In vivo testing of a right heart mini-pump during a 24 hour period: is it safe?

A coaxial atrial cannula connected to a mini-centrifugal pump was developed to bypass the right heart during extreme exposures in off-pump coronary artery bypass surgery. This study was designed to test the effect of thispump, running during 24 hours, on blood elements to evaluate its use as a prolonged right heart support. In a calf model (body weight 68 ′ 5 kg), the pump was inserted and set to its maximal motor speed of 7000 rpm. Blood samples were drawn every 6 hours for blood gas analyses, as well as for hematology and chemistry. The right heart mini-pump performed perfectly at its maximal speed over the 24 hour period. Blood gas parameters and blood lactate levels reflected adequate tissue perfusion (baseline: 2.2 ′ 0.5 mmol/L vs. 24 h: 2 ′ 0.3 mmol/L; p = 0.64). Red blood cell count was stable (baseline: 9.8 ′ 1.4 x 10 1 2 /L vs. 24 h: 9.6 ′ 1.1 x 10 1 2 /L; p = 0.83). Free plasma hemoglobin remained below 100 mg/L throughout the experiment. Platelet count was stable during the first 6 hours and exhibited a tendency to drop thereafter (baseline: 749 ′ 104 x 10 9 /L vs. 24 h: 486 ′ 20 x 10 9 /L; p = 0.01). This right heart mini-pump appears to provide sufficient blood flow during a 24 hour period with minimal impact on red cell and moderate platelet damage after 6 hours. These results suggest a potential application of this system for post-cardiotomy right heart support.