Bioprosthetic Valve Fracture for Early Severe Prosthesis Mismatch After SAVR

Abstract: Background. Patient prosthesis mismatch (PPM) is an iatrogenic complication that occurs in patients who undergo surgical aortic valve replacement (SAVR). PPM occurs when the implanted surgical valve has an effective orifice area (EOA) that is too small for the patient, resulting in a gradient across the valve despite an otherwise normally functioning prosthesis. PPM has been associated with mid- and long-term increased morbidity and mortality. When this occurs, repeat SAVR with root enlargement and implantation of a larger prosthesis is traditionally employed; however, this approach involves the risks of morbidity and mortality of redo surgery, which may be prohibitive in critically ill or medically complex patients. Bioprosthetic valve fracture (BVF), where high-pressure balloon inflation is employed to fracture the surgical valve sewing ring to increase the EOA, has been used as an adjunct for valve-in-valve (transcatheter aortic valve in surgical aortic valve [TAV in SAV]) procedures for degenerated surgical valves to increase EOA, but has not yet been reported as standalone therapy for early PPM after SAVR. Case Presentation. We present a case of a 41-year-old male (body surface area, 2.3 m²) who presented 4 months after SAVR with a 21 mm surgical valve (Magna Ease, true inner diameter, 19 mm) with severe PPM (mean gradient, 43 mm Hg) despite normal functioning valvular prosthetic leaflets, associated with debilitating symptoms. This patient was deemed high risk by the heart team, and was successfully treated with TAV in SAV (26 mm Evolut R) and concomitant high-pressure bioprosthetic valve fracture (BVF) with a 22 mm high-pressure balloon. The patient tolerated the procedure well; mean gradient was 5 mm Hg post BVF and prompt resolution of symptoms was seen. His postprocedure recovery was uneventful and his symptoms resolved, allowing him to return to work within a week of his hospital discharge. BVF associated with TAV in SAV appears to be a feasible approach for treatment of severe symptomatic PPM even in the early postoperative period with otherwise normally functioning prosthesis.

J INVASIVE CARDIOL 2020;32(7):E182-E185.

Key words: patient prosthesis mismatch, transcatheter intervention, valve fracture

Patient prosthesis mismatch (PPM) was initially reported in 1978^1,2 as a complication that arises after valve replacement, when the effective orifice area (EOA) of the implanted prosthetic valve is too small in relation to the patient’s body surface area.^1,2 Increased transvalvular gradients and risk of ventricular outflow obstruction typically result, and are often accompanied with persistent, often debilitating symptoms with potential need for reintervention.^1,2

The use of the EOA index (EOAi), the value of the EOA divided by the body surface area, has become one of the most frequently used tools for classifying the severity of PPM.^1-4 Several factors are thought to potentially affect the predictive accuracy of EOAi, such as obesity, annular accumulation of calcium, and type of valve used.^2-5 Despite increasing attention toward recognition and diagnosis of PPM, the incidence of moderate PPM has been previously documented as high as 70%,^2-5 with the incidence of severe PPM approximately 10% in patients who undergo surgical (SAVR) or transcatheter aortic valve replacement (TAVR).^3-5 Patients with moderate or severe PPM after SAVR have been reported to have worsened postoperative outcomes, including reduced left ventricular (LV) mass regression and lower overall rates of survival compared to those without PPM following SAVR.^5,6 In certain clinical contexts, TAVR may be preferable to SAVR in patients with a small aortic annulus to avoid increased risk of severe PPM after AVR.^6,7 

Bioprosthetic valve fracture (BVF) is a procedural method employed to facilitate valve-in-valve (ViV) strategies such as TAV in SAV, or more recently, TAV in TAV,^8,9 where the intentional fracture of the original valve is performed using inflation of a high-pressure balloon.⁸ Fracture of the original valve allows for optimal expansion of the replacement valve,⁹ thereby reducing transvalvular gradients, and increasing EOA.^8,9 The long-term effect of BVF on durability of the replacement valve has not yet been proven; however, in small case series, it appears to be a safe and feasible option for addressing PPM.^8,9

