Author + information
- Received July 30, 2010
- Revision received October 6, 2010
- Accepted October 8, 2010
- Published online February 1, 2011.
- Rodrigo Bagur, MD⁎,
- Josep Rodés-Cabau, MD⁎,⁎ (, )
- Daniel Doyle, MD†,
- Robert De Larochellière, MD⁎,
- Jacques Villeneuve, MD‡,
- Jerôme Lemieux, MD‡,
- Sébastien Bergeron, MD⁎,
- Mélanie Côté, MSc⁎,
- Olivier F. Bertrand, MD, PhD⁎,
- Philippe Pibarot, DVM, PhD⁎ and
- Éric Dumont, MD†
- ↵⁎Reprint requests and correspondence:
Dr. Josep Rodés-Cabau, Quebec Heart and Lung Institute—Laval University, 2725 Chemin Sainte-Foy, G1V 4G5 Quebec City, Quebec, Canada
Objectives The aim of this study was to: 1) determine the usefulness of transesophageal echocardiography (TEE) as the primary technique to guide transapical (TA) transcatheter aortic valve implantation (TAVI); and 2) to compare TEE with angiography as the primary imaging modality for TA-TAVI guidance.
Background TEE has been routinely used as an adjunct to angiography during TA-TAVI procedures, but very few data exist on the use of TEE as the primary imaging technique guiding TA-TAVI.
Methods One hundred consecutive high-risk patients (mean age 79 ± 9 years, mean logistic EuroSCORE: 25.8 ± 17.6%) who underwent TA-TAVI in our center were included. The Edwards valve was used in all cases, and all procedures were performed in an operating room without hybrid facilities. The TA-TAVI was primarily guided by angiography in the first 25 patients (A-TAVI group) and by TEE in the last 75 patients (TEE-TAVI group). Procedural, 30-day, and follow-up results were evaluated.
Results No differences were observed between groups at baseline except for a higher (p = 0.001) prevalence of moderate or severe mitral regurgitation in the TEE-TAVI group. The procedure was successful in 97.3% and 100% of the patients in the TEE-TAVI and A-TAVI groups, respectively (p = 1.0), and a lower contrast volume was used in the TEE-TAVI group (12 [5 to 20] ml vs. 40 [20 to 50] ml, p < 0.0001). There were no differences between groups in the occurrence of valve malposition needing a second valve (TEE-TAVI: 5.3%; A-TAVI: 4%; p = 1.0) or valve embolization (TEE-TAVI: 1.3%; A-TAVI: 4%; p = 0.44). The results regarding post-procedural valve hemodynamic status and aortic regurgitation were similar between groups. The survival rates at 30-day and 1-year follow-up were 87% and 75% in the TEE-group and 88% and 84% in the A-TAVI group, respectively (log-rank = 0.49).
Conclusions TEE-TAVI was associated with similar acute and midterm results as A-TAVI and significantly reduced contrast media use during the procedures. These results suggest the feasibility and safety of performing TA-TAVI procedures in an operating room without hybrid facilities, but larger studies are needed to confirm these findings.
Transapical transcatheter aortic valve implantation (TA-TAVI) has emerged as an alternative treatment for those high-risk patients with severe symptomatic aortic stenosis (AS) in which the presence of small and/or diseased iliofemoral arteries precludes the use of a transcatheter transfemoral approach (1–7). Angiography has been the primary imaging technique for guiding TAVI, and several angiographic injections are often required to obtain the best view of the native aortic valve and to position the transcatheter valve (8). However, difficulties in obtaining an optimal view of the native valve and the absence of a reference for the ventricular end of the valve prosthesis might be a limitation for the angiographic guidance of valve positioning and deployment. Also, several centers have performed TA-TAVI procedures in an operating room with a fluoroscopic C-arm (7,9–12), which in turn increases the difficulties in obtaining optimal angiographic images. Also, the risk of contrast nephropathy is potentially very high in patients undergoing TAVI, who are usually very old and exhibit a high prevalence of chronic kidney disease (CKD) (1–6,13).
