Figure 3.

TEM of LA of 3 Patients With MR

Transmission electron microscopy (TEM) of LA of 3 patients with MR demonstrates extensive myofibrillar breakdown with distortion of the z-disc and sarcomere, as well as collections of many small, disorganized, and multiple shaped mitochondria with sparsely packed cristae, extensive nonmembrane-bound vacuoles (v), lipid droplets (LD), lipofuscin (black arrows) and glycogen accumulation (red arrows). Patient #10 is a 50-year-old white male, with a LA maximum volume (MV) if 280 ml. His LA EF of 27% has multiple areas of myofibrillar loss that at a higher magnification (square) show the replacement by glycogen accumulation (dark black dots), empty vacuoles, and clusters of mitochondria with either dissolved or broken cristae. Patient #15 is a 59-year-old white male, with a LAMV of 71 ml. His LA EF of 50% also demonstrates large accumulations of glycogen and variably sized mitochondria that replace areas of myofibrillar loss. Patient #19 is a 59-year-old black male, with a LAMV of 88 ml. His LA EF of 40% has multiple areas of sarcomere stretch and contraction (box) with distorted z-discs and lipid droplets (LD), and electron dense particles of lipofuscin-containing lipid droplets (arrows). Abbreviations as Figure 1.