Episode #318 Air Embolism Alert

Opening Clip: If you provide anesthesia care for patients undergoing structural heart interventions, then it’s time to turn up the volume because we are talking about the FDA’s 2025 Early Alert for the risks of air embolism associated with the WATCHMAN Access System used for left atrial appendage occlusion procedures. There are important concern directly related to the type of anaesthetic used during this procedure. With more procedures being done under sedation, the negative intrathoracic pressure during spontaneous ventilation has been implicated in catastrophic air embolism events especially with transeptal procedures.

Hello and welcome back to the Anesthesia Patient Safety Podcast. I’m your host, Alli Bechtel. Here are the big takeaways from today’s show to support periprocedural safety for anesthesia professionals during minimally invasive heart procedures with a risk of air embolism:

1. For ventilation strategy, consider controlled positive pressure ventilation for higher-risk patients to avoid negative intrathoracic pressure using PEEP as appropriate.
2. Remain vigilant during sheath manipulation, monitor airway pressures, hemodynamics, and echocardiographic views.
3. Establish clear roles for sheath control, flushing, and line management before starting the procedure.
4. Be prepared to recognize and treat air embolism immediately with Trendelenburg positioning, hemodynamic support, aspiration if indicated, and activation of perfusion support teams if available.
5. For continuous improvement, stay current with FDA alerts, registry data, and device updates, participate in multidisciplinary reviews and simulation of rare events.

Before we dive further into the episode today, we’d like to recognize Nihon Koden, a major corporate supporter of APSF. Nihon Koden has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Nihon Koden – we wouldn’t be able to do all that we do without you!”

Our featured article is “Air Embolism During Left Atrial Appendage Occlusion (LAAO) Procedures: Lessons From the FDA Early Alert” by Daniel McGrail and colleagues. This is a APSF Newsletter Article that was published online April 1, 2026. To follow along with us, head over to APSF.org and click on the Newsletter Heading. The first one down is Newsletter articles. Then, you can scroll down until you get to our featured article, and I will include a link in the show notes as well.

And now, let’s get into the article and we’re starting with some background information. Structural heart disease procedures like transcatheter aortic valve replacement, transcatheter edge-to-edge repair, and left atrial appendage occlusion have come along way in the past 10 years with advanced technology leading to shorter hospital length of stay and no increase in complications or mortality. The anesthesia for these procedures has evolved as well moving from general anesthesia with an endotracheal tube to monitored anesthesia care with mild or moderate sedation. The decision between sedation and general anesthesia depends on many factors including proceduralist experience and patient co-morbidities, but there are additional considerations including availability of anaesthesiology resources, operating room block times, or the use of transoesophageal echocardiography. Recent studies have evaluated the differences between general anesthesia and sedation have found for sedation when it comes to hospital length of stay and mortality. Sedation may be associated with faster recovery time and decreased resource use, but there are special physiologic and procedural safety risks associated with spontaneous ventilation during sedation when air may be introduced into the heart.

Now, let’s look at the left atrial appendage occlusion procedure that seals off the left atrial appendage for patients with non-valvular atrial fibrillation who can’t take long-term anticoagulants. The stroke risk reduction from this procedure has been shown to be comparable to warfarin in all major trials. For the 6 months following the procedure, the all-cause risk of stroke and death is 1.2 and 4% respectively. We are talking about this procedure as a threat to patient safety because in August 2025, the United States Food and Drug Administration, the FDA, issued an Early Alert that highlights a serious hazard associated with the access system for one of the left atrial occlusion devices, the WATCHMAN. There were multiple cases of catastrophic air embolism during WATCHMAN procedures that were performed under sedation with spontaneous ventilation. The alert includes important considerations to help reduce the risk of air entrainment and air embolism. This is a call to action for all anesthesia professionals providing anesthesia care for patients undergoing WATCHMAN procedures. Check out Figure 1 in the article for a picture of a proceduralist holding the delivery sheath connected to a Tuohy-Borst haemostatic valve with side-port stopcock. There is a pigtail catheter going through the valve to access the left atrium. During the device exchange, the connection is kept submerged under sterile water in a basic while the system is briefly disconnected to attach the Watchman delivery device. You can also watch the supplementary video to see this happen live.

Here are the key findings from the FDA Early Alert. There were 120 known cases of serious injuries and 17 deaths related to air embolisms during left atrial appendage occlusion WATCHMAN procedures. In the national registry, the rates of air embolism during WATCHMAN procedures ranges between 0.03% and 0.06%. We also need to keep in mind that many air embolism events may be undetected. The WATCHMAN procedures and any percutaneous heart procedures with transeptal puncture to access the left atrium are particularly high risk for air embolism when you have a spontaneously ventilating sedated patient leading to an increased risk of negative pressure in the left atrium and subsequent air entrainment. Risk factors for intracardiac air entrainment during these procedures include the following:

• Spontaneous ventilation
• Upper airway collapse or obstructive sleep apnoea
• Hypovolemia predisposing to lower left atrial pressures
• Inadequate de-airing of the access system
• Accidental injection of air.

The important steps when air can be introduced into the left atrial appendage occlusion access system are if the sheath or valve system is exposed to open air, inadequately de-aired, or positioned above the level of the heart during spontaneous ventilation. In order to access the left atrium, a transeptal puncture is made with a 14Fr catheter and if air is entrained through this device, it has a direct path to the left atrium. Patients are at risk for coronary air embolism and you may see ST-segment changes,  hemodynamic instability, and wall motion abnormalities as well as cerebral air embolism leading to stroke.

Let’s turn our attention to Table 1 and some suggestions provided by the FDA for risk mitigation to help prevent air entrainment during minimally invasive cardiac procedures and this is especially important when there is a transeptal puncture.