Transesophageal echocardiography (TEE) has been used as a complementary imaging tool during TAVI procedures (14,15). The TEE images depict the aortic and ventricular ends of the transcatheter valve and provide a ventricular reference (anterior leaflet of the mitral valve) that might facilitate valve positioning. Also, the use of TEE rather than angiography during valve prosthesis positioning would reduce the use of contrast media, and this might lead to a decrease in the occurrence of acute kidney injury (AKI) and the need for hemodialysis after the procedure. However, few data exist on the use of TEE as a primary imaging modality to guide TAVI procedures (16,17). The aims of this study were to: 1) determine the usefulness of TEE as the primary technique for guiding TA-TAVI; and 2) compare TEE with angiography as primary imaging techniques for TA-TAVI guidance.
A total of 100 consecutive patients diagnosed with symptomatic severe AS who underwent TA-TAVI in our center between May 2007 and June 2010 under the compassionate clinical use program approved by the Canadian Department of Health and Welfare (Ottawa, Canada) were included in the study. TAVI was approved for patients with symptomatic severe AS considered either nonoperable or very high-risk surgical candidates, and all patients provided signed informed consent for the procedures. TA-TAVI was performed in the operating room by a team of cardiac surgeons, interventional cardiologists, and anesthesiologists with techniques extensively described in previous reports (3). The 23- or 26-mm Edwards SAPIEN or SAPIEN-XT transcatheter heart valves (Edwards Lifesciences, Inc., Irvine, California) were used in all cases. All clinical, echocardiographic, procedural, and post-procedural data were prospectively collected. Procedural success was defined as the implantation of a functioning valve within the aortic annulus, without intraprocedural mortality. All major procedural and post-procedural (30-day) complications were recorded, and all patients underwent a transthoracic Doppler echocardiography at hospital discharge.
Primary imaging technique: angiography
The first 25 patients of this series underwent TA-TAVI with angiography as the primary imaging technique (A-TAVI group). The procedures were performed in an operating room with a fluoroscopic C-arm. At least 2 orthogonal angiographies were performed at the beginning of the procedure. The view in which the 3 aortic sinuses and aortic valve leaflets were shown on approximately the same plane was used for valve positioning and deployment. All angiographies were performed with a pump injection of 10 to 20 cc of mixed solute (1:1) of nonionic contrast media (iodixanol) and saline. After balloon valvuloplasty, the valve prosthesis was advanced, and several angiographies were performed during valve prosthesis positioning to further determine the position of the crimped valve and its relationship on a perpendicular plane with the aortic cusps. The optimal positioning of the valve prosthesis before deployment was established when approximately one-half of the stent containing the valve prosthesis was above/below the aortic annulus as determined by angiography (Fig. 1). Valve deployment was performed under rapid pacing to minimize the risk of valve embolization. A final aortography after valve deployment was performed to confirm the correct position of the prosthesis and to determine the presence and degree of aortic regurgitation (AR). TEE was also used in all the procedures as a complementary imaging tool, but all decisions regarding the final positioning and deployment of the valve prosthesis were based primarily on the angiographic images.
Primary imaging technique: TEE
The last 75 consecutive patients of this series underwent TA-TAVI guided by TEE as the primary imaging technique (TEE-TAVI group) and with fluoroscopy/angiography as a complementary imaging tool. All procedures were performed in an operating room with a C-arm fluoroscopy system similar to the one used in the A-TAVI group. A pigtail catheter was positioned in the aortic root just at the level of the aortic annulus as a landmark, but no angiographic images were obtained at the beginning of the procedure. After balloon valvuloplasty, the valve prosthesis was advanced toward the native aortic valve, and special care was taken to appropriately identify the aortic and ventricular ends of the stent containing the valve by TEE as well as the hinge point of the anterior mitral leaflet as the principal anatomic marker for positioning the ventricular end of the stent (Fig. 2, Online Videos 1 and 2). The long-axis (approximately 120° to 130°) TEE view was used to visualize the prosthetic valve. Achieving a perpendicular position of the valve prosthesis with respect to the aortic annulus as well as an optimal coaxiality with respect to the long axis of the ascending aorta was important to obtain an optimal view of the valve prosthesis, and this was accomplished by manipulating (pulling/pushing) the guidewire through which the valve prosthesis was advanced (Fig. 3). Once an optimal TEE view of the valve prosthesis was obtained, the optimal positioning of the valve was achieved by aligning the ventricular end of the valve prosthesis with the hinge point of the anterior leaflet of the mitral valve (Fig. 2). The final adjustment of valve positioning and valve deployment was performed under rapid pacing (Online Videos 3 and 4). After valve deployment, TEE imaging evaluated the correct position of the prosthesis as well as the presence, degree, and type (central, paravalvular) of AR. Fluoroscopy was also used in all procedures as a complementary imaging tool. One to 2 angiographic injections (10 to 20 cc of iodixanol-saline, 1:1) were used in 57 of the 75 patients either during valve positioning or after valve implantation, but all decisions with regard to both the final positioning and deployment of the valve prosthesis and the need for further intervention (post-balloon dilation, implantation of a second valve prosthesis) after valve implantation were primarily based on TEE images. In 18 patients no angiography was performed (TEE-fluoroscopy guidance alone) due to very severe CKD (n = 8), severe peripheral vascular disease precluding the femoral access (n = 5), presence of complex plaques in the aortic arch (n = 2), and medical team decision with no specific reason detailed (n = 3).
