Clinical significance of the bicuspid aortic valve

Aortopathy is prevalent in relatives of bicuspid aortic valve patients

OBJECTIVES

This study aimed to determine the prevalence of dilation and abnormal elastic properties of aortic root in first-degree relatives (FDRs) of bicuspid aortic valve (BAV) patients.

BACKGROUND

Evidence indicates that BAV is a genetic disorder. Although FDRs of affected individuals have an increased prevalence of BAV, their risk of aortic root abnormalities is unknown.

METHODS

We studied dimensions as well as the elastic properties of the ascending aorta in 48 FDRs with morphologically normal tricuspid aortic valves, 54 BAV patients, and 45 control subjects using 2-dimensional echocardiography.

RESULTS

The prevalence of aortic root dilation was 32% in FDRs and 53% in BAV patients, whereas all control subjects showed normal aortic dimensions (p < 0.001). The FDRs and BAVs had significantly lower aortic distensibility (1.7 +/- 1.4 x 10(-3) mm Hg and 1.4 +/- 2.0 x 10(-3) mm Hg vs. 2.5 +/- 1.6 x 10(-3) mm Hg, p < 0.001) and greater aortic stiffness index (26.7 +/- 25.8 and 55.9 +/- 76.8 vs. 18.7 +/- 40.1, p = 0.001) compared with control subjects. This difference remained significant in subjects without aortic root dilation or hypertension (p = 0.002 and p = 0.004, respectively).

CONCLUSIONS

The aortic root is functionally abnormal and dilation is common (32%) in first-degree relatives of patients with BAV. Screening of FDRs by transthoracic 2-dimensional echocardiography should be considered for detection of aortic valve malformation and dilated ascending aorta.

Basal and oxidative stress-induced expression of metallothionein is decreased in ascending aortic aneurysms of bicuspid aortic valve patients

BACKGROUND

Bicuspid aortic valve (BAV) is a heritable condition that has been linked by an unknown mechanism to a predisposition for ascending aortic aneurysm. Matrix metalloproteinases have been implicated in this predisposition. Metallothionein is a poorly characterized, metal-binding protein that regulates matrix metalloproteinases and is an antioxidant known to be upregulated under oxidative stress.

METHODS AND RESULTS

To determine putative factors involved in the pathogenesis of aortic aneurysm in BAV patients, our first goal was to identify genes that are dysregulated in ascending aortic aneurysms of BAV patients compared with tricuspid aortic valve patients and nondiseased (control) donors. By microarray analysis (22,000 probe sets), 110 dysregulated genes were identified in BAV compared with tricuspid aortic valve patients and control donors; 8 were genes of the metallothionein family. Metallothionein gene expression and protein expression were significantly lower in aortic tissue and cultured aortic smooth muscle cells from BAV patients compared with control subjects. Matrix metalloproteinase-9 expression was increased in BAV aortic samples relative to controls. BAV aorta was more susceptible to oxidative stress, and induction of metallothionein under oxidative stress was reduced in BAV patients compared with control subjects.

CONCLUSIONS

These results demonstrate dysregulated metallothionein expression in ascending aortic smooth muscle cells of BAV patients that may contribute to an inadequate response to oxidative stress and provoke aneurysm formation. We hypothesize that metallothionein plays a pivotal role in the response of ascending aortic smooth muscle cells to oxidative stress cues normally involved in the maintenance of the extracellular matrix, including the regulation of matrix metalloproteinase expression.

Mitral regurgitation due to myxomatous degeneration combined with bicuspid aortic valve disease is often due to prolapse of the anterior leaflet of the mitral valve

BACKGROUND

This study examines the clinical, echocardiographic, surgical, and pathologic features of patients who had heart valve operations for combined congenital bicuspid aortic valve and mitral regurgitation due to degenerative disease of the mitral valve.

METHODS

A retrospective review of 1595 patients who had procedures for mitral regurgitation due to degenerative disease of the mitral valve and 1820 patients who had procedures for congenital bicuspid aortic valve disclosed 29 patients who had combined diseases.

RESULTS

The most common morphology of the bicuspid aortic valve was type 1 (fused right and left aortic cusps). Mitral regurgitation in 21 of 29 patients was caused by prolapse of the anterior leaflet, which was exceptionally large (mean height, 36.5 +/- 6.6 mm). Patients with prolapsed anterior leaflet of the mitral valve were younger (48 +/- 13 years vs 58 +/- 16 years, p = 0.01) and 95% were men. The bicuspid aortic valve was incompetent in 19 of 21, and the aortic annulus exceeded 30 mm in 20 of 21 patients.

CONCLUSIONS

Patients with combined mitral regurgitation due to myxomatous degeneration and bicuspid aortic valve disease who require operations often have a large, prolapsing anterior leaflet of the mitral valve and dilated aortic annulus with aortic insufficiency due to cusp prolapse.

The presence of bicuspid aortic valve does not predict ventricular septal defect type

Previous studies have identified an increased incidence of bicuspid aortic valve (BAV) in patients with ventricular septal defect (VSD). Because endocardial cushion remodeling contributes to both the formation of semilunar valves and ventricular septation, we hypothesized that examination of humans with BAV and VSD would identify a specific VSD type. We evaluated VSD type in pediatric patients diagnosed with BAV and VSD (n=82) and compared findings to patients diagnosed with VSD and normal aortic valve morphology (n=429). VSD type was described as conoventricular, muscular, inlet or conoseptal using a clinical taxonomy. Based on the contribution of the outflow tract endocardial cushions to the membranous ventricular septum, we expected patients with BAV to have conoventricular VSD. In both patient groups, conoventricular VSD was most common; however, the prevalence was not significantly different when BAV patients were compared to those with normal aortic valve morphology (67% vs. 57%, P=0.11). The primary finding of this study is that despite a developmental link between semilunar valve formation and ventricular septation during cardiogenesis, there is no clear association between BAV and VSD type. This may be due to phenotypic and genetic heterogeneity of BAV and VSD, other modifying factors as manifested by differences in associated CVM, as well as limitations of the clinical taxonomy of VSD.

