Staged systemic hyperkalemia and deep hypothermia for myocardial protection in mini-thoracotomy reintervention: Preserving patency in post-CABG patent grafts

Abstract

Background

Traditional cardioplegia strategies often fail in cases with patent coronary grafts due to continuous myocardial perfusion, this necessitates for alternate approaches such as systemic hyperkalemic cardiac arrest. During redo cardiac surgeries, a patent left internal mammary artery (LIMA) might prevent the heart from maintaining electrical cardiac arrest. Induced systemic hyperkalaemia is a novel approach to maintain cardiac electromechanical arrest.

Case summary

We report a case of 66 year-old male with a history of Post CABG for Triple vessel disease (TVD) who required mini-thoractomy for left atrial myxoma excision. Given the existence of patent coronary grafts, attaining cardiac arrest with standard cardioplegia was not possible, necessitating the use of systemic hyperkalaemia for myocardial arrest. The patient was placed on Femoro-femoral cardiopulmonary bypass (CPB) and cooled to 20°C. To induce myocardial arrest, multiple potassium boluses were delivered, totalling 120 mEq/L potassium chloride (KCl) over multiple stages. Despite high potassium levels (6.7 mEq/L in the third arterial blood gas), CPB was successfully weaned off, and the surgical recuperation went smoothly. This case highlights the complexities of myocardial protection in redo cardiac surgery and underscores the role of systemic hyperkalaemia, perfusion management, ultrafiltration, and careful electrolyte management in such high-risk settings. To the best of our knowledge this is the first documented case report of its kind internationally. While there are previous reports of left atrial myxoma excision in post-CABG patients, including those managed using ventricular fibrillation, this is the first reported case in which systemic hyperkalemia combined with deep hypothermia was successfully utilized via a mini-thoracotomy approach in a post-CABG patient with a patent LIMA graft, without the use of aortic cross-clamping or ventricular fibrillation.

Conclusion

This case shows the complexities of myocardial protection in redo cardiac surgeries with patent grafts. The use of systemic hyperkalemia is a viable but challenging alternative to cardioplegia, requiring meticulous potassium management and close hemodynamic monitoring.