| Wide splitting of S2 with maintained inspiratory delay of P2 |
| Delayed activation and completion of right ventricular ejection |
| Complete right bundle branch block |
| Artificial left ventricular pacing |
| Pre-excitation of the left ventricle (Wolff-Parkinson-White syndrome) |
| Premature beats and idioventricular rhythm originating from the left ventricle |
| Prolonged right ventricular ejection time |
| Pulmonary hypertension with right heart failure |
| Right ventricular outflow obstruction (eg, pulmonic stenosis, acute massive pulmonary embolus) |
| Increased pulmonary hangout time |
| Idiopathic dilatation of the pulmonary artery |
| Mild pulmonic stenosis |
| Postoperative atrial septal defect |
| Decreased left ventricular ejection time (early A2) |
| Mitral regurgitation |
| Ventricular septal defect with low pulmonary vascular resistance |
| Constrictive pericarditis |
| Fixed splitting of S2 |
| Unchanged right ventricular stroke volume during respiration; severe right ventricular failure due to any cause |
| Interatrial communication; atrial septal defect; common atrium |
| Reversed splitting of S2 |
| Delayed left ventricular activation and completion of ejection |
| Left bundle branch block |
| Artificial right ventricular pacing |
| Pre-excitation of the right ventricle (Wolff-Parkinson-White syndrome) |
| Premature beats of right ventricular origin |
| Prolonged left ventricular ejection time |
| Increased resistance to left ventricular ejection (aortic stenosis, obstructive hypertrophic cardiomyopathy, hypertension) |
| Isolated increase in left ventricular forward stroke volume (aortic regurgitation, patent ductus arteriosus) |
| Myocardial dysfunction (mild to moderate left ventricular failure, myocardial ischemia or infarction) |
| Increased aortic hangout time (not the sole cause) |
| Aortic regurgitation |
| Patent ductus arteriosus |
| Aortic stenosis |
| Single S2 |
| Apparent: obesity, emphysema, pericardial effusion |
| Absent A2: severe aortic stenosis, severe aortic regurgitation |
| Absent P2: absent pulmonary valve, pulmonary atresia, tetralogy of Fallot, truncus arteriosus |
| Fusion of A2 and P2: Eisenmenger ventricular septal defect, common ventricle |
