Congenital Heart Disease

A significant proportion of patients with congenital heart disease (CHD), in partic- ular those with relevant systemic-to-pulmonary shunts, will develop PAH if left untreated. Persistent exposure of the pulmonary vasculature to increased blood flow, as well as increased pressure, may result in pulmonary obstructive arteriopathy, which leads to increased PVR that will result in shunt reversal. Eisenmenger syndrome is defined as CHD with an initial large systemic-to-pulmonary shunt that induces progressive pulmonary vascular disease and PAH, with resultant reversal of the shunt and central cyanosis (45,46). Eisenmenger syndrome represents the most advanced form of PAH associated with CHD. The histopathologic and pathobiologic changes seen in patients with PAH associated with congenital systemic-to- pulmonary shunts (e.g., endothelial dysfunction of the pulmonary vasculature) are similar to those observed in idiopathic or other associated forms of PAH.
It has been reported that a large proportion of patients with CHD develop some degree of PAH (47–49). The prevalence of PAH associated with congenital systemic-to- pulmonary shunts in Europe and North America has been estimated to range between 1.6 and 12.5 cases per million adults, with 25% to 50% of this population affected by Eisenmenger syndrome (50). Following the Dana Point meeting, it was decided to update the pathologic and pathophysiologic classification of CHD with systemic-to-pulmonary shunts (Table 4) to provide a more detailed description of each condition. This anatomic and patho- physiologic classification may be too complex to be used in clinical practice; however, 4 quite distinct phenotypes can be recognized

Anatomic-Pathophysiologic Classification of Congenital Systemic-to-Pulmonary Shunts Associated With Pulmonary Hypertension (Clinical Classification of
Pulmonary Hypertension (Dana Point, 2008)

  1. Type
    1.1. Simple pre-tricuspid shunts
    1.1.1. Atrial septal defect (ASD) Ostium secundum Sinus venosus Ostium primum
    1.1.2. Total or partial unobstructed anomalous pulmonary venous return

1.2. Simple post-tricuspid shunts
1.2.1. Ventricular septal defect (VSD)
1.2.2. Patent ductus arteriosus
1.3. Combined shunts (describe combination and define predominant defect)

1.4. Complex congenital heart disease
1.4.1. Complete atrioventricular septal defect
1.4.2. Truncus arteriosus
1.4.3. Single ventricle physiology with unobstructed pulmonary blood flow
1.4.4. Transposition of the great arteries with VSD (without pulmonary stenosis)
and/or patent ductus arteriosus
1.4.5. Other

  1. Dimension (specify for each defect if >1 congenital heart defect)
    2.1. Hemodynamic (specify Qp/Qs)*
    2.1.1. Restrictive (pressure gradient across the defect)
    2.1.2. Nonrestrictive
    2.2. Anatomic
    2.2.1. Small to moderate (ASD less than or equal to 2.0 cm and VSD less than or equal to 1.0 cm)
    2.2.2. Large (ASD >2.0 cm and VSD >1.0 cm)

  2. Direction of shunt
    3.1 Predominantly systemic-to-pulmonary
    3.2 Predominantly pulmonary-to-systemic
    3.3 Bidirectional

  3. Associated cardiac and extracardiac abnormalities
  4. Repair status
    5.1. Unoperated
    5.2. Palliated (specify type of operation[s], age at surgery)
    5.3. Repaired (specify type of operation[s], age at surgery)

Clinical Classification of Congenital Systemic-Pulmonary Shunts Associated with Pulmonary Hypertension

  • Eisenmenger syndrome: includes all systemic-to-pulmonary shunts resulting from large defects and leading to a severe increase in PVR and a reversed (pulmonary-to-systemic) or bidirectional shunt; cyanosis, erythrocytosis, and multiple organ involvement are present
  • PAH associated with systemic-to-pulmonary: includes moderate to large defects; PVR is mildly to moderately increased, systemic-to-pulmonary shunt is still prevalent, shunts and no cyanosis is present at rest
  • PAH with small defects: small defects (usually ventricular septal defects