Frame rate required for speckle tracking echocardiography: A quantitative clinical study with open-source, vendor-independent software

The mechanics of congenital heart disease: from a morphological trait to the functional echocardiographic evaluation

Advances in pediatric cardiac surgery have resulted in a recent growing epidemic of children and young adults with congenital heart diseases (CHDs). In these patients, congenital defects themselves, surgical operations and remaining lesions may alter cardiac anatomy and impact the mechanical performance of both ventricles. Cardiac function significantly influences outcomes in CHDs, necessitating regular patient follow-up to detect clinical changes and relevant risk factors. Echocardiography remains the primary imaging method for CHDs, but clinicians must understand patients' unique anatomies as different CHDs exhibit distinct anatomical characteristics affecting cardiac mechanics. Additionally, the use of myocardial deformation imaging and 3D echocardiography has gained popularity for enhanced assessment of cardiac function and anatomy. This paper discusses the role of echocardiography in evaluating cardiac mechanics in most significant CHDs, particularly its ability to accommodate and interpret the inherent anatomical substrate in these conditions.

Cardiac cine CT approaching 1 mSv: implementation and assessment of a 58-ms temporal resolution protocol

Clinical use of cardiac cine CT imaging is limited by high radiation dose and low temporal resolution. To evaluate a low radiation dose, high temporal resolution cardiac cine CT protocol in human cardiac CT and phantom scans. CT scans of a circulating iodine target were reconstructed using the conventional single heartbeat half-scan (HS, approx. 175 ms temporal resolution) and the 3-heartbeat multi-segment (MS, approx. 58 ms) algorithms. Motion artifacts were quantified by the root-mean-square error (RMSE). Low-dose cardiac cine CT scans were performed in 55 subjects at a tube potential of 80 kVp and current of 80 mA. Image quality of HS and MS scans was assessed by blinded reader quality assessment, left ventricular (LV) free wall motion, and LV ejection rate. Motion artifacts in phantom scans were higher in HS than in MS reconstructions (RSME 188 and 117 HU, respectively; p = 0.001). Median radiation dose in human scans was 1.2 mSv. LV late diastolic filling was observed more frequently in MS than in HS images (42 vs. 26 subjects, respectively; p < 0.001). LV free wall systolic motion was more physiologic and had less error in MS than in HS reconstructions (sum-of-squared errors 34 vs. 45 mm², respectively; p < 0.001), and LV peak ejection rate was higher in MS than in HS reconstructions (166 vs. 152 mL/s, respectively; p < 0.001). Cardiac cine CT imaging is feasible at a low radiation dose of 1.2 mSv. MS reconstruction showed improved imaging of rapid motion in phantom studies and human cardiac CTs.

Cardiac Function in Infants Born to Mothers With Gestational Diabetes - Estimation of Early Diastolic Intraventricular Pressure Differences

Background: This study compared the myocardial performance of infants born to mothers with gestational diabetes mellitus (IGDM) and without GDM (controls) under the new GDM definitions.

Methods and Results: The subjects consisted of 36 IGDM and 39 control infants. GDM diagnosis was based on oral glucose tolerance test during pregnancy or the presence of diabetes prior to the current pregnancy. Between-group infant cardiac function was determined and compared using 2-D speckle tracking analysis, intraventricular pressure difference (IVPD) and IVP gradient (IVPG), using color M-mode Doppler imaging. IVPD and IVPG were higher in IGDM than in the controls, particularly the mid–apical IVPG. The global circumferential strain (GCS) and endocardial GCS were higher in IGDM than in controls. Increased maternal glycated hemoglobin was correlated with reduced transmural and epicardial GCS in the IGDM. Maternal maximum fasting blood sugar had a mild, positive correlation with IVPD and IVPG.

Conclusions: Ventricular sucking force, measured as the IVPD, IVPG, and endocardial GCS, were higher in IGDM than in the controls. A hyperglycemic environment during pregnancy leads to impaired cardiac performance in IGDM, compared with control infants. IGDM might have favorable systolic and diastolic cardiac performance due to cardiac metabolic adaptations occurring before poor glucose control causes impaired cardiac performance.

A method for determining local pulse wave velocity in human ascending aorta from sequential ultrasound measurements of diameter and velocity

BACKGROUND

Pulse wave velocity (PWV) is an indicator of arterial stiffness, and predicts cardiovascular events independently of blood pressure. Currently, PWV is commonly measured by the foot-to-foot technique thus giving a global estimate of large arterial stiffness. However, and despite its importance, methods to measure the stiffness of the ascending aorta are limited.

