The Sinotubular Junction-to-Aortic Annulus Ratio as a Determinant of Supravalvar Aortic Stenosis Severity.

Supravalvar aortic stenosis (SVAS) severity guides management, including decisions for surgery. Physiologic and technical factors limit the determination of SVAS severity by Doppler echocardiography and cardiac catheterization in Williams syndrome (WS). We hypothesized SVAS severity could be determined by the sinotubular junction-to-aortic annulus ratio (STJ:An). We reviewed all preintervention echocardiograms in patients with WS with SVAS cared for at our center. We measured STJ, An, peak and mean Doppler gradients, and calculated STJ:An. We created 2 mean gradient prediction models. Model 1 used the simplified Bernoulli's equation, and model 2 used computational fluid dynamics (CFD). We compared STJ:An to Doppler-derived and CFD gradients. We reviewed catheterization gradients and the waveforms and analyzed gradient variability. We analyzed 168 echocardiograms in 54 children (58% male, median age at scan 1.2 years, interquartile range [IQR] 0.5 to 3.6, median echocardiograms 2, IQR 1 to 4). Median SVAS peak Doppler gradient was 24 mm Hg (IQR 14 to 46.5). Median SVAS mean Doppler gradient was 11 mm Hg (IQR 6 to 21). Median STJ:An was 0.76 (IQR 0.63 to 0.84). Model 1 underpredicted clinical gradients. Model 2 correlated well with STJ:An through all severity ranges and demonstrated increased pressure recovery distance with decreased STJ:An. The median potential variability in catheterization-derived gradients in a given patient was 14.5 mm Hg (IQR 7.5 to 19.3). SVAS severity in WS can be accurately assessed using STJ:An. CFD predicts clinical data well through all SVAS severity levels. STJ:An is independent of physiologic state and has fewer technical limitations than Doppler echocardiography and catheterization. STJ:An could augment traditional methods in guiding surgical management decisions.

Supravalvular Aortic Stenosis and the Risk of Premature Death Among Patients With Homozygous Familial Hypercholesterolemia.

Patients with homozygous familial hypercholesterolemia (HoFH) have a high risk for premature death. Supravalvular aortic stenosis (SVAS) is a common and the feature lesion of the aortic root in HoFH. The relation between SVAS and the risk of premature death in patients with HoFH has not been fully investigated. The present study analysis included 97 HoFH patients with mean age of 14.7 (years) from the Genetic and Imaging of Familial Hypercholesterolemia in Han Nationality Study. During the median (±SD) follow-up 4.0 (±4.0) years, 40 (41.2%) participants had SVAS and 17 (17.5%) participants experienced death. The proportion of premature death in the non-SVAS and SVAS group was 7.0% and 32.5%, respectively. Compared with the non-SVAS group, SVAS group cumulative survival was lower in the HoFH (log-rank test, p <0.001). This result was further confirmed in the multivariable Cox regression models. After adjusting for age, sex, low density lipoprotein cholesterol (LDL_C)-year-score, lipid-lowering drugs, cardiovascular disease, and carotid artery plaque, SVAS was an independent risk factor of premature death in HoFH on the multivariate analysis (hazard ratio 4.45; 95% confidence interval, 1.10 to 18.12; p = 0.037). In conclusion, a significantly increased risk of premature death was observed in HoFH patients with SVAS. Our study emphasized the importance of careful and aggressive management in these patients when appropriate.

Whole exome sequencing in patients with Williams-Beuren syndrome followed by disease modeling in mice points to four novel pathways that may modify stenosis risk.

Supravalvular aortic stenosis (SVAS) is a narrowing of the aorta caused by elastin (ELN) haploinsufficiency. SVAS severity varies among patients with Williams-Beuren syndrome (WBS), a rare disorder that removes one copy of ELN and 25-27 other genes. Twenty percent of children with WBS require one or more invasive and often risky procedures to correct the defect while 30% have no appreciable stenosis, despite sharing the same basic genetic lesion. There is no known medical therapy. Consequently, identifying genes that modify SVAS offers the potential for novel modifier-based therapeutics. To improve statistical power in our rare-disease cohort (N = 104 exomes), we utilized extreme-phenotype cohorting, functional variant filtration and pathway-based analysis. Gene set enrichment analysis of exome-wide association data identified increased adaptive immune system variant burden among genes associated with SVAS severity. Additional enrichment, using only potentially pathogenic variants known to differ in frequency between the extreme phenotype subsets, identified significant association of SVAS severity with not only immune pathway genes, but also genes involved with the extracellular matrix, G protein-coupled receptor signaling and lipid metabolism using both SKAT-O and RQTest. Complementary studies in Eln+/-; Rag1-/- mice, which lack a functional adaptive immune system, showed improvement in cardiovascular features of ELN insufficiency. Similarly, studies in mixed background Eln+/- mice confirmed that variations in genes that increase elastic fiber deposition also had positive impact on aortic caliber. By using tools to improve statistical power in combination with orthogonal analyses in mice, we detected four main pathways that contribute to SVAS risk.

