Endovascular treatment of a hepatic artery pseudoaneurysm using a novel pericardium covered stent.

Visceral and renal artery aneurysms (VRAAs) and pseudoaneurysms are rare. Their increasing incidence is largely thought to be due to advances in medical imaging. Twenty percent of VRAAs occur in hepatic arteries, with approximately fifty percent of these represented by pseudoaneurysms, which are prone to spontaneous rupture. Many treatments for VRAAs exist, with the endovascular approach being favoured. Treatment aims to preserve visceral perfusion and exclude the aneurysm; however, complex aneurysms may require parent artery or end-organ sacrifice. Covered stents allow rapid aneurysm exclusion while preserving parent artery patency, a favourable outcome when parent artery or end-organ sacrifice is undesirable. The AneuGraft pericardium covered stent (PCS) combines the benefits of a low-profile covered stent with those of a low immunogenic material. We describe the endovascular treatment of a patient with a hepatic artery pseudoaneurysm, where parent artery sacrifice was considered unacceptable. The AneuGraft PCS was used to provide immediate and complete exclusion, with dual antiplatelet therapy for 1 week, followed by single antiplatelet use. The procedure was a technical success, with preservation of the hepatic arteries and complete exclusion of the pseudoaneurysm. There were no complications immediately following the procedure or on post-procedural follow-up. The pseudoaneurysm remained excluded at 6-week CT angiogram (CTA) follow-up. This case describes a safe and effective method for completely excluding a complex pseudoaneurysm, utilising the AneuGraft PCS, allowing for the potential management of a wider range of aneurysms with unfavourable morphology.

Regression of hepatocellular adenomas and systemic inflammatory syndrome after cessation of estrogen therapy.

We report a case of dramatic systemic inflammatory symptoms and biochemical signs of inflammation related to multiple hepatic adenomas that completely resolved after cessation of the oral contraceptive pill (OCP) and associated adenoma regression. This represents a case of dramatic symptoms that resolved after estrogen withdrawal alone. (Hepatology 2017;66:989-991).

Contrast-enhanced ultrasound evaluation of the renal microcirculation response to terlipressin in hepato-renal syndrome: a preliminary report.

BACKGROUND: Terlipressin improves renal function in some patients with type-1 hepato-renal syndrome (HRS). Renal contrast-enhanced ultrasound (CEUS), a novel imaging modality, may help to predict terlipressin responsiveness. OBJECTIVES: We used CEUS to estimate the effect of terlipressin on the renal cortical microcirculation in type-1 HRS. METHODS: We performed renal CEUS scans with destruction-replenishment sequences using Sonovue(®) (Bracco, Milano Italy) as a contrast agent at baseline and after the intravenous administration of 1 mg of terlipressin, in four patients with type-1 HRS. We analyzed video sequences offline using dedicated software. We derived a perfusion index (PI) at each time point for each patient. RESULTS: Patients 1 and 2 had severe presentation and were admitted to the intensive care unit. Both showed a marked increase in PI (+216% and + 567% of baseline) in response to terlipressin. Patients 3 and 4 had less severe presentations and had a decrease in PI (-53% and -20% of baseline) in response to terlipressin. Patients 1, 2, and 4, but not patient 3, responded to terlipressin therapy with a decrease in serum creatinine to <150 µmol/L. CONCLUSIONS: CEUS detected changes in renal cortical microcirculation in response to terlipressin and demonstrated heterogeneous microvascular responses to terlipressin. These initial proof-of-concept findings justify future investigations.

Contrast-enhanced ultrasonography to evaluate changes in renal cortical microcirculation induced by noradrenaline: a pilot study.

INTRODUCTION: We used contrast-enhanced ultrasound (CEUS) to estimate the effect of an increase in mean arterial pressure (MAP) induced by noradrenaline infusion on renal microvascular cortical perfusion in critically ill patients. METHODS: Twelve patients requiring a noradrenaline infusion to maintain a MAP more than 60 mmHg within 48 hours of intensive care unit admission were included in the study. Renal CEUS scans with destruction-replenishment sequences and Sonovue® (Bracco, Milano Italy) as a contrast agent, were performed at baseline (MAP 60 to 65 mmHg) and after a noradrenaline-induced increase in MAP to 80 to 85 mmHg. RESULTS: There was no adverse effect associated with ultrasound contrast agent administration or increase in noradrenaline infusion rate. Adequate images were obtained in all patients at all study times. To reach the higher MAP target, median noradrenaline infusion rate was increased from 10 to 14 µg/min. Noradrenaline-induced increases in MAP were not associated with a significant change in overall CEUS derived mean perfusion indices (median perfusion index 3056 (interquartile range: 2438 to 6771) arbitrary units (a.u.) at baseline versus 4101 (3067 to 5981) a.u. after MAP increase, P = 0.38). At individual level, however, we observed important heterogeneity in responses (range -51% to +97% changes from baseline). CONCLUSIONS: A noradrenaline-induced increase in MAP was not associated with an overall increase in renal cortical perfusion as estimated by CEUS. However, at individual level, such response was heterogeneous and unpredictable suggesting great variability in pressure responsiveness within a cohort with a similar clinical phenotype.

Contrast-enhanced ultrasound evaluation of renal microcirculation in sheep.