Impact of bicuspid aortic valve on complications and death in infective endocarditis of native aortic valves

We retrospectively investigated the impact of bicuspid aortic valve on the prognosis of patients who had definite infective endocarditis of the native aortic valve.Of 51 patients, a bicuspid aortic valve was present in 22 (43%); the other 29 had tricuspid aortic valves. On average, the patients who had bicuspid valves were younger than those who had tricuspid valves. Patients with a tricuspid valve had larger left atrial diameters and were more likely to have severe mitral regurgitation.Periannular complications, which we detected in 19 patients (37%), were much more common in the patients who had a bicuspid valve (64% vs 17%, P = 0.001). The presence of a bicuspid valve was the only significant independent predictor of periannular complications. The in-hospital mortality rate in the bicuspid group was lower than that in the tricuspid group; however, this figure did not reach statistical significance (9% vs 24%, P = 0.15). In multivariate analysis, left atrial diameter was the only independent predictor associated with an increased risk of death (hazard ratio, 2.19; 95% confidence interval, 1.1-4.5; P = 0.031).In our study, patients with infective endocarditis in a bicuspid aortic valve were younger and had a higher incidence of periannular complications. Although a worse prognosis has been reported previously, we found that infective endocarditis in a native bicuspid aortic valve is not likely to increase the risk of death in comparison with infective endocarditis in native tricuspid aortic valves.

Is aortic wall degeneration related to bicuspid aortic valve anatomy in patients with valvular disease?

OBJECTIVE

Patients with bicuspid aortic valve are at increased risk for aortic complications.

METHODS

A total of 115 consecutive patients with bicuspid aortic valve disease underwent surgery of the ascending aorta. We classified the cusp configuration by 3 types: fusion of left coronary and right coronary cusps (type A), fusion of right coronary and noncoronary cusps (type B), and fusion of left coronary and noncoronary cusps (type C). Histopathologic changes in the ascending aortic wall were graded (aortic wall score).

RESULTS

We observed type A fusion in 85 patients (73.9%), type B fusion in 28 patients (24.3%), and type C fusion in 2 patients (1.8%). Patients with type A fusion were younger at operation than patients with type B fusion (51.3 +/- 15.5 years vs 58.7 +/- 7.6 years, respectively; P = .034). The mean ascending aorta diameter was 48.9 +/- 5.0 mm and 48.7 +/- 5.7 mm in type A and type B fusion groups, respectively (P = .34). The mean aortic root diameter was significantly larger in type A fusion (4.9 +/- 6.7 mm vs 32.7 +/- 2.8 mm; P < .0001). The aortic wall score was significantly higher in type A fusion than in type B fusion (P = .02). The prevalence of aortic wall histopathologic changes was significantly higher in type A fusion. Moreover, there were no statistically significant differences between type A and type B fusion in terms of prevalence of bicuspid aortic valve stenosis, regurgitation, or mixed disease.

CONCLUSION

In diseased bicuspid aortic valves, there was a statistically significant association between type A valve anatomy and a more severe degree of wall degeneration in the ascending aorta and dilatation of the aortic root at younger age compared with type B valve anatomy.

Dilatation of the ascending aorta in bicuspid aortic valve disease: a magnetic resonance imaging study

BACKGROUND

Bicuspid aortic valve disease (BAV) is increasingly recognized as a disease of the entire proximal aorta including both valvular and vascular complications. The aim of our study was to assess the dimensions of the thoracic aorta using MRI in a broad spectrum of BAV and tricuspid aortic valve disease (TAV) and to define the prevalence of the dilatation of the ascending aorta (AA) >or= 4.5 cm in severe BAV disease.

METHODS AND RESULTS

MRI studies were performed on a 1.5 T scanner in a total of 195 consecutive patients with aortic valve disease. Eighty-four aortic valves were classified as BAV and 103 as TAV. In 8 patients, classification of the aortic valve was not possible due to poor image quality. Mean diameters of the AA were significantly greater in BAV compared to TAV (4.39+/-0.85 Vs. 3.55+/-0.47 cm, P<0.0001), whereas no differences were observed in the mean diameters of the aortic arch. Diameters of the descending aorta were slightly smaller in BAV compared to TAV (2.45+/-0.43 Vs. 2.58+/-0.31 cm, P<0.05). In BAV, AA dilatation was independent of the severity of valve dysfunction. In TAV, aortic regurgitation but not stenosis correlated weakly with AA dilatation. Prevalence of AA dilatation >or= 4.5 cm in BAV with severe aortic stenosis and regurgitation was 38% and 41%, respectively.

CONCLUSION

Dilatation of the proximal aorta is a frequent finding in BAV and independent of the severity of valve dysfunction. With respect to the high prevalence of AA dilatation >or= 4.5 cm in BAV with severe valve dysfunction, careful assessment of the dimensions of the AA is crucial to identify patients in whom concomitant AA replacement is indicated according to current guidelines.

Pathophysiology, diagnosis, and management of aortic dissection

Aortic dissection is an uncommon but potentially fatal disease with catastrophic complications. A high level of suspicion is required for successful diagnosis as presenting symptoms are so variable that dissection may be overlooked in up to 39% of cases. It most commonly presents in the elderly population with a history of chronic hypertension. Rapid intervention is necessary as delay leads to higher mortality. Despite advances in diagnostic and therapeutic techniques, morbidity and mortality remains high. Advances in diagnostic imaging have raised the awareness of variants of aortic dissection, including intramural hemorrhage and penetrating aortic ulcer. This distinction is important as the clinical course of these variants differs from that of classical aortic dissection, and thus treatment may also differ. Understanding of these variants has also led to the recognition of markers that may help predict progression to classical aortic dissection and thus warrant closer vigilance in selected patient populations. The recognition that rapid diagnosis is required for management of aortic dissection has led to the investigation of serum tests as diagnostic aids. Serum smooth muscle myosin heavy chain, d-dimer, and serum soluble elastin fragments are promising tests that may help raise suspicion for the diagnosis of acute aortic dissection. The high mortality associated with surgical therapy has led to investigation of alternative approaches. Endovascular therapy has emerged as a viable option in patients with type B dissection who are too unstable for surgery. However, long-term follow up is required to validate this procedure.

