Growth and development of the pulmonary vascular bed in patients with tetralogy of Fallot with or without pulmonary atresia.

Abstract

SUMMARY In a consecutive autopsy series of 17 patients with tetralogy of Fallot (TOF), including five patients with associated pulmonary atresia (TOF + PA), radiopaque material was injected into the pulmonary and collateral arteries and the lungs were examined using quantitative techniques to assess pulmonary vascular and alveolar structure and growth.Three types of systemic collateral arteries (SCA) were distinguished by their origin, each showing a characteristic type of "anastomosis" with a pulmonary artery: Bronchial artery collaterals arise from bronchial arteries (so judged by origin and distribution) and anastomose with pulmonary arteries inside the lung. Direct aortic collaterals arise from the descending aorta, enter the lung at the hilum and supply a lobe, or at least a segment. Inside the lung, structure and distribution are those of a pulmonary artery; outside the lung, those of a systemic artery. These vessels sometimes anastomose inside the lung with pulmonary arteries from neighboring segments of lobes. Indirect aortic collaterals arise from major branches of the aorta other than bronchial arteries (e.g. internal mammary, subclavian), and usually anastomose with the central pulmonary arteries outside the lung.All three types of SCAs were found in TOF + PA, but only bronchial artery collaterals were found in TOF. SCAs narrowed at the site of anastomosis with a pulmonary artery; this apparently protected the peripheral intraacinar arteries from high flow and pressure and prevented changes of excessive muscularity and intimal hyperplasia.In most patients, the intraacinar arteries were smaller than normal; in patients who had large, surgically created shunts of long duration they were fewer in number, of greater muscularity and with severe occlusive changes of intimal hyperplasia. The number of alveoli was reduced in almost all patients, but because alveolar size was increased, only a few patients had a small lung volume.Early surgical correction of TOF may prevent the impairment in alveolar and vascular growth described here. In TOF + PA patients, selective arteriography of all large aortic collaterals should be performed preoperatively to determine their intrapulmonary distribution and relationship with central pulmonary arteries. This will help in selecting the surgical procedure and identify collaterals that can be safely ligated.RECENT ADVANCES in cardiac surgery allow correction of tetralogy of Fallot (TOF) in infancy,1-3 which may be desirable for normal structural development of the lung.4"-" However, no study has been carried out to quantify the extent of impaired lung and vascular growth from infancy to adulthood in paFrom the

Differential regurgitation in branch pulmonary arteries after repair of tetralogy of fallot: a phase-contrast cine magnetic resonance study

“…Furthermore, it has been reported that the intra-acinar arteries in TOF are smaller than normal, and the number of alveoli are reduced. 23,24 These findings are considered secondary to decreased pulmonary blood flow before repair, which is often more marked in the left lung. 11,12,25 Although speculative, any or all of these mechanisms may conspire to influence the degree of pulmonary regurgitation from an individual lung, and all warrant further investigation.…”

“…22,23 Also not assessed was whether differential regurgitation was a universal phenomenon present in most cases with pulmonary regurgitation of other origins. It would be important to understand the mechanics of regurgitant flow by using 3D computer modeling, which could provide insights into future modifications or new developments of surgical and interventional procedures.…”

Definition and Management of Segmental Pulmonary Hypertension

“…The pathophysiology of segmental PH has not been well studied, but is likely to be the result of increased shear stress from excessive flow and pressure by large collaterals or abnormal origin of the PAs (similar to what is observed in patients with a large ventricular septal defect, patent ductus arteriosus, and common arterial trunk) 28. Moreover, hypoplasia of the pulmonary vascular bed is described in children.…”

Unilateral Diaphragmatic Paralysis Inhibits Postnatal Lung Growth in the Piglet

“…Second, P,, in the midthorax and biochemical analysis of the whole lung must tend to conceal the most distinct regional effects of unilateral diaphragmatic paralysis, which are likely to be in the lower lobe close to the paralyzed hemidiaphragm (12). Third, increase in alveolar oxygen tension (13) or decrease in pulmonary blood flow (14) may inhibit postnatal lung growth. It is unlikely that unilateral diaphragmatic paralysis increased alveolar oxygen tension or decreased pulmonary blood flow bilaterally to explain the bilateral inhibition of parenchymal growth.…”