Depending on the anatomical features, primary defects (in the proximal part of the septum, at its base – partial atrioventricular canal, in the region of the coronary sinus) and secondary, located in the area of the oval fossa, are isolated. EchoCG diagnosis of malformation includes the detection of the defect of the MPP and its indirect signs (volume overload of the right sections, pulmonary hypertension).
The defect of the septum in the form of a “discontinuous” signal is well visualized in B-mode from the parasternal access along the short axis at the level of the vessels or from the subcostal along the long axis. One should keep in mind the possibility of false positive diagnostics of the defect on the basis of this symptom only, since in the oval window area the partition is often very thin.
In addition, in the M – and B-modes reveal dilatation of the cavities of the PP and the pancreas with the expansion of the pulmonary trunk, as well as the paradoxical movement of the IUP. A Doppler study can detect low-speed left-right flow through the septum, which begins in the middle of ventricular systole and overlaps diastolic transmitral blood flow, and when assessing flow on the pulmonary trunk, an increase in pressure gradient and signs of pulmonary hypertension. When color Doppler mapping is clearly visible pathological flow through the WFP.
It should be noted that most authors do not consider the presence of an open oval window a congenital defect as such (cardiac hemodynamics does not suffer, since it is normally covered by a valve on the LP side). Contributes to the functioning of an open oval window only the formation of pulmonary hypertension of both heart (shunt) and pulmonary origin (in diseases of the lungs).