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Evidence in favor of linkage to human chromosomal regions 18q, 5q and 13q for bicuspid aortic valve and associated cardiovascular malformations.

The aim of this study was to identify regions of the genome that harbor genes influencing inheritance of bicuspid aortic valve (BAV) and/or associated cardiovascular malformation (CVM). Aortic valve disease is an important clinical problem, which often results in valve replacement, the second most common cardiac surgery in the United States. In every age group, a majority of cases of valve disease involves a BAV. BAV is the most common CVM with a reported prevalence of 1-2%. Heritability studies indicate that BAV determination is almost entirely genetic. We used a family-based genome-wide linkage analysis with microsatellite markers. Parametric and nonparametric analyses were performed with the software GENEHUNTER and SOLAR (Sequential Oligogenic Linkage Analysis Routines). Thirty-eight families (353 subjects) with BAV and/or associated CVM were assessed. Each participant underwent a standardized echocardiographic examination. The highest LOD score, 3.8, occurred on chromosome 18q between markers D18S68 and D18S1161. Two other chromosomal regions, 5q15-21 (between D5S644 and D5S2027) and 13q33-qter (between D13S1265 and 13qter), exhibited suggestive evidence of linkage (LOD > 2.0). Further, two previously reported linkage peaks on 9q34 and 17q24 were replicated in family specific analyses. No significant X chromosome linkage peaks were identified. In this genome-wide scan we demonstrate for the first time, that BAV and/or associated CVM exhibit linkage to chromosomes 18q, 5q and 13q. These regions likely contain genes whose mutation results in BAV and/or associated CVM indicating their important role in valvulogenesis and cardiac development.

Aortic Valve↗

Approach to the patient with bicuspid aortic valve and ascending aorta aneurysm.

Bicuspid aortic valve (BAV) disease is a common congenital heart valve abnormality accounting for a large number of valve replacements in the United States. Although still incompletely understood, the natural history of BAV disease is severe aortic stenosis and associated ascending aortic dilatation. In addition to the increased risk of endocarditis, aortic dissection and severe aortic valve dysfunction are responsible for most fatal complications. Thus, early and precise recognition of this condition is mandatory. The new American College of Cardiology/American Heart Association recommendations highlight the role of MRI and CT as complimentary tools to echocardiography for the diagnosis and surveillance of the morphology of the aortic valve and ascending aorta. Moreover, better understanding of the cellular mechanisms, including inflammation, bone formation, atherosclerotic-like processes, and aortic wall abnormalities, as well as the heritability and genetic predisposition for the disease, will define the potential for targeted medical therapies in the future. Currently, the treatment of this condition is primarily surgical. Although combined valve and ascending aorta replacement has been the most common surgical approach in the past, the increased cumulative risk of thrombotic and embolic events among these young patients has led to more conservative approaches. Several valve-sparing approaches with comparable mid-term results compared with the classic procedures have recently been reported. However, longer follow-up studies will be helpful to better define the advantages of these new surgical options. After a quick overview of the natural history of the BAV, this article provides an updated approximation of the current knowledge of the pathophysiology as well as the recommendations for the management and treatment of this disease.

Journal Article↗

Congenital aortic stenosis secondary to dysplasia of congenital bicuspid aortic valves without commissural fusion.

The hearts of nine children with clinical evidence of congenital valve stenosis and a congenital bicuspid aortic valve were reviewed. Aortic stenosis was diagnosed on the basis of cardiac catheterization data in four patients, operative findings in two and auscultatory findings in three. The patients were 1 month to 9 years old; six were male and three female. In each patient the two commissures of the valve were free to the aortic wall. The cusps were thickened, rolled and redundant; microscopic studies revealed that they consisted of immature loose connective tissue consistent with a dysplastic or incompletely differentiated valve. The valve orifice was obstructed by the dysplastic cusps, and dysplastic changes rather than the commissural fusion were responsible for the observed aortic stenosis. These valves do not appear amenable to valvotomy because obstruction is due to the abnormal valve tissue. These findings may explain the occasional poor results of valvotomy in infants and children with congenital aortic valve stenosis.

