At the End of Starling's Curve

A female in her 70s with a background of Heart Failure presented to ED as a blue call with severe shortness of breath and hypoxia. Her vitals were: HR 122, BP 175/101, T36.2, SATs 84% on 15NRM, RR 35. On examination she was in severe respiratory distress and had a clearly elevated JVP, pitting oedema to the knees and on auscultation widespread crackles in both lung fields. She did not complain of chest pain. To differnetiate causes for her respiratory distress a bedside ECHO was done upon arrival whilst waiting for a portable chest xray to be done.

A phased array cardiac probe was placed in both both lung fields showing diffuse B-lines extending throughout the scan. In the context of the patient, this gave rise to a clinical suspicion of pulmonary oedema. If the patient's respiratory distress and hypoxia was from acute pulmonary oedema, we should expect to see reduced left ventricular contractility.

On a Parasternal Long Axis view, the M-mode line was placed on the tip of the free moving anterior Mitral valve leaflet. This image shows the calculation of the EPSS: E-point Septal Separation - a classic ECHO measure of LV systolic function. The red line measures the distance between the E-point of the Mitral valve anterior leaflet (tip of the triangle) to the interventricular septum. In a healthy heart, there is good Mitral valve motility in a normally contractile LV - this gives rise to an EPSS measurement of <7mm. In a failing heart with reduced LV contractility, the EPSS will widen >10mm. Here it is 12.7mm and consistent with the clinical picture of worsened LV failure and reduced contractility giving rise to acutely worsened pulmonary oedema.

Common pitfalls

EPSS may be falsely increased in:

• Aortic regurgitation (high LV filling volume)

• Mitral stenosis or abnormal valve motion

• Dilated cardiomyopathy (valid but nonspecific)

• Poor image alignment (M-mode not through leaflet tip)

Clinical pearl

EPSS is:

• Quick bedside surrogate for LV Ejection Fraction

• Useful in emergency ECHO

• Not a replacement for Simpson’s biplane EF

To further consolidate this clinical inference of acutely worsened LV failure giving rise to pulmonary oedema, on the same PLAX view M-mode is placed accross the widest portion of the LV. In cross section we can now see the LV in systole (red line) and diastole (blue). By measuring these 2 dimensions and diving them, we can obtain an estimate of the LV ejection fraction (Fractional Decrease method of Ejection Fraction). Here it is falling between 35-40%. This is consistent with acute LV failure.

The chest xray was consistent with the ECHO findings showing cardiomegaly and upper lobe diversion with pulmonary oedema. The working diagnosis of acute pulmonary oedema in heart failure was made and the patient was treated with Furosemide, a GTN infusion and required CPAP to improve oxygenation. Her management was continued by the Medical Team and ITU.

Summary of Key Points:

• When suspecting cardiac failure, a bedside ECHO can be used inconjunction with well known clinical signs of overload to diagnose acute cardiac failure. 

• Qualitative observations of acute cardiac failure on ECHO can include a wide non collapsing IVC > 2.5cm, hypokinetic and dilated ventricles. A more advanced approach is to provide a quantitative assessment using the EPSS method and the Fractional Decrease estimate of LV Ejection Fraction. The gold standard measurement done by Cardiologists is the Simpson's Biplane EV calculation done in the Apical 4-Chamber view.

Trainee Lead Editor: Dr Amy Knowles, ST5

Checked: Dr Ahmed Abdul-Ghani, Lead Project Consultant