Surgical Repair Of Congenital Defects Research Articles

The transitional circulation: Physiology and anesthetic implications

Over the past decade, several aspects of the physiology of the transitional circulation have been elucidated. The transitional circulation may be viewed as a process divided into four phases. The concept of these phases underscores the fact that the normal transitional circulation should be viewed as an orderly process and not a single event. Within these phases, several mechanisms seem to be involved in the control of pulmonary vascular resistance (PVR). Yet even these mechanisms do not completely explain the process of the normal transition, and very little is understood about why the transition occasionally fails. No doubt other as yet undescribed mechanisms also play a role. Much work remains to be done in the study of the normal and abnormal transitional circulation. The profound hypoxia that characterizes infants with failed transitional circulation from any cause is due to a persistently high PVR, causing right-to-left shunting at the ductal and foramental levels. Clinical care of these infants is based on efforts to simultaneously decrease PVR and increase systemic vascular resistance (SVR). Appropriate measures include the use o f supplemental oxygen, hyperventilation, alkalinization, and sedation to decrease PVR and intravenous (IV) fluids and pressors to increase SVR. The rapidly fluctuating nature of the physiologic processes that cause failure of the transitional circulation must be kept in mind when caring for these infants, both during initial stabilization in the delivery room and while administering anesthesia for surgical repair of congenital defects.

Open-heart Surgery for Repair of Congenital Defects

Anyone anxious to know more about developments in the rapidly-expanding field of surgical repair of congenital defects of the heart by open-heart techniques will find this paper instructive. The various types of apparatus which have been used to maintain the circulation and oxygenation of blood outside the body, leaving the heart free for surgical repair, are described. The physiologic changes during total-body perfusion and the means taken to insure homeostasis during the procedure are discussed. The author gives a brief description of his experience in the repair of congenital defects of the heart with the various techniques. A considerable body of interesting information is provided in a succinct and clear fashion for the general reader.

In Vitro Oxygenation of Fresh Whole Blood for Arterial Perfusion

With the elucidation of the "azygos flow factor" by Andreason and Watson,¹it was established that a markedly reduced venous return and cardiac output were compatible with prolonged survival in dogs. Lillehei²has demonstrated that with caval occlusion produced at normal body temperature azygos vein flow into the right atrium is compatible with survival for periods of 30 to 60 minutes. In dogs this flow amounted to 8 to 14 ml. per kilogram of body weight per minute and was less than 10% of the basal cardiac output. The clinical application of this principle resulted in "cross circulation procedures." with blood flow between donor and patient regulated in the range of 20 to 25 ml. per kilogram per minute. This technique permitted open right cardiotomy and the surgical repair of congenital defects of the interatrial and interventricular septa. Recently, in many laboratories, pump oxygenators have been developed to