Veno-Arterial ECMO

What is VA ECMO?

VA ECMO supports the heart and lungs by

decreasing the workload of the organs to

allow for recovery

VA ECMO drains blood from the venous

system, circulates it through the ECMO

circuit, passes it through an artificial lung

where oxygen is given and CO2 is

cleared, and returns it to the arterial

system.

VA ECMO Support Goals

Allow for cardiac recovery by offloading

the work of the ventricle

Increase perfusion to vital organs by

increasing blood flow and oxygenation

Decrease the need for high dose

inotropes and pressors

The physiologic goal is to

improve oxygen delivery to

the tissues

Oxygen Delivery/Consumption

DO2 – the rate of oxygen delivered to tissue

during metabolic demand

CaO2 - The oxygen content in arterial blood

DO2 = CO x CaO2x10

Normal adult: 600cc/min/m2

Oxygen Delivery – D02

The amount of oxygen delivered to the

tissues each minute

Can be affected by

Cardiac output

Hemoglobin

Normal D02:V02 ratio is 5:1

600cc/min/m2:120cc/min/m2

Oxygen Delivery/Consumption

VO2 – Maximal oxygen consumption that

an individual can utilize

VO2 – 120cc/min/m2

VO2 increases with exercise,

catecholamine release or

administration, and sepsis

DO2 is controlled by homeostatic mechanisms to be 5x VO2

20% of available O2 is used for metabolism

80% left in venous blood

When DO2/VO2 ratio falls below 2:1, there

is not enough O2 to maintain aerobic

metabolism

Switches to anaerobic process→lactic

acidosis rather than CO2

Leads to supply/demand hypoxia

resulting in lactic acidosis and organ

failure

ECMO is used when DO2:VO2 is less than

2:1 and/or the mechanisms used to

maintain a 2:1 ratio are damaging

High dose vasopressors

High airway pressures

The BIG Concept of ECMO

Drain deoxygenated venous blood

Remove CO2

Add oxygen

Return to oxygenated blood to

systemic circulation by via arterial

circulation

Indications for VA ECMO

Refractory Cardiogenic Shock (RCS)

RCS is defined as:

Persistent hypotension with SBP<90mmHg

CI <2.0 with evidence of end organ hypoperfusion leading to multisystem organ failure despite pharmocologic intervention

Cold extremities (high SVR)

VA ECMO should be instituted within 60 min of RCS

Indications for VA ECMO Acute Myocardial Infarction

ECPR of arresting patient

Post-partum cardiomyopathy

Post-cardiotomy

Primary Graft Dysfunction post heart transplant

Acute Myocarditis

Acute Pulmonary Embolism

Acute decompensated chronic heart

failure/cardiomyopathy

Pre-operative support

Support during high risk PCI

Acute Myocardial Infarction

6-10% STEMI pts suffer from refractory

cardiogenic shock

Mortality is 40-80%

If RCS is apparent despite the use of

pharmacology, and evidence of multisystem

organ failure – then VA ECMO should be

instituted ASAP

VA ECMO can support heart and lung function,

while providing perfusion to the rest of the body

Most common configuration of support for the acute MI or arrest patient is the femoral

approach with venous drain cannula in the femoral vein, and arterial return in

the femoral artery.

Postcardiotomy

The need for ECMO implantation during or

following cardiac surgery occurs in

approximately 0.5%-2.6% of patients.

Common scenario is inability to wean from

cardiopulmonary bypass

Refractory cardiogenic shock post surgery

Cardiac arrest

Acute graft dysfunction/failure after transplant

Access for cannulation during surgery is central

cannulation - taking advantage of the CPB

cannula already placed

Provides better left ventricle decompression

Improves coronary and upper body oxygenation

Acute Myocarditis

Acute myocarditis can be a rather benign course with

rapid cardiac recovery.

Or it can occur rapidly with refractory cardiogenic shock

and ultimate death if MCS is not instituted.

Biventricular failure

Acute Myocarditis

VA ECMO is beneficial in Acute

Myocarditis with RCS

Immediate biventricular support

Respiratory support

Increased peripheral perfusion

Recovery can occur in 7-10 days

Acute Pulmonary Embolus

Overall mortality up to 15%

Acute RV failure and cardiogenic shock

can result in early death

Respiratory status is compromised due to

ventilation/perfusion mismatch and

subsequent hypoxia and hypercapnia

Acute Pulmonary Embolus

VA ECMO provides unloading of the acutely overloaded

RA/RV – thus increasing CO by decreasing the the septal

shift and allowing better LV diastolic filling

VA ECMO relieves hypoxemia thus adequately perfusing

organs

VA ECMO can provide stability, allowing for definitive

treatment

Thrombolytic therapy

Surgical embolectomy

ELSO Registry reports 56% survival to discharge for PE

pts supported by ECMO

End stage heart failure

Bridge to LVAD

Bridge to Transplant

Bridge to Decision

Extracorporeal Cardio-Pulmonary

Resuscitation (ECPR)

Restores circulation when used in

conjunction with ACLS.

