Renal function with LVADs

KIDNEYS VS LVADS:

CAN WE WORK

TOGETHERRenal Grand

Rounds

Ahad Lodhi

Disclosure:

• None of my financial holdings influence this presentation

directly or indirectly.

Outline:

• Problem & need

• Basic types of VADs (Ventricular assist devices)

• Preimplantation/Baseline renal function and outcomes

• Continuous flow VADs and renal function

• AKI post VAD

• Improvement in renal function post VAD

• RRT in VAD patient

• Modalities

• Access

• BP monitoring

• Pump speed, Flow, Pulsatility Index

Outline:

• Problem & need• Basic types of VADs (Ventricular assist devices)

• Peri-implantation/Baseline renal function and outcomes


• AKI post VAD



• Modalities

• Access

• BP monitoring


Problem:

• >5.7 Millions Americans living with heart failure

Renal impairment is an independent predictor of mortality in HF patients

Every 1ml/min decline in CrCl below 60ml/min, increases mortality by 1%

Problem

44% CKD 3

14% CKD 4

7% CKD 5

Need for LVADs

• >50% mortality in advanced heart failure

• <3000 donors available per year

• LVADs provide improved survival in advance heart failure

• BTT (bridge to transplant) FDA approved

• DT (destination therapy) FDA approved

• BTR (bridge to recovery)

• Biventricular devices as BTT or BTR

• INERMACS (Interagency Registry for Mechanical

Assisted Circulatory Support)- 4311 LVADs June 2006-

Sept 2011 (1500/yr)

LVADs provide improved survival in

advance heart failure

• REMATCH Trial (2001): , 52% vs 25% at 1 yr

• Recent Trials (Starling et al 2011, Park et al 2012) survival

rates 73% DT and 85% BTT

Outline:

• Problem & need




• AKI post VAD


• RRT in VAD patient• Modalities

• Access

• BP monitoring


Types

• Pulsatile devices (First Gen)

• Thoratec Paracorporeal, Thoratec implantable, Heartmate Vented

• Chambers filled with blood and pneumatic mechanism emptying

the chambers via one way valve

• Continuous Flow devices

• Newer

• Axial and centrifugal flow design

• HeartMate 2, Jarvik 2000, HeartWare

• Smaller, quiter, less thrombogenic, improved survival, less

arrhythmias, less Rt HF and Resp failure.

• 95% of all LVADs Jan 2010-June 2011 (INTERMACS)

4 min Videos (2+2)

• Heartware

• http://youtu.be/v8aIeoHXTMw

• HeartMate 2

• http://youtu.be/YBxDhUzSrsk

http://youtu.be/v8aIeoHXTMw

http://youtu.be/YBxDhUzSrsk

Outline:

• Problem & need




• AKI post VAD



• Access

• BP monitoring


Preimplantation/Baseline renal function

and outcomes• Early studies with pulsatile flow associated high mortality

(75-100%) with preimplantation Renal dysfucntion.

• Recent with continuous flow:

• Sander et al, reported improved survival (1-3-6month) and

BTT rates when preimplantation gfr >60ml/min/1.73m2

• Yoshioka et al reported 30day, 90 day and 1 yr survivals

of 96%, 88% and 77% when Cr is <1.96 mg/dL

• Iwashima et all, suggest 2 week post-implantation gfr of

>82ml/min is stronger predictor of survival

• Intrinsic renal disease associated with worst outcomes.

Outline:

• Problem & need




• AKI post VAD



• Access

• BP monitoring


Continuous flow VADs and renal function

• Still some pulsatility due to intrinsic LV function

• Increased diastolic pressure and decreased peak systolic

pressure and increased laminar flow, ? More stasis distal

to atherosclerotic lesions ? Cortical blood flow

• Animal studies : renal arterial smooth muscle hyperplasia,

peri-arterial inflammatory cells, Inc PRA, inc Ang 2 recp

and ACE.

• Hasin et al, Initial improvement in gfr (53-87) , later stable

or slow decline?

