Circulatory Assist Devices

Andrew Rosenberg MDChief, Division of Critical Care Anesthesiology

Assistant Professor Anesthesiology & Internal MedicineMedicine

University of Michigan

Circulatory Assist

High

Low

Low High

CardiacAssist

Invasiveness

Inotropes

IABP

External cardiacassist (BVS 5000)

Implantable LVAD

TAH

Long term use of VADS

NEJM, 06

Future CVC

Research Bldg

CVC Level 5

Epidemiology of Heart Failure5 million Patients with CHF in US1% of population over 65 years old

160% increase in hospitalizations due to CHF CHF over past decadeSymptomatic CHF = 45% 1-year mortality. < half of 4200 patients on Tx list will receive a receive a heart Tx.

15%/year die waiting for organ

Case Study: Acute Cardiac FailureFailure

52 yo male Hx; CAD, HTN, now with large Anterior Wall Wall MI, Cardiogenic Shock, hypoxemic.VS; HR=105, BP=80/67, CI=1.5, PAOP=28,CVP=16Intubated, 100% Fi02Meds;

Dobutamine 12mcg/kg/min12mcg/kg/minMilrinone .375mcg/kg/min.375mcg/kg/minNorepinephrine .13mcg/kg/min

Oliguric, Rising creat, LFTs,, prothrombin time.

Circulatory Assist DevicesIABP (Intra-aortic, counterpulsation Balloon pumpsECLS (Extra-corporeal Life Support)

Cardio-pulmonary bypassECMO-cardiac {VA ECMO}

(VADS)Ventricular Assist DevicesMinimally invasiveBridge to recovery/transplantDestination therapies

IABPsIntroduced 1960’s.Most widely used mechanical circ. Support

deviceReduces cardiac work by ↓afterloadIncreases coronary blood flow

Indications;1. Cardiogenic shock

Fail to wean from CPBAcute MI

2. Acute mitral regurgitation3. Unstable angina4. Support during high-risk

procedures/eventsPTCAUnstable Pts. Prior to CPB.Ventricular arrhythmias refractory to Rx.

Contraindications;1. Aortic insufficiency2. Aortic dissection3. Prosthetic graft in thoracic

aorta4. Severe aortoiliac disease

Practical IABPSystolic time intervals used to coordinate patients electrical and mechanical events of cardiac cycle.Polyethylene balloon, mounted on hollow catheter(arterialpressure monitor) advanced to 2cm below left sublcavian artery30-40 cc volume displacementBalloon deflates at beginning of systole, increasing stroke volume by as much at 40%

↓ LV stroke work, 02 consumption.

Ballon inflates during diastole increasing coronary artery perfusion.

IABP; ComplicationAortic dissection or arterial perforationFailure to advance catheter beyond iliofemoral system due to atherosclerotic diseaseLimb ischemia requiring IABP removal

11-27%ThrombocytopeniaSepsisBalloon rupture w/ helium embolization (2%)

Heralded by high balloon inflation pressures, blood in connecting tubingtubing

HematomasPseudoaneurysmAV fistulas

IABP Consol Controls

IABP Waveforms Early Inflation

Late Inflation

Slow Deflation

Abrupt Deflation

ECMO Setup

ECLS CircuitCannulaBladder boxPumpOxygenatorBridgeMonitoringHemofilter

ECLS: World Outcomes (12/04)ELSO Registry Univ. of Michigan

n (%survive to D/C) n (%survive to D/C)Neonatal Respiratory 18,703 (77%) 690 (85%)Cardiac 2,246 (39%) 122 (44%)

PediatricRespiratory 2,640 (56%) 183 (75%)Cardiac 3,073 (42%) 132 (42%)

AdultRespiratory 933 (53%) 255 (52%)Cardiac 568 (35%) 141 (38%)

Total 28,163 (67%) 1,520 (67%)

