User:Sunae712/Bidirectional Glenn procedure

Bidirectional Glenn Shunt or Hemi-Fontan Procedure
The bidirectional Glenn shunt or hemi-Fontan procedure is one of several surgical techniques used to temporarily improve cardiac function in patients with severe structural heart disease which feature single ventricular physiology. Patients with certain severe valvular or ventricular anomalies (e.g. hypoplastic left heart syndrome or single ventricle, etc.), have an abnormal cardiopulmonary circuit in which a single ventricle functionally serves as the driver of both systemic and pulmonary circulations. Typically, the bidirectional Glenn shunt is the second in a series of three staged surgeries to reconstruct a single ventricle heart, in situations where corrective bi-ventricular surgery or cardiac transplantation are not feasible. This stage in the process is crucial and carries a 96-99% survival rate.

In children, right ventricular morphology for children with single ventricle problems (e.g. hypoplastic left heart syndrome, double outlet right ventricle, d-transposition of the great arteries, etc.) is associated with poorer ventricular function and even worse regurgitation of the atrioventricular valve. In 499 consecutive studies involving patients with univentricular palliation, d'Udekem et al. showed that children with morphologically right ventricle have a 2.2 fold increased mortality prior to the bidirectional Glenn stage.

The bidirectional Glenn shunt procedure involves rerouting circulation such that the superior vena cava (SVC) is connected end-to-end with the right pulmonary artery, thereby draining into it. This helps to establish a in-series arrangement of both pulmonary and systemic circulations, resulting in deoxygenated blood returning from the head and upper body directly routed to the pulmonary arteries for oxygenation by the lungs. This, to some extent reduces the ventricular workload since the volume load is decreased. Since the blood passing from the SVC into the pulmonary arterial system flows bidirectionally to both right and left lungs, it is called a bi-directional Glenn procedure.

The Glenn procedure was introduced in 1958 by William Glenn and modifications to the procedure were published by Dr. Azzolina in 1973. The original description by Dr. Glenn allowed communication only between the right pulmonary artery and the SVC, whereas the modified technique had the SVC connecting at or before the bifurcation between the right and left pulmonary arteries.

In terms of transplantation, patients who have previously undergone a bidirectional Glenn procedure may require a longer segment of innominate vein.

Heart procurement steps for patients with a previous bidirectional Glenn:


 * 1) The aorta is dissected distally after the brachiocephalic (also known as innominate) artery branches off.
 * 2) The needle for administering preservation solution is placed into the ascending aorta and fixed at that location. When other teams have finished procuring their respective organ dissections, heparin at 300 U/kg is administered.
 * 3) The donor heart must be emptied. This is the most important step in heart transplantation procurement. An incision is made on the right side of the pericardium at the level of the hemidiaphragm down to the inferior vena cava (IVC).
 * 4) A clamp is placed on the SVC and IVC transected sot hat blood from the heart empties into the right cavity of the chest.