A 5-year-old Djiboutian boy was admitted to our hospital with shortness of breath after exertion. After every few steps, he had to stop and squat ( Fig. 1 A ). Physical examination revealed cyanosis, digital clubbing and a systolic murmur at the left third intercostal space. Blood oxygen saturation was 60%. Electrocardiography showed sinus tachycardia (120/minute) with right ventricular hypertrophy. Transthoracic echocardiography revealed a large infundibular ventricular septal defect (VSD), right ventricular hypertrophy and an over-riding aorta originating above the VSD ( Fig. 1 B). Severe right ventricular outflow tract (RVOT) stenosis was associated ( Fig. 1 C). The origin of the coronary arteries was normal. The patient was diagnosed as having tetralogy of Fallot. Outcome was favourable after total corrective surgery: VSD closure and RVOT widening were performed. “Squatting” is a historical clinical sign, exceptional and unexpected in industrialized countries but not in developing countries. Children with tetralogy of Fallot and severe RVOT obstruction discover early in life the symptomatic relief obtained by squatting (knee-chest posture) after exercise, as shown in this case. Firstly, squatting helps to maintain peripheral vascular resistance by diminishing blood flow to the legs; it transiently increases the pressure in the aorta and left ventricle, causing less blood to move into the left ventricle and more blood to move out of the pulmonary artery to the lungs. Secondly, squatting allows the oxygen debt after exercise to be paid off over a longer period and corrects the precipitous fall in arterial oxygen saturation due to exercise. After corrective surgery, children recover normal posture.
