Understanding the Impella ella ella eh eh eh…… Part II!

Author: Dr Sean Keane
Peer reviewers: Dr Vinodh Nanjayya, A/Prof Chris Nickson

Everything ECMO 035

A 58-year-old female with an acute myocardial infarction (AMI) has a successful percutaneous cardiac intervention (PCI) to a proximal left anterior descending (LAD) lesion in the cath lab. Post procedure she is in cardiogenic shock. The bedside echo shows a severely impaired left ventricle (LV) with preserved right ventricular (RV) contractility and no major valvular pathology. The hospital is out of extracorporeal membrane oxygenation (ECMO consoles) due to the COVID-19 crisis, and the conversation shifts to inserting an Impella®.

Part 2 discusses contraindications, anticoagulation management, complications and evidence. In Part 1 we discussed principles, indications, insertion and positioning of an Impella®.

Q7. When might I not use an Impella®?

Left-Sided DevicesRight-Sided Devices
Mural thrombus in the LVPulmonary artery wall conditions that would preclude placement or positioning of the Impella RP® device
Mechanical aortic valveMechanical tricuspid or pulmonic valve
Constrictive heart diseaseSevere tricuspid or pulmonic valve stenosis
Aortic valve stenosis/calcification equivalent to an orifice area ≤0.6cm2Severe tricuspid of pulmonic valve regurgitation
Moderate to severe aortic insufficiencyMural thrombus of the right atrium or vena cava
Severe peripheral vascular disease precluding placement of an Impella® systemPresence of a vena cava filter or caval interruption device, unless there is clear access from femoral vein to right atrium large enough to accommodate a 22F Fr catheter
Significant heart failure in the setting of cardiogenic shockAnatomic condition preventing pump insertion
Combined cardio-respiratory failure 
Atrial or ventricular septal defect 
Left ventricular rupture 
Cardiac tamponade 
Table 3. Contraindications to Impella® insertion (from Abiomed website)

Q8. Does this patient require anticoagulation after Impella® insertion?

Yes, patients require systemic anticoagulation. Target an aPTT 60-80, anti-Xa 0.3-0.5 or ACT 160-180 seconds from time of device insertion to explant.

Unfractionated heparin is most commonly used, and is administered via:

  1. Purge solution (5% dextrose w 50 IU/ml heparin) via a flush line to lubricate the micro-axial motor and maintain a pressure of 300-1100mmHg within the device to prevent blood entering the Impella® motor
  2. Additional intravenous heparin may be needed if anticoagulation is subtherapeutic with purge solution alone.

It is important to note that the AIC automatically adjusts the purge solution rate between 2-30ml/hour to achieve target purge pressure, which can markedly change the systemic heparin dose. If aPTT is in the supratherapeutic range using purge solution alone, a lower concentration of unfractionated heparin (12.5 or 25 IU/ml) can be used.

Q9. Are there any other associated complications?

Unfortunately yes.

There are a number of potential complications to consider:

  • Vascular: insertion site bleeding; haematoma; perforation; distal limb ischemia; compartment syndrome; pseudoaneurysm formation; arterio-venous fistula formation; retroperitoneal haemorrhage
  • Haemorrhagic: stroke; gastrointestinal bleeding; transfusion related complications
  • Haemolysis due to mechanical erythrocyte shearing, which may be improved by re-positioning the device.
  • Embolisation of thrombus or atherosclerotic plaque with vascular occlusion, e.g. stroke
  • Cardiac: arrhythmias; pericardial effusion; cardiac tamponade; chamber perforation
  • Infection
  • Device malposition, which can be detected by alarms on the AIC, and by clinical changes in patient haemodynamics
  • Device malfunction: failure; fracture; kinking; detachment

Q10. This patient requires ongoing mechanical circulatory support at day 4, what are my options?

Similar to VA-ECMO, an Impella® should be thought of as a bridge to:

  1. Recovery, or successful completion of high-risk PCI procedure
  2. Durable VAD as a bridge to heart transplant
  3. Transition to comfort care if no prospect of recovery and not a transplant candidate

Q11. How is the Impella® insertion site managed when the device is removed?

Femoral artery puncture sites can be managed with direct manual compression, a Perclose suture-mediated closure system, or open surgical repair. An Impella® inserted via the aorta or axillary artery at the end of cardiac surgery will require surgical closure.

Femoral vein puncture sites for Impella RP® can be managed with manual compression.

Q12. Is there any evidence to support the use of an Impella®?

Large randomised controlled trials are lacking. A number of attempted studies have failed due to poor enrollment. Completed randomised studies were not designed or powered to detect an outcome difference between an Impella® and a comparator.

