Clinical significance of the bicuspid aortic valve

Molecular genetics of aortic valve disease

PURPOSE OF REVIEW

Bicuspid aortic valve is the most common type of cardiac malformation and predisposes to aortic valve calcification, which is the third leading cause of heart disease in adults. These seemingly temporally disparate diseases have been described as having genetic influences but limited data exist on the precise genetic causes in humans. Several advances in the molecular genetics of aortic valve formation and calcification have recently been identified and are described here.

RECENT FINDINGS

A large family with autosomal-dominant aortic valve disease consisting of bicuspid aortic valve and aortic valve calcification was studied using genome-wide linkage analysis. This led to the identification of a nonsense mutation in NOTCH1 in affected individuals. This finding was supported by the discovery of a NOTCH1 frameshift mutation in an unrelated family with similar aortic valve disease, suggesting that NOTCH1 haploinsufficiency was a genetic cause of aortic valve malformations and calcification. The NOTCH signaling pathway was linked to a molecular pathway for aortic valve calcification, as NOTCH1 was found to repress activation of Runx2 - a transcription factor critical for osteoblast cell fate that is up-regulated in calcified human aortic valves.

SUMMARY

The recent genetic and biochemical findings provide novel insights into the molecular and genetic basis for aortic valve dysmorphogenesis and calcification. Future studies focusing on the identification of additional disease-causing and susceptibility genes will aid in the development of prevention strategies. Ultimately, it will be the careful dissection of these molecular pathways that will hopefully lead to novel therapeutic options.

Dilatation of the ascending aorta in paediatric patients with bicuspid aortic valve: frequency, rate of progression and risk factors

OBJECTIVES

To describe the incidence and rate of dilatation of the ascending aorta in children with bicuspid aortic valve (BAV) and to determine factors that predict rapid aortic dilatation.

DESIGN

Retrospective cohort study.

SETTING

Regional tertiary care children's hospital.

PATIENTS

All children aged 0-18 years seen at the authors' institution between 1990 and 2003 with an "isolated" BAV. All patients had had more than one technically adequate echocardiogram, at least six months apart, with concomitant height and weight data.

INTERVENTIONS

Offline echocardiographic measurements of multiple levels of the aortic root were completed for each participant at each serial echocardiogram. These measurements were then compared with expected measurements derived from a normal local control population.

MAIN OUTCOME MEASURES

Rate of change of the ascending aorta size over time, where aortic size is expressed as the number of standard deviations above or below the mean size expected for a given body surface area (z score).

RESULTS

279 echocardiograms spanning a period of from 9 months to 13.3 years were analysed for 88 patients with BAV. The ascending aorta in the BAV group was larger than expected for body surface area at diagnosis and continued to increase in relative size at each of the four subsequent follow-up echocardiograms. Ascending aortic z score increased at an average rate of 0.4/year. A faster rate of increase in z score was predicted by both larger initial aortic valve gradient and non-use of beta blockers.

CONCLUSIONS

Children with BAV are at risk of having a dilated ascending aorta. This risk increases with longer follow up.

Post-stenotic aortic dilatation

Aortic stenosis is the most common valvular heart disease affecting up to 4% of the elderly population. It can be associated with dilatation of the ascending aorta and subsequent dissection. Post-stenotic dilatation is seen in patients with AS and/or aortic regurgitation, patients with a haemodynamically normal bicuspid aortic valve and following aortic valve replacement. Controversy exists as to whether to replace the aortic root and ascending aorta at the time of aortic valve replacement, an operation that potentially carries a higher morbidity and mortality. The aetiology of post-stenotic aortic dilatation remains controversial. It may be due to haemodynamic factors caused by a stenotic valve, involving high velocity and turbulent flow downstream of the stenosis, or due to intrinsic pathology of the aortic wall. This may involve an abnormality in the process of extracellular matrix remodelling in the aortic wall including inadequate synthesis, degradation and transport of extracellular matrix proteins. This article reviews the aetiology, pathology and management of patients with post-stenotic aortic dilatation.

