Cardiac activity in an awake L”>American Journal of Emergency Medicine 35 (2017) 1041.e1-1041.e3

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Case Report

Organized cardiac activity in an awake LVAD patient during ventricular fibrillation

Mike Butterfield, MD, MS, MPH ^a,?, Charlotte Derr, MD ^a,

Jotham Keffeler, RN, BSN, EMT-P ^b, Tom Jelic, MD, FRCPC ^a

^a Tampa General Hospital, University of South Florida, Emergency Medicine Residency Program, Tampa, FL, United States

^b Aeromed Transport, Tampa General Hospital, Tampa, FL, United States

a r t i c l e i n f o

Article history:

Received 26 February 2017

Accepted 1 March 2017

Keywords:

LVAD

Ultrasound Ventricular fibrillation

(C) 2017

We present the case of a 73-year-old man with a Heartware left ven- tricular assist device (LVAD) who presented to the emergency depart- ment with lightheadedness due to sustained ventricular fibrillation. Bedside echocardiography, however, clouded the clinical picture by displaying apparent organized cardiac activity with regular opening of the mitral valve, a likely consequence of the negative pressure produced by the LVAD. While bedside echocardiography is certainly useful in evaluating symptomatic LVAD patients, recognition of potential inter- pretive errors can prevent confusion and delays in management.

A 73-year old man was brought in by ambulance after becoming lightheaded hours earlier. At that time, he had noticed that the flow on his Heartware(C) left ventricular assist device had briefly de- creased, with an associated rise in the machines revolutions per minute (RPMs). At the advice of his LVAD coordinator, he began to drink several glasses of water and called an ambulance to bring him in.

On arrival, the patient was awake and conversant, though mildly con- fused. His odd demeanor had caused both the emergency medical techni- cians and emergency physicians to suspect alcohol intoxication, which he denied. His initial mean arterial pressure (MAP) was 58 and recorded heart rate was 149, with unlabored respirations and an oxygen saturation of 100% on two liters nasal cannula. He had clear lungs, a high-pitched “hum” over the precordium, and no palpable pulses. The Heartware set- tings, ascertained from the patient’s controller, were all within normal ranges: a flow rate of 5 l/min, using 5.3 V of power at a speed of 3000 RPMs.

* Corresponding author at: 1 Davis Boulevard, Suite 504, Tampa, FL 33606, United States.

E-mail address: [email protected] (M. Butterfield).

Interrupting this normal initial evaluation was the patient’s EKG, which showed an irregular, disorganized rhythm highly concerning for ventricular fibrillation and markedly different from his most recent prior EKG (Fig. 1). Due to the patient’s clinical stability, electrical pads were placed, an amiodarone infusion was begun, and bedside echocar- diography was performed.

Unexpectedly, the patient’s heart, in the parasternal long view, appeared to have organized cardiac activity, with regular mitral valve opening and very modest ventricular contraction (Fig. 2, Videos 1 and 2). Given the conflicting findings between the patient’s EKG and bedside echo, along with his continued clinical stability, cardiology was consulted to bedside. At their recommendation, the patient was defibrillated at 200 J and subsequently returned to sinus rhythm (Fig. 3). Post-defibrillation echo showed significantly improved cardiac function (Videos 3 and 4).

Ventricular arrhythmias are very common in patients with LVADs. A recent review estimated nearly 33% experience an episode of sustained ventricular arrhythmia (N 30 s), with the highest incidence in the first postoperative month [1]. Therefore, patients are typically equipped with an automatic implanted cardioverter-defibrillator (AICD), but our patient’s AICD had been removed because of recurrent infections.

That LVAD patients may tolerate otherwise terminal arrhythmias with no or minimal symptoms is testimony to the degree to which the device supplants their native cardiac function [2,3]. What remains less clear is how the supported left ventricle receives adequate preload from the unsupported right ventricle during these episodes. As in our case, it would appear that the negative pressure generated by the device’s continuous rotary motor is great enough to draw blood through the mitral valve at regular intervals. Similarly, continuous rotary or axial

http://dx.doi.org/10.1016/j.ajem.2017.03.001

0735-6757/(C) 2017

1041.e2 M. Butterfield et al. / American Journal of Emergency Medicine 35 (2017) 1041.e1-1041.e3

Fig. 1. Initial EKG showing ventricular fibrillation in a 73-year old man with an implanted LVAD.

Fig. 2. Bedside echocardiogram with regular opening of mitral valve.

LVADs are well-known to produce enough negative force to cause “suckdown” of the left ventricle and (less commonly) left atrium, and may also cause continuous mitral valve opening [4-6].

Nevertheless, it is imperative to return even asymptomatic patients with ongoing ventricular arrhythmias to sinus (or paced) rhythm as quickly as possible, since their ability to maintain adequate preload re- mains tenuous.

The contradictory findings between the ECG and bedside ultra- sound produced a clinical conundrum for the emergency physicians at the time, since the combination of a well-appearing patient, stable vitals and device settings, and what appeared as organized cardiac activity called the diagnosis of ventricular fibrillation into question.

While the aortic valve was unfortunately not well-visualized prior to defibrillation, it is unlikely to have been able to help distinguish true car- diac activity, since LVAD device settings are typically optimized with echocardiography in the perioperative setting to minimize opening of the aortic valve [7]. In patients with severely reduced native function, the valve leaflets may fuse and cease opening at all [8].

Fig. 3. Post-defibrillation EKG with return of sinus rhythm.

M. Butterfield et al. / American Journal of Emergency Medicine 35 (2017) 1041.e1-1041.e3 1041.e3

Bedside echo for LVAD patients in distress may be useful in quickly identifying or ruling in/out pathology (dehydration, suction events, thrombosis, tamponade or Pulmonary findings such as interstitial edema). Our experience suggests, however, that the appearance of ap- parent cardiac activity may be misleading when ventricular fibrillation is suspected, and that Point of Care Ultrasound be used as a data point, rather than definitive diagnosis.

Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.ajem.2017.03.001.

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