Use of HTK-Cardioplegia for compex cardiac surgery: The Trondheim experience

Background: Myocardial protection during open heart surgery is traditionally achieved by infusing either cold crystalloid or cold, tepid or warm blood cardioplegia. To obtain a satisfactory protection with crystalloid or blood cardioplegia, the delivery has to be repeated every 15-25 minutes. Reinfusion can be made antegradely, a method that will prolong surgery or retrogradely, a method with bears problems with the protection of the right ventricle. The Bretschneider histidine- buffered solution is a crystalloid cardioplegia that requires a longer infusion time (2000 ml/6-8 min) but has the advantage of one single infusion. We have performed a feasibility study with the use of histidine-tryptophane-ketoglutarate cardioplegia (HTK, Custodiol) in patients undergoing long cardiac ischaemic arrest due to complex cardiac operations. Material and methods: Until August 2006, 15 patients underwent elective or emergency aortic valve operations combined with other cardiac surgery procedures. Custodiol was infused in the ascending aorta by a volumetric pump. Residual cardioplegia was aspirated from the coronary sinus through a balloon tipped cannula. Results: HTK cardioplegia (Custodiol) 1987±135 ml was infused over 6-7 min. Diastolic arrests occurred 122±82 seconds after the start of cardioplegia infusion; four hearts fibrillated before the arrest. In 10 patients 405±199 ml of cardioplegia were aspirated from the coronary sinus. Aortic cross-clamping time was 95±36 min. Two patients required an extra dose of cardioplegia because of a persistent cardiac mechanical activity during cross clamp. After release of the aortic cross-clamp, the heart restarted in sinus rhythm in seven patients and in ventricular fibrillation in eight patients. The fibrillating hearts were converted using and injection of KCl (23±5 mmol), while four patients required additional DC shocks. Four patients required temporary pacing after weaning from cardio-pulmonary bypass. Cardiac enzyme level 24 hours after surgery was within expected ranges for this type of patients: median CKMB 25.4 μg/L (12-365 μg/L) and Troponin-T 0.530 μg/L (0.194-25 μg/L). One patient with aortic valve endocarditis had a prolonged ventricular fibrillation during cardiopegic induction (360 seconds) but exhibited low postoperative day 1 cardiac enzymes. Low cardiac postoperative enzymes were further observed in one patient operated on for aortic dissection in which cardioplegia was directly infused in left coronary ostium due to grade 2-3 aortic valve insufficiency. High enzyme levels were observed in a patient presented with preoperative acute myocardial infarction after a failed PCI. Conclusion: Initial results with the use of HTK-cardioplegia were satisfactory in patients undergoing complex cardiac operations. Further evaluation in a larger group of patients with comparison to other established methods of myocardial protection is warranted to confirm this positive early experience.