5]

Systolic dysfunction (reduced EF)

Diastolic dysfunction (preserved EF)

General causes
Specific causes
Further risk factors

The three major causes of heart failure are coronary artery disease, hypertension, and diabetes mellitus. Patients typically have multiple risk factors that contribute to the development of CHF.

Pathophysiology

Cardiac output, which is stroke volume times heart rate, is determined by three factors: preload, afterload, and ventricular contractility.

Underlying mechanism of reduced cardiac output

  1. Systolic ventricular dysfunction (most common) due to:
  2. Diastolic ventricular dysfunction due to:

Consequences of systolic and diastolic dysfunction

CHF is characterized by reduced cardiac output that results in venous congestion and poor systemic perfusion.

Compensation mechanisms

The compensation mechanisms are meant to maintain the cardiac output when stroke volume is reduced.

Clinical features

General features of heart failure

Clinical features of left-sided heart failure

Clinical features of right-sided heart failure

In clinical practice, biventricular heart failure with features of left and right heart failure is more likely than isolated failure of one ventricle.

Subtypes and variants

High-output heart failure

Stages

NYHA functional classification [14]

The NYHA (New York Heart Association) functional classification system is used to assess the patient's functional capacities (i.e., limitations of physical activity and symptoms) and has prognostic value.

NYHA class Characteristics
Class I
  • No limitations of physical activity
  • No symptoms of CHF
Class II
  • Slight limitations of moderate or prolonged physical activity (e.g., symptoms after climbing 2 flights of stairs or heavy lifting)
  • Comfortable at rest
Class III
  • Marked limitations of physical activity (e.g., symptoms during daily activities like dressing, walking across rooms)
  • Comfortable only at rest
Class IV
  • Confined to bed, discomfort during any form of physical activity
  • Symptoms at rest

American Heart Association (AHA) classification (2013) [14]

The AHA classification system classifies patients according to their stage of disease. It takes objective findings (patient history, diagnostic findings) as well as symptoms of CHF into account.

Stages Objective assessment Corresponding NYHA functional class
Stage A
Stage B
Stage C
  • Structural damage to the heart
  • Signs or symptoms of heart failure
  • NYHA I, II, III, IV
Stage D
  • Heart failure at its terminal stage

Diagnostics

Diagnostic approach [15]

  1. Medical history, including preexisting conditions and history of alcohol and recreational/prescribed drug use
  2. Initial evaluation involves a range of routine laboratory tests and a test for BNP level, ECG, and chest x-ray.
  3. Echocardiography is the gold standard for the diagnosis of CHF.
  4. Other procedures (e.g., exercise testing, angiography) may be required for further investigation.

Initial evaluation [15]

Laboratory analysis

  • Elevated BNP and NT-pro BNP
    • NT-pro BNP is a precursor of BNP that is used as a diagnostic marker of heart failure.
    • High levels of BNP in patients with classic symptoms of CHF confirm the diagnosis (high predictive index). [16]
BNP and NT-pro BNP levels in CHF
Markers CHF unlikely CHF likely
BNP (ng/L) [17] < 100 > 400
NT-pro BNP (ng/L) [10] < 300

> 450

Electrocardiogram (ECG)

ECG abnormalities in CHF are common, but are mostly nonspecific and nondiagnostic. [10]

Chest x-ray

Useful diagnostic tool to evaluate a patient with dyspnea and differentiate CHF from pulmonary disease

Transthoracic echocardiogram

Gold standard for evaluating patients with heart failure

Other tests

Treatment

General measures [15]

  • Lifestyle modifications
  • Patient education
    • Self-monitoring and symptom recognition
    • Daily weight check: A weight gain > 2 kg within 3 days requires a doctor consult.
    • Monitoring of potential medication side effects (e.g., hypotension caused by ACE inhibitors, hyperkalemia caused by aldosterone-antagonists, sensitivity to sunlight caused by amiodarone)
    • Travel restrictions [26][27]
      • Include most recent medical record when traveling
      • Advise against traveling to destinations with limited access to or inadequate health care
      • Patients with acute heart failure should restrain from traveling
  • Treatmenf of underlying conditions and contributing comorbidities

Pharmacologic treatment algorithm [28][29]

Drug NYHA stages Indications Contraindications and important side effects Benefits
I II III IV
First-line drugs
Diuretics (✓) (✓)
  • Improve symptoms
ACE inhibitors
  • Improve symptoms and prognosis
Beta blockers (✓)
Aldosterone antagonists (✓)
Second-line drugs
Ivabradine (✓) (✓) (✓)
  • Improves symptoms
  • Reduces hospitalization rate
Hydralazine plus nitrate [30] (✓) (✓)
  • Monitor for volume depletion and hypotension.
  • Improve symptoms
  • May improve prognosis

Digoxin [15]

(✓) (✓) (✓)
  • Improves symptoms
  • Reduces hospitalization rate
Angiotensin receptor-neprilysin inhibitor (✓) (✓) (✓) (✓)
  • Improves prognosis
  • Reduces hospitalization rate
Nesiritide (BNP derivative)

(✓): see “Indications” column for detailed information

Drugs that improve prognosis are beta blockers, ACE inhibitors, and aldosterone antagonists.

Drugs that improve symptoms are diuretics and digoxin (significantly reduce the number of hospitalizations).

Conducting regular blood tests to assess electrolyte levels (potassium and sodium) is mandatory if the patient is on diuretics.

Contraindicated drugs [32][33]

Avoid the concomitant use of calcium channel blockers with beta blockers.

Invasive procedures

Complications

We list the most important complications. The selection is not exhaustive.

Acute decompensated heart failure

Cardiac decompensation is the most common reason for hospital admissions and is the most important complication of congestive heart failure.

Etiology [39]

ADHF typically occurs in patients who have a history of CHF or other cardiac conditions in which an acute cause precipitates the deterioration of cardiac function.

Clinical features

  • Rapid exacerbation of CHF symptoms (see “Clinical features” section above)
  • Pulmonary congestion
    • Acute, severe dyspnea and orthopnea: worsen when supine
    • Cough: occasionally with frothing, blood-tinged sputum
    • Cyanosis
    • Rales accompanied by wheezing
    • Flash pulmonary edema: rapid, life-threatening accumulation of fluid associated with the risk of acute respiratory distress
  • Low cardiac output symptoms
    • Weakness, fatigue
    • Cold, clammy skin

Diagnostics [40]

To remember the radiologic signs of pulmonary congestion think of “ABCDE”: Alveolar edema (bat wings), Kerley B lines (interstitial edema), Cardiomegaly, Dilated prominent pulmonary vessels, and Effusions.

Differential diagnosis of pulmonary edema and respiratory distress [43]

Treatment

Beta blockers must be used cautiously in decompensated heart failure.

To remember the most important components of ADHF management, think “LMNOP”: Lasix (furosemide), Morphine, Nitrates, Oxygen, Position (with elevated upper body).

Acute management checklist for heart failure exacerbation [44][45][46][47]

Hemodynamically stable patients

Beta blocker therapy should NOT be initiated at the time of presentation in patients who are not already taking a beta blocker.

Hemodynamically unstable patients (i.e.,