Abstract
A 62-year-old male with symptomatic persistent atrial fibrillation underwent radiofrequency catheter ablation. During exchange of the saline irrigation bag, the patient developed sudden hypotension and bradycardia and was found to have a massive air embolism. Air was successfully aspirated with catheters, and the patient did not suffer any permanent sequelae. (Level of Difficulty: Intermediate.)
Key Words: air embolism, atrial fibrillation, catheter ablation
Abbreviations and Acronyms: AF, atrial fibrillation; LAA, left atrial appendage; LV, left ventricle; RCA, right coronary artery
Graphical abstract
A 62-year-old male patient with hypertension received a diagnosis of persistent atrial fibrillation (AF) after developing dyspnea on exertion. He was started on apixaban and metoprolol. He underwent 2 electrical cardioversions but only briefly maintained sinus rhythm. He was reluctant to take antiarrhythmic medications and was referred for catheter ablation. Pre-procedural cardiac magnetic resonance imaging showed mildly enlarged left atrium with normal cardiac function.
Learning Objectives
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To be able to make a differential diagnosis for sudden hypotension and bradycardia during cardiac catheter ablation for atrial fibrillation.
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To identify the causes of air embolism and the clinical manifestation of air embolism.
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To be able to rapidly formulate a treatment plan for massive air embolism.
On the day of the ablation procedure, the patient presented in AF with average heart rate of 65 beats/min. Following induction of general anesthesia, transesophageal echocardiography confirmed no left atrial appendage (LAA) thrombus, bilateral femoral venous access (two 8-F sheaths in the right femoral vein exchanged for long sheaths positioned in the left atrium (9-F and 7-F sheaths in the left femoral vein) was obtained. A 5-F sheath was placed in the right femoral artery. Heparin was given (90 U/kg for a total of 8,000 U, followed by 1,000 U/h drip) to maintain activated clotting time 300 to 350 ms. Double transseptal punctures using a Brockenborough-1 needle (St. Jude Medical, St. Paul, Minnesota) were performed, using intracardiac echocardiographic and fluoroscopic guidance, with confirmation of left atrial positioning by visualization of contrast injection and pressure tracing. Both long sheaths (Agilis and SL-0, St. Jude Medical) were continuously irrigated with heparinized saline infused at 180 ml/h. Through the long sheaths, a circular mapping catheter (Optima, St. Jude Medical) and an irrigated contact force-sensing radiofrequency ablation catheter (Tacticath, St. Jude Medical) were advanced into the left atrium.
Circumferential ablation was performed at 25 to 35 W, a temperature cutoff of 42°C, a goal contact force of 10 to 20 g, and a minimal force time integral of 400 g-s.
After 58 ablation lesions, the ablation catheter saline irrigation bag was empty, and the irrigation pump alerted to the presence of air within the tubing; a new saline bag was attached. A stopcock was opened to flush the system, and the priming function was resumed. Shortly afterward, the patient suddenly became hypotensive and bradycardic.
Medical history
The patient had a history of hypertension and persistent AF.
Differential diagnosis
The differential diagnosis for sudden hypotension and bradycardia during AF ablation procedure included an exaggerated vagal response to ablation of a ganglionated plexus near the pulmonary vein; pericardial effusion from perforation during transseptal access or ablation; or air/thromboembolism entering the right coronary artery (RCA). Anaphylactic reactions to contrast or other medications, including anesthetic agents, are also on the differential.
Investigations
Electrocardiography showed ST-segment elevation in the right precordial and inferior leads (Figure 1). Fluoroscopy showed a large amount of air in the LAA, left ventricular (LV) apex, and aortic root (Figure 2, Video 1). Intracardiac echocardiography showed no pericardial effusion. Given the timing of the patient’s sudden deterioration, air embolism was clearly the cause. Subsequently, it was found that the stopcock leading to the Agilis sheath transseptal flush had been closed to the patient, whereas the stopcock on the ablation catheter remained opened to the patient (Figure 3A); hence, air in the irrigation line was flushed into the left heart.
