Safety and Efficacy of Simultaneous Biplane Mode of 3-Dimensional Transesophageal Echocardiography-Guided Antegrade Multiple-Inflation Balloon Aortic Valvuloplasty in Patients With Severe Aortic Stenosis

Abstract

Background: Balloon aortic valvuloplasty (BAV) is resurging as a bridge treatment in patients with severe aortic stenosis (AS) with a dissemination of transcatheter aortic valve implantation. However, the significantly high periprocedural mortality and complication rates still limit the indications of BAV. Further efforts are needed to improve the safety and efficacy of BAV.

Methods and Results: We retrospectively investigated the safety and efficacy of simultaneous biplane mode of 3-dimensional transesophageal echocardiography (biplane-TEE) guided antegrade transseptal multiple-inflation BAV, with gradual upsizing of the balloon, by enrolling 20 consecutive AS patients who underwent BAV. The median age was 83 years, and there were 6 male patients (30.0%). The clinical frailty scale was 4, and the Society of Thoracic Surgeon score was 14.5%. The balloon was inflated at a median of 18 times, which improved the mean aortic valve pressure gradient from 43.0 to 15.2 mmHg (P<0.001). We safely performed BAV in all patients, without periprocedural death or symptomatic stroke, although asymptomatic stroke was detected in 8 patients (42.1%) on diffusion-weighted magnetic resonance imaging. Kaplan-Meier estimates showed that the survival rate was 84.0% and cardiovascular death-free survival was 88.9% at 1-year.

Conclusions: Biplane-TEE guided antegrade multiple-inflation BAV might have the potential to improve periprocedural survival without increasing complications, compared with conventional retrograde BAV in patients with severe AS.

Severe aortic stenosis (AS) is the most common cause of left ventricular outflow impairment and results in a symptomatic hemodynamic collapse and high cardiovascular mortality.^1,2 For decades, surgical aortic valve replacement (SAVR) has been the treatment of choice for severe AS, because it prolongs life expectancy.^1,2 Transcatheter aortic valve implantation (TAVI) has been recently recognized as a viable therapeutic option in patients who have an unacceptably high surgical risk.^1–6 With a significant increase in the number of TAVI procedures performed worldwide, and with the recent expansion in the indications for TAVI to include patients with intermediate surgical risk as candidates, there has been a resurgence of interest in balloon aortic valvuloplasty (BAV) among physicians and surgeons as a bridge therapy for TAVI or SAVR, even with a class IIb recommendation and level of evidence C as per the international guidelines.^7–10

The most expected favorable therapeutic effect of BAV as a bridge to TAVI or SAVR is achieving acute hemodynamic stability because it is very difficult to medically manage hemodynamic collapse in patients with severe AS.¹¹ However, the significant incidence of periprocedural complications such as acute-phase cardiovascular death possibly from the acute valve recoil phenomenon, procedure-related stroke, and acute aortic regurgitation (AR), and no recent improvement in the outcomes of BAV despite advancements in interventional devices over the past 2 decades, still limit the indication of BAV as a bridge therapy.^7,8,12–14

Thus, new procedural approaches of BAV to reduce the risk of severe complications in the acute phase can contribute to the management of severe AS patients in the recent TAVI era. Hence, we hypothesized that simultaneous biplane mode of 3-dimensional (3D) transesophageal echocardiography (biplane-TEE) guided multiple-inflation BAV with gradual upsizing of the balloon would reduce risks such as the acute recoil phenomenon and acute AR, which may result in fewer periprocedural cardiovascular deaths. Moreover, the antegrade transseptal approach of BAV has the potential to decrease vascular complications such as stroke by avoiding catheter manipulation in a severely atherosclerotic calcified ascending aorta as compared with the retrograde approach.^14–18 The objective of this single-center, retrospective, observational study was to investigate the short-term efficacy and safety of biplane-TEE guided antegrade transseptal multiple-inflation BAV.

