Author + information
- Jian-Fang Ren, MD∗ (, )
- David J. Callans, MD and
- Francis E. Marchlinski, MD
- ↵∗University of Pennsylvania Health System, 111 North 9th Street, Philadelphia, Pennsylvania 19107-2452
We read with great interest the report by Berti et al. (1). We agree with their view point that intracardiac echocardiography (ICE) imaging can perform the tasks typically provided by transesophageal echocardiography (TEE) during transcatheter occlusion of the left atrial (LA) appendage (LAA). Although the authors presented utility and safety assessment of ICE-guided percutaneous LAA device closure (Amplatzer cardiac plug) in a relatively large cohort of 120 patients, there were several issues in methodology that need to be clarified and discussed.
Ideal ICE imaging views and accurate measurement of the LAA anatomy including the ostium, short- and long-axes, and the landing zone are critically important for proper sizing and delivery. Although they failed to present a uniform ICE examination protocol, they describe imaging the LAA with the transducer in the right atrium (RA) and coronary sinus (CS). In majority of the atrial fibrillation patients with LA enlargement, the RA transducer view does not provide anatomically detailed LAA imaging with sufficient resolution due to far-zone imaging features. The authors try to argue against this with a “best example” figure (Figure 2 ), but it appears that the transducer in this figure is actually in the LA because the interatrial septum is not imaged. In addition, when imaging from the CS, the LAA is often truncated, and it is difficult to obtain an ideal LAA ostium and LAA long-axis image due to the limited potential for transducer manipulation in the narrow CS lumen.
In our experience using ICE for cardiac diagnosis and left heart ablation in more than 3,000 cases, specific imaging views routinely provide important LAA anatomic features as part of a complete assessment (2). A transverse long-axis image of LAA with its orifice can be typically obtained with the transducer placed in the right ventricular outflow tract (RVOT). This imaging view is especially helpful for anatomic assessment and LAA size measurements (Figure 1A). Close-up imaging using higher ultrasonic frequency can be obtained with the transducer placed in the pulmonary artery (PA). These imaging views are especially helpful for differentiation of thrombus from variant pectinate muscles/sluggish flow and to properly image/measure LAA emptying flow (Figure 1B). Peripheral LAA–left ventricle imaging views can also be obtained with the transducer placed in PA for close-up evaluation of lobes and pectinate muscles (2). Therefore, the best view for measurement of the anatomy of the LAA is the ICE transducer placed in the RVOT. The LAA ostium is usually measured from the LAA junction with the upper left pulmonary vein (ULPV) ostium to the junction of the LA and LAA (Figure 1A). The landing-zone diameter can be accurately determined with a certain distance to the ostium. In addition, this view also provides the best imaging to guide proper sheath/device placement in the LA to LAA ostium, much better than the ideal lobe for sheath placement that was decided on based on fluoroscopic images indicated by the authors (1).
Another important issue is to evaluate/eliminate any peridevice leak immediately after device implantation. The leak flow could not be accurately detected with the ICE RA or CS transducer due to sampling difficulty for parallel flow. The peridevice leak can be detected using color Doppler flow imaging, especially for LAA emptying leak flow in a close-up view with the ICE transducer positioned in the PA (3).
Of note, echocardiographic imaging measurement of the soft structural distance has been recognized as one of the most accurate methods. Echocardiographic distance measurement is much more reliable and accurate than fluoroscopic imaging, even with contrast. However, it is not possible that the ICE and TEE measurements of the ostium and landing zone were the same in 78.4% of the cases (1). From their Figure 6 (1), there were significant differences in anatomic landmarks selected for the LAA ostium and landing zone measurements between ICE and TEE. For the TEE measurements, the LAA ostium and landing zone were measured from the LAA junction with the ULPV ostium to the junction of LA and LAA (at mitral annulus, left panel Figure 6 ), whereas for ICE (CS transducer), these measurements seemed arbitrary without any strictly defined anatomic marks (right panel, Figure 6 ). Our previous measurements of LAA anatomy including long and short axes have shown a difference between ICE and TEE, even following similar anatomic landmarks (2).
The investigators should be congratulated for reporting on a relatively large cohort of patients who underwent LAA device closure. Although ICE has many advantages in interventional procedures, the methodology was not uniform and did not use the optimal transducer positions. These difficulties impair the power of this study and put into question the accuracy of their conclusions.
- 2015 American College of Cardiology Foundation
- Berti S.,
- Paradossi U.,
- Meucci F.,
- et al.
- Ren J.F.