A measured approach to managing the aortic root in patients with bicuspid aortic valve disease

Multiscale structure and function of the aortic valve apparatus

Whereas studying the aortic valve in isolation has facilitated the development of life-saving procedures and technologies, the dynamic interplay of the aortic valve and its surrounding structures is vital to preserving their function across the wide range of conditions encountered in an active lifestyle. Our view is that these structures should be viewed as an integrated functional unit, here referred to as the aortic valve apparatus (AVA). The coupling of the aortic valve and root, left ventricular outflow tract, and blood circulation is crucial for AVA's functions: unidirectional flow out of the left ventricle, coronary perfusion, reservoir function, and support of left ventricular function. In this review, we explore the multiscale biological and physical phenomena that underlie the simultaneous fulfillment of these functions. A brief overview of the tools used to investigate the AVA, such as medical imaging modalities, experimental methods, and computational modeling, specifically fluid-structure interaction (FSI) simulations, is included. Some pathologies affecting the AVA are explored, and insights are provided on treatments and interventions that aim to maintain quality of life. The concepts explained in this article support the idea of AVA being an integrated functional unit and help identify unanswered research questions. Incorporating phenomena through the molecular, micro, meso, and whole tissue scales is crucial for understanding the sophisticated normal functions and diseases of the AVA.

Ascending thoracic aortic aneurysm size at presentation and growth by diameter

AIM

To investigate the hypothesis that lung cancer screening allows for earlier identification of ascending thoracic aortic aneurysms (aTAAs) and that growth rates for aTAAs are greatest at larger sizes.

MATERIALS AND METHODS

This single referral centre retrospective study manually gathered computed tomography (CT) data from 732 patients presenting from July 2002 to August 2022. Five hundred and seventeen patients with aTAA >39 mm were identified to compare presenting diameter by year of presentation. Four hundred and thirty-two patients had CT examinations >3 months apart, allowing for growth analysis. Patients were separated by initial examination date (before or after 12/31/2013) for presenting size comparison. Patients were then divided into five groups based on aTAA diameter for growth rate analysis.

RESULTS

At identification, patients had a median aTAA diameter of 44 mm (IQR 41-47 mm). Patients with aTAAs identified prior to December 2013 (n=129) had an average aTAA diameter 1.7 mm larger than those identified later (n=388; p=0.003). The growth analysis showed an average growth rate of 0.1 mm/year (p<0.001) across the entire cohort. Patients with an aTAA diameter of ≥55 mm (n=12) grew the fastest at 1.9 mm/year (p<0.001). In the <40 mm group (n=43), the aTAAs expanded at 0.2 mm/year, faster than the 0.1 mm/year of the slowest expanding 45-49 mm group (n=130; p=0.04).

CONCLUSION

aTAA size at discovery was larger before lung cancer screening guidelines took effect in December 2013. The largest aTAAs expanded fastest, but growth rates were slowest in the medium-sized 45-49 mm diameter group.

Aortic wall thickness in dilated ascending aorta: Comparison between tricuspid and bicuspid aortic valve

BACKGROUND

Bicuspid aortic valve (BAV) is frequently associated with dilatation of the thoracic aorta. Peculiar anatomical, histological and mechanical changes of the aortic wall in BAV aortopathy have been hypothesized to suggest an increased risk of acute aortic complications in patients with BAV.

AIM

In this study we tried to clarify any differences in the adaptability of the aortic wall to the mechanism of dilatation between patients with BAV and those with TAV.

METHODS

In total, 354 samples were taken from 71 patients undergoing elective aortic surgery and divided into two groups: BAV group (n=16; 101 samples); and TAV group (n=55; 253 samples). Aortic wall thickness was measured with a dedicated caliper. The relationship between aortic wall thickness and aortic dilatation and demographic variables was evaluated cumulatively and comparatively (BAV versus TAV). In patients with more than three samples available, intrapatient variability was also studied. Finally, potential risk factors for severely reduced aortic wall thickness were also assessed.

