Background

  • Developed as a bridge for cardiac transplant patients, now also being used as a temporary measure in cardiomyopathies and as a final treatment for those not qualifying for transplant
  • Shown to prolong survival in these clinical settings (months to years)
  • Can have left VAD, right VAD or both ventricles with separate pump
  • Goal is to assist heart function and augment cardiac output
  • Components:
    • Control box: displays battery power, recent alarms
    • Pump: Internal pump, taking blood from ventricle and putting into aorta
    • Driveline: connects pumps to external battery and controller (usually out of abdomen)
    • Power supply: battery packs and a power base station (at home)
  • Large console at LVAD centers: shows power, flow, speed, pulsatility
    • These are the major variables that will be set by their cardiologists

1st generation: pneumatic pump → pulsatile blood flow

(Wilson 2009)

2nd generation: centrifugal/axial flow pump → continuous flow

  • Directly connected to patients LV (lies above the diaphragm within the pericardium)
  • Blood back to ascending aorta by separate outflow cannula
  • Advantages to 1st generation:
    • Smaller size
    • Increased durability
    • Increased efficiency
    • Decreased thrombogenicity

(Aaronson 2012)

General Management

  • Contact the LVAD team immediately

Focused History

  • Type of device, placement date, previous complications (most devices have this information on it or the patient should know)

Physical exam

  • With continuous flow devices, the patient will not have a pulse!
  • Blood pressure
    • Obtain a manual cuff and arterial doppler device – find brachial or radial artery
    • Inflate manual cuff until arterial flow cant be heard, then release; MAP is recorded when arterial flow returns through doppler
    • Target MAP Is 70-80 mmHg, max of 90
      • Can also monitor with a-line in more critical situations
    • Pulse oximetry: may not be accurate if no pulsatile flow – consider obtaining ABG if concerned for respiratory issues
    • Cardiac exam: a “hum” should be heard, check for JVD or pulmonary edema (signs there may be right heart failure)
    • Power cord: from abdomen usually, evaluate for infection

Diagnostics

  • Labs: CBC, CMP, PT/PTT/INR, LDH, haptoglobin, TEG (if available), LDH, BNP, troponin, UA, T&S
  • EKG should be performed
  • CXR: To evaluate for signs of heart failure, cardiomegaly, pulmonary edema, PNA, driveline damage
  • POCUS: LV and RV function, signs of RH strain may signify pulmonary hypertension or a PE. Overdistended LV may indicate pump malfunction, thrombus or severe aortic regurgitation. Check for pericardial effusion or tamponade as well.

Complications and Management
Always consult patients LVAD team!

Bleeding:

  • Etiology:
    • Usually from supratherapeutic INR (patients are usually on coumadin, antiplatelet therapy with INR goal of 2-3)
    • AV malformations
    • Acquired von Willebrand disease from pump shear forces
  • Signs
    • GI bleeding
    • Epistaxis
    • Intracranial hemorrhage
    • Pericardial tamponade /effusion
  • Treatment
    • Reverse with FFP or PCC (for INR, treat until back to 2-3 to avoid clotting in pump)
    • DDAVP or cryoprecipitate (vWD)
    • Consider TXA
    • Platelet transfusions
    • Vitamin K

Infection

  • Etiology
    • Sepsis
    • Pump endocarditis
    • Driveline infection
  • Signs
    • Can result in low flow, hypovolemia
    • Most common cause of death (usually within 3 months of placement)
  • Treatment
    • Antibiotics (cover for MRSA)
    • Fluids as needed
    • Obtain US/CT to evaluate abscess/collection

Thrombosis

  • Can see in 2-35% of patients, suspect in any arrest or cardiogenic shock or decreased flow
  • Evaluation
    • Knocking sound on cardiac exam can be sign of rotor thrombus
    • POCUS: Overdistended LV with shift of septum indicates blockage and can possibly see hypoechoic mass near inflow cannula
    • Labs: elevated LDH, hemoglobinuria
  • Treatment
    • Anticoagulation with a continuous heparin infusion and antiplatelet therapy
    • Consider tPA in life threatening situations

