04. Diastolic overload

Diastolic overload of the right ventricle dilates this chamber at the end of diastole. This dilatation is easy to observe but difficult to measure accurately. The particular shape of the right ventricle means that any volume calculation by echocardiography is impossible in practice. However, long-axis measurement of the right ventricular area is straightforward using an apical four-chamber view or the transesophageal route. It is therefore possible to establish the ratio of the end-diastolic areas of the two ventricles, which is normally less than or equal to 0.6. A ratio above 0.6 can therefore be considered as indicative of right ventricular dilatation. But this is not necessarily pathological and must be interpreted in the light of other echocardiographic signs, notably the presence or absence of a septal anomaly suggesting systolic overload. Likewise, a normal Doppler echocardiogram of mitral flow, when the RV seems slightly dilated, rules out a pathological cause. On the other hand, a E/A ratio equal to or lower than one indicates marked right ventricular dilatation and is always pathological.

 

The right ventricular dilatation observed during acute cor pulmonale is associated with right atrial dilatation  (Figure 2, Figure 10), and enlargement of the inferior vena cava.
 

There is also tricuspid regurgitation which can be seen by contrast ultrasound (Figure 11),  and which is utilized to measure pulmonary artery systolic pressure, using Doppler echocardiography (Figure 3).When right atrial pressure exceeds left atrial pressure, the foramen ovale, which had remained permeable, may reopen. This anomaly, which induces a right-left shunt, can be detected by contrast ultrasound or color Doppler (Figure 13) (5, 6). It causes paradoxical arterial embolism in thromboembolic disease (7).

 Film 9 : ETO chez une patiente sous ventilation contrôlée pour un SDRA secondaire à une inhalation massive. Après plusieurs jours de ventilation, la patiente développe un CPA. L’ETO objective la présence d’un foramen ovale perméable (flux orangé), grâce au Doppler couleur, en utilisant l’image bidimensionnelle (à droite) couplé au mode temps-mouvement (à gauche).