RESULTS

Analysis of preoperative characteristics revealed significant differences in patient age (54±16years for BAV and 66±11years for TAV; P=0.0011), with no differences in variables related to aortic dilatation (including phenotype). Cumulative aortic wall thickness was significantly thinner in the anterior than in the posterior wall. In the comparative analysis, aortic wall thickness was significantly thinner in patients with BAV in both the anterior and posterior regions. Furthermore, in patients with BAV, dilatation>51mm was a significant predictor of severely reduced aortic wall thickness.

CONCLUSIONS

In our experience, patients with BAV aortopathy reached the cut-off for the surgical indication at an early age. Careful monitoring in patients with BAV is mandatory when aortic dilatation has reached 51mm, as it is related to significant anatomical changes.

The genetic basis of thoracic aortic disease: The future of aneurysm classification?

The expansion in the repertoire of genes linked to thoracic aortic aneurysms (TAA) has revolutionised our understanding of the disease process. The clinical benefits of such progress are numerous, particularly helping our understanding of non-syndromic hereditary causes of TAA (HTAAD) and further refinement in the subclassification of disease. Furthermore, the understanding of aortic biomechanics and mechanical homeostasis has been significantly informed by the discovery of deleterious mutations and their effect on aortic phenotype. The drawbacks in genetic testing in TAA lie with the inability to translate genotype to accurate prognostication in the risk of thoracic aortic dissection (TAD), which is a life-threatening condition. Under current guidelines, there are no metrics by which those at risk for dissection with normal aortic diameters may undergo preventive surgery. Future research lies with more advanced genetic diagnosis of HTAAD and investigation of the diverse pathways involved in its pathophysiology, which will i) serve to improve our understanding of the underlying mechanisms, ii) improve guidelines for treatment and iii) prevent complications for HTAAD and sporadic aortopathies.

Mid-term follow-up of aortic valve replacement for bicuspid aortic valve

OBJECTIVE

The purpose of this study was to evaluate the mid-term outcome of aortic valve replacement for bicuspid aortic valve and tricuspid aortic valve and the related risk factors.

METHODS

From January 2014 to June 2019, 177 tricuspid aortic valve patients and 101 bicuspid aortic valve patients who underwent aortic valve replacement in our hospital were collected. 1:1 propensity score matching analysis was used to control the bias in patient selection. The perioperative and follow-up data between the two groups were compared. Independent risk factors which were associated with the continued dilatation of the ascending aorta were identified by univariate or multivariate logistic regression analysis.

RESULTS

After the matching procedure, 160 patients were included in the analysis (80 in each group). Baseline characteristics, intraoperative, and perioperative outcomes were similar between the two groups (all p > 0.05). Moreover, 67 patients in the tricuspid aortic valve group and 70 in the bicuspid aortic valve group completed the follow-up. The ascending aorta change, annual change rate, and the proportion of continuous dilation of ascending aorta in bicuspid aortic valve group were significantly higher than those in the tricuspid aortic valve group (p < 0.05). Multivariate logistic regression analysis showed that type 1 in bicuspid aortic valve (OR 5.173; 95% CI 1.772, 15.101; p = 0.003), aortic regurgitation (OR 3.673; 95% CI 1.133, 11.908; p = 0.030), and aortic valve stenosis with regurgitation (OR 6.489; 95% CI 1.726, 24.404; p = 0.006) were independent risk factors for the continued dilatation of the ascending aorta in all AV patients. Furthermore, the multivariate logistic regression analysis showed that type 1 in bicuspid aortic valve (OR 5.157; 95% CI 1.053, 25.272; p = 0.043), age ≥ 40 years (OR 6.956; 95% CI 1.228, 39.410; p = 0.028), and aortic regurgitation (OR 4.322; 95% CI 1.174, 15.911; p = 0.028) were independent risk factors for the continued dilatation of the ascending aorta in bicuspid aortic valve patients.

