Real-time three-dimensional echocardiography to construct clinically ready, load-independent indices of myocardial contractile performance

Combination of real time three-dimensional echocardiography with diagnostic catheterization to derive left ventricular pressure-volume relations

AIMS

The aim of this study was to investigate the left ventricular (LV) myocardial contractility index-Emax using transesophageal real time three-dimensional echocardiography (RT3DE) combined with catheterization.

METHODS

Transesophageal RT3DE (single beat, X7-2 × matrix, iE33, Philips) was used to obtain real time LV volumes in pigs. Volumes were integrated with LV pressures from conductance catheterization (CC) to create RT3DE pressure-volume relations. At the same time, CC was used for measuring conventional pressure-volume relations that served as reference. The slope Emax was determined from RT3DE and CC end-systolic pressure-volume relations. All measurements were made at rest and during dobutamine infusion.

RESULTS

In six pigs, the mean ± SD (mmHg/mL) values were Emax-CC 1.86 ± 1.1 and Emax-RT3DE 1.78 ± 1.2 (P = 0.502) at baseline. On dobutamine, mean Emax-CC was 3.43 ± 1.5 and Emax-RT3DE 3.60 ± 1.23 (P = 0.171). Bland-Altman analysis showed good agreements between the RT3DE- and CC-derived Emax for measurements performed at baseline and on dobutamine.

CONCLUSIONS

Emax can be determined from RT3DE integrated with catheterization-derived pressures. RT3DE is a promising method for enhancing clinical applicability of pressure-volume relations for assessment of myocardial contractility.

Feasibility and initial experience of assessment of mechanical dyssynchrony using cardiovascular magnetic resonance and semi-automatic border detection

BACKGROUND

The systolic dyssynchrony index (SDI) has been introduced as a measure of mechanical dyssynchrony using three-dimensional echocardiography to select patients who may benefit from cardiac resynchronization therapy (CRT). However, three-dimensional echocardiography may be inadequate in a number of patients with suboptimal acoustic window and no single echocardiographic measure of dyssynchrony has proven to be of value in selecting patients for CRT. Thus, the aim of this study was to determine the value of cardiovascular magnetic resonance (CMR) for the assessment of the SDI in patients with reduced LV function as well as in healthy controls using semi-automatic border tracking.

METHODS

We investigated a total of 45 patients including 35 patients (65 +/- 8 years) with reduced LV function (EF 30 +/- 11%) and a wide QRS complex as well as 10 control subjects (42 +/- 21 years, EF 70 +/- 11%). For cine imaging a standard SSFP imaging sequence was used with a temporal resolution of 40 frames per RR-interval. Quantitative analysis was performed off-line using a software prototype for semi-automatic border detection. Global volumes, ejection fraction and the SDI were calculated in each subject. SDI was compared with standard echocardiographic parameters of dyssynchrony.

RESULTS

The mean SDI differed significantly between patients (14 +/- 5%) and controls (5 +/- 2%, p < 0.001). An exponential correlation between the EF and the SDI was observed (r = -0.84; p < 0.001). In addition, a significant association between the SDI and the standard deviation of time to peak systolic motion of 12 LV segments (Ts-SD) determined by echocardiography was observed (r = 0.66, p = 0.002).

CONCLUSION

The results of this preliminary study suggest that CMR with semi-automatic border detection may be useful for the assessment of mechanical dyssynchrony in patients with reduced LV function.

Assessment of left ventricular asynchrony using volume-time curves of 16 segments by real-time 3 dimensional echocardiography: Comparison with tissue Doppler imaging

BACKGROUND

Recent technical developments with high-resolution real-time 3 dimensional echocardiography (RT3DE) facilitate the acquisition of high quality images and the analysis of segmental volume-time curves (VTCs).

AIMS

To assess left ventricular (LV) asynchrony using the VTCs of 16 segments by RT3DE, and to evaluate accuracy compared to tissue Doppler imaging (TDI).

METHODS

Twenty-three heart failure (HF) patients (LVEF: 25+/-6%, age: 60+/-13 years) and 16 normal controls underwent TDI and RT3DE. The standard deviation (SD3) of the end systolic time reaching minimal systolic volume for the 16 segments on VTCs was obtained by RT3DE. The standard deviation (SD2) of the electromechanical coupling time for the 8 segments was measured using TDI.

RESULTS

SD3 was markedly higher in HF patients than in controls (7.7+/-2.5 vs 1.5+/-1.0%, P<0.01) and increased as LVEF decreased (r=-0.85, P<0.01). SD2 was also significantly higher in HF patients (27.0+/-8.6 vs 12.6+/-5.0 ms, P<0.01) and had a good negative correlation with LVEF (r=-0.72, P<0.01). SD3 was well correlated to SD2 (r=0.66, P<0.01).

CONCLUSIONS

We suggest that analysis of VTCs in 16 segments using RT3DE may be a useful alternative to TDI for the evaluation of LV asynchrony.

Live 3D Echocardiography: A Replacement for Traditional 2D Echocardiography?

OBJECTIVE

We describe the development of real-time 3D imaging and review the previously used versions of 3D echocardiography so that the reader will appreciate why current developments truly do represent a quantum leap in the technology.

CONCLUSION

Three-dimensional echocardiography has now been shown to have several advantages over 2D echocardiography, particularly for volume measurements, visualization of septal defects, and whole-valve evaluation. Given these data, it is clear that 3D echocardiography is here to stay and soon will become part of routine echocardiographic examinations.