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On-line intracardiac echocardiography alone for Amplatzer Septal Occluder selection and device deployment in adult patients with atrial septal defect
International Journal of Cardiology 95 (2004) 61 – 68 www.elsevier.com/locate/ijcard
On-line intracardiac echocardiography alone for Amplatzer Septal Occluder selection and device deployment in adult patients with atrial septal defect M. Zanchetta Cardiovascular Department, Cittadella General Hospital, Cittadella, Padova, Italy Received 16 October 2002; received in revised form 16 April 2003; accepted 21 April 2003
Abstract Background: During the last few years, several different devices have been proposed for atrial septal defect (ASD) percutaneous closure. For the Amplatzer Septal Occluder (ASO) device, accurate balloon sizing is considered of paramount importance because the prosthesis waist has to be exactly adjusted to the defect diameter (F1 mm). In this study, we aimed to demonstrate the possibility of marked misinterpreting of the actual defect size using the balloon technique in patients with secundum ASD and to evaluate the accuracy of intracardiac echocardiography (ICE) measurements as a new method for selecting the size of ASO device. Methods: Between February 1999 and December 2000, 166 consecutive adult patients underwent percutaneous transvenous secundum ASD occlusion using the ASO device. In 124 patients (control group), ASD were closed by conventional methods. In 13 patients (pilot group), balloon pulling technique was used in size selection, whereas ICE was used on-line to monitor device placement and off-line to assess its possibilities for accurate quantitative measurements and qualitative evaluation. In 31 patients (study group), ICE was used as the sole imaging tool both for guiding device selection and monitoring the procedure. All patients underwent complete transthoracic echocardiographic study before discharge and during follow-up visits at 3 and 12 months. Results: Successful device implantation was accomplished in 163 of the 166 patients (98.2%). Shortterm follow-up results were available in all eligible patients at least 3 months. Complete occlusion was demonstrated in 91.4% and 92.2% of patients in the control and pilot groups, respectively, increasing to 97.3% in the study group (p<0.01 vs. both control and pilot groups). There were no significant differences in mean ASO diameters in the control and pilot groups (20F7.7 and 22F5.4 mm, respectively), whereas the mean size of the devices used in the study group was significantly larger (27.4F6.2 mm, p<0.01 vs. both control and pilot groups). In the pilot group, the underestimation effect of the balloon strategy was evident, with a mean 12.3% larger diameter required on ICE measurements. Moreover, a misalignment between the ASO and the atrial septum was seen on ICE in 9 of 13 patients of the pilot group, whereas good apposition of the ASO on the septum secundum was seen in all patients of the study group. Conclusion: ICE is a safe and effective method for selecting ASO size and continuous monitoring of the procedure. In contrast to the previously reported implantation procedure (device-to-defect ratio 1:1), a device 10 – 20% larger than invasively measured stretched defect diameter should be chosen and implanted on the basis of the ICE data. D 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Intracardiac echocardiography; Atrial septal defect; Amplatzer Septal Occluder
1. Introduction Balloon sizing technique and two-dimensional transesophageal echocardiography (TEE) examinations were originally described, as a precise determination of secundum atrial septal defect (ASD) diameter to aid size device selection [1 – 4] and as a helpful imaging technique for real-time monitoring transcatheter closure procedures [5,6]. Both methods became widely accepted and entered routine E-mail address: [email protected] (M. Zanchetta). 0167-5273/$ - see front matter D 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2003.04.022
clinical practice without being validated by a controlled clinical trial. Clinical experience and observational data have identified the limits of these methods, but they continue to be the ‘‘gold standard’’ for all transcatheter occlusion procedures. Over the past few years, at least five different devices with different design and implantation methods have undergone clinical trials including the various generations of the Sideris’ buttoned occluder, the Babic’s atrial septal defect occluding system, the Das’ Angel Wings device, the modified Clamshell (STARFlex) device and the Amplatzer Septal Occluder (ASO). These devices essentially offer two differ-
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M. Zanchetta / International Journal of Cardiology 95 (2004) 61–68 Table 1 Clinical and procedural data Control group Pilot group Study group P (124 patients) (13 patients) (31 patients)
Fig. 1. Characterization of the study population.
ent approaches to ASD closure. The first four use the general concept of defect ‘‘patching’’, mimicking surgery. The ASO ‘‘plugs’’ the hole by stenting the defect with its waist. The purpose of this study was twofold. Firstly, to evaluate the accuracy of intracardiac echocardiography (ICE) measurements, as an alternative to the standard methods to help select and monitor deployment of the ASO device. Secondly, to adopt a mixed doctrine, consisting of the application of the ASO device in a ‘‘patching approach’’ to not only close the defect, but also cover the fossa ovalis.
2. Materials and methods 2.1. Study population Between February 1999 and December 2000, percutaneous transvenous ASD occlusion was attempted in 166 consecutive patients by inserting an ASO device (Fig. 1).
