LVAD & Kidney Dysfunction: The Chicken & the Egg

• Some studies show that
  patients with low GFR prior to LVAD had initial improvement in creatinine but a
  gradual decline in GFR over the next several months. Despite this, GFR at one
  year was still more than the pre-LVAD level. Interestingly patients with normal
  pre-LVAD GFR had a small but steady decline in kidney function after the
  implantation. Probable reasons for the late decline in kidney function could due
  to a measurement bias (less muscle mass at the time of LVAD surgery, so low
  creatinine levels post LVAD, muscle mass improves with
  rise in creatinine), hemolysis or RV dysfunction (seen in up to 10 % patients post–LVAD). 
• Another unique possibility is an effect of continuous flow physiology
  on renal vessel walls (animal studies show arterial smooth muscle hyperplasia, periarteritis
  and interstitial inflammation & fibrosis; no human data). Bresco et al, demonstrated
  an unexpected survival analysis based on GFR change in first month of LVAD
  implantation. They showed that patients who had greater than 88 % rise in GFR within one
  month had a poor survival rate, followed by patients with any degree of
  worsening of kidney function after LVAD implantation. The best survival was in
  patients with modest GFR improvement (22-47%). One possible explanation for
  this could be that patients who are severely ill prior to LVAD are likely to be
  those with worse kidney function. Could they then have a larger improvement in kidney perfusion and therefore kidney function, in the early post
  LVAD period?

Dialysis Post LVAD:

• imaging of the abdomen should
  be done prior to PD catheter insertion to confirm that no element of LVAD is
  intra peritoneal
• PD catheter exit site should be far away from the drive
  line exit site.

• For catheter
  insertion, we need to remember not to reverse the anticoagulation in these
  patients. The person doing the cannulation should be trained to do the
  intervention in a fully anticoagulated individual. It’s always prudent to use
  fluoroscopy for these procedures as it reduces the risk of complications, like
  a guide wire inadvertently damaging the VAD pump. It’s important to perform the
  procedure under aseptic conditions and avoid bedside procedures. Tunneled
  catheters are preferred in this regard as they are associated with less risk of
  infections. If we are forced to do the cannulation without fluoroscopy
  guidance, it`s preferable to use a short guide wire (10-12 cm).
• Long term access should be
  a fistula or graft if possible. There are no direct studies comparing these 2 accesses.
  While the initial preference was for graft due to concerns of poor fistula
  maturation with the continuous flow, there are published
  cases of patients who had successful fistula creation while on LVAD. Of the
  6 cases described, 2 of them required
  balloon assisted maturation and the other 4
  had unassisted maturation which were successfully cannulated. The more
  difficult aspect of long term access is a thrill or bruit cannot be appreciated
  in these patients. The only way of assessing patency of the access is with the
  help of Doppler or direct cannulation.
• Very few case series of
  patients on HD have been described. One of them
  included 10 patients who underwent 281 sessions of HD after post-LVAD AKI. 15
  of these sessions were interrupted with symptomatic hypotension being the
  reason in 6 instances (3 catheter related blood stream infections; 3 volume
  related).
• Dialysis centres accepting
  patients on LVAD for HD should have their nurses and doctors trained to
  interpret the basic LVAD parameters and make necessary changes to hemodialysis
  prescription accordingly. Specifics about BP measurement were described in part
  1 of this post.