June 2024

Author: Dr. Charles Pan, MD

Peer Reviewers: Dr. Lauren Kaplan, MD

Faculty Editors:
Dr. Angela Barskaya, MD, Assistant Professor of Emergency Medicine at Columbia University Medical Center
Dr. Liza Hartofilis, MD, Assistant Professor of Emergency Medicine at Columbia University Medical Center and Assistant Medical Director at NewYork-Presbyterian Westchester

The authors of this article have no financial or industry relationships to disclose.

Case: You respond to the resuscitation bay for an unannounced EMS notification. They are arriving with a 67 year old male with a past medical history of hypertension, diabetes, end stage renal disease on hemodialysis, upper gastrointestinal bleeding, coronary artery disease and ischemic cardiomyopathy complicated by VT arrest and biventricular failure now s/p AICD and HeartMate 3 LVAD six years prior, and newly diagnosed prostate cancer. The patient’s family activated EMS due to a prolonged period of decreased responsiveness. They deny any trauma nor any low flow alarms at home. Upon your arrival, nursing is having difficulty obtaining a pulse oximetry waveform and you note the patient is not having any spontaneous respirations. What is your next course of action?

LVAD Anatomy:

LVADs (Left ventricular assist devices) are surgically placed devices most commonly used to improve survival and quality of life in patients with advanced heart failure. The current generation of LVADs are known as continuous flow centrifugal pumps, and they function by mechanically pumping blood from the left ventricle to the body. LVADs are utilized for a variety of indications, including bridge to cardiac transplantation, bridge to cardiac recovery, or destination therapy. It is paramount for emergency providers (EPs) who work at centers with cardiology and cardiothoracic surgery subspecialists who implant and manage LVADs to be familiar with the basic anatomy, which is depicted in Figure 1 below. Additionally, EPs who practice at centers without the aforementioned specialty services have even more stakes in understanding LVADs as they will be the primary providers managing these patients as they await transfer to a higher level care facility.

***Figure 1.*** *Depiction of continuous flow LVAD with its major components*
Vaidya Y, Riaz S, Dhamoon AS. Left Ventricular Assist Devices. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499841/

The LVAD itself is placed into the patient’s chest by means of a sternotomy. Blood flows into the inflow cannula in the left ventricle and is returned to native circulation in the ascending aorta via a new anastomosis through the outflow graft. The driveline connects the internal components of the LVAD with the external controller. The controller is powered by two battery packs that must be worn by the patient. Patients are educated on the critical importance of having backup batteries in close proximity at all times. When troubleshooting an LVAD, EPs should interrogate the controller to display the LVAD parameters, and comparing the results to prior or baseline numbers can help EPs better evaluate and manage a critically ill LVAD patient. The typical LVAD parameters are speed, power, flow, and pulsatility index. The only parameter that is independently set by the clinician is the LVAD speed. For the purposes of this discussion, detailed explanations regarding the significance of each parameter will not be covered.

LVAD Complications

While LVADs are potentially life-saving in patients with advanced heart failure, they are also susceptible to a wide range of complications. Due to LVAD patients requiring systemic anticoagulation, it is unsurprising that bleeding/hemorrhage is the most common complication seen, with up to 70% of patients experiencing an episode. LVADs are also significantly at risk of driveline infections, which should be treated with broad-spectrum antibiotics, as well as arrhythmias. Most patients who have LVADs already have pre-existing AICDs due to ischemic cardiomyopathy; an LVAD patient who is presenting with an unstable arrhythmia can, and should, be given medications or electricity to terminate the arrhythmia as in any other patient. Never disconnect any components of the LVAD before cardioversion or defibrillation. For a select few patients with refractory arrhythmias, VA ECMO (veno-arterial extracorporeal membrane oxygenation) can be offered as a salvage therapy.

Cerebrovascular accidents are another source of morbidity and mortality for LVAD patients, with patients being at higher risk for both thromboembolic and hemorrhagic strokes. As with any other instance of life-threatening bleeding, reversal of anticoagulation should be initiated if the patient is found to have an intracranial hemorrhage. Interestingly, while neither intravenous thrombolytics nor endovascular procedures are routinely recommended for LVAD patients who are found to have ischemic strokes without hemorrhage, there are reports of patients who have received systemic thrombolytics safely. A rapid and multidisciplinary discussion between cardiology, cardiac surgery, and vascular neurology must be facilitated prior to the administration of any systemic thrombolytics in an LVAD patient.

Case, continued: On your evaluation, the patient is unresponsive and you cannot obtain either a good peripheral oxygen saturation waveform, nor a Doppler MAP. There is no spontaneous chest rise, and the patient’s extremities are cool and mottled. There is no palpable pulse. An LVAD hum is patent. You immediately start chest compressions and the patient is intubated successfully. Bedside point of care ultrasound revealed an underfilled left ventricle and no organized cardiac activity (PEA) on first pulse check. You hear the LVAD alerting with loud low flow alarms, thus you pressure bag fluids and transfuse emergency uncrossed blood. ACLS is continued for multiple rounds, with the patient receiving epinephrine, amiodarone, lidocaine, and high quality chest compressions. He also receives magnesium and calcium. Rhythm checks reveal a pulseless wide complex tachycardia multiple times. Subsequently, the patient is noted to have return of faintly palpable pulses corresponding with native cardiac contractility on ultrasound. A Doppler MAP of 30 is noted, and you start an epinephrine drip. However, findings such as a grossly positive FAST exam, fixed and pinpoint pupils, and absence of corneal or gag reflexes prompts an extensive discussion with cardiac surgery about next steps for the patient. After a multidisciplinary meeting with family, a decision was made to admit the patient to the cardiothoracic ICU for formal brain death testing.

