Anesth Analg 2003;96:1584-1588
© 2003 International Anesthesia Research Society
CARDIOVASCULAR ANESTHESIA
Supplementing Transesophageal Echocardiography with Transthoracic Echocardiography for Monitoring Transcatheter Closure of Atrial Septal Defects with Attenuated Anterior Rim: A Case Series
Su-Man Lin, MD*,
,
Shen-Kou Tsai, MD PhD*,
,,
Jou-Kou Wang, MD PhD
,,
Yin-Yi Han, MD*,,
Wei-horng Jean, MD*,, and
Yu-Chang Yeh, MD*,
Departments of *Anesthesiology and
Pediatrics,
National Taiwan University, School of Medicine;
National Yang-Ming University, School of Medicine and Taipei Veterans General Hospital, Taipei, Taiwan
Address correspondence and reprint requests to Dr. Shen-kou Tsai, Departments of Anesthesiology, Taipei-Veterans General Hospital, National Taiwan University, and Yang-Ming University, 201, Sec. 2, Shih-pai Rd., Taipei 11217, Taiwan. Address e-mail to sktsai{at}vghtpe.gov.tw
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Abstract
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The use of transesophageal echocardiography (TEE) for guidance of transcatheter closure of secundum-type atrial septal defect (ASD) is increasingly becoming a routine procedure. ASD with attenuated anterior superior (SA) rim is a variant of secundum-type ASD and is suitable for transcatheter closure. The success rate of TEE guidance for device deployment in these patients is not known. Therefore, we assessed 124 consecutive patients with ASD (57 secundum-type, 67 with attenuated SA rim) closed with an Amplatzer Septal Occluder under TEE guidance. Our results show that the TEE was successful in depicting all 4 corners and corresponding edges of each Amplatzer disk, as well as the septal rims of all 57 secundum-type ASDs. However, in 6 of 67 ASDs (9%) with attenuated SA rim in which TEE failed to visualize the adequate placement of occluder on the anterior inferior (IA) rim, the additional use of transthoracic echocardiography helped to resolve this inadequacy. Four of these six patients had the unusual morphology of the IA rim tissue. Two had severe right axis deviation of the heart with large Q angle (>90°). The SA rim was absent in 35 of 67 ASDs with attenuated SA rim and in these cases TEE demonstrated the anterior surface of the disk against the wall of the aorta but without distortion. We conclude that TEE can be useful for confirming successful deployment of the occluder in most patients with ASDs. In a small number of ASDs with attenuated SA rim who have unusual IA morphology, supplemental transthoracic echocardiography is required to verify successful deployment of the occluder when TEE visualization fails to reliably diagnose adequate placement of the occluder.
IMPLICATIONS: Transesophageal echocardiography can be useful for confirming successful deployment of the occluder in the majority of patients with atrial septal defect. In a small number of atrial septal defects with attenuated anterior superior rim which have unusual anterior inferior morphology, supplemental transthoracic echocardiography is required to verify successful deployment of the occluder when transesophageal echocardiography visualization fails to reliably diagnose adequate placement of the occluder.
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Introduction
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The use of transesophageal echocardiography (TEE) guidance can facilitate device placement for closure of atrial septal defects (ASDs) (1–8). ASD with an attenuated anterior superior (SA) rim (no fold beneath the ascending aorta as shown in Fig. 1a) is a morphological variation of secundum-type ASD and repair of such lesions with transcatheter closure is increasingly gaining acceptance (1). However, transcatheter closure of ASDs in such patients is hampered by increased risk of the disk impinging on the surrounding cardiac structures and/or prolapsing of the atrial disk because of a smaller supporting rim tissue. Clear demonstration of the anterior inferior (IA) rim (Fig. 1b) during device placement in those patients can diagnose this problem early and prevent the risks. However, distortion of the IA rim after disk placement will make the TEE visualization even more difficult. In 124 ASD patients with or without attenuated SA rim undergoing Amplatzer Septal Occluder (ASO), we assessed the effectiveness of TEE monitoring for visualizing the IA rim’s margin before and after ASO placement.
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Figure 1. a, Transesophageal echocardiography (TEE) image at 30° from mid-esophageal aortic valve short axis demonstrating an atrial septal defect (ASD) with attenuated anterior superior (SA) rim of defect against the aortic wall. b, Mid-esophageal four-chamber view at 0° of TEE showing ASD with posterior inferior rim and anterior inferior (IA) rim of defect. T = transducer, LA = left atrium, RA = right atrium, Ao = aorta, MV = mitral valve.
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Materials and Methods
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Patients
Approval was obtained from our Hospital’s Human Investigation Committee, and informed consents were obtained from patients or parents for the operative procedure and general anesthesia. From February 1999 to March 2002, 124 consecutive patients with ASDs with or without attenuated SA rim (rim length 
3 mm) underwent attempted ASO. The ages of the patients ranged from 3 to 48 yr with a median of 10 yr in isolated secundum ASD and from 2 to 63 yr with a median of 11 yr in ASD with attenuated SA rim.