Case Presentation

A 41-year-old Caucasian male (body mass index, 33.61 kg/m²; body surface area, 2.28 m²) was referred to our institution for evaluation of persistent symptoms of dyspnea, fatigue, and continuous chest discomfort. His history was notable for a bicuspid aortic valve with associated ascending aortic aortopathy; he had previously undergone a valve sparing root repair with a 26 mm Terumo aortic vascular graft 5 years prior. Four months prior to the current presentation, he presented with severe aortic insufficiency in the native valve; he underwent repeat open surgical procedure with AVR. Intraoperatively, extensive scar and calcification of the root made root enlargement problematic and the largest valve that could be placed was a 21 mm Magna Ease bioprosthetic valve (Edwards Lifesciences). His postoperative course was uneventful, and the patient was discharged on postoperative day 5. No echocardiogram was done in the immediate postoperative period.

At the time of his outpatient follow-up, the patient’s symptoms were stable at rest, but he noted exertional dyspnea with any activity. He was unable to fully participate in cardiac rehabilitation and was not capable of returning to work as a building contractor. Outpatient evaluation included cardiac computed tomography angiography (Figures 1A and 1B), which showed no evidence of hyperattenuation leaflet thrombosis (HALT) and confirmed valve sizing; transthoracic echocardiography (TTE) was performed 6 weeks after SAVR, with ejection fraction of 70%, mean gradient of 43 mm Hg, and maximal velocity (Vmax) of 400 cm/s, with calculated EOA of 1.19 cm and EOAi of 0.52, consistent with severe PPM (Figures 1C-1F). Transesophageal echocardiography (TEE) showed normal prosthetic valve leaflet function, but revealed an elevated outflow tract Vmax of 425 cm/s. Transseptal left and right heart catheterization with simultaneous pressure measurements showed evidence of moderate to severe aortic stenosis and coronary arteries free of major stenoses or blockages (Figures 1G and 1H). Coronary obstruction risk was predicted to be low with catheter-based therapies, and vascular access was acceptable.

He was evaluated by a multidisciplinary heart team consisting of cardiac surgeons, interventional cardiologists, and coordinator staff. He was determined to be at high risk for surgical complications given his history of 2 prior open surgical procedures and difficulties seen at prior surgery. BVF with TAVR was proposed as an alternative to surgical root enlargement; a self-expanding catheter valve with supra-annular design was felt to offer the most favorable hemodynamics.

Standard techniques for TAVR² and BVF^2,3 were employed. Access was obtained in the left femoral artery and vein without complication, and a temporary pacing wire was placed from the right femoral vein. A 6 Fr pigtail catheter was then advanced from the left femoral artery to the ascending aorta. At the right femoral artery, percutaneous access was obtained, Perclose sutures (Abbott Vascular) were placed, and a placeholder 14 Fr sheath was placed in the right femoral artery. The aortic valve was then crossed in a retrograde fashion using a straight wire and diagnostic 6 Fr AL1 catheter. Simultaneous LV and aortic (Ao) pressures were recorded, and noted to be 140/15 mm Hg (LV) and 90/62 mm Hg (Ao).The pigtail was then removed from the ventricle over a stiff exchange wire and the 16 Fr sheath was exchanged over the wire for the 16 Fr inline sheath. A 26 mm Evolut R valve was placed without complication. The valve was carefully placed to ensure optimal placement with high implant to optimize hemodynamics and the valve was deployed with slow ventricular pacing (Figure 2A).

Intraprocedural TTE performed after valve deployment showed no aortic insufficiency or paravalvular leak and good function. Mean gradients had improved from 52 mm Hg to 24 mm Hg after valve implant; Vmax was 300 cm/s. Given normal leaflet motion in the surgical valve, improved gradients were likely attributable to supra-annular position of the self-expanding TAVR valve. As planned, BVF of the 21 mm Magna Ease bioprosthetic valve was performed with a 22 mm True balloon (C.R. Bard; Figure 2B) with a tactile, audible, and visible fracture of the valve (Figure 2C). Post-BVF mean gradients were assessed and noted to be 5 mm Hg by catheter (Figure 2D) and 9 mm Hg by echocardiography (Figure 2E). Given this result, the procedure was considered successful. The stent-valve delivery system was then removed over the wire. The large sheath was removed from the right and the two Perclose sutures were deployed. The patient was then taken to the postoperative recovery area, where he emerged from sedation without complications and recovered overnight in the cardiac surgery intensive care unit (ICU). 

