Figure 3.

Segmental LV radial strain during a (a) short-coupled LV PVC at 200ms, (b) long-coupled LV PVC at 375ms, (c) LV rapid VP at 400ms, (d) PAC at 200ms, (e) normal intrinsic beat. Direct visualization of contraction and radial strain in a short-coupled PVC (Panel a) demonstrate those segments near the origin of an early or short-coupled PVCs (LV free wall in green and light blue) have their peak maximum contraction immediately after peak contraction of the preceding intrinsic beat, which appears as a long fused peak contraction between intrinsic and PVC beat in segments near PVC origin. Few milliseconds later, the peak contraction of segments away from PVC origin (septal segments in red and dark blue) is noted while the first segments (near PVC origin) start relaxation (Supplemental Video 1). In contrast, segments near the origin of a late-coupled PVC (Panel b) have their peak radial strain after relaxation of the preceding intrinsic beat is almost completed, causing dyskinesia of the opposite segments, while the segments away from PVC origin have their peak contraction when the segments near PVC origin have already completed relaxation, leading to a visually apparent LV dyssynchrony (Supplemental Video 2). Yellow dot marks QRS of a normal intrinsic beat with a peak radial strain (yellow arrow) that occurs at least around 250ms after beginning of QRS. Red arrow marks QRS initiation of LV PVC in panel “a” and “b” (200, 375ms coupling interval) and PAC (200ms) in panel “d”. White arrow in panel “c” denotes the initiation of VP beat at 400ms. White dotted line marks dispersion of QRS-to-peak strain in all panels. Left lower quadrant in all panels is a representation of radial strain in all 6 segments (Y axis) plotted by time (X axis), with red color representing the peak radial strain (contraction) and blue color indicating the lowest radial strain (greatest relaxation).