**2.1.2 Echocardiographic RV hypokinesis**

Moderate or severe RV free-wall hypokinesis may be accompanied by relatively normal contraction and "sparing" of the RV apex, a phenomenon called the McConnell sign (McConnell et al., 1996). In patients with PE, the McConnell sign had a sensitivity of 77%, a specificity of 94%, a positive predictive value of 71%, and a negative predictive value of 96%. This sign appeared useful in distinguishing between RV dysfunction due to PE and dysfunction due to other conditions, such as primary pulmonary hypertension. For patients with RV hypokinesis due to acute PE, the excursion diminished markedly when measured in the middle of the RV free wall. However, the excursion improved progressively when segments closer to the apex were measured. This pattern of regional RV dysfunction appeared highly specific for acute PE; in patients with RV dysfunction due to primary pulmonary hypertension, RV hypokinesis was not improved when apical segments were assessed.

Risk Stratification of Submassive Pulmonary Embolism:

**3.1.1 RV dilation (RV/LV ratio)** 

The Role of Chest Computed Tomography as an Alternative to Echocardiography 173

Similar to echocardiography, contrast-enhanced CT allows assessment of the right-to-left ventricular ratio. RV and LV diameters are assessed on each single image at the plane of maximal visualization of the ventricular cavities, usually at the mitral valve plane for LV and the tricuspid valve level for RV, between the inner surface endocardial border of the

Fig. 2. Transverse contrast-enhanced CT scan showing maximum minor axis measurements

The RV/LV minor axis ratio is widely accepted as a measure of RV dilatation on CT, however, the cut-off values of RV/LV ratio used for RV dysfunction vary among reports. Ghuysen et al suggested an RV/LV ratio >1.5 indicates a severe episode of PE (Ghuysen et al., 2005), Araoz et al suggested an RV/LV ratio >1 was associated with a 3.6-fold increased risk of admission to the intensive care unit (Araoz et al., 2003), and in another study, the same threshold was shown to be a significant risk factor for mortality within 3 months, with an RV/LV ratio ≤1.0 having a PPV of 10.1% (95% CI: 2.9%, 17.4%) and an NPV of 100% (95% CI: 94.3%, 100%) for an uneventful outcome (van der Meer et al., 2005). An RV/LV ratio >0.9 on reconstructed CT four-chamber views has been associated with a poorer prognosis in patients with PE (Schoepf et al., 2004), with an NPV of 92.3% and a PPV of 15.6% for 30-day mortality, and a hazard ratio for predicting 30-day mortality of 5.17 (95% CI, 1.63 – 16.35;

Concerns have arisen regarding whether non-gated CT may be inaccurate in measuring ventricular chamber size because the images are acquired in different phases of the cardiac cycle. However ECG-gated CT scan is not always available, and is time-consuming. Thus, a ECG-gated CT scan is impractical in an emergency situation. In addition, recent findings

**3.1 Computed tomography findings of right ventricular dysfunction** 

free wall and the surface of the interventricular septum (Fig. 2).

of the right ventricle (A) and left ventricle (B). RV/LV ratio = 2

P=0.005).

RV: right ventricle; LV: left ventricle; Ao: aorta; LA: left atrium

Fig. 1. Echocardiographic findings of pulmonary embolism in the parasternal long-axis (A) and short-axis (B) views.


Table 1. Abnormal echocardiographic findings in patients with pulmonary embolism