M/F Age (years) BSA Shunt (Qp/Qs)
33/91 40.5 F 20.6 1.70 F 0.17 1.85 F 0.7
5/8 42.7 F 14.2 1.69 F 0.15 2.35 F 0.54
7/24 42.5 F 19.3 1.71 F 0.10 1.55 F 0.55
PA (mm Hg) PT (min) FT (min)
28.7 F 12.0 75.5 F 28.7 16.1 F 9.8
17.6 F 6.4 63.3 F 13.5 15.6 F 2.9
21.4 F 11.7 75.2 F 28.7 14.4 F 7.9
NS*,a,# NS*,a,# NS*,a,# NS* 0.05a 0.001# NS*,a,# NS*,a,# NS*,a,#
BSA: body surface area; FT = fluoroscopy time; M/F = male/female; PA = mean pulmonary artery pressure; PT = procedural time. * Control vs. pilot group. a Control vs. study group. # Pilot group vs. study group.
The first 124 patients represented the control group, in which the ASD was closed by using ASO sized by conventional methods, i.e., balloon catheter sizing and two-dimensional TEE. The last 44 patients were assigned to the working group of ICE. During the first 3 months of the investigation, ASO size selection was guided by balloon sizing, whereas ICE was used on-line, as an alternative to TEE, as the main imaging tool for monitoring the procedure and off-line to assess its possibilities for accurate qualitative evaluation and quantitative measurements (pilot group = 13 patients). In this group, prior to device release, two-dimensional transthoracic
Fig. 2. (A) Intracardiac echocardiography imaging session at the aortic plane. Image is in the short axis of the left atrium (LA) and right atrium (RA). The tissue surrounding the atrial septal defect can be well identified and measured as follows: superior – posterior rim (SP) and superior – anterior rim (SA). The crista terminalis (CT) is easily identifiable as well as the guide wire (GW) and the Ultra ICE catheter (arrow). (B) Intracardiac echocardiography imaging session at the four-chamber plane. The inferior – anterior (IA) and inferior – posterior (IP) rims can be well appreciated, whereas mitral (MV) and tricuspid (TV) valve apparatus is in the anterior far field.
M. Zanchetta / International Journal of Cardiology 95 (2004) 61–68 Table 2 Results with different ASO selection size strategies
were informed of the novelty of the approach used and consented to participate in this study.
Control group Pilot group Study group P (124 patients) (13 patients) (31 patients) TEE Stretched ASOp (mm) ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi d ¼ ðA4=pÞ Septal apposition Septal distortion
15.7 F 6.4 19.5 F 7.5 20 F 7.7 NA NA NA
16.4 F 6.1 21.4 F 5.3 22 F 5.4 24.4 F 5.61 4/13 9/13
NA NA 27.4 F 6.2 27.4 F 6.2 31/31 0/31
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NS* NS* NS*,0.01# NS# 0.01# 0.01#
ASO: Amplatzer Septal Occluder; TEE: transesophageal echocardiography. * Control vs. pilot group. # Pilot group vs. study group.
colour Doppler echocardiographic study was performed to assess residual shunting. After the first 3 months, on the basis of the interim results, ICE was used as the only imaging tool both for guiding device selection and monitoring the procedure (study group = 31 patients). In contrast to most studies that have dealt with selected subsets of ASDs, the study group had no exclusion criteria because the patients did not undergo TEE examination before the procedure. All patients provided informed and written consent: moreover, patients assigned to the working group of ICE
2.2. ASO implantation procedure All patients received aspirin and antibiotic prophylaxis immediately before the procedure. A bolus of 70 U/kg heparin was given after sheath insertion, with a repeat bolus of 35 U/kg given as needed to maintain activated clotting time >250 s. In the control group, balloon sizing (Meditech Occlusion Balloon Catheter, Boston Scientific, Watertown, MA) and TEE monitoring (Acuson, Mountain View, CA) were performed as described elsewhere [7– 12]. The implantation procedures of ASO device (AGA Medical, Golden Valley, MN) were performed under general anaesthesia or deep intravenous sedation. In the ICE working group, deployment of the device was done only under local anaesthesia: in the pilot group, a multiplane transesophageal probe was available in the catheterization laboratory for use at any time if needed, whereas in the study group, there were no restrictions on the operator to prevent him from switching to balloon sizing and/or TEE at any time during the procedure.
Fig. 3. Off-line intracardiac ultrasound assessment of the released Amplatzer Septal Occluder (ASO). The ASO device was undersized leaving uncovered a substantial margins of the septum primum (SP). Note the thinness of this structure compared with the septum secundum (SS).
