Consequences of Underexpansion of a Percutaneous Aortic Valve Bioprosthesis

ABSTRACT: Transcatheter aortic valve implantation has been shown to be an effective and reproducible therapy for severe aortic valve stenosis. Device performance and short-term outcomes of well-deployed prostheses have been extensively investigated and discussed; however, these endpoints have not yet been reported in cases characterized by suboptimal expansion. We describe a case of CoreValve self-expanding prosthesis underexpansion, reporting data on prosthesis performance and short-term clinical outcome. J INVASIVE CARDIOL 2010;22:E86–E89 Key words: aortic stenosis, transcatheter, prosthesis Transcatheter aortic valve implantation (TAVI) is becoming a real alternative to conventional “open-chest” valve replacement in high-surgical risk patients affected by severe aortic stenosis (AS). Although several prostheses have been developed in the last few years, only two devices are in an advanced stage of clinical evaluation and received the CE mark in the European Community: the balloon-expandable Edwards-SAPIEN™ (ES) aortic valve (Edwards Lifesciences, Irvine, California) and the 18 Fr third-generation of self-expandable CoreValve Revalving System® (CRS) prosthesis (Medtronic, Inc., Minneapolis, Minnesota).^1–4 The long-term durability of these two valves has undergone in-depth laboratory testing. Moreover, several studies have shown excellent short- and mid-term outcomes of TAVI in terms of prosthesis performance, incidence of complications, survival and improvement in quality of life. ^1–5 However, the prosthesis performance (frame and biological valve) in cases characterized by suboptimal expansion inside a calcified native valve is unknown. We describe a case of a CoreValve prosthesis underexpansion, analyzing the early device performance and clinical outcomes. Case Report. An 83-year-old male with a diagnosis of severe AS associated with chronic atrial fibrillation, chronic renal failure (creatinine clearance 34.1 ml/minute), New York Heart Association (NYHA) functional class III and a logistic EuroScore of 19.9% was referred to our Institute for TAVI. A previous coronary angiogram showed subcritical stenoses of the right coronary artery and first diagonal branch. Transthoracic echocardiography (TTE) confirmed the presence of severe AS, with a mean transvalvular gradient of 50 mmHg, an aortic valve area of 0.50 cm2 and a left ventricle ejection fraction of 25%. Due to the unstable hemodynamic and clinical status, palliative aortic balloon valvuloplasty was performed with an undersized balloon (16 x 50 mm TyShak, Numed, Hopkinton, New York), reducing the peak-to-peak transvalvular gradient from 60 mmHg to 35 mmHg. Fourteen days later, TAVI was performed under fluoroscopic and angiographic guidance using local anesthesia and mild sedation and an 18 Fr CRS (Figure 1). After the placement of a 10 Fr Prostar XL vascular suture-mediated system (Abbott Vascular, Redwood City, California) in the left femoral artery, aortic valvuloplasty was performed during right ventricular pacing with a 22 x 40 mm Nucleus balloon catheter (Numed, Inc., Hopkinton, New York) (Figure 2). Subsequently, the 26 mm CoreValve self-expanding prosthesis was positioned across the native valve and deployed in a correct position with respect to the aortic annulus (Figure 3A). The procedure was carried out using the standard technique4 without complications. Once complete deployment of the 26 mm prosthesis was achieved, the angiogram executed in the right anterior oblique projection showed a suboptimal bioprosthesis expansion (Figure 3B). Aortography proved only a mild paravalvular leakage without intraprosthetic regurgitation and left cardiac catheterization denied hemodynamic consequences (left ventricular pressure 160/0/15 mmHg, aortic pressure 150/80 mmHg,) and enduring transvalvular gradient; nevertheless, in order to achieve optimal expansion of the prosthesis, we decided to perform postdilatation with a 22 x 40 mm Nucleus balloon under rapid pacing, but this attempt was not successful. Therefore, since the patient was in stable hemodynamic condition, we left the prosthesis underexpanded. TTE performed at the end of the procedure confirmed full functionality of the prosthesis, with mild paravalvular leakage at the site of underexpansion.The patient was discharged in NYHA Class II 6 day after the procedure and a computed tomography angiogram (CTA) performed 30 days later showed the CoreValve underexpansion without any shape modification or migration (Figures 4 A and B). At 6-month follow up, the patient was in NYHA functional class II and TTE showed sustained good prosthesis performance without a transvalvular gradient and only mild periprosthetic leakage (Figure 5). Improvement in the patient’s quality of life, as assessed by the Short Form 12-Item Health Survey® (SF-12) Version 2.0,5 was also noted. Discussion. Short- and mid-term performance and clinical outcomes with an ES and CRS bioprostheses have been extensively investigated and discussed. ^1–4 This is the first time that outcomes following percutaneous prosthesis underexpansion have been reported. TAVI is generally performed in patients with severe native valve calcification, and pre-balloon valvuloplasty might be not sufficient to optimally prepare the aortic root for the bioprosthesis implantation; therefore, the circumstance of suboptimal device expansion following percutaneous valve deployment could be more frequent than expected. Unfortunately, to date, the literature lacks data indicating the incidence of this condition. After implantation of 89 CoreValve prostheses, we observed permanent underexpansion in 3 patients (3.3%). In all cases, postdilatation was unsuccessful. CTA was performed within 1 month from the procedure and close clinical and echocardiographic follow up were realized. To explain the suboptimal positioning of the CRS prosthesis, we can speculate that the native valve was an extremely severely calcified or functionally bicuspid valve. We had already suspected one of these conditions when palliative valvuloplasty was performed 14 days before TAVI with an undersized balloon (Figure 2) and during valvuloplasty before prosthesis deployment (Figure 6). At these time points, the waist of the balloon when it was inflated was notable (Figure 6). Postdilatation was performed in the hopes of better expanding the prosthesis, but it was unsuccessful because it was not possible to expand the underexpanded side of the frame. The Nucleus 22 x 40 mm balloon was utilized because a larger diameter could potentially damage the prosthetic aortic cusps. Despite the eccentric expansion (Figures 3 and 4), the prosthetic valve performed well, with a mean echocardiographic gradient of 10 mmHg (Figure 5) and a left ventricular ejection fraction of 35%; no intravalvular regurgitation and only a tiny perivalvular leakage were noted. The patient showed clinical improvement at 6-month follow up, considering both the NYHA class II and the quality of life. This case highlights the ductility of the self-expanding prosthesis and demonstrates how its functionality can remain excellent without evidence of fracture of the nitinol frame, even in cases of suboptimal deployment. Further studies and longer follow up periods are needed to assess the long-term outcomes of this condition.

