Disparity in Blood Pressure Between Arms

To the Editor.—  While the consultants in QUESTIONS AND ANSWERS (237:1871, 1977) are correct in stating that the most common cause of dissimilar blood pressure readings in the arms of a 77-year-old man is arteriosclerotic occlusion of the subclavian artery, they make no mention of alternative explanations that may be responsible or contributory. Asymmetrical sphygmomanometric recordings can occur with the scalenus anticus syndrome, a cervical rib, or other forms of the thoracic outlet syndrome. Adson's test is usually positive in these cases.¹Anesthesiologists as myself occasionally give anesthesia to these patients for unrelated surgery, and often positioning them on the operating table can incur a spurious hypotension in the affected arm. Contralateral normalrange Korotkoff sounds delineate the discrepancy, and repositioning amends it.Unilaterally diminished arterial pulsations may also be seen status after open heart surgery or cardiac catheterization.Checking the blood pressure in both arms is worthwhile not only