Heart sounds and their abnormalities are as follows: FIRST HEART SOUND Soft: Mitral regurgitation, Low BP, Severe cardiac failure, Rheumatic Carditis, Left bundle branch block. Loud: Atrial fibrillation, Mitral stenosis, Atrial premature beat Variable intensity: Complete AV block, Varying degree of diastole Split: Right bundle branch block, Atrial septal defect, left ventricular ectopics, Ebstein's anomaly, Tricuspid stenosis SECOND HEART SOUND Soft: A2:Aortic valve calcification, aortic root dilatation P2: Pulmonary stenosis Loud: A2: High BP, Thin patients P2: Pulmonary hypertension, Atrial septal defect Wide splitting: Early A2: Mitral regurgitation, Ventricular septal defect Delayed P2: Right bundle branch block, pulmonary stenosis, Atrial septal defect, Right ventricular failure. Reversed splitting: Delayed A2: Left bundle branch block, Systolic hypertension, Hypertrophic obstructive cardiomyopathy, Severe aortic stenosis, Patent ductus arteriosus, Left heart failure Single: Aortic valve calcification, Pulmonary stenosis, Fallot's tetralogy, Ebstein's anomaly, pericardial effusion, Large Ventricular septal defect, Obesity, Emphysema THIRD HEART SOUND Right ventricle: Right heart failure, Tricuspid regurgitation, Atrial septal defect, Constrictive pericarditis Left ventricle: Mitral regurgitation, Anterior MI, Left ventricular failure FOURTH HEART SOUND Ventricular hypertrophy, Fibrosis, Hypertrophic obstructive cardiomyopathy