An 87-year-old man with atrial fibrillation, high thromboembolic risk, and history of dense spontaneous echo contrast (SEC) in the left atrial appendage (LAA) despite oral anticoagulation therapy was considered for transcatheter left atrial appendage closure (LAAC). Pre-procedural transesophageal echocardiography (TEE) demonstrated dense SEC in the LAA that had not cleared despite changes in his anticoagulant medications (Figure 1A). After infusion of isoproterenol at 2 μg/kg/min for 5 min, there was resolution of SEC and no LAA thrombus was identified (Figure 1B, Online Videos 1 and 2). LAA velocity measured by pulsed-wave Doppler did not change substantially from pre-infusion to peak infusion (10.7 cm/s vs. 10 cm/s, respectively). The patient underwent successful LAAC without complication.
FIGURE 1. Resolution of LAA Smoke After Administration of Isoproterenol.
(A) Transesophageal echocardiogram demonstrating smoke in the left atrial appendage (LAA), which is concerning for possible thrombus. (B) Transesophageal echocardiographic imaging after 5-min infusion of isoproterenol, which demonstrates no evidence of LAA thrombus. See Online Videos 1 and 2.
Previous studies have used isoproterenol in post-electrical cardioversion to overcome myocardial stunning and increase LAA emptying velocity (1). The exact mechanism of action for SEC clearing from the LAA post-isoproterenol remains unclear. The LAA velocity measured by pulsed wave Doppler did not change significantly in our case. There may be a more effective measure of flow or contractility for the LAA. The observation that peak LAA velocity did not change in this case may be consistent with a more severe LAA myopathy or may be consistently associated with atrial fibrillation. Although a theoretical risk exists for embolization, previous studies have demonstrated increased LAA velocity with isoproterenol or pacing however, no change was noted in the setting of atrial fibrillation (2). Our patient underwent an uneventful procedure but further investigation is required to determine whether isoproterenol infusion can be safely used to distinguish SEC from thrombus during LAAC.
Supplementary Material
Acknowledgments
Dr. Pandey has received support from a National Institutes of Health National Center for Advancing Translational Sciences Clinical and Translational Science Award to Scripps Research (KL2TR002552), and a Scripps Translational Science Institute Pilot Award (UL1TR002550). Dr. Olson has received consulting fees and other honoraria from Medtronic, Abbott Medical, and Biosense Webster. Dr. Price has received consulting and speaker’s honorarium from Boston Scientific and Medtronic; has received speaker honorarium from Abbott Vascular; and has received research/grant support from Daiichi-Sankyo. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
APPENDIX For the supplemental videos, please see the online version of this paper.
All 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 JACC: Clinical Electrophysiology author instructions page.
REFERENCES
- 1.Date T, Takahashi A, Iesaka Y, et al. Effect of low-dose isoproterenol infusion on left atrial appendage function soon after cardioversion of chronic atrial tachyarrhythmias. Int J Cardiol 2002;84:59–67. [DOI] [PubMed] [Google Scholar]
- 2.Sanders P, Morton JB, Morgan JG, et al. Reversal of atrial mechanical stunning after cardioversion of atrial arrhythmias: implications for the mechanisms of tachycardia-mediated atrial cardiomyopathy. Circulation 2002;106:1806–13. [DOI] [PubMed] [Google Scholar]
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