Continuous murmur and it’s differential diagnosis

Continuous murmurs are defined as "murmurs that begins in systole and extend through the second heart sound into part or whole of diastole".

They are produced due to pressure gradient between a high pressure area (Artery or Ventricle) and low pressure area (vein or right heart chamber)

Following are the causes of continuous murmur

1. Patient ductus arteriosus (PDA).
2. Rupture of sinus of valsalva - RSOV.
3. Aorto pulmonary window (AP Window).
4. Anomalous origin of left coronary aratery from pulmonary artery (ALCAPPA).
5. Surgical shunts - Blalock - Taussing in TOF.
6. Bronchopulmonary collaterals seen in TOF (Tetrology of fallot) tricuspid atresia, trances arteriosus.
7. Peripheral pulmonary artery stenosis.
8. Pulmonary embolism.
9. Pulmonary and coronary AV fistula.
10. Proximal pulmonary artery stenosis.
11. Intercostals AV fistula.
12. Collaterals in coarctation of aorta.
13. Venous hum.
14. Mammary souffle.

Site of murmur in continuous murmur

1. PDA                            - Left 2nd ICS (inter costal space)
2. AP window                 - left 3rd  ICS
3. Rsov                            - Left sterna border
4. Coronary AV fistula    -Left sterna border
5. Pulmonary AV fistula  - Left – 2nd ICS
6. Coarctation of Aorta     - Thoracic spine
7. Mammary soufflé         -Mammary and 2nd ICS

Differential diagnosis of continuous murmur

1. To and from murmur

1. They occur through single channel
2. Occupy mid systole and early part of idiastale
3. These murmurs want peak around  S2
4. Examples are : AS+AR, PAH + PR

Differentiation between continuous and To and Fro murmur

1. Continuous murmur
2. S2not heard
3. Uni directional
4. To & from murmur
5. S2heard Heard
6. Bi directional 

2. Systolic - Diastolic murmur

1. Murmur occur through different channels
2. Occupy systole and diastole
3. Does not peak around S2
4. Example : VSD + AR
5. Venous hum
6. Mammary Souffle

Types of continuous murmur