• Clinical science

Acyanotic congenital heart defects

Summary


Acyanotic heart defects are congenital cardiac malformations that affect the atrial or ventricular walls, heart valves, or large blood vessels. Common causes include genetic defects (e.g., trisomies), maternal infections (e.g., rubella), or maternal consumption of drugs or alcohol during pregnancy. Acyanotic heart defects are characterized pathophysiologically by a left-to-right shunt, which causes pulmonary hypertension and right heart hypertrophy. The symptoms depend on the extent of the malformation and the resulting impairment of cardiac function. Infants may be asymptomatic or present with exercise intolerance, failure to thrive, and symptoms of heart failure. Characteristic heart murmurs are important clues for establishing the diagnosis, which is typically confirmed by visualizing the defect on echocardiography. A chest x-ray, MRI, or cardiac catheterization may also be required to determine the indications for surgery and plan the procedure. Acyanotic heart defects requiring treatment are repaired via catheter procedures or surgery. Supportive medical therapy is needed in cases of heart failure (e.g., diuretics, inotropic agents) or if surgery cannot be performed (e.g., prostaglandin). Common complications include arrhythmias, embolisms, and infective endocarditis, especially if treatment is delayed.

Pathophysiology

General pathophysiological processes

Untreated left-to-right shunts (acyanotic heart defects) may progress to right-to-left shunts (cyanotic defects) if right ventricular pressure exceeds left ventricular pressure due to pulmonary arterial hypertension (Eisenmenger reaction).

References:[1]

Overview of acyanotic congenital heart defects

General clinical features

General treatment concepts

Ductal dependent CHDs
PDA needed for systemic circulation PDA needed for pulmonary circulation

Critical aortic valve stenosis

Critical pulmonary valve stenosis

Coarctation of the aorta Tetralogy of Fallot
Transposition of the great arteries Tricuspid atresia
Hypoplastic left heart syndrome

The “3 Ds” of acyanotic CHDs: VSD, ASD, PDA.
References:[2][3][4][5][6][7][8][9]

Atrial septal defect (ASD)

Epidemiology

Etiology

Pathophysiology

Clinical findings

  • Depend on defect size and shunt volume
    • Small defects: usually asymptomatic
    • Large defects
      • See “Nonspecific symptoms” and “Heart failure” in the overview above.
      • Palpitations
      • ASDs typically manifest with advancing age.
  • Auscultation

Diagnostics

Treatment

  • In childhood, spontaneous closure may occur.
  • Patch repair
    • Indicated in symptomatic children with significant left-to-right shunt
    • Surgical or via percutaneous transcatheter procedure

Complications

References:[2][10][11][12][13][14][15]

Ventricular septal defect (VSD)

Epidemiology

  • The most common congenital heart defect (4/1000 live births)
  • Occurs as an isolated heart defect or in combination with others

Etiology

Pathophysiology

Clinical findings

  • Small defects: usually asymptomatic
  • Medium-sized or large defects
    • Lead to cardiac failure in the first 2–3 months of life
      • Some VSDs can present after the first weeks of life because pulmonary vascular resistance (PVR) is high at birth and decreases thereafter. PVR↓ right ventricular pressure → left-to-right shunt → presence of symptoms
    • See also “Nonspecific symptoms” and “Heart failure” in the overview section above.
  • Palpation: Hyperdynamic precordium may be detected in hemodynamically relevant defects.
  • Auscultatory findings

Diagnostics

Treatment

  • Small VSDs: rarely require surgical interventions → small to moderate defects often heal spontaneously; follow-up echocardiography recommended
  • Symptomatic and large VSDs

Complications

References:[2][3][16][17][18][19]

Patent foramen ovale (PFO)

Definition

  • Persistence of the foramen ovale beyond 1 year of age

Epidemiology

Pathophysiology

  • The foramen ovale in the atrial septum does not close after birth. mild left-to-right shunt
  • A shunt reversal may be induced by certain maneuvers that induce an increase in right atrial pressure (e.g., Valsalva maneuver, coughing).

Clinical findings

  • Patients are usually asymptomatic until complications occur (see below).

Diagnostics

Complications

Treatment

  • Asymptomatic PFO: The majority of cases do not require any treatment.
  • Ischemic infarction in patients with confirmed PFO; : medical therapy with antiplatelet agents; or anticoagulation; and surgical or percutaneous closure of the defect

References:[20][21]

Patent ductus arteriosus (PDA)

Definition

Epidemiology

  • Sex: > (2:1)

Etiology

Pathophysiology

Clinical features

Diagnostics

Treatment

Complications

References:[2][3][22][23][24][25]

Coarctation of the aorta

Definition

Epidemiology

Etiology

Pathophysiology

  • Genetic defects and/or intrauterine ischemiamedial thickening and intimal hyperplasia form a ridge encircling the aortic lumen → narrowing of the aorta → ↑ flow proximal and ↓ flow distal to the narrowing
  • Compensatory mechanisms
    • Myocardial hypertrophy and collateral blood flow (e.g., intercostal vessels , scapular vessels) develop in cases of discrete stenosis to compensate for the left ventricular outflow tract obstruction (common) → onset of symptoms usually later in childhood
    • In long segment stenosis, there is no time for development of compensatory mechanisms → closure of PDA after birth → left ventricular pressure and volume overload → hypoperfusion of organs and extremities distal to the stenosis, heart failure, cardiogenic shock

Clinical findings

Diagnostics

Treatment

Complications

References:[2][26][27][28]

Endocardial cushion defect

Definition

Etiology

Pathophysiology

  • Complete form (ASD and VSD) → atrial and ventricular left-to-right shunt → excessive pulmonary blood flow and biventricular volume overloadpulmonary hypertension and heart failure
  • Partial form (only ASD) → atrial left-to-right shunt → symptoms may remain minimal until adulthood
  • In both forms: abnormal AV valveAV valve regurgitation → in severe cases, in utero heart failure (nonimmune hydrops fetalis)

Clinical features

  • Complete form: See “Nonspecific symptoms” and “Heart failure” in the overview section above.
  • Partial form: See “Clinical features” of ASD.
  • Heart murmurs according to underlying characteristic septal and valvular defects

Diagnostics

Treatment

  • Improve cardiac function in patients with heart failure (see treatment of “Heart failure symptoms” in the overview section above)
  • Surgical repair

References:[3][29][30]