CONCLUSION

Compared with tricuspid aortic valve patients, the ascending aorta of bicuspid aortic valve patients is more likely to continue to enlarge after aortic valve replacement. Type 1 in bicuspid aortic valve, age ≥ 40 years, and aortic regurgitation were the independent risk factors.

Pathology of the Aorta and Aorta as Homograft

The aorta is not a rigid tube, it is an “organ” with lamellar units, consisting of elastic fibers, extracellular matrix and smooth muscle cells in between as parenchyma. Several diseases may occur in the natural history of the aorta, requiring replacement of both semilunar cusps and ascending aorta. They may be congenital defects, such as bicuspid aortic valve and isthmal coarctation with aortopathy; genetically determined, such as Marfan and William syndromes; degenerative diseases, such as atherosclerosis and medial necrosis with aortic dilatation, valve incompetence and dissecting aneurysm; inflammatory diseases such as Takayasu arteritis, syphilis, giant cell and IgM4 aortitis; neoplasms; and trauma. Aortic homografts from cadavers, including both the sinus portion with semilunar cusps and the tubular portion, are surgically employed to replace a native sick ascending aorta. However, the antigenicity of allograft cells, in the lamellar units and interstitial cells in the cusps, is maintained. Thus, an immune reaction may occur, limiting durability. After proper decellularization and 6 months’ implantation in sheep, endogenous cell repopulation was shown to occur in both the valve and aortic wall, including the endothelium, without evidence of inflammation and structural deterioration/calcification in the mid-term. The allograft was transformed into an autograft.

State-of-the art bicuspid aortic valve repair in 2020

Patients with a bicuspid aortic valve (BAV) frequently require surgical intervention for aortic regurgitation (AR) and/or aneurysm. Valve-preserving surgery and repair of regurgitant BAVs have evolved into an increasingly used alternative to replacement. Anatomic predictors of possible repair failures have been identified and solutions developed. Using current techniques most non-calcified BAVs can be preserved or repaired. Excellent repair durability and freedom from valve-related complications can be achieved if all pathologic components of aortic valve and root including annular dilatation are corrected. Anatomic variations must be addressed using tailored approaches.

Open hemiarch versus clamped ascending aorta replacement for aortopathy during initial bicuspid aortic valve replacement

BACKGROUND

There is controversy regarding the extent of aortic resection necessary in patients with aortopathy related to bicuspid aortic valve disease. To address this issue, we reviewed our experience in patients undergoing ascending aorta replacement during bicuspid aortic valve replacement.

METHODS

We reviewed 702 patients who underwent ascending aorta replacement at the time of initial nonemergent native bicuspid aortic valve replacement at our institution between January 2000 and June 2017. Treatment cohorts included an open hemiarch replacement group (n = 225; 32%) and a clamped ascending aorta replacement group (n = 477; 68%).

RESULTS

Median patient age was 60 years (interquartile range [IQR], 51-67 years), female sex was present in 113 patients 16%, ejection fraction was 62% (IQR, 56%-66%), and aortic arch diameter was 33 mm (IQR, 29-36 mm). Cardiopulmonary bypass time was longer in the hemiarch replacement group (188 minutes vs 97 minutes; P < .001). Procedure-related complications (36%) and mortality (<1%) were similar in the 2 groups; however, the hemiarch group had an increased odds of blood transfusion (odds ratio, 1.62; 95% confidence interval [CI], 1.15-2.28; P = .006). The median duration of follow-up was 6.0 years (95% CI, 5.3-6.8 years). Overall survival was 94 ± 1% at 5 years and 80 ± 2% at 10 years. Multivariable analysis demonstrated similar survival in the 2 groups (hazard ratio, 0.83; 95% CI, 0.51-1.33; P = .439). No repeat aortic arch operations were done for aortopathy over the duration of clinical follow-up.

