Defining the Efficacy of Aortic Root Enlargement Procedures: A Comparative Analysis of Surgical Techniques

Prosthesis-Patient Mismatch and Aortic Root Enlargement: Indications, Techniques and Outcomes

Prosthesis-patient mismatch (PPM) is defined as implanting a prosthetic that is insufficiently sized for the patient receiving it. PPM leads to high residual transvalvular gradients post-aortic valve replacement and consequently results in left ventricular dysfunction, morbidity and mortality in both the short and long term. Younger patients and patients with poor preoperative left ventricular function are more vulnerable to increased mortality secondary to PPM. There is debate over the measurement of valvular effective orifice area (EOA) and variation exists in how manufacturers report the EOA. The most reliable technique is using in vivo echocardiographic measurements to create tables of predicted EOAs for different valve sizes. PPM can be prevented surgically in patients at risk through aortic root enlargement (ARE). Established techniques include the posterior enlargement through Nicks and Manouguian procedures, and aortico-ventriculoplasty with the Konno-Rastan procedure, which allows for a greater enlargement but carries increased surgical risk. A contemporary development is the Yang procedure, which uses a Y-shaped incision created through the non- and left-coronary cusp commissure, undermining the nadirs of the non- and left-coronary cusps. Early results are promising and demonstrate an ability to safely increase the aortic root by up to two to three sizes. Aortic root enlargement thus remains a valuable and safe tool in addressing PPM, and should be considered during surgical planning.

Aortic root widening: “pro et contra”

In patients with a small aortic annulus, the clinical benefits of aortic valve replacement depend on avoidance of patient-prosthesis mismatch as it is associated with reduced overall survival. Aortic root widening or enlargement is a useful technique to implant larger valve prosthesis to prevent patient-prosthesis mismatch. Posterior annular enlargement is the commonest technique used for aortic root enlargement. Consistent enlargement of the aortic root requires more extensive procedures like Manouguian or Konno-Rastan techniques. The patients commonly selected are younger patients with good life expectancy. However, caution is advised in applying this procedure in elderly patients, patients with heavily calcified annulus and when performing concomitant procedures. There is no definitive conclusion on the best material to use for the reconstruction of aortic annulus and aorta in aortic root enlargement procedures.

Aortic root enlargement: When and how

Aortic valve replacement is the definitive management for severe aortic stenosis. Intraoperatively, an aortic root enlargement (ARE) may be used to facilitate the implementation of a suitably sized prosthetic valve. This is to prevent patient prosthesis mismatch (PPM), a condition that causes a left ventricular outflow obstruction. There are four main techniques that are used to perform ARE, namely, Nicks, Manouguian, Nunez (modified Manouguian), and Kanno-Rastan procedures. They each involve incisions through different anatomical structures and allow a variety of valve sizes to be implanted. Studies prove that ARE effectively reduces the incidence of PPM. In addition, they show that there is no definitive link between ARE and perioperative mortality or other complications. There is a scarcity of literature exploring the comparative outcomes of each surgical technique. Therefore, further research is warranted for these procedures to be compared adequately. This review aims to summarise the available literature surrounding ARE with respect to three main questions. (1) What are the indications for ARE, (2) what surgical techniques exist to facilitate ARE, and (3) are there significant differences in patient outcomes when these surgical techniques are employed?

Computed tomography of dynamic changes of the aortic root during systole and diastole in patients with coronary artery calcification

PURPOSE

This study was done to investigate the dynamic changes of the aortic root during systole and diastole in patients with coronary artery calcification (CAC) using dual-source computed tomography (DSCT).

MATERIALS AND METHODS

We retrospectively analysed 77 consecutive patients who underwent calcium-scoring and angiographic cardiac DSCT. The long- and short-axis dimensions, axis areas of the aortic annulus, sinotubular junction and ascending aorta at the level of the pulmonary trunk in diastole and systole were measured. Average dimensions and relative areal changes between diastole and systole (%RA) of aortic annulus, sinotubular junction and ascending aorta were compared.

RESULTS

Systolic and diastolic long- and short-axis dimensions of the aortic annulus in patients with CAC (n = 44) demonstrated statistically significant differences (27.00 ± 2.84 mm vs. 28.04 ± 2.62 mm; P < 0.001; 21.78 ± 2.55 mm vs. 20.88 ± 2.31 mm; P < 0.001), while differences in average diameters and areas of the aortic annulus were nonsignificant (P > 0.586). Systolic and diastolic axial areas of the sinotubular junction in patients with CAC demonstrated significant differences (7.21 ± 1.80 cm(2) vs. 6.92 ± 1.75 cm(2); P < 0.001). The %RA of the ascending aorta in patients with severe CAC (CAC score >400; n = 15) was significantly reduced compared to patients with minimal-to-moderate CAC (CAC score <400; n = 29; 4.77 ± 2.88 vs. 7.51 ± 3.81, P = 0.014).

CONCLUSIONS

In comparison with patients without CAC, the long- and short-axis dimensions of the aortic annulus and areas of the sinotubular junction show significant differences during the cardiac cycle in patients with CAC. The presence of severe CAC significantly influences the flexibility of the wall of the ascending aorta.

The use of CorMatrix extracellular matrix for aortic root enlargement

This manuscript presents a published record of the use and efficacy of the extracellular matrix CorMatrix and why it may be superior to other materials used for aortic root enlargement. The potential benefits of an extracellular matrix are the natural ingrowth and development of native arterial cells and structure.

The anatomy of the aortic root

The aortic root is the anatomical bridge between the left ventricle and the ascending aorta. It is made up of the aortic valve leaflets, which are supported by the aortic sinuses (of Valsalva), and the interleaflet triangles interposed between the basal attachments of the leaflets. As such, it possesses significant length, and because of the semilunar attachment of the leaflets, there is no discrete proximal border to the root. It is limited distally, nonetheless, by the supravalvar ridge, or sinutubular junction. Descriptions of the aortic root over the years have been bedeviled by accounts of a valve anulus. There are at least two rings within the root, but neither serves to support the valve leaflets, each leaflets being attached in semilunar fashion from the sinutubular junction to a basal ventricular attachment Two leaflets are supported by muscle, and the third has an exclusively fibrous attachment. The root acts as a bridging structure not only anatomically, separating the myocardial and arterial components of the left ventricular pathway, but also functionally, since its proximal and distal components can withstand considerable changes in ventricular and arterial pressures. In this review, we describe the anatomy of this crucial cardiac component, emphasizing the current problems which have arisen due to indiscriminate descriptions of a nonexistent anulus.