For general principles of timing of ECMO and patient selection see the following links
The likelihood of a patient receiving benefit from the application of VA ECMO for cardiogenic shock depends on: age, diagnostic category/cause of acute heart failure, severity of shock prior to commencement and associated chronic organ failures (non-cardiac comorbidities).
Essential considerations regarding the clinical application of VA ECMO in adult populations
- VA ECMO provides minimal patient benefit if commenced after established multi-organ failure and peripheral ischaemia. Only younger patients without comorbidities will benefit from support initiated after the onset of severe secondary organ failures.
- Likelihood of irreversible heart failure must be considered in all patients with severe circulatory failure. Patients with known chronic heart failure or massive cardiac injury with high potential for irrecoverable heart failure beyond short term mechanical support such as VA ECMO, that are not suitable for transplantation, should not commence short term support.
- VA ECMO may have a role in the prevention of shock and secondary organ injury in high risk cardiac interventions. Many patients may potentially benefit from competently applied VA ECMO in this context.
- VA ECMO presents significant modifiable risks to patients and high healthcare care resource utilization and must be administered only by trained, credentialed and fully equipped staff
In order to assist with assessing patient eligibility, a chart has been provided to graphically represent the interaction of patient and disease factors.
Additional information is presented separately
Steps to use chart
- Determine diagnostic group (score 1, 2 or 3)
- Determine presence of modifying acute (score +1) and chronic illness (score +1)
- Calculate combined score (1-5)
- Make sure there are no absolute contraindications
- Use chart to observe eligibility and expected benefit from ECMO
Once established that the patient is eligible for VA ECMO, proceed to the next section on clinical triggers for more details on the timing of initiation of VA ECMO. Eligibility and timing should be discussed with the senior ECMO clinician on call 24/7.
Diagnoses are ordered according to commonly associated outcomes with VA ECMO into ‘Favourable’, ‘High Risk’ and ‘Unfavourable’ pathologies. These are related to the reversibility and treatability of the condition. Chronic cardiac failure is assessed separately in the next section.
Favourable Diagnostic Categories (Score =1)
- Fulminant myocarditis
- Pulmonary embolism with cardiogenic shock
- First presentation cardiomyopathy
- Primary arrhythmogenic cardiomyopathy
- Drug overdose with cardiac depression and no anticipated long term sequelae
- Primary graft dysfunction post heart transplant (see separate chart for trigger)
- Ischaemic VSD post AMI
High Risk Diagnostic Categories (Score =2)
- AMI complicated by cardiogenic shock – early reperfusion
- Papillary muscle rupture/ mitral regurgitation with AMI
- Failure to wean off cardiopulmonary bypass
- Heart transplant recipient with acute rejection suitable for VAD/ re-transplant
Unfavourable Diagnostic Categories (Score =3)
- AMI complicated by cardiogenic shock – delayed or failed reperfusion
- Heart transplant recipient with chronic rejection suitable for VAD/ re-transplant
- Chronic cardiomyopathy not suitable for bridge to VAD (sepsis and/or renal failure)
- HOCM associated heart failure
- Restrictive chronic cardiomyopathy
- Adult septic shock
Note: ECPR, bridge to transplant and periprocedural diagnostic groups are not included here.
The comorbidities of the patient and the acute clinical state of the patient are modifiers of the patient outcome and taken into consideration here.
Increase score by one for the presence of chronic or acute modifiers. If both acute and chronic modifiers are present increase score by two.
Chronic (comorbidities) – one or more present add one to score (Score +1)
- Peripheral vascular disease (symptomatic, revascularised or amputation)
- Previously known ischaemic heart disease or prior revascularisation
- Prior valve surgery, CABG or aortic surgery
- Moderate COPD (GOLD Stage II, FEV1 50-80%)
- Chronic renal failure stage 3 or 4 CKD (eGFR 60-15)
- Chronic liver disease
- Long-term immunosuppression
Acute clinical condition – one or more present add one to score (Score +1)
- Lactate ≥10
- Ischaemic hepatitis defined by AST or ALT >1000, or, INR >3.0
- Anuria >4 hours
- Age >75
- Terminal illness or non-treatable malignancy
- Liver cirrhosis Child-Pugh B or C
- Irreversible CNS injury
- Chronic renal failure CKD 5 or dialysis
- End-stage COPD
- Chronic symptomatic cardiac failure (NYHA 3 or 4) and not a VAD/transplant candidate
- ECMO initiation would not be in keeping with known patient wishes or that of the patient’s medical treatment decision maker (MTDM)
- Inability to cannulate safely due to vascular pathology (e.g. multiple stenosed or thrombosed vessels such as IVC Syndrome)
- Aortic regurgitation is an important modifier for patient selection. Where severe cardiac failure precedes VA ECMO initiation and there is a high likelihood of minimal LV ejection (or non-ejection) following VA ECMO initiation, the presence of aortic regurgitation should preclude VA ECMO due to the high risk of pump driven LV distention. VA ECMO should only be applied in the presence of known aortic regurgitation where there is a reasonable expectation that LV ejection will be maintained or valvular dysfunction can be corrected surgically in a timely manner.
