CHD in Down Syndrome Cheatsheet
Key Concept: Fixed split S2 = ASD hallmark (right heart delay doesn't change with breathing). Down syndrome → AVSD in 40% (endocardial cushion defect = ASD + VSD + common AV valve). PS = widely split S2 that DOES vary with breathing. PDA = continuous machinery murmur + bounding pulses.
| Diagnosis |
Key Features |
| ASD / AVSD |
- Fixed split S2 (does NOT vary with respiration) = ASD hallmark
- Systolic ejection murmur at left upper sternal border (relative pulmonic stenosis)
- AVSD (endocardial cushion defect) most common CHD in Down syndrome
- RV volume overload → right heart enlargement
- Presents in infancy with failure to thrive
- Primum ASD (AVSD) → left axis deviation on ECG
- Large shunt → Eisenmenger syndrome risk if unrepaired
- Treated surgically
|
| VSD |
- Holosystolic murmur at left lower sternal border
- Thrill if large
- Split S2 is NOT fixed (varies with respiration)
- Pulmonary overcirculation → bibasilar rales
- Present in Down syndrome but less common than AVSD
- Small VSDs may close spontaneously
- Large VSDs need surgical repair or catheter-based closure
|
| PDA |
- Continuous "machinery" murmur (systolic + diastolic)
- Bounding peripheral pulses; widened pulse pressure
- More common in premature infants
- Indomethacin (premature) or surgical ligation
- Not specifically associated with Down syndrome more than baseline
|
| Pulmonic Stenosis |
- Systolic ejection murmur at left upper sternal border
- Ejection click
- Widely split S2 (NOT fixed — varies with respiration)
- Right ventricular hypertrophy
- Associated with Noonan syndrome more than Down syndrome
- Mild PS often doesn't need treatment
- Moderate-severe → balloon valvuloplasty
|
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