Fate of bicuspid aortic valves in patients undergoing aortic root repair or replacement for aortic root enlargement

OBJECTIVE

To better understand the outcome of the bicuspid aortic valve (BAV) after valve-sparing root replacement, we evaluated BAV function after its preservation at the time of the ascending aorta (AA) repair.

PATIENTS AND METHODS

From January 1, 1994, through March 31, 2002, BAVs were preserved during repair of AA aneurysms in 21 patients (mean +/- SD age, 45+/-12 years; 13 males). We reviewed the clinical and surgical records of these patients for baseline characteristics, operative procedures, and data at latest follow-up.

RESULTS

The primary indication for operation was AA enlargement (median diameter, 55 mm; range, 43-65 mm) in 18 patients and severe aortic regurgitation (AR) in 3 patients. Preoperatively, the BAV exhibited mild or moderate stenosis in 5 patients (mean gradient, 25 mm Hg; range, 19-34 mm Hg), moderate AR in 2, and severe AR in 3. Aortic valve repair was performed in 11 patients. Seventeen patients had excision and graft replacement of the enlarged AA, and 4 patients had primary AA repair. There were no perioperative deaths. Moderate or severe AR was relieved in all patients early postoperatively and during follow-up (median, 2.5 years; maximum, 7.6 years). One patient required aortic valve replacement at 4.8 years for AR. An additional patient had recurrent, severe AR but was asymptomatic and has not undergone reoperation.

CONCLUSION

Repair of diseased BAVs or preservation of functionally normal BAVs during surgery for AA aneurysms has a low perioperative risk, and early results are encouraging. Additional observation is necessary to determine whether this strategy has real advantages over early aortic valve replacement.

Acute aortic dissection

Acute aortic dissection is an uncommon but lethal cause of acute chest, back, and abdominal pain. Establishing a timely diagnosis is paramount, as mortality from acute aortic dissection rises by the hour. Physical findings are protean and may include acute aortic valve insufficiency, peripheral pulse deficits, a variety of neurologic deficits, or end-organ ischemia. The keys to establishing a timely diagnosis are maintaining a high index of suspicion and quickly obtaining a diagnostic study. CT angiography, magnetic resonance imaging, transesophageal echocardiography, and, to a lesser extent, aortography are all highly accurate imaging modalities. The choice of study should be driven by the clinical stability of the patient, the information required and the resources available at presentation. Proximal dissections are surgical emergencies, but distal dissections are generally treated medically. Endovascular stents are gaining favor for use in the repair of both acute and chronic distal dissections. Long-term outcome data for endovascular stenting are still limited, and it remains unclear when stenting should be favored over surgery or medical therapy.

Planimetric Assessment of Anatomic Valve Area Overestimates Effective Orifice Area in Bicuspid Aortic Stenosis

BACKGROUND

Although the continuity equation remains the noninvasive standard, planimetry using transesophageal echocardiography is often used to assess valve area for patients with aortic stenosis (AS). Not uncommonly, however, anatomic valve area (AVAA) obtained by planimetry overestimates continuity-derived effective valve area (AVAE) in bicuspid AS.

METHODS

Transthoracic Doppler and transesophageal echocardiography were performed to obtain AVAE and AVAA in 31 patients with bicuspid AS (age 61 +/- 11 years) and 22 patients with degenerative tricuspid AS (age 71 +/- 13 years). Aortic root and left ventricular outflow tract dimensions and the directional angle of the stenotic jet were assessed in all patients. Using these data, a computational fluid dynamics model was constructed to test the effect of these variables in determining the relationship between AVAE and AVAA.

RESULTS

For patients with tricuspid AS, the correlation between AVAA (1.15 +/- 0.36 cm2) and AVAE (1.13 +/- 0.46 cm2) was excellent (r = 0.91, P < .001, Delta = 0.02 +/- 0.21 cm2). However, AVAA was significantly larger (1.19 +/- 0.35 cm2) than AVAE (0.89 +/- 0.29 cm2) in the bicuspid AS group (r = 0.71, P < .001, Delta = 0.29 +/- 0.25 cm2). Computer simulation demonstrated that the observed discrepancy related to jet eccentricity.

