A paper in AJEM describes a way to quickly assess left ventricular function that I wasn’t too familiar with. By measuring the distance between the anterior mitral valve and interventricular septum we can roughly assess the heart’s ejection fraction.
Systolic heart failure (SHF) is for our purposes is inadequate emptying of the left ventricle, ie increased preload. With increasing preload in SHF the left ventricle dimensions will increase in both systole and diastole. The heart will appear more spherical in shape with thinner walls. The other hallmark feature of SHF is decreased ejection fraction where stroke volume is still maintained as the heart has compensated by dilating the left ventricle. In reality, SHF echo diagnosis is a lot more complex than this as there is valvular diseases, concomitant diastolic failure, anatomic variation and what not.
We estimate preload by diastolic measuring of for example the left ventricular end-diastolic dimension (LVEDD), by measuring the end-diastolic area of the ventricle (EDA) or by letting the US-machine do the maths using the Simpson biplane method. We then move on to measure the corresponding systolic counterparts of these measurements in order to calculate the ejection fraction. If ventricle dimensions are increased, if EF is normal or low and if it patient looks about right then it is SHF.
E-point septal separation
E-point septal separation (EPSS) is the distance from the anterior mitral valve leafleft and the ventricular septum in early diastole.
The measurement is made in m-mode and is simply the closest the mitral valve gets to the septum in the cardiac cycle. In early diastole, the anterior mitral valve should approach or even touch the septum. In SHF, the ballooning heart with increased preload will pull valve away from the septum.
Like the LVEDD, the EPSS is a simple linear m-mode measurement obtained from the parasternal long axis view. As such is easy to obtain, very fast but prone to the same inaccuracies as any single linear measurement, local wall abnormalities and sloppy view angles.
The authors enrolled eighty adult subjects were the treating physician had requested a transthoracic echo, regardless of the indication. Three emergency ultrasound fellows first made a visual estimate of the EF, then measured the EPSS and finally compared their estimates to a gold standard comprehensive cardiac ultrasound performed by cardiac ultrasonographers who estimated EF by using the Teicholz method.
The EPSS measurements are plotted against the gold standard EF in the scattergram. The authors conclude there is a ‘strong correlation’ between increasing EPSS and decreasing EF from comprehensive TTE. The regression formula is in the scattergram.
In contrast, ‘eyeballing’ was not as accurate and interobserver agreement was not as good as EPSS nor as good as reported in previous studies.
Previous literature has recommended a cut-off EPSS of 7 mm to determine severe left ventricular dysfunction. (EF < 30%). In this study 7 mm would be 100% sensitive for EF <30%.
Could be useful. Quick, easy to learn and relies only on a single parasternal view. Like all volumetric echocardiographic assessments it should be interpreted very cautiously. There’s also a lot more to cardiac failure and cardiogenic shock than EF. As always, the more extreme our measurements are, the more we can trust them. (And the less we need them…)
Paper lives here:
E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. McKaigney CJ, Krantz MJ, La Rocque CL, Hurst ND, Buchanan MS, Kendall JL. Am J Emerg Med. 2014 Jun;32(6):493-7. doi: 10.1016/j.ajem.2014.01.045. Epub 2014 Feb 3.