Figure 1.
Baseline Electrocardiogram Versus Electrocardiogram During Air Embolism
Baseline 12-lead electrocardiogram at the start of the ablation procedure in atrial fibrillation shows normal QRS complex and ST-segments. Following the occurrence of an air embolism, there is marked ST-segment elevation in the right precordial and inferior leads (leads III > II), suggesting a right ventricular and inferior left ventricular injury pattern. Atrial pacing was performed, given initial sinus bradycardia.
Figure 2.
Massive Air Embolism in the Left Ventricular Apex and Ascending Aorta
RAO and LAO views show an area of radiolucency caused by air in the left atrial appendage, left ventricular apex, and ascending aorta, as denoted by the dotted yellow line. Ao = aorta; Circ = circular mapping catheter; CS = coronary sinus catheter; Eso = esophagus (with barium); ICE = intracardiac echocardiogram catheter; LAO = left anterior oblique; LV = left ventricle; PT = pulmonary trunk; RA = right atrium; RAO = right anterior oblique; RF = radiofrequency ablation catheter; RV = right ventricle.
Figure 3.
Irrigation Line Schematic
Sheaths and catheters in the left atrium are shown through a transseptal approach. (A) The root cause of air embolism. Multiple unlabeled, tangled irrigation lines made it easy to mistakenly close the deflectable sheath (Agilis) stopcock, leaving the ablation irrigation line stopcock open during the priming function. (B) An ideal setup with clearly labeled lines and 2 saline bags for ablation irrigation.
The patient’s pupils were also noted to be asymmetrical (6 mm on the left, 2 mm on the right) but reactive to light bilaterally.
Management
A 5-F Judkins Left (JL4) catheter (Merit Medical OEM, South Jordan, Utah) was advanced into the ascending aorta, and air was aspirated (Figure 4A). The ablation catheter was replaced sequentially with a 5-F pigtail (Figure 4B, Video 2) and then a 7-F Berman angiographic catheter (Teleflex Inc, Morristown, North Carolina). These catheters were advanced into the LAA and LV apex using the transseptal approach, and aspiration was performed until there was no further air visualized on fluoroscopy and transesophageal echocardiography (Figure 4C). Coronary angiography showed no air in the coronary arteries. All ST-segment elevations, as shown on electrocardiography, had resolved after approximately 15 min. Hyperbaric oxygen therapy was considered, but following cerebral angiography, no air was shown in any of the cerebral vessels, so it was decided to wake the patient up from anesthesia.
Figure 4.
Aspiration of Air From the LV and Ascending Aorta
(A) Successful aspiration of air from the ascending aorta with a 5-F JL4 catheter. (B) A 5-F pigtail catheter advanced into the LV apex to aspirate air. (C) The final image after the use of a Berman catheter in the LV apex showsall air successfully aspirated. LV = left ventricle; TEE = transesophageal echocardiogram.
No further ablation was performed. Protamine was given, and all sheaths and catheters were removed. His neurologic examination results upon awakening was normal. Transthoracic echocardiography performed the following day showed normal LV ejection fraction and wall motion. He had no procedure-related sequalae at 1-month follow-up.
Discussion
Air embolism is a well-known but infrequent complication of cardiac catheterization procedures. It generally presents as transient (average: 5 min) ST-segment elevations in the inferior leads with simultaneous bradycardia and hypotension due to RCA occlusion. It is safe to proceed with the procedure after complete resolution (1).
Rarely, however, massive air embolism can result in severe hemodynamic alterations and even cardiopulmonary arrest due to complete RCA occlusion or obstruction to blood flow. Maintaining the patient in a supine or Trendelenburg position is paramount to avoid cerebral air embolism, as air will accumulate in the anterior cardiac structures. Aspiration of air directly from the RCA has previously been described by Ahmad et al. (2). Kuwahara et al. (3) reported that forceful injection of contrast or saline into the RCA could also fragment large occlusive air bubbles. Kuwahara et al. (3) also described aspiration of air from the LAA. In the present case, it was shown that massive air embolism in the LAA, LV, and aorta can be successfully aspirated with catheters.
