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1 > VADs, ECMO > Flashcards

VADs, ECMO Flashcards

1
Q

Intermacs 1

A

Critical cardiogenic shock.
Likely req ECMO
Not expected to survive without txp or VAD

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1
Q

LVAD

A

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

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2
Q

Intermacs 2

A

Inotrope dependent with continuing deterioration
May req Impella

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3
Q

Intermacs 3

A

Clinically stable w/ inotropes.
Frequent hospital admissions

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4
Q

Intermacs 4

A

Recurrent decompensation

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5
Q

Intermacs 5

A

Ok at rest but exercise intolerance

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6
Q

Intermacs 6

A

Fatigue even with mild activity

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7
Q

Intermacs 7

A

Clinically stable w/ reasonable activity. History of decompensation

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8
Q

VAD Medicaid Requirements

A

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

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9
Q

HMII

A

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

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10
Q

HM3

A

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

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11
Q

Heartware (HVAD)

A

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

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12
Q

Speed

A

Rotating speed of the pump – set by clinician – varies by device based on pump design

Rotations per minute that propeller spins at

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13
Q

Flow

A

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

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14
Q

Pulsatility Index (Flow pulsatility)

A

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

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15
Q

Power (w)

A

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

16
Q

Pump head-flow (HQ) curves

A

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)

17
Q

Suction events

A

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

18
Q

Blood pressure

A

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

19
Q

BP Management

A

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

20
Q

Anticoagulation

A

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)

21
Q

ECHO

A

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

22
Q

Prevention of RV failure

A

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

23
Q

Pump thrombosis

A

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

24
Q

Low flow alarm

A

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

25
Q

Sweep

A

Minute ventilation
Total amount of gas pushed through oxygenator in one minute

Increased or decreased based on CO2

26
Q

Flow (ECMO)

A

=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

27
Q

LV distention

A

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

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