Aortic Valve↗

Infective endocarditis of a bicuspid aortic valve caused by Hansenula anomala.

Infective endocarditis due to Hansenula anomala developed on a bicuspid aortic valve in a 40-year-old man. H. anomala, an ascomycetous yeast, may be a member of the normal flora of the throat and alimentary tract in humans but has not been previously known to be pathogenic in humans. A past history of intravenous drug use may have contributed to the development of disease in this patient.

Adult↗

Allograft aortic valve replacement for bicuspid aortic valves with 180-degree coronary ostia.

Congenital bicuspid aortic stenosis is often an indication for aortic valve replacement in young adults and children. However, when the coronary ostia are exactly 180 degrees opposite each other, placing a trileaflet human allograft with freehand technique can be difficult. The described technique enlarges the left ventricular outflow tract beginning at the annulus level, using only allograft tissue. In addition to allowing placement of a larger allograft, this method rotates the coronary ostia toward each other, converting the aortic root to three-sinus anatomy.

Aortic Valve↗

Presynaptic modulation of the release of noradrenaline from electrically stimulated bicuspid valve leaflet of the rabbit heart.

The bicuspid (mitral) valves were obtained from male albino New Zealand rabbits. The noradrenaline (NA) content (12.93 +/- 1.14 nmol/g) of the valve tissue was determined by high pressure liquid chromatography (HPLC) combined with electrochemical detection. After incubation with tritiated NA for 45 min, the tissues were mounted in perfusion baths and superfused with Krebs solution at a constant perfusion rate. After a 90 min washing period, the tissues were stimulated three times (S1; S2; S3) at a frequency of 1 or 10 Hz, and the release of NA was expressed as the stimulus-induced overflow of radioactivity. Using a constant number of impulses, the release of NA was significantly higher when the frequency applied was 10 Hz than in the case of 1 Hz. The release of NA was inhibited by stimulating the presynaptic alpha 2-adrenoceptors with xylazine or by stimulating the presynaptic muscarinic receptors with oxotremorine. Yohimbine (1 microM) not only overcame the effect of the alpha 2-adrenoceptor stimulation caused by xylazine, but increased it over the control level, whereas atropine blocked the inhibitory effect of oxotremorine. It is concluded that the adrenergic nerves in the valve tissue release NA in a frequency-dependent fashion, and the release of NA can be modulated through presynaptic alpha 2- and muscarinic receptors. This is the first case that neurochemical evidence was obtained showing that NA is released from the mitral valve and is subject to presynaptic modulation.

Animals↗

Dilatation of the aorta in pure, severe, bicuspid aortic valve stenosis.

BACKGROUND: Aortic complications are more frequent after bicuspid aortic valve (BAV) replacement (AVR), than tricuspid aortic valve replacement. We studied the size of the proximal thoracic aorta in patients with BAV undergoing AVR for pure, severe aortic stenosis, looking for dilatation in comparison with patients with a matched tricuspid aortic valve (TAV) and normograms of aortic size. METHODS: Aortic root and ascending aortic diameter measurements were taken at 3 levels, from electrocardiographic-gated multidetector row computed tomograms, in 28 patients with pure, severe aortic stenosis before AVR. The patients were divided in 2 groups (BAV, n = 10; TAV, n = 18). Patients with greater than mild aortic regurgitation or who were scheduled for aortic root replacement were excluded. RESULTS: Although patients in the BAV group were younger (P <.0001) and less likely to have hypertension (P <.005), their aortic diameters were larger than those of patients in the TAV group at all levels measured (aortic sinus, 41.1 +/- 8.1 mm vs 33.8 +/- 3.3 mm; sino-tubular junction, 39.0 +/- 7.8 mm vs 31.1 +/- 3.8 mm; right pulmonary artery level, 42.8 +/- 7.1 mm vs 33.7 +/- 4.3 mm; P <.005 for all). Whereas 60% (6/10) of patients in the BAV group had >/=1 aortic diameter measurements greater than the 95th age-adjusted percentile, 0% (0/18) of patients in the TAV group did. CONCLUSIONS: Patients with BAV undergoing AVR with pure, severe aortic stenosis commonly have moderate dilatation of the thoracic aorta, whereas matched patients with a TAV do not. This finding may contribute to the increased frequency of aortic complications seen in follow up of patients with a BAV after AVR.