Cardio-pulmonary Bypass

Describing Ventricular Assist Devices

Extra/para-coporealIABPTandem HeartECMOAbiomedThoratecBerlin Heart

IntracoporealHeartmateNovacorJarvik 2000DeBakey Micromed

Ventricular Assist typeRightLeftBiventricular

Flow TypePulsatileNon-pulsatile

Drive TrainPneumaticElectricMagnetic

Tandem Heart

Abiomed Impella Recover

4.5 liter flow7 day use9Fr cannula

Hemodynamic effects from ImpellaImpella

Extra/Paracoporeal SupportThoratec Vad systemParacorporeal7 liter blood flowBSA > 0.7Full anticoagulation

Biventricular Support: AbiomedBVS 5000

Extracorporeal;LVAD, RVAD, BiVad.Sized for BSA >15 Liter blood flow

RVAD<LVAD flow; avoid edemaIntermediate-term supportFull anticoagulationThermodilution, mixed venous saturations not accurate.Height adjustment to balance R & L flows.Clotting at low flow

(<2 liters/min)>6000 patients supported

>65% post cardiotomy

Abiomed BVS5000 Setup

Abiomed AB5000 VentricleParacorporeal, Biventricular support

Same cannula as BVS5000

6 liter blood flow

21 day average support

>300 day longest to date

Thoratec IVADOnly Intra-corporeal Bivad>2800 patient implantsPulsatile flow,

VAD support for arrythmia

Multicenter, RCT129 Patients end-stage Heart Fail.Ineligible for cardiac txHeartmate XVE vs Best Med Rx48% reduced risk of death

52% 1 yr survival vs 25%23% 2 yr survival vs 8%

Serious adverse events;InfectionBleedingDevice malfunction

HeartMate LVAD

Thoratec VAD

Novacor LVAD

First Generation LVADFirst Generation LVAD

Thoratec Heartmate I

Heartmate IP

Heartmate XVE

HeartMate I XVE Intra-coporeal LVAD only

6-?10 liter blood flow

Textured surfaces in blood chamber creates ‘neo-intima

ASA only

Three modes;

Fixed

Auto

External (synchronous)

Portable power pack allows ambulation

Pushplate pump mechanism

Novacor LVASIntra-corporeal

6-8 liter flow

Long duration

? Best destination therapy device

Full anticoagulation

Advances in LVADsSmaller sizesSmaller sizes

Increased durability/durationIncreased durability/duration

Thoratec IVAD

WorldHeart Novacor II

Jarvik 2000

DeBakey

Second Generation LVAD – Axial Flow Pumps

HeartMate IIHeartMate II

DeBakeyDeBakey

Jarvik 2000Jarvik 2000

Thoratec Heartmate IIIntr-coporealHigh-speed, axial flow(non-pulsatile), rotary pumpBSI<1 possible6,000 to 15,000 rpm (usual 9200 rpm)4-8 liter blood flowFixed and auto speed modes

Thoratec Heartmate II; Axial flowSmall size No hemolysisFlow= 5-10 liters/minU

Third Generation LVADThird Generation LVAD

Centrifugal flow designMagnetically-levitatedLong pump durability

HeartQuestHeartQuest

DuraHeartDuraHeartWorldHeartWorldHeart Novacor Novacor Rotary VADRotary VAD

HeartMate IIIHeartMate III

Total Artificial Hearts: Abiomed AbioCorAbioCor

First Completely self-contained total artificial heart

2 lbs.

Still in FDA review

Not eligible for natural heart transplant

Artificial Hearts; Syncardia Heart

Jarvik Heart

Intra-corporeal Biventricular support

Bridge to Transplant

7-10 liter flow

Full anticoagulation

VAD Controllers

VAD Management Issues

Hemodynamics (0-12 hrs.)Adequate LVAD filling

MAP≈70mmHg.Flow rate ≈ 3-4 l/min,Fixed rates of 75, changing to auto rate control over time. RPMs 8000-9000, Pulsatility index > 4HR 96-110, small volumes ejected,more frequently from RV

Collapsed LV interventricular septum bowingIncreased venous returnRV dilation, reduced effective RV geometry, tricuspid regurgitationRV ischemia

CVP 8-15 mmHG (prompt response to increases!)Low LVAD flow + low/nl CVP= hypovolemiaLow LVAD flow + high CVP= RV overload/failure, PHTN