CONCLUSIONS

Compared with patients in the clamped ascending aorta replacement group, patients in the hemi-arch replacement group had longer cardiopulmonary bypass and aortic cross-clamp times, along with an increased risk of blood transfusion, but similar freedom from repeat aortic arch operation and survival. We identified no advantage of performing hemiarch replacement in the absence of aortic arch dilation.

Collagen analysis of the ascending aortic dilatation associated with bicuspid aortic valve disease compared with tricuspid aortic valve

Dilatation of the ascending aorta is a common occurrence in patients with bicuspid aortic valve (BAV). The aim of the current study was to characterize collagen content in advanced glycation end products (AGEs) of dilated aortic tissue from two distinct areas, concave and convex aortic sites in patients with BAV and TAV. Collagen contents extracted from 100 mg tissue was isolated by enzymatic digestion using pepsin and the nondigested material was further digested using cyanogen bromide, insoluble collagen fraction (ICF) was extracted by hydrochloric acid hydrolysis. BAV tissue showed diminished fluorescence of the pepsin extracted fraction (PEF) compared with TAV tissue (12.4 ± 1.0% vs 32.9 ± 7.6%, p = 0.05). Patients with BAV had PEF of collagens significantly diminished in the dilated ascending aorta, especially in its convex portion, in course of aging and increment of dilated diameters. It is suggestible that BAV patients present more highly AGE-modified collagens in their ascending aorta.

Towards More Personalized Surgical Indications for Thoracic Aortic Dilatation: Are We There Yet?

Thoracic aortic aneurysms remain an important cause of death in the general population. The key to improving patient prognosis with thoracic aortic dilatation lies in early identification and tailored management strategies. Advances in the understanding of the molecular mechanisms of aneurysm formation, the natural history of disease, and clinical risk factors have led to significant improvements in patient management and overall outcomes. In the past decade, identification of the genetic basis of disease, together with wider availability of molecular testing, ushered in a new era for a tailored approach to the management of patients with thoracic aortic aneurysms. In this viewpoint, we explore these various iterative steps and future challenges.

New Insights Into Unicuspid Aortic Valve Disease in Adults: Not Just a Subtype of Bicuspid Aortic Valves

BACKGROUND

The clinical presentation, echocardiographic features, and patterns of aortic dilatation in unicuspid aortic valves (UAVs) are not well defined.

METHODS

From 2011 to 2015, all data from adult patients with confirmed UAVs (n = 42) who underwent aortic valve surgery were reviewed.

RESULTS

The mean age of the study population was 33.9 ± 1.7 years; 33 were male (78%). Mixed aortic valve disease (stenosis and regurgitation) was the most common mode of presentation (n = 25; 59%). Preoperative diagnosis of UAV was made in only 6 patients (14%). Preoperative transesophageal echocardiography in the operating room increased the diagnosis to 69% of the patients. The peak and mean aortic gradients were 80 ± 29 mm Hg and 50 ± 20 mm Hg, respectively. The aortic valve area was 1.1 ± 0.4 cm(2). Overall, 21% of patients (n = 9) had aortic dilatation (> 45 mm): 6 patients (14%) had isolated ascending aortic dilatation, 1 patient (2%) had isolated aortic root dilatation, and 2 patients (5%) had combined aortic root and ascending aortic dilatation. In contrast, 71% of patients (n = 30) had a dilated aortic annulus (> 25 mm). Mean aortic diameters measured using transesophageal echocardiography were: aortic annulus: 25.8 ± 3.4 mm; sinus of Valsalva: 32.1 ± 5 mm, sinotubular junction: 28.1 ± 5 mm, and ascending aorta: 36.2 ± 5 mm. The valve was repaired using a bicuspidization technique in 8 patients (19%) and replaced using a Ross procedure in 34 patients (81%).

CONCLUSIONS

UAVs remain significantly underdiagnosed in young adults with aortic valve disease. UAVs are associated with a distinct pattern of aortic dilatation, which is mainly present at the level of the aortic annulus. In a small proportion of patients, the valve can be surgically repaired.

