• Popular Recommendations

  • PEER
  • ultrasound
  • LLSA
  • sepsis

Emergency Ultrasound

Fellow Corner: E-point Septal Separation in the Patient with Congestive Heart Failure

By David Cisewski MD & Stephen Alerhand MD

 

Background

E-point septal separation (EPSS) was first described during the 1970’s, when there was growing interest in the noninvasive echocardiographic evaluation of the left ventricle (LV) [1]. When the LV relaxes during diastole, blood rushes through the mitral valve (MV), swinging open the anterior MV leaflet toward the interventricular septum (IVS). In the early stages of diastolic filling, the anterior MV leaflet reaches a point of maximum excursion, and as such comes closest to the IVS. This is the E-point. The distance in space separating the anterior MV leaflet from the septal wall is referred to at the E-point septal separation (EPSS). EPSS can be thought of most simply as an estimation of left ventricle contractility and ejection fraction.

How to Acquire EPSS and What it Means

EPSS can be measured by ultrasound visualization of the heart in the parasternal long axis (PLAX). Using M-mode, the marker is placed over the distal tip of the anterior MV leaflet. The M-mode image created using this point over time can be visualized as a cloudy sky over two hills. (Figure 1)

Figure 1 - E-point septal separation can be visualized as the space separating a mountain peak from the clouds (left). The clouds signify the straight M-mode lines measuring the movement of the IVS. There is typically little movement of the septum compared to the valve leaflets, creating a relatively homogenous streak of parallel lines across the anterior surface of the M-mode image. EPSS represents the distance separating the peak height of the MV – the E-point (E) - from the IVS motion during early diastolic filling on M-mode (right). The A-point (A) represents the atrial kick that occurs as the left atrium (LA) contracts, re-extending open the MV leaflet just prior to ventricular contraction.

 

M-Mode visualization

Physiological Description

E-Point

Peak 1

Early, rapid diastolic filling

A-point

Peak 2

Atrial contraction/kick

A normal, healthy anterior MV leaflet may come in contact with the septum creating zero distance of E-point separation.1 As a strained heart begins failing to pump against an elevated systolic afterload, the LV dilates. This dilation results in decreased contractile force, the consequences of which is a reduced LV ejection fraction (LVEF) - the original observation made by some early studies.1-3

These same research studies demonstrated an inverse correlation between EPSS and LVEF. As LV size expands to compensate for decreased stroke volume, the MV flow fails to keep pace, causing an increased separation between the valve and septum.1-3 Specifically, it was demonstrated that a EPSS > 7 mm was 87% sensitive and 75% specific at identifying reduced EF (<50%).3

Supporting Evidence for EPSS

EPSS has classically been used for estimation of LVEF and cardiac function. The technique is simple to learn, requires a single transthoracic view and single linear measurement, and perhaps most importantly, is not dependent on global ventricle contours or overall patient body habitus.4 Further studies have shown that EPSS offers a quantifiable value with limited subjectivity or inter-user variability as compared to some other techniques used.4,5 It has also been shown to indicate the presence of normal or abnormal LVFEF regardless of septal motion abnormalities.5

A major benefit of EPSS is the utilization of a single long-axis view.  In one prospective cross-sectional study, PLAX was shown to be the most favored cardiac view due to limited physiological barriers and optimal estimation of LVEF.4-6 In addition, the isolated bedside view requires limited patient repositioning and less bedside time spent on maneuvering the patient for optimal view.

Limitations of EPSS

Both mitral stenosis and aortic regurgitation can give false positive EPSS elevation, as both cause an abnormally increased distance between the MV and septal wall during diastole.1-3 As a result, the presence of valvular deformities or abnormalities may preclude the use of EPSS in estimating left ventricular function.

Use of EPSS in the ED

One prospective observational study demonstrated that EPSS measured by emergency physicians had close correlation with a quantitative, calculated LVEF as measured by transthoracic echocardiography (TTE).4 The observers in this study were emergency ultrasound fellows with training in both visual and calculated LVEF who underwent only a ten-minute didactic session on EPSS measurement. This success following a limited training duration suggests the possibility of a small learning curve for EPSS use.

