Mid-systolic murmurs begin at a short interval following S1, end before S2 (Fig. e8-1C), and are usually crescendo-decrescendo in configuration. Aortic stenosis is the most common cause of a mid-systolic murmur in an adult. The murmur of AS is usually loudest to the right of the sternum in the second intercostal space (aortic area, Fig. e8-2) and radiates into the carotids. Transmission of the mid-systolic murmur to the apex, where it becomes higher pitched, is common (Gallavardin effect, see above).