Fig. 1

Effect of age and initial volume on thoracic aortic elastance. The slopes of the lines are elastance. The right upper insert shows the increase in circumferential tension versus increases in aortic circumference in percent for age < 18 to > 80 years [33]. The lower left shows a schematic pressure–volume relationship for the aorta. The boxes represent stroke volumes. The same stroke volume A starting from the same initial volume produces increasing pulse pressures depending upon the shape and position of the start of the stroke volume. The stroke volume B is the same size as in A but starts at a higher initial volume and produces a much larger pulse pressure