• Clinical science

Congestive heart failure

Abstract

Congestive heart failure (CHF) is a clinical syndrome in which the heart is unable to pump enough blood to meet the metabolic needs of the body. The three main causes of heart failure are coronary heart disease, diabetes mellitus, and hypertension. These conditions cause ventricular dysfunction with low cardiac output, which in turn results in congestion of blood (backward failure) and poor systemic perfusion (forward failure). Heart failure is commonly classified as left-sided and right-sided heart failure, although biventricular heart failure is most commonly seen in clinical practice. Left-sided heart failure results in pulmonary edema and associated dyspnea, while right-sided heart failure induces systemic venous congestion that causes symptoms such as pitting edema and hepatomegaly. Biventricular (global) HF presents with clinical features of both left-sided and right-sided failure, as well as general symptoms such as tachycardia, fatigue, and nocturia. In rare cases, high-output HF may occur as a result of conditions with an increased (rather than decreased) cardiac output, which overwhelms the heart. Acute decompensated heart failure (ADHF) may occur as an exacerbation of CHF or be due to an acute cardiac condition such as myocardial infarction. The diagnosis of CHF is based on clinical presentation and requires an initial workup to assess disease severity and possible causes. The initial workup includes measurement of brain natriuretic peptide levels, chest x-ray, and ECG. Management of CHF includes lifestyle modifications, treatment of associated conditions (e.g., hypertension) and comorbidities (e.g., anemia) that would otherwise worsen the symptoms of HF, and additional pharmacologic agents that reduce the workload of the heart. ADHF requires hospitalization and more intensive measures, such as hemodialysis.

Definition

References:[1]

Epidemiology

  • Prevalence
    • 1–2% of the population (∼ 5.7 million individuals in the US have heart failure)
      • The incidence is higher among African Americans, Hispanics, and Native Americans
    • Increases with age; ∼ 10% of individuals > 60 years old affected
    • Systolic heart disease is the most common form of HF overall.

References:[2][3]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Systolic dysfunction Diastolic dysfunction
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 HF!
References:[4][5][2][3][6]

Pathophysiology

General physiological concepts

Pathomechanism

CHF is characterized by reduced cardiac output that results in venous congestion and poor systemic perfusion!
References:[4][7]

Clinical features

General features of heart failure
Clinical features of left-sided heart failure Clinical features of right-sided heart failure
Pulmonary symptoms dominate Symptoms of fluid retention (backward failure) dominate
  • Forward failure: cool extremities, cerebral and renal dysfunction, sweating (NYHA IV)
  • Forward failure less pronounced

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

References:[4][5][8][9][10][11]

Subtypes and variants

High-output heart failure

References:[5][12][2][13]

Stages

NYHA Functional Classification

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

NYHA class Characteristics

Physical exercise capacity or functional capacity measured in Watts

Cardiac output (CO)
Class I

No limitations of physical activity; no symptoms of HF

> 100 watts Normal even under stress
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 = 100 watts Adequate with low amount of stress
Class III Marked limitations of physical activity (symptoms during daily activities like dressing, walking across rooms); comfortable only at rest Up to 50 watts Reduced under stress
Class IV Confined to bed, discomfort during any form of physical activity; symptoms present at rest No physical activity possible Reduced at rest

American Heart Association (AHA) Classification (2013)

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 HF into account.

Stages Objective assessment Corresponding NYHA functional class
Stage A

High risk of developing heart failure (e.g., pre-existing arterial hypertension, CAD, diabetes mellitus); no structural cardiac changes

No corresponding NYHA class
Stage B Structural damage to the heart (e.g., infarct scars, dilatation, hypertrophy), without signs or symptoms of heart failure NYHA I
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 NYHA IV

References:[8][14][15][16][17][18]

Diagnostics

Heart failure is primarily a clinical diagnosis. Laboratory tests and imaging tests, including a chest x-ray and echocardiogram, are useful for evaluating the severity and cause of the condition.