Methods

Study Population

From among 30 patients who underwent BAV between November 2014 and June 2016 at Osaka City University Hospital, we enrolled 20 consecutive patients with severe AS who underwent biplane-TEE guided antegrade transseptal multiple-inflation BAV for the management of acute heart failure, in preparation for noncardiac surgery or as a bridge therapy for TAVI (Figure 1). We retrospectively collected data from the patient records, so the requirement of written informed consent was waived. Three cases were previously reported as image-content-sharing case reports, but because this is an original research article, the case reports do not violate the duplication policy of the journal.¹⁹ The study protocol complied with the Helsinki Declaration, and was approved by the Ethical Committee of Osaka City University Hospital (Approval No. 3015). The authors had full access to the data and were responsible for its integrity. All authors read and agreed to the manuscript as written.

Figure 1.

Flowchart of patient selection for balloon aortic valvuloplasty (BAV). AS, aortic stenosis; 3D-TEE, 3-dimensional transesophageal echocardiography.

Standard Protocol of BAV

As preparation for the BAV procedure, patients underwent 3D-TEE and contrast-enhanced multislice computed tomography (MSCT) in order to assess the size of the aortic complex including aortic annular diameter, and in order to detect calcium deposition. If patients had renal dysfunction, plane MSCT was performed to evaluate the calcium deposits without contrast enhancement. BAV was performed under general anesthesia in a hybrid operating room. First, we placed a 14Fr sheath, a 5Fr sheath, and a 7Fr sheath in the right femoral vein, left femoral artery, and left femoral vein, respectively. Next, the left atrium was accessed by an 8.5Fr, 63-cm LAMP135^TM sheath (St. Jude Medical, MN, USA) from the right femoral vein, using a standard-curved Radiofrequency NRG^TM transseptal needle (Baylis Medical, Inc., Montreal, QC, Canada), under fluoroscopic and 3D-TEE guidance. We utilized both the 3D-Live mode and simultaneous biplane mode of 3D-TEE during the Brockenbrough procedure to puncture the thinnest septal portion in the fossa ovalis (Figure 2). A single-lumen 7Fr balloon-tipped catheter (Gadelius Medical K.K, Tokyo, Japan) was advanced, inside the LAMP135^TM sheath, across the mitral valve into the left ventricle, and then looped in the left ventricular apex and directed towards the outflow tract. A 0.64-mm, 250-cm long guidewire (Radifocus^®, Terumo, Tokyo, Japan) was advanced through the balloon-tipped catheter to navigate it into the descending aorta. In the descending aorta, the Radifocus^® wire was exchanged for a 0.81-mm, 260-cm extra-stiff guidewire (Cook Medical, Bloomington, IN, USA), which was anchored using a 10-mm GooseNeck^® Snare (Covidien, Plymouth, MN, USA) inserted from the left femoral artery access. After removing the balloon-tipped catheter and the LAMP135^TM sheath, an INOUE-BALLOON catheter (Toray Industries, Inc., Tokyo, Japan) was advanced over the extra-stiff wire, and positioned across the aortic valve.

Figure 2.

Representative image of the Brockenbrough procedure under fluoroscopic and 3D-TEE guidance. We accessed the LA under fluoroscopic (A) and 3D-TEE guidance utilizing both the 3D Live-mode (B, from the left atrial view) and simultaneous biplane mode (C) of 3D-TEE to puncture the thinnest part of the fossa ovalis (yellow circle). Simultaneous biplane mode of 3D-TEE demonstrated that the tip of the Radiofrequency NRG^TM transseptal needle (yellow arrows) were about to puncture the thinnest part of the fossa ovalis while keeping a safe distance from the SVC and MV. (Modified with written permission from J Typ Med Images Video 2016: Case ID 207, http://thejtmiv.com, last accessed on November 11, 2016.) 3D-TEE, 3-dimensional live transesophageal echocardiography; LA, left atrium; MV, mitral valve; RA, right atrium; SVC, superior vena cava.