Aged↗

The prevalence of bicuspid aortic valve in newborns by echocardiographic screening.

BACKGROUND: This study was carried out to determine the true prevalence of bicuspid aortic valve (BAV) in newborns, which has not yet been determined. METHODS: One thousand seventy five live born neonates (567 male neonates, 508 female neonates; gestational ages ranging from 27 to 42 weeks, and birth weights ranging from 720 to 4,780 g) were screened by transthoracic 2-dimensional echocardiography to assess the prevalence of BAV. RESULTS AND CONCLUSION: BAV was identified in a prevalence of 4.6 in 1,000 live births. The prevalence of BAV by sex was 7.1 of 1,000 in male neonates, and 1.9 of 1,000 in female neonates. All newborns with BAV were asymptomatic. Mild aortic regurgitation was found in only 1 neonate with BAV. Because BAV may result in aortic valvular stenosis and/or regurgitation, a recommendation of regular follow-ups and antibiotic prophylaxis for infective endocarditis should be necessary.

Aortic Valve↗

Weights of operatively-excised stenotic unicuspid, bicuspid, and tricuspid aortic valves and their relation to age, sex, body mass index, and presence or absence of concomitant coronary artery bypass grafting.

This study was designed to evaluate weights of operatively-excised stenotic aortic valves and to compare them with age, sex, body mass index, and presence or absence of concomitant coronary artery bypass grafting. Weights of operatively-excised stenotic aortic valves have not been previously reported. We weighed operatively-excised stenotic valves in 499 patients (aged 19 to 91 years, mean 70), none of whom had mitral valve replacement. The 499 aortic valves ranged in weight from 0.45 to 11.30 g (mean 2.67). The mean weights of the unicuspid and bicuspid valves were heavier than those of the tricuspid valves (4.36 vs 3.34 vs 2.04 g, p <0.05). Mean valve weights were greater in the 304 men than in the 195 women (3.19 vs 1.87 g, p <0.001), in the younger patients than in the older patients (3.13 g in patients 30 kg/m(2) (2.62 vs 2.76 vs 2.57 g). Weights of operatively-excised stenotic aortic valves provide objective evidence of valvular stenosis.

Adult↗

Weights of individual cusps in operatively-excised congenitally bicuspid stenotic aortic valves.

We weighed each cusp separately in 200 operatively excised stenotic congenitally bicuspid aortic valves. It was found in 152 patients (76%) that the cusps differed (by > 0.2 g) in weight and in 48 patients (24%) that the cusps were of similar (a < or = 0.2 g difference) weights. In 161 of the 200 patients (80%), raphes were present in 1 cusp; the raphe and nonraphe cusps differed in weight in 120 patients (74%), with the raphe cusps being larger in 89 patients (74%), and were of similar weights in 41 patients (26%). Of the 39 patients with raphes in neither cusp, 32 cusps (82%) differed in weight and 7 (18%) were of similar weights. The weight of each cusp differed more as the total valve weights increased.

Adult↗

Frequency of aortic root dilation in children with a bicuspid aortic valve.

Bicuspid aortic valve (BAV) is associated with aortic root dilation and dissection in adults, but the age and conditions when dilation begins are unknown. Using echocardiographic data, we compared the aortic root dimensions and valve hemodynamics of 76 children with BAV with valves derived from 41 normal children. The children with BAV had significantly larger aortic roots (p <0.001) regardless of the presence of aortic stenosis or regurgitation.

Adolescent↗

Aortic dimensions in patients with bicuspid aortic valve without significant valve dysfunction.

The dimensions of the entire aorta at different anatomic levels were measured by transthoracic 2-dimensional echocardiography in 162 consecutive patients with isolated bicuspid aortic valves (BAVs) without significant aortic valve dysfunction. Aortic dilation involved the aortic root and the ascending aorta but was not present in the descending and abdominal aorta. A significant increase in the dimensions of the aortic arch was found in patients with BAVs aged >40 years. Ascending aortic diameter and the extension of aortic dilation were significantly correlated with age, but no correlation was found between aortic dimensions and aortic valve morphology.