Descending Thoracic Aortic Dissection: Evaluation and Management in the Era of Endovascular Technology

Acute aortic dissection is a relatively uncommon but highly lethal condition. Without proper treatment, devastating consequences can occur due to aortic rupture, cardiac tamponade, or irreversible ischemia involving the spinal cord or the visceral organs. The treatment strategy of this condition is in part influenced by the location and the severity of aortic dissection as immediate surgical intervention is necessary in acute ascending aortic dissection, whereas medical therapy is the initial treatment approach in uncomplicated descending aortic dissection. Recent advances of endovascular technology have broadened the potential application of this catheter-based therapy in aortic pathologies, including descending thoracic aortic dissection. In this article, the etiology, pathogenesis, and classification of this condition are discussed. The diagnostic benefits of various imaging modalities for descending aortic dissection are also discussed. Current treatment strategies, including medical, surgical, and catheter-based interventions, are reviewed. Lastly, clinical experiences of endovascular treatment for descending aortic dissection and various endovascular devices potentially applicable for this condition are discussed.

Toward predictable repair of regurgitant aortic valves: a systematic morphology-directed approach to bicommissural repair

OBJECTIVES

Our purpose was to investigate a new approach to bicommissural repair of regurgitant aortic valves.

BACKGROUND

Repair of regurgitant aortic valves is not widely accepted, but interest is increasing, particularly for bicuspid valves. We hypothesize that a systematic, segmental approach to morphology and corresponding morphology-directed repair will improve decision making and success.

METHODS

From December 2001 to July 2007, a systematic surgical approach to valve analysis and bicommissural repair was applied prospectively to 63 consecutive patients with pure aortic valve regurgitation, mean age 40 +/- 12 years. Cusp, commissure, and root morphologies were analyzed sequentially by direct inspection. Each abnormality was corrected by corresponding morphology-directed repair procedures. Retrospectively, 2 echocardiographic indexes--of tissue pliability (change in systolic to diastolic area) and coaptation deficiency (conjoint and reference cusp heights vs. "annulus" diameter)--were developed to evaluate repairability.

RESULTS

Forty-two (67%) valves were repaired and 21 (33%) replaced. Regurgitation was related primarily to cusp (prolapse, restriction) and commissure (splaying) morphology; root pathology was less important. Morphology-directed repair included cusp maneuvers in all, commissural maneuvers in 71%, and root procedures in 33%. Restriction and cusp tissue deficiency limited repairability. Echocardiography reflected this in greater tissue pliability of successfully repaired valves compared with replaced ones (conjoint cusp 61 +/- 16% vs. 34 +/- 17%; reference cusp 65 +/- 16% vs. 42 +/- 16%; p = 0.0001) and less coaptation deficiency (1.06 +/- 0.24 for repaired and 1.27 +/- 0.19 for replaced valves; p = 0.002).

CONCLUSIONS

Systematic segmental analysis of morphology and a logical morphology-directed surgical approach facilitate aortic valve repair. Initial application of this paradigm suggests sufficient mobile cusp tissue is a key determinant of repairability.

Management of the ascending aorta in patients with bicuspid aortic valve disease

Bicuspid aortic valve (BAV) disease is the most common form of congenital heart disease, affecting 1-2% of the population. Only 20% of patients will maintain normal valve function throughout their life and more than 30% of patients will develop serious morbidity. It is a highly heritable condition, with transmission likely to be autosomal dominant. Patients with BAV have a 10-fold risk of aortic dissection when compared to the normal population. Management of BAV associated aortopathy represents a significant clinical challenge.

Surgical repair of cardiac valves

The mitral, aortic, and tricuspid valves can be repaired, in experienced hands. Durability of repair, especially for the mitral valve, compares favorably to valve replacement. Repair of cardiac valves enables many patients to be free of life-long anticoagulation, maintain their native valve structure, reduce their risk for endocarditis, and avoid complications associated with prosthetic valve implants.

Differential protein kinase C isoform abundance in ascending aortic aneurysms from patients with bicuspid versus tricuspid aortic valves

BACKGROUND

It is recognized that different events contribute to the initiation of ascending thoracic aortic aneurysms (ATAAs) in patients with bicuspid aortic valves (BAV) versus patients with tricuspid aortic valves (TAV), but the molecular signaling pathways driving aneurysm formation remain unclear. Protein kinase C (PKC) is a superfamily of kinases which differentially mediate signaling events that lead to altered gene expression and cellular function, and may regulate downstream mediators of vascular remodeling. The present study tested the hypothesis that ATAA development in patients with BAV versus TAV proceeds by independent signaling pathways involving differential PKC signaling.

METHODS AND RESULTS

ATAA samples were collected from BAV (n=57) and TAV (n=55) patients and assessed for 10 different PKC isoforms by immunoblotting. Results were expressed as a percent change in abundance (mean+/-SEM) from a nonaneurysmal control group (100%, n=21). Correlation analysis was performed, and relationships between PKC and matrix metalloproteinase abundance were reported. In the BAV group, classic and novel PKC isoforms (PKC-alpha, betaI, gamma, epsilon, theta) were increased, whereas PKC-eta and atypical PKC-zeta were decreased. In the TAV group, classic and novel isoforms were decreased and atypical PKC-zeta was elevated. Positive correlations between PKC and matrix metalloproteinase abundance were identified.

CONCLUSIONS

Differential PKC isoform abundance was observed in ATAA samples from patients with BAV versus TAV, suggesting independent molecular signaling pathways may be operative. Induction of independent transcriptional programs may result and may provide a mechanistic foundation for developing selective diagnostic/therapeutic strategies for patients with ATAAs secondary to BAV or TAV.