Effect of statins on aortic root growth rate in patients with bicuspid aortic valve anatomy

Bicuspid aortic valve (BAV) anatomy is associated with increased growth rate of the aortic root compared to tricuspid aortic valves. Statins decrease the growth rate of abdominal aneurysms; however their effect on the aortic root growth rate has not been elucidated. The present study evaluated the association between use of statins and aortic root growth in patients with BAV. A total of 199 patients (43 ± 15 years, 69 % male) with BAV who underwent ≥2 echocardiographic measurements of the aortic root ≥1 year apart were included in this retrospective observational study. Median follow-up duration was 4.7 years (interquartile range 2.7–8.3 years). Growth rate (mm/year) of the aortic root was compared between statin users (n = 41) and non-users (n = 158). Statin users were significantly older and had more cardiovascular risk factors than their counterparts. Ascending aorta diameter was significantly smaller at baseline and at follow-up in statin users compared with non-users when adjusted for coronary artery disease, age and medication. The average annual growth rate was 0.08 mm/year (95 % confidence interval 0.03–0.13) for the aortoventricular junction, 0.16 mm/year (0.11–0.21) for the sinus of Valsalva, 0.12 mm/year (0.07–0.17) for the sinotubular junction and 0.45 mm/year (0.37–0.53) for the ascending aorta. The dilation rate of the aortic segments was not different between statin users and non-users. In conclusion, in patients with BAV, although the use of statins was associated with smaller ascending aorta, the annual dilation rate of the aortic root was not influenced by the use of statins.

Identification of fibrillin 1 gene mutations in patients with bicuspid aortic valve (BAV) without Marfan syndrome

Background

Bicuspid aortic valve (BAV) is the most frequent congenital heart disease with frequent involvement in thoracic aortic dilatation, aneurysm and dissection. Although BAV and Marfan syndrome (MFS) share some clinical features, and some MFS patients with BAV display mutations in FBN1, the gene encoding fibrillin-1, the genetic background of isolated BAV is poorly defined.

Methods

Ten consecutive BAV patients [8 men, age range 24–42 years] without MFS were clinically characterized. BAV phenotype and function, together with evaluation of aortic morphology, were comprehensively assessed by Doppler echocardiography. Direct sequencing of each FBN1 exon with flanking intron sequences was performed on eight patients.

Results

We detected three FBN1 mutations in two patients (aged 24 and 25 years) displaying aortic root aneurysm ≥50 mm and moderate aortic regurgitation. In particular, one patient had two mutations (p.Arg2726Trp and p.Arg636Gly) one of which has been previously associated with variable Marfanoid phenotypes. The other patient showed a pArg529Gln substitution reported to be associated with an incomplete MFS phenotype.

Conclusions

The present findings enlarge the clinical spectrum of isolated BAV to include patients with BAV without MFS who have involvement of FBN1 gene. These results underscore the importance of accurate phenotyping of BAV aortopathy and of clinical characterization of BAV patients, including investigation of systemic connective tissue manifestations and genetic testing.

The fate of the bicuspid valve aortopathy after aortic valve replacement

OBJECTIVES

The fate of the aortic dimensions in patients with a bicuspid aortic valve (BAV) after aortic valve replacement (AVR) is unclear. We investigated the evolution of aortic root and ascending aorta dimensions in patients with a BAV after AVR. To neutralize the effect of pathological transvalvular haemodynamics on aortic dimensions, we evaluated our hypotheses in patients with normal transvalvular haemodynamics after a subcoronary autograft procedure, which preserves intact the native aortic wall.

METHODS

We excluded patients operated on for endocarditis; who developed autograft insufficiency > trivial and who required autograft reoperation during the follow-up. We included 448 patients (361 with BAV; 340 males; 44.6 ± 11.4 years; mean follow-up: 7.5 ± 3.9 years). Valve phenotype was determined during surgery. Annual echocardiographic examinations (n = 3336) were performed (follow-up completeness: 98%). To allow for somatometric, gender and age influences, z-values of measurements were calculated from the general population (GP) and analysed using longitudinal methods.

