Randomized trial of HTK versus warm blood cardioplegia for right ventricular protection in mitral surgery

OBJECTIVES: To clarify the reliability of the one-shot histidine-tryptophane-ketoglutarate (HTK) cardioplegia for right ventricular (RV) myocardial protection during mitral surgery, in patients with or without pre-operative RV dysfunction. DESIGN: Sixty patients undergoing isolated mitral surgery were randomized to myocardial protection with either one-shot HTK or intermittent warm blood cardioplegia (WBC). The RV function was assessed by echocardiography and hemodynamic assessment. Pre-operative tricuspid annular plane systolic excursion (TAPSE), an index of RV systolic function was used to dichotomize groups into patients having impaired (TAPSE < 15) or preserved (TAPSE ≥ 15) RV function. RESULTS: There were no significant intergroup differences in the post-operative indexes of RV function in cases with TAPSE ≥ 15. In patients having TAPSE < 15 we observed statistically worse RV ejection fraction (RVEF, 15% ± 2% vs. 24% ± 3%), end-diastolic volume (RVEDV, 188 mL ± 20 vs. 179 mL ± 14) and fractional area change (RVFAC, 21% ± 6% vs. 30% ± 3%) after use of the HTK solution versus patients who received the WBC. These differences were associated with longer mechanical ventilation and ICU times in patients with impaired RV function and receiving HTK cardioplegia. In a substudy ten patients with TAPSE < 15 received intra-operative topical myocardial cooling in addition to HTK. The addition of topical cooling to HTK cardioplegia yielded statistically significant amelioration in post-operative RV function compared with patients who received the HTK solution without topical cooling (RVEF: 23% ± 3% vs. 15% ± 2%; RVEDV: 180 mL ± 9 vs. 188 mL ± 18; RVFAC: 8.5% ± 1% vs. 6% ± 2%). CONCLUSIONS: The one shot HTK solution offers inferior RV protection compared with WBC, mainly in patients with depressed pre-operative RV function. When adopting HTK cardioplegia the addition of topical cooling is strongly advised.