case study
Aquapheresis™ in
the Early Post-Operative Period in a Patient Receiving an LVAD as
a Bridge to Transplantation
Introduction
Patients with end-stage heart failure secondary to either ischemic
or idiopathic cardiomyopathy frequently demonstrate worsening renal
function prior to initiating mechanical circulatory support. Extended
cardiopulmonary bypass times and large post-operative transfusion
requirements contribute to the development of third space fluid
retention often seen in this population. Additionally, diuretic
response can be extremely variable in the early post-operative period
in these patients. This report describes the use of aquapheresis/ultrafiltration
in the early post-operative period in a patient receiving an LVAD
as a bridge to transplantation.
Patient History
A 61 year old male with ischemic cardiomyopathy listed as status
lb on our transplant waiting list presented with decompensated congestive
heart failure despite chronic Milrinone infusion. The patient had
insertion of a Swan-Ganz catheter and augmentation of his inotropic
support with the addition of Dobutamine. Attempts to diurese the
patient with loop diuretics initially were effective with some decrease
in the patient’s pulmonary artery wedge pressure. However,
after 72 hours he became refractory to diuretics and demonstrated
continued decompensation with reduced cardiac output and serum sodium
levels as well as a rising serum creatinine level.
At this point, the decision was made to implant
an LVAD as a bridge to transplantation. The patient had a cardiopulmonary
bypass time of 225 minutes. Multiple rounds of platelets and fresh
frozen plasma were transfused in the early post-operative period
to control bleeding and correct his coagulopathy. On post-operative
day number one, the patient was found to be 9 Kg over his preoperative
weight. Additionally, he was demonstrating moderate to severe right
ventricular dysfunction with central venous pressures running in
the range of 20 to 24 mmHg. Diuresis was attempted for 24 hour using
a continuous infusion of loop diuretics without significant response.
On postoperative day number two, aquapheresis was
begun using the CHF Solutions Aquadex FlexFlow through a subclavian
vein central line. Initial volume removal goals were an average
of 150 to 200 cc of fluid removal every hour. Treatment lasted approximately
24 hours with nearly 6 liters of fluid removed. The patients’
central venous pressures decreased to 12 to 15 mmHg and inotropic
support was able to be weaned. The patient tolerated aquapheresis
well with stable hemodynamics and LVAD flow rates in the range of
5 to 5.5 liters per minute.
This patient was ultimately successfully transplanted
and currently maintains normal renal function.
Discussion
Decompensated congestive heart failure is typically characterized
by a constellation of findings including reduced cardiac output,
volume overload, decreased systemic perfusion, and worsening renal
function. Reduced renal perfusion leads to activation of the Renin-Angiotensin-Aldosterone
System (RAAS), which in turn causes salt and water retention, expansion
of intravascular volume and exacerbation of CHF.
While, diuretic therapy has been a mainstay in the
treatment of end stage congestive heart failure, many patients become
resistant to diuretic therapy with prolonged exposure. Additionally,
loop diuretics have been shown to decrease glomerular filtration
rate in patients with heart failure making adequate fluid removal
in the face of decompensation difficult [1].
Patients requiring LVAD placement for bridge to
transplantation are characterized by continued hemodynamic deterioration
and organ function despite maximal medical therapy [2]. Given time,
ventricular support can reverse the end organ ischemic insult seen
in these patients. However, in the early post-operative period these
patients still have profound RAAS activation in addition to elevated
levels of neurohormones that in combination can make diuretic responsiveness
unpredictable [3].
We have found that aquapheresis with the CHF Solutions’
Aquadex FlexFlow to be a safe and effective technique for volume
reduction in the early post-operative period in these patients.
This technique is well tolerated hemodynamically, and does not appear
to affect the performance of the LVAD in regards to cardiac output
or stroke volume.
Case history courtesy of:
Todd Dewey, M.D.
Cardiothoracic and Transplant surgeon
Medical City Dallas Hospital
Dallas, Texas
References:
1. Butler J, Forman DE, Abraham WT, et al. Relationship
between heart failure treatment and development of worsening renal
function among hospitalized patients. Am Heart J 2004 Feb;147(2):193-4.
2. Oz MC, Goldstein DJ, Pepino P, et al. Screening scale predicts
patients successfully receiving long-term implantable left ventricular
assist devices. Circulation 1996 Nov 1;92(9 suppl):II169-73.
3. James KB, McCarthy PM, Thomas JD, et al. Effect of the implantable
Left Ventricular Assist Device on Neuroendocrine Activation in Heart
Failure. Circulation 1995;92:II191-195.
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