Background

Cardioplegia is delivered via antegrade, retrograde, or combined perfusion routes. Antegrade cardioplegia follows the physiological path but may be less effective in patients with severe coronary disease. Retrograde delivery allows continuous surgical manipulation but may result in uneven myocardial protection. This study compared myocardial cooling effects across delivery methods using thermographic imaging.

Methods

Of 221 open-heart surgeries at our institution between May 2020 and November 2023, 22 cases with thermographic myocardial temperature data were retrospectively analyzed. All procedures were performed using blood cardioplegia (MPS®2, Quest. Medical, Inc.) Twenty-two patients initially received antegrade cardioplegia. For the second dose, they were divided into Group A (antegrade, n = 10) and Group R (retrograde, n = 12). Myocardial surface temperatures were assessed at multiple time points using thermography.

Results

At the start of initial cardioplegia, myocardial surface temperatures were 31.6 ± 0.7°C in Group A and 31.8 ± 1.4°C in Group R, with infusion volumes of 2050 ± 396 mL and 2072 ± 251 mL, respectively; differences were not significant. Following the first dose (20°C cardioplegia), temperatures dropped to 22.7 ± 0.8°C and 23.8 ± 1.6°C, respectively, with no significant difference due to identical delivery. At the second dose, temperatures were 27.6 ± 1.2°C in Group A and 28.8 ± 1.7°C in Group R. After the second dose, Group A showed significantly lower temperatures (22.7 ± 0.6°C) compared to Group R (24.6 ± 1.9°C, p < 0.05). No intergroup differences were seen in postoperative ejection fraction, creatine kinase, catecholamine use, extubation time, hospital stay, or overall clinical outcomes. Cardiac function was preserved in both groups.

Conclusion

While retrograde cardioplegia facilitates uninterrupted procedures, it may be less effective for myocardial cooling, raising concerns about protective adequacy. Thermography offers a practical, noninvasive means to assess myocardial temperature and detect insufficient cooling, enhancing myocardial protection strategies.