No Pulse, No Panic! Navigating Cardiac Arrest in LVAD-Supported Patients

The increasing use of left ventricular assist devices (LVADs) for advanced heart failure presents new challenges in emergency care, especially during cardiac arrest. LVAD-supported patients often lack palpable pulses and may have unreliable blood pressure readings, complicating diagnosis. Management strategies vary, with debates over whether to delay chest compressions to troubleshoot the device or initiate immediate resuscitation. Recognizing cardiac arrest involves alternative assessments like end-tidal co ₂ and ultrasound. Limited evidence and inconsistent guidelines highlight the need for standardized protocols, training, and large registries to improve outcomes and guide best practices for prehospital and hospital management of LVAD patients experiencing cardiac emergencies.

Key points

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Identification of cardiac arrest in patients with a continuous-flow left ventricular assist device (LVAD) can be challenging because of an inability to palpate a pulse or use noninvasive blood pressure monitoring.
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Existing guidelines and algorithms for the management of cardiac arrests in LVAD-supported patients have variable recommendations but generally agree that delays in chest compressions should be avoided in most cases.
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Future research should investigate ways to improve the identification and management of care for the LVAD-supported patient in cardiac arrest.

Abbreviations

AHA	American Heart Association
eCPR	extracorporeal cardiopulmonary resuscitation
etco ₂	end-tidal capnometry
ILCOR	International Liaison Committee on Resuscitation
LVAD	left ventricular assist device
PI	pulsatility index
rpm	rotations per minute
VAD	ventricular assist device

Scope of the problem

The standard for treatment of advanced heart failure is heart transplantation, but this option is limited by a finite number of donor organs and patient-specific contraindications. Left ventricular assist devices (LVADs) are durable mechanical circulatory support devices that have become an important tool for supporting patients with advanced heart failure—either until heart transplantation or as a destination therapy. ^,^, Over the past two decades, the incidence of LVAD implantations has increased, with an increase from 107 cases per year in 2004 to 2464 in 2021 in the United States. ^, As the prevalence of patients with an LVAD is increasing, the need to resuscitate LVAD-supported patients in cardiac arrest will increase in tandem. Resuscitating these patients is challenging because of the device’s impact on traditional physical assessment, a multitude of device failure pathways, and concerns regarding device dislodgement or damage with chest compressions. ^,

Case study

A 26-year-old man with a history of idiopathic dilated cardiomyopathy and a nonpulsatile HeartMate 3 (Abbott, Lake County, IL) dials 9-1-1 to request help for problems with his LVAD. Paramedics arrive to find the patient complaining that water is lodged inside the LVAD and that it is making unusual noises. Initially, the patient has normal vital signs and a benign physical examination. After moving the patient to the ambulance, the patient begins to decompensate: the oxygen saturation drops from 99% to 55%; the blood pressure is unobtainable via automated blood pressure cuff, and the skin is cool, pale, and diaphoretic. The LVAD controller is alarming with flashing battery, heart, and wrench symbols. One paramedic begins to troubleshoot the LVAD while contacting the ventricular assist device (VAD) coordinating center number provided by the patient’s partner while the other paramedic prepares to intubate. An automatic blood pressure cuff does not provide a blood pressure reading and Doppler is unavailable. The LVAD is not humming on auscultation, and the VAD coordinator prompts examination of all driveline connections, which are patent. While the system controller and battery are being replaced under guidance from the VAD coordinator, the other paramedic has confirmed the endotracheal tube is in place with waveform capnography at a value of 16 mm Hg. Electrocardiographic rhythm is ventricular fibrillation. Because of signs of poor perfusion, defibrillation in the anteroposterior position is performed, and chest compressions are started. Routine advanced life support care is continued after all LVAD troubleshooting is unsuccessful, and paramedics initiate prompt transport to the closest cardiac center with an early notification to the facility. This case is based on elements from a published case report.

Overview of left ventricular assist device structure and function

The LVADs most frequently implanted in Europe and the United States are continuous flow devices, including the HeartWare HVAD (Medtronic, Minneapolis, MN), HeartMate II (Abbott, Lake County, IL), and HeartMate III. Based on a high 5-year postimplantation survival rate and low risk of LVAD-related adverse events, the HeartMate III is the only LVAD that is approved by the Food and Drug Administration and is currently available and implanted in the United States. ^,

The key features of the LVAD are visually represented in Fig. 1 . The heart is connected to an inflow cannula, which leads to a pump that drives flow into the aorta. This pump is attached to a driveline, which is fixed to an external controller, which leads to a battery and power source. Typically, an LVAD has a screen with visible parameters to evaluate the status of the device. These parameters are flow (liters per minute), rotations per minute (rpm), pulsatility index (PI), and power (watts). The flow does not directly reflect stroke volume, as rpm and power are used to calculate flow indirectly. PI indicates variability in LVAD flow and can be used to evaluate native heart function.

