It is very uncommon, but possible for air to be introduced into the left atrium during cardiac conduction pathway ablation procedures. If that air embolus should transit into a coronary artery the signs and symptoms of acute coronary artery occlusion may occur.
Dr. Mandel notes that coronary air embolus is a rare complication outside of the cardiac ORs. Patients in the heart room are generally intubated and ventilated with 100% oxygen, but patients experiencing this complication in out-of-OR locations are frequently breathing room air. While certainly not the only measure to be taken during such an event, prompt denitrogenation is an important intervention. Use of a Mapleson system with high fresh gas flow and a good seal should be considered as an important first step in responding to this event. Treatment review paper attached.
Dr. Eckmann provides further detail: 1) if the gas bubble is accessible to an interventional catheter already in situ, attempts should be made to aspirate the bubbles. 2) Once they have lodged, it is very difficult to dislodge bubbles to push them distally. 3) Once bubbles are in and stuck, there is very little that can be done to alter the adhesion that has developed between the bubble and endothelial cell surface. So nothing injectable is helpful at this point, though there may be some rationale to try to dilate the coronary vasculature locally to dislodge bubbles and permit them to flow distally. 4) It is therefore necessary to alter gas adsorption to enhance the rate at which gas exits the bubble and becomes solubilized in surrounding tissue. My experimental and computational/theoretical work has shown that microvascular bubbles as small as a few nanoliters in volume can survive for 20-30 min, and larger bubbles may last for hours! So changing the partial pressure gradients (essentially, the concentration gradients) in surrounding tissues enhances the driving force for gas to exit the bubbles. This can only be accomplished by two methods: change the breathing gas admixture (decrease nitrogen, especially if the bubble is at all composed of nitrogen) and increase the ambient pressure. Placing the patient on 100% oxygen or initiating hyperbaric therapy are both appropriate steps. Clearly placing the patient on 100% oxygen can be quickly started while other therapy is arranged.
Injection of contrast agent directly into the affected vessel may also help solubilize the gasses in the embolus.
Jeff Mandel M.D. is Clinical Associate Professor of Anesthesiology and Critical Care
David Eckmann M.D. is Associate Professor of Anesthesiology and Critical Care