VADs, ECMO Flashcards
Intermacs 1
Critical cardiogenic shock.
Likely req ECMO
Not expected to survive without txp or VAD
LVAD
A surgically implanted, mechanical pump that is attached to the failing left ventricle.
It works with the heart to help it pump more blood with less work.
Takes blood from LV and moves it to the aorta (via the outflow graft), which then delivers oxygen-rich blood throughout the body.
It moves blood continuously at a set speed (rpm). Continuous flow = aorta closed at rest = unable to palpate pulse, lack of pulsatility on art line
It uses external equipment for control and power operation. Drivelines (no blood) = series of wires that connects pump to external system
Indications
-Destination therapy (majority of pt)
-Bridge to transplant
-Bridge to decision
-Bridge to recovery
Intermacs 2
Inotrope dependent with continuing deterioration
May req Impella
Intermacs 3
Clinically stable w/ inotropes.
Frequent hospital admissions
Intermacs 4
Recurrent decompensation
Intermacs 5
Ok at rest but exercise intolerance
Intermacs 6
Fatigue even with mild activity
Intermacs 7
Clinically stable w/ reasonable activity. History of decompensation
VAD Medicaid Requirements
Failed Optimal Medical Management for 45/60 days
OR
IABP (Impella, balloon pumo) x 7 days
OR
IV inotropes x 14 days
EF <25%
VO2 </= 14
NYHA IIIb/IV
HMII
2nd generation (1990s-present)
Axial flow–blood pushed forward by impeller
Continuous flow
Smaller design
Speed: 8600-10000
Flow: 3-6
PI 3-7
Power 3-7
HM3
3rd generation
Centrifugal flow
Continuous flow
Intrapericardial
Speed: 4800-6200
Flow 3-6
PI 2-6
Power 3-6
Has artificial pulse which cannot be turned off
Designed to wash pump
Every 2 seconds: drops speed (2000 RPM drop), ramps it up (2000 RPM rise), goes back to baseline. <1% thrombosis rate
Heartware (HVAD)
3rd generation
Centrifugal flow
Continuous flow
Intrapericardial
Speed: 2400-3200
Flow: 3-6
PI >2
Power 3-7
Has Lavare cycle (can be turned off)-designed to wash LV and pump
–2 sec 200 RPM drop and 1 sec 200 RPM rise
–Repeats every minute
Speed
Rotating speed of the pump – set by clinician – varies by device based on pump design
Rotations per minute that propeller spins at
Flow
Calculated value, reflects cardiac output.
Know patient’s baseline.
Flow is a function of the differential pressures across the pump
Changes in flow correspond to physiologic changes in pressure
Pulsatility Index (Flow pulsatility)
Reflection of LV filling pressures. Difference between systole and diastole
Result of changes between peak flow and trough.
Know patient’s baseline
MAP Goals 70-85
Power (w)
Power required to keep pump rotating.
Direct measurement.
Direct relationship w/ flow (increased power = increased flow)
Direct relationship w/ speed (increased power = increased speed)
INdirect relationship w/ blood viscosity (increased viscosity requires more flow to run at same speed)
–Correct HCT
Pump head-flow (HQ) curves
Dictate how much flow is impacted by preload and afterload
H = Differential Pressure (afterload – preload)
Q = Flow
The shape of the HQ curves is different for every pump design; these differences determine the pump’s behavior
For any continuous flow pump (axial, centrifugal, or mixed), volume of flow through the pump is :
1. Directly related to the pressure across the pump (difference between aortic and left ventricular pressure (AOP-LVP))
2. Inversely related to the resistance (SVR)
Suction events
LV cavity collapses and forces the apical inflow cannula against the septum
Occurs from sudden decrease in LV preload:
-Hypovolemia: Over-diuresis/ Bleeding/ Decreased volume intake
-RV failure
-Tamponade
-Arrhythmia
Treatment: Treat reason for suction event
-Treat arrhythmia if present
-IV fluid
-Decrease pump speed (briefly) to open up flow
-Echocardiography to assess
Blood pressure
IF palpable pulse present –> treat Doppler as Systolic. Goal SBP <90
IF no palpable pulse present –> Treat Doppler as MAP. Goal MAP <85
Poorly controlled HTN = stroke, pump thrombosis, and right heart failure
BP Management
S/Sx Adequate Perfusion
–Warm, pink, cap refill
–Appropriate urine output
–Normalization of renal and liver panels
–Resolution of heart failure symptoms
Decompressed LV
–Decreased LV end diastolic dimensions compared to baseline
–Improvement in MR
–AV closed
Resolution of pulmonary edema on CXR
Flow is a rough estimate of CO in a patient fully supported by VAD
–CI >2.2
CVP 8-12 (10-15 post-operatively
PCWP 12-15
Anticoagulation
Artificial surfaces and supra-physiologic shear stress make anticoagulation and antiplatelet therapy required.
