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Wednesday, February 15, 2023

What does "impaired relaxation" on echo report mean and what to do about it

Half of the patients labelled as having  heart failure are designated as "diastolic heart failure" or HFpEF,  the currently prefered medical jargon for heart failure with preserved ejection fraction. The other half of HF patients have heart failure with reduced ejection fraction or HFrEF.

Both categories are creatures of the echocardiogram.The ejection fraction or EF is the ratio of the stroke volume to the volume of blood in the left ventricle at the end of diastole.Diastolic dysfunction is defined by various combinations of other echo measurements, that relate to how easily blood flows into the left ventricle during the ventricular filling phase aka diastole and strive to be clinically useful indicators of an elevated left ventricular filling pressure (EDLVP)

It seems to be the case that as humans age the blood flow less easily into the left ventricle due to a number of related and as always in medicine or biology poorly understood factors.These include the capacity of the ventricle to relax after ejecting the blood in systole,how stiff or compliant the ventricle is,the geometry of the ventricle, how well " restoring forces"  (aka elastic  recoil) - THINK HERE OF COmPRESSING A TENNIS BALL AND THEN RELEASING THEFORCE AND BALL POPS BACK IN SHAPEwork and the restraint of the pericardium.The key distinguishing characteristic of an elite endurance athlete is impressive diastolic filling.

Ventricular  diastole flow is typically considered to have two phases-the early rapid filling phase and the later phase brought about the contraction of the atria.These stages can be visualized and quantitated by placing an echo probe of the the mitral valve and measuring the velocity of early flow  (the E wave) and the late wave (the A wave) and if we have two numbers someone will make a ratio.

The ratio of the early velocity to the late velocity ( E/A ratio) is a simple measure of diastolic function.With aging early flow decreases (  generally thought to be due  in early diastole to impaired relaxation and loss of elastic recoil) resulting in a lower E/A ratio. This is considered to be the earliest stage of diastolic dysfunction in which diastolic flow is decreased but cardiac filling pressures have not significantly increased. As ventricular filling become more impaired pressure builds in the left ratrium so that early flow increases as does the E/A  restoring a normal appearing a pattern labelled as "pseudonormal" ( this stage is now referred to as "stage one " in the 2016  American Society of Echocadiography and the older terms for the more severe stages of diastolic function,pseudonormal and restrictive have also been replaced with stage 2 and stage 3.)

Not only can diastolic flow across the mitral valve be measured by echo so can the movement of the supporting tissue of the mitral valve ( mitral annulus). The early movement , coincident with the E wave is labelled e prime and the late movement a prime.
But what to about echo reports that state impaired relaxation.Is it "normal for age" or a possible percursor to HFpEF.is there any role for aerobic exercise to lessen progression to HFpEF?

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