Ventricular dilatation

The study of the left ventricle (LV) in M-mode echocardiography requires a high level of recording quality in order to obtain reliable and reproducible results. The causes of errors in the measurement of the internal diameters of the LV using M-mode are:

The end-diastole is generally identified as the beginning of the Q wave (American Society of Echocardiography (ASE) technique) or the peak of the R wave of the QRS complex (Pennsylvania (PENN) technique).

At end-systole, the measurements are made using one of two methods:

The internal diameters of the LV are measured according to the approriate convention (Fig. 8.1, and see Fig. 7.1).

Figure 8.1 Measurement of the internal diameters of the left ventricle (LV) in 2D M-mode. (a) Correct M-mode projection perpendicular to the ventricular walls. (b) Variations in the diastolic diameter during continuous arrhythmia. (c) Overestimation of the diastolic diameter in the presence of a septal kink, and (d) the corrected diameter obtained using a less oblique projection. AO, aorta; LA, left atrium; RV, right ventricle.

Nevertheless, the measurement of the end-systolic diameter of the LV (and thus of the left ventricuar end-systolic surface area (LVSA)) should be abandoned (and consequently also the calculation of the shortening fraction) in the case of paradoxical septal motion.

The normal values of the ventricular diameters in adults are summarized in Table 8.1. However, it is strongly recommended that the patient’s size be taken into account in order to interpret the end-diastolic diameter (EDD) of the LV, in particular. A correction of the EDD values for the body surface area is recommended. In practice, the threshold values of 56 mm (absolute values) or 32 mm/m² (as a function of the body surface area) are more often used for EDD. Values above these thresholds confirm dilatation of the LV. However, the dilatation may be non-homogeneous, e.g. an aneurysmal dilatation involving only the apical region of the LV (Fig. 8.2). In fact, the EDD measured classically using M-mode corresponds to the internal diameter of the basal region of the LV only. A precise two-dimensional (2D) study of the size of the LV is therefore necessary in order to avoid diagnostic errors due to localized ventricular dilatations.

Table 8.1 Normal values in adults of the end-diastolic and end-systolic diameters, and the end-diastolic and end-systolic surfaces of the left ventricle (LV) in transthoracic echocardiography (TTE)

Figure 8.2 Non-homogeneous dilatation of the left ventricle (LV): voluminous aneurysm (AN) of the septoapical region of an infarcted LV (arrows). LA, left atrium; RA, right atrium; RV, right ventricle.

The optimum visualization of the internal contours of the LV, in the apical four-chamber projection, makes it possible to measure the left ventricular end-diastolic surface area (LVDA) and left ventricular end-systolic surface area (LVSA) using the planimetry technique (normal values are summarized in Table 8.1). However, these measures, which deliberately exclude the papillary muscles, are rarely used as a matter of routine, due to their relatively low reliability and reproducibility.

Echocardiographic measurement of the right ventricle (RV) is difficult, due to the complex form of the RV, wrapped around the LV. In practice, the internal diameter of the RV is measured at end-diastole, using M-mode echocardiography in the parasternal, long-axis view. The norm in adults examined in the dorsal decubitus is on average 13.6 ± 2.6 mm, with values ranging between 7 mm and 23 mm. In the left lateral decubitus, the diameter of the normal RV is slightly increased (9–26 mm). Moreover, the diameter of the RV may vary in a physiological manner with respiration (an increase on inspiration of 2–3 mm). Due to the high individual variability of the right ventricular diameter, it is preferable to use the ratio of the left and right ventricular diameters during diastole (RV/LV), which is normally around 0.33.

The diameters of the LV and RV may also be measured using 2D echocardiography (Fig. 8.3).

Figure 8.3 Normal values in adults for the left and right ventricular diameters in transthoracic 2D echocardiography. Measurements carried out according to the four-chamber projection during diastole and systole. AO, aorta; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

Dilatation of the atria

Echocardiography can be used to evaluate the diameters and the surface area of the left atrium (LA). The anteroposterior diameter of the LA is routinely measured in M-mode using the parasternal, long-axis view during end-diastole (Fig. 8.4). This is a simple measurement, and its accuracy is usually good. The potential limitations concerning the measurement of the anteroposterior diameter of the LA are:

Figure 8.4 Measurements of the left atrium: (a) in M-mode echocardiography, anteroposterior diameter (D₁); (b) in 2D echocardiography, apical four-chamber view, superoinferior diameter (D₂), surface area (S) measured by planimetry. An, plane of mitral annulus; AO, aorta; LA, left atrium; LPV, left pulmonary vein; LV, left ventricle; RA, right atrium; RPV, right pulmonary vein.

Figure 8.5 Measurement of the anteroposterior diameter of the left atrium (LA) using M-mode in the parasternal, long-axis projection. (a) Correct measurement, made perpendicular to the walls.(b) Oblique M-mode projection, increasing the measured diameter of the LA to 61 mm (actual diameter in 2D is 51 mm). AO, aorta; LV, left ventricle; RV, right ventricle.

In fact, measuring only the anteroposterior diameter in the long-axis projection is insufficient in the case of asymmetrical enlargement or non-homogeneous dilatation of the LA, which is frequently observed in older patients. In these situations, it is recommended that the superoinferior diameter of the LA is also measured. This diameter is measured using the 2D mode (apical cross-section of the four chambers) from the plane of the mitral annulus to the base of the LA, during systole (Figs 8.4 and 8.6). The normal values for these two atrial diameters as measured using echocardiography are summarized in Table 8.2.

Figure 8.6 Non-homogeneous dilatation of the left atrium (LA). (a) Normal anteroseptal diameter (38 mm), increased superoinferior diameter (59 mm). Surface area of the LA measured using planimetry = 20 cm². (b) Ectasic dilatation of the LA: anteroposterior diameter = 63 mm, superoinferior diameter = 71 mm; surface area measured using planimetry = 41 cm². LV, left ventricle; RA, right atrium; RV, right ventricle.

Stay updated, free articles. Join our Telegram channel

Join