INTERNATIONAL ABSTRACTS 679

reduced following oligohydramnios (0.83 _+ 0.04 v 0.90 _+ 0.02, P < .025). The hypoplastic lungs contain fewer saccules (fetal "alveoli") (46 +_ 20 v 69 _+ 23 x 106, P < .1) and the surface area that would be available for gas exchange is decreased (698 _+ 234 v 974 +_ 80 cm 2, P < .05). Lung volume and volume proportion of parenchyma are reduced in the experimental lung, and, therefore, diminished parenchymal elastic tissue is anticipated. However, the total length of parenchymal elastic tissue in the experimental lungs is decreased to a surprising degree and is little more than half the length in control lungs (504 _+ 222 v 974 _+ 70 m, P < .0025). Such marked reduction in total length suggests that factors other than smaller lung size have contributed to the decrease of elastic tissue in the experimental group. In fact, elastic tissue length per unit volume is significantly reduced (509 _+ 189 v 809 _+ 115 m/cm 3, P < .025) indicating an absolute decrease in parenchymal elastic tissue in the hypoplastic lungs. These data show that even a brief period of oligohydramnios beginning in the canalicular phase of development significantly reduces and modifies fetal guinea pig lung growth.-- Prem Puri

HEART AND GREAT VESSELS

Prenatal Diagnosis of Congenital Heart Defects in Thoracoabdomi- nally Conjoined Twins. S.P. Sanders, A.J. Chin, I.A. Parness, et al. N Engl J Med 313:370-374, (August 8), 1985.

Options for the treatment of thoracoabdominally conjoined twins are largely dependent on the anatomy of the cardiovascular system. This report describes the experience with the prenatal determination of the extent of cardiac conjunction by fetal echocardiography and the diagnosis of associated defects by ultrasound in four pairs of thoracoabdominally conjoined twins. In addition to determining the extent to which the hearts are joined, echocardiography correctly diagnosed the major abnormalities of the common heart. The abnormalities most commonly missed by prenatal study were anom- alies of systemic or pulmonary venous connection. The prognosis for postnatal separation could be determined on the basis of the cardio- vascular anatomy--Scott Adzick

Late Results After Left-sided Cardiac Valve Replacement in Chil- dren. A. Milano, P.R. Vouhe, T. Bailott-Vernant, el al. J Thorac Cardiovasc Surg 92:218-225, (August), 1986.

Left-sided cardiac valve substitutes were implanted in 166 chil- dren from 1976 to 1984. Bioprostheses were used in 84 patients, mechanical prostheses in 71, and both mitral bioprostheses or aortic mechanical valves were implanted in 11 patients. The 7-year survival figures for all groups were similar. There were no significant differences in incidence of thromboembolic events. Reoperation rates were significantly higher in the bioprosthetic group (10.4% v 2.3%). Seven-year freedom from all valve-related complications was less in the bioprosthesis group when compared with the mechanical valve group (43 • 6% v 86 +_ 4%, P < .001). While aortic valve replacement in children is safe and has satisfactory long-term results, mitral valve replacement does not. Regardless of type of prosthesis, mitral valve replacement has higher rates of failure and complications. All efforts should be made to preserve the native mitral valve in children.--Marleta Reynolds

Congenital Diverticulum of the Ventricle. O.U.J. Okereke, D.A. Cooley, and O.H. Frazier. J Thorac Cardiovasc Surg 91:208-214, (February), 1986.

Ten patients between the ages of 4 months and 37 years presented with congenital diverticula of the ventricle. Two patients were asymptomatic and the remaining eight had symptoms ranging from palpitations to severe dyspnea. All diverticula were confirmed by

cardiac catheterization. Four patients had associated defects: fore- shortened sternum, omphalocele, large ventral hernia, and flaring of the lower anterior rib cage. There was an associated cardiac anomaly in six patients. Three of the diverticula were identified in the left ventricular outflow tract and represent the "fibrous" variety. The other six were of the muscular type and were located at the apex of the ventricle. This variety is more commonly associated with midline defects. Repair required cardiopulmonary bypass in six of nine patients. Correction of intracardiac lesions was necessary in three, and in three, the neck of the diverticulum was too large to allow simple clamping and excision. The remaining three patients under- went excision of the diverticula without bypass. Congenital ventricu- lar diverticulum should be repaired at the time of diagnosis to avoid future complications.--Marleta Reynolds

The Arterial Switch Operation. An Eight Year Experience. J.M. Quaegebeur, J. Rohmer, J. Ottenkamp, et al. J Thorac Cardiovasc Surg 92:361-384, (September), 1986.

The predicted 1-year survival after the arterial switch operation for neonates with transposition and intact ventricular septum in 1985 is 99.9% and 99.7% for those infants with transposition and a large VSD or double-outlet right ventricle. The results are clearly superior to those of the atrial switch. Fifty-five of the 66 patients who underwent arterial switch since 1977 are alive. Eight died in the postoperative period. The risk factors for death include low birth weight, transposition with a large VSD, DORV, and subpulmonary VSD, and the presence of a PDA. Early date of operation was also a risk factor. Neither coronary nor great vessel morphology were identified as risk factors. The authors review and diagram the operative technique.--Marleta Reynolds

Repair of Interrupted Aortic Arch and Associated Malformations in Infancy: Indications for Complete or Partial Repair. J. H/. Hammon, W.H. Merrill, R.L. Prager, et al. Ann Thorac Surg 42:17-21, (July), 1986.

Prohibitive hospital mortality associated with palliative proce- dures for infants with an interrupted aortic arch and associated cardiac malformations has prompted a more aggressive surgical approach. Eight patients with interrupted aortic arch and VSD or aortopulmonary window survived complete repair utilizing profound hypothermia and circulatory arrest. Four others with more compli- cated associated lesions underwent repiar of the interrupted arch and pulmonary artery banding. One survived. These two groups of patients compare favorably with another group of 11 patients with similar anatomy who had palliative surgery prior to 1980. Ten of these 11 patients died. Early complete repiar has not been without complication, and gradients have been identified in three of the long-term survivors, one requiring reoperation. The excellent results in this group of patients support the use of primary complete repair of an interrupted aortic arch with associated VSD or Ap window. The authors suggest that complete repair may be extended to include those infants with more complex lesions with an early single opera- tive procedure is contemplated for the complex lesions.--Marleta Reynolds

Incidence and Pathogenesis of Late Aneurysms After Patch Graft Aortoplasty for Coarctation. F. IV. Hehrlein, J. Mulch, H.W. Rau- tenberg, et al. J Thorac Cardiovasc Surg 92:226-230, (August), 1986.

Coarctation of the aorta was repaired with the Vosschulte tech- nique of direct and indirect aortoplasty in 317 patients. Fifty-four patients were <1 year of age at the time of operation. Follow-up ranged from 1 to 28 years. Eighteen patients developed aneurysms 4 to 18 years following repair. One of these patients died of sponta-