CONCLUSION

For a given anatomic orifice, functional severity tends to be greater in bicuspid AS than in tricuspid AS. This appears to be primarily related to greater jet eccentricity and less pressure recovery.

Different patterns of extracellular matrix protein expression in the convexity and the concavity of the dilated aorta with bicuspid aortic valve: preliminary results

OBJECTIVE

This study aimed to assess extracellular matrix protein expression patterns at the convexity (right anterolateral wall) and the concavity of the dilated ascending aorta in patients with bicuspid aortic valve disease.

METHODS

Aortic wall specimens were retrieved from the convexity and the concavity in 27 bicuspid aortic valve patients (12 with stenosis and 15 with regurgitation) and 6 heart donors (controls). Morphometry, immunohistochemistry, Western blot, and polymerase chain reaction were performed, focusing on matrix proteins involved in vascular remodeling.

RESULTS

Type I and III collagens were significantly decreased in bicuspid-associated dilated aortas versus controls (P < .001), particularly at the convexity (P < .05 vs concavity). Expression of messenger RNA for collagens was lower than normal only in the regurgitant subgroup. At immunohistochemistry, proteins whose overproduction has been demonstrated in response to abnormal wall stress, such as tenascin and fibronectin, were more expressed in the convexity than in the concavity, especially in the stenosis subgroup. Tenascin, which is produced by smooth muscle cells in the synthetic phenotype, was nearly undetectable in controls. Fewer smooth muscle cells (stenosis, P = .017; regurgitation, P = .008) and more severe elastic fiber fragmentation (P = .029 and P < .001) were observed in the convexity versus the concavity.

CONCLUSIONS

In bicuspid-associated aortic dilations, an asymmetric pattern of matrix protein expression was found that was consistent with the asymmetry in wall-stress distribution reported previously. Differences exist between patients with stenosis and those with regurgitation in terms of protein expression and content in the aortic wall. Further studies could clarify the relations between these findings and the pathogenesis of aortic dilatation in bicuspid aortic valve patients.

Usefulness of MRI in the follow-up of patients with repaired aortic coarctation and bicuspid aortic valve

BACKGROUND

The long-term outcome of repaired aortic coarctation may be complicated by dilatation of the ascending aorta notably in patients with bicuspid aortic valve. Magnetic resonance imaging was used to compare the size of the ascending aorta in patients with bicuspid or tricuspid aortic valve.

METHODS

In 50 patients with a repair of aortic coarctation, the size of the ascending aorta was measured in a bicuspid aortic valve group (n=11) and a tricuspid aortic valve group (n=39). The aortic diameter was measured at the level of the sinus of Valsalva and at the widest part of the ascending aorta using magnetic resonance imaging.

RESULTS

The mean age of patients at surgical repair was respectively 2.2+/-3.3 years for the bicuspid aortic valve group and 2.5+/-3.5 years for the tricuspid aortic valve group (p=NS) and the mean age at the time of the magnetic resonance imaging was 10.2+/-4.7 years and 9.3+/-5.9 years (p=NS) respectively. A significant difference in the aortic diameter was found between the bicuspid aortic valve group and the tricuspid aortic group both at the level of sinus of Valsalva (34.8+/-8.2 mm, 19.5+/-4.4 mm, respectively, p<0.01) and at the level of the ascending aorta (36.8+/-7.2 mm, 16.9+/-3.4 mm, respectively, p<0.01).

CONCLUSIONS

The occurrence of ascending aortic dilatation is significantly associated with the presence of a bicuspid aortic valve. This requires long-term follow-up, which can be effectively performed by magnetic resonance imaging.

Ross Procedure in a Quadricuspid Aortic Valve

A quadricuspid aortic valve is a rare congenital cardiovascular abnormality, and when present, it is associated with aortic valve regurgitation. If aortic valve replacement is required, mechanical or biological prostheses are used. We report the case of a patient with a severely regurgitant quadricuspid aortic valve in whom a Ross procedure was performed.

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.

