Mid-Term Outcomes of Aortic Valve Repair Without Aortic Root Replacement: A Single-Center Experience

Background Aortic valve (AV) repair is a challenging procedure due to its complexity, lower reproducibility, and steep learning curve. To examine its durability and validity, we investigated mid-term outcomes following AV repair without aortic root replacement. Methods Between March 2007 and May 2018, we retrospectively identified 14 patients who underwent AV repair without aortic root replacement at our institution. We investigated their baseline characteristics and postoperative outcomes, including the reoperation rate due to aortic regurgitation (AR) recurrence. Furthermore, we divided them into two groups: those who required reoperation due to AR recurrence (Group R) and those who did not require reoperation (Group F), and statistically compared them. Results The median age was 52.5 years (IQR: 42.0-60.8), with 11 male patients (78.6%). Eight patients (57.1%) had a bicuspid AV. Five cases (35.7%) underwent reoperation due to AR recurrence during a median follow-up period of 5.5 years. There were no significant differences in baseline characteristics between Group R (n=5, 35.7%) and Group F (n=9, 64.3%), including AR etiology, AV repair procedure, and intraoperative AR grade after the final declamp. All cases in Group R had at least mild to moderate AR on the echocardiogram before discharge. Regarding the AR grade before discharge, Group R had a significantly higher grade than Group F (p = 0.013). Conclusions The indication for AV repair for AR might need to be reassessed due to the considerable mid-term reoperation rate. Cases of AV repair with more than mild AR at discharge should be carefully monitored, as they are likely to require future reoperation for AR.

Current controversies in aortic valve-preserving surgery

The clinical outcome of severe aortic regurgitation (AR) remains suboptimal, but surgery has been shown to have survival benefit over medical therapy. Postoperative survival is inferior in patients with reduced left ventricular function, and therefore early surgical intervention is recommended. Aortic valvuloplasty (AVP) is an attractive option to avoid the major drawbacks of prosthetic valves but has not been widely adopted. The etiology of AR is classified functionally into three groups: normal leaflet motion (type I), cusp prolapse (type II), and restriction (type III). Type I with dilatation of the sinus of Valsalva (type Ib) can be repaired by aortic valve reimplantation or aortic root remodeling with similar valve stability. Type I with dilatation of the aortic annulus (type Ic) can be managed by annuloplasty. Type II can be corrected by plication or resuspension techniques. Pericardial patch is necessary in AVP for type Id (perforation/fenestration) and type III but is associated with risk of recurrence. Bicuspid aortic valve is classified according to commissure angle: symmetrical, asymmetrical, and very asymmetrical. Tricuspidization is recommended for repair of very asymmetrical valves to avoid postoperative stenosis. Recent progress has achieved similar reoperation rates between bicuspid and tricuspid aortic valve repair. For Marfan syndrome, valve-sparing root replacement is advantageous compared to Bentall operation regarding late survival, thromboembolic and hemorrhagic events, and endocarditis. Similar findings have been reported in acute aortic dissection. Both remodeling and reimplantation procedures provide similar favorable outcomes in these settings. Recent advances in AVP are summarized by quantitative assessment of cusp configuration (effective height and geometric height), graft size decision, use of template to cut the graft, and videoscopic assessment of post-repair cusp configuration. Due to these advances, AVP shows superior results to replacement surgery. Further concrete evidence with larger case volumes and longer observation periods are necessary to popularize AVP.

Current trends in aortic valve-preserving surgery

The natural history of aortic regurgitation is not as benign as once believed, even in asymptomatic patients with preserved left ventricular function. Aortic valve surgery can prolong survival in these patients. However, both mechanical and biological aortic valve replacement have major disadvantages, especially in young patients. Aortic valve-preserving surgery has attracted a great deal of attention because it has a significant survival benefit over replacement. Nonetheless, aortic valve-preserving surgery has not been widely adopted due to the complexity of the technique and assessment (i.e., long learning curve). With recent technical and theoretical advances, aortic valve-preserving surgery has increasingly been performed with better outcomes, and therefore earlier surgical intervention in cases of aortic regurgitation has been considered. Recent advances in aortic valve-preserving surgery include repair-oriented classification of the etiology of aortic regurgitation, objective assessment of the cusp configuration (i.e., effective height and geometric height), use of aortic annuloplasty, introduction of two reproducible valve-sparing root replacement procedures (i.e., aortic valve reimplantation and aortic root remodeling techniques), standardization of aortic valve-preserving surgery, and assessment of cusp configuration with aortoscopy. A number of prospective multicenter studies are currently underway and will clarify the role of aortic valve-preserving surgery in the treatment of aortic regurgitation in the near future.

Anatomy of the aortic root: implications for aortic root reconstruction

Since the introduction of valve-preserving root replacement and aortic annuloplasty, precise understanding of the aortic root anatomy has emerged as a key to successful aortic valve-preservation surgery. Fundamentally, surgeons need to know the precise anatomical definition and structure of the aortic root, including its normal dimensions, know the anatomy of the coronary arteries, and understand the cardiac conduction system. Surgeons must be able to clearly distinguish normal and abnormal structures, and recognize the effects of aortic valve regurgitation or root expansion on dimensions and geometric relationships within the aortic root. Possessing a detailed understanding of the aortic root, surgeons can select appropriately sized grafts and achieve optimum annular fixation. This review covers the essentials of aortic root anatomy and provides tips for correct and safe performance of aortic valve-preservation surgery with a view toward durable late outcomes.

In vivo testing of an intra-annular aortic valve annuloplasty ring in a chronic calf model

OBJECTIVE

To increase applicability and stability of aortic valve repair, a three-dimensional aortic annuloplasty ring has been developed for intra-annular placement. The goal of this study was to test the safety of this device with in vivo implantation in the calf model.

METHODS

In 10 chronic calves, the HAART annuloplasty ring was sutured to the aortic valve annulus using cardiopulmonary bypass. The animals were recovered and followed for 1-2 months. Serial echocardiography was used to evaluate valve competence, and contrast aortograms and CT angiograms were obtained in selected animals. After completion of follow-up, each animal was euthanized, and aortic endoscopy was performed under water distension in five. Full autopsies with histologic examinations were performed.

RESULTS

All animals survived surgery. Two were euthanized in the first week for complications, and the remaining eight calves were followed uneventfully for the 1-2 months. Serial echocardiography showed completely competent valves in all but one animal, in which the ring was intentionally up-sized to test the sizing strategy. Contrast aortographic and CT angiographic findings were similar to the echocardiograms. Postmortem examination showed proper seating of all rings with endothelialization at 1-2 months. All valves demonstrated good leaflet coaptation and no abnormalities.

CONCLUSIONS

In vivo testing of a three-dimensional aortic annuloplasty ring in a chronic calf model proved to be very successful and safe. Using the sizing and implant strategies developed, human trials seem indicated.