Heparin as a bridge to therapeutic INR (goal 2-3 for chronic therapy) **Now only HMII and HVAD
Initiate once coagulation parameters are within acceptable range and/or CT drainage declines (usually 12 to 24 hours post implant)
Standard aPTT goal 60-85 beyond POD8
Bolus only in cases of suspected thrombus and confirmed with heart failure attending
Vitamin K reserved for life-threatening bleeding – use caution
ASA by device (81 mg daily HM3, 162 mg daily HVAD)
ECHO
MR
–In absence of mitral pathology, MR should decrease after LVAD
LV
–Decrease in LVEDD (HMII > HM3, HVAD)
–Dependent on myocardial compliance
Septum
–Positioning should be midline. Shifting indicates high pressures
Inflow/outflow cannula velocities
–Velocity changes indicate changes in flow pathways
AV
–New/frequent opening warrants workup: recovery, sepsis, high afterload, vol overload
–De novo AI is complication of mechanical circulatory support
RV dysfunction
–RV preservation critical
–Reduce PVR, tx pulm HTN
Position of inflow cannula
–Directed at mitral valve
Prevention of RV failure
Most VAD patients have moderate RV dysfunction preoperatively
RV geometry may be altered when LV is
decompressed
Findings: decreased PI, increased CVP, decreased MAP, decreased PCWP, dilation of RV
AFTERLOAD
-NO
-Proper device settings
-Vent settings: low PEEP, low I/E ratio, PaO2, pH
-Warm pt
-Minimize transfusions
PRELOAD
-Address tricuspid insufficiency
-Avoid/control bleeding
CONTRACTILITY
-Early inotropic support
-Proper weaning from CPB
-Balance septum
-Tx arrhythmias
Pump thrombosis
Pump behavior dependent upon location of thrombus
–Increases in power = impeller thrombus (∆ efficiency)
–Decreases in power = inflow or outflow
Presentation:
Evidence of hemolysis:
LDH 2.5 x baseline , Elevated pfHgb >40, Decreased haptoglobin,
UA + protein, RBC, bilirubin, urobilinogen (tea colored urine)
Increase in Cr and LFTs
Echo - Dilation of LV, new AV opening, worsening MR
Return of HF symptoms
Ability to palpate pulses, increase in pulse pressure (>30 mmHG)
CVA or embolic event
Ventricular arrythmias
MNGMT–
Inflow cannula
Acute inflow obstruction typically requires surgical intervention
Decommission VAD, and support medically if able
Urgent transplant if candidate
Impeller
Thrombolytics (consider with HVAD, not beneficial in HMII)
Pump exchange (Always required for HMII if surgical candidate)
Outflow graft
Typically a gradual progression
Pump exchange
Decommission VAD, and support medically if able
Urgent transplant if candidate
Low flow alarm
Something inhibits flow through the VAD
HMII/HM3–pre-set at 2.5 LPM
HVAD–set by clinician
DDX–patient problem
Hypovolemia
Tamponade
Bleeding
RVF
Pulm HTN
Arrhythmia
HTN
DDX-pump problem
Inflow cannula obstruction
Outflow cannula obstruction
Sweep
Minute ventilation
Total amount of gas pushed through oxygenator in one minute
Increased or decreased based on CO2
Flow (ECMO)
=cardiac output
Amount of blood through the circuit.
Titrate by increasing RPMs
ECMO flow 1.8-2.4 or greater
High flow indications: little/no native cardiac functioning, myocardial stunning, rest the heart
Low flow indications: easier to maintain, less blood trauma, can diurese while maintaining adequate preload, allows for return of pulsatility
LV distention
ECMO (especially high flow) can inhibit LV ejection and lead to LA/LV overfilling
Indicators:
Low pulsatility, low EF%
Ao insufficiency w/ retrograde flow into LV
AV not moving
Sequela:
Clot formation
Fluid overload, CXR changes
Poor oxygenation
EC-Pella: Vent LV and good ECMO weaning measure
