The electron microscopic alterations of the alveolar septum in advanced hemodynamin and alloxan-induced pulmonary edema were compared. Pulmonary edema was produced in anesthetized dogs by means of increased lefy atrial pressure and hemodilution and by allocan administration. Sections of pulmonary tissue from these dogs and similarly anesthetized controls were processed for and examined by light and electron microscopy. In the hemodynamic form of edema the interstitial fluid collects only in the collagen-containing portions of the septum. The endothelium, epithelium, their respective basement membranes and large portions of the air-blood barrier are unaffected. Alloxaninduced edema, in contrast, is characterized by degeneration of both endothelium and epithelium and by the appearance of fibrin within the alveoli. The hemodynamic type of pulmonary edema appears to result from an accentuation of the normal process of fluid exchange within the lung. Allocan-induced edema, on the other hand, is a pathologic process. The functional implications of these results are discussed.

Four infants with Down syndrome developed cor pulmonale and heart failure in association with chronic upper airway obstruction. Features of the sleep apnea syndrome were conspicuous; namely, noisy breathing with retraction, cyanosis and frequent apnea during sleep, and daytime lethargy and somnolence. The clinical picture masqueraded as cyanotic congenital heart disease. Arterial blood gas analyses revealed alveolar hypoventilation, especially during sleep. The nature of the obstructive element was variable. Adenoidectomy provided partial relief in one patient, and tonsillectomy and adenoidectomy resulted in temporary improvement in two others. Three patients were markedly benefitted by tracheostomy. Functional inspiratory pharyngeal closure was demonstrated fluorographically in one patient. Infants with Down syndrome may be predisposed to upper airway obstruction by virtue of hypoplasia of facial and oropharyngeal structures and generalized hypotonia. Additional obstructive elements may be contributed by hypertrophied lymphoid tissue, excessive secretions, and glossoptosis. Removal of the obstructive element is helpful, but functional obstruction may only be relieved by tracheostomy.

Summary. The forces governing the movement of water across the pulmonary capillaries were studied in 39 intact, spontaneously breathing dogs. A situation favoring the net movement of water out of the pulmonary capillaries was created by means of partial pulmonary venous obstruction (left atrial balloon catheter) followed by rapid saline hemodilution. A predetermined difference between pulmonary capillary and plasma colloid osmotic pressures was maintained for periods of 1 to 2 hours. Left atrial (PLA) and plasma colloid osmotic pressures (7rp1) were measured directly. The water content of the lungs was measured serially by an indicator-dilution technique, and at autopsy by drying the lungs. The rate of accumulation of lung water was measured in four groups of animals: in three of the groups, the capillary hydrostatic and colloid osmotic pressures were varied; in the fourth group, the right lymphatic duct was obstructed in addition.The average rate of water accumulation in the lungs varied in a nonlinear way with the level of the capillary hydrostatic-plasma colloid osmotic pressure difference and was unaffected by the level of the capillary hydrostatic pressure. At low levels of PLA -7rpl, water accumulated in the lung at an average rate of 0.09 g per g dry lung per hour per mm Hg pressure difference.At higher levels of PLA -7rpl the average rate of accumulation was 0.22 g per g per hour per mm Hg AP; in most of the experiments in this group water accumulated in the lungs slowly during the first 30 minutes of the test period and more rapidly as the period was extended. Obstruction of right lymphatic duct outflow did not alter the rate of water accumulation. Based on the control data of the present experiments, the pericapillary pressure in normal lungs is estimated to be of the order of -9 mm Hg in the normal dog lung. The filtration coefficient for the pulmonary capillaries is estimated to be of the order of one-tenth to one-twentieth of that for canine muscle capillaries. The data of the present study indicate that edema formation in lung tissue cannot be defined solely in terms of intravascular forces, but may be governed to a significant degree by changes in pericapillary forces in the pulmonary interstitium.