Stenosis coexists with compromised α1-adrenergic contractions in the ascending aorta of a mouse model of Williams-Beuren syndrome.

Williams-Beuren syndrome (WBS) is a rare disorder caused by a heterozygous deletion of 26-28 contiguous genes that affects the brain and cardiovascular system. Here, we investigated whether WBS affects aortic structure and function in the complete deletion (CD) mouse model harbouring the most common deletion found in WBS patients. Thoracic aortas from 3-4 months-old male CD mice and wild-type littermates were mounted in wire myographs or were processed for histomorphometrical analysis. Nitric oxide synthase (NOS) isoforms and oxidative stress levels were assessed. Ascending aortas from young adult CD mice showed moderate (50%) luminal stenosis, whereas endothelial function and oxidative stress were comparable to wild-type. CD mice showed greater contractions to KCl. However, α1-adrenergic contractions to phenylephrine, but not with a thromboxane analogue, were compromised. Decreased phenylephrine responses were not affected by selective inducible NOS blockade with 1400 W, but were prevented by the non-selective NOS inhibitor L-NAME and the selective neuronal NOS inhibitor SMTC. Consistently, CD mice showed increased neuronal NOS expression in aortas. Overall, aortic stenosis in CD mice coexists with excessive nNOS-derived NO signaling that compromises ascending aorta α1-adrenergic contractions. We suggest that increased neuronal NOS signaling may act as a physiological 'brake' against the detrimental effects of stenosis.

Cardiovascular disease in Williams syndrome.

PURPOSE OF REVIEW: Williams syndrome is a multisystem disorder seen with some regularity at most pediatric centers and usually fairly often at larger centers. Cardiovascular abnormalities, because of elastin deficiency, are the leading cause of morbidity and mortality in patients with Williams syndrome. The present article presents a review of the most recent developments regarding the cardiovascular issues in Williams syndrome. RECENT FINDINGS: Cardiovascular abnormalities occur in 80% of patients with Williams syndrome, the majority of which are arterial stenoses. The stenoses seen in Williams syndrome now appear to arise from deficient circumferential arterial growth. Pharmacological therapies aimed at improving the vascular stenoses have shown some promise in animal models. Surgical outcomes for supravalvar aortic stenosis are good at most centers. Transcatheter interventions are largely ineffective in Williams syndrome. Multilevel surgical pulmonary artery reconstruction has excellent results for peripheral pulmonary artery stenosis. Periprocedural risk stratification and management algorithms may decrease the risk of cardiovascular complications. SUMMARY: Cardiovascular abnormalities are a major determining factor in the clinical picture and trajectory of patients with Williams syndrome. Advances in surgical techniques, medical therapeutic options, and periprocedural management hold promise for significant improvements in the cardiovascular outcomes of these patients.

Fatal severe coronary artery stenosis in Williams syndrome: decision making using late gadolinium enhancement cardiovascular MRI.

Williams syndrome is a well-recognised congenital disorder characterised by cardiovascular, connective tissue, and central nervous system abnormalities. Coronary artery abnormalities are seen in patients with supravalvar aortic stenosis, but end-stage ischaemic heart disease is rare. We report a case of end-stage ischaemic heart disease due to severe coronary arterial stenosis, highlighting how cardiovascular MRI contributed to the management.

Novel ELN mutation in a family with supravalvular aortic stenosis and intracranial aneurysm.

Pathogenic germline mutations in ELN can be detected in patients with supravalvular aortic stenosis. The mutation might occur de novo or be inherited following an autosomal dominant pattern of inheritance. In this report we describe a three-generation family suffering from supravalvular aortic stenosis, various other arterial stenoses, sudden death, and intracranial aneurysms. A frameshift mutation in exon 12, not described before, was detected in the affected family members. This report emphasises the importance of family history, genetic counselling, and demonstrates the great variability in the phenotype within a single SVAS family.

Elastins from patients with Williams-Beuren syndrome and healthy individuals differ on the molecular level.