Diagnostic approach

  1. Medical history, including pre-existing conditions and history of alcohol and recreational or prescribed drug abuse
  2. Initial evaluation involves laboratory tests for BNP level, ECG, and chest x-ray.
  3. Echocardiography is the gold standard tool for assessing cardiac morphology and function, as well as investigating the underlying cause of HF.
  4. Other procedures (exercise testing, angiography) may be required for further investigation.

Initial evaluation

Laboratory analysis

  • Elevated BNP and NT-pro BNP
    • High levels of BNP in patients with classic symptoms of HF confirm the diagnosis (high predictive index).
HF unlikely HF likely
BNP (pg/mL) < 100 > 400
NT-pro BNP (pg/mL) < 300

> 450 (patients aged < 50 years)
> 900 (patients aged 50–75 years)

> 1800 (patients aged > 75 years)

Electrocardiogram (ECG)

Chest x-ray

  • Useful diagnostic tool to evaluate a patient with dyspnea and differentiate HF from pulmonary disease
  • Signs of cardiomegaly
    • Cardiac-to-thoracic width ratio > 0.5
    • Boot-shaped heart on PA view (due to left ventricular enlargement)
  • Assess pulmonary congestion (See X-ray findings in pulmonary congestion in “Acute decompensated heart failure” below.)

Transthoracic echocardiogram

  • Gold standard for evaluating patients with heart failure
  • Assess ventricular function and hemodynamics
    • Atrial and ventricular size
    • Interventricular septum thickness: > 11 mm (normal 6–11 mm) indicates cardiac hypertrophy
    • Systolic function: left ventricular ejection fraction
      • Normal EF: > 55%
      • Slightly reduced EF: 45–54%
      • Reduced EF: 30–44%
      • Extremely reduced EF: < 30%
    • Diastolic function (diastolic filling, ventricle dilation)
  • Investigate etiology
    • Valvular heart disease
    • Wall motion abnormalities (indicate prior or acute MI)
    • Right ventricular strain
    • Tissue doppler: PCWP in left-sided heart failure

Ultrasound

    • Ultrasound of pleural cavities: sensitive method for detecting pleural effusion (CT may be better for detecting small amounts of fluid)
    • Ultrasound of large blood vessels
      • The volume status of the inferior vena cava is used to assess intravascular volume
      • Normal IVC diameter is < 2 cm. It is more important to determine its variation during respiration and the dynamics of the volume status after initiating diuretic treatment, rather than comparing it with normal values.
    • Ultrasound of the abdomen

Further tests

References:[4][8][2][19][9][20][21]

Treatment

General measures

  • Lifestyle modifications
  • Patient education
    • Self-monitoring and symptom recognition
    • Daily weight check
      • Weight gain > 2 kg within 3 days: consult the doctor
    • Monitoring potential side effects (e.g., hypotension caused by ACE inhibitors, hyperkalemia caused by aldosterone-antagonists, sensitivity to sunlight caused by amiodarone)
    • Travel restrictions: Include most recent medical record when traveling. Advise against traveling to destinations with limited access to or inadequate health care.
    • Patients suffering from symptoms of depression and cognitive dysfunction should also be offered neurological and psychiatric treatment.
  • Treat any underlying conditions and contributing comorbidities.

Pharmacologic treatment algorithm

Drug NYHA stages Indications Contraindications and important side effects Benefits
I II III IV
First-line drugs
Diuretics (loop diuretics and thiazide diuretics) (✓) (✓)
  • Monitor for hypokalemia and hyponatremia, weight gain, and volume status
  • Improve symptoms
ACE inhibitors
  • Monitor for hyperkalemia, hypotension, creatinine (renal impairment)
  • Improve symptoms and prognosis
Beta blockers (✓)
Aldosterone antagonists (✓)
  • Monitor for hyperkalemia
Second-line drugs
Ivabradine (✓) (✓) (✓)
  • Contraindicated in severe bradycardia
  • Improves symptoms
  • Reduces hospitalization rate
Hydralazine plus nitrate (✓) (✓)
  • If EF < 40%; particularly beneficial for African-american patients
  • Alternative if ACE inhibitors and AT1 blockers are not tolerated
  • Monitor for volume depletion and hypotension
  • Improves symptoms; and may improve prognosis
Digoxin (✓) (✓) (✓)
  • Improves symptoms
  • Reduces hospitalization rate
ARNI (angiotensin receptor-neprilysin inhibitor)
  • Persistent or worsening symptoms despite adequate treatment regimen with first-line drugs
  • Administered as combination valsartan-sacubitril
  • Improves prognosis
Nesiritide