A medical diagram shows ventricular assist devices with external components, a blood pump, and flow direction for heart support. — Fig. 1

The challenge of identifying a left ventricular assist device–supported patient with cardiac arrest

In a patient not supported by an LVAD, cardiac arrest is identified by unresponsiveness and the absence of a pulse. Patients supported by continuous-flow LVADs, however, often do not have a palpable pulse at baseline, with an audible “LVAD hum” indicating some degree of functionality of the device. Noninvasive blood pressure and pulse oximetry measurements can be unreliable without pulsatility, and this is further complicated by artificial pulses—a feature of the Heartmate 3 that uses intermittent changes in rotor velocity to avoid pooling of blood and subsequent clot formation. ^,

Often, nonperfusing rhythms, such as ventricular tachycardia and ventricular fibrillation, can present in LVAD-supported patients with wide variability in hemodynamic status, with some patients having persistent stability and others having hemodynamic collapse. Although many patients may have an internal defibrillator implanted that terminates these rhythms, if rhythms persist, they may cause hemodynamic collapse secondary to decreased right-ventricular contractility and subsequent left-ventricular volume.

Recognition of cardiac arrest in a left ventricular assist device–supported patient

Clinical practice guidelines, expert statements, and algorithms have been developed to guide the initial approach to an LVAD-supported patient with suspected cardiac arrest. ^,^,^, Common to these approaches is a recognition that palpation for pulse, measurement of blood pressure, and assessment of pulse oximetry can be challenging. Alternative measures to assess perfusion and help determine whether clinical decompensation is due to LVAD or cardiac dysfunction are recommended, including assessment of responsiveness, chest auscultation for an LVAD “hum,” assessment of extremity temperature and capillary refill time, the use of end-tidal capnometry ( etco ₂), and vascular Doppler sonography. In hospitalized patients and in some prehospital settings, an arterial line may provide the most accurate measurement of blood pressure. etco ₂ may serve as a reasonable surrogate to measure perfusion in the unresponsive LVAD-supported patient. The American Heart Association (AHA) suggests using an etco ₂ cutoff of 20 mm Hg for the intubated patient to determine whether an LVAD-supported patient is in cardiac arrest, and that an etco ₂ higher than 20 mm Hg indicates that the patient may not be in cardiac arrest and the clinician should investigate other reversible causes of clinical decompensation. For this reason, early advanced airway placement should be considered in unresponsive LVAD-supported patients to allow for quantification of etco ₂. Point-of-care ultrasound may also be a useful tool to evaluate the function and potentially identify causes of device malfunction in LVAD-supported patients. ^,

Although LVAD-supported patients in the hospital or emergency department can be monitored with advanced and invasive modalities, prehospital clinician scope and available equipment have wide variability. These variations include the availability of capnography, vascular Doppler, invasive arterial catheters, and/or ultrasound. ^,^,^, Indeed, several reports have described delayed defibrillation and chest compressions in LVAD-supported patients with cardiac arrest in the prehospital setting. ^,^,^,^,^,

Management of cardiac arrest in left ventricular assist device–supported patients

The management of cardiac arrest in an LVAD-supported patient carries several important considerations. These include the duration of time since LVAD implantation, the availability of a cardiac surgeon, a theoretic (but unproven) potential for LVAD dislodgement with chest compressions, and the opportunity to address reversible causes of hemodynamic compromise. In Table 1 , some common arrest causes for cardiac arrest in LVAD-supported patients are described.

Table 1

Common arrest causes and key features of cardiac arrest in left ventricular assist device–supported patients

Arrest Cause	Key Features
Pump failure	This includes a loss of power, pump thrombus, driveline disconnection, and inflow/outflow pump obstruction
Underlying heart disease	This includes right-ventricular heart failure, cardiac tamponade, ventricular dysrhythmia, or increased afterload
Other	This includes obstructive physiology from a tension pneumothorax or pulmonary embolism, respiratory failure, and distributive shock

The Peri-Implantation Phase of Care

Limited data exist to guide the management of LVAD-supported patients who suffer cardiac arrest in the peri-implantation phase of care (often considered 10 days after implantation, but definitions can vary). As patients are often still in the hospital at this time point, physiologic monitoring and advanced diagnostic approaches can be used to identify both the cardiac arrest and the arrest cause. In LVAD-supported patients in the peri-implantation phase, recognition of cardiac arrest (or impending arrest) should be promptly followed by emergency contact of the cardiac surgical team—with subsequent care, including whether to provide chest compressions, decided as part of a multidisciplinary team. One survey of LVAD coordinators, surgeons, and cardiologists reported wide variation in whether to perform chest compressions during cardiac arrest in LVAD-supported patients, and less than half of those surveyed reported a distinct policy for a peri-implantation phase cardiac arrest. Although few studies have explored device dislodgement with chest compressions in the peri-implementation phase, no device dislodgement has been reported.

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