BACKGROUND: Contrast-enhanced ultrasonography (CEUS) is a novel imaging modality to estimate microvascular perfusion. We aimed to assess renal cortical microcirculatory changes by CEUS during pharmacologically or mechanically induced modifications of renal blood flow (RBF) in experimental animals. METHODS: We implanted invasive transit-time Doppler flow probes and a vascular occluder around the renal artery in six Merino sheep. After induction of general anaesthesia, renal CEUS studies with destruction-replenishment sequences were performed at baseline and after different interventions aimed at modifying RBF. First, we administered angiotensin II (AngII) to achieve a 25% (AngII 25%) and 50% (AngII 50%) decrease in RBF. Then, we applied mechanical occlusion of the renal artery until RBF decreased by 25% (Occl 25%) and 50% (Occl 50%) of the baseline. Finally, a single dose of 25 mg of captopril was administered. CEUS sequences were analysed offline with dedicated software and perfusion indices (PI) calculated. RESULTS: Pharmacological reduction of RBF with AngII was associated with a 62% (range: 68 decrease to 167 increase) increase (AngII 25%) and a 5% increase in PI (range: 92% decrease to 53% increase) (AngII 50%) in PI. Mechanical occlusion of the renal artery was associated with a 2% (range: 43% decrease to 2% increase) decrease (Occl 25%) and a 67% (range: 63% decrease to a 120% increase) increase (Occl 50%) in PI. The administration of captopril was associated with a 8% (range: 25% decrease to a 101% increase) decrease in PI. Pooled changes in PI failed to reach statistical significance. The study was limited by the difficulty to obtain high quality images. CONCLUSIONS: CEUS-derived parameters were highly heterogeneous in this sheep model. The current protocol and model did not allow the evaluation of the correlation between macro and microcirculation assessment by CEUS.

Contrast-enhanced ultrasound to evaluate changes in renal cortical perfusion around cardiac surgery: a pilot study.

INTRODUCTION: Contrast-enhanced ultrasound (CEUS) is a new technique that might enable portable and non-invasive organ perfusion quantification at the bedside. However, it has not yet been tested in critically ill patients. We sought to establish CEUS's feasibility, safety, reproducibility and potential diagnostic value in the assessment of renal cortical perfusion in the peri-operative period in cardiac surgery patients. METHODS: We recruited twelve patients deemed at risk of acute kidney injury (AKI) planned for elective cardiac surgery. We performed renal CEUS with destruction-replenishment sequences before the operation, on ICU arrival and the day following the admission. Enhancement was obtained with Sonovue® (Bracco, Milano, Italy) at an infusion rate of 1 ml/min. We collected hemodynamic parameters before, during and after contrast agent infusion. At each study time, we obtained five video sequences, which were analysed using dedicated software by two independent radiologists blinded to patient and time. The main output was a perfusion index (PI), corresponding to the ratio of relative blood volume (RBV) over mean transit time (mTT). RESULTS: All 36 renal CEUS studies, including 24 in the immediate post-operative period could be performed and were well tolerated. Correlation between readers for PI was excellent (R2 = 0.96, P < 0.0001). Compared with baseline, there was no overall difference in median PI's on ICU admission. However, the day after surgery, median PI's had decreased by 50% (P < 0.01) (22% decrease in RBV (P = 0.09); 48% increase in mTT (P = 0.04), both suggestive of decreased perfusion). These differences persisted after correction for haemoglobin; vasopressors use and mean arterial pressure. Four patients developed AKI in the post-operative period. CONCLUSIONS: CEUS appears feasible and well-tolerated in patients undergoing cardiac surgery even immediately after ICU admission. CEUS derived-parameters suggest a decrease in renal perfusion occurring within 24 hours of surgery.

Bench-to-bedside review: contrast enhanced ultrasonography--a promising technique to assess renal perfusion in the ICU.

Acute kidney injury (AKI) is common in critically ill patients and associated with important morbidity and mortality. Although alterations in renal perfusion are thought to play a causative role in the pathogenesis of AKI, there is, to date, no reliable technique that allows the assessment of renal perfusion that is applicable in the ICU. Contrast-enhanced ultrasound (CEUS) is an ultrasound imaging technique that makes use of microbubble-based contrast agents. These microbubbles, when injected into the bloodstream, allow visualization of vascular structures and, with contrast-specific imaging modes, detection of blood flow at the capillary level. Some recent CEUS-derived approaches allow quantification of blood flow in several organs, including the kidney. Current generation ultrasound contrast agents have strong stability and safety profiles. Along with post-marketing surveillance, numerous studies report safe administration of these agents, including in critically ill patients. This review presents information on the physical principles underlying CEUS, the methods allowing blood flow quantification and the potential applications of CEUS in critical care nephrology, currently as a research tool but perhaps in the future as a way of monitoring renal perfusion.

An assessment of the accuracy of renal blood flow estimation by Doppler ultrasound.

BACKGROUND: Knowledge of renal blood flow is considered important in the management of critically ill patients with acute renal failure. Renal Doppler ultrasound has been used to estimate renal blood flow. Its accuracy, however, has not been formally assessed. DESIGN: Prospective blinded animal study. SETTING: University physiology laboratory. SUBJECTS: Seven merino cross-ewes. INTERVENTIONS: We chronically implanted transit-time flow probes around the left renal artery and performed Doppler ultrasound measurements of RBF. We simultaneously recorded RBF values obtained with implanted flow probes and Doppler ultrasound during (a) observation, (b) dobutamine and (c) nitroprusside infusion in random order. RESULTS: In a total of 202 paired measurements, Doppler ultrasound measured peak systolic velocity (PSV) correlated very weakly with implanted flow probe measurements of RBF (r (2) = 0.015), as did end-diastolic velocity (EDV; r (2) = 0.086) and mean velocity (MV_vel; r (2) = 0.04). We also found similar weak correlations with other Doppler-ultrasound-derived indices. All comparisons showed bias and wide limits of agreement. CONCLUSIONS: Doppler-ultrasound-derived estimates of RBF show little correlation with transit-time flow probe measurements, display significant bias and wide limits of agreement and have low accuracy for clinically significant changes in RBF in large animals.