Etiology

Causes and precipitating factors in acute heart failure are:

  • Decompensation of pre-existing chronic heart failure

  • Acute coronary syndrome

  • Hypertensive crisis

  • Acute arrhythmia

  • Severe valvular regurgitation

  • Severe aortic or mitral valve stenosis

  • Acute severe myocarditis

  • Cardiac tamponade

  • Aortic dissection

  • Postpartum cardiomyopathy

  • Lack of adherence to medical treatment

  • Volume overload

  • Infections

  • Severe brain insult

  • After major surgery

  • Reduction of renal function

  • Drug abuse

  • Pheochromocytoma

  • High output syndromes

    • Septicemia

    • Thyrotoxic crisis

    • Anemia

    • Shunt syndromes.

The most common concurrent conditions present in patients with acute heart failure are coronary artery disease, hypertension, diabetes mellitus, atrial fibrillation, and renal insufficiency.[1]​​[9]

Pathophysiology

During an episode of acute heart failure, the majority of patients will have evidence of volume overload with pulmonary and/or venous congestion. Hemodynamic measurements in these cases usually show increased right- and left-sided ventricular filling pressures with depressed cardiac index and cardiac output. However, if there is associated infection, the cardiac output may be normal or, in some cases, increased.

Activation of the sympathetic nervous system causes tachycardia, increased myocardial contractility, increased myocardial oxygen consumption, peripheral vasoconstriction, and activation of renin-angiotensin system with salt and water retention. There is also activation of vasoconstrictor neurohormones, which leads to sodium and fluid retention, increased myocardial wall stress, and decreased renal perfusion.[10]

If the condition is not treated effectively, the myocardium becomes unable to maintain a cardiac output sufficient to meet the demands of the peripheral circulation. In order for patients with acute heart failure to respond quickly to treatment, the increased myocardial stress must be reversed; for example, correction of acute severe hypertension. This is particularly important in acute heart failure caused by ischemia, as a dysfunctional myocardium can return to normal when appropriately treated.

Classification

Clinical presentations

Patients with acute heart failure may present with a spectrum of conditions ranging from gradually progressive dyspnea to acute pulmonary edema and cardiogenic shock.​ Broadly, they can be subclassified into groups according to the principal cause leading to acute heart failure (e.g., patients with acute coronary syndrome, accelerated hypertension, rapid arrhythmias or heart block, acute mechanical cause, valvular dysfunction, acute right heart failure due to massive pulmonary embolism, and acute on chronic heart failure).

The European Society of Cardiology describes four major clinical presentations, with possible overlaps between them:[1]

  1. Acute decompensated heart failure

  2. Acute pulmonary edema

  3. Isolated right ventricular failure

  4. Cardiogenic shock.

Clinical classification of acute heart failure[3]

For simplification these patients can be classified into three main groups:

1. Hypertensive acute heart failure (acute de novo heart failure or vascular failure)

  • Symptoms develop rapidly against a background of hypertension with increased sympathetic tone and neurohormonal activations.

  • Left ventricular ejection fraction (LVEF) is usually preserved and there are clinical and radiologic findings of pulmonary congestion, usually without signs of systemic congestion; for example, peripheral edema.

  • Response to therapy is rapid.

2. Normotensive acute heart failure (acutely decompensated chronic heart failure)

  • History of progressive worsening of chronic heart failure.

  • BP is usually normal and symptoms and signs develop gradually with both systemic and pulmonary congestion.

  • LVEF is usually reduced.

3. Hypotensive acute heart failure

  • Presents with symptoms and signs of hypotension, organ hypoperfusion, and cardiogenic shock.

Types of heart failure

Traditionally heart failure is classified as:

  • Systolic - associated with LV dysfunction and characterized by cardiomegaly, third heart sound, and volume overload with pulmonary congestion. LVEF is decreased

  • Diastolic - typically associated with normal cardiac size, hypertension, pulmonary congestion, and a fourth heart sound. LVEF is preserved.

Based on measurement of LVEF, heart failure is classified as:[1][2]

  • Heart failure with reduced ejection fraction (HFrEF) - symptoms and signs and LVEF ≤40%

    • A subgroup of HFrEF can be further classified as heart failure with improved ejection fraction (HFimpEF) if a previous ejection fraction ≤40% has improved to >40% after follow-up measurement.[2]

  • Heart failure with mildly reduced ejection fraction (HFmrEF) - symptoms and signs and LVEF 41% to 49%

  • Heart failure with preserved ejection fraction (HFpEF) - symptoms and signs and LVEF ≥50%.

    • Evidence of structural heart disease may be used to further support the diagnosis of HFpEF.[2]

The criteria for diagnosis of HFmrEF and HFpEF require evidence of spontaneous (at rest) or provokable (e.g., during exercise, fluid challenge) increased LV filling pressures.[1][2] This may be fulfilled by elevated natriuretic peptides, noninvasive measures (e.g., echocardiographic diastolic parameters), or by invasive hemodynamic measurement.[2]

Use of this content is subject to our disclaimer