AGE-DEPENDENT INCREASE IN AORTIC STIFFNESS DURING NEGATIVE INTRATHORACIC PRESSURE IN HEALTHY-SUBJECTS

An acute reduction in intrathoracic pressure increases the transmural pressure of the thoracic aorta and cardiac chambers and thus left ventricular systolic wall stress as well.1 Forced inspiration against airway resistance (Mueller maneuver) has therefore been advocated as an afterload challenge to the left ventricle.2 The stiffness of the ascending aorta is another important determinant of left ventricular afterload and depends on the structure of the aortic wall and on the degree of aortic distention.3 In theory, negative intrathoracic pressure could increase left ventricular systolic load also by augmenting the stiffness of the proximal aorta through increased distention, but no direct data are available. In the present study, we measured aortic stiffness at rest and during the Mueller maneuver using 2-dimensional echocardiography of the proximal aorta together with continuous noninvasive blood pressure monitoring. To assess whether age-related changes in the aorta modify the effect of negative intrathoracic pressure, we compared the responses between groups of young and middle-aged healthy subjects. © 1993.