Duplex scan and histologic assessment of acute renal injury in a kidney-kidney crosstalk swine experimental model.

OBJECTIVE: The objective of this study was to identify the effect of two left renal vasculature occlusion strategies on the duplex ultrasound-assessed rheology and histology of the contralateral kidney. METHODS: Pigs were randomly assigned to one of two groups: left renal artery-only clamping (A group, n = 8) or left renal artery and vein clamping (AV group, n = 9). Bilateral renal parenchymal biopsy specimens were taken every 10 minutes for 90 minutes. Duplex ultrasound resistive index (RI) and pulsatility index (PI) were measured. Mixed models with normal distribution and first-order autoregressive correlation structure and generalized estimating equation models were used. Results are presented as adjusted means with standard errors, estimated proportions with standard errors, and line plots with 95% confidence intervals. RESULTS: RI and PI increased in the nonischemic kidney. In A group animals, RI values increased significantly (P < .01) after 30 minutes of ischemia and PI increased significantly (P < .04) from 30 to 60 minutes of ischemia. The number of histologic abnormalities was higher in A group than in AV group biopsy specimens. The percentage of lesions increased significantly after 10 minutes in A group nonischemic kidneys (P < .02) and between 50 and 80 minutes in AV group nonischemic kidneys (P < .01). CONCLUSIONS: Nonischemic kidneys were acutely affected by contralateral ischemia. Their function was more adversely affected by unilateral renal artery occlusion with preserved renal vein patency (A group).

Maternal venous hemodynamics assessment for prediction of preeclampsia should be longitudinal.

OBJECTIVE: To address the question whether maternal venous abnormalities exist at the onset of, or develop during the course of pregnancy. METHODS: We present five case reports of patients with early onset preeclampsia (EPE), late onset preeclampsia (LPE), gestational hypertension (GH), essential hypertension (EH) and an uncomplicated pregnancy (UP). Maternal renal and hepatic vein Doppler waves and maternal venous pulse transit times (VPTT) were assessed in early pregnancy and again shortly before delivery. RESULTS: In all cases, maternal VPTT were normal in early pregnancy and changed to abnormal values in EPE and LPE, which was not true for UP and GH or EH. CONCLUSION: These observations support the view that venous hemodynamic dysfunction of preeclampsia (PE) develops during the course of pregnancy. Therefore, assessment of an individual's venous function for prediction of PE should be serial and longitudinal.

Clinical significance and renal haemodynamics of incidentally detected retroaortic left renal vein: assessment with venous Doppler sonography.

The purpose of this study was to determine whether renal venous pulsations are affected by compression of the left renal vein (LRV) between the aorta and spine, and also to determine the clinical significance of incidentally detected retroaortic LRV. The study population was recruited from 783 consecutive patients undergoing abdominal CT examination for various indications. 22 patients with a retroaortic LRV were prospectively enrolled in this study, and 22 patients without renal disease served as a control group. After measuring the diameters of the central and peripheral portions of the LRV on CT images, the ratio (P/C) and difference (P-C) of the diameters were calculated. Doppler sonography of the interlobar arteries and veins of the left kidney was then performed to obtain impedance indices. Urine analysis of all subjects and scrotal colour Doppler ultrasound of male patients were also performed. The retroaortic LRV diameters were significantly narrower than the pre-aortic LRV diameters (p = 0.002). The left intrarenal venous impedance indices were significantly higher in the patients with retroaortic LRV (p = 0.026) and in the subgroups with P/C>2 (p = 0.020), with P-C>4 mm (p = 0.007) and without nutcracker-like associations (p = 0.006) than in control subjects, but no significant difference was noted between the arterial resistance indices. Haematuria (n = 8), proteinuria (n = 4), varicocele (n = 3) and collaterals (n = 1) were detected in the study group but not in the control group. In conclusion, incidentally detected retroaortic LRV appears to be associated with haematuria, proteinuria, varicocele and altered venous pulsatility. Further investigations are needed to understand the role of venous Doppler ultrasound in the nutcracker phenomenon.

Use of Doppler ultrasonography in the assessment of bronchodilator response in acute bronchiolitis.