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2.3. Intracardiac echocardiographic equipment, measurements and derived diameters The ultrasound intracardiac echo catheter (Ultra ICEk, model 9900) is a disposable, 9F-9 MHz, 110 cm in length, monoplane probe (EP Technologies, Boston Scientific, San Jose, CA, USA). It is supplied fully assembled, with a proximal connector compatible with a motor drive unit and an imaging console of the Clear View Ultra (version 4.22 or higher). It is introduced through a 10 F, 55j precurved polyethylene long sheath venous system, in order to enhance the directionality of the catheter tip. Axial and lateral resolution is 0.27 and 0.26 mm, respectively, whereas the radial depth of penetration is approximately 5 cm. Validation of quantitative measurements and pathological correlations with intracardiac imaging have been reported [13 –20]. Two-way tip articulation of the Ultra ICE catheter on fluoroscopy was used in order to obtain two orthogonal tomographic imaging planes of the atrial septum at the fossa ovalis. The axial view was achieved on the aortic valve plane with the Ultra ICE catheter perpendicular to the transverse axis of the body (Fig. 2A); the longitudinal view was obtained on the four-chamber plane, bisecting both left
and right atria, with the Ultra ICE catheter astride the ASD (Fig. 2B). The following measurements were made at the level of the fossa ovalis using only end-diastolic frames: fossa ovalis major axes on the aortic (a) and four-chamber (b) planes; fossa ovalis area (FOA), calculated by assuming its shape as an ideal ellipse, using the formula: FOA = pab/ 4. This measurement was thought to be a reasonable and practical reflection of the area of the fossa ovalis, including both the ASD and the thin surrounding remnant tissue of the septum primum. Subsequently, the diameter of the equivalent circle, of the same area as the fossa ovalis, pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi was calculated as follows: d ¼ ðFOA 4=pÞ , or d ¼ pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ða bÞ, where d is the diameter of the equivalent circle of the elliptical FOA. Intraobserver variability with repeated measurements was < 3%. 2.4. Intracardiac echocardiography criteria for optimal ASO choice and placement Optimal device size selection and placement was judged using both quantitative and qualitative ICE criteria. Quantitative criteria were governed by the principle of optimising device size in order to cover the area of the fossa ovalis. The waist of the device was appropriately selected to correspond
Fig. 4. Off-line intracardiac ultrasound assessment of the released Amplatzer Septal Occluder (ASO). The ASO devise was undersized and misaligned on the atrial septum. SS, septum secundum; SP, septum primum.
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to the equivalent circle diameter of the fossa ovalis ( = d value), estimated using ICE measurements. Qualitative criteria included: (1) complete waist apposition to the septum secundum with symmetrical expansion of the two retention disks, (2) optimal ASO alignment on the atrial septum and (3) no evidence of damage to the surrounding structures, including the orifices of the venae cavae, the ostium of the coronary sinus, the outlet of the right pulmonary veins and the mitral and tricuspid apparatus.
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2.6. Statistical analysis Data are expressed as mean F S.D. for continuous, normally distributed values. Comparison of continuous variables among groups was performed using the ANOVA test. Subgroup comparison of categorical variables was performed using the chi-square analysis. Statistical significance was set at p value < 0.05.
2.5. Follow-up
3. Results
As a precaution, low-dose antiplatelet therapy and endocarditic prophylaxis were recommended for 6 months. All patients underwent complete transthoracic echocardiographic study before discharge and during follow-up visits at 3 and 12 months. The location and size of residual shunting on colour Doppler echocardiography were classified according to previously published protocols [21]. Chest radiogram was also obtained before discharge and repeated at 12 months.
The clinical characteristics and interventional data of the control, pilot and study groups are summarized in Table 1. A total of 167 ASO devices were implanted in 166 patients. Successful device implantation was accomplished in 163 (98.2%) of the 166 patients. In the control group, there were two failures due to device embolization into the left ventricular inflow tract and the left pulmonary artery, with emergency and elective conversion to open ASD repair and
Fig. 5. Intracardiac ultrasound shows optimal device placement with the Amplatzer Septal Occluder (ASO) astride the atrial septum. RA, right atrium; RV, right ventricle; TV, tricuspid valve.
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ASO removal, respectively, with no major clinical events. In the pilot group, one device was retrieved before its release because it prolapsed into the body of the left atrium due to its fixation on a thin, floppy atrial septal aneurysm and the patient underwent successful surgical closure. In the study group, all defect closures were uneventful, and the ICE provided sufficient information to make correct decisions. In fact, conversion to balloon sizing/TEE-guided procedure was never necessary. Moreover, both in the pilot and study groups, ICE four-chamber plane provided adequate imaging during the various stages of the deployment, facilitating the device placement. Overall procedural success, defined as no or trivial residual shunt on echocardiography performed within 24 h of device implantation, was obtained in 89.7% of the 163 patients in whom the ASO was successfully implanted: 88% in the control group, 87.8% in the pilot group and 93.4% in the study group. Mean duration of follow-up was 16 F 7 months. Short-term follow-up data were available in 41 eligible patients of the ICE working group after at least three months. At follow-up, complete occlusion was achieved in 91.4% and 92.2% of patients in the control and pilot groups, respectively, whereas the complete occlusion rate was higher in the study group, reaching up to 97.3% ( p < 0.01 vs. both control and pilot groups). The effects of the two different approaches of device selection and deployment are shown in Table 2. There were no significant differences in mean ASO diameters in the control and pilot groups, whereas the mean size of the devices used in the study group was significantly larger ( p < 0.01 vs. both control and pilot groups). In the pilot group, balloon sizing technique resulted in a 21.4 F 5.3 mm mean ASO diameter, whereas off-line ICE measurements suggested a significantly higher diameter (24.4 F 5.6 mm, p < 0.05). However, the final ASO implanted device was based on the balloon sizing diameters and its mean value was 22 F 5.4 mm (waist diameter). In this group, the underestimation effect of the balloon strategy was evident, with a mean 12.3% larger diameter required on ICE measurements (Fig. 3). Moreover, a misalignment between the ASO and the atrial septum was seen on ICE in 9 of 13 patients in the pilot group (Fig. 4). By changing the strategy, mean final ASO implanted device in the study group was 27.4 F 6.2 mm ( p < 0.01 vs. both control and pilot groups) and the ICE evaluation showed a good apposition of the ASO on the septum secundum in all patients (Fig. 5). In the pilot group, the underestimation effect of the balloon strategy, with or without misalignment between the ASO and the atrial septum, depended mostly on the size of the flap valve that kept the device away from the muscular rim of the fossa ovalis. There were no complications related to the use of the ICE catheter in both the pilot and the study groups. It was noteworthy that 9 of 13 patients of the pilot group, who underwent transcatheter closure without general anaesthesia or deep sedation, reported thoracic discomfort during the balloon manoeuvre, whereas the remaining four patients complained of real, constrictive chest pain.
