Health-care utilization and respiratory morbidities in preterm infants with pulmonary hypertension.

OBJECTIVE: To assess health-care utilization and risk of respiratory morbidities in preterm infants with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH). STUDY DESIGN: Retrospective data were obtained from subjects (n=109) attending a BPD clinic. Subjects were stratified by the presence or absence of PH before and after 2 months of age. Analytic methods included t-tests, χ(2) tests and regression. RESULT: Subjects with BPD and PH present after 2 months of age were hospitalized for 2.2 months longer than those without PH (P=0.02). These subjects were 4.5 times more likely to receive home supplemental oxygen or mechanical ventilation (P=0.03). No difference in the risk of respiratory morbidities after initial hospital discharge was seen with PH. CONCLUSION: PH in preterm infants is associated with longer initial hospitalizations and a higher likelihood of requiring home respiratory support. This has implications for counseling families and reducing the medical, psychosocial, and economic burden of BPD and PH.

Concentric placement of stents to relieve an obstructed anomalous pulmonary venous connection.

A 9-month-old male with asplenia and complex congenital heart disease experienced progressive stenosis of an anomalous pulmonary venous connection. He developed pulmonary edema and growth failure. Two stents were placed concentrically to relieve the stenosis, and the pulmonary edema and growth failure resolved. Definitive surgery was accomplished 8 months later.

Right subscapular artery catheterization for balloon valvuloplasty of critical aortic stenosis in infants.

This study was performed to evaluate the utility and safety of catheterizing the right subscapular artery for balloon valvuloplasty of critical aortic stenosis in infants. Twenty-one patients, age 20 days to 17 months, underwent attempted valvuloplasty through the surgically exposed right subscapular artery. Five or 7Fr catheters with balloon diameters of 7 to 10 mm were used. Valvuloplasty was successfully performed using this approach in 11 patients. In 2 other patients, the subscapular artery would not accommodate the balloon angioplasty catheter (7Fr), and the arteriotomy was extended into the axillary artery. In these 13 patients, the peak systolic pressure gradient across the aortic valve was decreased from 85 +/- 23 to 33 +/- 7 mm Hg. Moderate aortic regurgitation developed in 3 patients. In the remaining 8 patients, valvuloplasty could not be performed through the right subscapular artery. In 2 patients, the right subclavian artery was anomalous and led to the descending aorta. In 6 small patients, no catheter could be advanced across the aortic valve. In 1 of these patients, a guidewire perforated a coronary sinus of Valsalva causing death. Overall, valvuloplasty using the right subscapular arterial approach was successful in 13 of 19 infants (68%) with normal right subclavian arteries, including all 10 such patients weighing > or = 5.5 kg. No clinically significant peripheral vascular complications or brachial plexus injuries occurred. Thus, the right subscapular arterial approach is an alternative route to be considered when planning balloon aortic valvuloplasty in infants.

Pulmonary venous atrial obstruction after the Senning procedure: relief by catheter balloon dilatation.

Pulmonary venous atrial stenosis developed after a modified Senning procedure in an infant with transposition of the great arteries. The pulmonary venous atrium was surgically revised, but the obstruction recurred. The stenosis was then enlarged by percutaneous balloon catheter dilatation. There was an immediate haemodynamic and echocardiographic improvement. Clinical and echocardiographic improvement persisted nine months after dilatation. The procedure was complicated by staphylococcal endarteritis.

Neonatal mitral valve endocarditis: diagnosis and successful management.

Although still considered to be a rare and mostly fatal illness, the reported incidence of neonatal bacterial endocarditis has increased during the past decade. This parallels the establishment of intensive supportive management of severely ill newborns with multiple medical problems. An extremely difficult diagnostic problem with protean manifestations, the presence of neonatal endocarditis should be vigorously sought in the at risk neonate. The authors report the first known case in America of successfully diagnosed and treated neonatal endocarditis involving the mitral valve.

Hypoxia inhibits proliferation of fetal pulmonary arterial smooth muscle cells in vitro.

Normal pulmonary arterial development in the relatively hypoxic intrauterine environment and pulmonary arterial remodeling in hypoxic infants include extension of the smooth muscle layer into normally nonmuscular arteries and thickening of the arterial media in the muscular arteries. These changes require proliferation of immature smooth muscle cells or differentiation of smooth muscle cell precursors. Because the mechanisms that regulate these processes have not been clearly defined, we asked whether decreased oxygen tensions could promote either hyperplasia or hypertrophy of smooth muscle cell precursors in vitro. We have studied cells that proliferate and migrate out of explants from the media of the pulmonary arteries of near-term bovine fetuses, because these cells are representative of those that are involved in normal arterial development and possibly also in arterial remodeling. Decreases in oxygen tension within and below the physiologic range do not cause hyperplasia or hypertrophy of these cells. Instead, cell proliferation decreased at oxygen tensions below 60 mm Hg. The effects of hypoxia on proliferation of aortic and pulmonary arterial smooth muscle cells were identical, but effects on proliferation of dermal fibroblasts and endothelial cells were smaller in magnitude and evident only at lower oxygen tensions. These findings suggest that hypoxia does not act directly on smooth muscle cells to produce increased quantities of these cells in the pulmonary arteries during normal prenatal development or during remodeling of the pulmonary arteries of the hypoxic neonate, implying that other factors mediate these phenomena.

Heparin inhibits proliferation of fetal vascular smooth muscle cells in the absence of platelet-derived growth factor.

Proliferation of smooth muscle cells from the pulmonary arteries and aortas of fetal calves is inhibited by heparin in vitro. This effect is reversible and dose dependent. Comparisons with effects of other polysaccharides indicate that only extensively sulfated polysaccharides inhibit proliferation of smooth muscle cells but that specific structural features of heparin are required to achieve maximum effect. Heparin-Sepharose chromatography of medium containing fetal calf serum reduces the ability of that medium to promote growth of smooth muscle cells from fetal pulmonary arteries, suggesting that heparin may remove soluble growth factors in serum. However, inhibition of fetal pulmonary artery smooth muscle cell proliferation by heparin is identical in media supplemented either with serum prepared from fetal calf plasma, in which platelet-derived growth factor (PDGF) is not detectable, or with fetal calf serum, which contains relatively abundant PDGF (114 pg/ml). Thus, inhibition of fetal pulmonary artery smooth muscle cell proliferation by heparin is not mediated solely by decreased availability or activity of exogenous PDGF. These studies suggest that morphogenesis of the smooth muscle investment of the pulmonary arteries could be regulated by local production of heparin-like inhibitors of smooth muscle cell growth.

Severe superior vena cava syndrome and hydrocephalus after the Mustard procedure: findings and a new surgical approach.

Some degree of obstruction of the superior vena cava is common after the Mustard operation for transposition of the great arteries. This can cause superior vena cava syndrome, which in extreme cases may lead to hydrocephalus in young children. While revision of the intra-atrial baffle can be performed, this procedure is associated with significant morbidity and mortality and may not resolve the problem. We describe an alternative operative approach in a group of patients who had superior vena cava syndrome after the Mustard procedure: anastomosis of the innominate vein to the left atrial appendage. This procedure is not complicated to perform and is safe; symptoms were relieved in all patients.