Williams-Beuren syndrome (WBS) is a congenital disorder, which involves the heterozygous deletion of the elastin gene and other genes on chromosome 7. Clinical symptoms that are associated with hemizygosity of the essential extracellular matrix protein elastin include premature aging of the skin and supravalvular aortic stenosis. However, only little is known about the molecular basis of structural abnormalities in the connective tissue of WBS patients. Therefore, for the first time this study aimed to systematically characterize and compare the structure and amount of elastin present in skin and aortic tissue from WBS patients and healthy individuals. Elastin fibers were isolated from tissue biopsies, and it was found that skin of WBS patients contains significantly less elastin compared to skin of healthy individuals. Scanning electron microscopy and mass spectrometric measurements combined with bioinformatics data analysis were used to investigate the molecular-level structure of elastin. Scanning electron microscopy revealed clear differences between WBS and healthy elastin. With respect to the molecular-level structure, it was found that the proline hydroxylation degree differed between WBS and healthy elastin, while the tropoelastin isoform appeared to be the same. In terms of cross-linking, no differences in the content of the tetrafunctional cross-links desmosine and isodesmosine were found between WBS and healthy elastin. However, principal component analysis revealed differences between enzymatic digests of elastin from healthy probands and WBS patients, which indicates differing susceptibility toward enzymatic cleavage. Overall, the study contributes to a better understanding of the correlation between genotypic and elastin-related phenotypic features of WBS patients. © 2016 Wiley Periodicals, Inc.

Systolic flow displacement using 3D magnetic resonance imaging in an experimental model of ascending aorta aneurysm: impact of rheological factors.

OBJECTIVES: The impact of systolic flow displacement on the development and progression of ascending aorta dilatation in aortic valve disease is a matter of controversy. Our objective was to study the association between rheological stimuli and development of aortic dilatation in a large animal model of supravalvular aortic stenosis and eccentric flow. METHODS: Twenty-four pigs weighing 10-14 kg were randomly allocated (ratio 2:1) to either restrictive ascending aortic banding or sham operation. Aortic diameter and systolic flow displacement were assessed by three-dimensional phase-contrast magnetic resonance imaging at 6 and 18 weeks after surgery. Twenty pigs (n = 14, banded vs n = 6, sham) completed full imaging protocol and were included in the analysis. After the last follow-up, a subset of 14 animals was sacrificed for histological analysis. RESULTS: All banded animals developed significant progressive aortic dilatation both at 6 and 18 weeks, compared with sham-operated pigs: 34.3 ± 4.8 vs 21.4 ± 2.7 mm at 6 weeks (P < 0.001); and 50.0 ± 8.4 vs 38.0 ± 8.3 mm at 18 weeks (P = 0.002). The peak gradient at 6 weeks showed a trend to positively correlate with aortic diameter at 18 weeks (R = 0.50, P = 0.06), whereas the systolic flow displacement at 6 weeks correlated better with aortic diameter at 18 weeks (R = 0.59, P = 0.02). The aortic wall thickness was significantly decreased in the anterior aortic section in banded, compared with sham-operated, pigs (1.5 ± 0.4 vs 2.0 ± 0.1 mm, respectively; P = 0.03). In addition, banded pigs showed a higher degree of cystic medial necrosis and elastin fibre fragmentation, compared with sham-operated animals. CONCLUSIONS: In this preclinical model of supravalvular aortic stenosis and eccentric flow, we found that systolic flow displacement at earlier stages is positively correlated with the degree of aortic dilatation during follow-up as assessed by three-dimensional phase-contrast magnetic resonance imaging. If our findings are confirmed in further studies, this imaging parameter might be useful to identify those subjects with aortic valve disease who are at risk of developing aortic dilatation at a later stage.

An unusual complication of three-patch repair of supravalvar aortic stenosis.

Three-patch repair of supravalvar aortic stenosis is a widely accepted surgical approach for this congenital heart lesion. We describe an unusual complication of this approach, which resulted in ischemia in the left anterior coronary artery distribution. Subtle oversizing of the left sinus of Valsalva patch led to kinking of the origin of the left anterior descending artery; the circumflex artery was not affected. Sinus of Valsalva reconstruction and reimplantation of the left coronary button restored normal coronary perfusion.

Comparison of electrocardiographic QTc duration in patients with supravalvar aortic stenosis with versus without Williams syndrome.

