PMC

Examples of hemodynamic instability observed in study #2. Left column: Dampened, incomplete occlusion. Right column: Total intermittent occlusion.

Ovine Heart Preparation. (a) Tee-fitting attached to atrial remnant and tied with purse string. (b) Circulatory loop with cannulated LV and borescope inserted through T-tube. (Arrow indicates direction of flow.)

Conventional beveled ventricular cannula (white) and prototype (blue). (a) axial view; (b) side view; (c) flanged cannula deployed through small diameter opening in Plexiglas, illustrating retention by external flange.

(Left) Positional sensitivity index Ips for maximal attainable flow (regardless of speed) measured during the over-pumping protocol of the second study. (Right) Ips in flow for the hypovolemic protocol of the second study at a fixed speed of 1250 RPM. Arrow indicates time progression for hypovolemic protocol.

(Left) Flow versus speed for aligned and misaligned cannulae for initial LAP of 20mmHg up to the point of suction for the second study. (Right) Flow versus Pressure as preload is reduced with pump speed fixed at 1250 RPM for the second study. Arrow indicates time progression for hypovolemic protocol

External view of properly aligned beveled cannula with long axis of ventricle (a) and deflected ventrally by approximately 45 degrees (b). Panels (c) and (d) provide still images of respective particle flow fields generated for the beveled cannula, revealing particle deposition (circled) in the crevice between the cannula and endocardium.

Still images captured from borescopic video illustrating the progression of the three modes of suction from patent flow path (left) to nearly full collapse (right). (a) Concentric collapse of properly aligned flanged and beveled cannulae, (b) Instantaneous entrainment of a misaligned flanged cannula and (c) Gradual entrainment of a misaligned beveled cannula. View of the cannula lumen (1), flange (2), and bevel (3). Ventricular free wall indicated by arrow (4).