Management of Emergencies in Patients with Left Ventricular Assist Devices

Educational Objectives

The goal of this program is to improve management of patients with left ventricular assist devices (LVADs). After hearing and assimilating this program, the clinician will be better able to:

1. Recognize signs of dysfunction in patients with LVADs.
2. Anticipate adverse effects of implantation of LVADs.

Summary

Left ventricular assist device (LVAD): acts as a pump for the heart; pumps blood from a failing left ventricle (LV) into the aorta; right ventricular assist devices and biventricular assist devices are available; LVAD is the only approved durable device; the main indication for LVAD is heart failure with end organ dysfunction; LVADs may be temporarily used in patients waiting for heart transplantation, with recoverable conditions (eg, cardiomyopathy) or requiring destination therapy; LVADs are used to improve quality of life in patients not qualified for heart transplantation; LVADs consists of 6 components, ie, inflow cannula, pump, outflow conduit or graft, percutaneous driveline, external controller, and a battery

Prevalence of complications: 50% of patients with a newly placed LVAD present to the emergency department <1 mo after discharge and 7 times in <1 yr after implantation

Assessment: LVADs produce an audible mechanical hum; patients with continuous flow LVADs have a narrow pulse pressure; a manual mean arterial pressure (MAP) reading should be taken during assessment; MAP should be assessed with an arterial line; routine laboratory work-up should be carried out based on the chief complaint; additional investigations include levels of lactate dehydrogenase (LDH), plasma-free hemoglobin, haptoglobin (for hemolysis as red blood cells may lyse when passing through the LVAD), and lactate; patients on LVADs receive warfarin (Coumadin); international normalized ratio (INR) should be frequently monitored in patients on warfarin

Components of the LVAD controller: include lights, battery power gauge, low battery alarm, device malfunction alarm, device function warning alarm (also known as yellow alarm), cable disconnect symbols, and driveline connect button; the patient should be connected to 2 batteries; the button on the back side is used to display pump speed in revolutions per minute (RPM), power, flow, and pulsatility index (PI); HeartMate 3 is the most common LVAD used in the United States; RPM is between 3000 and 9000 RPM, and normal speed is 4000 to 6000 RPM; RPM is the only setting able to be adjusted; power refers to the watts required to pump at a specified RPM; power is a calculated value; flow corresponds to cardiac output (ie, how much flow the LVAD is providing), which is calculated based on patient factors such as vascular resistance, hemoglobin levels, and blood viscosity; PI is a mathematical difference between maximum and minimum power divided by the average power in one cardiac cycle; PI is based on calculated flow and is averaged over 15 sec and represents the equilibrium between native cardiac function and the LV pre-loading by the LVAD

Alarms: a beeping yellow may indicate low battery, that a power cables is unplugged, a data communication error, or a damaged driveline wire; red is a continuous loud alarm which may indicate a switched-off pump, persistent low flow, disconnected driveline, or disconnected power cables; a red alarm indicates that the patient is most likely in shock

LVAD-related complications: LVAD-related issues include pump failure, cannula or pump obstruction (presents as thrombosis), conduit kinking or incorrect pump speed; non-LVAD-related cardiac issues include hypovolemia, hemorrhage, dehydration, ventricular arrhythmias, right ventricular failure, cardiac tamponade, and aortic valve regurgitation

Pump thrombosis: a clot in the pump or outflow conduit; occurs in 1% to 2% cases after implantation; obstructive shock causes a low-flow state which triggers low-flow alarms; falsely elevated flow may be indicated because the LVAD cannot calculate flow correctly; poor perfusion and shock are characteristic clinical features; diagnosis is made by echocardiography, computed tomography (CT) or clinically; treatment is 5000 units of heparin; a cardiologist should be consulted in cases of patients who are rapidly decompensating without output from the LVAD

Suction events: the LV may collapse because of negative pressure from the pump pulling too much volume out of the LV, which results in low-flow states, low PI, and alarms; PI events are usually associated with low-flow states in true suction events; a PI event refers to a change of 45% in PI; PI events most commonly occur because of hypovolemia, and rarely because of arrhythmias; treatment is fluids; the cardiology team may adjust speed

Changes in PI: high PI related to recovery of the left ventricle may be assessed with echocardiography; low PI may be caused by hypovolemia, very poor native function, or excessive pump speed; PI is managed with fluids, inotropic support, and speed adjustment

Arrhythmias: not uncommon and generally better tolerated; arrhythmias may include ventricular tachycardia (treated with antiarrhythmics), torsades de pointes (amiodarone), atrial fibrillation, and atrial flutter; risk for stroke is low in patients with arrhythmias because of administration of warfarin

Non-LVAD-related complications: include infection; the most common organisms are Staphylococcus and Pseudomonas; vancomycin and piperacillin/tazobactam (Zosyn) are acceptable starting antibiotics for patients with LVADs; the driveline is the most commonly infected site; bleeding is common and may be related to warfarin; patients with LVADs may develop an acquired von Willebrand factor deficiency because of the shearing forces on the blood as it passes through the pump; lack of pulsatile circulation of blood leads to formation of arteriovenous malformations (AVMs), commonly in the gastrointestinal tract, which leads to gastrointestinal bleeds; may occur after 1 to 2 wk; bleeding may occur throughout the body, eg, the gastrointestinal tract, central nervous system (CNS), retroperitoneum, intra-abdominally, intrathoracically

Reversal of anticoagulation: the HeartMate 3 has a low risk for stroke; stroke risk with HeartMate 2 is higher; anticoagulation therapy is not recommended to be reversed except in cases of CNS hemorrhage or life-threatening hemorrhage; anticoagulation should not be reversed for smaller bleeds

Resuscitation: the basic ABC protocol for resuscitation should be followed; patients with LVADs may be intubated; the LVAD only supports the LV; intubation may have adverse effects on patients with right ventricular failure; a low threshold for starting inotropes to support the right ventricle may be appropriate; chest compressions are generally not indicated in patients with LVADs unless the LVAD is failing; according to American Heart Association guidelines, chest compressions should be performed in patients who are unresponsive with a MAP of 40 mm Hg, end-tidal carbon dioxide <20 mm Hg, and non-functioning LVAD

Final considerations: calling the patient’s LVAD coordinator or the nearest LVAD center for consultation early in the patient’s presentation is recommended; tertiary institutions that perform LVAD implantation have active heart failure services and a VAD coordinator available 24 hr/day, 7 days/wk; patients with LVADs who require admission to an intensive care unit require that the unit be familiar with their device

Readings

de la Espriella R, Santas E, Zegri Reiriz I, et al. Quantification and treatment of congestion in heart failure: A clinical and pathophysiological overview. Nefrología (English Edition). 2022;42(2), 145–162. https://doi.org/10.1016/j.nefroe.2021.04.007; Hockstein MA. Continuous-flow left ventricular assist devices: Management in the emergency department. J Am Coll Emerg Physicians Open. 2020;1(4):362-370. Published 2020 Jul 11. Doi:10.1002/emp2.12178; Stemple K, DeWitt KM, Porter BA, et al. High-dose nitroglycerin infusion for the management of sympathetic crashing acute pulmonary edema (SCAPE): A case series. The American Journal of Emergency Medicine. 2021; 44, 262–266. https://doi.org/10.1016/j.ajem.2020.03.062.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Wallis was recorded at the Rocky Mountain Winter Conference on Emergency Medicine, held February 26 to March 1, 2023, in Breckenridge, CO, and presented by the Well Assembled Meetings, LLC. For information about upcoming CME activities from this presenter, please visit wellassembled.com/events. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.50 CE contact hours.

Lecture ID:

EM410703

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.