What You Need to Know About LVAD Alarms and Malfunction

LVAD emergencies are usually not pump failure; about 90% of ED visits in patients with LVADs are for non-device problems. The bedside approach starts with a precordial hum, battery and controller checks, and alarm interpretation that can quickly separate suction events, pump thrombosis, and mechanical failure.

LVAD bedside assessment and alarms

• Core ED reality check: Most LVAD patients are critically ill heart-failure patients, but roughly 90% of presenting complaints are unrelated to LVAD malfunction, so keep a broad emergency differential alongside the device evaluation.
• ABCs with a hum: A continuous precordial mechanical hum is the quickest bedside sign that the pump is running; absent hum should immediately raise concern for mechanical failure.
• Battery and controller basics: Power comes from two or more rechargeable battery packs with about 16-18 hours of life, and patients need their own charger for wall power in the ED.
• Patient-specific baseline metrics: Controller numbers matter most when compared with the patient’s usual baseline, and patients themselves can often tell you which alarm fired and what is abnormal.
• Alarm pattern recognition: Low-flow alarms point toward suction events, while high power with low flow suggests pump thrombosis. We walk through how to read those patterns in the episode.

Major LVAD malfunctions

• Suction event physiology: A suction or suck-down event is a preload problem: the LV collapses against the inflow cannula, causing transient obstruction, low-flow alarms, and sometimes syncope.
• Reversible precipitants to find: Think hypovolemia, tamponade, massive PE, tension pneumothorax, or RV failure with septal shift; treatment is fixing the cause rather than changing the LVAD yourself.
• Mechanical failure red flag: Loss of hum suggests pump failure or power interruption from battery, controller, cable, or driveline problems, and unstable patients may need immediate hemodynamic support.
• Restarting a stopped pump: Pump interruption carries thrombus risk, so stable patients should have the LVAD team involved before restart, while unstable patients may need restart first despite that hazard.
• Pump thrombosis pattern: Pump thrombosis classically produces high power and low flow because the device is working harder against obstruction, often with hemolysis clues such as dark urine and elevated LDH.
• Driveline fracture clues: Low flow, low speed, or low power alarms can indicate driveline fracture; AP and lateral chest-abdomen films help, and driveline manipulation should be specialist-guided. The stabilization nuance is worth hearing in the chapter.

References:

1. Peberdy MA, Gluck JA, Ornato JP, et al. Cardiopulmonary Resuscitation in Adults and Children With Mechanical Circulatory Support: A Scientific Statement From the American Heart Association. Circulation. 2017;135(24):e1115-e1134. PMID: 28533303.