Acyanotic congenital heart defects

Last updated: October 27, 2023

Summarytoggle arrow icon

Acyanotic congenital heart defects (CHDs) are 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 use of drugs or alcohol during pregnancy. Acyanotic heart defects are pathophysiologically characterized 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. Chest x-ray, MRI, or cardiac catheterization may also be required to determine indications for surgery and plan the procedure. Acyanotic heart defects requiring treatment are repaired via catheter procedures or surgery. Supportive medical therapy is required in cases of heart failure (e.g., diuretics, inotropic agents) or if surgery cannot be performed (e.g., prostaglandin). Complications are more likely the longer treatment is delayed, and include arrhythmias, embolisms, infective endocarditis, and reversal of shunt physiology (i.e., Eisenmenger syndrome).

Overviewtoggle arrow icon

Common acyanotic CHDs

Overview of acyanotic CHDs [1][2][3]
Description Associated conditions and risk factors Management
Atrial septal defect (ASD)
  • Small ASDs: observation
  • Significant shunting: closure (surgical or percutaneous)
Ventricular septal defect (VSD) [8]
  • Most small VSDs: observation [8]
  • Large VSDs and symptomatic patients: surgical closure
Atrioventricular septal defect (AVSD)
Patent foramen ovale (PFO) [10]
  • Persistence of the foramen ovale cordis after 1 year of age
  • Often asymptomatic
  • In adults, may precipitate embolic strokes or be diagnosed incidentally
  • Asymptomatic PFO: no treatment
  • Antithrombotics and PFO closure may be indicated after an embolic event.
Patent ductus arteriosus (PDA) [11][12]
Coarctation of the aorta [15]
Pulmonary valve stenosis [17][18]

The “3 Ds” of acyanotic CHDs (in order of frequency): VSD, ASD, PDA

Pathogenesis [19]


  • Congenital heart defects (CHDs) are caused by the disruption of the normal sequence of cardiac morphogenesis.
  • CHDs may lead to the formation of pathological connections (shunts) between the right and left heart chambers, allowing blood to flow along the pressure gradient from high pressure to low pressure.
  • The shunts are classified according to the direction of the blood flow as either left-to-right or right-to-left.

Shunt types

Left-to-Right shunts = LateR cyanosis. Right-to-Left shunts = eaRLy cyanosis.

General clinical features

For specific features, see “Clinical features” in the respective subsections.

Nonspecific findings

Heart failure

Medical management of acyanotic CHDs [3]

Cardiac septal defectstoggle arrow icon

Comparison of common features of VSD and ASD [3]
Ventricular septum defect (VSD) [8] Atrial septum defect (ASD)
  • Third most common CHD [22]
Clinical features Small defect
  • Usually asymptomatic
Medium-sized or large defect
ECG Small defect
  • Normal ECG findings
Medium-sized or large defect
  • Pathological left-to-right blood flow
  • Interatrial communication
Chest x-ray
  • Enlarged right atrium and ventricle
  • Enhanced pulmonary vasculature

Atrial septal defect (ASD)toggle arrow icon


  • A defect in the atrial wall that may result from impaired growth or excessive resorption of the atrial septum

Epidemiology [3]



Clinical features [3]


  • Depend on defect size and shunt volume
  • Small defects: usually asymptomatic
  • Medium-sized to large defects
    • Symptoms can vary from asymptomatic to heart failure.
    • ASDs typically manifest with advancing age. [3]
  • See “General clinical features” above.

Auscultation [3]

Diagnostics [23]

Treatment [3]

Up to 40% of ASDs spontaneously close by the age of 5 years. [25]

Complications [26]

Ventricular septal defect (VSD)toggle arrow icon





Clinical features [3][8]


  • Small defects: usually asymptomatic
  • Medium-sized or large defects
  • Hyperdynamic precordium may be detected in hemodynamically relevant defects.


Symptoms of heart failure in children with VSD only develop when PVR decreases to adult levels and thus allows left-to-right shunting to occur.

