Figure 7.

Comparison of the ISF-plot obtained in a normal volunteer (A) and in a patient with WPW (B). Note the increased area of overlap (light green areas) around the isovolumic periods (between MVC-AVO and between AVC-MVO) and in particular the onset of vigourous shortening (onset of high blue spike, red arrow) starting during the end of atrial filling, long before MVC (red dashed line).