Clinical follow-up was carried out by clinical visits or through telephone contact. Patients were followed at 1 month, 6 months, and 1 year after the procedure and annually thereafter. Death and reintervention at any time during the follow-up period were recorded.
Qualitative variables were expressed as percentages, and quantitative variables were expressed as mean ± SD or median (25th to 75th interquartile range) depending on variable normality distribution as determined by Shapiro-Wilk tests. Group comparisons were analyzed with Student t test or the Wilcoxon rank-sum test for continuous variables and chi-square test or Fisher exact test for categorical variables. Analysis of variance for repeated measures was performed to test for equal means between baseline and follow-up. For aortic valve area and mean gradient, a 2-way analysis of variance for repeated measures with interaction was used to compare the changes in aortic valve area and mean gradient between baseline and follow-up and between TEE-TAVI and TA-TAVI groups. Survival rates at 1-year follow-up were presented as Kaplan-Meier curves, and the log-rank test was used for comparison between groups. Differences were considered statistically significant when a p value was <0.05. The data were analyzed with SAS statistical software version 9.1.3 (SAS Institute Inc., Cary, North Carolina).
Baseline clinical and echocardiographic characteristics of the study population are shown in Table 1, and procedural and 30-day outcomes for the entire population are shown in Table 2. The procedure was successful in 98% of the patients, and there were no procedural deaths. A total of 13 patients died within the 30 days after the procedure due to multi-organ failure (n = 5), cardiogenic shock (n = 2), sudden unexplained death (n = 2), sepsis (n = 2), cardiac rupture (n = 1), and respiratory distress syndrome (n = 1).
Primary imaging modality for guiding TA-TAVI: angiography versus TEE
Baseline clinical and echocardiographic characteristics of the A-TAVI and TEE-TAVI groups are shown in Table 3. There were no significant differences between groups at baseline, except for a higher prevalence of moderate or severe mitral regurgitation in the TEE-TAVI group. Procedural and 30-day outcomes grouped according to the primary imaging modality for guiding the TAVI procedure are shown in Table 4. There were no differences between groups with regard to procedural success (A-TAVI: 100%, TEE-TAVI: 97.3%, p = 1.0), but procedural time was shorter (p = 0.005) and contrast amount was lower (p < 0.0001) in the TEE-TAVI group. Valve embolization occurred in 1 patient in each group (A-TAVI: 4%; TEE-TAVI: 1.3%, p = 0.44). One patient in the A-TAVI group complicated with severe transvalvular AR due to the low positioning of the valve prosthesis that was treated with the implantation of a second valve (valve-in-valve procedure). However, the 2 valves embolized into the left ventricle 48 h after the procedure. The patient underwent emergent open heart surgery but died within the next 24 h due to severe multiorgan failure. Valve prosthesis embolization immediately after valve deployment occurred in 1 patient in the TEE-TAVI group, due to the presence of severe septal myocardial hypertrophy protruding into the left ventricular outflow tract. The prosthesis embolized in the ascending aorta and was finally deployed in the distal part of the aortic arch. The patient underwent successful surgical aortic valve replacement 2 months after the procedure. Valve malposition needing a second valve due to transvalvular or paravalvular severe AR occurred in 1 patient (4%) in the A-TAVI group (low