CVP >20 associated w/ ↓ GFR, diuretic unresponsiveness, ARF.CVVH to remove extra volume if diuretic resistant

Complications:HypotensionLVAD

Low intravascular volume, obstructed LV filling, Aortic emptyingBecause of non-occlusive system; require high enough pump speeds to avoid avoid pressure differentials below expected Ao pressures (avoid regurgitant flow)regurgitant flow)Rotary pumps can generate large negative pressure at inlet Obstruction of inlet/outlet cannulae, inadequate filling conditions

RV failureFluid overload, excessive LVAD flow, ↑ PVR, excessive systemic vasopressors, vasopressors, acid-base

Systemic VasodilationSIRSMilrinone, dobutamine

Hemorrhage {remember abdominal}, tamponadeObstructive shock; tamponade, auto-peepSepsis, anaphylaxis, adrenal insufficiency

Managing Hypotension-cont’dNormal RV + low or nl SVR

Fluids to maintain CVP 10mmHg↓ milrinone to .125 mcg/kg or turn off if LVAD flow flow are > 4l/minIncrease Nor-epi, vasopressinIncrease LVAD flow

Poor RV fxn +nl SVRMaintain Nitric Oxide 5 to 20 ppmMilrinone 0.5 mcg/kg/minDobutamine 8-10 mcg/kg/min ± Epi, Dopamine, IsuprelIsuprel

Avoiding Right Heart FailurePre-opInotropic support

PA-Catheter, EchoMilrinone, Vassopressin, Dobutamine, Nor-epi

Improve R heart volume overloadDiureticsCVVH

Correct Coagulopathy {vitamin-k,Intra-op

Same inotropic supportAprotininNitric Oxide

Post-operativeWarmCorrection of acidosis, Mild respiratory alkalosisFast RV heart Rate, A-V pacingAggressive correction of volume overload, increasing CVP

Effects of nonpulsatile blood flowBenefits of pulsatile flow;

Reduces critical capillary closing pressureImproves lymphatic flowImproves tissue perfusion; enhances diffusion of oxygen and other substrates

Adverse effects of nonpulsatile flowNeuroendocrine responses from lack of baroreceptor, renal and endothelial stimulation;

VasoconstrictionIncreased oxygen consumptionAcidosisEdema formation

Renal Effects;Increased renin, angiotensin II, AldosteroneReduced cortical and medullary blood flow

Decreased gastric mucosal pHiWienstein et al. ATS, ’79

Hamulu, Perfusion, ‘98

Shock

Acidosis

Oliguria

↑Epinephrine

Yes

+/-

No

50 60 8090100110120

Flow cc/Kg

Non-Pulsatile

Pulsatile

Effects on Systemic Perfusion with Pulsatile and Non-Pulsatile Blood Flow

Bartlett, ELSO,2000

Tominaga, JTCS,94

Golding, ASAIO,82

Bernstein, TransASAIO,74

4000cc/80kg= 50cc/kg/min

70

RecentPost-operative anticogaulation/antiplatelet therapyAntiplatelet Agents;

plts≥50,000, CT drainage <30 to 50ml/hr x 4 hours

ASA 81-325mg/d; POD 1-3, Dipyridamole (Persantine) 75mg tid; POD1-2Pentoxifylline (Trental) 400mg tid; POD 1-2

AnticoagulantsHeparin 2-5 U/kg/hr; POD 1-3, no bolusWarfarin 2mg hs; POD 5 to 7; nl hepatic/renal fxn

Other Post-operative issuesTurn on AICD if presentOut of bed, incentive spirometry Nutrition; early enteral feed (may require require feeding tube)Plasma free hemoglobin (3-10 mg/dl)

Weaning from VADs

As flow is decreased, native ejections should become more prminent on arterial waveform.

VAD Comparison ChartVAD

ABS5000

The End

Cannulation

Oxygenators & CO2 Sweep

ECMO circuit pump and controller

Cardiac Output and Mixed venous monitor

Cardio-pulmonary Bypass

Abiomed AB5000

Abiomed BVS clinical pearls