Adolescent↗

Frequency of bicuspid aortic valve in young male conscripts by echocardiogram.

The database of echocardiographic examinations performed during the military screening of 20,946 young men in northeastern Italy was systematically reviewed to assess the frequency, hemodynamic characteristics, and aortic sizes of subjects with bicuspid aortic valves (BAVs). One hundred sixty-seven patients with BAVs were identified (0.8%), of whom 80 (48%) were diagnosed de novo during military screening. Aortic insufficiency was the predominant hemodynamic lesion in 110 subjects (66%), mild in 90, and moderate to severe in 20. Patients with BAVs displayed larger aortic sizes than controls at each aortic level, and the degree of dilation was related to the presence but not the severity of aortic insufficiency.

Adolescent↗

Progression rate of ascending aortic dilation in patients with normally functioning bicuspid and tricuspid aortic valves.

Dilation of the ascending aorta (AA), which is disproportionate to associated valvular lesions, is a relatively well-recognized phenomenon in patients with a bicuspid aortic valve (BAV). The aim of this study was to evaluate the rate of changes in the AA dimensions and the outcome in patients with AA dilation and BAVs compared with patients with AA dilation and tricuspid aortic valves (TAVs). Serial transesophageal echocardiograms (>12 months apart) were performed in 113 consecutive patients (BAV, n=27 and TAV, n=86) with AA diameters of >or=40 and <or=60 mm, respectively, without associated significant aortic valve stenosis or regurgitation. Baseline diameters at the sinuses of Valsalva (SV), the sinotubular junction (STJ), and the tubular tract (TT) were similar in both groups (41.3+/-5.3 vs 42.3+/-6.3 mm, p=NS, 37.8+/-5.2 vs 38.7+/-5.5 mm, p=NS, and 47.3+/-5.3 vs 45.9+/-5.1, p=NS, respectively). During an average 3-year follow-up, the rate of AA diameter progression was similar for the BAV and TAV groups (0.86+/-0.81 vs 0.82+/-1.1 mm/year, p=NS for the SV; 1.06+/-1.6 vs 0.63+/-1.1 mm/year, p=NS for the STJ; and 0.81+/-1.1 vs 0.75+/-1.1 mm/year, p=NS for the TT, respectively). Three patients in the TAV group experienced cardiac death (2 died suddenly and 1 after emergency surgery for AA dissection); there was no occurrence of cardiac death in the BAV group. In conclusion, the rate of progression of AA aneurysms was similar in patients with BAVs and in those with TAVs. Furthermore, patients with BAVs did not have increased rates of AA related complications compared with patients with TAVs.

Aortic Aneurysm, Thoracic↗

Progression of aortic dilation in children with a functionally normal bicuspid aortic valve.

Adults with bicuspid aortic valves (BAVs) are at risk for progressive aortic dilation independent of valve function. The evolution of aortic dilation in children with functionally normal BAVs has not been studied. In this study, ascending aortic diameters were assessed in a group of children with functionally normal BAVs (peak gradient < or =16 mm Hg) to determine whether progressive dilation occurs during childhood. A cohort of 101 patients and 97 controls were studied with echocardiography. There were no differences in mean age (9.0 +/- 4.8 vs 8.7 +/- 6.1 years, p = 0.7) or body surface area (1.1 +/- 0.4 vs 1.1 +/- 0.5 m2, p = 0.9). Patients had significantly greater aortic dimensions than controls in all measured regions of the aorta, with the most striking discrepancy in the ascending aorta (2.3 +/- 0.6 vs 1.8 +/- 0.5 cm, p <0.0001). The size discrepancy was present from birth and persisted throughout childhood. Repeated measurements were performed in a subgroup of 28 patients and 25 controls. Patients had significantly greater increases in ascending aortic dimension than controls per year of follow-up (1.2 +/- 0.08 vs 0.6 +/- 0.08 mm/year, p <0.0001). In conclusion, BAV is complicated by progressive aortic dilation beginning in childhood.