- Cardiogenic shock with advanced microcirculatory failure with severe mottling or established peripheral purpura
- Cerebral deficit with fixed dilated pupils
Clinical trigger and timing of VA ECMO
VA ECMO is considered for patients in cardiogenic shock with a cardiac index and blood pressure that are refractory to less invasive support. A guide to the limits of standard support are given below. I.e. benefits from further escalation of inotropes is unlikely to provide additional patient benefit
- Moderate or high dose inotropes (adrenaline > 0.2μg/Kg/min equivalent) in combination with vasopressors and positive pressure ventilation (+/- IABP) for predominantly left ventricular failure
- Moderate or high dose inotropes (adrenaline > 0.2μg/Kg/min equivalent) in combination with pulmonary artery vasodilator and/or vasopressors for predominantly right ventricular failure
Unsafe cardiac output, blood pressure, progression of secondary organ failures or rising lactate (> 5 mmol/L) despite ICU supports may indicate failure of non-mechanical circulatory support.
It is important to stress that VA ECMO may be commenced at lower thresholds and referral for ECMO can occur even before inotropes are required
The following additional clinical and logistic factors must also be considered when determining the need for, and the timing of, ECMO
- Rate of cardiac failure progression – Rapidly progressive (4-6 hours) hypotension, with very severe echocardiographic features of cardiogenic shock particularly in the early stages of hospital admission, are often associated with a fulminant illness that reduces the time window when ECMO may be of benefit
- Onset of secondary organ failures, or need for high dose vasoactive support secondary to respiratory failure, may support earlier ECMO commencement. Note the onset of hepatic or skin ischaemia tend to be late signs that may be indicative of a pre-terminal state
- The need for inter-hospital patient transportation. ECMO is currently considered the safest mode of transport for unstable patients with severe cardiac failure requiring inter-hospital transport
Bridge to VAD or cardiac transplantation
Utilising ECMO as a bridge to VAD support or cardiac transplantation is suitable for patients that have been worked up and are suitable for VAD and is initiated in conjunction with the Chronic Heart Failure Unit.
Where patients present in decompensated heart failure without prior workup (and without clear contraindications to ECMO) VA ECMO may be offered with the aim of providing physiological stability to allow time for assessment for potential reversibility and suitability for long term mechanical support. See patient eligibility above.
Acute decompensated heart failure in a patient with chronic heart failure selected for transplantation short term mechanical cardiac support (with or without early LV decompression) is indicated as a bridge to VAD. Emergent durable LVAD implantation should not proceed in the setting of acute decompensated heart failure. VA ECMO provides haemodynamic stabilisation and time for secondary organ recovery before the VAD procedure. Outcomes are inferior utilising VAD as the first option in this patient group.
Known Chronic Heart Failure selection pathway
Severe, irreversible heart failure
Heart failure unit approval in principle for transplant (PRIOR to ECMO)
Cardiac Surgical Consultant approval for transplant (PRIOR to ECMO)
ICU team approval
Absolute contraindications to ECMO in patients with known chronic heart failure
- Prolonged cardiac Arrest
- Multiple system organ failure*
- Inadequate vascular access**
*End stage cardiac failure patients referred for ICU support in extremis or shock, should not receive ECMO as a bridge to recovery or decision due to the extremely low likelihood of achieving acceptable long term outcomes and the need for prolonged support and adverse effects.
**Patients with peripheral vascular disease must have a vascular ultrasound (+/- CT angiogram) prior to ECMO cannulation to exclude significant arterial stenosis.