Abstract
We have developed a dilatable cannula to reduce the inflow resistance of a bloodcircuit and increase the efficiency of assistance during left ventricular bypass. The inner diameter of the cannula is controlled by using shape memory alloy (SMA). A single wire of SMA, the diameter of which is 0.28 mm, is knit a tubular shape. The dilated shape of the tube is “ memorized ” when it is heated. Afterword, the diameter of the tube of SMA is decreased by hand. Finally, the SMA tube is covered with silastic rubber. Heating the cannula allowed dilation of its diameter to 175% that obtained at the room temperature. The effect the cannula's dilation on decreasing its flow resistance was examined. The pressure difference between the inlet and outlet of the cannula decreased to one-half that of a nondilated cannula at the same flow rate.