4. Discussion The main aim of the present study was to assess the feasibility and safety of ASO implantation under ICE guidance alone. The novelty of this approach to ASO implantation is twofold: on the one hand, ICE guidance replaces both balloon sizing guidance and TEE monitoring, and on the other hand, fossa ovalis coverage is used as an alternative to the hole stenting doctrine. This approach was derived on the base of observations made during off-line ICE evaluation in the pilot group. Despite high procedural success and the excellent rate of complete occlusion at follow-up in this group, off-line ICE measurements revealed the need for larger devices to ensure sufficient straddling of the waist on the muscular septum secundum, in order to align properly on the atrial septum. A 2 –4 mm larger device than the measured balloon defect diameter has also been suggested by Berger et al. [22] and Fischer et al. [11] who, although did not validate their findings, suggested this overestimation in order to compensate for the easily distended pliable rim tissue and to ensure stable device positioning after implantation. In contrast to the regular and reported implantation procedure [8,10 – 12] (device– defect ratio 1:1), our off-line ICE data in the pilot group supported the hypothesis that the ASO device must be overestimated by approximately 10 – 20% in diameter to close ASD >20 mm. In our opinion, this mismatch between balloon sizing and implanted ASO device corresponds to inadequate fossa ovalis rather than hole coverage and is due to insufficient information on rim tissue provided by a blind technique such as balloon sizing. On the basis of knowledge gained during the course of the pilot study, quantitative ICE measurements alone were achieved in the study group which never resulted in the reported ‘‘mushrooming malformation’’, avoiding any significant misalignment between the ASO and the secundum atrial septum and increasing the complete occlusion rate to 97.3% during the short-term follow-up. The current study indicates that ICE guidance is a safe and effective procedure for selecting ASO size and continuous monitoring of its deployment in patients with ASD and demonstrates the feasibility of the mixed approach in covering the fossa ovalis. In our opinion, a correctly selected ASO should not be based on the size of the defect but on the size of the fossa ovalis and should provide gentle stenting of the muscular rims of the fossa ovalis which is not often the case with the balloon sizing technique. The main advantages of ICE guidance include: (1) high imaging quality and superior soft-tissue contrast due to short distance of interrogated tissue from the transducer and uniform omni-directional back-scatter of the red cell (i.e., no acoustical impediments), (2) good patient compliance for a relatively prolonged period of time, since ICE obviates the need for TEE monitoring and therefore for general anaesthesia with or without endotracheal intubation, (3) userfriendly requiring just one operator, (i.e., no anaesthetist or echocardiographer), exposed to ionizing radiadion sickness,
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(4) no interference from ICE probe during fluoroscopy, no danger of missing the sterile field and (5) limited fluoroscopic exposure time once the techniques is learnt. In conclusion, our findings are a departure from the previous well-accepted hole stenting doctrine and suggest an alternative approach to percutaneous closure of moderate – large ASD. 4.1. Study limitations Although this study has documented the application of significantly larger ASO when ICE was used to guide ASO device selection, the small number of patients, the lack of randomisation and the short-term follow-up do not enable definitive conclusions to be drawn. Moreover, the ICE criteria used in this study for optimal ASO selection and placement still remains to be validated as clinically useful. Refinements and possibly guidelines for ICE evaluation of percutaneous deployment of the ASO are likely to develop with further studies. The single rotating ultrasound element catheter used in this study did not provide Doppler hemodynamic data, as the multielement electronic ultrasound phased-array catheter [23,24] does. However, in our opinion, this approach that gives fossa ovalis coverage without any need for balloon sizing would not necessarily require simultaneous intracardiac Doppler examination, because there should be no residual shunting through the fossa ovalis. In fact, a perfect fit of the device to the septum secundum can be expected, and, therefore, residual leaks should not occur. Finally, ICE assessment of FOA does not obviate the need for geometric assumptions. Alternatively planimetric methods such as those derived form three-dimensional TEE [25 –27] or magnetic resonance imaging [28] ‘‘en face’’ reconstruction may be applied.