Long-Term Survival After the Bentall Procedure in 206 Patients With Bicuspid Aortic Valve

BACKGROUND

The recognition that patients with a bicuspid aortic valve (BAV) are at risk for aorta-related death (rupture or dissection) has favored composite aortic root replacement in BAV patients who undergo aortic valve replacement for valve dysfunction as well as in asymptomatic BAV patients with significant aortic root dilatation. We report the results of Bentall operations in 206 BAV patients during an 18-year interval.

METHODS

Two hundred six BAV patients (mean, 53 +/- 14 years, 84% male) underwent composite aortic root replacement between September 1987 and May 2005. One hundred nine patients (53%) presented with aortic regurgitation, 24 patients (12%) presented with aortic stenosis, and 55 patients (26%) presented with combined aortic stenosis and aortic regurgitation. Median preoperative aortic diameter was 5.5 cm (range, 3 to 9 cm). Twenty-two patients (11%) underwent urgent or emergent procedures; 11 had acute type A dissection (5%). Sixty-one percent had a mechanical valve Bentall prosthesis; in 39%, a biologic valve was implanted. Thirty-two percent had concomitant procedures.

RESULTS

Overall hospital mortality was 2.9% (n = 6), and stroke rate was 1.9% (n = 4). Risk factors for adverse outcome (death or stroke), which occurred in 4.8% (n = 10), were presence of clot or atheroma (p = 0.02) and age older than 65 years (p = 0.05). During a mean follow-up of 5.9 years (1,200 patient-years; range, 5 to 18 patient-years), no patient required ascending aortic reoperation. Long-term survival was 93% after 5 years and 89% after 10 years. Discharged patients enjoyed survival equivalent to a normal age- and sex-matched population and superior to survival reported for a series of patients with aortic valve replacement alone.

CONCLUSIONS

In patients with BAV, the Bentall procedure has an operative mortality no worse than that for aortic valve replacement, with superior long-term survival and a lower rate of aortic reoperation.

Novel NOTCH1 mutations in patients with bicuspid aortic valve disease and thoracic aortic aneurysms

OBJECTIVES

Bicuspid aortic valve is a common condition and is associated with a significantly increased risk of developing thoracic aortic aneurysms and acute aortic dissection. Patient-specific prediction of the risk of developing thoracic aortic aneurysm, however, is imprecise. We hypothesize that genotypic variations in patients with bicuspid aortic valves contribute to this observed variability in aortic phenotype. We, therefore, investigated the potential relationship between mutations in regions of NOTCH1 recently reported to be associated with bicuspid aortic valve and the phenotype of bicuspid aortic valve and thoracic aortic aneurysms in unrelated patients undergoing surgical repair.

METHODS

We performed a targeted mutational analysis of NOTCH1 using genomic DNA from 48 unrelated subjects with concomitant bicuspid aortic valve and thoracic aortic aneurysm using denaturing high-performance liquid chromatography and DNA sequencing. We focused on exons in which mutations associated with bicuspid aortic valve have been reported previously. Results were compared with control subjects with trileaflet aortic valves (n = 94), bicuspid aortic valves, and normal aortas (n = 22) and in subjects with tricuspid aortic valves and thoracic aortic aneurysms (n = 28).

RESULTS

Four unique, nonsynonymous (3 novel) variants were identified in 5 (10.4%) of 48 patients with concomitant bicuspid aortic valves and thoracic aortic aneurysms compared with only 3 (2.1%) of 144 control subjects (P = .02). Of these, 2 novel missense mutations, A1343V and P1390T, were observed only in patients with bicuspid aortic valves and tricuspid aortic aneurysms.

CONCLUSIONS

This targeted analysis involving NOTCH1 exons previously implicated in familial and sporadic bicuspid aortic valve demonstrates overrepresentation of NOTCH1 missense variants among patients with bicuspid aortic valves and thoracic aortic aneurysms. Identification of aneurysm-predisposing susceptibility genes may lead to gene-directed surgical therapy of the ascending aorta for patients with bicuspid aortic valves.

Proteomic alterations in heat shock protein 27 and identification of phosphoproteins in ascending aortic aneurysm associated with bicuspid and tricuspid aortic valve

Whether or not there are molecular differences, at the intra- and extracellular level, between aortic dilatation in patients with bicuspid (BAV) and those with a tricuspid aortic valve (TAV) has remained controversial for years. We have performed 2-dimensional gel electrophoresis and mass spectrometry coupled with dephosphorylation and phosphostaining experiments to reveal and define protein alterations and the high abundant structural phosphoproteins in BAV compared to TAV aortic aneurysm samples. 2-D gel patterns showed a high correlation in protein expression between BAV and TAV specimens (n=10). Few proteins showed significant differences, among those a phosphorylated form of heat shock protein (HSP) 27 with significantly lower expression in BAV compared to TAV aortic samples (p=0.02). The phosphoprotein tracing revealed four different phosphoproteins including Rho GDP dissociation inhibitor 1, calponin 3, myosin regulatory light chain 2 and four differentially phosphorylated forms of HSP27. Levels of total HSP27 and dually phosphorylated HSP27 (S78/S82) were investigated in an extended patient cohort (n=15) using ELISA. Total HSP27 was significantly lower in BAV compared to TAV patients (p=0.03), with no correlation in levels of phospho-HSP27 (S78/S82) (p=0.4). Western blots analysis showed a trend towards lower levels of phospho-HSP27 (S78) in BAV patients (p=0.07). Immunohistochemical analysis revealed that differences in HSP27 occur in the cytoplasma of VSMC's and not extracellularly. Alterations in HSP27 may give early evidence for intracellular differences in aortic aneurysm of patients with BAV and TAV. Whether HSP27 and the defined phosphoproteins have a specific role in BAV associated aortic dilatation remains to be elucidated.

