MR scans during dialysis reveal impact of treatment on the heart

December 07, 2016
by Lisa Chamoff, Contributing Reporter
A first-of-its-kind study using MR scans during dialysis shows the impact that the treatment can have on the heart, including reductions in blood flow, leading to permanent heart damage. The risk is the same for standard hemodialysis (HD) and hemodiafiltration (HDF), during which patients are given replacement fluid.

For the study, published in the Journal of the American Society of Nephrology, researchers from the University of Nottingham’s Sir Peter Mansfield Imaging Centre and the Centre for Kidney Research and Innovation conducted MR scans on 12 patients undergoing both HD and HDF. The researchers measured cardiac index, stroke volume index, myocardial strain, coronary artery flow and myocardial perfusion.

All patients experienced segmental left ventricular dysfunction, in proportion to the amount of fluid that was removed from their body, the researchers found. Myocardial perfusion, or blood flow, decreased significantly during both treatments.

The dialysis treatments were done in the MR research center and special considerations needed to be taken in order to perform the scans. The needles had to be changed from metal to non-magnetic silicone ones and the lines that connect the patient to the dialysis machine had to be extended and insulated.

“Over the last 10 years or so, an increasing body of work has demonstrated how the stress that dialysis exerts on the circulation can result in reductions in blood flow to the heart muscle,” Dr. Nicholas Selby, an associate professor of nephrology at University of Nottingham told HCB News via email. “Previous work has mostly used echocardiography to detect this, but has limitations in terms of image quality and inability to directly measure several of the important changes. We therefore wanted to pursue the use of MR, despite the technical challenges, because MR is the only imaging modality that can provide a complete and simultaneous assessment of cardiac morphology, cardiac output, global/regional contractile function, fibrosis, coronary artery flow and contrast-free measurement of myocardial perfusion.”

The reduced blood flow usually doesn’t cause any symptoms, so patients may not be aware of it, Selby said. If this happens repeatedly it can result in permanent heart damage.

The study emphasizes the need to improve dialysis treatment by avoiding falls in blood pressure and reducing ultrafiltration, or the amount of fluid being removed, Selby said. Cooling of the dialysis fluid may also help.

“Whilst our study did not show benefit of HDF over standard dialysis, the technique of intradialytic MR can now be used to study other interventions that may improve dialysis” Selby said.