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
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On-line intracardiac echocardiography alone for Amplatzer Septal Occluder selection and device deployment in adult patients with atrial septal defect M. Zanchetta Cardiovascular Department, Cittadella General Hospital, Cittadella, Padova, Italy Received 16 October 2002; received in revised form 16 April 2003; accepted 21 April 2003
Abstract Background: During the last few years, several different devices have been proposed for atrial septal defect (ASD) percutaneous closure. For the Amplatzer Septal Occluder (ASO) device, accurate balloon sizing is considered of paramount importance because the prosthesis waist has to be exactly adjusted to the defect diameter (F1 mm). In this study, we aimed to demonstrate the possibility of marked misinterpreting of the actual defect size using the balloon technique in patients with secundum ASD and to evaluate the accuracy of intracardiac echocardiography (ICE) measurements as a new method for selecting the size of ASO device. Methods: Between February 1999 and December 2000, 166 consecutive adult patients underwent percutaneous transvenous secundum ASD occlusion using the ASO device. In 124 patients (control group), ASD were closed by conventional methods. In 13 patients (pilot group), balloon pulling technique was used in size selection, whereas ICE was used on-line to monitor device placement and off-line to assess its possibilities for accurate quantitative measurements and qualitative evaluation. In 31 patients (study group), ICE was used as the sole imaging tool both for guiding device selection and monitoring the procedure. All patients underwent complete transthoracic echocardiographic study before discharge and during follow-up visits at 3 and 12 months. Results: Successful device implantation was accomplished in 163 of the 166 patients (98.2%). Shortterm follow-up results were available in all eligible patients at least 3 months. Complete occlusion was demonstrated in 91.4% and 92.2% of patients in the control and pilot groups, respectively, increasing to 97.3% in the study group (p<0.01 vs. both control and pilot groups). There were no significant differences in mean ASO diameters in the control and pilot groups (20F7.7 and 22F5.4 mm, respectively), whereas the mean size of the devices used in the study group was significantly larger (27.4F6.2 mm, p<0.01 vs. both control and pilot groups). In the pilot group, the underestimation effect of the balloon strategy was evident, with a mean 12.3% larger diameter required on ICE measurements. Moreover, a misalignment between the ASO and the atrial septum was seen on ICE in 9 of 13 patients of the pilot group, whereas good apposition of the ASO on the septum secundum was seen in all patients of the study group. Conclusion: ICE is a safe and effective method for selecting ASO size and continuous monitoring of the procedure. In contrast to the previously reported implantation procedure (device-to-defect ratio 1:1), a device 10 – 20% larger than invasively measured stretched defect diameter should be chosen and implanted on the basis of the ICE data. D 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Intracardiac echocardiography; Atrial septal defect; Amplatzer Septal Occluder
1. Introduction Balloon sizing technique and two-dimensional transesophageal echocardiography (TEE) examinations were originally described, as a precise determination of secundum atrial septal defect (ASD) diameter to aid size device selection [1 – 4] and as a helpful imaging technique for real-time monitoring transcatheter closure procedures [5,6]. Both methods became widely accepted and entered routine E-mail address: [email protected] (M. Zanchetta). 0167-5273/$ - see front matter D 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2003.04.022
clinical practice without being validated by a controlled clinical trial. Clinical experience and observational data have identified the limits of these methods, but they continue to be the ‘‘gold standard’’ for all transcatheter occlusion procedures. Over the past few years, at least five different devices with different design and implantation methods have undergone clinical trials including the various generations of the Sideris’ buttoned occluder, the Babic’s atrial septal defect occluding system, the Das’ Angel Wings device, the modified Clamshell (STARFlex) device and the Amplatzer Septal Occluder (ASO). These devices essentially offer two differ-
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M. Zanchetta / International Journal of Cardiology 95 (2004) 61–68 Table 1 Clinical and procedural data Control group Pilot group Study group P (124 patients) (13 patients) (31 patients)
Fig. 1. Characterization of the study population.
ent approaches to ASD closure. The first four use the general concept of defect ‘‘patching’’, mimicking surgery. The ASO ‘‘plugs’’ the hole by stenting the defect with its waist. The purpose of this study was twofold. Firstly, to evaluate the accuracy of intracardiac echocardiography (ICE) measurements, as an alternative to the standard methods to help select and monitor deployment of the ASO device. Secondly, to adopt a mixed doctrine, consisting of the application of the ASO device in a ‘‘patching approach’’ to not only close the defect, but also cover the fossa ovalis.
2. Materials and methods 2.1. Study population Between February 1999 and December 2000, percutaneous transvenous ASD occlusion was attempted in 166 consecutive patients by inserting an ASO device (Fig. 1).
