使用3D超声心动图评估左心室结构和功能

3D echocardiographic assessment of cardiac structure and function, is a breakthrough innovation in cardiology. Quantification of left ventricle morphology and systolic performance, is the single most important step in every echocardiographic protocol. 3D echocardiographic-derived left ventricular volumes and ejection fraction correlate the most with core standard cardiac MRI and have shown to be more reproducible compared with conventional 2D techniques.

More accurate results, turn into more tailored therapeutic decisions and that the end of the day, better patient outcomes. The scientific and clinical success of 3D based left ventricle assessment, paves the way to apply a similar technique to other cardiac structures such as right ventricle, the atria or even the valves. Proper image acquisition, followed by a comprehensive critical image analysis are the prerequisites for adequate use and accurate measurements.

Our video article provides a step-by-step guide to achieve this. For the acquisition of 3D echocardiographic images, position the patient in the left lateral decubitus position and confirm that the ECG tracing on the screen is of good quality. Unfreeze the image and begin to examine the patient with the transducer, to visualize as a conventional apical four chamber view.

To optimize the image quality, adjust the sector width to the left ventricle, lowering the depth to truncate the left atrium and using a slight over gain. Press the 4D button to switch to 3D mode and acquire 3D images in the multi or single-beat mode. Use the multi-beat mode to achieve a higher spatial and temporal resolution, from which the dataset will be reconstructed from two, three, four or six cardiac cycles.

Obtain an end expiratory breath hold of the patient, maintaining the stable transducer positioning, to minimize the stitching artifacts. When the full volume is reconstructed from the sub-volumes and entire left ventricle is visible, freeze the image again. And using the cycle select and number of cycles knobs, select the optimal acquired cardiac cycles and press image store.

For left ventricle morphology and function quantification, select a 3D data set appropriate for analysis and click measure and volume. Select 4D Auto LVQ. On the quad screen, the software will ask, modify alignment of apical slices to standard views?

Correct the apical views manually as necessary by tilting and rotation, to obtain the corresponding standard view and thereby eliminating foreshortening. Drag and move the calipers on the long axis views to set the tilting to align the caliper with the long axis of the left ventricle and use the corresponding or rotate all knobs or adjust the calipers on the short axis image to set the rotation. After finishing the view alignment, click to the end-diastolic volume.

For semiautomatic detection of the left ventricle endo and epicardial surface, select two landmark points manually on any apical views and successively identify the left ventricle apex and the middle of the left ventricle base in any apical view. The algorithm will automatically contour the endocardial border of the entire left ventricle. Check contour credibility in three apical views, three short axis views of different levels and a fourth user controlled short axis, to allow visual verification of the detected surface.

Then proceed to and measure the end-systolic volume as just demonstrated for the end-diastolic volume, to identify and correct the endocardial contour on the end-systolic frame. Next, proceed to volume wave form. The software will display a dynamic 3D model of the left ventricle and a time volume curve as it traces the endocardial surface throughout the cardiac cycle frame by frame.

Proceed to the left ventricle mass measurement. The software will automatically contour the left ventricle epicardial contour on the end-diastolic frame, and calculate the left ventricle mass. Click to assess the 4D strain region of interest.

The software will automatically contour epicardial surface on the end-systolic frame, and calculate the left ventricle and systolic mass. Finally, click 4D strain results. The software will visualize the 3D myocardial tracking on multiple short and long axis planes and the corresponding strain values of the 17 standard left ventricle segments throughout the cardiac cycle frame by frame.

Time strain curves and a bullseye plot will be displayed. The longitudinal, circumferential, radial and area strains, rotation and torsion, will also be calculated and can be demonstrated. Then to terminate the analysis, click approve and exit.

Here, a 3D analysis of the left ventricle in a healthy volunteer with normal ventricular volumes and function, is shown. This 3D left ventricle analysis of a 64 year old male patient, shows a dilated cardiomyopathy and a wide QRS complex of the left bundle branch block morphology. The analysis of myocardial mechanics by 3D speckle tracking, provides meaningful data on dyssynchronous contractions and segmental dysfunction.

When attempting this protocol, keep in mind that despite all these advancements in trans-user and software technology, a good quality image of the heart is necessary to achieve accurate results. 3D echocardiographic assessment of ventricle structure and function is no longer just a scientific toy. It is ready for everyday when called prime time.