title: New, Virtually Wall-less Cannulas Designed for Augmented Venous Drainage in Minimally Invasive Cardiac Surgery.
abstract: OBJECTIVE
  Inadequate venous drainage during minimally invasive cardiac surgery becomes most evident when the blood trapped in the pulmonary circulation floods the surgical field. The present study was designed to assess the in vivo performance of new, thinner, virtually wall-less, venous cannulas designed for augmented venous drainage in comparison to traditional thin-wall cannulas.
  
  
  METHODS
  Remote cannulation was realized in 5 bovine experiments (74.0 ± 2.4 kg) with percutaneous venous access over the wire, serial dilation up to 18 F and insertion of either traditional 19 F thin wall, wire-wound cannulas, or through the same access channel, new, thinner, virtually wall-less, braided cannulas designed for augmented venous drainage. A standard minimal extracorporeal circuit set with a centrifugal pump and a hollow fiber membrane oxygenator, but no in-line reservoir was used. One hundred fifty pairs of pump-flow and required pump inlet pressure values were recorded with calibrated pressure transducers and a flowmeter calibrated by a volumetric tank and timer at increasing pump speed from 1500 RPM to 3500 RPM (500-RPM increments).
  
  
  RESULTS
  Pump flow accounted for 1.73 ± 0.85 l/min for wall-less versus 1.17 ± 0.45 l/min for thin wall at 1500 RPM, 3.91 ± 0.86 versus 3.23 ± 0.66 at 2500 RPM, 5.82 ± 1.05 versus 4.96 ± 0.81 at 3500 RPM. Pump inlet pressure accounted for 9.6 ± 9.7 mm Hg versus 4.2 ± 18.8 mm Hg for 1500 RPM, -42.4 ± 26.7 versus -123 ± 51.1 at 2500 RPM, and -126.7 ± 55.3 versus -313 ± 116.7 for 3500 RPM.
  
  
  CONCLUSIONS
  At the well-accepted pump inlet pressure of -80 mm Hg, the new, thinner, virtually wall-less, braided cannulas provide unmatched venous drainage in vivo. Early clinical analyses have confirmed these findings.
authors: From the *Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; †Toronto General Hospital, Toronto, Ontario, Canada; ‡CardioCentro, Lugano, Switzerland; and §Department of Cardiovascular Surgery, University Hospital, Zurich, Switzerland.
authors: Ludwig Karl
authors: LK
authors: von Segesser
authors: Denis
authors: D
authors: Berdajs
authors: Saad
authors: S
authors: Abdel-Sayed
authors: Piergiorgio
authors: P
authors: Tozzi
authors: Enrico
authors: E
authors: Ferrari
authors: Francesco
authors: F
authors: Maisano
mesh_terms: D000818:Animals; D006348:Cardiac Surgical Procedures / Q000295:instrumentation*; D002404:Catheterization; D002417:Cattle; D004322:Drainage / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation / Q000379:methods; D023421:Models, Animal; D014680:Veins