It is commonly believed that the size of the aortic annulus, and thus the size of the aortic prosthesis that can be implanted, depends on the patient’s height; however, the actual requirement is determined by their volume. Thus, patient-prosthesis mismatch (PPM) occurs when the implanted prosthesis size fails to meet the patient’s cardiac output requirements, leading to increased transvalvular gradients. This condition impacts the left ventricle, causing overload, hypertrophy, and eventual dysfunction, increasing morbidity and mortality associated with both the procedure and postoperative course. Younger patients and those with pre-existing ventricular dysfunction are most susceptible to PPM. Significant debate surrounds effective orifice area (EOA) measurements, with considerable variability in reported values among manufacturers. Furthermore, various aortic root enlargement techniques exist without a clear consensus on the optimal approach, with the Nicks technique being the most popular despite its limited efficacy. Recently, in 2020, Dr. Bo Yang described a novel “Y”-incision method for aortic root enlargement. Today’s article provides a brief overview of the technique, along with short-term results from the first 119 patients. 

For the surgical technique, the following steps are recommended: 

• Cannulate the aorta near the innominate artery to facilitate the subsequent reconstruction of the ascending aorta. 
• Perform a transverse aortotomy either entirely, 2-2.5 cm above the sinotubular junction, or partially. 
• Following excision and debridement of the diseased aortic valve, make an incision between the commissure of the noncoronary and left coronary sinuses, extending to the aortomitral junction. Extend the incision in a “Y” shape at the aortomitral junction, running parallel to the aortic annulus towards the nadirs of the annular segments of both aortic leaflets, reaching the fibrous trigones on either side. It is crucial to avoid fully severing the fibrous trigones, stopping approximately 2-3 mm from the myocardium on the left side and the membranous septum on the right. This maneuver significantly opens the aortic root. If the incision does not reach the fibrous trigones, the patch for enlargement will be too small and potentially insufficient to achieve the desired prosthetic size. 
• Measure the distance between both nadirs and cut a rectangular Dacron patch approximately 5 mm wider to accommodate the suture line. Typically, the patch measures around 3.75 cm or more; the wider the patch, the greater the root enlargement. 
• Suture the patch to the aortomitral junction/mitral annulus with a 4-0 monofilament suture, starting from the left trigone to the right. When reaching the nadirs of both cusps, the suture continues cranially towards the ascending aorta and the transverse aortotomy. 
• Insert the sizer and select the size that makes contact with all three nadirs of the enlarged root, potentially increasing the prosthetic size by approximately three units over the initial size. Once the appropriate size is chosen, mark the plane and height for the sutures on the Dacron patch, ensuring proper patch extension to locate the correct plane. 
• Once the prosthesis size is determined, orient the struts so that one lies between the right-left commissure, thereby preventing coronary ostia obstruction. The height of the valve anchoring points on the patch should match those at the level of the divided commissure of the noncoronary-left coronary sinuses, aligning with the commissures of the remaining sinuses of Valsalva. If the anchoring points are placed too low, achieving an adequate prosthetic size may be limited, as the technique primarily enlarges the root rather than the aortic annulus. As a result, part of the patch and most of the anchoring suture will be ventricularized. Furthermore, forcing an oversized prosthesis in this scenario may obstruct the right coronary ostium, given its anterior and cranial angulation. Conversely, if the valve anchoring points are placed too high, the prosthesis may tilt posteriorly and cranially, jeopardizing the left coronary trunk and compromising valve hemodynamics by not aligning coaxially with the left ventricular outflow tract. It is essential to distribute the valve anchoring points on the patch uniformly so that one post is positioned between the left and right coronary sinuses’ commissures. In the case of a purely bicuspid valve, the post should be positioned midway between the coronary ostia. 
• Begin by tying the sutures between the nadirs of the noncoronary and left coronary cusps to prevent paravalvular leaks, as this is the lowest point of the aortic annulus. 
• Finally, close the aortotomy using the “roof” technique: trim the Dacron patch into a triangular shape with the tip about 2 cm above the posterior post of the bioprosthesis. This approach prevents kinking between the aorta and the enlarged root, eliminates the sinotubular junction, and prepares the area for future percutaneous valve-in-valve (ViV) procedures, reducing the risk of a Valsalva sinus sequestration and undesirable coronary occlusion. 