LVAD Patients In Extremis: Patients with LVADs presenting to the emergency department in extremis require special considerations, due to their lack of pulsatile flow. You may be able to palpate peripheral pulses in an LVAD patient, but this will not always be present. Remember that non-invasive MAP measurement on an LVAD patient is obtained by deflating a blood pressure cuff until the return of flow as detected by a Doppler signal. An arterial line should be placed as soon as possible in all circumstances to provide real time MAP measurements. However, the general principles of fundamental resuscitation remain the same as patients without LVADs, starting with Airway, Breathing, and Circulation. However, due to differing hemodynamics, the following stepwise approach is adapted from AliEM and provides another “ABC” paradigm to consider when resuscitating a patient with an LVAD:

If the LVAD hum is absent despite battery replacement or connection to a wall outlet, then the LVAD should be assumed to be nonfunctional and ACLS should proceed without any deviation from standardized guidelines in the appropriate clinical context. If the LVAD hum is patent and the batteries are functional, interrogation of the controller and alarms can often indicate an underlying pathology. Low flow alarms indicate suction events, occurrences where an underfilled left ventricle or a distended right ventricle due to right heart failure or cardiac tamponade causes adherence of the inflow cannula to the interventricular septum. The controller will reveal decreased flow due to decreased preload into the LVAD causes decreased cardiac output and often manifests as shock; volume resuscitation and point of care ultrasound can help the clinician guide management. Separately, elevations in power output suggest LVAD thrombus. In both cases of suction events/decreased preload or pump thrombus/elevated afterload, the LVAD speed will also deviate lower from its preset baseline. Obtaining point of care echocardiography can be difficult due to simultaneous compressions or distorted cardiac anatomy, but it is still important to try to assess LV contractility, IVC size, and cardiac activity in real time during resuscitations.

LVADs in Cardiac Arrest: Chest compressions have long been controversial, due to fears of dislodging or damaging an LVAD. Furthermore, patients who receive LVADs often have underlying cardiac dysfunction predisposing them to ventricular dysrhythmias, but a functioning LVAD may maintain adequate forward flow despite an otherwise lethal arrhythmia for some time though likely not indefinitely.. However, remember that the LVAD only assists the left ventricle, and the right ventricle may not be able to continue maintaining adequate preload into the LV, thus rendering the LVAD essentially nonfunctional.If the patient is conscious, compressions should not be started. A 2017 AHA Consensus Statement notes that “assessment of adequate tissue perfusion is the most important factor in determining the need for chest compressions, and clinical findings such as skin color and capillary refill are reasonable predictors of the presence of adequate flow and perfusion.” The lack of a blood pressure or a low pulse oximetry reading may not represent true hypoperfusion or hypoxemia and should not be relied upon as tools to guide chest compressions. This is due to the fact that not all LVAD patients will have pulsatile blood flow. Rather, the post intubation end tidal capnography may be the most important measure in evaluating perfusion in an LVAD patient. Generally, even if the LVAD is functional, if the patient is unresponsive with signs of impaired perfusion with MAP < 50 mmHg, end tidal < 20 mmHg, decreased mentation, or abnormal cardiac contractility, external chest compressions should be initiated and ACLS protocols should be followed, including the administration of ACLS medications and/or defibrillation/cardioversion when indicated. The algorithm for unresponsive LVAD patients is shown below.

***Figure 4.*** *AHA algorithm for the unresponsive LVAD patient*
Peberdy MA, Gluck JA, Ornato JP, Bermudez CA, Griffin RE, Kasirajan V, Kerber RE, Lewis EF, Link MS, Miller C, Teuteberg JJ, Thiagarajan R, Weiss RM, O'Neil B; American Heart Association Emergency Cardiovascular Care Committee; Council on Cardiopulmonary, Critical Care, Perioperative, and Resuscitation; Council on Cardiovascular Diseases in the Young; Council on Cardiovascular Surgery and Anesthesia; Council on Cardiovascular and Stroke Nursing; and Council on Clinical Cardiology. Cardiopulmonary Resuscitation in Adults and Children With Mechanical Circulatory Support: A Scientific Statement From the American Heart Association. Circulation. 2017 Jun 13;135(24):e1115-e1134.

The historical fears of dislodging, displacing, or damaging components of an LVAD during chest compressions have largely been debunked. In one retrospective case series, autopsies of LVAD patients who received chest compressions did not reveal any disruption or dislodgement of the inflow or outflow cannulas. There is a case report of abdominal compressions as an alternative to chest compressions in an LVAD patient, but this practice is generally not recommended in current clinical practice. Another suggestion involves compressing the right ventricle if the LVAD is determined to be patent, as the LVAD continues to provide systemic circulation. As transesophageal echocardiography (TEE) becomes more prevalent in emergency departments, EPs can utilize TEE as a means of evaluating and optimizing location and quality of chest compressions. It should be noted, however, that external defibrillator pads should not be placed directly over the LVAD. However, review of current literature did not yield any studies indicating preference for pad position (anterior-posterior vs anterior-lateral). As with any resuscitation, there needs to be minimal interruptions in chest compressions when applying external defibrillation pads. Table 1 below summarizes the most common differential diagnoses for an unresponsive LVAD patient and is adapted from an editorial by M. Guglin: This provides a high yield and easy to remember summary of the different scenarios EPs may face with LVAD patients presenting in extremis.

Case resolution: Given multiple comorbidities, the patient was not a candidate for ECMO nor heart transplant. After transfer to the ICU, the patient’s wife agreed to transition to comfort care with cessation of all life sustaining measures including pressors, inotropes, and cardiorespiratory support. The patient was compassionately extubated and his LVAD support was terminated, and the patient expired two minutes later.

References:

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