Echocardiographic and hemodynamic characteristics of reconstructed bicuspid aortic valves at rest and exercise

Repair of diseased bicuspid aortic valves has gained increasing interest as an alternative to conventional valve replacement. Hemodynamic data at exercise have not been reported before. The aim of this study was to investigate the clinical and echocardiographic status of patients after bicuspid aortic valve repair at rest and exercise. Between 03/94 and 09/02 a reconstruction of an incompetent bicuspid aortic valve was performed in 25 patients (mean age 35+/-12.1 years, group A, mean insufficiency 2.8 preoperatively). Patients were investigated clinically and echocardiographically after 2.1+/-2.4 (0.1-8.9) years at rest and exercise and compared to 20 controls (group B). Clinical followup was complete. There were no deaths, reoperations, thromboembolic or bleeding complications. At last examination 21 patients were in NYHA class I, n=4 in NYHA class II and mean aortic valve insufficiency (AI) was 1.0 with one patient having an AI>II degrees. Maximum and mean pressure gradient (dPmax/mean) across the aortic valve at rest were 14+/-5.5/7+/-2.6 mmHg for patients of group A and 7+/-2.5/3.6+/-1.1 mmHg in group B. Mean AVA at rest was 2.6+/-0.8 (group A) vs 2.9+/-0.6 cm(2) (group B, p=0.025), valvular resistance 13.4+/-4.8 (group A) vs 13.6+/-2.9 dyn x s x cm(-5) (group B, p>0.05). All individuals were stressed up to 100 W (dPmax/mean 21+/-6.8/11+/-3.6, group A vs 11+/-2.9/6+/-1.3 mmHg, group B). 56% of group A and 85% of group B could be stressed up to 175 W with dPmax/mean 24.5+/-8.3/12+/-4.2 and 16+/-3.6/8+/-1.4 mmHg, respectively (p<0. 01). Heart rate and blood pressure behavior were comparable. Left ventricular mass regression (preoperatively 369.3+/-76.4 vs 277.3+/-80.7 g at last examination, p<0.01) was significant in group A but did not reach normal values (group B, 227.8+/-71.1; p<0.01). Bicuspid aortic valve reconstruction reduces left ventricular volume load significantly. Although residual mild subclinical obstruction and incompetence were observed, the behavior of hemodynamics at exercise was comparable to controls. The clinical relevance of these findings in long term follow-up has to be evaluated.

Inheritance analysis of congenital left ventricular outflow tract obstruction malformations: Segregation, multiplex relative risk, and heritability

The left ventricular outflow tract (LVOTO) malformations, aortic valve stenosis (AVS), coarctation of the aorta (COA), and hypoplastic left heart (HLH) constitute a mechanistically defined subgroup of congenital heart defects that have substantial evidence for a genetic component. Evidence from echocardiography studies has shown that bicuspid aortic valve (BAV) is found frequently in relatives of children with LVOTO defects. However, formal inheritance analysis has not been performed. We ascertained 124 families by an index case with AVS, COA, or HLH. A total of 413 relatives were enrolled in the study, of which 351 had detailed echocardiography exams for structural heart defects and measurements of a variety of aortic arch, left ventricle, and valve structures. LVOTO malformations were noted in 30 relatives (18 BAV, 5 HLH, 3 COA, and 3 AVS), along with significant congenital heart defects (CHD) in 2 others (32/413; 7.7%). Relative risk for first-degree relatives in this group was 36.9, with a heritability of 0.71-0.90. Formal segregation analysis suggests that one or more minor loci with rare dominant alleles may be operative in a subset of families. Multiplex relative risk analysis, which estimates number of loci, had the highest maximum likelihood score in a model with 2 loci (range of 1-6 in the lod-1 support interval). Heritability of several aortic arch measurements and aortic valve was significant. These data support a complex but most likely oligogenic pattern of inheritance. A combination of linkage and association study designs is likely to enable LVOTO risk gene identification. This data can also provide families with important information for screening asymptomatic relatives for potentially harmful cardiac defects.