References

1. Cribier A, Eltchaninoff H, Tron C, et al. Treatment of calcific aortic stenosis with the percutaneous heart valve: Mid-term follow-up from the initial feasibility studies: The French experience. J Am Coll Cardiol 2006;47:1214–1223. 2. Webb JG, Altwegg L, Boone RH, et al. Transcatheter aortic valve implantation: Impact on clinical and valve-related outcomes. Circulation 2009;119:3009–3016. 3. Piazza N, Grube E, Gerckens U, et al; on the behalf of the clinical centres who actively participated in the registry. Procedural and 30-day outcomes following transcatheter aortic valve implantation using the third generation (18 Fr) CoreValve ReValving System: Results from the multicentre, expanded\evaluation registry 1-year following CE mark approval. EuroInterv 2008;4:242–249. 4. Grube E, Buellesfeld L, Mueller R, et al. Progress and current status of percutaneous Aortic Valve Replacement: Results of Three Device Generations of the CoreValve® revalving system. Circ Cardiovasc Intervent 2008;1:167–175. 5. Ussia GP, Mulè M, Barbanti M, et al. Quality of life assessment after percutaneous aortic valve implantation. Eur Heart J 2009;30:1790–1796.

_____________________________________________________________________ From the *Division of Cardiology, Ferrarotto Hospital, University of Catania, Italy, and the §Excellence Through Newest Advances (ETNA) Foundation. Disclosure: Gian Paolo Ussia is a Proctor Physician for CoreValve. Manuscript submitted August 20, 2009, provisional acceptance given September 5, 2009, final version accepted September 10, 2009. Address for correspondence: Gian Paolo Ussia, MD, FSCAI, Director of Interventional Structural and Congenital Heart Disease Programme, Invasive Cardiology, Division of Cardiology – Ferrarotto Hospital, University of Catania, Catania, Italy. E-mail: gpussia@hotmail.com