positioning) and in 4 patients (5.3%) in the TEE-TAVI group (low and high positioning in 1 and 3 cases, respectively). Two patients in the TEE-TAVI group (2.7%) complicated with coronary obstruction due to the displacement of a bulky calcified native aortic leaflet toward the coronary ostia. One patient was treated with emergent fem-fem extracorporeal circulation and coronary bypass graft due to left main coronary ostia occlusion, and the other patient underwent transradial coronary angioplasty at 24-h after TA-TAVI. No cases of valve embolization, valve malposition, or coronary obstruction occurred in the group of 18 patients who underwent TA-TAVI procedure fully guided by TEE and fluoroscopy, with no angiography. The procedural time in this group was 67.4 ± 14.7 min, which was similar to that observed in the rest of the TEE-TAVI group (p = 0.31) and shorter (p = 0.002) compared with the A-TAVI group. A total of 6 patients (6%) needed hemodynamic support with cardiopulmonary bypass—1 patient in the A-TAVI group (4%) and 5 patients in the TEE-TAVI group (6.7%), p = 1.0. The reasons for needing hemodynamic support during the TA-TAVI procedure were severe, maintained hypotension or hemodynamic collapse secondary to ventricular apical tear/bleeding (n = 1), life-threatening arrhythmias (n = 2), left main occlusion (n = 1), and severe valvular/paravalvular regurgitation (n = 2). One patient in the TEE-TAVI group needed surgical aortic valve replacement 3 days after the procedure due to severe transvalvular AR leading to cardiac failure. The 30-day mortality rate was similar between the A-TAVI (12%) and TEE-TAVI (13.3%) groups, p = 1.0.
Valve hemodynamic status
There was a significant reduction in mean aortic gradient (from 40 ± 16 mm Hg to 11 ± 6 mm Hg, p < 0.0001) and increase in aortic valve area (from 0.62 ± 0.16 cm2 to 1.56 ± 0.29 cm2, p < 0.0001) after the procedure, with no differences between TEE-TAVI and A-TAVI groups (p = 0.36 for gradient, p = 0.16 for valve area) (Fig. 4). Most patients (65%) had some degree of residual AR at hospital discharge, mostly trivial (53%) or mild (13%). There were no patients with moderate or severe AR, and there were no differences (p = 0.69) in the occurrence and degree of AR between A-TAVI and TEE-TAVI groups (Fig. 5).
Clinical follow-up was available in all patients at a median of 6 months (25th to 75th interquartile range 1 to 18 months) after TA-TAVI. A total of 8 patients died during the follow-up period, leading to a cumulative death rate of 21%. The reasons of death during the follow-up period were the following: sudden death (n = 2); lung cancer (n = 2); larynx cancer (n = 1); sepsis secondary to diabetic foot (n = 1); pneumonia (n = 1); and end stage renal disease (n = 1). There were no cases of valve structural failure or reintervention.
The Kaplan-Meier survival curves at 1-year follow-up for the A-TAVI and TEE-TAVI groups are shown in Fig. 6. Survival rate at 1-year follow-up was 84% in the A-TAVI group and 75% in the TEE-TAVI group (log-rank = 0.49).
In patients diagnosed with severe symptomatic AS deemed inoperable or at very high surgical risk, TA-TAVI guided by TEE as the primary imaging modality was associated with acceptable acute and midterm results, similar to those obtained with angiography as the primary imaging technique. TEE-TAVI was also associated with a significant decrease in procedural contrast volume without increasing the rates of valve embolization or malpositioning. Also, the present study suggests that performing TEE-TAVI procedures in a regular operating room with a standard fluoroscopic C-arm and without hybrid facilities is feasible and safe.