Previous studies have demonstrated visual estimation of LVEF to correlate well with quantitative estimation. However, these studies were either limited to categorical estimation (low versus normal)7 or conducted in settings not comparable to the emergency department.8 In contrast, EPSS has been shown to produce LVEF estimations among emergency residents that accurately correlated with the visual estimation of experienced emergency physicians and trained cardiologists in an emergency setting.9 This evidence suggests EPSS could function as a complementary tool to be used by new emergency medicine residents and fellows as they gain experience – ie, experience that only comes with time - in visual estimations of cardiac function.

EPSS as a Continuous Variable

Expanding research has demonstrated that an estimate of LVEF could be extrapolated from the EPSS.10 The formula derived from their calculation (see below) allows EPSS to be utilized as a continuous variable in assessing LV function as opposed to the dichotomous classification of “normal” or “abnormal” provided by previous EPSS researchers. The strength of this study was in the use of MRI-derived LVEF as the reference standard, where close correlation and similar regression coefficients were demonstrated.

LVEF = 75.5 – (2.5 x EPSS)

Newer Data on EPSS

Despite the promise seen in early studies utilizing EPSS, widespread acceptance of the technique has not been demonstrated. Many argue that a lack of knowledge regarding the technique and failure to validate the Silverstein formulation for LVEF computation have been the major barriers to its popularity. Nevertheless, many centers continue to teach this as a risk stratification tool in patients with concerning cardiac functionality. A recent study once again demonstrated that a short didactic session using video clips to train novice sonographers on how to utilize EPSS resulted in a significant post-didactic improvement in the ability to differentiate normal (≤ 8 mm) versus elevated (> 8 mm) EPSS.11 This study was consistent with previous findings that short didactic sessions resulted in improved assessment of cardiac function.12-13 Though not quantifiable, these results do show the feasibility of a short training module to further the use of this tool with success.

EJECTION FRACTION

EPSS

Normal (≥ 50%)

≤ 8 mm

Abnormal (< 50%)

> 8 mm

A Tool for Risk-Stratification and Disposition

As emergency medicine physicians, we have confidence in identifying low-risk CHF patients. These are the patients who respond immediately to therapy, show no other evidence of ischemia or high-risk symptoms, and may be safely discharged with plans for close follow-up and return precautions. We can also identify the high-risk patients who demonstrate a limited response to treatment and/or signs of ischemia indicating a progressive decompensation. These are the patients we feel comfortable admitting to the hospital. However, it is the vast majority of intermediate-risk patients who show a partial response to treatment that remain a challenge to our disposition and for whom a further diagnostic assessment is required.

A report published in 2013 indicated that only a small fraction of the approximately 800,000 patients admitted to the hospital for CHF were in need of services beyond a period of observation.14 Despite admission, only a limited number of patients go on to receive advanced care or diagnostic testing beyond symptomatic treatment and IV diuretics; that is to say, very few require a level of monitoring beyond what could be provided in an observation unit. The authors of this study have argued there is a sizable subset of ED patients with heart failure who would benefit from a period of observation and symptomatic treatment, thus avoiding an inpatient admission.

The onus of this disposition ultimately falls on the emergency medicine team in first contact with the patient. The question remains, however, what do emergency medicine physicians have in their diagnostic tool belt that can be used to properly identify patients requiring admission versus observation/discharge? Many emergency physicians will allow the chest radiograph to guide their decision toward whether to disposition a patient to observation versus admission. However, this method lacks sensitivity as studies have demonstrated up to 15% of CHF patients in acute decompensation will lack radiographic evidence.15,16 With the advancements in ultrasonography and a recent push for bedside portable equipment use, a bedside echocardiogram continues to demonstrate the highest utility in risk stratification. Diagnostic proxies such as EPSS may prove to be a key to identifying the subset of CHF patients who could be safely observed for symptomatic treatment.