OBJECTIVE

To introduce a method for calculating local PWV in the human ascending aorta using non-invasive ultrasound measurements of its diameter (D) and flow velocity (U).

APPROACH

Ten participants (four females) were recruited from Brunel University students. Ascending aortic diameter and velocity were recorded with a GE Vivid E95 equipped with a 1.5-4.5 MHz phased array transducer using M-mode in the parasternal long axis view and pulse wave Doppler in the apical five chamber view respectively. Groups of six consecutive heartbeats were selected from each 20 s run based on the most similar cycle length resulting in three groups for D and three for U each with six waveforms. Each D waveform was paired with each U waveform to calculate PWV using ln(D)U-loop method.

MAIN RESULTS

The diastolic portions of the diameters or velocities waveforms were truncated to allow the pairs to have equal length and were used to construct ln(D)U-loops. The trimmed average, excluding 10% of extreme values, resulting from the 324 loops was considered representative for each participant. Overall mean local PWV for all participants was 4.1(SD  =  0.9) m s-1.

SIGNIFICANCE

Local PWV can be measured non-invasively in the ascending aorta using ultrasound measurements of diameter and flow velocity This should facilitate more widespread assessment of ascending aortic stiffness in larger studies.

Comprehensive echocardiographic assessment of biventricular function in the rabbit, animal model in cardiovascular research: feasibility and normal values

Quantification of cardiac structure and function is central in cardiovascular research. Rabbits are valuable research models of cardiovascular human disease; however, there is little normal data available. The aim of this study was to investigate feasibility and provide normal values for comprehensive echocardiographic assessment of biventricular function in rabbits. New Zealand white rabbits underwent trans-thoracic echocardiography using a general electric (GE) Vivid 7/E9 system with a 10 MHz transducer, under light sedation, to evaluate biventricular function and dimensions. Images for two-dimensional, M-mode, tissue Doppler imaging (TDI) and speckle-tracking strain echocardiography were acquired and analysed. 55 male rabbits (sized matched with a newborn human baby) were studied, mean weight was 2.9 ± 0.23 kg. Adequate images were obtained in 90% for the left ventricle (LV) and 80% for the right ventricle (RV). Two-dimensional speckle-tracking strain was feasible in 60%. Average heart rate was 248 ± 36 beats per minute; LV ejection faction 72 ± 8.0; RV fractional area change 45.9 ± 9.0%; RV myocardial performance index 0.39 ± 0.35; tricuspid annular planar systolic excursion 0.60 ± 0.24 cm. LV TDI parameters were S' 8.6 ± 3.1 cm/s; E' 12.0 ± 4.46 cm/s. RV TDI parameters were S' 10.49 ± 3.18; E' 14.95 ± 4.64 cm/s. LV and RV global peak systolic longitudinal strain were -17 ± 5 and -22 ± 8%, respectively. Comprehensive investigation of biventricular dimensions and function by echocardiography is feasible in the rabbit. Apical views and strain imaging have lower feasibility. Normal values of LV and RV functional parameters are with comparable values to human children. Animal cardiovascular research is key to develop new goals in clinical practice.

Automatic detection of end-diastolic and end-systolic frames in 2D echocardiography

BACKGROUND

Correctly selecting the end-diastolic and end-systolic frames on a 2D echocardiogram is important and challenging, for both human experts and automated algorithms. Manual selection is time-consuming and subject to uncertainty, and may affect the results obtained, especially for advanced measurements such as myocardial strain.

METHODS AND RESULTS

We developed and evaluated algorithms which can automatically extract global and regional cardiac velocity, and identify end-diastolic and end-systolic frames. We acquired apical four-chamber 2D echocardiographic video recordings, each at least 10 heartbeats long, acquired twice at frame rates of 52 and 79 frames/s from 19 patients, yielding 38 recordings. Five experienced echocardiographers independently marked end-systolic and end-diastolic frames for the first 10 heartbeats of each recording. The automated algorithm also did this. Using the average of time points identified by five human operators as the reference gold standard, the individual operators had a root mean square difference from that gold standard of 46.5 ms. The algorithm had a root mean square difference from the human gold standard of 40.5 ms (P<.0001). Put another way, the algorithm-identified time point was an outlier in 122/564 heartbeats (21.6%), whereas the average human operator was an outlier in 254/564 heartbeats (45%).

CONCLUSION

An automated algorithm can identify the end-systolic and end-diastolic frames with performance indistinguishable from that of human experts. This saves staff time, which could therefore be invested in assessing more beats, and reduces uncertainty about the reliability of the choice of frame.