Surgical improvement of hepatic venous mixing to resolve systemic arterial hypoxemia associated with post-Fontan pulmonary arteriovenous fistulae.

Pulmonary arteriovenous fistulae are known to develop in patients who have functional single-ventricle heart disease and interruption of the inferior vena cava with direct hepatic drainage to the heart, in which a bidirectional Glenn shunt is the only source of pulmonary blood flow. The progressive systemic arterial hypoxemia that is associated with pulmonary arteriovenous fistulae can have important clinical consequences. Baffling the hepatic venous return to the pulmonary circulation can alleviate pulmonary arteriovenous fistulae.Herein, we present the case of a 13-year-old patient with modified Fontan anatomy and pulmonary arteriovenous fistulae, in whom redirection of a previously placed hepatic venous-to-right pulmonary artery conduit was required in order to increase systemic arterial oxygen saturation. Revision of the conduit improved mixing of hepatic venous effluent with blood flow from the bidirectional Glenn shunt. Three years after this revision, the patient's oxygen saturation remained stable at 90%, and his physical activity was markedly improved. We present our rationale for selected redirection of the conduit and discuss other surgical options that can improve hypoxemia that is associated with pulmonary arteriovenous fistulae.

Complete unilateral leg duplication with ipsilateral renal agenesis.

UNLABELLED: A case of a 5-month-old infant with complete duplication of the right leg and ipsilateral renal agenesis is presented. There was also a duplicated scrotum, posterior urethral valves with hydronephrosis, abnormal pelvic bones, and a ventricular septal defect. Complete caudal duplication is exceedingly rare. Associated defects are common. Several aetiological theories have been proposed. Among them, an underlying polytopic (acro-renal) developmental field defect has been suggested. It best explains the specific findings in our patient. However, the aetiology of caudal duplication syndromes may be multifactorial. In the light of twinning theories, associated duplication of hindgut derivates should be suspected in similar cases. Further research is needed. The motor-skeletal functional outcome after leg duplication surgery is mostly favourable. CONCLUSION: A case of complete unilateral leg duplication with ipsilateral renal agenesis is presented. It appears to support the theory of a polytopic developmental field defect.

Analysis of pulmonary vascular response to acute alveolar hypoxic challenge in young rabbits subjected to chronic hypoxia from birth.

Chronic alveolar hypoxia induces vascular changes leading to pulmonary hypertension. We investigated the role of nitric oxide synthase (NOS) on basal pulmonary artery pressure (PAP) and on changes in PAP arising from an acute alveolar hypoxic challenge (AAHC) in normoxic and chronically hypoxic young rabbits. The chronically hypoxic rabbits were raised from birth in a chamber containing a (10% O2 + 90% N2) gas mixture, whereas the normoxic rabbits were kept in room air. The age of the animals at the time of study (approximately 38 days) was not significantly different between the 2 groups of rabbits. The in vivo PAP was measured using a right heart catheterization technique while the rabbits were spontaneously breathing either a hyperoxic or a hypoxic gas. In the chronically hypoxic group, the AAHC (hypoxic gas) produced a modest increase in PAP. However, after intravenous administration of (100 mg/kg) of the NOS inhibitor, L-NAME (N-nitro-L-arginine methyl ester), a marked increase in PAP was observed when these rabbits were rechallenged with the AAHC. In contrast, in the normoxic rabbits, the AAHC produced only a small increase in PAP, even after pretreatment with L-NAME. In both groups of rabbits, L-NAME led to a significant rise in basal PAP. Using Western blot analysis, we found endothelial NOS (eNOS) protein expression to be significantly increased in pulmonary artery and right ventricular myocardium of the chronically hypoxic rabbits. These results suggest that release of nitric oxide is involved in regulating basal PAP and in modulating the hypoxia-induced pulmonary vasoconstrictor response in immature animals. Moreover, eNOS appears to undergo up-regulation as a consequence of chronic hypoxia.