Type B aortic dissection associated with coarctation of the aorta

We describe a case of acute type B dissection associated with coarctation of the aorta, a rare pathological combination. An intimal tear was located just distal to the coarctation. Aortic dilatation started below the coarctation and extended to the level of the diaphragm. We performed descending aorta replacement from the distal aortic arch to the level of the 9th intercostal arteries through a left posterolateral thoracotomy in the fifth intercostal space. Arterial cannulations were placed on the right femoral artery and just proximal to the coarctation site in the descending aorta. To preserve the patent 10th and lower intercostal arteries, longitudinal plication of dilated pseudo-lumen was applied from the distal cut end to the level of the diaphragm. The postoperative course was uneventful.

Infective endocarditis in bicuspid aortic valve: atrioventricular block as sign of perivalvular abscess

A 46-year-old man presenting with fever, peripheral edema, and chest pain was admitted to the emergency department. Electrocardiogram showed sinus tachycardia and first-degree atrioventricular block. Transesophageal echocardiogram showed infective endocarditis in bicuspid aortic valve, complicated with severe aortic regurgitation, ring abscess, and sinus-of-Valsalva aneurysm extending to mitroaortic fibrous continuity. The patient, who was unaware of his bicuspid aortic valve condition, reported having undergone an orthodontic procedure complicated with dental abscess 1 month prior, which was treated with combined clavulanate-amoxicillin antibiotic therapy. Blood cultures were positive for Bacteroides fragilis resistant to metronidazole. Intravenous antibiotic therapy was undertaken, with rapid resolution of fever. He eventually underwent successful aortic homograft implantation and mitral valve repair with residual first-degree atrioventricular block.

Clinical outcome and echocardiographic predictors of aortic valve replacement in patients with bicuspid aortic valve

BACKGROUND

Clinical outcomes and echocardiographic parameters associated with aortic valve replacement (AVR) for bicuspid aortic valve are scarce.

METHODS

We conducted retrospective analysis of 208 adults with bicuspid aortic valve referred for transthoracic echocardiograms.

RESULTS

The Kaplan-Meier survival free of death or need for cardiac surgery was 72% at 5 years. Cardiac surgery was performed in 19%, the majority (68%) for symptomatic aortic stenosis. Peak gradient 80 mm Hg or greater (hazard ratio 11.8, 95% confidence interval 3.7-37.8, P < .0001) and aortic valve area less than or equal to 0.75 cm(2) (hazard ratio 2.9, 95% confidence interval 1.0-8.5, P = .05) predicted the need for AVR. Patients with a large (54%) versus normal left ventricular outflow tract dimension underwent AVR for symptomatic aortic stenosis at a larger calculated aortic valve area (1.07 +/- 0.21 vs 0.75 +/- 0.18 cm(2), P < .0001) but at a similar peak gradient and velocity ratio (76 +/- 19 vs 76 +/- 22 mm Hg, P = not significant; 0.23 +/- 0.06 vs 0.26 +/- 0.12, P = not significant, respectively).

CONCLUSIONS

Clinical events are common among patients with bicuspid aortic valve. Peak gradient 80 mm Hg or more and aortic valve area less than or equal to 0.75 cm(2) predicts the need for AVR. Gradients and velocity ratio better reflect the hemodynamic burden of aortic stenosis in patients with a large left ventricular outflow tract.

Bicuspid Aortic Valve Morphology and Interventions in the Young

OBJECTIVES

The aim of this study was to determine whether the morphologic subtype of bicuspid aortic valve (BAV) is associated with valve intervention in the young.

BACKGROUND

Analysis of BAV morphology is of prognostic relevance, as the fusion of right- and noncoronary leaflets (R-N) is associated with a greater degree of valve dysfunction compared with other subtypes. However, it is currently unknown whether morphologic differences translate into clinically relevant outcomes such as valve intervention.

METHODS

A nested cohort study was conducted on 310 patients with right- and left-coronary leaflet (R-L) and R-N fusion who were selected randomly from an inception cohort of 1,192 patients with BAV who were identified between 1986 and 1999. Supplementary information on clinical parameters was collected retrospectively from medical charts and databases.

RESULTS

Median age at follow-up was 16.1 years (range 5.6 to 34.4 years), and 71% were male. The R-N fusion (n = 108) was strongly predictive of valve intervention when compared with The R-L fusion (n = 202; hazard ratio 4.5, 95% confidence interval [CI] 2.5 to 8.1; p < 0.0001). In a longitudinal analysis of 799 echocardiograms, R-N fusion also was associated with a greater progression of valve dysfunction. This was true for both increasing aortic valve gradient (generalized estimating equations [GEE] risk ratio 27.2, 95% CI 1.2 to 619.6, p = 0.0386) and aortic regurgitation (GEE risk ratio 2.4, 95% CI 1.3 to 4.3, p = 0.0029).

CONCLUSION

The morphology of BAV is predictive of clinically important end points. The R-N fusion is associated with a more rapid progression of aortic stenosis and regurgitation and a shorter time to valve intervention.

A classification system for the bicuspid aortic valve from 304 surgical specimens

OBJECTIVE

In general, classification of a disease has proven to be advantageous for disease management. This may also be valid for the bicuspid aortic valve, because the term "bicuspid aortic valve" stands for a common congenital aortic valve malformation with heterogeneous morphologic phenotypes and function resulting in different treatment strategies. We attempted to establish a classification system based on a 5-year data collection of surgical specimens.

METHODS

Between 1999 and 2003 a precise description of valve pathology was obtained from operative reports of 304 patients with a diseased bicuspid aortic valve. Several different characteristics of bicuspid aortic valves were tested to generate a pithy and easily applicable classification system.

RESULTS

Three characteristics for a systematic classification were found appropriate: (1) number of raphes, (2) spatial position of cusps or raphes, and (3) functional status of the valve. The first characteristic was found to be the most significant and therefore termed "type." Three major types were identified: type 0 (no raphe), type 1 (one raphe), and type 2 (two raphes), followed by two supplementary characteristics, spatial position and function. These characteristics served to classify and codify the bicuspid aortic valves into three categories. Most frequently, a bicuspid aortic valve with one raphe was identified (type 1, n = 269). This raphe was positioned between the left (L) and right (R) coronary sinuses in 216 (type 1, L/R) with a hemodynamic predominant stenosis (S) in 119 (type 1, L/R, S). Only 21 patients had a "purely" bicuspid aortic valve with no raphe (type 0).

