Delayed presentation of traumatic aortocaval fistula: a report of two cases and a review of the associated compensatory hemodynamic and structural changes.

Chronic aortocaval fistula (ACF) is a rare complication of gunshot wounds to the abdomen. Herein we report two cases of traumatic ACF: one asymptomatic and the other presenting with congestive heart failure (CHF) 20 and 30 years, respectively, after their initial injury. The recent onset of CHF, the presence of a continuous abdominal bruit, and, in the second patient, a history of penetrating trauma suggested the diagnosis of ACF. The diagnosis was confirmed by computed tomography scanning in both patients. Surgical repair of the ACF in the symptomatic patient resulted in resolution of the CHF and reversed the dilatation of the aorta and inferior vena cava. The asymptomatic patient was lost to follow-up. CHF in a young male patient with a history of penetrating abdominal trauma should alert the surgeon to this rare complication.

Estrogen blocks homocysteine-induced endothelial dysfunction in porcine coronary arteries(1,2).

BACKGROUND: The objective of this study was to examine the effect of estrogen combined with homocysteine on vasomotor function and endothelial integrity in intact porcine coronary arteries. MATERIALS AND METHODS: Pig coronary artery rings were incubated with estrogen, homocysteine, or estrogen and homocysteine for 24 h. Myographic analysis was performed with thromboxane A2 analog U46619 for contraction and bradykinin or sodium nitroprusside for relaxation. Endothelial nitric oxide synthase (eNOS) levels were determined by immunohistochemistry. Levels of superoxide anion were assessed by lucigenin-enhanced chemiluminescence analysis. RESULTS: Endothelium-dependent vasorelaxation (bradykinin) for the homocysteine alone group was 62% compared with control (P < 0.05), and endothelium-dependent vasorelaxation for the estrogen alone group was 85% compared with control (P > 0.05). Endothelium-dependent vasorelaxation for the estrogen-homocysteine combined group was 79% compared with 89% for control (P > 0.05). There were no differences in endothelium-independent vasorelaxation (sodium nitroprusside) or in smooth muscle contractility (U46619) between all three groups and control. In addition, the eNOS immunoreactivity was declined in the homocysteine group and had no major change in the estrogen or estrogen plus homocysteine-treated group as compared with controls. The superoxide free radical measurement showed a marked increase in the homocysteine group, no major change from controls in the estrogen group, and a much-lessened effect in the combination of estrogen and homocysteine. CONCLUSIONS: These data demonstrate that combining estrogen with homocysteine significantly blocks the effect of homocysteine on impairing endothelium-dependent vasorelaxation as well as on decreasing eNOS expression and increasing oxidative stress in porcine coronary arteries. This study suggests that estrogen may play a role in preventing homocysteine-mediated endothelial dysfunction and may be of benefit in the hyperhomocysteinemic patient.

Methemoglobinemia: an unusual cause of postoperative cyanosis.

Methemoglobinemia, although rare, must be considered in surgical patients presenting with acute respiratory distress and cyanosis. We report two cases of methemoglobinemia in patients undergoing aortic reconstruction. The first patient developed methemoglobinemia while on a nitroglycerin infusion, and the second after receiving benzocaine spray before intubation. Both patients were treated with methylene blue and ascorbic acid, with resolution of their hypoxia and cyanosis. The pathophysiology, etiology, diagnosis, and treatment of methemoglobinemia are reviewed.