Conclusion

EPSS is a simple, easy to learn tool that allows a quick estimation of left ventricular function. The value of EPSS lies in its objective findings that do not require specialized training for interpretation and utilization. In patients without mitral or aortic valvular pathology, EPSS can be obtained from a single echocardiography view, providing quantifiable information on heart function within minutes. EPSS > 7 mm is typically cited as the cut-off for abnormal ejection fraction (<50%). EPSS offers a further tool for inexperienced emergency physicians that can be used to complement the overall assessment and risk stratification of patients with congestive heart failure.

References

1.      Massie BM, Schiller NB, Ratshin RA, et al. Mitral-septal separation: new echocardiographic index of left ventricular function. Am J Cardiol. 1977;39(7):1008-16.

2.      Strunk BL, Guss SB, Hicks RE, et al. Echocardiographic recognition of the mitral valve-posterior aortic wall relationship. Circulation. 1975;51(4):594-8.

3.      Ahmadpour H, Shah AA, Allen JW, et al. Mitral E point septal separation: a reliable index of left ventricular performance in coronary artery disease. Am Heart J. 1983;106(1 Pt 1):21-8.

4.      McKaigney CJ, Krantz MJ, La Rocque CL, et al. E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. Am J Emerg Med. 2014;32(6):493-7.

5.      Ginzton LE, Kulick D. Mitral valve E-point septal separation as an indicator of ejection fraction in patients with reversed septal motion. Chest. 1985;88(3):429-31.

6.      Mark DG, Ku BS, Carr BG, et al. Directed bedside transthoracic echocardiography: preferred cardiac window for left ventricular ejection fraction estimation in critically ill patients. Am J Emerg Med. 2007. 25(8);894-900.

7.      Unluer EE, Karagoz A, Akoglu H, et al. Visual estimation of bedside echocardiographic ejection fraction by emergency physicians. West J Emerg Med. 2014; 15(2):221-6.

8.      Shahgaldi K, Gudmundsson P, Manouras A, et al. Visually estimated ejection fraction by two dimensional and triplane echocardiography is closely correlated with quantitative ejection fraction by real-time three dimensional echocardiography. Cardiovasc Ultrasound. 2009;7:41.

9.      Secko MA, Lazar JM, Salciccioli LA, et al. Can junior emergency physicians use E-point septal separation to accurately estimate left ventricular function in acutely dyspneic patients? Acad Emerg Med. 2011;18(11):1223-6.

10.    Silverstein JR, Laffely NH, Rifkin RD. Quantitative estimation of left ventricular ejection fraction from mitral valve E-point to septal separation and comparison to magnetic resonance imaging. Am J Cardiol. 2006;97(1):137-40.

11.    Jacob M, Shokoohi H, Moideen F, et al. An Echocardiography Training Program for Improving the Left Ventricular Function Interpretation in Emergency Department; a Brief Report. Emerg (Tehran). 2017;5(1):e70.

12.    Moore CL, Rose GA, Tayal VS, et al. Determination of left ventricular function by emergency physician echocardiography of hypotensive patients. Acad Emerg Med. 2002;9(3):186-93.

13.    Randazzo MR, Snoey ER, Levitt MA, et al. Accuracy of emergency physician assessment of left ventricular ejection fraction and central venous pressure using echocardiography. Acad Emerg Med. 2003;10(9):973-7.

14.    Collins SP, Pang PS, Fonarow GC, et al. Is hospital admission for heart failure really necessary?: the role of the emergency department and observation unit in preventing hospitalization and rehospitalization. J Am Coll Cardiol. 2013;61(2):121-6.

15.    Collins SP, Lindsell CJ, Storrow AB, et al. Prevalence of negative chest radiography results in the emergency department patient with decompensated heart failure. Ann Emerg Med. 2006;47(1):13-8.

16.    Weintraub NL, Collins SP, Pang PS, et al. Acute heart failure syndromes: emergency department presentation, treatment, and disposition: current approaches and future aims: a scientific statement from the American Heart Association. Circulation. 2010;122(19):1975-96.

Return to Newsletter

LIVE CHAT
[ Feedback → ]