Role of strain imaging in right heart disease: a comprehensive review

Right atrial mechanics provide useful insight in pediatric pulmonary hypertension

Right atrial (RA) mechanics have been studied infrequently in children in the past due to technical constraints. With the advent of strain imaging, RA physiology can now be studied in greater detail. The principal aim of this study was to describe functional changes in right heart mechanics of children with idiopathic pulmonary arterial hypertension (PAH), by using new applications of RA strain. In this retrospective study, we evaluated RA mechanics of 20 patients (age range = 3-23 years) with PAH and 18 control patients. RA longitudinal strain (RALS) and longitudinal displacement (LD) were calculated by speckle-tracking echocardiography. RALS was plotted against LD, producing a characteristic strain-displacement (S-D) loop. Standard indices of right heart function and right heart catheterization data were obtained. Patients were clinically subdivided into "compensated" and "decompensated" PAH. A chart review was performed to identify patients who subsequently developed adverse outcomes, including death, awaiting or received lung and/or heart transplantation. RALS was significantly lower in decompensated PAH compared with both controls and compensated PAH. Area enclosed by S-D loops differed significantly between the compensated and decompensated PAH subgroups (5.33 [3.90-9.44] versus 1.83 [1.17-2.36], P < 0.05). S-D loop area and RALS possessed high sensitivity and specificity compared to other parameters for identifying children with PAH who subsequently developed adverse outcomes. In particular, their sensitivities and specificities were greatly superior compared to those of tricuspid annular plane systolic excursion (TAPSE). RALS may represent a useful metric for assessing right ventricular (RV) dysfunction. S-D loops, composed over an entire cardiac cycle, may present useful, composite information regarding both systolic and diastolic right heart function. RA mechanics may serve as useful tools for identifying patients with more severe PAH, who are at risk for future adverse outcomes associated with RV failure.

Echocardiographic Assessment of the Right Ventricle, from the Conventional Approach to Speckle Tracking and Three-Dimensional Imaging, and Insights into the "Right Way" to Explore the Forgotten Chamber

BACKGROUND

The right ventricle (RV) has an essential function in cardiovascular physiology and pathology. Currently, it is gaining an increasing interest given its recognized role in many cardiovascular conditions. However, echocardiographic assessment of the RV in daily practice is frequently based on qualitative estimation, and it has been regarded as a neglected chamber.

OBJECTIVE

We sought to review and discuss the appropriate approach and latest methods of assessment of the RV by echocardiography.

METHODS

A MEDLINE/Pubmed search was performed, and 55 relevant articles were selected; articles addressing right ventricular assessment by echocardiography, along with the latest recommendations, have been reviewed and discussed.

RESULTS

A RV diameter >42 mm at the base and >35 mm at the mid-cavitary level indicates right ventricular dilatation; a longitudinal myocardial velocity (S') <9.5 mm/s, a tricuspid annular plane systolic excursion <17 mm, and a fractional area change <35% are indices of right ventricular systolic dysfunction. A right ventricular ejection fraction of >45% and an absolute value of global longitudinal strain of >21% reflect normal systolic function. The significance of dp/dt, the right myocardial performance index and isovolumic myocardial acceleration, is also discussed along with the parameters of right ventricular diastolic function. The use of novel echocardiographic approaches, such as three-dimensional echo and speckle tracking imaging, allows practitioners to overcome the challenges encountered with conventional echocardiography.

CONCLUSION

Accurate assessment of the RV by echocardiography yields early detection of cardiac diseases, enhances risk stratification, and allows timely initiation of appropriate therapy.