• Greater decline in renin & aldosterone levels with pulsatile

flow, long term implications?

Outline:

• Problem & need




• AKI post VAD• Improvement in renal function post VAD


• Modalities

• Access

• BP monitoring


• Survival curves are similar in patient with and without AKI

extending from 1-7 Yrs

http://dx.doi.org/10.1016/j.healun.2005.11.457

Outline:

• Problem & need




• AKI post VAD

• Improvement in renal function post VAD• RRT in VAD patient

• Modalities

• Access

• BP monitoring


Improvement in renal function post VAD

• Due to? Improved flow, decrease congestion—dec

resistance, Dec activation of RAAS and sympathetic

systems.

• Improvement has been reported in upto 74% of patients

with baseline CKD…….how severe, acute or chronic

• Those who improve have better survival

• Patients who recover post-implant vs Pt without

dysfunction preimplant: no difference in survival curves, at

6 months, until transplanted and 1 yr post Txp.

• Patients with baseline chronic RD and diabetics are less

likely to recover significant renal function

Factors

• Pre-existing RD, various causes including HTN

• ongoing severe disease with MOF,

• residual damage from AKI,

• Renovascular Dz (atheroembolic)

• DM

• long standing low flow state

Effects Txp eligibility (can improve or worsen)

Use of CNIs

RRT IN LVAD PATIENTS

Modality:

• In acute settings: CRRT, once hemodynamically stable

can transition to IHD.

• PD:

• was not possible in older devices were large and were also

sometimes, implanted in peritoneal cavity or abd wall. Peritonitis

can be life threatening in this situation.

• Devices casuing hernia, bowel obs and erosion

• New devices can be implanted intra-pericardial or pre-peritoneal

• Gentle UF, less risk of bacteremia and device contamination and

it’s a home modality.

• Placing LVADs for in-center HD is a challenge in itself.

Vascular access

• All opinions and no Data:

• Suggest using ultrasound doppler to access patency in

both kind of AV access due to lack of pulsatile flow hence

lack of or poor bruit and thrill

• Most have suggested to use AV grafts as long as patient

is on LVAD.

• Does not need to mature and can be used very early, hence not

requiring catheter and risking bacteremia—pericardial and device

infection.

• AVFs need maturation , very poor maturation due to lack of

pulsatile flow.

• Usually less thrombosis as these patients are maintained on

systemic anticoagulation.

BP monitoring

• Difficult to use standard techniques and standard

automated devices (usually read if PP >15mmg,

oscillometric, significantly lower than arterial)

• Pulse Pressure in LVAD: Pump speed, native function,

Aortic valve stiffness, pre/afterloads.

• Doppler audible USG: Deflate the cuff, start of blood flow,

heard by Doppler, usually is the mean arterial BP

• High BP—increased afterload– retrograde flow through

valveless system—bad

• Optimal MAP 70-80mmHg

• Avoid –ve inotropes, first target RAAS

Pump Speed

• Rate of revolution, usually 8000 to 10000rpm

• Increase pump speed, incvacuum effect on left ventricle, faster and complete unloading & collapse of left V and even left atrium—not enough LVEDP to open aortic valve---Prolonged AV closure---stasis/Clot—also lead to coronary thrombosis

• Hemolysis, Platelet activation, septal shift to left with dec RVF

Pump Flow

• Flow 3-10L/min = cardiac output

• Derived from speed

Pulsatility Index

• Pulsatility of blood flow through the LVAD

• Depends on native LV function (contractility and flow)---

which depends on * preload & * pump speed.

• It can serve as an indicator for UF during CRRT.

• More UF, decrease preload, decreased PI, increase LVAD support

needed to maintain flow.

• It can be considered a surrogate marker for LVAD support

provided to maintain cardiac out put.

• Poor native LVF, decreased PI, increased LVAD support needed to

maintain flow and vice versa.

Pulsatility Index

Others

• Hemolysis/TMA

• Anticoagulation

• Bleeding.

Health & Medicine

Renal function with LVADs