Measurement of the response of acute bronchiolitis (AB) to bronchodilators relies on clinical signs and pulse oximetry. We hypothesized that Doppler ultrasonographic indices of hepatic venous flow may prove to be an objective tool in the assessment of the effect of inhaled salbutamol in infants hospitalized for AB. Previously healthy infants hospitalized for their first episode of AB were prospectively studied. Composite clinical score (CCS, retractions plus wheezing/crackles) and hemoglobin oxygen saturation (SaO(2)) were measured before, and 15-min post-salbutamol nebulization (0.15 mg/kg, minimum 1.5 mg). Peak velocities at the middle hepatic vein (PV-HV) and right renal vein (PV-RV), as well as peripheral-to-middle hepatic vein transit time (TT) of an ultrasound contrast agent were also measured by Doppler ultrasonography pre- and post-nebulization. Nineteen infants were studied. Mean CCS decreased by 0.37 (95% confidence interval [CI]: 0.08-0.66, P = 0.015) and mean SaO(2) increased by 0.68% (95%CI: 0.17-1.19, P = 0.01) post-bronchodilator treatment. Mean TT increased by 9.54 sec (95%CI: 5.95-13.13, P < 0.0001) and PV-HV increased by 16.49 cm/sec (95%CI: 9.07-23.91, P = 0.0002); PV-RV did not change. TT (r = 0.51, P = 0.009), but not PV-HV, correlated negatively with CCS. There was a strong positive correlation between pre- and post-salbutamol TT values (r = 0.92, P < 0.0001). The most likely explanation for these findings is post-salbutamol abolishment of shunting at the pulmonary capillary bed. We conclude that the peripheral-to-middle hepatic vein prolongation of TT measured by Doppler ultrasonography after salbutamol administration in infants with AB can be used as a bedside tool in the objective assessment of clinical response to medication in these patients.

Functional assessment of canine kidneys after acute vascular occlusion on Gd-DTPA-enhanced dynamic echo-planar MR imaging.

RATIONALE AND OBJECTIVES: To assess the alteration in renal transit of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in dog kidneys after acute vascular occlusion on dynamic echo-planar imaging (EPI). METHODS: Dynamic 240-ms EPI series (repetition time/echo time/inversion time [TR/TE/TI] = 3000/42.1/100 ms) of the midcoronal plane of both kidneys of dogs anesthetized by intravenous administration of phenobarbital sodium and ketamine hydrochloride were obtained before and after ligation of the left renal vein (n = 6) or artery (n = 6) for 40 minutes after a 2-second-rate bolus injection of a 0.05 mmol/kg dose of Gd-DTPA. Renal Gd-DTPA transit was analyzed on the time-DeltaR2* curves in each layer of the outer cortex (OC), juxtamedullary cortex and outer zone of the medulla (JMC-OM), and the inner zone of the medulla (IM). The results were compared with those in six normal animals and those of a fast gradient-echo T1-weighted dynamic study performed in other vein- (n = 6) or artery- (n = 6) occluded animals and six normal animals. The histopathological basis of the altered Gd-DTPA transit was also evaluated. RESULTS: The dynamic EPI showed rapid Gd-DTPA transit through each of the five concentric layers, with three separate peaks on the time-DeltaR2* curves. The vein-occluded kidneys showed immediate swelling, with a significant increase in the cross-sectional area proportion of the JMC-OM layer compared with normals (32% +/- 2% vs 24% +/- 2%, P < 0.0001) and intensely congested capillaries, tubular, obliterated material, and gradual and persistent enhancement of the OC and JMC-OM layers but poor Gd-DTPA migration to the IM layer. The artery-occluded kidneys showed a significant reduction in the entire cross-sectional area compared with normals (1352 +/- 69 vs 1432 +/- 47 mm(2), P < 0.05) and poor enhancement, with significant decreases in the area under the time-DeltaR2* curve of the OC and JMC-OM layers compared with the vein-occluded kidneys (79 +/- 50 vs 324 +/- 108 and 82 +/- 42 vs 326 +/- 113, respectively; both P < 0.0001), despite minimal histological damage. In both models, the nonaffected kidneys showed significant increases in the area under the time-DeltaR2* curves compared with baseline. The time course of vascular and tubular Gd-DTPA transit was more detailed by the EPI study than by the T1-weighted imaging study. CONCLUSIONS: Echo-planar imaging has an excellent ability to follow the rapid, renal Gd-DTPA transit through the regional anatomy of the canine kidney. After venous occlusion, the JMC-OM layer may be the most affected site, primarily causing renal swelling and interruption of tubular Gd-DTPA transit and concentration. In contrast, an initial block of vascular Gd-DTPA inflow is the primary effect of arterial occlusion. Nonaffected kidneys seem to compensate by increasing excretion of Gd-DTPA.