RESULTS

The increase in ascending aorta did not differ from that expected in the GP (0.04 z-values/year; P = 0.06). No difference could be observed in diameter increase rates between BAV and tricuspid aortic valve patients (TAV) (0.04 vs 0.06 z-values/year; P = 0.3), as well as between BAV phenotypes. The sinus increase did not differ from that expected in the GP (0.03 z-values/year; P = 0.1), and no significant differences could be observed between BAV phenotypes. In patients undergoing aortoplasty (n = 70), no significant difference in the rates of ascending aorta and sinus increase could be observed, compared with the GP.

CONCLUSION

For the time period of this study and in patients with normal aortic root haemodynamics after AVR, ascending aorta dimensions over time are similar to that of the matched GP. Patients with a BAV did not exhibit higher rates of ascending aorta dilatation after AVR than patients with TAV. At least for the first postoperative decade, transvalvular haemodynamics appear to exhibit a greater influence than the genetic component of BAV on the development of the BAV aortopathy.

The living aortic valve: From molecules to function

The aortic valve lies in a unique hemodynamic environment, one characterized by a range of stresses (shear stress, bending forces, loading forces and strain) that vary in intensity and direction throughout the cardiac cycle. Yet, despite its changing environment, the aortic valve opens and closes over 100,000 times a day and, in the majority of human beings, will function normally over a lifespan of 70–90 years. Until relatively recently heart valves were considered passive structures that play no active role in the functioning of a valve, or in the maintenance of its integrity and durability. However, through clinical experience and basic research the aortic valve can now be characterized as a living, dynamic organ with the capacity to adapt to its complex mechanical and biomechanical environment through active and passive communication between its constituent parts. The clinical relevance of a living valve substitute in patients requiring aortic valve replacement has been confirmed. This highlights the importance of using tissue engineering to develop heart valve substitutes containing living cells which have the ability to assume the complex functioning of the native valve.

Towards an individualized approach to bicuspid aortopathy: different valve types have unique determinants of aortic dilatation

OBJECTIVES

Bicuspid aortic valve (BAV)-related aortopathy is increasingly recognized to be a heterogeneous disease entity, although the surgical approach, from indications to techniques, is still standard rather than individualized. We aimed to define the determinants of aortic dilatation in BAV patients stratified according to the valve morphotype.

METHODS

A consecutive echocardiographic series of 622 BAV patients was analysed. Among demographic (age, sex), anthropometric (height, weight, body surface area, body mass index), clinical (associated diseases) and echocardiographic variables (valve function, ventricular parameters), the determinants of aortic root and ascending tract diameter were assessed by multivariate regression models, as well as the predictors of aortic dilatation (size index >2.1 cm/m(2)) both in the overall population and separately in groups of different valve morphotypes (RL, right-left fusion; RN, right-non-coronary fusion).

RESULTS

Independent determinants of aortic root diameter (at sinuses) were age (P < 0.001), significant aortic regurgitation (P < 0.001), sex (female protective, P < 0.001) and valve morphotype (RN protective, P < 0.001). Independent determinants of ascending aortic diameter (tubular tract) were age (P < 0.001), RN morphotype (P < 0.001), body mass index (P = 0.005) and chronic obstructive pulmonary disease (P < 0.001). In univariate analysis, the RL morphotype was associated with dilatation (ASI > 2.1 cm/m(2)) at sinuses in 41% cases vs 22% for RN (P < 0.001), and the RN morphotype was associated with dilatation at the tubular tract in 68 vs 56% for RL (P = 0.007). The presence of root dilatation was predicted by age and absence of significant stenosis in the RL morphotype subgroup, and by severe regurgitation in the RN subgroup. In the RL-type subgroup, non-regurgitant aortic valve and chronic lung disease predicted dilatation at the ascending level; and in the RN-type subgroup, age and obesity.

