Experience with the Rex shunt (mesenterico-left portal bypass) in children with extrahepatic portal hypertension.

BACKGROUND/PURPOSE: Extrahepatic portal vein thrombosis (EPVT) in children can lead to severe bleeding from gastrointestinal varices, ascites, thrombocytopenia from hypersplenism, and other coagulation disorders. The authors have used the superior mesenteric vein to intrahepatic left portal vein (Rex) shunt in 5 children with symptomatic EPVT and report their results with this novel technique. METHODS: Children with symptomatic portal hypertension were screened for the underlying cause. All children with essentially normal livers and obstruction of the extrahepatic portal vein were considered for the Rex shunt. Evaluation included liver function tests, liver biopsy, and radiological evaluation of the intrahepatic vascular anatomy. RESULTS: Five patients between the ages of 2.8 and 10.5 years underwent evaluation for portal hypertension secondary to extrahepatic portal vein obstruction. Three patients had idiopathic extra hepatic portal vein thrombosis with cavernous transformation, 1 had thrombosis after a living-related liver transplant, and 1 had compression and obstruction of the main portal vein from enlarged lymph nodes after treatment of systemic histoplasmosis. All patients were symptomatic. Three patients had intermittent bleeding from esophageal and gastric varices, and all 5 had relative degrees of hypersplenism with enlarged spleens and thrombocytopenia (11,000 to 77,000). Three patients had significant leukopenia. Results of imaging studies suggested that 3 patients had inadequate intrahepatic portal veins for shunting, but all patients at exploration underwent successful shunting. There were no serious intraoperative complications. Postoperative complications included ascites in 2 patients that resolved within 1 month. There were no early shunt thromboses. The median postoperative length of stay was 7 days. Clinical follow-up ranged from 7 to 21 months. Gastrointestinal bleeding did not recur in any patient, and ascites resolved in all. Spleen size decreased significantly (P < .01) from 9.4 +/- 4.0 cm to 5.0 +/- 3.7 cm below the left costal margin. Mean platelet count and white blood cell count rose after shunting from 79 +/- 42 to 176 +/- 73 (P < .02) and 5.4 +/- 2.3 to 7.5 +/- 3.9 (P = .06), respectively. All shunts were studied at 1 and 7 days, and 3 and 6 months after the procedure. Shunt patency was documented in all cases. Subsequently, shunt blockage occurred in 2 patients. CONCLUSIONS: The Rex shunt has proven to be an effective method of resolving portal hypertension caused by EPVT including thrombosis after living donor transplantation. This shunt is preferable to other surgical procedures because it eliminates portal hypertension and its sequelae by restoring normal portal flow to the liver.

Contractile properties of intralobar pulmonary arteries and veins in the fetal lamb model of congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Pulmonary hypertension plays a significant role in the pathophysiology of congenital diaphragmatic hernia (CDH). Although there has been an intensive research effort directed at mediators that may cause pulmonary vasoconstriction, no single agent has been identified. The authors hypothesize that there may be an alteration in the cGMP-nitric oxide (NO) pathway of vasodilatation contributing to the pulmonary hypertension observed in CDH. The purpose of these studies is to begin to elucidate vasoactive properties of pulmonary vessels with particular attention to the cGMP-NO pathway of vasodilatation in fetal lambs with CDH. METHODS: Fourth-generation pulmonary arteries and pulmonary veins were dissected from both right and left lungs of eight, 139-day gestational fetuses with surgically created CDH. Vessels were studied with standard isolated tissue bath techniques. Experiments examined basal release of NO in endothelium-intact PVs and PAs of both right and left lungs by measuring the contractile force of vessels constricted with norepinephrine (NE) in the presence and absence of the nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine (L-NA). Concentration-response curves to the vasodilating agents zaprinast and A23187 were also obtained in vessels contracted by NE. RESULTS: Left and right pulmonary artery responses to NE are enhanced over those of historic controls. Pretreatment of left pulmonary arteries with L-NA enhances the vasoconstrictor response to NE, whereas right PAs show no increased response. Relaxation responses to A23187 and zaprinast, in both left and right pulmonary arteries were not different from control lambs. Relaxation responses of both left and right pulmonary veins to A23187 and zaprinast are blunted compared with controls. This blunting is significantly more in left pulmonary veins than right. Further, right but not left pulmonary veins display enhanced vasoconstrictive response to NE after L-NA pretreatment. CONCLUSIONS: The NO-cGMP pathway of vasodilatation is abnormal in the near term, fetal lamb with CDH. These abnormalities were most apparent in pulmonary veins and may reflect abnormal NOS activity or content between left and right lungs of the fetal lamb with CDH. Pulmonary arteries from CDH lambs have basal and stimulated NO release equal to that of historic controls but appear to be hypersensitive to exogenous vasoconstrictors.

Cervical ECMO cannula placement in infants and children: recommendations for assessment of adequate positioning and function.

BACKGROUND/PURPOSE: Cervical extracorporeal membrane oxygenation (ECMO) cannula position is often difficult to confirm by chest x-ray alone. Malposition requires a second surgery to rectify the problem. Reoperation places the patient at risk for infection, bleeding, or death. This study analyzes indications for cannula repositioning and suggests an alternative standard for intraoperative evaluation of catheter function as it relates to position. METHODS: The authors reviewed charts of 73 patients placed on arterio-venous ECMO through cervical vascular access. Reasons for repositioning of either cannula at the initial surgery or postoperatively were recorded. RESULTS: Of 73 patients, 18 (24.6%) required either arterial cannula or venous cannula repositioning. In 10 (55%) of these patients, cannula malposition was not detected by chest x-ray during the initial cannulation, and they therefore required a second cervical exploration for repositioning. CONCLUSIONS: Chest x-ray is not sensitive in demonstrating malpositioned cervical ECMO cannulae. Two-dimensional ECHO before wound closure, may be a superior, more cost effective means of assessing cannula placement and function than x-ray alone. Confirmation of cannula position and function, before wound closure, would reduce the risks involved with cervical reexploration.

Effectiveness of cholecystokinin-stimulated cholescintigraphy in the diagnosis and treatment of acalculous gallbladder disease.

We retrospectively reviewed the medical records of 107 patients in two community hospitals who had undergone cholecystokinin-stimulated cholescintigraphy with ejection fraction to determine whether this test is reliable in identifying patients whose symptoms will improve following cholecystectomy. Patients with cholelithiasis or incomplete medical records and patients who could not be interviewed were excluded from the study. Forty-two of 58 study patients (72%) had an abnormal ejection fraction (defined as 35% or less); 27 of 42 patients (64%) underwent cholecystectomy. Twenty-six of 27 (96%) reported lessening of or resolution of symptoms following cholecystectomy. Sixty-seven per cent of the surgical specimens from the 27 patients demonstrated chronic cholecystitis. Fifteen of 42 patients (36%) with abnormal ejection fractions did not undergo cholecystectomy; 12 of 15 (80%) also reported lessening or resolution of symptoms. Of the 16 of 58 patients with a normal ejection fraction, 2 underwent cholecystectomy and reported resolution of symptoms. Five of 14 (36%) with normal ejection fractions who did not undergo cholecystectomy reported improvement. In this series, most patients with an abnormal ejection fraction had lessening of symptoms regardless of whether they underwent cholecystectomy.