Management of the Valve and Ascending Aorta in Adults with Bicuspid Aortic Valve Disease

Bicuspid aortic valve (BAV) disease is the most common congenital cardiac malformation, being present in 1% to 2% of the population. It is heritable and is three to four times more likely to occur in men. The pathogenesis of BAV disease is unknown. Bicuspid valves progress to aortic stenosis or insufficiency in the majority of patients. BAV disease is associated with several anomalies of the aorta including coarctation, aneurysm formation, and dissection. Several lines of evidence suggest that aortic complications are caused by the same underlying factor that causes BAV disease, rather than being a consequence of turbulent blood flow through a stenotic valve. Several different surgical options exist for patients with BAV disease depending on the age of presentation and the size and appearance of the aorta. We herein describe our surgical management of the aortic valve and ascending aorta in patients with BAV disease.

Late complications in patients after repair of aortic coarctation: implications for management

Survival of patients with aortic coarctation has dramatically improved after surgical repair became available and the number of patients who were operated and reach adulthood is steadily increasing. However, life expectancy is still not as normal as in unaffected peers. Cardiovascular complications are frequent and require indefinite follow-up. Concern falls chiefly in seven categories: recoarctation, aortic aneurysm formation or aortic dissection, coexisting bicuspid aortic valve, endocarditis, premature coronary atherosclerosis, cerebrovascular accidents and systemic hypertension. In this review, these complications, with particular reference to late hypertension, are discussed and strategies for the clinical management of post-coarctectomy patients are described.

Feasibility of Valve Repair for Regurgitant Bicuspid Aortic Valves—An Echocardiographic Study

BACKGROUND

There is increasing interest in the role of valve repair for patients with isolated severe aortic regurgitation. Those with bicuspid aortic valves are suggested as most suitable for repair. Morphologic features of these valves that suggest feasibility of repair are not well defined.

METHODS

Perioperative echocardiograms on 132 consecutive patients (mean age 42 +/- 12 years; 94% male), with bicuspid valves and isolated aortic regurgitation undergoing surgery at our institution were reviewed. Seventy-five patients (57%) underwent successful valve repair. Repair was attempted but unsuccessful for another 8 patients (6 intraoperatively and 2 before discharge).

RESULTS

Cusp prolapse was the most common primary mechanism of regurgitation (88 patients [67%]), with 81 patients having primarily eccentrically directed regurgitation. Echocardiographic examination of 72 (55%) had evidence of cusp thickening with 40 (30%) having cusp calcification. By multivariate analysis, an eccentric regurgitant jet direction (odds ratio = 14.3; 95% confidence interval [CI] = 3.4 to 59.6), lack of cusp thickening (odds ratio = 5.9 [1.7 to 20]), lack of cusp calcification (odds ratio = 4.2; [1.1 to 16.7]) and the absence of commissural thickening (odds ratio = 4.8 [1.3 to 16.7]) were independently associated with a greater likelihood of successful valve repair. Greater cusp thickening was the only factor associated with attempted but failed repair.

CONCLUSIONS

Successful repair of regurgitant bicuspid aortic valves was more feasible for those patients with eccentric regurgitant jets, those without cusp or commissural thickening or cusp calcification. Recognition of these features may enhance patient selection and improve procedural outcomes with aortic valve repair.

Aortic Valve-Sparing Procedure With Cusp Elongation and Free Edge Reinforcement for Bicuspid Aortic Valve

Aortic valve-sparing procedures demonstrate excellent valvular function at midterm. Recently authors have reported acceptable early results with aortic valve-sparing procedures on patients with regurgitant bicuspid valves. We report the case of a novel procedure to preserve bicuspid valves with a calcified raphe and root dilatation. This procedure includes raphe excision, pericardial patch elongation, free edge leaflet reinforcement, and a root reimplantation valve-sparing procedure.

Aortic valve morphology definition with transthoracic combined with transesophageal echocardiography in a population with high prevalence of bicuspid aortic valve

OBJECTIVE

To assess the utility of transthoracic echocardiography (TTE) with second harmonic combined with transesophageal echocardiography (TEE) in defining aortic valve morphology in a subset of patients with a high prevalence of bicuspid aortic valve.

METHODS AND MATERIALS

Patients (n = 174) with dilated aortic root were consecutively evaluated using, initially, TTE. The aortic valve structure was assigned as tricuspid, bicuspid or undefined. In those assigned as bicuspid or undefined, TEE was performed. Other factors that could affect valve morphology assignment were recorded and evaluated in multivariate analysis.