During the crossing of the balloon through the mitral valve and subvalvular apparatus towards the aortic valve, a cardiologist monitored and evaluated mitral regurgitation (MR) using both 3D Live-mode TEE and biplane-TEE to prevent hemodynamic instability and significant decrease of blood pressure caused by increased MR. A temporary pacemaker lead was inserted from the left femoral vein and placed at the right ventricular apex for rapid pacing (150–180 ppm) in order to stabilize the balloon’s position across the valve. The size of the INOUE-BALLOON catheter was based on the annulus long-diameter measured on the preprocedural 3D reconstructed TEE image. Although we also performed contrast-enhanced MSCT to assess the size of aortic annulus in 15 patients without renal dysfunction, the annulus long-diameter measured by MSCT was just a reference in this study. The balloon was inflated from the 4-mm down size diameter to the target size several times for each balloon size under real-time simultaneous biplane mode of 3D-TEE monitoring to evaluate the position of the balloon, the inflation, and the presence of acute AR. We used the simultaneous biplane mode rather than the 3D Live-mode during the balloon inflation procedure because the 3D Live-mode TEE image could not appropriately detect calcification deposits. We set the procedural endpoint as the balloon inflation with sufficient diameter under biplane-TEE monitoring. In many cases, sufficient inflation of the balloon indicated close attachment without any space between the balloon’s surface and the aortic annulus, and could be achieved with the pre-procedurally determined balloon size, but severe calcification and a bulky aortic valve sometimes prevented us achieving this. Figure 3 shows a representative case of 3D-TEE guided antegrade transseptal multiple-inflation BAV.

Figure 3.

Representative case of 3D-TEE guided antegrade multiple-inflation BAV. The 18 mm (A), 19 mm, 20 mm (B), 21 mm, and 22 mm (C) INOUE BALLOONS are inflated 4, 2, 4, 4 and 4 times (in this order), respectively, under careful 3D-TEE monitoring. Long-axis (D) and short-axis (E) views of real-time 3D-TEE demonstrating that the 22-mm balloon is appropriately positioned and inflated at the site of the AV, with sufficient inflation diameter (arrows). Hemodynamic measurements before (F) and after (G) BAV show a significant improvement in the mean AV pressure gradient from 50.7 to 8.4 mmHg, the peak AV pressure gradient from 63.0 to 2.0 mmHg, and the cardiac index from 1.8 to 2.3 L/min/m². (Modified with written permission from J Typ Med Images Video 2016: Case ID 179 and 180, http://thejtmiv.com, last accessed on November 11, 2016.) Ao, aorta; AV, aortic valve; LV, left ventricle; RV, right ventricle. Other abbreviations as in Figures 1,2.

Endpoints and Statistical Analysis

We set the primary endpoint as 1-year-all-cause death, and the secondary endpoint as 1-year-cardiovascular death. During the study period, we also assessed the cumulative incidence of bridge to TAVI and the periprocedural complication rate, including symptomatic and asymptomatic cerebral or cerebellar infarction, acute AR, acute MR, annulus rupture, cardiac tamponade, and major bleeds requiring transfusion. Asymptomatic cerebral or cerebellar infarction was assessed using diffusion-weighted magnetic resonance imaging (DWI), performed within 3 days after BAV. Procedure-related acute AR or MR was defined as significant exacerbation of regurgitation grade on color Doppler images with real-time 3D and biplane-TEE monitoring.

Continuous variables were summarized using medians and interquartile range (quartiles 1–3), and categorical variables were summarized by means of counts and percentages. Hemodynamic efficacy of biplane-TEE guided antegrade transseptal multiple-inflation BAV was compared pre- and post-procedurally using the Wilcoxon signed-rank test, which is a nonparametric statistical hypothesis test used to compare 2 sets of scores from the same participants. The incidences of 1-year all-cause death, cardiovascular death, and bridge to TAVI were estimated using the Kaplan-Meier method, with a 95% confidence interval (CI) (Figure 3). All statistical analyses were performed using R software package (version 3.1.1; R Development Core Team).

