51 of the cavo atrial cannula is large enough to permit blood to flow freely within the lumen of the cavo atrial cannula and to avoid sheer stress on the blood cells when the cavo atrial cannula is properly inserted the first openings should be located inside the patient 39 s right atrium the first openings will be of sufficient size to permit the unobstructed flow of blood into the cannula and to minimize the disruption of red blood cells in fig1 the bend 18 is located at the junction of the middle portion 12 and upper portion 11 the angle of inclination 40 of the bend can range from approximately twenty five degrees 25 u00b0 to one hundred eighty degrees 180 u00b0 depending on the physical properties of material used to make the cavo atrial cannula if the material is flexible and can bend without creating a closure of the lumen of the device then the angle of inclination can be larger than one hundred thirty five degrees 135 u00b0 in the preferred embodiment the angle of inclination ranges between forty five degrees 45 u00b0 and one hundred thirty five degrees 135 u00b0 in fig1 and 2a the second openings 17 of the cavo atrial cannula is located at the junction of the upper portion 11 and the middle portion 12 on the outer.