All patients had IV access before coming to the operation room for general anesthesia. Anesthesia was induced with propofol 2.5 mg/kg IV and fentanyl 2 µg/kg. Endotracheal intubation was facilitated with atracurium 0.5 mg/kg IV. Anesthesia was maintained with an IV infusion of propofol 150 µg · kg-1 · min-1 with oxygen and supplemental atracurium used for muscle relaxation when required. The dose of propofol was adjusted up or down or supplemented depending on length of the procedure, patient movement, or vital signs.
TEE and fluoroscopy guidance were used simultaneously during all placements of the occluder device. Additional transthoracic echocardiography (TTE) was used only when TEE failed to depict adequate placement of the occluder. The catheterization procedure for deployment of the Amplatzer device is described elsewhere (4).
The Role of TEE
Under endotracheal anesthesia, all patients were placed in a supine position, and the endoscope (16 mm for adults and 9 mm for children; Vingmed Ultrasound, GE, Horten, Norway) with a 5-MHz multiplane color flow and Doppler transducer was introduced gently into the esophagus without force. The probe was always maintained in an unlocked position, with a slight flexion of the tip. Those patients with esophageal abnormalities, such as diverticuli, ulcer, or varices would have been excluded, but none was found in our series patients. In each patient, systemic multiplane TEE imaging with color flow Doppler was obtained, photographed, and analyzed before, during, and after the implantation of the Amplatzer device. A comprehensive intraoperative multiplane TEE examination was performed based on American Society of Echocardiography/Society of Cardiovascular Anesthesiologists guidelines (9). Transducer positioning was selected to provide optimum imaging of the interatrial septum, which is best visualized in multiplane TEE. Interatrial communications were assessed by TEE on size, position in the interatrial septum, proximity to surrounding structures, adequacy of septal rim, and Q angle (angle between the atrial septal axis and TEE transducer axis). The SA rim was the distance from the anterior border of the defect to the outer aortic wall and the IA rim was the distance from the inferior border of the defect to the mid-tricuspid valve annulus. The posterior superior rim was the distance between the superior borders of the defect to the midpoint of the inlet orifice diameter of the superior vena cava. The posterior inferior rim was the distance from the inferior border of the defect to the midpoint of the inlet orifice diameter of the inferior vena cava (see Fig. 2).
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Figure 2. The relationship of the four rims in atrial septal defect (ASD). SVC = superior vena cava, IVC = inferior vena cava, SP = posterior superior, IP = posterior inferior, SA = anterior superior, IA = anterior inferior, Ao = aorta, TV = tricuspid valve.
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TEE was also used to guide the measurement of the stretched diameter of ASD, which is the diameter of the ASD after the balloon sizing to ensure no residual color flow through the balloon (Amplatzer sizing balloon). The ASO was released only when TEE showed no or only trivial residual color flow through the connecting stent; otherwise, repositioning of the stent would be required. The final assessment of the position of the device was performed by TEE after its release.
Implantation was performed only if the atrial septal rims measured >5 mm by TEE except the SA rim.
Device
The ASO uses the concept of closing the ASD by stenting the defect with its conjoint waist. The Amplatzer device (AGA Medical Corp., Golden Valley, MN) is woven from specially heat-treated nickel-titanium wires (7,10) and can be compressed into a tiny tube for delivery. When the disk is released at the end of the tube, its spring will open and return to its original shape. As the device expands outward, it clamps the septal defect. The central waist stretches the hole tight to prevent leakage (as shown in Fig. 3).
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Results
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The median stretched diameters of the ASDs were 16 mm (range 8–25) in isolated secundum-type ASD and 18 mm (range 6–28) in ASD with attenuated SA rim. The median sizes of Amplatzer devices were 19.5 mm (range 8–28) in isolated secundum-type ASD and 18 mm (range 9–32) in ASD with attenuated SA rim, a variant of secundum-type ASD.
All devices were successfully implanted in 124 patients with ASD. Fifty-seven patients (46%) had secundum-type ASD; 67 patients (54%) had ASD with attenuated SA rim.
During ASO placement, TEE was successful in depicting all four corners and corresponding edges of each Amplatzer disk. The IA rim was clearly visualized in all 57 patients who had secundum-type ASD, but only in 61 of 67 patients (91%) with attenuated SA rim (Fig. 4a–c). In the latter group, the IA rim was difficult to clearly visualize after the device was deployed in 6 patients (9%). In these patients, the TEE showed that the IA corner of the left disk was likely deviated to the right atrium (Fig. 5b). However, there was no nonturbulent color flow Doppler signal from the left atrium to the right atrium crossing the edge of the device. By contrast, supplemental TTE performed at the same time demonstrated that the IA corner of the disk was not only well visualized, but also properly placed (Fig. 5c). Of the false images produced by TEE in these 6 patients, two had large Q angles (one was 110°, the other was 120°) (Fig. 5a) because of severe right axis deviation of the heart. The other four had thin and pliable IA rim tissue, which became distorted by the disk of the Amplatzer.