Results

The patients’ characteristics are listed in Table 1. Median age of the study population was 83 years (quartile range 77–87) and 6 patients (30.0%) were male. Prevalence of hypertension (90%) and dyslipidemia (65%) were high in this study population, as compared with other atherosclerotic risks. More than half of the patients presented with New York Heart Association (NYHA) functional class III or higher. The median Canadian study of health and aging clinical frailty scale was 4 (4–4), and Society of Thoracic Surgeons (STS) surgical mortality risk score estimate was 14.5% (8.8–20.3%). Preoperative transthoracic echocardiography (TTE) showed the median aortic valve area with the Doppler method was 0.71 cm² (0.55–0.80 cm²). Table 2 shows the procedure-related information and the direct hemodynamic measurements before and after biplane-TEE guided antegrade transseptal multiple-inflation BAV. The balloon inflation maneuver was performed a median of 18 (12–26) times during the procedure per patient, under biplane-TEE monitoring. As a result, the mean aortic valve pressure gradient (mAVPG) with simultaneous catheter measurement significantly decreased from 43.0 mmHg (28.0–53.6 mmHg) to 15.2 mmHg (11.2–23.7 mmHg) (P<0.001), and aortic valve area according to the Gorlin equation significantly increased from 0.61 cm² (0.49–0.73 cm²) to 1.19 cm² (1.00–1.49 cm²) (P<0.001).

Table 1. Characteristics of Patients With Severe Aortic Stenosis Undergoing Balloon Aortic Valvuloplasty

Parameters	Missing	n=20
Age (years)	0	83 (77–87)
Male	0	6 (30.0)
Atherosclerotic risks
Hypertension	0	18 (90.0)
Dyslipidemia	0	13 (65.0)
Diabetes mellitus	0	3 (15.0)
Current smoking	0	3 (15.0)
Hemodialysis	0	1 (5.0)
Prior PCI	0	5 (25.0)
Previous MI	0	3 (15.0)
NYHA class
II	0	9 (45.0)
III	0	10 (50.0)
IV	0	1 (5.0)
Clinical frailty scale	0	4 (4–4)
STS score	0	14.5 (8.8–20.3)
Laboratory data
BNP (pg/mL)	0	117.8 (73.1–612.2)
eGFR (mL/min/1.73 m2)	0	44.1 (32.1–61.7)
eGFR <30 or hemodialysis	0	5 (25.0)
Transthoracic echocardiography
LV end-diastolic diameter (mm)	0	47 (41–50)
LV end-systolic diameter (mm)	0	29 (23–39)
LV ejection fraction (%)	0	57.5 (45.0–63.3)
Peak aortic velocity (m/s)	0	4.5 (3.9–4.8)
Mean AV pressure gradient (mmHg)	0	47.5 (31.5–55.3)
Peak AV pressure gradient (mmHg)	0	81.5 (61.3–92.0)
AV area with Doppler (cm2)	0	0.71 (0.55–0.80)

Categorical variables are shown as numbers (percentages) and continuous variables are shown as medians (25–75th percentile). AV, aortic valve; BNP, B-type natriuretic peptide; eGFR, estimated glomerular filtration rate; LV, left ventricle; MI, myocardial infarction; NYHA, New York Heart Association; PCI, percutaneous coronary intervention; STS, Society of Thoracic Surgeons.

Table 2. Procedure-Related Information and Hemodynamic Efficacy of 3D-TEE Guided Antegrade Multiple-Inflation BAV

Parameter	Missing	Procedural
Procedure-related information
Annulus diameter by TTE	0	20.0 (19.8–21.0)	–	–
Annulus long-diameter by 3D-TEE	0	23.0 (22.0–24.0)
Annulus long-diameter by MSCT	5	24.5 (24.1–25.7)
Balloon size (mm)	0	22 (23–24)
Beginning size (mm)	0	19 (18–20)	–	–
Final size (mm)	0	23 (22–25)	–	–
No. of balloon inflations	0	18 (12–26)	–	–
Operation time (min)	0	151 (120–183)	–	–
	Missing	Preprocedural	After BAV	P value
Direct hemodynamic measurements
LV end-diastolic pressure (mmHg)	0	15 (10–21)	11 (9–18)	0.477
Cardiac index (L/min/m2)	0	2.4 (2.0–2.5)	2.6 (2.2–3.2)	0.009
Mean AV pressure gradient (mmHg)	0	43.0 (28.0–53.6)	15.2 (11.2–23.7)	<0.001
AV area with Gorlin equation (cm2)	0	0.61 (0.49–0.73)	1.19 (1.00–1.49)	<0.001

Categorical variables are shown as numbers (percentages) and continuous variables are shown as medians (25–75th percentile). BAV, balloon aortic valvuloplasty; MSCT, multislice computed tomography; TEE, transesophageal echocardiography; TTE, transthoracic echocardiography. Other abbreviations as in Table 1.

