The application of transthoracic dynamic three-dimensional echocardiography by computer-controlled parallel slicing in patients with fixed subaortic obstruction

Abstract

AbstractA 64-element phased-array echocardiographic transducer mounted on a sliding carriage was used transthoracically in 11 patients with subaortic obstruction caused by various different morphological substrates. The transducer is moved in a plane from the outflow tract to the apex of the heart in steps of 0.5 to 1.3 mm and records a tomographic slice of the heart at each step. Parallel images are recorded at a frame rate of 25–30 images per second and triggered to heart rate and respiration. A complete cardiac cycle is recorded at each level. The images are digitized and stored in the image-processing computer, which reconstructs the anatomic structures of the heart in a three-dimensional format by means of different gray-scales. Good quality echocardiographic pictures were obtained in 10 of the 11 patients and three-dimensional reconstructions were possible in those 10 patients. The technique is able to display the heart in real-time in any desired plane, and in up to five planes simultaneously, without the need to change the position of the transducer on the chest. Thus the best views with which to display the substrate of subaortic stenosis could be selected. The left ventricular outflow tract could also be displayed in a view similiar to the one obtained by the surgeon during operative procedures for resection of the subaortic stenosis through an incision in the aortic root. Image acquisition took three to five minutes, and three-dimensional reconstruction of various cardiac structures took 20–90 minutes. Display of the subaortic area in three-dimensional format may enhance our understanding of cardiac anatomy and identify the different morphological lesions in the left ventricular outflow tract which cause subaortic obstruction.