[Non-invasive methods in the study of the elastic properties of the thoracic aorta. Effect of isosorbide dinitrate].

The role of the great arteries is to distribute and stock blood. Pulsatile discontinuous flow is transformed to a continuous flow system. The elastic properties of the aorta play a major role in these functions. It is generally agreed that changes in these elastic properties may lead to the development of left ventricular hypertrophy. The evaluation of the aorta has, until recently, depended on invasive hemodynamic and angiographic techniques. In addition, the measurement of pulse wave velocity, though useful, is a global and only an approximate method. Transoesophageal echocardiography (TEE) enables accurate measurement of the aortic diameter and its systolo-diastolic variations. The accuracy of these measurements has been validated in vitro and the reproducibility is much better than with previously used techniques. Previous studies have shown an improvement of the elastic properties of the great arteries with nitrate derivatives. In recent studies using TEE, isosorbide dinitrate caused dilatation of the descending thoracic aorta and thereby improved its elastic properties. The development of tonometry techniques in our department has resulted in the finding of excellent correlations between carotid and aortic pulse pressures measured non-invasively. The association of TEE and tonometry thereby provides a direct approach to the evaluation of aortic compliance. It has then become possible to study the effects of nitrate derivatives on the aortic compliance of elderly patients in whom it is the most reduced.