Question
Most important prognostic marker of tetralogy of Fallot:
| A. |
VSD |
| B. |
Pulmonary stenosis |
| C. |
Overriding of aorta |
| D. |
Right ventricular hypertrophy |
Show Answer
|
Correct Answer » B Explanation |
 |
- The severity of pulmonary stenosis (right ventricular outflow tract obstruction) is the most important prognostic determinant in Tetralogy of Fallot.
- It determines:
- The degree of right-to-left shunting across the VSD.
- The severity of cyanosis.
- The frequency of hypercyanotic (Tet) spells.
- Overall survival and clinical presentation.
- Mild pulmonary stenosis results in “Pink TOF” with minimal or no cyanosis.
- Severe pulmonary stenosis causes marked right-to-left shunting, profound cyanosis, and early symptoms.
Why the Other Options Are Incorrect
A. Ventricular Septal Defect (VSD)
- The VSD in TOF is typically large and nonrestrictive in almost all patients.
- It does not determine the severity of cyanosis or prognosis.
C. Overriding aorta
- The degree of aortic override varies among patients.
- It is a characteristic anatomical feature but has little influence on prognosis compared with the severity of RVOT obstruction.
D. Right ventricular hypertrophy
- Right ventricular hypertrophy is secondary to pulmonary stenosis.
- It reflects chronic pressure overload and is not the primary prognostic factor.