Angiography and TEE as primary imaging modality
Aortic angiography has been used as the primary imaging technique for guiding TA-TAVI procedures (9–12). This involves the realization of at least 2 orthogonal angiographic projections to obtain a view where the 3 aortic leaflets are visualized on approximately the same plane. Obtaining such a view is 1 critical aspect of the TA-TAVI procedure guided by angiography and in many cases might require several angiographies. Also, the final positioning of the transcatheter valve with approximately one-half of the stent containing the valve above/below the aortic annulus might be challenging in some cases and is associated with a somewhat subjective decision of the physician performing the procedure, who would have to trace an imaginary line identifying the aortic annulus and determine that approximately one-half of the valve prosthesis would have to be above/below that line. Therefore, it is not surprising that the final positioning of the valve prosthesis might in some cases require several angiographic injections and could be frequently associated with some discrepancies among the different operators participating in the procedure. All these potential difficulties associated with the angiographic guidance of TA-TAVI might be exacerbated by the use of nonoptimal angiographic view systems such as a fluoroscopic C-arm. The recent development of the C-THV software (Paieon, Park Afek, Israel) (18) and real-time 3-dimensional reconstruction systems of the aortic root and ascending aorta (19,20) should represent an important step in facilitating and improving the valve positioning process during TA-TAVI. However, this implies the use of high-quality imaging equipment in operating rooms with hybrid facilities, not yet available in most centers performing TA-TAVI procedures worldwide. Also, the financial implications of acquiring such hybrid operating rooms might slow its implementation in the near future. In fact, many centers have already decided to perform TA-TAVI in the catheterization laboratory to optimize angiographic imaging during the procedures. However, many catheterization laboratories do not comply with the strict sterility regulations of an operating room, and this could increase the risk of surgical infections. Also, performing a mini-thoracotomy procedure such as TA-TAVI in the catheterization laboratory might be associated with more logistic and technical difficulties and can also be a challenging scenario in case of procedural complications requiring emergent conversion to open heart surgery, which occurs in approximately 4% (0% to 7.5%) of TA-TAVI cases (1–7,9–12).
TEE has been increasingly used in recent years for guiding cardiac surgical and catheter-based interventions (15). Also, TEE has been used as a complementary imaging technique from the early days of TAVI (14,15). TEE enables the accurate measurement of the aortic annulus, the early detection of the most important complications associated with the procedure, and the evaluation of valve hemodynamic status and the presence and type of AR (transvalvular vs. paravalvular) immediately after valve implantation. However, very little data exist on the role of TEE during key points of the TAVI procedure, such as valve positioning and deployment (14–17). As shown in the present study, TEE can provide very accurate images of the transcatheter valve before deployment (Fig. 2). Also, and unlike angiographic guiding, TEE allows the use of other anatomic markers such as the mitral valve, which might make TEE a more reliable and reproducible technique for valve positioning. The anterior mitral leaflet is separated from the septum by the subaortic vestibule, which has a fibrous continuity with a triangle formed between the noncoronary and left coronary aortic leaflet, making the aortic and mitral valves directly adjacent to each other and forming the roof of the left ventricle (21). We previously reported that the hinge point of the anterior mitral valve leaflet could be used to guide the positioning of a transcatheter aortic valve (16). The present study, which includes the largest consecutive series of TA-TAVI procedures primarily guided by TEE, supports the usefulness of this anatomical marker for guiding valve positioning and deployment. The procedure was successful in 97.3% of the cases, with rates of valve embolization, valve malpositioning needing a second valve, and conversion to open heart surgery of 1.3%, 5.3%, and 2.7%, respectively—which are similar to the rates reported in previous TA-TAVI series (4–7,9–12). Also, the rate of major complications (16%) and mortality (13.3%) at 30 days were similar to previous TA-TAVI studies. Ferrari et al. (17) recently reported the results of 30 patients who underwent TA-TAVI guided by TEE, with no contrast injection in up to 22 patients. Interestingly, the echocardiographic landmark used for valve positioning was, unlike ours, an imaginary line linking the hinge points of the aortic valve leaflets, with approximately one-third of the valve prosthesis above and two-thirds below this line. Consistent with our results, procedural success was achieved in 96.7% of the cases, with an incidence of valve embolization of 3.3% and no cases of valve malpositioning. However, future studies will have to determine the cost-effectiveness of TEE-TAVI (vs. A-TAVI) as well as the potential risks associated with radiation exposure for the TEE operators.
