Ruptured heart cords. Gross specimen of a section through a heart, showing ruptured heart cords in a case of cardiac infarction (tissue death) during a heart attack. The cords are the chordae tendineae, fibrous bands of tissue that attach heart valves to groups of muscles on the heart wall. Several have snapped, including some at centre left. The wall of the heart (down right) is dark, indicating the tissue death of a heart attack. The cords can sometimes break and impair proper valve function, leading to leakage and eventually heart failure. A minor chordae rupture can be tolerated. A heart attack is usually caused by the blocking of blood flow to the heart muscle, leading to tissue death.