Congenital communication between the left ventricle and the right atrium. Acquired forms have been described after myocardial infarction, endocarditis, cardiac surgery or chest trauma. Based on the implantation of the septal leaflet of the tricuspid valve, the membranous part of the interventricular septum can be divided into two portions: the interventricular apical portion and the atrioventricular basal one. Since the tricuspid valve is implanted one centimeter below the mitral one, the atrioventricular portion separates the RA from the ejection chamber of the LV.

It can be categorized as:

-        the direct type (type I or supravalvular) where the atrioventricular basal portion is opened causing direct reflux in the RA.

• the indirect type (type II or infravalvular) which is most common. The shunt is located at the apical portion and usually associated with a jet lesion on the septal leaflet of the tricuspid that can be consequently perforated, creating an indirect shunt in the RA.
• some authors describe a type III that combines the direct and indirect forms.

Consequences: systolic murmur similar to a VSD, left-right shunt with dilation of the RA and the LV, and often secondary tricuspid insufficiency.

Anesthetic implications: 

correction by interventional catheterization or open heart surgery.

References : 

-        Kelle AM, Young L, Kaushal S, Duffy CE, Anderson RH, Backer CL.
The Gerbode defect: the significance of a left ventricular to right atrial shunt.
Cardiol Young 2009;19 (Suppl 2): 96–9

Updated: July 2022