M/F Age (years) BSA Shunt (Qp/Qs)
33/91 40.5 F 20.6 1.70 F 0.17 1.85 F 0.7
5/8 42.7 F 14.2 1.69 F 0.15 2.35 F 0.54
7/24 42.5 F 19.3 1.71 F 0.10 1.55 F 0.55
PA (mm Hg) PT (min) FT (min)
28.7 F 12.0 75.5 F 28.7 16.1 F 9.8
17.6 F 6.4 63.3 F 13.5 15.6 F 2.9
21.4 F 11.7 75.2 F 28.7 14.4 F 7.9
NS*,a,# NS*,a,# NS*,a,# NS* 0.05a 0.001# NS*,a,# NS*,a,# NS*,a,#
BSA: body surface area; FT = fluoroscopy time; M/F = male/female; PA = mean pulmonary artery pressure; PT = procedural time. * Control vs. pilot group. a Control vs. study group. # Pilot group vs. study group.
The first 124 patients represented the control group, in which the ASD was closed by using ASO sized by conventional methods, i.e., balloon catheter sizing and two-dimensional TEE. The last 44 patients were assigned to the working group of ICE. During the first 3 months of the investigation, ASO size selection was guided by balloon sizing, whereas ICE was used on-line, as an alternative to TEE, as the main imaging tool for monitoring the procedure and off-line to assess its possibilities for accurate qualitative evaluation and quantitative measurements (pilot group = 13 patients). In this group, prior to device release, two-dimensional transthoracic
Fig. 2. (A) Intracardiac echocardiography imaging session at the aortic plane. Image is in the short axis of the left atrium (LA) and right atrium (RA). The tissue surrounding the atrial septal defect can be well identified and measured as follows: superior – posterior rim (SP) and superior – anterior rim (SA). The crista terminalis (CT) is easily identifiable as well as the guide wire (GW) and the Ultra ICE catheter (arrow). (B) Intracardiac echocardiography imaging session at the four-chamber plane. The inferior – anterior (IA) and inferior – posterior (IP) rims can be well appreciated, whereas mitral (MV) and tricuspid (TV) valve apparatus is in the anterior far field.
M. Zanchetta / International Journal of Cardiology 95 (2004) 61–68 Table 2 Results with different ASO selection size strategies
were informed of the novelty of the approach used and consented to participate in this study.
Control group Pilot group Study group P (124 patients) (13 patients) (31 patients) TEE Stretched ASOp (mm) ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi d ¼ ðA4=pÞ Septal apposition Septal distortion
15.7 F 6.4 19.5 F 7.5 20 F 7.7 NA NA NA
16.4 F 6.1 21.4 F 5.3 22 F 5.4 24.4 F 5.61 4/13 9/13
NA NA 27.4 F 6.2 27.4 F 6.2 31/31 0/31
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NS* NS* NS*,0.01# NS# 0.01# 0.01#
ASO: Amplatzer Septal Occluder; TEE: transesophageal echocardiography. * Control vs. pilot group. # Pilot group vs. study group.
colour Doppler echocardiographic study was performed to assess residual shunting. After the first 3 months, on the basis of the interim results, ICE was used as the only imaging tool both for guiding device selection and monitoring the procedure (study group = 31 patients). In contrast to most studies that have dealt with selected subsets of ASDs, the study group had no exclusion criteria because the patients did not undergo TEE examination before the procedure. All patients provided informed and written consent: moreover, patients assigned to the working group of ICE
2.2. ASO implantation procedure All patients received aspirin and antibiotic prophylaxis immediately before the procedure. A bolus of 70 U/kg heparin was given after sheath insertion, with a repeat bolus of 35 U/kg given as needed to maintain activated clotting time >250 s. In the control group, balloon sizing (Meditech Occlusion Balloon Catheter, Boston Scientific, Watertown, MA) and TEE monitoring (Acuson, Mountain View, CA) were performed as described elsewhere [7– 12]. The implantation procedures of ASO device (AGA Medical, Golden Valley, MN) were performed under general anaesthesia or deep intravenous sedation. In the ICE working group, deployment of the device was done only under local anaesthesia: in the pilot group, a multiplane transesophageal probe was available in the catheterization laboratory for use at any time if needed, whereas in the study group, there were no restrictions on the operator to prevent him from switching to balloon sizing and/or TEE at any time during the procedure.
Fig. 3. Off-line intracardiac ultrasound assessment of the released Amplatzer Septal Occluder (ASO). The ASO device was undersized leaving uncovered a substantial margins of the septum primum (SP). Note the thinness of this structure compared with the septum secundum (SS).