Adolescent↗

Comparison of the pattern of aortic dilation in children with the Marfan's syndrome versus children with a bicuspid aortic valve.

Marfan's syndrome (MS) and bicuspid aortic valves (BAVs) are associated with aortic dilation. Despite their histologic similarities, the 2 diseases differ with regard to the location of maximal aortic dilation. Echocardiographic analysis of aortic dimensions was performed in children with MS, children who had aortic dilation in the setting of nonstenotic BAVs (peak gradient <16 mm Hg), and healthy controls. Data on 25 patients with MS, 31 with BAVs, and 65 controls were analyzed. Subjects with BAVs had greater dimensions at all levels of the aortic root compared with normal controls. Patients with BAVs also had greater dilation than those with MS at the level of the annulus and the ascending aorta, with dilation often extending cranially beyond the region of measurement. Conversely, patients with MS had more focal dilation at the sinuses of Valsalva compared with controls and patients with BAVs. In conclusion, despite similar histologic abnormalities, the anatomic pattern of aortic dilation differs in children with MS and BAVs.

Aorta↗

Morphology and function of the bicuspid aortic valve with and without coarctation of the aorta in the young.

This study sought to determine the morphology and function of bicuspid aortic valves (BAVs) with and without coarctation of the aorta (CoA) in a young population. The transthoracic echocardiograms of 117 patients with BAVs and 62 patients with CoA were retrospectively reviewed and compared with normal transthoracic echocardiographic results. In each patient, the area subtended by the aortic cusps and valve and the diameters of the aortic root at different levels were measured, and additionally in each BAV, the type of cusp fusion and the presence and degree of aortic stenosis and/or regurgitation were evaluated. The median age of patients with BAVs was 4 years (range 0 days to 34 years), and the median age of patients with CoA was 1.9 years (range 0 days to 16.5 years). BAVs with right and left coronary cusp fusion were significantly associated with CoA (p <0.0001) and cardiac anomalies (p <0.0001), whereas BAVs with noncoronary and right coronary cusp fusion were affected by valvar dysfunction (p <0.001). Compared with normal tricuspid aortic valves, BAVs had aortic root dilation, even in patients with no hemodynamic disturbance, particularly at the level of the ascending aorta (p <0.0001); the difference was still significant comparing BAVs and CoA with tricuspid aortic valves and CoA (p <0.0001). In conclusion, different morphologies of BAVs are associated with different cardiac abnormalities, valvar function, and aortic root dilation. Although detectable early in life, valvar dysfunction and aortic root dilation progress with age.

Adolescent↗

Novel missense mutations (p.T596M and p.P1797H) in NOTCH1 in patients with bicuspid aortic valve.

The bicuspid aortic valve (BAV) is the most common congenital cardiac malformation, occurring in 1-2% of the population. In a recent report, mutations in NOTCH1 a signaling and transcriptional regulator have been shown to cause BAV in two families. This study provides data on systematic sequencing in search for novel mutations in NOTCH1 gene in a large sample BAV. For the first time, we report results of a systematic mutation-analysis based on DNA-sequencing of all coding exons and adjacent splice consensus sequences of NOTCH1 gene. Our analyses revealed 57 NOTCH1 sequence variants. Twenty-one variants are located within exons and 36 within intronic or 5'-UTR sequences. Thirty-five variants were described previously as polymorphisms. The remaining 22, however, were neither listed in public SNP databases nor in the literature and were therefore considered novel. Seventeen variants were found only once (MAF = 1%), of these 15 were novel. Two sequence variants led to amino acid substitutions (p.T596M and p.P1797H) and are located in highly conserved regions of the NOTCH1 protein. In addition, these two mutations could not be detected in at least 327 healthy controls by using RFLP-analysis. The functional relevance of the other 13 novel and rare variants could not be proven without further functional examination. In this study, we provide a new evidence that the mutations in the NOTCH1 gene may trigger the underlying mechanism causing the valve calcification, especially in BAV. In conclusion, NOTCH1 gene mutations do not only play a role in familiar BAV, but can also be observed in approximately 4% of sporadic cases.

Adult↗