Aortic annulus enlargement

Challenges facing surgeons

Aortic stenosis is one of the cardiac pathologies that most affects the world population, with its prevalence increasing with the aging of the population, reaching close to 10% in patients aged 80-90 years.

The barrier to blood flow, exercised by the stenotic valve, causes, over time, hypertrophy of the left ventricle with consequent deficit of filling and impounding of blood in the left atrium and pulmonary vessels, causing atrial dilation and pulmonary hypertension.

The definitive treatment for aortic stenosis is to replace the valve, resolving the blood flow barrier. This valve replacement can be done surgically or by transcatheter.

Legend : aortic valve ready to be deployed

 

In principle, the valve prosthesis size to be deployed is limited by the root of the aorta where the prosthesis will be attached. In addition, this can create a problem, as small valve prostheses for the patient’s body surface area (BSA) will cause a relative stenosis effect, similar to the effect of aortic stenosis. This effect is named patient-prosthetic mismatch (PPM), that is, mismatch, discrepancy between prosthesis size and patient’s BSA.

PPM in the aortic position is very harmful to the patient, with studies showing an increase in negative outcomes in the immediate postoperative period as well as in the late one.

For these cases of patients with a small aortic root and large body surface, the surgeon has in his arsenal the possibility of expanding the aortic root in order to accommodate a prosthesis with a valve orifice suitable for the patient.

The decision to enlarge the aortic root often takes place intraoperatively. Ideally, there should be debridement of all calcium deposits in order to measure which prosthesis can be placed. After measurement, if the available prosthesis does not have an adequate valve orifice for the patient’s BSA, the surgeon must choose to expand the aortic root. Attempts to place large valves in small aortic annuli can result in damage to the prosthesis, sections of the aorta, and even left ventricular outflow tracts.

There are three types of classic surgeries, two posterior (Nick and Manouguian) and one anterior (Konnan). The enlargement of the root of the anterior aorta is seldom used around the world, as it is a surgery of greater technical difficulty; however, it is the one that allows the largest increase in the aortic root.

Generally speaking, these are more complicated surgeries than simple aortic valve replacement. The surgeon classically enlarges the aortic incision, with a path through the non-coronary leaflet (Nick) or at the junction of the non-coronary leaflet with the left coronary (Manouguian), and sutures a pericardium patch starting in this region going to the aorta.

(Suggested video: https://www.youtube.com/watch?v=IeKB7M20jL8)

These are surgeries that involve a higher risk of bleeding, mitral valve injury, AV blocks. However, it is a risk worth taking for a few reasons:

As previously explained, aortic PPM is very harmful to the patient. It affects his or her life from the moment he leaves the operating room.

We live in an era of expansion of transcatheter procedures. These, despite being excellent in terms of little invasiveness, do not allow us to remove old valves, giving only the option of valve implantation inside other valves. With this, with each new valve in valve (ViV), the effective valve orifice decreases.

TAVR PPM also increases postoperative mortality. So it is extremely important, that in a first surgery, the largest possible prosthetic valve is implanted, aiming at ViV procedures in the future without causing PPM.

For isolated aortic valve replacement surgeries (that is, without concomitant revascularization or mitral valve replacement), enlargement of the aortic root does not increase perioperative mortality, even with a longer extracorporeal circulation time (p = 0.66 -> not significant).

Thus, it seems that the short, medium and long-term benefits of enlarging the aortic root outweigh the operative risks.

It is noteworthy that, as in any aspect of the surgical world, services that have a greater volume of aortic root enlargement surgery have better results.

For surgeons unfamiliar with the techniques, the challenges of surgery must be considered when making the decision, putting in mind that for the patient to benefit from the enlargement, he must overcome the surgical moment.

Suggested literature:

1- Eveborn GW, Schirmer H, Heggelund G, Lunde P, Rasmussen K. The evolving epidemiology of valvular aortic stenosis. Heart. 2013;99(6):396. Epub 2012 Sep 2.

2 – Sá MPBdO, de Carvalho MMB, Sobral Filho DC, Cavalcanti LRP, Rayol SdC, Diniz RGS et al. Surgical aortic valve replacement and patient–prosthesis mismatch: a meta-analysis of 108.182 patients. Eur J Cardiothorac Surg 2019.

3 – Sá MPBOCavalcanti LRPSarargiotto FASPerazzo ÁMRayol SDCDiniz RGSSá FBCAMenezes AMLima RC. Impact of Prosthesis-Patient Mismatch on 1-Year Outcomes after Transcatheter Aortic Valve Implantation: Meta-analysis of 71,106 Patients. Braz J Cardiovasc Surg.2019 Jun 1;34(3):318-326.

4 – Sá MPBO, Carvalho MMB, Sobral Filho DC, Cavalcanti LRP, Diniz RGS, Rayol SC, Soares AMMN, Sá FBCA, Menezes AM, Clavel MA, Pibarot P, Lima RC. Impact of surgical aortic root enlargement on the outcomes of aortic valve replacement: a meta-analysis of 13.174 patients. Interact CardioVasc Thorac Surg 2019.

 

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