RESULTS

TTE was able to characterise 89% of the tricuspid valves and 56% of the bicuspid. Bicuspid structure was the only variable that, in the multivariate analysis, was related to the inability to definitively assign aortic valve morphology (OR = 0.13). TEE was performed in 59 patients and the morphology was definitively assigned in 56 of them (95%). TEE diagnosed 15 bicuspid valves in addition to confirming the 17 identified by TTE. Overall, using TTE combined with TEE we were able to correctly assign valvular morphology in 98% of patients.

CONCLUSION

In a subset of patients with a high prevalence of bicuspid aortic valve, combination of TTE and TEE should be considered to define aortic valve morphology. TEE identifies an important number of patients with BAV.

Matrix metalloproteinases in ascending aortic aneurysms: bicuspid versus trileaflet aortic valves

BACKGROUND

Abnormal matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) expression contributes to the development of abdominal aortic aneurysms. Recent data suggest that MMP-2 and MMP-9 may also play a role in thoracic aortic disease. We sought to determine (1) whether ascending aortic aneurysms are associated with increased MMP expression and (2) whether aortic inflammation and MMP expression differ between patients with congenital bicuspid aortic valves (BAVs) and those with trileaflet aortic valves (TAVs).

MATERIALS AND METHODS

Samples of ascending aortic aneurysms were obtained from 29 patients; 14 patients had BAVs and 15 had TAVs. Control ascending aorta was obtained from 14 organ donors or heart transplant recipients. Aortic histology and immunohistochemistry were performed to evaluate elastin degradation, inflammatory changes, and MMP-2 and MMP-9 expression. Aortic levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured using ELISA.

RESULTS

Aneurysms in the TAV patients exhibited marked inflammation, high CD68 expression, diminished elastin content, increased MMP-9 expression, and normal MMP-2 levels. In contrast, BAV aneurysms were characterized by a relative lack of inflammation, preservation of elastin content, normal MMP-9 levels, and elevated MMP-2 expression. TIMP-1 and TIMP-2 levels were not significantly different among the three groups.

CONCLUSIONS

Ascending aortic aneurysms exhibited increased MMP expression. The pattern of MMP expression and the degree of inflammation, however, differed between aneurysms associated with BAVs and those with TAVs. Variations in the molecular mechanisms underlying different types of thoracic aortic aneurysms warrant further investigation.

Morphology of bicuspid aortic valve in children and adolescents

OBJECTIVES

The aim of this study was to determine the relationship between aortic valve morphology and valve dysfunction.

BACKGROUND

The morphology of the bicuspid or bicommissural aortic valve (BAV) may predict the severity of valve dysfunction. Therefore, we assessed the relationship between BAV, aortic coarctation, and the degree of valve pathology in children.

METHODS

A retrospective review of 1,135 patients with BAV who were identified between 1986 and 1999 was performed. Patients younger than 18 years of age with BAV that was identifiable via echocardiography were included. The most recent or last study of each patient before intervention or endocarditis was reviewed. Mild stenosis was defined as a valve gradient > or =2 m/s, moderate or greater aortic stenosis as > or =3.5 m/s. Aortic regurgitation was quantified using standard criteria.

RESULTS

Median age was 3 years (range, 1 day to 17.9 years), and 67% of the patients were male. Right-coronary and left-coronary leaflet fusion were the most common types of BAV (70%). Aortic stenosis that was moderate or greater was observed most often in patients with right-coronary and non-coronary leaflet fusion (odds ratio 2.4, 95% confidence interval 1.6 to 3.6; p < or = 0.001). Similarly, right-coronary and non-coronary leaflet fusion was more often associated with moderate aortic regurgitation or greater (odds ratio 2.4, 95% confidence interval 1.2 to 4.7; p = 0.01). The majority of patients with aortic coarctation had fusion of the right-coronary and left-coronary leaflets (89%), and aortic coarctation was associated with lesser degrees of valve stenosis or regurgitation.

