Right atrial surgery without caval snaring.

Area of Science:

• Cardiovascular Surgery
• Medical Devices

Background:

• Tricuspid valve replacement may require right atrial access.
• Previous mitral valve surgery can complicate standard procedures.
• Incidental observation suggested right atrial opening without caval snaring is feasible.

Purpose of the Study:

• To test the hypothesis that the right atrium can be opened without caval snaring and without air entrainment.
• To evaluate air entrainment during right atrial surgery using percutaneous cannulation in an animal model.

Main Methods:

• Two patients underwent right atrial surgery with percutaneous cannulation without caval snaring.
• An animal model (2 pigs) was used to test the principle.
• Percutaneous cannulae were placed under epicardial echo guidance.
• A collapsible bag with air drainage system quantified air return from the superior vena (SVC) and inferior vena cava (IVC).
• Cannulae with and without proximal side holes were tested.

Main Results:

• No air entrainment occurred from the inferior vena cava (IVC) cannula in the animal model.
• Air was entrained from the superior vena cava (SVC) cannula at 60 mL/minute.
• Epicardial ultrasound showed complete collapse of both vena cavae.
• Partial clamping of the SVC cannula reduced air entrainment; a clamp at the SVC atrial junction eliminated it.
• No significant difference in air entrainment was observed between the two cannula types.

Conclusions:

• Inferior vena caval drainage via percutaneous cannula is safe without snaring, likely due to a competent Eustachian valve.
• The superior vena cava is susceptible to air entrainment during right atrial opening without snaring.
• Minimal SVC air entrainment can be managed with clamping techniques, avoiding the need for caval snaring.