The vascular pedicle of the heart and the vena azygos. Part I: The normal subject.

The widths of the systemic vessels extending from the thoracic inlet to the heart (the vascular pedicle) and of the azygos vein were measured in 83 normal volunteers and 42 patients with cardiac disease. Mean vascular pedicle width ( VPW ) (erect) was 48 +/- 5.0 mm and correlated well with body weight (r = 0.64) and surface area (r = 0.62). Rotation to the left reduced VPW and to the right increased it. Inspiration and expiration caused little change. The supine VPW increased an average of 20% (47 +/- 37% to the compliant venous right side and 7 +/- 48% to the less compliant arterial left). Supine azygos width (AW) increased 105 +/- 47%. Mean erect AW was 5.14 +/- 1.36 mm. AW did not correlate significantly with anthropomorphic characteristics. Because VPW correlates with the patient's physique, its normality can be estimated within clinically useful limits by inspection. Since AW has no such correlation, serial changes are of more value than initial absolute values.