The case described was a MVR+CABG. The circuit used had been primed for a possible case which was then cancelled the day prior. The cardioplegia (CP) circuit had a leukoguard BC2 filter placed between the oxygenator and the cardioplegia pump. A microplegia system was used. Following aortic cross clamp, 7 litres of cardioplegia were given in both ante and retro directions, approx. every 15 minutes.
Following a 15-minute period a further dose of CP was requested but as the cardioplegia pump was turned on the CP line pressure immediately rose over 300mmHg and the pump stopped and alarmed. The line was checked to the table for clamps or occlusions. The surgeon checked the system and stated that everything was unclamped at the table. The CP delivery line was then disconnected from the CP cannula and placed over a bowl whilst we tried to pump CP again. However, the pressure in the system immediately shot up to 300mmHg with no flow into the bowl. Flow could be achieved through the CP circuit recirculation line, so the table line was under suspicion.
A new table line was handed up to the table. As the original CP table line was disconnected a long clot slid out of the tubing and onto the floor. The ACT at this point was 462 (sample taken 10 mins earlier) and this was the lowest it had been. An extra 5000iu was given as a precaution. The main circuit was thoroughly checked for clots, but none were evident, and the surgeon stated no clots were visible anywhere in the chest. I discarded the whole CP circuit and set up a new one. By this time the surgeon was ready to remove the cross clamp, so no more CP was required.
On later inspection of the old CP circuit, clot was evident all around the bubble trap section of the heat exchanger. In addition, the BC2 filter seemed clogged post filter membrane. There was no apparent harm to the patient from this incident in terms of coming off CPB and the patient’s post-op course was as expected.
