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.