1. Hemodynamic Optimization and maintenance of euvolemia before puncture to avoid negative left atrial pressures.
2. Device handling with all sheaths, stopcocks, and access valves kept below the level of the heart and filled with fluid.
3. Careful de-airing of all access systems by flushing lines slowly and maintaining a continuous fluid column during device exchanges.
4. Exchange protocol with all sheath and wire exchanges performed under a saline or water bath, slow device withdrawal, and made during expiration for spontaneously ventilating patients.
5. System Readiness with confirmation of air elimination and valve seals before insertion. Clear communication between cardiology and anesthesia professionals in a vital step prior to each exchange as well.

Now, we’re going to run through the list of safety principles for anesthesia professionals involved in minimally invasive heart procedures with risk of air embolism. The next time you are providing anesthesia care in the interventional cardiology suite, we hope that these principles will help guide your management as well as provide insights for important systems-level considerations that are needed to help keep patients safe and continuing to keep patients safe in the future.

1. For ventilation strategy, consider controlled positive pressure ventilation for high-risk patients including those with obstructive sleep apnoea to avoid negative intrathoracic pressure and use PEEP as appropriate for the patient.
2. For monitoring and awareness, maintain situational awareness during sheath manipulation, monitor airway pressures, hemodynamics, and echocardiographic views.
3. For team communication, establish clear role assignments for sheath control, flushing, and line management before starting the procedure.
4. For immediate response preparedness, be ready to recognize and treat air embolism with Trendelenburg positioning, hemodynamic support, air aspiration if indicated, and activation of the perfusion support team.
5. For continuous improvement, it is important to stay current with FDA alerts, registry data, and device updates. It is important for your team to participate in multidisciplinary reviews and simulation of rare events.

We can see that there is a risk of air embolism during these procedures, but what is it about sedation that increases this risk? During sedation and spontaneous ventilation, negative intrathoracic pressure creates a suction gradient that favours air entry into open or inadequately sealed vascular systems. Plus, we are talking about the left atrium here and even small amounts of air can procedure serious cerebral or coronary embolic events. This suction force is not produced when patients are under general anesthesia with positive pressure ventilation. The positive-pressure helps to create a protective outward pressure gradient to help decrease the risk for air embolism. Just all many things in anesthesia though, we need to weigh the risks and benefits – the benefit of positive pressure ventilation and decreasing the risk for air embolism compared to the risks of general anesthesia, procedural, and patient risk factors. There is a call to action for awareness of the physiology and closed loop communication with the procedural team anytime there is a transseptal puncture and the mode of ventilation changes the pressure gradient across the open cardiac access system.

Air embolism during interventional cardiac procedures is not new and has been studied in the electrophysiology or EP lab. So, let’s head next door and see what the literature from EP and pulmonary vein isolation for the treatment of atrial fibrillation reveals. Catheter ablation for pulmonary vein isolation may involve cryoballoon ablation, radiofrequency ablation, or pulse field ablation and may be performed under general anesthesia or sedation. There was a prospective, multicentre study of about 1000 patients comparing sedation with general anesthesia and showed no difference in neurological events. In addition, a recent meta0analysis compared recurrence of atrial tachyarrhythmias with sedation or general anesthesia and found no differences in the recurrence rate or complications. The rates of air embolism during atrial fibrillation ablation procedures may be as high as 1.5% with air entrainment during ablation and mapping catheter utilization. Contributing factors include sheath/catheter size mismatch, catheter tip shape, design of the haemostatic valve. Pulse field ablation sheaths now have clear shafts so that air bubbles can be visualized by operators. Mitigation strategies during these EP procedures include monitoring all infusion lines for bubbles and slow removal of all catheters with simultaneous aspiration. Other techniques may include using sheath-in-sheath which involves leaving a smaller inner sheath inside the transseptal sheath at all times during exchanges with a continuous saline drip to prevent air entry during catheter exchange. Decreasing the risk for air entry may also be accomplished with slow flushing of sheaths, temporary balloon inflation prior to insertion, or carrying out sheath access under a water bath. I’ll include the citations for this EP literature review in the show notes as well.

As we wrap up for today, here are the important take aways and action items:

• Establish clear sedation and general anesthesia criteria that account for patient and physiologic risk due to the procedure.
• Oversight and competency training may be required for any updated procedural steps.
• Consider implementation of procedural checklists (you know we love checklists!!) for de-airing and sheath positioning to improve reliability over time.
• Enable and empower all health care professionals to speak up about compliance with safety procedures.
• Report any adverse outcomes or device failures to the FDA for all suspected device-related adverse events.

We made it to the end of the article. If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today. Remember, anesthesia professionals can help identify physiologic and procedural hazards before harm occurs. Any cardiac procedure with transseptal puncture carries serious risk for air embolism and keeping patients safe depends on multidisciplinary collaboration and team work.

Calling all researchers! Applications are now open for the Foundation for Anesthesia Education and Research Fall 2026 Grant Cycle. Now, through August 15, 2026. Grants available include the Mentored Research Training Grant, Research in Education Grant, and Research Fellowship Grant. The Transition to Independent Grant is also available on a rolling basis. Head over the FAER.org/Grants for more information and check out the link in the show notes.

Thanks for joining us for another episode of the Anaesthesia Patient Safety Podcast. We hope today’s conversation has given you practical insights to help make anaesthesia even safer for every patient in the interventional cardiology suite, EP lab, or just the general operating rooms…and given you the inspiration to apply for one of the grants that we talked about.

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Until next time, stay vigilant and stay informed so that no one shall be harmed by anesthesia care.

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