What is a bidirectional Glenn procedure (BDG)? Cardiology Basics

What is a bidirectional Glenn procedure (BDG)? Cardiology Basics

Bidirectional Glenn procedure is done for children with some types of cyanotic congenital heart diseases.  The classical Glenn procedure is an end to end anastomosis of the superior vena cava to the right pulmonary artery so that the superior vena caval venous blood does not reach the left pulmonary artery. Bidirectional Glenn (BDG) procedure is an end to side anastomosis of superior vena cava to the right pulmonary artery. Main pulmonary artery is then divided and sutured. BDG helps flow into both pulmonary arteries. BDG is usually followed later by a Fontan repair.

BDG is performed in patients with anatomical or functional single ventricle, as a palliative procedure. Functionally single ventricle means that the other ventricle is very small or obstructed. Hypoplastic left heart syndrome (HLHS) is one such condition in which left ventricle is very small. Along with it, left atrium and aorta are also hypoplastic in HLHS. BDG is done for an initial palliation in HLHS. Tricuspid atresia is another condition in which BDG is done.

Bidirectional Glenn procedure improves systemic arterial oxygen saturation without increasing pulmonary vascular resistance. BDG can lead to systemic venous collateral development and pulmonary arteriovenous malformations later. Potential advantages of the bidirectional Glenn procedure are the early elimination of volume overload on the functionally single ventricle, avoiding the need for systemic to pulmonary artery shunts and pulmonary artery bands. It also simplifies the operative procedure at the time of future Fontan repair.

Some are in favour of leaving an accessory source of pulmonary blood flow like a systemic to pulmonary artery shunt or a patent right ventricular outflow tract at the time of BDG. But there is some data to suggest that morbidity and mortality are lower in patients in whom accessory pulmonary blood flow is eliminated at the time of BDG. Bidirectional Glenn procedure can be done even at a very young ages of less than 3 months. It can be done with and without cardiopulmonary bypass.