Congenital Heart Disease: Pathological Essentials
Congenital heart disease is the most common type of birth defect. Classification revolves around the presence of shunts (left-to-right vs. right-to-left) and cyanosis.
1. Left-to-Right Shunts (Late Cyanosis)
Characterized by increased pulmonary blood flow. Over time, pulmonary hypertension can lead to the Eisenmenger syndrome (shunt reversal, leading to late cyanosis).
| Defect | Pathological Note |
|---|---|
| VSD | Most common congenital cardiac defect. Often associated with Fetal Alcohol Syndrome. |
| ASD | Ostium secundum is the most common type. Fixed, split S2 is the hallmark physical exam finding. |
| PDA | Associated with congenital rubella and prematurity. “Machine-like” continuous murmur. Treat with indomethacin (closes PDA). |
2. Right-to-Left Shunts (Early Cyanosis)
- Tetralogy of Fallot (ToF): The most common cause of early cyanosis. Four features: VSD, Overriding aorta, Pulmonary stenosis, and Right ventricular hypertrophy. Presents with “Tet spells” (cyanosis relieved by squatting).
- Transposition of the Great Vessels: Aorta arises from RV, pulmonary artery from LV. Incompatible with life unless a shunt (VSD, ASD, or PDA) exists. Associated with maternal diabetes.
3. Exam Must-Knows
Pathology Pearl: Coarctation of the aorta (pre-ductal type) is associated with Turner syndrome and presents with rib notching on X-ray and brachial-femoral pulse delay.
- Truncus Arteriosus: Failure of the truncus to divide; requires a VSD for survival.
- Tricuspid Atresia: Complete absence of the tricuspid valve; requires an ASD and VSD for survival.