[Dynamic transthoracic and transesophageal tridimensional echocardiography using rotational technique. A new perspective in echocardiography].

BACKGROUND

For many years, there has been a long-standing interest in developing three-dimensional echocardiography and several approaches have been followed. However, the main interest has been centered on reconstruction of left ventricular cavity. So far, dynamic three-dimensional representation of cardiac structures has been rather disappointing.

OBJECTIVES

In this study, we describe the clinical application of dynamic three-dimensional echocardiography with a rotational imaging acquisition.

METHODS

Three-dimensional echocardiography was performed in 50 patients referred to the Echocardiographic Laboratory at the Thoraxcenter for routine standard two-dimensional echocardiography (multiplane transesophageal = 30 patients; transthoracic = 20 patients) for different reasons. For transthoracic echocardiography, patients with good quality images were selected. We used prototype ultrasound probes connected to commercially available echocardiographic equipments interfaced to the Echo-Scan system. The steering logic of the system controlled the image acquisition in a given plane, at a predetermined moment in the respiratory and heart cycles (respiratory and ECG gating). Ninety rotational (2 degree interval) sector images of the heart were collected. The images were digitized, reformatted and interpolated, yielding a three-dimensional data set. From this data set, any desired cross-section of the heart could be computed, volume rendered and displayed in motion. Different algorithms were applied and mixed to produce a shaded dynamic three-dimensional display of cardiac anatomy.

RESULTS

Acquisition of images and three-dimensional reconstructions were possible in all the patients. Both conventional and unusual projections were displayed. Thus, we were able to represent the cardiac structures from cutting planes which could not be visualized from standard transthoracic or transesophageal approaches. In particular, in patients with mitral valve prolapse and mitral stenosis the left atrial "surgical" view on the valve provided additional information on both site and extent of leaflets pathology. The presence and the degree of systolic anterior movement were seen in all the patients with hypertrophic cardiomyopathy and outflow obstruction, and the site of the leaflet involved identified.

CONCLUSIONS

Dynamic three-dimensional echocardiography is clinically feasible and has the potential to offer information unavailable with conventional two-dimensional echocardiography. Rotational scanning is the logical extension of multiplane transesophageal probe, and circumvents the limitations due to the small acoustic windows during precordial acquisition.