EPSS As a Proxy for Ejection Fraction
Case:
A 68-year-old male presents to the emergency department (ED) with one week of worsening shortness of breath. He has no known cardiac history and has rarely seen a physician. He reports shortness of breath with exertion, mild non-productive cough, and subjective fever. He is not having chest pain. He is a long-time smoker but denies other drugs. Vitals are as follows: heart rate (HR) of 102, blood pressure (BP) of 105/70, afebrile, 89% on room air (RA), respiratory rate of 20. On exam the patient exhibits labored breathing, crackles in bilateral lower lung fields and +1 pitting edema in bilateral lower extremities.
Differential Diagnosis:
Heart failure, pneumonia, COPD
Discussion:
Shortness of breath is a common presenting complaint in emergency departments. The differential diagnosis is broad and elements of the history and physical often overlap with multiple pathologic etiologies. One of the most useful tools in differentiating etiologies is the point-of-care echocardiogram (echo). This rapid exam can offer an accurate estimate of cardiac function.[1] Many clinicians use the echo to gain a subjective estimate of ejection. However, there are alternative, more quantitative measures of ejection fraction (EF) such as E-point septal separation (EPSS)[2]
EPSS is a quantifiable metric obtained on echo that estimates EF. EPSS is the measured distance between the “e-point” and the interventricular (IV) septum. The e-point corresponds with the point in time when the mitral valve is opened maximally. In a normal functioning heart, the mitral valve should nearly strike the IV septum during ventricular diastole. A larger EPSS may represent a suboptimal EF while a smaller number (<0.6cm) may reflect a normal EF.[2]
EPSS is obtained in the parasternal long axis view. This view is obtained using the phased array probe, in the third or fourth intercostal space on the left chest wall with the probe marker towards either the patient’s right shoulder or left hip. After an adequate parasternal long view is obtained, motion-mode (M-mode) is selected and placed over the distal margin of the mitral valve’s anterior leaflet as shown below. M-mode creates a graphical representation of the objects under the m-mode line over time (displayed on the x-axis).[3] This allows one to more easily observe how objects under the line move with time. With EPSS we seek to observe the movement of the anterior mitral valve leaflet relative to the interventricular septum.
Figure 1
A normal EPSS tracing has two peaks as labeled below. First, is the e-point - this corresponds with maximum opening on the mitral valve in ventricular diastole (passive filling). As described above, the measurable distance between the e-point and the septum should be minimal. In fact, 7mm is the upper limit of normal and anything greater than this is a sign of potentially reduced EF.[4] The a-point, demonstrates the movement of the mitral valve during atrial kick.
Figure 2
There are a few limitations to the use of EPSS. Using the mitral valve to estimate EF is not accurate in cases of mitral stenosis as the leaflets do not move normally so use of EPSS could lead to a falsely low estimate of EF. EPSS is also not reliable in patients with aortic valve regurgitation as this also disrupts anterior movement of the mitral valve leaflet even when EF may be normal.[5]
Case continued and Conclusion:
After a thorough history and physical, point-of-care echo was obtained showing grossly reduced EF and an EPSS of 1.6 cm (well above the 0.7cm cutoff). Nitroglycerin was given, diuresis was started, and the patient’s respiratory status gradually improved. The patient was admitted for new onset heart failure. The use of EPSS facilitated a faster diagnosis, shorter time to treatment, and clearer communication with the emergency medicine team and admitting cardiology team. Laboratory analysis confirmed an elevated BNP and the comprehensive echo also showed a significantly reduced EF.
AUTHOR: Connor Wilson MD, MPH – Brown Emergency Medicine Resident
FACULTY REVIEWER: Kristin Dwyer, MD
References:
Moore C, Rose G, Tayal V, Sullivan D, Arrowood J, Kline J. Determination of left ventricular function by emergency physician echocardiography of hypotensive patients. Acad Emerg Med. 2002 Mar;9 (3):186-93.
Secko M, Lazar J, Salciccioli L, Stone M. Can junior emergency physicians use E-point septal separation to accurately estimate left ventriuclar function in acutely dyspneic patients? Acad Emerg Med. 2011 Nov;18(11):1223-6.
Turandot S, Sebastian D. Siadecki, Berkowitz R, Rose G, Matilsky D, Sauler A. M-Mode Ultrasound Applications for the Emergency Medicine Physician, The Journal of Emergency Medicine. 2015 Volume 49, (5):686-692
McKaigney C, Krantz M, La Rocque C, Hurst N, Buchanan M, Kendall J. E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. Am J Emerg Med. 2014 Jun;32(6):496-7
Saidecki, Sebastian. Bedside Ultrasound Assessment of Left Ventricular Function. ACEP now, ACEP, 3 Fe. 2015