Left Ventricular Assist Device Management in the Emergency Department

Paul Trinquero, MD; Andrew Pirotte, MD; Lauren P. Gallagher, MD, MA; Kimberly M. Iwaki, MD; Christopher Beach, MD; Jane E. Wilcox, MD

Disclosures

Western J Emerg Med. 2018;19(5):834-841. 

In This Article

Initial Approach and Emergency Department Management

Evaluation, management, and troubleshooting for patients with a VAD represent a unique clinical challenge as the presence of a mechanical support device changes native cardiovascular physiology. The evaluation of the stable VAD patient is similar to other patients, and should appropriately address the chief complaint. Because seemingly minor ailments can mask more significant pathology, the VAD team/coordinator should always be contacted. This will mobilize appropriate resources and facilitate communication. In hospitals with a cardiothoracic intensive care unit or VAD unit, evaluation of VAD patients (particularly vital signs) can often be facilitated through the services of the on-call VAD nurse/tech/physician. Given the complexity and increase in utilization of durable mechanical support devices, it is appropriate for all EDs and urgent care facilities to have a written protocol in place to provide optimal care for patients with VADs.

Primary ED evaluation begins with a full history, physical, and evaluation of the device (Figure 1). Heart rate is variable depending on the patient's intrinsic rate and rhythm. Many patients with VADs also have cardiac pacemakers or implantable cardioverter defibrillators (ICD) in place. The continuous-flow VAD device does not generate a pulse, but patients may have enough residual or recovered ventricular function to mount intrinsic pulsatile flow. Because the degree of pulsatility is variable among VAD patients, a standard approach to measuring a blood pressure is recommended (Figure 2). Given the continuous-flow pump characteristics, measuring the mean arterial pressure (MAP) is the most reliable measure of perfusion pressure and is standard of care for VAD patients. First, palpate the radial artery. If a pulse is present and consistent, obtain a blood pressure using a standard sphygmomanometer. If unable to obtain a blood pressure reading or if there is no pulse, use the Doppler method to obtain the MAP: Place a pencil Doppler probe over the brachial (or radial) artery and inflate a blood pressure cuff 30 millimeters of mercury (mmHg) past when the arterial pulse is no longer detected by Doppler. Slowly deflate the cuff until arterial flow is once again audible. The corresponding pressure is the MAP. If unable to reliably measure MAP using the Doppler method, consider an arterial line to evaluate perfusion. Due to continuous flow, the arterial line waveform will often remain flat or have minimal pulse pressure.

Figure 1.

Emergency department approach to VAD patient.
VAD, ventricular assist device; HPI, history of present illness; CT, computed tomography; ICH, intracranial hemorrhage; EKG, electrocardiography; AMS, altered mental status; MAP, mean arterial pressure; RPM, revolutions per minute; PI, pulsatility index; PT, patient; ACLS, advanced cardiovascular life support; CXR, chest x-ray; CBC, complete blood count; Hb, hemoglobin; WBC, white blood cell count; LDH, lactic acid dehydrogenase.

Figure 2.

Obtaining a blood pressure (BP) for patient with Ventricular Assist Device.
MAP, mean arterial pressure.

Continuous-flow devices are very sensitive to afterload. Higher mean arterial blood pressures lead to increased afterload on the device and may lead to decreased pump flow. Clinically, this may manifest as worsening symptoms of HF. Increased afterload can also lead to subendocardial ischemia, which may potentiate ventricular arrhythmias. Adequate MAP control is essential in VAD patients; current guidelines recommend a target MAP <80 mmHg as long as symptomatic hypotension can be avoided.[4] The Interagency Registry for Mechanically Assisted Circulatory Support has defined a hypertension adverse event as MAP >110 mmHg for continuous-flow pumps.[6] Angiotensin-converting-enzyme inhibitors and beta blockers are the preferred agents for outpatient management of blood pressure.[2] Oral hydralazine is often a preferred antihypertensive agent for reducing blood pressure in the ED.

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