Diagnostics [8]

Treatment [3][8]

VSD closure results in lower right ventricular and left atrial pressures and higher left ventricular pressures than preclosure values. [28]

VSD closure is contraindicated in patients with Eisenmenger syndrome. [3]


Atrioventricular septal defect (AVSD)toggle arrow icon

Definition [3]

A defect of atrioventricular valves (i.e., mitral and tricuspid valves) as well as the atrial and/or ventricular septum; previously referred to as endocardial cushion defects


Pathophysiology [3]

Clinical features [3]

Diagnostics [33]

Treatment [3][14][33]

  • All patients: Provide medical management of acyanotic CHDs as needed.
  • Surgical management: patch closure and AV valve reconstruction; generally indicated unless Eisenmenger syndrome has developed
    • Complete form: generally between 3–6 months of age
    • Partial form: generally between 2–4 years of age
    • Older patients: elective procedure

Patent foramen ovale (PFO)toggle arrow icon


  • A variant of cardiac anatomy in which the foramen ovale remains patent beyond 1 year of age


  • Prevalence: ∼25% of the general population [34]



ASD = Septal tissue Deficiency. PFO = enough tissue, but Problems with Fusion.

Clinical features

  • Affected individuals are usually asymptomatic until complications occur.

Diagnostics [35]

PFOs are sometimes an incidental finding during procedures (e.g., PCI, cardiac surgery) or must be evaluated for after an embolic event (e.g., ischemic stroke).

Treatment [10]

PFO is one of many possible causes of stroke. Reducing subsequent stroke risk should include the evaluation of other potential causes (e.g., arrhythmia, hypercoagulability, endocarditis). [10]

Complications [36]

Patent ductus arteriosus (PDA)toggle arrow icon





Clinical features



  • Small PDA: A murmur is sometimes heard incidentally during routine primary care visits.
  • Large PDA: Machinery murmur: loud continuous murmur heard best in the left infraclavicular region; and loudest at S2

PDA comes with Prolonged Deafening Auscultation findings.

Diagnostics [11][39]

Treatment [11][12]

Management of PDA is complex and based on the specific PDA (e.g., size of left-to-right shunt) and patient characteristics (e.g., weight, age).

PDA closure [14]

Pharmacological closure in premature infants [3]

The management of premature infants with a PDA is complex and requires a multidisciplinary team including a neonatal intensivist and pediatric cardiologist.

PDA closure is contraindicated if the PDA is required for survival, e.g., ductal-dependent CHDs. Initiate a prostaglandin E1 infusion to keep the ductus arteriosus patent until definitive treatment can be performed. [40]

Complications [38]

Coarctation of the aortatoggle arrow icon


Epidemiology [41]

Etiology [2]



Pathophysiology [1][2]

Clinical features [2]



Diagnostics [3]

Treatment [1][15]


Pulmonary valve stenosistoggle arrow icon



  • Relatively common in the general population (∼10% of all CHDs) [3]
  • Usually congenital (rarely acquired )


Clinical features

Diagnostics [17]

Treatment [17][18]

Eisenmenger syndrometoggle arrow icon

Description [3][48]

  • A complication of acyanotic heart disease in which the shunt reverses over time and cyanotic heart disease develops
  • Can occur at any age, but usually develops during late stages of CHDs

Etiology [3]

Eisenmenger syndrome may develop with any cardiac defect with a left-to-right shunt, but common defects include:

Pathogenesis [3][48]

  1. Left-to-right shunt prolonged pulmonary hypertension reactive constriction with permanent remodeling of pulmonary vessels → irreversible pulmonary hypertension
  2. Pulmonary hypertensionRV hypertrophy → increased RV pressure
  3. RV pressure exceeds LV pressure shunt reversal (development of right-to-left shunt) cyanosis; , digital clubbing, and polycythemia

Clinical features [3]

Children at risk of Eisenmenger syndrome are often minimally symptomatic; symptoms worsen with age and with increasing pulmonary resistance.

Diagnosis [3]

Treatment [3]

Treatment should be guided by specialists in pulmonary hypertension and pediatric cardiology; treatment includes:

Referencestoggle arrow icon

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