A muscle tear will leave a scar after healing.

肌肉撕裂在治愈后会留下伤疤。

《柯林斯英汉双解大词典》

Why, Discher wondered, don't heart muscle cells then replace the scar tissue?

迪斯凯尔想知道，为什么心肌细胞不取代疤痕组织呢？

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Over time, those patients will develop heart failure because injured heart muscle tissue damaged by the heart attack will eventually be replaced by stiff scar tissue.

久而久之，这些病人会得心力衰竭病因为在心脏病突发中损坏的心脏肌肉组织最终会被僵硬的伤疤组织所替代。

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Another common type of massage, so-called deep tissue, tends to be more targeted to problem muscles and includes techniques such as acupressure, trigger-point work (which focuses on little knots of muscle) and "deep transverse friction" where the therapist moves back and forth over muscle fibers to break up scar tissue.

WSJ: Don't Call It Pampering: Massage Wants to Be Medicine