How is the Senning atrial switch procedure performed?

How the Senning Procedure is Performed

The Senning procedure is an atrial switch operation that uses autologous atrial tissue flaps to create intra-atrial baffles that redirect systemic venous blood to the mitral valve/left ventricle and pulmonary venous blood to the tricuspid valve/right ventricle, achieving physiological correction in transposition of the great arteries. 1

Surgical Technique

Core Principle

The Senning operation redirects blood flow at the atrial level by constructing venous pathways using the patient's own atrial tissue rather than synthetic material 1, 2. This distinguishes it from the Mustard procedure, which uses Dacron or pericardial patches 1.

Key Technical Steps

Atrial Septal Flap Construction:

• The interatrial septum is utilized to create flaps that form part of the new venous pathways 2
• When the atrial septal flap is deficient (such as at an atrial septal defect site), the flap is "filleted" to enlarge it using living tissue 2
• This filleting technique also thins the septal flap, which enlarges the left pulmonary vein pathway located posterior to the floor of the new caval tunnels 2

Superior Vena Cava Pathway:

• The upper end of the sulcus terminalis is incorporated into the construction of the roof of the new caval tunnels 2
• The upper posterior rim of the right atriotomy is left external to this suture line and used in constructing the new pulmonary venous pathway 2
• This suture line is placed inferior to the sinoatrial node, allowing expeditious placement with reduced risk of SA node damage 2

Venous Baffle Creation:

• Systemic venous blood (from superior and inferior vena cavae) is redirected to flow across the mitral valve into the left ventricle, which remains connected to the pulmonary artery 1, 3
• Pulmonary venous blood is redirected to flow across the tricuspid valve into the right ventricle, which remains connected to the aorta 1, 3

Technical Modifications for Complex Anatomy

In patients with dextrocardia or atrial isomerism:

• The procedure can be performed through the left-sided atrium with appropriate modifications 4, 5
• Adjustments are required for anomalous systemic venous drainage patterns, including bilateral superior vena cavae 5

In congenitally corrected transposition (ccTGA):

• The Senning procedure is used as part of a "double-switch" operation combined with arterial switch 3, 6
• Special attention must be paid to cardiac malposition and conduction system anatomy 7

Operative Approach

Cardiopulmonary bypass technique:

• Most patients undergo profound hypothermia with total circulatory arrest during repair 8
• The procedure is typically performed in early infancy following initial palliation with Rashkind atrial septostomy 8

Critical Anatomical Considerations

The extensive suture lines created during atrial baffling are directly responsible for:

• High incidence of sinus node dysfunction (>50% by adulthood) due to surgical trauma near the sinus node or its arterial supply during superior vena cava limb creation 3, 9
• Development of intra-atrial reentry tachycardia (up to 30% of patients), typically involving macroreentry circuits around the tricuspid valve border 3, 9

Common pitfall: The narrow conduction corridor between the inferior vena cava limb of the baffle and the tricuspid valve ring supports atrial flutter circuits 3.

Advantages Over Mustard Procedure

The Senning technique using autologous tissue has demonstrated:

• Lower incidence of pathway obstruction 7
• Reduced baffle leak rates 7
• Fewer significant late arrhythmias compared to synthetic material approaches 7