Complex sentence: In 1972, at age 76, Kimball began experiencing difficulty breathing, excessive fatigue, and sleeplessness, and medical examinations discovered serious aortic calcification and some coronary artery disease.
Split into simpler sentences: In 1972, at age 76, Kimball began experiencing difficulty breathing, excessive fatigue, and sleeplessness. Medical examinations discovered serious aortic calcification and some coronary artery disease.