Periprocedural complications are summarized in Table 3. There was no case of any significant complications such as symptomatic cerebral or cerebellar infarction, AR, MR, annulus rupture, cardiac tamponade, or major bleeding, although biplane-TEE detected injury to the mitral subvalvular apparatus, which slightly increased regurgitation without significant exacerbation of regurgitation grade in 1 case. In contrast, DWI detected asymptomatic cerebral or cerebellar infarction in 8 patients (42.1%). The median number of hotspots detected on DWI was 2 (1–3). There were 2 deaths: 1 from sepsis, and the other from uremic syndrome caused by acute renal failure, which was counted as a cardiovascular death in the present study. As shown in Figure 2, the Kaplan-Meier estimates showed that the survival rate was 100.0% (95% CI, 100.0–100.0%) at 1 month, 94.4% (84.4–100.0%) at 6 months, 84.0% (64.9–100.0%) at 1 year (Figure 4A). Cardiovascular death-free survival rates were 100.0% (100.0–100.0%) at both 1 and 6 months, and 88.9% (70.6–100%) at 12 months (Figure 4B). A total of 10 patients underwent TAVI during the study period, with an estimated cumulative incidence of 0.0% (0.0–0.0%) at 1 month, 26.7% (3.4–44.4%) at 6 months, and 61.2% (16.3%-79.6%) at 12 months (Figure 4C).

Table 3. Periprocedural Complications of 3D-TEE Guided Antegrade Multiple-Inflation BAV

Parameter	Missing	n=20
Symptomatic cerebral or cerebellar infarction	0	0 (0.0)
Asymptomatic cerebral or cerebellar infarction by DWI-MRI	1	8 (42.1)
No. of hotspots by DWI-MRI	1	2 (1–3)
Acute aortic regurgitation	0	0 (0.0)
Acute mitral regurgitation	0	0 (0.0)
Annulus rupture	0	0 (0.0)
Cardiac tamponade	0	0 (0.0)
Major bleed needing transfusion	0	0 (0.0)

Categorical variables are shown as numbers (percentages) and continuous variables are shown as medians (25–75th percentile). DWI, diffusion-weighted image; MRI, magnetic resonance imaging. Other abbreviations as in Table 2.

Figure 4.

(A–C) Kaplan-Meier estimates of each endpoint. Dotted line indicates 95% confidence interval. CV, cardiovascular; TAVI, transcatheter aortic valve implantation.

Discussion

In this study, we retrospectively summarized our experience with 20 cases of biplane-TEE guided antegrade transseptal multiple-inflation BAV with gradual upsizing of the balloon in symptomatic AS patients, focusing on its safety and efficacy. We demonstrated the following: short-term hemodynamic efficacy with an improvement in mAVPG from 43.0 mmHg to 15.2 mmHg; short-term safety by the absence of any periprocedural deaths or significant complications except for asymptomatic stroke revealed on DWI; favorable 1-year survival (84.0%), and favorable cardiovascular death-free survival (88.9%). To the best of our knowledge, this BAV procedural strategy, especially the antegrade multiple-balloon inflations with gradual upsizing of the balloon, has never been reported. Thus, our study is the first and the largest case series, demonstrating the possible advantages of biplane-TEE guided antegrade multiple-inflation BAV compared with conventional retrograde BAV. Hence, we believe our results provide physicians with unique and valuable information regarding BAV.

