How can I achieve constant pressure in Langendorff Mode on my Radnoti Isolated Heart System?

A constant pressure is set using gravity and the elevation of the Aortic Bubble Trap Compliance chamber. 1mmHg = 13.6mm water. Typically 1 meter of elevation is recommended. If you are having difficulty with setting and maintaining a constant pressure please check the following:

  • Elevation of the Aortic Bubble trap with relation to the heart.
  • Vent port on Aortic Bubble Trap is open. Placing a 50ml disposable syringe with the plunger removed at the vent port stopcock will greatly reduce the chance of spillage and help to dislodge bubbles that can vapor lock the compliance port line returning to the reservoir. If this port is not in an open state, the fluid traveling down the compliance or overflow line returning to the supply reservoir will draw a negative pressure on the line feeding the aorta and distort pressure readings.
  • Compliance port set to open returning fluid to supply reservoir. If this port is not in the open state then excess perfusate supplied from the reservoir via the peristaltic pump will be forced to the aortic cannula, over-pressurizing the heart and causing rapid failure.
  • Peristaltic pump set to deliver perfusate at 1.5 – 2X anticipated flow rate. If the pump rate is set too low, the heart will consume buffer faster than the buffer is supplied and quickly drain the supply from the bubble trap. The flow rate should be set to at least 150% of the anticipated flow rate with excess buffer returning to the supply reservoir via the compliance/overflow port at the aortic bubble trap.
For more information, please download the Radnoti Trouble Shooting Guide