Conflicting data emerges from retrospective studies. A number of retrospective studies using registry data suggest that an Impella® is associated with lower morbidity and mortality in patients with cardiogenic shock, particularly in the setting of acute myocardial infarction. Early use is associated with improved survival versus being used as salvage therapy. However, a recent meta-analysis of randomised and observational trials showed no difference between IABP and Impella® use in the risk of 30-day mortality among patients with cardiogenic shock. In addition, another recent meta-analysis suggests the introduction of Impella® devices for mechanical circulatory support has resulted in increased adverse events and costs.

Overall, large adequately powered clinical trials of Impella® are required to provide a strong evidence base to inform clinical decision making.

References

  • ABIOMED [Internet]. 2020 Aug 25; Available from: https://www.abiomed.com
  • Amin AP, Spertus JA, Curtis JP, Desai N, Masoudi FA, Bach RG, McNeely C, Al-Badarin F, House JA, Kulkarni H, Rao SV. The evolving landscape of Impella use in the United States among patients undergoing percutaneous coronary intervention with mechanical circulatory support. Circulation. 2020 Jan 28;141(4):273-84.
  • Griffith BP, Anderson MB, Samuels LE, Pae Jr WE, Naka Y, Frazier OH. The RECOVER I: a multicenter prospective study of Impella 5.0/LD for postcardiotomy circulatory support. The Journal of thoracic and cardiovascular surgery. 2013 Feb 1;145(2):548-54.
  • Khalid N, Rogers T, Shlofmitz E, Chen Y, Musallam A, Khan JM, Iantorno M, Gajanana D, Hashim H, Torguson R, Bernardo N. Adverse events and modes of failure related to Impella RP: insights from the Manufacturer and User Facility Device Experience (MAUDE) Database. Cardiovascular Revascularization Medicine. 2019 Jun 1;20(6):503-6.
  • Lauten A, Engström AE, Jung C, Empen K, Erne P, Cook S, Windecker S, Bergmann MW, Klingenberg R, Lüscher TF, Haude M. Percutaneous left-ventricular support with the Impella-2.5–assist device in acute cardiogenic shock: results of the Impella–EUROSHOCK-registry. Circulation: Heart Failure. 2013 Jan;6(1):23-30.
  • Mario I, Albani S, Giannini F, Colangelo S, Boccuzzi GG, Roberto G, Brilakis ES, de Ferrari GM, Colombo A. Short term outcomes of Impella in cardiogenic shock: A review and meta-analysis of observational studies. International Journal of Cardiology. 2020 Sep 22.
  • O’Neill WW, Grines C, Schreiber T, Moses J, Maini B, Dixon SR, Ohman EM. Analysis of outcomes for 15,259 US patients with acute myocardial infarction cardiogenic shock (AMICS) supported with the Impella device. American heart journal. 2018 Aug 1;202:33-8.
  • Ouweneel DM, Eriksen E, Sjauw KD, van Dongen IM, Hirsch A, Packer EJ, Vis MM, Wykrzykowska JJ, Koch KT, Baan J, de Winter RJ. Percutaneous mechanical circulatory support versus intra-aortic balloon pump in cardiogenic shock after acute myocardial infarction. Journal of the American College of Cardiology. 2017 Jan 16;69(3):278-87.
  • Rihal CS, Naidu SS, Givertz MM, Szeto WY, Burke JA, Kapur NK, Kern M, Garratt KN, Goldstein JA, Dimas V, Tu T. 2015 SCAI/ACC/HFSA/STS clinical expert consensus statement on the use of percutaneous mechanical circulatory support devices in cardiovascular care: endorsed by the American Heart Assocation, the Cardiological Society of India, and Sociedad Latino Americana de Cardiologia Intervencion; Affirmation of Value by the Canadian Association of Interventional Cardiology-Association Canadienne de Cardiologie d’intervention. Journal of the American College of Cardiology. 2015 May 19;65(19):e7-26.
  • Seyfarth M, Sibbing D, Bauer I, Fröhlich G, Bott-Flügel L, Byrne R, Dirschinger J, Kastrati A, Schömig A. A randomized clinical trial to evaluate the safety and efficacy of a percutaneous left ventricular assist device versus intra-aortic balloon pumping for treatment of cardiogenic shock caused by myocardial infarction. Journal of the American College of Cardiology. 2008 Nov 4;52(19):1584-8.
  • Shariff M, Doshi R, Pedreira Vaz I, Adalja D, Krishnan A, Hegde S, Kumar A. Impella versus intra-aortic balloon pump in cardiogenic shock: a meta-analysis assessing 30-days mortality. European Heart Journal. 2020 Nov;41(Supplement_2):ehaa946-1130.

All case-based scenarios on INTENSIVE are fictional. They may include realistic non-identifiable clinical data and are derived from learning points taken from clinical practice. Clinical details are not those of any particular person; they are created to add educational value to the scenarios.

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