CONCLUSIONS

A classification system for the bicuspid aortic valve with one major category ("type") and two supplementary categories is presented. This classification, even if used in the major category (type) alone, might be advantageous to better define bicuspid aortic valve disease, facilitate scientific communication, and improve treatment.

Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

The intent of this review is to provide the clinician with a summary of what is currently known about the contribution of genetics to the origin of congenital heart disease. Techniques are discussed to evaluate children with heart disease for genetic alterations. Many of these techniques are now available on a clinical basis. Information on the genetic and clinical evaluation of children with cardiac disease is presented, and several tables have been constructed to aid the clinician in the assessment of children with different types of heart disease. Genetic algorithms for cardiac defects have been constructed and are available in an appendix. It is anticipated that this summary will update a wide range of medical personnel, including pediatric cardiologists and pediatricians, adult cardiologists, internists, obstetricians, nurses, and thoracic surgeons, about the genetic aspects of congenital heart disease and will encourage an interdisciplinary approach to the child and adult with congenital heart disease.

Endothelial nitric oxide synthase in bicuspid aortic valve disease

BACKGROUND

The pathogenesis of ascending aortic dilatation in the presence of a bicuspid valve is discussed controversially. Recent experimental evidence suggests that the expression of endothelial nitric oxide synthase (eNOS) may have an influence on aortic valve anatomy and aneurysmal dilatation of the aorta. We investigated the relationship among eNOS expression, valve anatomy, and aortic dilatation in the human aortic wall.

METHODS

Aortic wall specimens from 39 patients with aortic valve disease (bicuspid, n = 17; tricuspid, n = 22) were studied. The functional aortic valve pathology was regurgitation (n = 22), stenosis (n = 10), and combined aortic valve disease (n = 7). The specimens were obtained intraoperatively from the aortic wall above the noncoronary sinus. The eNOS protein expression was quantified by western blot analysis after immunoprecipitation from tissue lysates. The eNOS levels were analyzed for correlation with valve anatomy and ascending aortic diameters.

RESULTS

The eNOS protein expression of aortic endothelial cells was significantly lower in patients with bicuspid as compared with tricuspid aortic valves (4,615 +/- 489 vs 6,275 +/- 442; p = 0.017). In bicuspid aortic valves there was a significant correlation between eNOS expression and maximum aortic diameter (r = -0.530; p = 0.029) or sinotubular diameter (r = -0.520; p = 0.033). In patients with tricuspid aortic valves, no significant correlation between aortic size and eNOS expression was found.

CONCLUSIONS

Our results show an association between eNOS levels and aortic valve anatomy as well as aneurysm formation in patients with bicuspid aortic valves.

An undiagnosed bicuspid aortic valve can result in severe left ventricular failure

Asymptomatic bicuspid aortic valves diagnosed in childhood need regular monitoring to allow early surgical intervention and prevention of left ventricular failure

Elevated expressions of osteopontin and tenascin C in ascending aortic aneurysms are associated with trileaflet aortic valves as compared with bicuspid aortic valves

OBJECTIVE

Ascending aortic aneurysms (AscAAs) are a highly lethal condition whose pathobiology remains to be poorly understood. Although most AscAAs occur in the presence of a trileaflet aortic valve (TAV), a bicuspid aortic valve (BAV) is a common congenital anomaly associated with an increased risk for an AscAA and dissection independent of functional valve pathology but secondary to inherent structural abnormality of the aorta. The objective of this investigation was to compare the patterns of gene expression in aortas between TAV and BAV patients with the aim of identifying markers for AscAAs.

METHODS

We used microarray analysis to first compare messenger RNA expressions between aneurysmal aortas from TAV patients (n=11) and those from BAV patients (n=11), identified genes overexpressed in TAV aneurysms, and compared expressions of the selected genes among TAV aneurysms, BAV aneurysms, and normal aortas (n=3). Finally, expressions of the selected genes were assessed by immunostaining of aortas from the TAV, BAV, and normal specimens.

RESULTS

Two overexpressed genes in the TAV group, osteopontin (OPN) and tenascin C (TNC), were consistently more highly expressed in TAV aneurysms than in BAV aneurysms and normal aortas as determined by real-time reverse transcriptase quantitative polymerase chain reaction and immunohistochemistry. Differential staining revealed that OPN protein was concentrated in the medial smooth muscle and that TNC protein was concentrated around the vasa vasorum.

CONCLUSIONS

We identified two novel potential markers, OPN and TNC, that are strongly associated with TAV aneurysms. The roles of OPN and TNC in influencing extracellular matrix remodeling in AscAAs warrant further investigation.

Preservation of the Bicuspid Aortic Valve

BACKGROUND

Bicuspid anatomy of the aortic valve is a common reason for aortic regurgitation and is associated with aortic dilatation in more than 50% of patients. We have observed different patterns of aortic dilatation and used different approaches preserving the valve.

METHODS

Between October 1995 and February 2006, a regurgitant bicuspid valve was repaired in 173 patients. The aorta was normal in 57 patients who underwent isolated repair. Aortic dilatation mainly above commissural level (n = 38) was treated by separate valve repair plus supracommissural aortic replacement. In 78 patients, aortic dilatation involved the root and was treated by root remodeling.

RESULTS

Hospital mortality and perioperative morbidity were low in all three groups. Myocardial ischemia was significantly shorter in repair plus aortic replacement than remodeling (p < 0.001). Freedom from aortic regurgitation II or greater at 5 years varied between 91% and 96%. Freedom from reoperation at 5 years was 97% after remodeling, but only 53% after repair plus aortic replacement (p = 0.33). Symmetric prolapse was the most frequent cause for reoperation.

