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