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2.3. Intracardiac echocardiographic equipment, measurements and derived diameters The ultrasound intracardiac echo catheter (Ultra ICEk, model 9900) is a disposable, 9F-9 MHz, 110 cm in length, monoplane probe (EP Technologies, Boston Scientific, San Jose, CA, USA). It is supplied fully assembled, with a proximal connector compatible with a motor drive unit and an imaging console of the Clear View Ultra (version 4.22 or higher). It is introduced through a 10 F, 55j precurved polyethylene long sheath venous system, in order to enhance the directionality of the catheter tip. Axial and lateral resolution is 0.27 and 0.26 mm, respectively, whereas the radial depth of penetration is approximately 5 cm. Validation of quantitative measurements and pathological correlations with intracardiac imaging have been reported [13 –20]. Two-way tip articulation of the Ultra ICE catheter on fluoroscopy was used in order to obtain two orthogonal tomographic imaging planes of the atrial septum at the fossa ovalis. The axial view was achieved on the aortic valve plane with the Ultra ICE catheter perpendicular to the transverse axis of the body (Fig. 2A); the longitudinal view was obtained on the four-chamber plane, bisecting both left
and right atria, with the Ultra ICE catheter astride the ASD (Fig. 2B). The following measurements were made at the level of the fossa ovalis using only end-diastolic frames: fossa ovalis major axes on the aortic (a) and four-chamber (b) planes; fossa ovalis area (FOA), calculated by assuming its shape as an ideal ellipse, using the formula: FOA = pab/ 4. This measurement was thought to be a reasonable and practical reflection of the area of the fossa ovalis, including both the ASD and the thin surrounding remnant tissue of the septum primum. Subsequently, the diameter of the equivalent circle, of the same area as the fossa ovalis, pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi was calculated as follows: d ¼ ðFOA 4=pÞ , or d ¼ pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ða bÞ, where d is the diameter of the equivalent circle of the elliptical FOA. Intraobserver variability with repeated measurements was < 3%. 2.4. Intracardiac echocardiography criteria for optimal ASO choice and placement Optimal device size selection and placement was judged using both quantitative and qualitative ICE criteria. Quantitative criteria were governed by the principle of optimising device size in order to cover the area of the fossa ovalis. The waist of the device was appropriately selected to correspond
Fig. 4. Off-line intracardiac ultrasound assessment of the released Amplatzer Septal Occluder (ASO). The ASO devise was undersized and misaligned on the atrial septum. SS, septum secundum; SP, septum primum.
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to the equivalent circle diameter of the fossa ovalis ( = d value), estimated using ICE measurements. Qualitative criteria included: (1) complete waist apposition to the septum secundum with symmetrical expansion of the two retention disks, (2) optimal ASO alignment on the atrial septum and (3) no evidence of damage to the surrounding structures, including the orifices of the venae cavae, the ostium of the coronary sinus, the outlet of the right pulmonary veins and the mitral and tricuspid apparatus.
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2.6. Statistical analysis Data are expressed as mean F S.D. for continuous, normally distributed values. Comparison of continuous variables among groups was performed using the ANOVA test. Subgroup comparison of categorical variables was performed using the chi-square analysis. Statistical significance was set at p value < 0.05.
2.5. Follow-up
3. Results
As a precaution, low-dose antiplatelet therapy and endocarditic prophylaxis were recommended for 6 months. All patients underwent complete transthoracic echocardiographic study before discharge and during follow-up visits at 3 and 12 months. The location and size of residual shunting on colour Doppler echocardiography were classified according to previously published protocols [21]. Chest radiogram was also obtained before discharge and repeated at 12 months.
The clinical characteristics and interventional data of the control, pilot and study groups are summarized in Table 1. A total of 167 ASO devices were implanted in 166 patients. Successful device implantation was accomplished in 163 (98.2%) of the 166 patients. In the control group, there were two failures due to device embolization into the left ventricular inflow tract and the left pulmonary artery, with emergency and elective conversion to open ASD repair and
Fig. 5. Intracardiac ultrasound shows optimal device placement with the Amplatzer Septal Occluder (ASO) astride the atrial septum. RA, right atrium; RV, right ventricle; TV, tricuspid valve.
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ASO removal, respectively, with no major clinical events. In the pilot group, one device was retrieved before its release because it prolapsed into the body of the left atrium due to its fixation on a thin, floppy atrial septal aneurysm and the patient underwent successful surgical closure. In the study group, all defect closures were uneventful, and the ICE provided sufficient information to make correct decisions. In fact, conversion to balloon sizing/TEE-guided procedure was never necessary. Moreover, both in the pilot and study groups, ICE four-chamber plane provided adequate imaging during the various stages of the deployment, facilitating the device placement. Overall procedural success, defined as no or trivial residual shunt on echocardiography performed within 24 h of device implantation, was obtained in 89.7% of the 163 patients in whom the ASO was successfully implanted: 88% in the control group, 87.8% in the pilot group and 93.4% in the study group. Mean duration of follow-up was 16 F 7 months. Short-term follow-up data were available in 41 eligible patients of the ICE working group after at least three months. At follow-up, complete occlusion was achieved in 91.4% and 92.2% of patients in the control and pilot groups, respectively, whereas the complete occlusion rate was higher in the study group, reaching up to 97.3% ( p < 0.01 vs. both control and pilot groups). The effects of the two different approaches of device selection and deployment are shown in Table 2. There were no significant differences in mean ASO diameters in the control and pilot groups, whereas the mean size of the devices used in the study group was significantly larger ( p < 0.01 vs. both control and pilot groups). In the pilot group, balloon sizing technique resulted in a 21.4 F 5.3 mm mean ASO diameter, whereas off-line ICE measurements suggested a significantly higher diameter (24.4 F 5.6 mm, p < 0.05). However, the final ASO implanted device was based on the balloon sizing diameters and its mean value was 22 F 5.4 mm (waist diameter). In this group, the underestimation effect of the balloon strategy was evident, with a mean 12.3% larger diameter required on ICE measurements (Fig. 3). Moreover, a misalignment between the ASO and the atrial septum was seen on ICE in 9 of 13 patients in the pilot group (Fig. 4). By changing the strategy, mean final ASO implanted device in the study group was 27.4 F 6.2 mm ( p < 0.01 vs. both control and pilot groups) and the ICE evaluation showed a good apposition of the ASO on the septum secundum in all patients (Fig. 5). In the pilot group, the underestimation effect of the balloon strategy, with or without misalignment between the ASO and the atrial septum, depended mostly on the size of the flap valve that kept the device away from the muscular rim of the fossa ovalis. There were no complications related to the use of the ICE catheter in both the pilot and the study groups. It was noteworthy that 9 of 13 patients of the pilot group, who underwent transcatheter closure without general anaesthesia or deep sedation, reported thoracic discomfort during the balloon manoeuvre, whereas the remaining four patients complained of real, constrictive chest pain.
