LVAD Part II: Diagnostic Evaluation

Left ventricular assist devices (LVADs) have moved from being a bridge to a heart transplant to destination therapy for patients with severe heart failure. Although their use in the general public has increased, they still provide a challenge to the emergency medicine (EM) physician This series aims to cover the basics of how the EM physician approaches the care of these patients. Last week we covered the physical exam. This week: the diagnostic evaluation.

Laboratory Workup

Workup laboratory tests in LVAD patients are generally similar to non-LVAD patients [4].

• There are no unique blood tests for LVAD patients and workup should proceed as indicated for the patient’s chief complaint.
• Blood gas and blood lactate are reasonable in patients who are short of breath since the pulse oximetry device is unlikely to have a reliable waveform. 
• A coagulation profile is indicated for all LVAD patients if bleeding or thrombosis is suspected since all LVAD patients are anticoagulated thus far on warfarin. 
• LDH and haptoglobin might be elevated slightly because of inherent hemolysis with the LVAD, but bilirubin should not be significantly elevated under normal circumstances.

Electrocardiogram

Obtaining EKG’s can be of little help in the LVAD patient [5]. When you obtain on you will usually find the following: (Figure A)

• Low limb lead voltage
• Ubiquitous electrical artifact
• QRS splintering

Imaging

Imaging can indicate gross placement abnormalities. 

• On Xray, the driveline can look disconnected due to some radiolucent components of the device [3].
• A computed tomography (CT) scan can show more precise dislocations (very rare) and pockets of infection (not uncommon).
• Magnetic resonance imaging (MRI) is strictly contraindicated because of the extensive metal in the LVAD and the magnets that drive the pump. 
• Ultrasound can be advantageous for the skilled user. It can give a rough estimation of systemic volume status, RV function, inflow cannula (should be aligned with the mitral valve), outflow cannula, and signs of pericardial effusion or tamponade [4].

Did you miss the LVAD introduction? Stay tuned for upcoming posts in the LVAD series. Next up: Complications

For an on-the-spot clinical reference, use ALiEM’s paucis verbis card for LVAD complications.

References

1. Heart Failure Factsheet. Division for Heart Disease and Stroke Prevention. https:// www.cdc.gov/DHDSP/data_statistics/fact_sheets/fs_heart_failure.htm. Published June 16, 2016. Accessed June 11, 2018. 
2. Kroekel PA, George L, Eltoukhy N. How to Manage the Patient in the Emergency Department With a Left Ventricular Assist Device. Journal of Emergency Nursing. 2013;39(5):447-453. doi: 10.1016/j.jen.2012.01.007. PMID: 22595685
3. Vierecke J, Schweiger M, Feldman D, et al. Emergency procedures for patients with a continuous-flow left ventricular assist device. Emergency Medicine Journal. 2016;34(12): 831-841. doi:10.1136/emermed-2015-204912. PMID: 27852651
4. Sen A, Larson JS, Kashani KB, Libricz SL, Patel BM, Guru PK, et al. Mechanical circulatory assist devices: a primer for critical care and emergency physicians. Crit Care. 2016 Jun 25;20(1):153. PMID: 27342573
5. Trinquero P, Pirotte A, Gallagher LP, Iwaki KM, Beach C, Wilcox JE. Left Ventricular Assist Device Management in the Emergency Department. West J Emerg Med. 2018 Sep;19(5):834-841. doi: 10.5811/westjem.2018.5.37023. Epub 2018 Jul 26. PMID: 30202496

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