Cardiovascular abnormalities in Williams syndrome (WS) are largely attributable to elastin haploinsufficiency resulting from a large deletion of the elastin-containing region on chromosome 7q11.23. The risk of sudden death in patients with WS is 25- to 100-fold greater than that in the general population. The corrected QT (QTc) interval is prolonged in 14% of patients with WS. Patients with nonsyndromic supravalvar aortic stenosis (NSVAS) have elastin mutations resulting in elastin haploinsufficiency and a vascular phenotype nearly identical to that of WS. No previous studies have evaluated the QTc duration in NSVAS. A retrospective review of all electrocardiograms (ECGs) performed on consecutive patients with NSVAS at Arkansas Children's Hospital from January 1, 1985 to January 1, 2012 was completed. ECGs with nonsinus rhythm or unmeasurable intervals were excluded. The ECGs were read by 1 reader who was unaware of previous readings. A QTc interval of ≥460 ms was defined as prolonged. The NSVAS cohort was compared to previously published WS and control groups using the mixed model for continuous electrocardiographic variables and the generalized estimating equation for binary indicators for prolonged QTc. The generalized estimating equation used bootstrapping with 1,000 replicates. A total of 300 ECGs (median 6, range 1 to 27) from the 35 identified patients with NSVAS met the inclusion criteria. A total of 482 ECGs from patients with WS and 1,522 ECGs from controls were included. The mean age of the patients with NSVAS at ECG was 7.3 ± 6.9 years; 64% were male. The mean QTc duration was 409 ± 20 ms in the NSVAS group, 418 ± 17 ms in the control group (p <0.001), and 436 ± 27 ms in the WS group (p <0.001 compared to the control group). The prevalence of QTc prolongation was 0.3% in the NSVAS group, 2.0% in the control group (p <0.001), and 14.8% in the WS group (p <0.001 compared to controls). No patients with NSVAS died. In conclusion, cardiac repolarization is normal in patients with NSVAS. Elastin haploinsufficiency does not appear to be the etiology of QTc prolongation in patients with WS. The possible contribution of other genes on 7q11.23 to QTc prolongation in WS should be investigated.

Analysis of coronary flow haemodynamics in homozygous familial hypercholesterolaemic adolescents with aortic supravalvular stenosis.

OBJECTIVE: To study coronary artery haemodynamics in adolescents with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis. METHODS: Patients diagnosed with familial hypercholesterolaemia who were younger than 16 years and who had undergone transthoracic echocardiography from 2007 to 2010 were included in this study. We included patients with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis and those with heterozygous familial hypercholesterolaemia. All patients underwent stress echocardiography, and left anterior descending coronary artery flow was successfully detected. Coronary flow velocity reserve was calculated as the ratio of hyperaemic mean diastolic flow velocity after injection of adenosine to basal mean diastolic flow velocity. Changes in coronary haemodynamics and the relationship between lipid concentrations were determined. RESULTS: A total of 11 patients with homozygous familial hypercholesterolaemia were enrolled in this study. Lipid concentrations were measured, and the mean coronary flow velocity reserve was 1.97 plus or minus 0.51. Seven children were included in the group of patients with heterozygous familial hypercholesterolaemia. In these children, the mean coronary flow velocity reserve was 3.08 plus or minus 0.84. CONCLUSION: The coronary flow velocity reserve of homozygous familial hypercholesterolaemic patients is lower than that of heterozygous familial hypercholesterolaemic patients, and it is associated with a high concentration of low-density lipoprotein cholesterol. Aortic stenosis and plaques compromised the ostia of the coronary artery and caused increased basal mean diastolic coronary velocity with blunted increase in peak velocity, which decreased the coronary flow velocity reserve.

Dynamic geometry of the left ventricular outflow tract of pigs with induced supravalvular aortic stenosis.

OBJECTIVES: Detailed information about the dynamic geometry of the left ventricular outflow tract (LVOT) is of great importance for transcatheter aortic valve implantation (TAVI), since these valves utilize the LVOT as a landing zone for optimum placement and fixation. The LVOT is generally considered circular in shape and stable in its conformation. However, recent studies indicate that this may not be the case. METHODS: Twenty-two 5-kg pigs (± 0.47 kg) were randomly allocated to either aortic banding (n = 14) or sham operation (n = 8). LVOT dynamic geometry was assessed using cardiovascular-magnetic resonance imaging, 9 weeks after banding of the ascending aorta. RESULTS: All the banded animals developed significant left ventricular hypertrophy (P = 0.01) compared with controls. All the animals demonstrated significant reduction in eccentricity index (P(intervention) < 0.01, P(control) < 0.05) and longest internal diameter (P(intervention) < 0.01, P(control) = 0.02) when comparing measurements from end-diastole to end-systole. No significant systolic or diastolic differences were found between the two groups. CONCLUSIONS: The main findings were: the LVOT (i) undergoes substantial geometric alterations throughout the cardiac cycle and (ii) is ellipsoid throughout the cardiac cycle, (iii) geometric changes during the cardiac cycle stems from compression of the long-axis of the LVOT and (iv) dynamic geometry did not change significantly after induction of significant LV hypertrophy. Thus, our data suggest that assumptions made in daily practice, of a circular and stable LVOT geometry, need to be revised.

