Real‐time Three‐dimensional Echocardiography, a New Approach to Cardiac Anatomy in Live Dogs and Cats

Abstract

Macroscopic anatomy of the heart is evaluated best in living animals, because postmortal changes and the lack of the normal heart motion lead to misinterpretation. For the last 15 years functional cardiac imaging of animals has been performed by two‐dimensional ultrasonography. However, three‐dimensional echocardiography has multiple advantages over two‐dimensional ultrasonography such as an improved assessment of the endocardial structures and the possibility of precise determination of the sonographic views for measurement. For these reasons the ultrasound system SONOS 7500 of Philips has been used for examinations since December 2003. These examinations were performed in healthy adult dogs of different sizes as well as in European Short Hair cats. Using a recently developed multi‐frequent matrix array probe all regions of interest were directly on‐line volume‐rendered or represented in two exactly defined orthogonal views. Although the used matrix array probe was large, transthoracic left and right parasternal sonograms could be carried out without any problems in all small animals without sedation. For the first time the cardiac structures in dogs and cats such as the opening and closing of the left atrioventricular and aortic valves were represented within a 60 degrees (15 or 30 degrees pyramidal volume. The morphology and the function of the atrioventricular leaflets could be evaluated exactly. For representation of a larger pyramidal volume or the three‐dimensional simultaneous colour flow imaging, careful ECG gating is required. Unfortunately, the distinct respiratory arrhythmia in quiet dogs had a negative effect on the registration of four or eight heart cycles of the same length. Using biplane echocardiography the commonly represented sonographs for measurement were exactly determined. Additionally these techniques enabled the registration of new views for evaluation and measurements, which were not available from two‐dimensional ultrasonography. This study has demonstrated for the first time that real time transthoracic three‐dimensional echocardiography is feasible in dogs and cats and that it provides comprehensive visualization of the intracardiac anatomy in unique projections in living animals.