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Figure 4. a, Angle Q from mid-esophageal (ME) four-chamber view at 0° defined as the angle between the atrial septal axis (A-axis) and transducer axis (T-axis). The Q is <90° in this patient. b, ME aortic valve short axis view at 30° of TEE demonstrating the Amplatzer occluder was well seated on the posterior superior and anterior superior (SA) rims. c, In the same patient as (a), ME four-chamber view at 0° of TEE showing the anterior inferior (IA) rim well conjoined with the anterior corner of disk at both atrial sides. T = transducer, RA = right atrium, LA = left atrium, MV = mitral valve, Ao = aorta.
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Figure 5. a, Angle Q from mid-esophageal, four-chamber view at 0° was >90° in this patient. b, In the same patient, mid-esophageal, four-chamber view at 0° of TEE revealing the anterior inferior portion of the left disk was likely deviated to the right atrium (arrow).c, In the same patient, apical four-chamber view of transthoracic echocardiography. The anterior inferior corner of the disk (arrow) is not only well visualized, but also properly placed. T = transducer, LA = left atrium, RA = right atrium, A-axis = atrial septal axis, T-axis = transducer axis, MV = mitral valve, R = right disk, L = left disk.
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In another 35 of 67 patients with attenuated SA rim, the SA rim was absent but the TEE showed that the aortic wall appeared to support the anterior surface of this device without distortion. The right and left atrial corners of the disk against the wall of the aorta make a triangle, which may allow trivial residual shunt at the corners. Success of the device closure was evaluated by TTE and physical examination in follow-up for at least 3 mo.
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Discussion
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Our results indicate that TEE can provide continuous visualization of the defect and its margins to ensure that the disk is well seated during device deployment in all secundum-type ASDs and also in most ASDs with attenuated anterior rim, except in a small number of patients with unusual morphology of IA rim tissue and/or severe right heart axis deviation with large Q angle. Supplemental TTE in these particular patients was required to confirm the IA rim’s margin along with disk to ensure proper disk placement before removal of the connecting wire.
ASD with attenuated SA rim is a morphological variation of secundum-type ASD often occurring in anterior-located ASD or large ASD (ASD stretched diameter >50% of entire atrial septal length). In contrast to the interventional closure of secundum-type ASD, this is more difficult to accomplish and requires a relatively skilled cardiologist. It increases the risks of the disk impinging on the surrounding cardiac tissue or prolapsing of the disk. With deficient SA rim, IA rim becomes the only TEE landmark in the entire anterior margin of the defect. To prevent these risks, one first needs to clearly visualize the IA rim’s margin along with the corner of the extruded disk on the right and left atrial sides before the occluder is released.
TEE probe in the esophagus normally aims at the posterior aspect of the left atrium. The probe is aligned with the sagittal axis of the patient’s body instead of the interatrial septum of the heart. Normally, the interatrial septal axis from posterior to anterior is visualized with an angle of 30°–50° to the probe (11). Two of our patients with severe right axis deviation had a Q angle >90°. In these cases, TEE showed a false image that the IA corner of the left disk was likely deviating into the right atrium. This particular false image probably resulted from a large Q angle (>90°). In contrast, the TTE probe can be manipulated in the thoracic area to align with the interatrial septal axis. In other words, the transthoracic apical four-chamber view is better than the TEE in delineating the IA rim’s margin along with the Amplatzer disk when the Q angle is large (>90°). However, the transthoracic approach has limitations. It interferes with the fluoroscopy and procedure of device placement. It may subject hazardous radiation exposure to the operator’s hand. Some authors are convinced that good TEE views and easy-to-handle devices justify the transcatheter closure of ASD without the routine use of fluoroscopy (12).
After ASO placement, in ASD with deficient SA rim, the disk can distort an IA rim, which has unusual morphology of aneurysm-like or pliable tissue. Moreover, a routine procedure to fix the devices and/or ensure the mechanical stability is to perform an extensive "MN wiggle" technique (5). This means pulling the IA rim downward with tension exerted by the delivery wire into the right atrial side. The wiggle can distort the "rim-disk alignment," especially in case of an aneurysm-like or pliable IA rim. As a result, TEE diagnosis of proper disk placement became more difficult and created the false images in the four patients who needed supplemental TTE for final confirmation before the occluder was released. In addition, nonturbulent color flow Doppler signal from the edge of the device can confirm the presence of the prolapse of the disk into right atrium.
In summary, TEE was useful for confirming successful deployment of ASO in all the secundum-type ASDs and the majority of ASDs with attenuated SA rim. However, supplemental TTE was required in only a small number of patients who had particular anatomic variation of IA rim for which TEE visualization failed to reliably diagnose adequate placement of the occluder.
The use of TEE for the placement of interventional closure of ASDs and intraoperative management of these patients requires collaboration of anesthesiologists and cardiologists. Anesthesiologists have an increasingly important role of TEE monitoring whereas providing general anesthesia during ASO placement, especially in children.
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References
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Accepted for publication February 4, 2003.
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Abstract
Introduction
