Pulsus paradoxus is characteristically seen in cardiac tamponade. Absence of pulsus paradoxus is seen when cardiac tamponade is associated with all except one
Mechanism of pulsus paradoxus:
Inspiration → increased RV filling and decreased LV filling → left shift of IVS → LV compression and decreased systolic arterial pressure.
Pulsus paradoxus  is absent  when cardiac tamponade occurs in a condition which permits equal filling of both ventricles or more filling of LV.

ASD= equal filling of both ventricles in both phases of respiration.
VSD=free communication between ventricles preventing differential filling.
AR= filling of LV is maintained irrespective of respiration
ASD
VSD
MR
AR