Contrast-enhanced ultrasound with SonoVue in the evaluation of postoperative complications in pediatric liver transplant recipients.

PURPOSE: To evaluate the utility of contrast-enhanced sonography in the study of pediatric liver transplant recipients and its potential impact in reducing the need for invasive diagnostic procedures. MATERIALS AND METHODS: From October 2002 to December 2003 we performed routine color Doppler ultrasound and contrast-enhanced ultrasound studies on 30 pediatric patients who had undergone liver transplantation. Findings indicative of complications were confirmed with invasive studies (angiography, computed tomography, and PTC). RESULTS: Contrast-enhanced sonography correctly identified four of the five cases of hepatic artery thrombosis and all those involving the portal (n = 6) and hepatic vein (n = 3) thrombosis. It failed to identify one case of hepatic artery thrombosis characterized by collateral circulation arising from the phrenic artery and the single case of hepatic artery stenosis. The latter was more evident on color Doppler, which revealed a typical tardus parvus waveform. The use of contrast offered no significant advantages in the study of biliary complications although it did provide better visualization of bile leaks. CONCLUSIONS: Contrast-enhanced sonography improves diagnostic confidence and reduces the need for more invasive imaging studies in the postoperative follow-up of pediatric liver transplant recipients.

Hyponatremic hypertensive syndrome and massive proteinuria in a patient with renin-producing leiomyosarcoma.

We report a case of renin-producing leiomyosarcoma associated with the hyponatremic hypertensive syndrome and nephrotic-range proteinuria. Extremely high levels of active renin and, to a greater extent, of prorenin were found in plasma and tumor tissue. Immunohistochemical and in situ hybridization studies demonstrated that the neoplastic cells were the source of renin production. The hyponatremic hypertensive syndrome and proteinuria promptly responded to treatment with angiotensin-converting enzyme inhibitors, suggesting an angiotensin II dependency of these disorders. After removal of the leiomyosarcoma, plasma concentration of active renin, but not of prorenin, normalized and the hypertension, proteinuria, and electrolyte abnormalities disappeared. However, 5 months after operation, the patient presented once again with hypertension, hypokalemia, proteinuria, and markedly increased plasma levels of both active renin and prorenin that heralded the relapse of neoplastic disease.

Post-transplant renal artery stenosis: the hemodynamic response to revascularization.

BACKGROUND: Percutaneous transluminal angioplasty and stenting are relatively noninvasive approaches to treat post-transplant renal artery stenosis. However, the real impact of this procedure on renal function recovery has never been quantitated precisely to date. METHODS: In eight consecutive renal transplant patients with renal graft artery stenosis, blood pressure, body weight, and anatomical, functional, and Doppler ultrasound parameters were evaluated before and one month after renal artery transluminal angioplasty and stenting. On both occasions, glomerular filtration rate and renal plasma flow were evaluated by inulin and paraaminohippuric acid renal clearances, and glomerular size-selective function was evaluated by the fractional clearances of neutral dextran macromolecules. RESULTS: The correction of renal artery stenosis, by normalizing renal vascular resistances, fully restored kidney perfusion and decreased arterial blood pressure, relieved water and sodium retention, restored an almost laminar arterial blood flow, and normalized vascular shear stress without appreciable effects on glomerular barrier size-selective function and proteinuria. Preangioplasty and postangioplasty renal resistive indices and peak systolic blood velocity estimated by Doppler ultrasounds were significantly correlated with the effective renal plasma flow and the blood velocity calculated at the site of stenosis. All patients were discharged without sequelae one or two days after angioplasty. CONCLUSIONS: Percutaneous transluminal angioplasty and stenting are safe and effective procedures to normalize the functional changes sustained by hemodynamically significant artery stenosis after renal transplantation. Doppler ultrasound scanning is a reliable and reproducible technique to monitor the renal functional response to vascular reperfusion.