4. Discussion The main aim of the present study was to assess the feasibility and safety of ASO implantation under ICE guidance alone. The novelty of this approach to ASO implantation is twofold: on the one hand, ICE guidance replaces both balloon sizing guidance and TEE monitoring, and on the other hand, fossa ovalis coverage is used as an alternative to the hole stenting doctrine. This approach was derived on the base of observations made during off-line ICE evaluation in the pilot group. Despite high procedural success and the excellent rate of complete occlusion at follow-up in this group, off-line ICE measurements revealed the need for larger devices to ensure sufficient straddling of the waist on the muscular septum secundum, in order to align properly on the atrial septum. A 2 –4 mm larger device than the measured balloon defect diameter has also been suggested by Berger et al. [22] and Fischer et al. [11] who, although did not validate their findings, suggested this overestimation in order to compensate for the easily distended pliable rim tissue and to ensure stable device positioning after implantation. In contrast to the regular and reported implantation procedure [8,10 – 12] (device– defect ratio 1:1), our off-line ICE data in the pilot group supported the hypothesis that the ASO device must be overestimated by approximately 10 – 20% in diameter to close ASD >20 mm. In our opinion, this mismatch between balloon sizing and implanted ASO device corresponds to inadequate fossa ovalis rather than hole coverage and is due to insufficient information on rim tissue provided by a blind technique such as balloon sizing. On the basis of knowledge gained during the course of the pilot study, quantitative ICE measurements alone were achieved in the study group which never resulted in the reported ‘‘mushrooming malformation’’, avoiding any significant misalignment between the ASO and the secundum atrial septum and increasing the complete occlusion rate to 97.3% during the short-term follow-up. The current study indicates that ICE guidance is a safe and effective procedure for selecting ASO size and continuous monitoring of its deployment in patients with ASD and demonstrates the feasibility of the mixed approach in covering the fossa ovalis. In our opinion, a correctly selected ASO should not be based on the size of the defect but on the size of the fossa ovalis and should provide gentle stenting of the muscular rims of the fossa ovalis which is not often the case with the balloon sizing technique. The main advantages of ICE guidance include: (1) high imaging quality and superior soft-tissue contrast due to short distance of interrogated tissue from the transducer and uniform omni-directional back-scatter of the red cell (i.e., no acoustical impediments), (2) good patient compliance for a relatively prolonged period of time, since ICE obviates the need for TEE monitoring and therefore for general anaesthesia with or without endotracheal intubation, (3) userfriendly requiring just one operator, (i.e., no anaesthetist or echocardiographer), exposed to ionizing radiadion sickness,
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(4) no interference from ICE probe during fluoroscopy, no danger of missing the sterile field and (5) limited fluoroscopic exposure time once the techniques is learnt. In conclusion, our findings are a departure from the previous well-accepted hole stenting doctrine and suggest an alternative approach to percutaneous closure of moderate – large ASD. 4.1. Study limitations Although this study has documented the application of significantly larger ASO when ICE was used to guide ASO device selection, the small number of patients, the lack of randomisation and the short-term follow-up do not enable definitive conclusions to be drawn. Moreover, the ICE criteria used in this study for optimal ASO selection and placement still remains to be validated as clinically useful. Refinements and possibly guidelines for ICE evaluation of percutaneous deployment of the ASO are likely to develop with further studies. The single rotating ultrasound element catheter used in this study did not provide Doppler hemodynamic data, as the multielement electronic ultrasound phased-array catheter [23,24] does. However, in our opinion, this approach that gives fossa ovalis coverage without any need for balloon sizing would not necessarily require simultaneous intracardiac Doppler examination, because there should be no residual shunting through the fossa ovalis. In fact, a perfect fit of the device to the septum secundum can be expected, and, therefore, residual leaks should not occur. Finally, ICE assessment of FOA does not obviate the need for geometric assumptions. Alternatively planimetric methods such as those derived form three-dimensional TEE [25 –27] or magnetic resonance imaging [28] ‘‘en face’’ reconstruction may be applied.
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
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