Drugs that improve prognosis: beta blockers, ACE inhibitors, and aldosterone antagonists!

Drugs that improve symptoms: 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

Invasive procedures

  • Implantable cardiac defibrillator: (ICD): prevents sudden cardiac death
  • Cardiac resynchronization therapy: (CRT): improves cardiac function
    • Indications: HF with EF < 35% and left bundle branch block (intraventricular conduction delay with QRS > 120–150 ms)
    • Can be combined with an ICD
  • Coronary revascularization with PCTA or bypass surgery may be indicated if CHD is present
  • Valvular surgery if valvular heart defects are present
  • Ventricular assist devices: (left-ventricular assist devices, right-ventricular assist devices, or biventricular assist devices): a device that may be implanted to support ventricular function; may be indicated for temporary or long-term support (e.g., to bridge time until transplantation) of decompensated HF
  • Cardiac transplantation: for patients with end-stage HF (NYHA class IV), ejection fraction < 20%, and no other viable treatment options

References:[2][22][14][23][24][25][26][27]

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 chronic heart failure.

Etiology

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

Clinical features

  • Rapid exacerbation of symptoms of HF (see symptoms of left heart failure and symptoms of right heart failure)
  • Pulmonary edema with:
    • Acute, severe dyspnea and orthopnea
    • Cough (occasionally with frothing, blood-tinged sputum)
    • Cyanosis
    • Auscultation of the lungs: rales accompanied by wheezing
    • Flash pulmonary edema: rapid, life-threatening accumulation of fluid associated with the risk of acute respiratory distress
  • Weakness, fatigue, and cold, clammy skin

Diagnostics

Differential diagnosis of pulmonary edema and respiratory distress

Treatment

Treatment of acute pulmonary congestion with LMNOP: Lasix® (furosemide), morphine, nitrates, oxygen, (upright) position.
Beta blockers must be used cautiously in decompensated heart failure!
References:[4][5][5][8][28][2][29][30][31][32]

Cardiorenal syndrome

Cardiorenal syndrome is a complication of acute and chronic HF.

  • Definition: : a complex syndrome in which renal function progressively declines as a result of severe cardiac dysfunction; occurs in ∼ 20–30% of cases of acute decompensated HF
  • Pathophysiology
    • Cardiac forward failure → renal hypoperfusion → prerenal kidney failure
    • Cardiac backward failure → systemic venous congestion → renal venous congestion → decreased transglomerular pressure gradient → GFR → worsening kidney function
    • RAAS activation → salt and fluid retention, hypertensionhypertensive nephropathy
  • Diagnosis: GFR, creatinine that cannot be explained by underlying kidney disease
  • Treatment: treat heart failure; manage renal failure (see treatment of acute renal injury)
  • Prognosis: : HF with reduced GFR is associated with a poor prognosis; mortality increases by ∼ 15% for every 10 mL/min reduction in estimated GFR.

References:[33][34][35]

Prognosis

Prognosis estimates vary depending on patient characeristics, type and severity of heart disease, medication regimens, and lifestyle changes. Prognosis for patients with preserved EFs may be similar or improved compared to those with decreased EFs.

1-year survival according to NYHA stage:

  • Stage I: ∼ 95%
  • Stage II: ∼ 85%
  • Stage III: ∼ 85%
  • Stage IV: ∼ 35%

References:[17]