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Figure 1 Impact sites used in this experimental model of commotio cordis. All chest blows were delivered with a regulation baseball at 30 mph. The LV anterolateral papillary muscle and base and apex of the LV were defined by direct anatomic visualization with transthoracic echocardiography. Distances to the other chest wall sites (unrelated to the heart) were defined using the papillary muscle as a reference point. Not shown here are the right chest wall sites. LA = left atrium; LV = left ventricle; RV = right ventricle.