Careful technique to avoid air embolism is crucial in all left-sided cardiac catheterization procedures. However, unintended equipment failures such as damage to the sheath diaphragm (4) or entrapment of air from deep breaths and negative intrathoracic pressures during insertion of catheters (3) can still occur. The CoolPoint (St. Jude Medical) irrigation system has 2 bubble sensors which immediately shut off irrigation and ablation if air bubbles are found within the tubing. However, during the priming function, the bubble sensors are switched off. Human error (i.e., closing the wrong stopcock) was the root cause of the present complication. Avoiding such complications requires recognition of this potential complication, and protocols requiring multiple laboratory staff to confirm correct procedure when flushing an irrigated catheter situated in the body. Maintaining 2 saline bags for ablation catheter irrigation, protocols for regular checks on remaining bag volume, and color-coding tubing flushing into the left heart can also help.
With rapid recognition and prompt treatment, massive air embolisms can be managed successfully with no permanent sequelae.
Follow-up
The patient underwent event monitoring at 3- and 6-months post-ablation, both of which showed sinus rhythm and no arrhythmias.
Conclusions
This paper describes a case of massive air embolism that occurred during an AF ablation procedure due to inadvertent flushing of air through the ablation catheter irrigation line into the left heart. Rapid aspiration of air from the ascending aorta and LV apex was performed. The patient did not experience any permanent sequelae. Catheterization laboratory protocols to avoid air embolism during saline irrigation bag exchanges are necessary to avoid this potentially catastrophic complication.
Author Disclosures
Dr. Do is supported by a grant from the Rosanne Silbermann Foundation. Dr. Shivkumar is supported by U.S. National Institutes of Health grants R01HL084261 and U01EB025138. Dr. Boyle has received speaking honoraria from Janssen Pharmaceutical. Dr. Bradfield has received speaking honoraria from Abbott and Boston Scientific. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
Roderick Tung, MD, served as Guest Editor for this paper.
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos, please see the online version of this paper.
Appendix
Air embolism. Fluoroscopy of an air embolism in the ascending aorta, left ventricular apex, and left atrial appendage.
Air embolism aspiration. Fluoroscopic video of aspiration of the air embolus in the left ventricular apex using a pigtail catheter.
References
- 1.Tang R.-B., Dong J.-Z., Long D.-Y. Incidence and clinical characteristics of transient ST-T elevation during transseptal catheterization for atrial fibrillation ablation. Europace. 2014;17:579–583. doi: 10.1093/europace/euu278. [DOI] [PubMed] [Google Scholar]
- 2.Ahmad K., Asirvatham S., Kamath S., Peck S., Liu X. Successful interventional management of catastrophic coronary arterial air embolism during atrial fibrillation ablation. HeartRhythm Case Rep. 2015;2:153–156. doi: 10.1016/j.hrcr.2015.12.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kuwahara T., Takahashi A., Takahashi Y. Clinical characteristics of massive air embolism complicating left atrial ablation of atrial fibrillation: lessons from five cases. Europace. 2011;14:204–208. doi: 10.1093/europace/eur314. [DOI] [PubMed] [Google Scholar]
- 4.Voci P., Yang Y., Greco C., Nigri A., Critelli G. Coronary air embolism complicating accessory pathway catheter ablation: detection by echocardiography. J Am Soc Echocardiogr. 1994;7:312–314. doi: 10.1016/s0894-7317(14)80402-1. [DOI] [PubMed] [Google Scholar]
Associated Data
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Supplementary Materials
Air embolism. Fluoroscopy of an air embolism in the ascending aorta, left ventricular apex, and left atrial appendage.
Air embolism aspiration. Fluoroscopic video of aspiration of the air embolus in the left ventricular apex using a pigtail catheter.