Tetralogy of Fallot
The combination of a harsh grade 4 systolic ejection murmur and a boot-shaped cardiac silhouette on chest x-ray is pathognomonic for Tetralogy of Fallot (ToF). 1
Clinical Presentation
This classic radiographic finding represents the characteristic cardiac anatomy of ToF, which consists of four key components 2:
- Subpulmonary infundibular stenosis (causing the harsh systolic ejection murmur)
- Ventricular septal defect (VSD)
- Overriding aorta (less than 50% override)
- Right ventricular hypertrophy (contributing to the boot-shaped appearance)
The Boot-Shaped Heart
The distinctive "boot-shaped" or "coeur en sabot" appearance on chest x-ray results from 1:
- Upturned cardiac apex from right ventricular hypertrophy
- Concave pulmonary artery segment due to pulmonary artery hypoplasia and stenosis
- Right aortic arch (present in approximately 25% of cases) 2
The Systolic Ejection Murmur
The harsh grade 4 systolic ejection murmur originates from 2:
- Right ventricular outflow tract (RVOT) obstruction at multiple potential levels
- Infundibular (subpulmonary) stenosis
- Pulmonary valve stenosis (valve is often small and stenotic)
- Pulmonary artery hypoplasia or stenosis
Presentation Context
Unoperated Adult Patients
While rare in developed countries, unoperated ToF can present in adulthood in 2:
- Immigrants without prior access to cardiac surgery
- "Pink tetralogy" patients with relatively mild pulmonary obstruction and minimal cyanosis
- These cases are often initially misdiagnosed as simple VSD due to the loud precordial murmur
Key Diagnostic Pitfall
The loud murmur can mislead clinicians into diagnosing a simple VSD rather than recognizing the complete ToF anatomy. Always obtain a chest x-ray when evaluating a loud systolic murmur—the boot-shaped heart immediately distinguishes ToF from isolated VSD. 2
Additional Clinical Findings to Expect
Beyond the murmur and x-ray findings, look for:
- Cyanosis and clubbing (in patients with severe RVOT obstruction)
- Continuous murmurs over the thorax (if abundant aorticopulmonary collaterals are present)
- Right ventricular heave from RV hypertrophy
- Single or loud S2 (P2 component may be diminished or absent)
Immediate Next Steps
Transthoracic echocardiography is mandatory to confirm the diagnosis and define 2:
- VSD size and location (typically large and subaortic)
- Degree and level(s) of RVOT obstruction
- Pulmonary artery anatomy and size
- Aortic override percentage
- Associated lesions (ASD, coronary anomalies)
Cardiac catheterization may be needed to fully delineate coronary artery anatomy before any surgical intervention, as anomalous coronary arteries (particularly left anterior descending) are common and critical to identify pre-operatively 2.