FIGURE 1X-ray of the chest showing the positions of the different catheters in the aorta (Ao), the right atrium (RA), the left atrium (LA), the pulmonary artery (PA), the inferior vena cava (1VC), and the esophagus (Es). TIME OF INFUSION m i n FIGURE 2Hemodynamic events during the experimental production of pulmonary engorgement and edema (dog no. 41). Inflation of the balloon in the left atrium, followed promptly by the rapid infusion of saline, produced abrupt increase in left atrial and pulmonary arterial mean pressures (top panel); at the same time, there was a decrease of colloid osmotic pressure, hematocrit, and total proteins. High pressure in the left atrium was maintained for one hour by adjusting rate of infusion.

No abstract

Contrast enhanced cardiac computed tomography angiography (CTA) is a prominent imaging modality for diagnosing cardiovascular diseases non-invasively. It assists the evaluation of the coronary artery patency and provides a comprehensive assessment of structural features of the heart and great vessels. However, physicians are often required to evaluate different cardiac structures and measure their size manually. Such task is very time-consuming and tedious due to the large number of image slices in 3D data. We present a fully automatic method based on a combined multi-atlas and corrective segmentation approach to label the heart and its associated cardiovascular structures. This method also automatically separates other surrounding intrathoracic structures from CTA images. Quantitative assessment of the proposed method is performed on 36 studies with a reference standard obtained from expert manual segmentation of various cardiac structures. Qualitative evaluation is also performed by expert readers to score 120 studies of the automatic segmentation. The quantitative results showed an overall Dice of 0.93, Hausdorff distance of 7.94 mm, and mean surface distance of 1.03 mm between automatically and manually segmented cardiac structures. The visual assessment also attained an excellent score for the automatic segmentation. The average processing time was 2.79 minutes. Our results indicate the proposed automatic framework significantly improves accuracy and computational speed in conventional multi-atlas based approach, and it provides comprehensive and reliable multi-structural segmentation of CTA images that is valuable for clinical application. INDEX TERMS Computed tomography, heart segmentation, multi-atlas segmentation, random walk.

ANOMALOUS ORIGIN of the right pulmonary artery from the ascending aorta is a rare malformation that may cause death in infancy or early childhood. It is probably derived from embryologic failure of migration of the right sixth aortic arch to join its counterpart on the left before the truncus is divided into the aorta and pulmonary artery. ' The purpose of this communication is to report the clinical and necropsy findings of three cases of congenital absence of the right pulmonary artery in which the right lung received its entire blood supply from a single large vessel arising from the ascending aorta. In these cases, there were no associated cardiovascular defects.This malformation presents a unique hemodynamic situation in which one lung is perfused by the systemic circulation and the other by the pulmonary circulation. Early diagnosis is important, since the lesion is amenable to surgical correction.Review of the Literature The anomaly illustrated by our three cases is characterized by (1) absent right branch of the pulmonary artery, (2) a single large vessel that arises from the ascending aorta and enters the hilus of the right lung, constituting its sole arterial supply, and (3) normal size and structure of the right lung. Thus defined, aortic origin of the right pulmonary artery is very rare as an isolated malformation. Our case 1 was previously reported by Maier.2The association of this lesion with other vascular malformations, e.g., aorticopulmo-

Previously unreported lung disease found at autopsy in 2 young infants with Down's syndrome and congenital heart disease (complete atrioventricular canal malformation with left-to-right shunt) is described. The perinatal and neonatal period was unremarkable, and there was no history of mechanical ventilation or administration of high concentration of oxygen for extended periods. In 1 of the cases respiratory symptoms and hyperinflation with focal cystic changes in the lung fields on chest X-ray were noted at 5-7 months of age. Pathologically there was cystic dilatation of alveoli with focal cuboidal metaplasia of alveolar epithelium and mild to moderate focal alveolar septal fibrosis. Wilson-Mikity syndrome, congenital pulmonary lymphagiectasia, bronchopulmonary dysplasia, and idiopathic interstitial fibrosis of lungs were ruled out on clinical and/or pathologic grounds. Factors such as compression of bronchi by enlarged pulmonary arteries or cardiac chambers, peribronchiolar accumulation of fluid, pulmonary hypoplasia occurring in Down's syndrome, and episodes of pulmonary arterial hypoperfusion associated with severe congenital heart disease may be related to the pathogenesis of the lesion.