Discrete contributions of elastic fiber components to arterial development and mechanical compliance.

OBJECTIVE: Even though elastin and fibrillin-1 are the major structural components of elastic fibers, mutations in elastin and fibrillin-1 lead to narrowing of large arteries in supravalvular aortic stenosis and dilation of the ascending aorta in Marfan syndrome, respectively. A genetic approach was therefore used here to distinguish the differential contributions of elastin and fibrillin-1 to arterial development and compliance. METHODS AND RESULTS: Key parameters of cardiovascular function were compared among adult mice haploinsufficient for elastin (Eln(+/-)), fibrillin-1 (Fbn1(+/-)), or both proteins (dHet). Physiological and morphological comparisons correlate elastin haploinsufficiency with increased blood pressure and vessel length and tortuosity in dHet mice, and fibrillin-1 haploinsufficiency with increased aortic diameter in the same mutant animals. Mechanical tests confirm that elastin and fibrillin-1 impart elastic recoil and tensile strength to the aortic wall, respectively. Additional ex vivo analyses demonstrate additive and overlapping contributions of elastin and fibrillin-1 to the material properties of vascular tissues. Lastly, light and electron microscopy evidence implicates fibrillin-1 in the hypertension-promoted remodeling of the elastin-deficient aorta. CONCLUSIONS: These results demonstrate that elastin and fibrillin-1 have both differential and complementary roles in arterial wall formation and function, and advance our knowledge of the structural determinants of vascular physiology and disease.

Surgical repair of supravalvular aortic stenosis with use of Brom's technique: short-term results in 9 children.

There are few published reports of the results of supravalvular aortic stenosis correction with the use of Brom's 3-patch technique. Herein, we report our use of this procedure and the short-term results therefrom.From 2002 through 2007, 9 children underwent surgical correction of localized supravalvular aortic stenosis at our hospital. The patients ranged in age from 5 to 14 years, and 8 had Williams syndrome. All operations were performed by the same surgical team.No clinically significant associated cardiac anomalies were encountered. Each aortic repair involved the use of pericardium, Dacron, or both. One patient had an uncorrected right coronary artery obstruction and died postoperatively of refractory supraventricular tachycardia. In all 8 patients who survived, postoperative transaortic blood pressure gradients were improved (range, 0-16 mmHg), and no repeat operations were needed after 6 to 55 months' follow-up.We consider Brom's technique to be safe in the repair of supravalvular aortic stenosis. In our limited series, it produced effective anatomic restoration, with good short-term and potentially good long-term results.

Predictors of survival after aortic valve replacement in patients with low-flow and high-gradient aortic stenosis.

AIMS: To identify predictors of survival following aortic valve replacement (AVR) in patients with low-flow and high-gradient aortic stenosis (AS). METHODS AND RESULTS: Eighty-six patients (aged 71 +/- 10 years) with severe AS [aortic valve mean pressure gradient >40 mmHg or valve area <1.0 cm(2)] and left ventricular (LV) dysfunction [ejection fraction (EF) <50%] underwent AVR. Cox proportional hazards were used to identify independent clinical and echocardiographic predictors of mortality. Operative (30-day) mortality was 10%. Peri-operative mortality was associated with lower mean LVEF, higher mitral E:A ratio, peak systolic pulmonary artery pressure (PSPAP), and serum creatinine (by 12%, 2.3, 28 mmHg, and 74 mmol/L, respectively, all P < 0.001), NYHA class III-IV (100 vs. 65%), concomitant CABG (89 vs. 55%), urgent surgery (78 vs. 35%), and longer bypass-time (by 28 min, all P < 0.05). Mortality at 4 years was 17%. Univariate predictors [hazard ratio (HR)] of 4-year mortality were: lower EF (HR 0.68 per % increase, P < 0.001), presence of restrictive LV filling (HR: 3.52, P < 0.001), raised PSPAP (HR: 1.07, P < 0.001), and CABG (HR: 4.93, P = 0.037). However, only low EF (<40%, HR 0.74, P = 0.030), the presence of restrictive filling (HR 1.77, P = 0.033), and raised PSPAP (>45 mmHg, HR 2.71, P = 0.010) remained as independent predictors after multivariate analysis. CONCLUSION: The severity of pre-operative systolic and diastolic LV dysfunction is the major predictor of mortality following AVR for low-flow and high-gradient AS.