Surgical correction of tetralogy of Fallot with previous systemic to pulmonary artery shunts

Fifty-four patients with previous Blalock (32) and Potts (22) systemic artery-pulmonary artery shunts and subsequent total correction for tetralogy of Fallot are reported. A separate posterolateral approach was employed to obliterate the Potts shunt. There were seven operative deaths and two late deaths. Infundibular stenosis with a normal pulmonary valve gave the best results. In comparison with our concomitant series without a shunt, the presence of a Blalock or Potts anastomosis did not affect the over-all result. Postoperative bleeding was a major complication, requiring reoperation in seven. An excellent result with probable cure was obtained in 30, and there was good improvement in ten of the 54 patients.

Effects of carbon dioxide and oxygen on properties of experimental seizures in mice

The influence of various concentrations of carbon dioxide and oxygen on the pattern of maximal electroshock seizures (MES), on pentylenetetrazol (Metrazol)-induced seizures, and on recovery time (RT50) from MES has been studied in mice. The major results are summarized as follows: Increasing the concentration of carbon dioxide in 20% oxygen resulted in marked changes in the MES pattern. The duration of the tonic flexor component was increased, and the duration of the tonic extensor component and of the entire tonic phase was decreased; the ratio of flexion to extension was increased markedly. These changes indicate an anticonvulsant effect of carbon dioxide. Carbon dioxide in a concentration of 15.6% protected 50% of mice against a 97% convulsant dose (CD97) of Metrazol. Hypoxia, induced by inhalation of 15 or 10% oxygen, decreased the duration of the tonic flexor component and increased the duration of the tonic extensor component of the MES; the duration of the entire tonic phase was increased; the ratio of flexion to extension was slightly decreased. These changes indicate an excitatory effect of low oxygen concentrations on the brain, under the stated conditions. Hyperoxia, induced by inhalation of 50, 75 or 90% oxygen, in contrast to hypoxia, resulted in effects on MES similar to those produced by inhalation of carbon dioxide. The RT50 was slightly, but not significantly, decreased by hypoxia (15% oxygen), unchanged by hyperoxia (50% oxygen), and markedly increased by an increase in carbon dioxide concentration. Carbon dioxide (5 and 10%) combined with hypoxia (10% oxygen) produced effects on MES pattern and RT50 similar to those produced by carbon dioxide in 20% oxygen.