DDX:

• Aortic regurgitation: an early diastolic decrescendo murmur best heard at the right second intercostal space. Most commonly associated with endocarditis, acute rheumatic fever and aortic root dilation.
• Aortic stenosis: a crescendo-decrescendo systolic murmur best heard at the upper right sternal border(RUSB) that radiates to the carotid arteries. It classically occurs secondary to age-related fibrotic and calcific changes of the valve but can occur earlier in life in cases of bicuspid aortic valve or chronic rheumatic heart disease.

• Atrial septal defect: results in a left-to-right shunt with abnormal flow of blood from the left atrium to the right atrium. This causes relative volume overload of the right atrium and ventricle, which presents as a fixed, split and low-grade physiologic ejection murmur.

• Coarctation of the aorta: narrowing of the aorta. Associated with a bicuspid aortic valve and Turner syndrome. It typically presents with a systolic murmur along with differential pulses and blood pressures between extremities.

• Mitral regurgitation: a holosystolic murmur best heard at the left fourth or fifth intercostal space along the midclavicular line and radiates to the left axilla. It is commonly a/w: mitral valve prolapse, endocarditis, acute rheumatic fever, and prior myocardial infarction.

• Mitral stenosis: classically heard as an opening snap followed by a diastolic rumble, loudest over the cardiac apex and radiates to the axilla. If severe enough, it can result in left atrial enlargement, cardiogenic pulmonary edema, and arrhythmias such as atrial fibrillation and flutter.

DDX:

• Patent ductus arteriosus: results in a continuous, machine-like murmur best heard at the left second intercostal space radiating to the clavicle.

• Pulmonic stenosis: a systolic murmur best heard at the second left intercostal region; it is also often crescendo-decrescendo, though it is quieter and radiates less to the lower neck than aortic stenosis because of the lower pressure in the pulmonary circulation. Pulmonic stenosis is typically seen in tetralogy of Fallot.

• Tricuspid regurgitation: a holosystolic murmur best heard at the left lower sternal border; it may result from severe pulmonary hypertension or infective endocarditis in IVDU.