Arrhythmia

  • Primary – Intrinsic to heart
    • Ventricular arrhythmias are common from scarring
    • SVT and ventricular tachycardia can be common
    • Cardiac output is from the LVAD and not the heart ∴ the patient should have no signs or symptoms if they are VAD-dependent
  • Secondary
    • Can occur if LV septum/free wall are sucked into conduit vs hypovolemia
      • Difficult to distinguish
  • Treatment:
    • Prompt fluid challenge
    • Emergent bedside echo
    • RV failure and reduced LV filling occur if primary arrhythmia not treated
      • Manage with cardioversion if unstable or antiarrhythmic meds (amiodarone vs. lidocaine vs beta blockers [no specific choice])
    • Use standard ACLS energy recommendations
    • Do not place defibrillator pads over the driveline

Stroke

  • Risk increases with MAPs >90 (ischemia and hemorrhage)

Pump failure

  • Inability to detect MAP
  • No sound on exam
  • May be due to control box malfunction
  • Treatment
    • IVF
    • Standard ACLS with epinephrine drip, heparin drip
    • If suspicion of clot consider VA ECMO early
    • If no response after 1 minute of above (fluids, epinephrine) CPR can be initiated (more below)

“Suckdown”

  • Occurs when patient’s septum or other part of heart is entrained into inflow cannula
  • Etiology
    • Decreased LV (from RV failure) volume
    • Cardiomyopathies
    • Arrhythmias
    • Cannula migration
    • Hypovolemia
    • Tamponade
  • Signs
    • Hypotension
    • Syncope
    • Arrhythmias
  • Treatment
    • Decrease RPM rate
    • IVF

Cardiac arrest

  • Avoid CPR at all costs if possible, it can theoretically dislodge the LVAD
  • Some first generation LVADs have hand pumps that can help with circulation
  • Evaluate for other causes of pump failure before doing compressions (i.e. thrombus, battery)
  • Check alarms, check the power. Call LVAD team!
  • If no flow, no hum, no MAP detectable, and the patient has not responded to any other measures, start ACLS like normal as a last ditch effort (i.e. start compressions and perform CPR)

Take Home Points

  • Always contact patient’s LVAD team to assist in care
  • Ensure controller is powered on and has backup battery
  • BP obtained with doppler, MAP should be between 70-90. Many will not have a pulse.
  • If hemodynamically unstable, try fluids first; LVADs are preload sensitive
  • If concern for thrombus, use tPA in emergencies
  • For cardiac arrests, evaluate for pump failure and then move to ACLS if epinephrine gtt unsuccessful

Read More

 

Resources

  • Aaronson KD, Slaughter MS, Miller LW. Use of an intrapericardial, continuous-flow, centrifugal pump in patients awaiting heart transplantation. Circulation 2012 June 26, 125 (25): 3191-200
  • Mancini, D. Practical management of long-term mechanical circulatory devices. UpToDate. Mar, 2018. Link: https://www.uptodate.com/contents/practical-management-of-long-term-mechanical-circulatory-support-devices
  • Winters M, et al. Emergency Department Resuscitation of the Critically Ill. Second Edition. Texas: American College of Emergency 2017: p145-154.
  • Miller LW, Pagani FD, Russell SD, et al. Use of a continuous-flow device in patients awaiting heart transplantation. N Engl J Med 2007; 357:885-896. PMID: 17761592
  • EM:RAP. Episode April 2019, Chapter 9
  • Tintinalli, Judith E., et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. Eighth edition. New York: McGraw-Hill Education, 2016: Section 7: 382.
  • Sen, A., Larson JS., Kashani, KB., Libricz SL, Alwardt CM, Pajaro O., et al. Mechanical circulatory assist devices: a primer for critical care and emergency physicians. Critical Care, 2016 Jun 25; 20(1): 153. PMID: 27342573