On postoperative day 1, he was transferred out of the ICU, with repeat TTE showing mean gradients stable at 11 mm Hg. He remained hemodynamically stable, and was ambulating without chest pain, shortness of breath, weakness, or fatigue. At his 30-day follow-up as an outpatient, he remained symptom free, with repeat TTE showing ejection fraction of 70%, mean gradient of 13 mm Hg, pressure gradient of 26 mm Hg, and Vmax of 257 cm/s. He had also returned to work full time, and reported continued absence of symptoms at rest and with exertion.

Discussion

Patient prosthetic mismatch has been correlated with increased transvalvular gradients, need for reintervention secondary to valvular degeneration, development of secondary arrhythmias, decreased exercise tolerance, hospital readmissions, and patient-reported decreased quality of life.^2-4 Both short- and long-term mortality are associated with severe PPM^3,6,7 after SAVR. For severely symptomatic patients who cannot tolerate the risks of reoperative intervention, there are few therapeutic options and no currently available guidelines to determine when to proceed with an alternative transcatheter approach for surgical PPM management.

In early studies,^2,3 BVF appears to be a relatively safe and feasible therapy for relief of symptomatic and hemodynamically significant PPM when used as an adjunct to TAV in SAV for degenerated valve disease. The use of BVF and optimal integration into an algorithm as an adjunct therapy for TAV in SAV is not yet clear in the literature. There are no reported cases of BVF use in the early postoperative period in the setting of a normally functioning leaflet prosthesis.

We report a case of successful use of BVF as primary therapy for PPM in the early postoperative period with a transcatheter valve implant as an adjunct for BVF. There are several novel aspects of this report. Use of BVF, while not standard, is increasingly done as an adjunct for TAV in SAV in chronically degenerated valves; however, the average time to TAV in SAV procedure in the VIVID registry was 8.9 years.¹⁰ However, in this case, the implanted valve was functioning properly and only 4 months old, with no evidence of HALT and excellent motion on imaging. Therefore, the primary therapy here was BVF of severe early surgical PPM, and TAV in SAV in this case served as an adjunct for BVF. 

While early, highly symptomatic, severe PPM after SAVR is not often reported, it may be underdiagnosed, as echocardiographic data suggest severe PPM after SAVR in up to 11% of patients in the STS Registry database, with increased mortality.¹¹ Another retrospective series noted a 13% rate of severe PPM and an associated 5.2% 1-year mortality rate.¹² Reoperation carries a significant risk of morbidity and mortality. In this case, a young and highly active patient was symptomatic very soon after SAVR, unable to complete cardiac rehabilitation or return to work, prompting the need for reintervention in the early postoperative period. Surgical risk was high after 2 prior surgeries and the findings on last sternal entry. We demonstrate here that in patients who cannot tolerate the current standard of care (reoperative SAVR), BVF using a transcatheter approach to valve replacement is one potential option in the early postoperative setting after SAVR.

Study limitations. BVF is still a developing therapy and only recently began being captured as a data point in the TVT Registry; therefore, the incidence of complications in current practice is not known. More information will be needed on the potential long-term impact of in vivo valve fracture, including its effect on long-term performance of the replacement valve. The potential risks of BVF (ie, annular rupture, coronary obstruction, prosthetic valve embolization) must be weighed against the risk of surgical reoperation on a case-by-case basis, and this approach should be reserved for those at high or extreme surgical risk until more data are available. 

From Sentara Heart Valve and Structural Disease Center, Norfolk, Virginia. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted March 18, 2020, final version accepted March 31, 2020.

Address for correspondence: Paul Mahoney, MD, Director, Sentara Heart Valve and Structural Disease Center, Sentara Heart Hospital, 600 Gresham Drive, Norfolk, VA 23507. Email: Paul.mahoney.md@gmail.com

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