CONCLUSIONS

The two most common BAV morphotypes are associated with aortic dilatation at two different tracts (RL at the root; RN at the tubular ascending tract) independently of valve function. Moreover, the determinants of aortic dilatation were at least in part different between the two morphotypes: this may provide stratification criteria for individualized methods of follow-up and treatment.

Aortopathies: etiologies, genetics, differential diagnosis, prognosis and management

Aortic root and ascending aortic dilatation are indicators associated with risk of aortic dissection, which varies according to underlying etiologic associations, indexed aortic root size, and rate of progression. Typical aortic involvement is most commonly seen in syndromic cases for which there is increasing evidence that aortic aneurysm represents a spectrum of familial inheritance associated with variable genetic penetrance and phenotypic expression. Aortic root and ascending aortic dimensions should be measured routinely with echocardiography. Pharmacologic therapy may reduce the rate of progression. Timing of surgical intervention is guided by indexed aortic size and rate of change of aortic root and ascending aorta dimensions. Lifelong surveillance is recommended.

Dilatation of the remaining aorta after aortic valve or aortic root replacement in patients with bicuspid aortic valve: a 5-year follow-up

BACKGROUND

The natural history and management of ascending aorta (AA) and arch dilatation in patients with bicuspid aortic valve (BAV) after aortic valve replacement (AVR) or aortic root replacement (ARR) remains controversial. Our aim is to identify dilatation of the remaining aorta after AVR or ARR in patients with BAV compared with patients with tricuspid aortic valve (TAV).

METHODS

Three hundred ninety-five patients who underwent AVR or ARR between 2002 and 2009 were studied. Preoperative computed tomography (CT) and echocardiography were performed in 192 patients with BAV, and the results were compared with those of 203 patients with TAV. An AA diameter 4.5 cm or greater was regarded as aneurysmal. Postoperative echocardiograms, computed tomographic scans, and magnetic resonance images were compared with subsequent imaging at a median follow-up of 4.6 years (2.2-9.8 years).

RESULT

Median ages of patients with BAV and patients with TAV were 57 ± 14 and 65 ± 16 years, respectively (p < 0.05). Preoperative diameter of AA in the BAV group with no aneurysm (3.5 cm; range, 3.0-4.0 cm; n = 143) was significantly higher than in the TAV group (3.3 cm; range, 3.1-3.8 cm; n = 129) (p < 0.001). In both BAV and TAV groups with nonaneurysmal aortas who underwent AVR, there was no significant expansion of the AA and arch at 5 years' follow-up. In patients with aneurysmal aorta (BAV group, n = 49; TAV group, n = 74) who underwent ARR, there was also no significant difference in growth of the remaining aorta at 3 and 5 years' follow-up.

CONCLUSIONS

No significant dilatation of the AA or arch was observed after AVR or ARR, respectively, in patients when a cut-off diameter of 4.5 cm or greater was considered for replacement in patients with BAV compared with patients with TAV up to 5 years after operation. The need for aortic replacement at smaller diameters was not found.

Side-specific endothelial-dependent regulation of aortic valve calcification: interplay of hemodynamics and nitric oxide signaling

Arterial endothelial cells maintain vascular homeostasis and vessel tone in part through the secretion of nitric oxide (NO). In this study, we determined how aortic valve endothelial cells (VEC) regulate aortic valve interstitial cell (VIC) phenotype and matrix calcification through NO. Using an anchored in vitro collagen hydrogel culture system, we demonstrate that three-dimensionally cultured porcine VIC do not calcify in osteogenic medium unless under mechanical stress. Co-culture with porcine VEC, however, significantly attenuated VIC calcification through inhibition of myofibroblastic activation, osteogenic differentiation, and calcium deposition. Incubation with the NO donor DETA-NO inhibited VIC osteogenic differentiation and matrix calcification, whereas incubation with the NO blocker l-NAME augmented calcification even in 3D VIC-VEC co-culture. Aortic VEC, but not VIC, expressed endothelial NO synthase (eNOS) in both porcine and human valves, which was reduced in osteogenic medium. eNOS expression was reduced in calcified human aortic valves in a side-specific manner. Porcine leaflets exposed to the soluble guanylyl cyclase inhibitor ODQ increased osteocalcin and α-smooth muscle actin expression. Finally, side-specific shear stress applied to porcine aortic valve leaflet endothelial surfaces increased cGMP production in VEC. Valve endothelial-derived NO is a natural inhibitor of the early phases of valve calcification and therefore may be an important regulator of valve homeostasis and pathology.

