Left Ventricular Sphericity Index in Asymptomatic Population

Tissue Doppler, speckling tracking and four-dimensional echocardiographic assessment of right ventricular function in children with dilated cardiomyopathy

BACKGROUND

Right ventricular (RV) function is frequently overlooked during dilated cardiomyopathy (DCM) evaluation.

AIM

To evaluate RV function in children with idiopathic DCM using relatively recent echocardiographic modalities.

METHODS

We prospectively studied the cardiac function in 50 children with idiopathic DCM and 50 healthy children as a control group, using four-dimensional echocardiography (4-DE), Tissue Doppler Imaging (TDI), and two-dimensional-speckles tracking echocardiography (2-D-STE). RV EF was measured by 4-DE.

RESULTS

The auto left (LV) ejection fractions (EF) measured by 2-D-STE were significantly lower in the patients' group than in the control. The sphericity index was also significantly lower in children with DCM than in the control. RV EF measured by 4-DE was significantly lower in the patient's group than the control. RV S wave, e´/a' ratio, myocardial performance index (MPI), and tricuspid annular plane systolic excursion (TAPSE) were significantly impaired in children with DCM than in control. Both LV and RV global longitudinal strains (GLS) were significantly reduced in children with DCM than in control. RVGLS was significantly associated with the duration since diagnosis, tricuspid annulus S wave, RV MPI, and TAPSE, but not with the age of the patients, RV EF, or e´/a' ratio.

CONCLUSION

There was impairment of the RV LGS and other systolic and diastolic parameters in children with DCM. STE and TDI can help to detect the early decline of RV function.

Evaluation of strain averaging area and strain estimation errors in a spheroidal left ventricular model using synthetic image data and speckle tracking

BACKGROUND

In majority of studies on speckle tracking echocardiography (STE) the strain estimates are averaged over large areas of the left ventricle. This may impair the diagnostic capability of the STE in the case of e.g. local changes of the cardiac contractility. This work attempts to evaluate, how far one can reduce the averaging area, without sacrificing the estimation accuracy that could be important from the clinical point of view.

METHODS

Synthetic radio frequency (RF) data of a spheroidal left ventricular (LV) model were generated using FIELD II package and meshes obtained from finite element method (FEM) simulation. The apical two chamber (A2C) view and the mid parasternal short axis view (pSAXM) were simulated. The sector encompassed the entire cross-section (full view) of the LV model or its part (partial view). The wall segments obtained according to the American Heart Association (AHA17) were divided into subsegments of area decreasing down to 3 mm2. Longitudinal, circumferential and radial strain estimates, obtained using a hierarchical block-matching method, were averaged over these subsegments. Estimation accuracy was assessed using several error measures, making most use of the prediction of the maximal relative error of the strain estimate obtained using the FEM derived reference. Three limits of this predicted maximal error were studied, namely 16.7%, 33% and 66%. The smallest averaging area resulting in the strain estimation error below one of these limits was considered the smallest allowable averaging area (SAAA) of the strain estimation.

RESULTS

In all AHA17 segments, using the A2C projection, the SAAA ensuring maximal longitudinal strain estimates error below 33% was below 3 mm2, except for the segment no 17 where it was above 278 mm2. The SAAA ensuring maximal circumferential strain estimates error below 33% depended on the AHA17 segment position within the imaging sector and view type and ranged from below 3-287 mm2. The SAAA ensuring maximal radial strain estimates error below 33% obtained in the pSAXM projection was not less than 287 mm2. The SAAA values obtained using other maximal error limits differ from SAAA values observed for the 33% error limit only in limited number of cases. SAAA decreased when using maximal error limit equal to 66% in these cases. The use of the partial view (narrow sector) resulted in a decrease of the SAAA.

CONCLUSIONS

The SAAA varies strongly between strain components. In a vast part of the LV model wall in the A2C view the longitudinal strain could be estimated using SAAA below 3 mm2, which is smaller than the averaging area currently used in clinic, thus with a higher resolution. The SAAA of the circumferential strain estimation strongly depends on the position of the region of interest and the parameters of the acquisition. The SAAA of the radial strain estimation takes the highest values. The use of a narrow sector could increase diagnostic capabilities of 2D STE.

Relationships between left ventricular geometry and remodeling in dilated cardiomyopathy

BACKGROUND

Since left ventricular reverse remodeling (LVRR) and sphericity index (SI) are correlated with DCM patients' survival, we attempted to establish the relationship between LVRR, SI and left ventricle (LV) dimensions.

METHODS

In 70 DCM patients, we measured EF, LV transverse (sLVd) and longitudinal (lLVd) diameters at hospital admission, then after 3 and 12 months. SI was assessed thus: SI=sLVd/lLVd.

RESULTS

LVRR was present in 32 patients (52%). SI measurements were similar in LVRR-present and -absent groups at baseline (0.71 vs. 0.70) and differed after 3 and 12 months (0.61 vs. 0.72, P<0.005; 0.59 vs. 0.73, P<0.001; respectively). During 12 months, SI and sLVd decreased in the LVRR-present (0.71 vs. 0.61 vs. 0.59, P<0.05; 5.75 vs. 5.00 vs. 4.82 cm, P<0.001; respectively) and increased in the LVRR-absent cohort (0.70 vs. 0.72 vs. 0.73, P<0.001; 6.01 vs. 6.15 vs. 6.67, P<0.001; respectively). lLVd remained stable (8.23 vs. 8.16 vs. 8.38cm; 8.66 vs. 8.85 vs. 9.13 cm; respectively). SI was significantly correlated with sLVd but not with lLVd. At 3-month follow-up, SI (P<0.005, OR=14000 [95% CI: 5 - 3.9*107]) was found to be a significant LVRR predictor via univariate logistic regression.

CONCLUSIONS

To summarize, changes in sLVd are crucial for changes in LV geometry, whereas lLVd has a negligible effect on this process. The presence of LVRR was not always associated with an improvement in SI and its absence with increase in SI. Since the assessment of SI is less complex than LVRR, SI as a significant LVRR predictor can be useful part of a regular echocardiography examination.