Left ventricle wall thickness

The objective of this chapter is to determine if the left ventricle walls are normal or hypertrophic.

Contents

Measurement of left ventricle walls thickness

You will measure the left ventricle walls thickness in parasternal long axis, at end-diastole, at the same time than you are measuring the left ventricle end-diastolic diameter (LVED).

You must be careful to exclude:

-chordae and papillary muscle from the left ventricle cavity

-moderator bands from the right ventricle cavity

M-mode allows you a higher frame rate with a better delineation between the different structures. This modality is very useful when the limits of the walls are difficult to distinguish from intra-ventricular structures.

You can recognize the inner limit of the posterior wall: it the the line with the steepest slope in systole.

Normal values for walls thickness:

 Normal Mild hypertrophy Moderate hypertrophy Severe hypertrophy Inter-ventricular septum and posterior wall thickness (mm) 6-10 11-13 14-16 >17

Determination of LV mass

The calculation of the LV mass is the most accurate way to determine the presence or absence of LV hypertrophy.

It is recommended to correlate the LV mass to the patient's height and/or body surface area.

LV mass = 0.8 x (1.04 x ((LVIDd + PWTd + SWTd)3 - (LVIDd)3)) = 0.6 g

LVIDd: left ventricle internal diameter, diastole

PWTd: posterior wall thickness, diastole

SWTd: septum wall thickness, diastole

Normal values for left ventricle mass

Men

 Normal Mild LVH Moderate LVH Severe LVH LV mass (g) 67-162 163-186 187-210 >211 LV mass/ BSA (g/m2) 43-95 96-108 109-121 >122 LV mass/ height (g/m) 41-99 100-115 116-128 >129 LV mass/ height2.7 (g/m2.7) 18-44 45-51 52-58 >59

Women

 Normal Mild LVH Moderate LVH Severe LVH LV mass (g) 88-224 225-258 259-292 >293 LV mass/ BSA (g/m2) 49-115 116-131 132-148 >149 LV mass/ height (g/m) 52-126 127-144 125-162 >163 LV mass/ height2.7 (g/m2.7) 20-48 49-55 56-63 >64

Systolic anterior motion of the mitral valve (SAM)

SAM (systolic anterior motion of the mitral valve) is a dynamic left ventricular outflow obstruction caused by an abnormal geometry of the papillary muscles and mitral apparatus combined with hyperdynamic left ventricular function. Varying portions of the mitral apparatus are anteriorly displaced and come in contact with the interventricular septum during systole, creating LV outflow obstruction.

SAM is also frequent in critically ill patients with small LV, mild to moderate LV hypertrophy and in hyperdynamic state (sepsis, volume depletion). The relative collapse of the LV leads to dynamic obstruction of the LV outflow tract and poor hemodynamic tolerance. These patients often need fluid replacement.

SAM can be identified on M-mode or two-dimensional images. Please go to images library for examples of SAM.

References

Lang RM, Bierig M, Devereux RB. Recommendations for chamber quantification. J Am Soc Echocardiogr. 2005 Dec;18(12):1440-63.