Are we ignoring the dilated thoracic aorta?

The pathophysiology of thoracic aortic aneurysm (TAA) formation involves a complex interplay of genetic predisposition, cardiovascular risk factors, and hemodynamic forces. The medical community has resorted to the use of pharmacologic agents based on weak data transplanted from either abdominal aortic aneurysms (AAAs) or Marfan syndrome. However, aneurysms differ significantly based on their anatomic location and etiology. Epidemiologic and experimental data demonstrate that different genetic and nongenetic risk factors as well as diverse physiologic processes are responsible for the development and progression of sporadic TAA, familial TAA, and AAA. Therefore, these disease processes need to be considered as distinct entities and not hastily grouped together. The extrapolation of data from one aneurysmal disease process to another is still ill-founded and potentially harmful. Clinical trials in TAA are required before medical therapies, such as β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, or macrolide antibiotics, can be recommended.

The influence of operative techniques on the outcomes of bicuspid aortic valve disease and aortic dilatation

BACKGROUND

Bicuspid aortic valve is associated with aortic aneurysm formation that may extend beyond the ascending aorta.

METHODS

Between 1979 and 1997, 143 bicuspid aortic valve patients had aortic valve operations with replacement of an aneurysmal ascending aorta: 93 (65%) underwent full root replacement and 50 (35%) underwent separate valve and graft replacement. Distal aortic anastomosis was open in 42 patients (29%) and closed in 101 (71%). Late survival and complications were compared by surgical technique.

RESULTS

Patients undergoing full root replacement tended to be younger (mean age 46 +/- 16 vs 59 +/- 13, p < 0.001) and presented with more aortic insufficiency (80% vs 35%, p < 0.001). Three (2.1%) hospital deaths occurred. Event-free survival was 82% (95% confidence interval, 75% to 88%) at 10 years and 41% (95% confidence interval, 11% to 71%) at 20 years. At a median follow-up of 11.5 years, the incidence of new aneurysms and late aortic complications were not significantly different among the procedure groups. Age at the time of operation was the only predictor of late survival (hazard ratio, 1.07; p = 0.007).

CONCLUSIONS

Aortic root replacement with distal aortic reconstruction can be achieved with very low operative mortality and excellent long-term outcomes in patients with bicuspid aortic valve and dilated ascending aorta. The type of surgical procedure done in the aortic root and in the distal ascending aorta does not influence late survival, subsequent operation, or aortic complications. This is likely influenced by our patient-specific strategy when replacing the aortic root and distal ascending aorta.

Repair, replacement, Ross: how I approach the older child with mixed aortic stenosis/aortic insufficiency

Most children with aortic valve disease present with isolated aortic regurgitation or stenosis, in which case valve repair is often possible, thus delaying or eliminating the need for valve replacement. In the child with mixed aortic stenosis and regurgitation, repair is often more complex and less successful, requiring replacement of the valve and/or root. Several elements require careful consideration in children including growth potential of the child, risk of future reoperations, and the need for anticoagulation. A formal decision tree in this context is difficult because of the high variability between patients and pathologies and the lack of prospective randomized data. Nevertheless, we here present our approach to the child with mixed aortic stenosis and regurgitation, exploring the various options and explaining our favored approach.