Heart Failure

Introduction

Heart failure has a broad definition but the basis of the disease process is that the cardiac output is insufficient to meet the metabolic demands of the body.

  • It results from the impairment of the ventricle to fill with or eject blood. 
  • Heart failure is caused by ventricular pump dysfunction, overload of volume (preload), or by overload of pressure (afterload).
  • The majority of pediatric heart failure can be categorized as:
    • Excessive preload
    • Increased afterload
    • Abnormal rhythm leading to decreased contractility

Epidemiology

  • Pediatric heart failure is estimated to affect 12,000 to 35,000 individuals under the age of 19 years in the United States. 
  • In the United States, heart failure-related hospitalization is increasing, and accounts for approximately 14,000 hospitalizations in children.
  • Pediatric heart failure is the most common reason that infants and children who have heart disease receive medial therapy and accounts for at least 50% of referrals for pediatric heart transplantation.  
  • The largest pediatric heart failure population comes from children born with congenital malformations.  
  • However, the etiology of heart failure is diverse due to the numerous underlying cardiac manifestations and presentations that can lead to a diagnosis of heart failure.

Pathophysiology

The etiology of pediatric heart failure can primarily be divided into three large categories with a variety of disease process fitting in either category with some overlay.

The three categories are:

  1. Ventricular pump dysfunction,
  2. Volume overload (increased preload)
  3. Pessure overload (increased afterload)

Ventricular dysfunction occurs when there is decreased contractility of the ventricles that causes reduced ejection of blood from the ventricle.

  • Most children that develop ventricular dysfunction are born with structurally normal hearts.
  • There are several cardiac and noncardiac etiologies that can lead to ventricular dysfunction. 
  • However, cardiomyopathy (dilated, hypertrophic, constrictive, or restrictive) is the most common cause of heart failure in children with a structurally normal heart.
  • Heart failure is the presenting feature in most of these patients.


Structural categories of cardiomyopathy.
https://en.wikipedia.org/wiki/Cardiomyopathy

Volume overload or increased preload that leads to heart failure is caused primarily by left-to-right systolic shunts.

  • This causes a volume load on the left side of the heart to create preload stress.
    • Valvular regurgitation lesions, either acquired or congenital, also volume overloads the heart.
    • These most commonly are mitral or aortic regurgitation.

Pressure overload or increased afterload is due to congenital heart disease with severe ventricular outflow obstruction that limits ejection of blood from the heart, resulting in inadequate cardiac output. 

  • Left heart obstructive lesions such as mitral stenosis, aortic stenosis, and coarctation of the aorta induce acute heart failure and/or lethal arrhythmias, which cause severe afterload stress.

Clinical Manifestations

Due to pediatric heart failure having several etiologies, it has a variety of age- dependent clinical presentations.

Infants

  • Feeding difficulties occur due to dyspnea and increased fatigability, tachypnea, irritability, and poor weight gain. 
  • They ultimately are lead to failure to thrive diagnosis.  
  • Upon physical exam you may find:
    • Mild-severe retractions
    • Tachypnea
    • Grunting
    • Tachycardia
    • S3 or S4 heart sound (gallop rhythm)
    • Hepatomegaly.

Young Children

  • Symptoms may be mistaken for common childhood illness such as gastroenteritis or asthma. 
  • This is due to presentation of abdominal pain, poor appetite, easy fatigability, chronic cough, or wheezing. 

Older Children

  • Present with more “adult like” symptoms such as:
    • Exercise intolerance
    • Somnolence
    • Cough with crackles and
    • Gallop rhythm (S3, S4).

Therapy

The management of pediatric heart failure is dependent on its etiology and severity. The primary therapeutic goal is to treat the underlying cause.

  • Therapeutic goals are to decrease symptoms, morbidity, and hospitalizations and to slow progression of heart failure.
    • Treatment of noncardiac causes of heart failure such as anemia or endocrine disorders as well as timely referral for surgical corrections can prevent or limit the staging of heart failure.

Surgical or catheter-based interventions

  • Used to correct structural defects such as shunts or valvular defects causing either volume or pressure overload, and preserved ventricular function.

Medical management

  • Used to maximize cardiac output and tissue perfusion and is primarily used in patients with ventricular pump dysfunction.
    • These goals are accomplished by reducing the amount of pressure the heart needs to generate to eject blood leading to reduced afterload.
    • Other medical management involves reducing preload or the overfilling of the heart. 
    • This leads to more treatments needing to “rest” the heart such as vasodilators than inotropic agents that increase myocardial oxygen consumption.
    • Below, there is a table full of the medical principles in management of heart failure.
      • Diuretics, digoxin, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin II receptor blockers (ARBs) are used in improving symptoms.
      • Beta-blockers, ACE inhibitors, and ARBs have been documented to prolong patient survival, improve left ventricular function, and reverse left ventricular dilation. 
  • The ultimate therapy after all medical interventions have failed is a cardiac transplantation.

References

  1. American Academy of Pediatrics
  2. Boucek MM, Edwards LB, Keck BM, Trulock EP, Taylor DO, Hertz MI. Registry for the International Society for Heart and Lung Transplantation: seventh official pediatric report–2004. J Heart Lung Transplant. 2004;23:933–947
  3. Hsu DT, Pearson GD. Heart failure in Children: part I: history, etiology, and pathophysiology. Circ Heart Fail 2009; 2:63
  4. Kay JD, Colan SD, Graham TP Jr. Congestive heart failure in pediatric patients. Am Heart J. 2001;142:923–928

  5. Madriago E, Silberbach M. Heart Failure in Infants and Children. Pediatrics in Review Vol. 31 No.1 January 2010

 

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