S’s mother brought him to the clinic after noticing that he becomes unusually breathless and fatigued during play. She also observed that his lips and fingertips turn grey, especially when he is crying or feeding. S has had several episodes of fainting and squats down instinctively when he gets tired or breathless. His growth has been poor, and he is smaller than other children his age. S was born at home, with no complications reported during birth, but access to healthcare has been limited due to the rural setting.

Since birth, S has had frequent respiratory infections, and a doctor in their local clinic noticed a heart murmur during a previous clinic visit when he was 6 months old. The family has limited access to clean water and healthcare, and S has not received regular follow-up care. No family history of heart disease was reported.

Vital signs: Heart rate: 110 bpm, respiratory rate: 30 breaths/min, oxygen saturation: 85% on room air, blood pressure: normal for age.

General appearance: Small for age, with signs of cyanosis (greyish discoloration of the lips, nail beds, and tongue)

Cardiovascular: Harsh systolic ejection murmur at the left upper sternal border, visible right ventricular heave

Respiratory: Clear lung fields

Extremities: Mild clubbing of the fingers, cyanosis

Growth parameters: Weight and height below the 3rd percentile for age

Laboratory and Imaging Results:

Chest X-ray: Boot-shaped heart (right ventricular hypertrophy), normal lung fields

Echocardiogram: Confirms Tetralogy of Fallot (TOF) with the following defects:

Ventricular septal defect (VSD)

Pulmonary stenosis 

Overriding aorta

Right ventricular hypertrophy

S is diagnosed with Tetralogy of Fallot (TOF), a congenital heart defect causing cyanosis, breathlessness, and poor growth due to reduced oxygenation of the blood. His "tet spells" (episodes of cyanosis and fainting) are typical for children with this condition.

1. Oxygen therapy: Administer supplemental oxygen during cyanotic episodes.
2. Beta-blockers (Propranolol): To help reduce the frequency of tet spells.
3. Nutritional support: High-calorie diet to support growth and development.
4. Surgical referral: S will need referral to a tertiary care center for corrective surgery (complete surgical repair of TOF), which is the definitive treatment.
5. Parental education: Educate S’s mother on recognizing and managing cyanotic spells and the importance of squatting during episodes of breathlessness to increase oxygen flow.

S’s prognosis depends on his access to timely surgical intervention, as untreated TOF can lead to significant complications. With surgery, his chances of leading a relatively normal life will improve significantly.