Pulmonary Vascular Changes in Tetralogy of Fallot

¹ Department of Pediatrics, State University of New York at Buffalo and the Edward J. Meyer Memorial Hospital

Review of the pathologic changes in the lungs, correlated with clinical findings, suggest that in the lungs of patients with tetralogy of Fallot opposing forces are at work and their effect on the outcome of corrective cardiac surgery will depend on the state of their balance at the time of operation. This dynamic situation can be summarized diagrammatically.

Slow blood flow and polycythemia lead to thrombosis. Thrombosis may be widespread, but probably seldom causes a significant reduction of the vascular capacity of the lung. Breakdown of thrombi occurs with remarkable frequency and is aided by the extensive network of systemic and intrapulmonary collateral channels. Collateral vessels also serve to increase the effective pulmonary blood flow and bypass obstructed areas.

[See figure in the PDF file]

A satisfactory shunting operation exerts a beneficial effect in causing dissolution of thrombi. In a few patients an excessive shunt has irreparably damaged the pulmonary vascular bed and has jeopardized the changes of a surgical cure.