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Percutaneous Insertion and Removal Technique of Bio-Medicus Cannula as SVC Cannula for Cardiopulmonary Bypass
The authors have been performing mitral valve repair using minimally invasive and/or robotic techniques for twelve years at Liverpool Heart and Chest Hospital in the United Kingdom. All the authors' patients, regardless of body size, have percutaneous SVC cannulation through the right internal jugular vein (IJV) with a Bio-Medicus cannula, usually 17 French (Fr) or 19 Fr, and occasionally 21 Fr, in addition to femoral venous cannulation with a 23/25 Fr dual stage cannula.
Ensuring adequate venous drainage is of paramount importance, as this reduces rewarming of the right heart in the context of a closed chest, where it is likely that the heart rewarms more quickly—as it is effectively wrapped in a warming jacket—compared to a sternotomy. A good analogy for this phenomenon is an ice cube in one's hand: the ice cube will melt more quickly when one's hand is wrapped around it (as in a minimally invasive procedure) as compared to an ice cube resting on the palm of the hand (as in a sternotomy). This is why systemic cooling assumes a greater importance in minimally invasive mitral surgery compared to sternotomy.
This setup provides adequate venous drainage in 100 percent of cases when combined with three other techniques, one or all of which may be needed. These techniques include 80–90 percent reduction of arterial flow, variation in vacuum assistance from -10 to -30 mmHg, and hitting the “sweet spot” of the femoral venous cannula, usually close to the inferior cavoatrial junction but sometimes only found by varying the depth of insertion of the cannula and watching the RA collapse down.
The authors’ technique of percutaneous SVC cannulation has evolved and become more expeditious over the last decade. They have dispensed with the following:
- An assistant/scrub nurse.
- The use of long guidewires that come in the dilator packs (0.035 in/150 cm); they now use shorter (0.032 in, 60 cm) wires that come with the central venous catheter cannulation packs.
- The use of dilators, as the Bio-Medicus cannula has a dilating tip; now they simply use an 11-blade to follow the guidewire.
- Variation in depth of insertion; all are now inserted to 12 cm, which sits the tip of the cannula high in the SVC and thus cephalad to the Chitwood clamp, if one is used).
The authors have also suspended performing manual compression of the internal jugular vein during decannulation, as this leads to intravascular thrombus formation, which could compromise future use of it. Instead, they simply snug down on a purse-string suture and allow the IJV to form a small extravascular subcutaneous hematoma. This can be completed as the surgical team is closing. Once hemostasis is achieved, the purse string is removed and skin glue is applied.