Data show improved in-hospital survival

Up to two years free of major neurologic

impairment when VA ECMO is used in

conjunction with CPR

Contraindications for VA ECMO

RELATIVE Contraindications

Unrecoverable cardiac function/non-reversible

etiology AND/OR

Patients who are not candidates for transplant

or durable VAD (“No Way Out”)

Chronic organ dysfunction (emphysema,

cirrhosis, renal failure)

Unwitnessed cardiac arrest with >60min to ROSC

Unrepaired Ao Dissection or AI

Compliance limitations

Financial/Social limitations

Contraindications

High risk of systemic bleeding/ not an a/c

candidate

Recent or expanding hemorrhagic CVA

Terminal malignancy

Non-recoverable cardiac, pulmonary, or

neurologic disease

When you get the ECMO call…

SAVE Score

Survival After VA ECMO

Diagnosis (Myocarditis, Refractory VT/VF, Post heart or lung txplt, Congenital heart disease, Other)

Age (18-38, 39-52, 53-62, >63)

Weight (<65kg, 65-89kg, >90kg)

Cardiac

Pulse pressure pre ECMO <20mmHg

Diastolic BP pre ECMO >40mmHg

Pre ECMO cardiac arrest

Respiratory

Peak inspiratory pressure <20cmH20

Intubation duration pre ECMO (<10hrs, 11-29hrs, >30hrs)

Renal

Acute renal failure

Chronic renal failure

Hc03 pre ECMO <15mmol/L

Other organ failures pre ECMO

CNS dysfunction

Liver failure

SAVE Score

Predicted Survival

Class I: SAVE Score >/= 5 →75%

Class II: SAVE Score 1-5→58%

Class III: SAVE Score -4-0→ 42%

Class IV: SAVE Score -9- -5→ 30%

Class V: SAVE Score </= -10 →18%

Cannula Positions

Peripheral Cannulation

Femoral artery

Femoral vein

Distal perfusion catheter

LV vent

Fast and Easy

Patients can be rapidly cannulated

at bedside

Patients can be cannulated without

need to go to the OR

Can be done by Surgeons,

Interventional Cardiologist,

Intensivists, etc.

Peripheral Limitations

Can be limited by peripheral

vascular disease

Can be limited by body habitus

Risk of limb ischemia

Femoral vein and artery

cannulation performed

percutaneously or direct

cutdown on the vessel

Venous cannula tip is aimed

at the mid Right Atrium or

RA/SVC junction

Arterial cannula lies in the iliac

artery

Distal Perfusion Catheter

Leg ischemia is a major concern with peripheral

cannulation

A distal perfusion catheter should be put in for

all femoral arterial cannulations

A 6-8fr cannula is placed in the superficial

femoral artery

Spliced into arterial perfusion limb of ECMO

circuit

Establishes adequate perfusion of the distal leg

LV Vent

Peripheral VA ECMO does not unload the LV

Can actually increase LV afterload

Main cause of pulmonary edema while on ECMO

Stagnant blood in the LV can form clot and can lead to

complete thrombosis of the LA/LV

Can vent with:

IABP

Impella device

LV drain

Harlequin

(“North/South”)

Syndrome

• Occurs when oxygen poor blood is ejected from the heart and mixes oxygen rich blood flow from the ECMO circuit.

• Increased risk of oxygen poor blood ”perfusing” the coronary arteries and aortic arch.

• Pulse oximetry on the right hand and arterial blood gases drawn from the right radial artery indicate the estimated oxygenated blood delivered to the cerebral circulation from the femoral artery/ECMO circuit

Treatment

Adjustment of mechanical ventilator

Decreasing native cardiac output by

decreasing inotropes

Increase ECMO flows

Add additional venous return cannula

(V-AV)

Central Cannulation• Usually RA to Ao

• Need OR to

perform sternotomy

• Not limited by PVD

or body habitus

• No risk of limb

ischemia

• Less likely to cause

differential hypoxia

(Harlequin

Syndrome)

RV Support (RECMO)

Right Atrium (drain)

Pulmonary Artery (return)

LV Support

Left Ventricle (drain)

Aorta (return)

Maintenance

Maintenance

Monitor organ and limb perfusion

Give time for improvement

Maintain pulsatility

Adjust blood flow to maintain

MAP>65mmHg

SV02 >65%

Lactate clearance

RUE SP02 >90%

Improvement

Reduce vasoactive medications

Lowest Inotrope possible

Lowest vasopressor possible

Wean vent settings

Wean sedation

Importance of LV Ejection/Pulsatility

Decreases LV distention

Prevents LV and Aortic root clot

Monitor for differential hypoxia

How to Improve Pulsatility/Decrease

Distention

Reduce ECMO flow

Increase Inotropic Therapy

LV Decompression

IABP

Impella

LV vent

Weaning of ECMO

When to Consider Weaning

Able to maintain MAP >65mmHg

Good pulsatility on arterial line and PA line

Low dose inotropes, and ideally off

vasopressors

Complication requiring urgent

decannulation

Weaning Trial

Decrease ECMO flows 0.5LPM q5-10min

Echo guidance to evaluate for distention

Increase in RV preload and decrease in LV

afterload will assess if myocardial recovery has

occurred to the point that the patient will

tolerate decannulation

Weaning Success

MAP 70-80

CVP <12

RV contractility, size, degree of TR

CO/CI sustainable with LVEF >40%

Can titrate inotropes to

accommodate

Weaning Strategies

Weaning success is removal of VA ECMO

without further need for mechanical

support due to cardiac failure in the

following 30 days.

Patients with myocardial recovery should

be weaned

Patients with end stage dilated

cardiomyopathy should be bridged to

LVAD or transplant

Weaning Failure

Need a plan

Re-cannulate

Transition to durable support

Palliation

Weaning Strategies

If pulmonary function is severely impaired

(P/F ratio <100mmHg), then transition to

VV ECMO should be considered.