CONCLUSIONS

The long-term stability of bicuspid aortic valve repair is excellent in the absence of aortic pathology. In the presence of aortic dilatation, root remodeling leads to equally stable valve durability. In patients with less pronounced root dilatation, separate valve repair plus aortic replacement may be a less complex alternative. Symmetric prolapse should be avoided if the ascending aorta is replaced.

Histopathological study of congenital aortic valve malformations in 32 children

The histopathological characteristics of congenital aortic valve malformations in children were investigated. All the native surgically excised aortic valves from 32 pediatric patients suffering from symptomatic aortic valve dysfunction due to congenital aortic valve malformations between January 2003 and December 2005 were studied macroscopically and microscopically. The patients' medical records were reviewed and the clinical information was extracted. The diagnosis was made by the clinical presentation, preoperative echocardiography, intraoperative examination, and postoperative histopathological study, excluding rheumatic or degenerative aortic valve diseases, infective endocarditis and primary connective tissue disorders, e.g. Marfan syndrome. Among 32 children with congenital aortic valve malformations, the age was ranged from six to 18 years, with a mean of 14.9 years, and there were 27 boys and five girls (male: female = 5.4:1). There were five cases of aortic stenosis (AS, 15.62%), 25 cases of aortic insufficiency (AI, 78.13%) and two cases of AS-AI (6.25%), without other valve diseases. Twenty cases still had other congenital heart diseases: ventricular septal defect (19 cases), patent ductus arteriosus (two cases), double-chambered right ventricle (one case), aneurysm of the right anterior aortic sinus of valsalva (three cases). Histopathological examination indicated that the cusps became thickening with unequal size, irregular shape (coiling and prolapse edge), enhanced hardness, and partly calcification. Microscopic investigation revealed the unsharp structure of valve tissue, fibrosis, myxomatous, reduced collagen fiber, rupture of elastic fibers, different degrees of infiltration of inflammatory cells, secondary calcareous and lipid deposit, and secondary fibrosis. Congenital aortic valve malformations in children involve males more than females, mostly associated with other congenital heart diseases. Aortic insufficiency is more common in children with congenital aortic valve malformations. Histopathologically, the leaflets of aortic valve are mainly myxomatous, thickening with unequal size, irregular shape (coiling and prolapse edge), reduced collagen fiber, rupture of elastic fibers, without small vessel proliferation and inflammatory cell infiltration, fibrosis and calcification rarely seen.

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.

Cardiomyopathy with a unique finding of bicuspid aortic valve in Becker's muscular dystrophy

We describe a patient with Becker's muscular dystrophy and cardiac failure caused by a combination of dilated cardiomyopathy and congenital bicuspid aortic valve with aortic stenosis. There is no documented association between congenital valve disease and human dystrophinopathies, and to our knowledge, this is the first reported case.

Echocardiographic follow-up of congenital aortic valvular stenosis

We investigated the morphology of the stenotic aortic valve, the progression of the stenosis, and the onset and progression of aortic regurgitation (AR) in patients with congenital aortic valvular stenosis (AVS). The medical records of 278 patients with AVS were reviewed, with the patients with concomitant lesions besides AR excluded. Very mild aortic stenosis was defined as a transvalvular Doppler peak systolic instantaneous gradient (PSIG) less than 25 mmHg, mild stenosis as 25-49 mmHg, moderate stenosis as 50-75 mmHg, and severe stenosis as more than 75 mmHg. The mean age of the patients was 4.9 +/- 4.3 years (range, 3 days to 15 years), and 203 (73%) were male. The number of the cusps was determined with two-dimensional echocardiography in 266 patients (95%): unicuspid in 3 patients (1%), bicuspid in 127 patients (48%), and tricuspid in 136 patients (51%). A total of 192 of all patients were followed for 2 months to 14.6 years (mean 4.2 +/- 3.3 years) with medical treatment alone. Among 72 patients with very mild stenosis at initial echocardiographic examination, 20% had mild, 3% moderate, and 1% severe stenosis after a mean period of 3.7 years. In 70 patients with mild stenosis at initial echocardiographic examination, 28% had moderate and 9% severe stenosis after a mean period of 5 years. Among 44 patients with moderate stenosis at initial echocardiographic examination, 36% had severe stenosis after a mean period of 3.7 years. Among 192 patients, 40% had AR (3% trivial, 28% mild, and 9% moderate) at initial echocardiographic examination. After a mean period of 4.2 years, 58% of the patients had AR (13 % trivial, 25% mild, 16% moderate, and 4% severe). There was not statistically significant difference between catheterization peak systolic gradients (47 +/- 16 mmHg) and Doppler estimated mean gradients (45 +/- 9 mmHg) (p = 0.53), whereas Doppler PSIGs (74.9 +/- 15.7 mmHg) were higher than catheterization peak systolic gradients (p < 0.0001) in 25 patients who were studied in the catheterization lab. Patients with very mild stenosis may be followed with a noninvasive approach every 1 or 2 years, and an annual follow-up is suggested for patients with mild stenosis. Nearly one-third of patients with moderate stenosis at initial echocardiographic examination had severe stenosis after a mean period of 3.7 years. Therefore, we recommend, that patients with moderate stenosis undergo noninvasive evaluation every 6 months. Doppler estimated mean gradient is very useful in predicting the need for intervention in children with AVS.

Effect of G-Force on Bicuspid Aortic Valve in Aviators

BACKGROUND AND AIMS

Bicuspid aortic valve (BAV) is a common congenital cardiac malformation. The major complications are aortic stenosis (AS), aortic regurgitation (AR), infectious endocarditis and aortic dissection. This paper aims to assess the hemodynamic importance of incidentally-found BAV in military aviators and evaluate the effect of high G-force on disease progression.

METHODS

Aviators with BAV were detected by reviewing all cardiac assessment records between 1987 and 2005. All aviators underwent annual flight surgeon examination. Echocardiography was performed as recommended by our cardiologists and flight surgeons.

