The Ross operation - a feasible and safe option in the setting of a bicuspid aortic valve?

OBJECTIVES

The Ross operation in the setting of a bicuspid aortic valve (BAV) remains controversial. Using data from the German Ross Registry, we sought to investigate the effect of the presence of a BAV on autograft function and diameters over time after the Ross operation compared with the presence of a tricuspid aortic valve (TAV).

METHODS

A total of 1277 patients (mean age 42.2 + or - 15.3 years) with intra-operatively documented aortic valve morphology during the Ross operation were analysed in the present study (sub-coronary technique, n=648, root replacement technique, n=629 patients). A BAV was present in 70.9% of patients. Clinical and echocardiographic follow-up was performed preoperatively and at pre-specified intervals (mean follow-up 5.7 + or - 3.8 years, 6806 patient-years). Hierarchical multilevel modelling techniques were used for the statistical analysis of serial measurements and comparisons among groups.

RESULTS

Initial neo-aortic regurgitation was lower in the BAV group (0.52 vs 0.62 aortic insufficiency (AI) grades, p=0.008), whereas the annual increase of it did not differ among groups. In both surgical techniques, no significant development of neo-aortic regurgitation (<0.02 AI grades per year) could be detected. Initial aortic annulus and sinus dimensions did not differ in the presence of a BAV. However, BAV patients developed a higher degree of annulus and sinus dilatation over time (0.20mm per year vs 0.06 mm per year, p=0.003; 0.24 vs 0.11 mm per year, p=0.013). This effect persisted when allowing for the two different surgical techniques. Baseline sinotubular junction (STJ) diameters did not differ among groups and annual increase thereof was similar (29.15 mm vs 28.9 mm, p=0.69; 0.44 mm vs 0.35 mm, p=0.15).

CONCLUSIONS

For the observed time period, postoperative neo-aortic regurgitation after the Ross procedure did not differ between patients with a BAV or a TAV. Root dimensions, although clinically not relevant, increased in both valve entities supporting surgical reinforcement strategies. We cannot consider a BAV as a contraindication for the Ross operation.

Impact of valves in a biomechanical heart model assisting failing hearts

Experimental valveless muscular blood pumps (biomechanical hearts) in goats can pump more than 1 L.min(-1), but due to a high pendulum volume, no significant flow contribution to the circulation is gained. Thus valved and valveless biomechanical hearts were compared for efficacy. Heart failure was induced in 5 adult Bore goats by repeated intracoronary embolization. A valved and balloon-equipped pumping chamber was integrated into the descending aorta, simulating standard biomechanical circulatory support. The valveless biomechanical heart supported a failing heart with a baseline cardiac output of 2,670 +/- 710 mL.min(-1) by contributing additional flow of 113 +/- 37 mL.min(-1). The biomechanical heart model incorporating an outlet valve offered an additional 304 +/- 126 mL.min(-1), and the use of 2 valves significantly enhanced pulmonary blood flow by 1,235 +/- 526 mL.min(-1). The use of 2 valves in biomechanical hearts seems to be essential to achieve adequate circulatory support. Double-valved biomechanical hearts driven by an appropriate skeletal muscle ventricle may contribute to the therapy of heart failure.

Neoaortic root diameters and aortic regurgitation in children after the Ross operation

BACKGROUND

For children who require aortic valve replacement, the Ross operation provides a unique advantage of growth potential of the pulmonary autograft in the aortic position. This study assessed the progression of autograft root diameters and its effect on aortic regurgitation (AR).

METHODS

Neoaortic echo dimensions from 48 children (<16 years) undergoing Ross operation who had follow-up echocardiograms before age 20 were analyzed (mean follow-up, 5.1 +/- 3.3 years).

RESULTS

The mean age at the time of the Ross operation was 10.0 +/- 4.3 years. Mean z values of the neoaortic annulus (1.5 +/- 0.4), sinus (2.5 +/- 0.4), and sinotubular junction (2.6 +/- 0.9) when the autograft was implanted were significantly larger compared with normal values (p < 0.001, all). The mean z values significantly increased with follow-up at the level of the sinus (0.5 +/- 0.1/year, p < 0.001) and the sinotubular junction (0.7 +/- 0.2, p < 0.001), but not at the level of the annulus (0.1 +/- 0.1, p = 0.59). AR increased with follow-up time (0.07 +/- 0.02 grade/year, p < 0.001). AR increased with sinotubular junction diameter (p = 0.028), but there was not significant evidence of an association with annulus diameter (p = 0.25) or sinus diameter (p = 0.40).

CONCLUSIONS

Children undergoing Ross operation have larger neoaortic root dimensions than healthy children. Growth of the annulus matches somatic growth. The diameters of the sinus and the sinotubular junction increase significantly relative to somatic growth. The latter may explain the development of AR.

Pathway analysis of differentially expressed genes in patients with acute aortic dissection

Background

Acute aortic dissection (AAD) is a life-threatening condition with high mortality and a relatively unclarified pathophysiological mechanism. Although differentially expressed genes in AAD have been recognized, interactions between these genes remain poorly defined. This study was conducted to gain a better understanding of the molecular mechanisms underlying AAD and to support the future development of a clinical test for monitoring patients at high risk.

Materials and Methods

Aortic tissue was collected from 19 patients with AAD (mean age 61.7 ± 13.1 years), and from eight other patients (mean age 32.9 ± 12.2 years) who carried the mutated gene for Marfan syndrome (MS). Six patients (mean age 56.7 ± 12.3 years) served as the control group. The PIQOR^TM Immunology microarray with 1076 probes in quadruplicates was utilized; the differentially expressed genes were analysed in a MedScan search using Pathway Assist software. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and protein analysis were performed.

Results

Interactions of MS fibrillin-1 (FBN1) in the MedScan pathway analysis showed four genes, fibulin-1 (FBLN1), fibulin-2 (FBLN2), decorin (DCN) and microfibrillar associated protein 5 (MFAP5), which were differentially expressed in all tissue from AAD. The validation of these genes by qRT-PCR revealed a minimum of three-fold downregulation of FBLN1 (0.5 ± 0.4 vs. 6.1 ± 2.3 fold, p = 0.003) and of DCN (2.5 ± 1.0 vs. 8.5 ± 4.7 fold, p = 0.04) in AAD compared to MS and control samples.

Conclusions

Downregulation of fibrillin-1 (FBN1) may weaken extracellular components in the aorta and/or interfer with the transmission of cellular signals and eventually cause AAD. Additional research on these four identified genes can be a starting point to develop a diagnostic tool.