Pulmonary Sequestration: A Case of an Intermediate Link between Extra- and Intralobar Sequestration and its Haemodynamics

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Abstract
A patient operated upon for an extralobar pulmonary sequestrum connected by a narrow lung tissue pedicle to the left lower lobe is described. This case represents a definite intermediate link between intra- and extralobar sequestration, thus lending heavy support to the theory that these disorders are intimately related in aetiology and pathogenesis. Haemodynamic measurements demonstrated a systemic pressure and a blood flow of 739 ml/min through the aberrant artery to the sequestrum. This significant flow through non-functioning tissue is stolen from the cardiac output. Pulmonary sequestration occurs in both extralobar and intralobar forms. Extralobar sequestration is rare and consists of an accessory ectopic lobe lying outside the normal lung, enclosed in its own visceral pleura. The commoner intralobar form lies within the visceral pleura of an otherwise normally developed pulmonary lobe. The sequestrum usually has no communication with either the pulmonary artery or the bronchial tree, and its blood supply originates from the aorta. Both extra- and intralobar sequestration are congenital disorders (James & Cuthbert, 1967). Their pathogenesis and the relationship between them remain a matter of controversy (Blesovsky, 1967). Haemodynamic measurements in pulmonary sequestration have not been reported. Observations in a patient of ours may help to elucidate these aspects of pulmonary sequestration.