In the first 119 consecutive cases with “Y”-incision root enlargement, the median patient age was 65 years, with 67% being female and one-third being reoperations. There were two cases of acute endocarditis. The preoperative mean transvalvular gradient was 36 mmHg, with a mean native valve area of 0.9 cm². The median aortic annulus size increased from 21 mm to 29 mm following root enlargement. There was one postoperative death, one stroke, and two cases of complete atrioventricular block requiring pacemaker implantation (one in a patient operated on for active endocarditis with a Gerbode-type fistula: aortic root-right atrium). No cases of renal failure requiring renal replacement therapy, mediastinitis, or bleeding were reported. A median follow-up of one year confirmed via CT scan that the aortic root had expanded from 27 mm to 40 mm. Follow-up echocardiograms showed a mean transvalvular gradient of 6 mmHg with a valve area of 2.2 cm². 

The authors, including Dr. Bo Yang, conclude that “Y”-incision aortic root enlargement is a safe and more effective technique than classical methods. 

COMMENTARY: 

The first complications due to PPM were described in 1978. Since then, the importance of EOA indexed to the patient’s body surface area has gained attention. PPM is considered moderate if this ratio is <0.85 cm²/m² and severe if <0.65 cm²/m². Updated definitions in the VARC3 guidelines now consider PPM moderate if <0.70 cm²/m² and severe if <0.55 cm²/m² for patients with a BMI >30 kg/m². The degree of PPM significantly impacts short- and long-term morbidity and mortality. Severe PPM leads to increased readmissions for heart failure post-intervention, accelerated bioprosthesis deterioration, a 56% increase in perioperative mortality, and a 26% increase in mortality over time. This mortality increase is most notable in patients with left ventricular dysfunction. In cases of moderate PPM, the literature presents contradictory results, making root enlargement to prevent it still a debated issue. 

Root enlargements can be classified as anterior and posterior. The anterior enlargement, the Konno-Rastan procedure, uses an incision through the right coronary sinus and interventricular septum, allowing a size increase of up to three or four units. Due to its technical complexity, it is rarely used in acquired heart disease and is mostly reserved for congenital heart disease with multilevel stenosis. Posterior enlargements include the Nicks procedure, the Manouguian procedure, and its variant, the Núñez procedure. The Nicks technique extends the aortotomy through the noncoronary sinus. Conversely, the Núñez and Manouguian techniques extend the incision through the commissure between the left and noncoronary sinuses, with the Núñez stopping at the aortomitral junction, whereas the Manouguian proceeds to the anterior mitral leaflet, sometimes requiring left atrial roof opening. Nicks and Núñez enlargements typically allow for a one-size prosthetic increase as they only affect the root and not the aortic annulus. The Manouguian procedure achieves a two- to three-size increase but risks distorting mitral valve function, as it is the only technique that entirely divides and enlarges both the annular and basal rings, including the aorto-ventricular junction. Yang’s procedure, like the others, does not enlarge the basal ring of the aortic root. However, this is not an issue, as there are no documented cases of subvalvular stenosis. Basal rings of the aortic root are generally normal-sized even in the most stenotic valves and usually do not limit flow. 

“Y”-incision root enlargement allows for a multi-size prosthetic increase, addressing short-term PPM and potentially averting it in future ViV procedures, as outcomes for valves smaller than 23 mm are suboptimal. Nevertheless, the technique has limitations. The transition from the aortomitral junction to the anterior mitral leaflet may not always be clear, and suturing in this area could jeopardize mitral valve function by restricting the anterior leaflet. Additionally, the rectangular Dacron patch may distort the coronary arteries, leading to kinking. Finally, it is uncertain whether this enlargement may ultimately distort the root, making TAVI prosthesis implantation unfeasible due to potential coronary trunk obstruction. 

Only time will tell if these concerns prove real or are mere cautionary considerations. However, it is clear that our duty is to continue delivering the excellent outcomes of surgical aortic valve replacement we have achieved to date. PPM diminishes bioprosthetic durability and freedom from reintervention rates. The only setting where the aortic root can be enlarged to prevent it is in the operating room, and the decision rests in our hands. 

REFERENCE 

Hassler KR, Monaghan K, Green C, Yang B. How-I-Do-It: Aortic Annular Enlargement – Are the Nicks and Manouguian Obsolete? Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2024;27:25-36. doi: 10.1053/j.pcsu.2023.12.005.