Abstract 330: Blood Oxygen Level Dependent (BOLD) MR evaluation of renal oxygenation is unaffected by water loading in atherosclerotic renovascular disease
Background: Renal hypoxia is a complex function of post-glomerular medullary blood flow, active solute transport and is considered a major risk element for acute kidney injury. Previous studies indicate that sodium balance, diuretic administration and some drugs affect tissue oxygenation. Water loading in younger subjects lowers medullary deoxyhemoglobin. We sought to evaluate the effects of water loading on the day of BOLD imaging in older subjects undergoing protocol evaluation of atherosclerotic renovascular disease (ARVD).
METHODS: Inpatient studies were performed in patients with hemodynamically severe ARVD (n=15, Doppler US velocity >270 cm/sec), during 150 mEq Na+ intake and ACE/ARB Rx. Two groups were studied: Group A (n=10) received oral water loading (20 ml/kg), whereas Group B (n=5) had none. Tissue R2* (index of deoxyhemoglobin levels) and fractional kidney hypoxia (medullary estimate) (% of renal coronal area with R2*>20/s) were measured in stenotic kidneys by BOLD-MRI at 3T, before and after IV injection of Furosemide (20gm).
RESULTS: Cortical R2* and fractional tissue hypoxia were similar for the 2 groups (P =0.6 and 0.7). Both groups reduced cortical R2* and fractional hypoxia after furosemide injection to the same degree. Table
CONCLUSION: These data demonstrate that water loading on the day of BOLD evaluation in older subjects with ARVD does not materially alter cortical or medullary estimates of oxygenation. Our results extend previous studies indicating that water loading in older individuals fails to alter medullary oxygenation unlike alterations in sodium intake, diuretic administration or blockade of the renin-angiotensin system.
Author Disclosures: A. Saad: None. S. Herrmann: None. J. Glockner: None. L. Lerman: None. S. Textor: None.
- © 2014 by American Heart Association, Inc.