Efficacy of the New BAV Procedure

Direct hemodynamic measurement revealed that biplane-TEE guided antegrade multiple-inflation BAV had a sufficient therapeutic effect, with significant improvement in mAVPG from 43.0 mmHg to 15.2 mmHg (P<0.001) and in aortic valve area from 0.61 to 1.19 cm² (P<0.001). Conversely, the most noteworthy finding in our study is the relatively low mortality rate after BAV, with a 1-month all-cause mortality rate of 0% (95% CI 0.0–0.0%), a 6-month all-cause mortality rate of 5.6% (0.0–15.6%), and a 1-year all-cause mortality rate of 16.0% (0.0–35.1%) (Figure 3A). A recent multicenter study demonstrated that the 1-month or in-hospital all-cause mortality rate ranged from 5.1% to 7.4%, and the 1-year all-cause mortality ranged from 30% to 34%.^7,8 This was possibly caused by the aortic valve recoil phenomenon, suggested by the acute-phase hemodynamic collapse, or by reversion of the echocardiographic indices of severe AS.^7,8,12–14 One of the possible mechanisms of valve recoil is insufficient valvuloplasty, with the balloon inflation procedure performed only 2 or 3 times with conventional retrograde BAV. In fact, commercially available balloons for retrograde BAV can usually be inflated 2 or 3 times as per the instructions on the products. To reduce the valve recoil phenomenon in the present study, we inflated the balloon a median of 18 (12–26) times, with gradual upsizing of the balloon. The rationale of multiple inflations with gradual upsizing of the balloon is based on evidence from the orthopedic or sports medicine arena that muscle stretching can prevent patients from injury because of improvements in the range of motion and reductions in muscle and tendon stiffness.²⁰ This implied that multiple inflations with gradual upsizing of the balloon might be able to avoid acute valve injury and prevent the acute recoil phenomenon caused by valve stretching. Therefore, we speculated that a stepwise multiple-inflation procedure was the key to preventing the valve recoil phenomenon, and it may have contributed to achieving the relatively favorable outcomes compared with conventional BAV.

Safety of the New BAV Procedure

In our study we did not experience any significant periprocedural complications such as symptomatic cerebral or cerebellar infarction, AR or MR, annulus rupture, cardiac tamponade, or major bleeds. Conversely, asymptomatic cerebral or cerebellar infarction occurred in 8 patients (42.1%) on DWI. Periprocedural stroke is one of the most important issues concerning not only BAV, but also TAVI.^3,5–8 It has been shown that aortic arch atheroma is an independent predictor of cerebral infarction.²¹ Considering that previous studies have shown high rates of silent cerebral infarction detected by DWI post-TAVI (77–84%),^21,22 42.1% asymptomatic silent infarction may be acceptable in the current clinical setting. The antegrade transseptal approach is expected to decrease the incidence rate of periprocedural cerebral and cerebellar infarctions, because large devices never cross the aortic arch during the antegrade BAV procedure. Although a major concern with multiple inflations of the balloon is the possibility of scattering degenerative particles, including calcified particles derived from aortic valve leaflets, our results of a relatively low incidence of silent stroke still suggest that aortic arch atheroma is still the most important origin of stroke, as previously reported.²¹

The complication rates of AR or MR, annulus rupture, cardiac tamponade, or major bleeding were all 0.0% in our study. Although the small study population and the lack of a control group did not allow us to statistically evaluate procedural safety, the observed reduction in the incidence of complications with the biplane-TEE guided antegrade transseptal approach accompanied by the protocol of multiple inflations with gradual upsizing of the balloon may be comparable with the results of previously reported studies.^7,8,12–14 For example, a previous study reported a 1.7% incidence rate of acute AR, with 50% of this incidence occurring just after the first inflation of the balloon.^21,23 We speculate that our protocol of gradual upsizing of the balloon by inflation under biplane-TEE monitoring contributed to avoiding acute AR caused by a forced excessive valve dilatation, as well as avoiding rupture of the annulus by an excessively oversized balloon.^5,7,24 Moreover, the antegrade approach has the potential to injure the mitral valve apparatus, which results in acute MR; the Brockenbrough procedure for the transseptal approach has a risk of cardiac tamponade. However, real-time 3D Live-mode and biplane-TEE guidance in combination with fluoroscopy may contribute to preventing injury to the mitral valve apparatus, or cardiac tamponade. The risk of a major bleed in the present study was mitigated by use of the venous system (femoral vein) for the antegrade BAV procedure. Lastly, regarding hemodynamic stability during the procedure, we experienced some cases of hemodynamic instability and significant decrease of blood pressure during crossing of the balloon through the mitral valve and subvalvular apparatus. In these situations, TEE detected a temporary increase of MR, which could be addressed by catheter manipulation, and we believe that these events suggest the importance of TEE monitoring for a safe procedure. In addition, rapid pacing during balloon inflation provoked a significant decrease of blood pressure as expected. However, because the inflation time for the INOUE-BALLOON catheter is extremely short, this is one of the advantages of the antegrade approach using the INOUE-BALLOON catheter.

