Explain Continuous Murmurs and their characterstic in details?

These murmurs are continuous throughout systole and diastole. It is due to continuous blood flow in the same direction in both systole and diastole unlike a to and fro murmur in which blood flows in one direction in systole and in opposite direction in diastole.

Figure: Continuous

Characteristic: High pitch continuous "Machinery murmur best heard in the second left intercostal space with radiation to chest, neck and back. It typically begins after S₁, gradually increases in intensity, peaks at or immediately after S₂ and gradually fades to a variable duration in diastole depending oil pulmonary arlery pressure; the higher the pressure lesser the duration of murmur in diastole. There are some additional clicking sounds in late systole and in early diastole, called Eddy sounds are very characteristic of a continuous murmur caused by PDA.

If the next loudest sound is not heard in the first left interspace but heard in the third left interspace the diagnosis of PDA should not be entertained and the other causes of continuous murmur such as coronary artery cameral fistula into RA/RV or Ruptured Sinus of Valsalva should be kept in mind.