S3........lub - dub DUB normal in children and adults age up to 35 to 40 yrs  abnormal....HF
S4......LUB lub - dub
Abnormal...vent. hypertrophy due to HTN CAD cardiomyopathy aortic stenosis
When both s3 and S4 occurs...LUB lub - dub DUB refers as summation gallop