Clinical Implications

In this study, we demonstrated the safety and efficacy of biplane-TEE guided antegrade transseptal multiple-inflation BAV. We used a novel and unique combination of 3 approaches: (1) median of 18 inflations with gradual upsizing of the balloon vs. 2–3 inflations with a similar sized balloon in the conventional procedure; (2) an antegrade transseptal approach vs. retrograde transaortic approach in the conventional procedure, and (3) using simultaneous biplane mode of 3D-TEE guidance vs. fluoroscopy-only guidance in the conventional procedure. Each approach contributed to the achievement of relatively favorable outcomes in our study, as discussed. Unfortunately, no recent improvements have been reported compared with the results from the 1990 s on outcomes or complication rates following BAV, despite advancements in interventional devices.^7,8,12–14 This is partly because of a lack of any major technical change in the BAV procedure. Thus, the next challenge is to focus on developing new techniques for BAV to overcome the high mortality and complication rates associated with it. Hence, biplane-TEE guided antegrade multiple-inflation BAV could be a therapeutic option for the management of acute heart failure, or in the preparation for noncardiac surgery, or as a bridge therapy for TAVI or SAVR in patients with severe AS. We believe that the multiple-balloon inflation was the most important contribution to the low incidence of cardiac death. Because the antegrade approach enabled us to perform multiple inflations, we think these 2 steps are essential and the 3D Live-mode-TEE or simultaneous biplane mode of 3D-TEE guidance is optional even though it can enhance the safety and efficacy. We also believe that our safe procedure gives every interventional cardiologist the opportunity to bridge their patients with severe AS to TAVI even after acute hemodynamic collapse. However, we should also note that a team-based comprehensive approach is mandatory in treating patients with structural heart disease and that patients should ideally be treated in limited certified institutions if applicable. Large-scale randomized control trials are warranted to confirm our results.

Study Limitations

Firstly, our study was a single-center retrospective observational study, enrolling a small number of patients. Secondly, we did not compare the safety and efficacy of biplane-TEE guided multiple-inflation BAV with fluoroscopy-guided, antegrade or retrograde conventional BAV, with or without conventional 2D-TEE. To assess the safety and efficacy of our new procedure accurately, a direct comparison is needed and is the objective of a future study. From this point of view, our study is a hypothesis-generating study. With these limitations, our data should be interpreted carefully. However, it was notable that the highest margin of the 1-year mortality (35.1%) in the present study was comparable with those in previous studies, which ranged from 30% to 34%.^7,8 Because available data regarding the safety and efficacy of biplane-TEE guided antegrade multiple-inflation BAV are very limited, our results may provide physicians with new insights into BAV, and could contribute to advancement in interventional cardiology.

Conclusions

Biplane-TEE guided antegrade multiple-inflation BAV has the potential to improve periprocedural survival in patients with severe AS, without increasing complications in comparison with conventional retrograde BAV, and could be a therapeutic bridging option for TAVI in high-risk AS patients.

Acknowledgments

We express our heartfelt gratitude to the team members at our hospital, the SUNRISE Lab (http://sunrise-lab.net/), and the Japan Society of Clinical Research (http://www.japanscr.org/) for their dedicated support.

Conflict of Interests / Funding / Financial Relationships

None.

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