Avoiding contrast media: a close eye on kidney function
Patients undergoing TAVI nowadays are commonly very old and have a high prevalence of CKD (1–6,13). It is well-known that the use of contrast media can complicate with the occurrence of AKI (contrast-induced nephropathy), especially in those patients with previous CKD, and this complication has been associated with a significant increase in post-procedural mortality (22). Also, we have previously shown that the occurrence of AKI after TAVI was associated with a 4-fold increase of in-hospital mortality after the procedure (13). Previous TA-TAVI studies have reported rates of up to 7% to 13.4% of new hemodialysis after the procedure (6,7,23). The present study showed that the use of TEE as the primary imaging technique guiding TA-TAVI procedures was associated with a dramatic reduction in contrast media use, with a median contrast volume as low as 12 ml and no contrast use in up to 18 patients. Interestingly, only 1.3% of the patients required hemodialysis after the procedure. The absence of differences with the A-TAVI group in the present study might be due to both the relatively low amount of contrast (median 40 ml) used in the A-TAVI group and the tendency toward a higher degree of renal dysfunction in the TEE-TAVI group at baseline. Consistent with our results, Ferrari et al. (17) reported no cases of new hemodialysis among 30 patients who underwent TA-TAVI guided by TEE. Future studies will have to evaluate the potential benefits for post-procedural kidney function of reducing the contrast volume by guiding the TA-TAVI procedures primarily with TEE.
Our results apply exclusively to TAVI procedures performed by TA approach and cannot be extrapolated to transfemoral procedures. In our experience valve identification and positioning by TEE might be more challenging in those procedures performed by transfemoral approach (difficulties in obtaining a perfect coaxiality of the valve prosthesis in the center of the aortic annulus, catheter-nosecone artifacts, lower profile of the stent valve prosthesis), and future studies should specifically evaluate the feasibility and usefulness of TEE as the primary imaging modality in such cases. Also, the results of this study apply only to TAVI procedures primarily guided by TEE with fluoroscopy/angiography as a complementary imaging tool. Although the results obtained in the 18 patients who underwent the procedure with no angiography were promising, future studies including a larger number of patients are needed to confirm the safety and efficacy of TAVI fully guided by TEE with no angiography. The relatively low number of patients included, especially in the A-TAVI group, might have played a role in the absence of differences between groups. Also, the comparison between A-TAVI and TEE-TAVI groups has the limitation that the A-TAVI group represented our initial TA-TAVI experience, and the results in this group might have been negatively influenced by the effects of the learning curve. Although the results obtained in the TEE-TAVI group are also similar to those reported in previous TA-TAVI series with angiography as a primary imaging technique, they will have to be confirmed by studies including a larger number of patients and similar levels of experience in both A-TAVI and TEE-TAVI groups.
The use of TEE as the primary imaging technique for guiding TA-TAVI was associated with clinical and hemodynamic results similar to those of angiographic TA-TAVI guidance. Also, TEE-TAVI was associated with a significant reduction in the use of contrast media during the procedures, and this might have major clinical implications with respect to the occurrence of post-procedural contrast nephropathy. Finally, although an operating room with hybrid facilities is the optimal scenario to perform TA-TAVI procedures, our results suggest the feasibility and safety of performing TA-TAVI procedures in a regular operating room without hybrid facilities. The confirmation of these findings in future studies might have important logistic and financial implications in the near future when a very rapid expansion of TAVI procedures worldwide is expected and many new centers, most of them with no hybrid operating rooms, will want to start a TA-TAVI program.
The authors thank Ms. Jacinthe Aubé, RN, and Ms. Nathalie Boudreau, for their outstanding work in the follow-up of patients, and Mr. Mark Dehdashtian, from Edwards Lifesciences, Inc., for his technical support.
For supplementary videos and their legends, please see the online version of this article.
The study was supported in part by a grant (MOP-57745) of the Canadian Institutes of Health Research. Dr. Bagur receives research grants from the Quebec Heart & Lung Institute Research Center. Drs. Rodés-Cabau, Dumont, and Lemieux are consultants for Edwards Lifesciences, Inc. Dr. Pibarot has received honoraria for presentations and research grants from Edwards Lifesciences, Inc. All other authors report that they have no relationships to disclose.
- Abbreviations and Acronyms
- acute kidney injury
- aortic regurgitation
- aortic stenosis
- angiography guiding transapical transcatheter aortic valve implantation
- chronic kidney disease
- transapical transcatheter aortic valve implantation
- transesophageal echocardiography
- transesophageal echocardiography guiding transapical transcatheter aortic valve implantation
- Received July 30, 2010.
- Revision received October 6, 2010.
- Accepted October 8, 2010.
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