RESULTS

Eight newly diagnosed cases of BAV were found. All of the aviators continued active aviation throughout the study period. Repeat echocardiography demonstrated progressive widening of the aortic diameter in five of the eight aviators. No worsening of valve dysfunction was seen in those with mild aortic regurgitation at diagnosis. Left ventricular dimensions and function did not deteriorate. No new valve complications, including infectious endocarditis, were seen. The age at diagnosis strongly correlated with the root diameter change; both total (r = 0.74, p = 0.02) and annualized (r = 0.78, p = 0.02) change. Over a mean follow-up period of 12.1 years, no difference was seen in the progression of BAV in high-performance as compared to low-performance aviators.

CONCLUSIONS

Exposure to G-force and anti-G maneuvers does not appear to worsen cardiac and valve function in aviators with BAV.

Bicuspid aortic valve and ascending aortic aneurysm are not associated with germline or somatic homeobox NKX2-5 gene polymorphism in 19 patients

BACKGROUND

Bicuspid aortic valve is the most common congenital anomaly, occurring in 1% to 2% of the population. It is the most common reason for aortic valve replacement, and such individuals are at significantly increased risk of aortic complications. Despite the clinical significance of bicuspid aortic valve, its genetic basis remains unclear. The homeobox gene NKX2-5 occupies a central position in the hierarchy of cardiac determinants, and mutations in this gene are associated with bicuspid aortic valve in mice. We therefore investigated the presence of mutations in NKX2-5 among patients with bicuspid aortic valve and associated aneurysm.

METHODS

Germline DNA was extracted from peripheral blood leukocytes and somatic DNA from diseased aortic tissues of 19 patients with bicuspid aortic valve and associated aortic aneurysm. Three patients with trileaflet aortic valve and aneurysm served as control subjects. The entire NKX2-5 coding sequence, including intron-exon boundaries, was screened for mutation by means of polymerase chain reaction, followed by DNA sequencing.

RESULTS

Direct sequencing revealed a change in somatic (aortic) DNA 239A-->G, leading to synonymous amino acid alteration of Glu21Glu in one patient with bicuspid aortic valve and 1 control subject. There were no other alterations detected in the coding regions of germline or somatic genes. A known polymorphic change in the 3' untranslated region adjacent to exon 2 was detected in both bicuspid aortic valve and control samples. Discrepancies between germline and somatic DNA sequences were observed.

CONCLUSION

Our study fails to demonstrate an association between bicuspid aortic valve and NKX2-5 mutation, as has been seen in mice. Our findings support the importance of sequencing somatic, as well as germline, DNA.

Extracellular Matrix Remodeling and Organization in Developing and Diseased Aortic Valves

Heart valve disease is an important cause of morbidity and mortality worldwide. Little is known about valve disease pathogenesis, but increasing evidence implicates a genetic basis for valve disease, suggesting a developmental origin. Although the cellular and molecular processes involved in early valvulogenesis have been well described, less is known about the regulation of valve extracellular matrix (ECM) organization and valvular interstitial cell (VIC) distribution that characterize the mature valve structure. Histochemistry, immunohistochemistry, and electron microscopy were used to examine ECM organization, VIC distribution, and cell proliferation during late valvulogenesis in chicken and mouse. In mature valves, ECM organization is conserved across species, and developmental studies demonstrate that ECM stratification begins during late embryonic cusp remodeling and continues into postnatal life. Cell proliferation decreases concomitant with ECM stratification and VIC compartmentalization. Explanted, stenotic bicuspid aortic valves (BAVs) from pediatric patients were also examined. The diseased valves exhibited disruption of the highly organized ECM and VIC distribution seen in normal valves. Cusps from diseased valves were thickened with increased and disorganized collagens and proteoglycans, decreased and fragmented elastic fibers, and cellular disarray without calcification or cell proliferation. Taken together, these studies show that normal valve development is characterized by spatiotemporal coordination of ECM organization and VIC compartmentalization and that these developmental processes are disrupted in pediatric patients with diseased BAVs.

Aortic dilatation in patients with bicuspid aortic valve

The association of a bicuspid aortic valve (BAV) with abnormalities of the proximal thoracic aorta, including dilatation, aneurysm and dissection, has been previously described, leading to the hypothesis of a common underlying developmental defect involving the aortic valve and the aortic wall. Consequently, any patient with BAV should receive a careful assessment not only of the valve function, but also of the aortic root and the ascending aorta. Dilatation of the proximal thoracic aorta is a common finding in patients with BAV and is believed to be related to aortic rupture and dissection. Because progressive dilatation can occur, careful long-term surveillance of the aortic dimensions is required. Prophylactic surgical repair of the dilated aorta should be recommended more aggressively for patients with BAV than for those with a tricuspid aortic valve. However, the optimal timing of aortic surgery in BAV patients remains uncertain because of the limited data available on the natural history of asymptomatic aortic dilatation.

Bicuspid aortic valve: an innocent finding or a potentially life-threatening anomaly whose complications may be elicited by sports activity?

The bicuspid aortic valve is the most frequent congenital anomaly of the heart in adults. Since the 1970s, with the advent of two-dimensional echocardiography, the in-vivo diagnosis of bicuspid aortic valve has become easier and greater attention has been paid to this anomaly in normal young people, particularly in sportsmen because, from a theoretical point of view, physical exercise may stress the abnormal aortic valve, favouring an early deterioration of the valve itself, as well as a dilation of the ascending aorta. Although the bicuspid aortic valve may remain without clinical consequences for a lifetime, it may be responsible for severe complications such as aortic stenosis, aortic insufficiency, endocarditis and aortic dilation/dissection, sometimes requiring surgery. Moreover, the bicuspid aortic valve may be associated with other cardiovascular anomalies, mainly aortic coarctation. At present there are no prospective studies dealing with effect of physical training and competitive sports on the natural course of the bicuspid aortic valve. However, in order to take any decision about sports eligibility, sports physicians should perform an initial accurate staging of the bicuspid aortic valve, taking into account haemodynamic factors, aortic complications and associated significant cardiovascular anomalies. A strict follow-up, with serial cardiological controls, is mandatory as well as antibiotic prophylaxis for endocarditis, particularly in subjects engaged in contact sports.