CONCLUSIONS

Analysis of BAV morphology is of clinical and prognostic relevance. Fusion of the right-coronary and non-coronary leaflets was associated with more significant valve pathology, whereas fusion of the right-coronary and left-coronary leaflets was associated overwhelmingly with aortic coarctation and less aortic valve pathology.

Reconstructed Bicuspid Aortic Valve after 10 Years: Clinical and Echocardiographic Follow-up

BACKGROUND

Sixteen patients (mean age, 30.9 +/- 12.9 years; range, 9-79 years) with incompetent bicuspid aortic valves underwent valve-sparing correction between 1992 and 1995.

METHODS

All patients underwent triangular resection of the enlarged leaflet. In addition, 13 patients underwent commissuroplasty. In 3 patients leaflet perforations were corrected with glutaraldehyde-fixed autologous pericardial patch. All patients underwent annual echocardiographic and clinical examinations at our institution.

RESULTS

During follow-up 1 patient died of heart failure, and 3 patients underwent reoperations because of valve incompetence or dilatation of the sinus. Two patients underwent reoperation perioperatively. At long-term follow-up (mean, 10.06 +/- 1.01 years) the remaining 10 patients were in New York Heart Association class I. No patient was receiving anticoagulation, and no thromboembolic, bleeding, or endocarditis events were observed in 107.2 cumulative patientyears of follow-up. Mean grade of regurgitation was 0.7 +/- 0.5; mean aortic flow velocity was 2.29 +/- 0.47 m/s. Optimal valvular function led to normal ventricular diameters (left ventricular end systolic diameter, 39.2 +/- 4.3 mm; left ventricular end diastolic diameter, 56.2 +/- 5.9 mm) and normal ventricular function (fractional shortening, 31.5% +/- 0.1%). The dimensions of the aortic root were stable from 1-year to late followup (mean aortic annulus, 27.1 +/- 6.8 mm; sinus of Valsalva, 33.0 +/- 7.1 mm; sinotubular junction, 34.1 +/- 7.7 mm; ascending aorta, 31.6 +/- 7.4 mm).

CONCLUSION

In contrast to early follow-up results of 5 reoperations, clinical and echocardiographic results were excellent for 10 patients who had undergone reconstruction of bicuspid incompetent aortic valves, and the patients were in stable condition after 10 years. However, the mode of early failure is unknown. Reconstruction of bicuspid valves is possible in selected patients.

Bicuspid aortic valve is heritable

OBJECTIVES

Previous studies have established familial clustering of bicuspid aortic valve (BAV), presumably indicating genetic inheritance. Our objective was to statistically test whether the segregation pattern of BAV is consistent with genetic inheritance and to obtain an estimate of the size of the genetic effect (heritability).

BACKGROUND

Bicuspid aortic valve occurs in 1% of the population, making it the most common cardiovascular malformation (CVM). Bicuspid aortic valve is frequently an antecedent to aortic valve stenosis or insufficiency and is often associated with other CVMs, including aortic root dilation. The genetic and developmental significance of these findings remains obscure.

METHODS

In 50 probands with BAV, we obtained a three-generation family history and echocardiograms on first-degree relatives. Heritability (h2) of BAV and BAV and/or other CVMs were estimated using maximum-likelihood-based variance decomposition extended to dichotomous traits implemented in the computer package Sequential Oligogenic Linkage Analysis Routines (SOLAR, San Antonio, Texas).

RESULTS

A total of 309 probands and relatives participated. Bicuspid aortic valve was identified in 74 individuals (prevalence = 24%). A total of 97 individuals had BAV and/or other CVM (prevalence = 31%), including aortic coarctation, ventricular or atrial septal defect, abnormal mitral valve, aortic root dilation, or hypoplastic left heart syndrome. The heritability (h2) of BAV and BAV and/or other CVMs were 89% and 75%, respectively.

CONCLUSIONS

The high heritability of BAV suggests that in this study population BAV determination is almost entirely genetic. The heritability of BAV plus other cardiovascular anomalies suggests that valve malformation can be primary to defective valvulogenesis or secondary to other elements of cardiogenesis.

Echocardiographic evaluation of asymptomatic parental and sibling cardiovascular anomalies associated with congenital left ventricular outflow tract lesions

OBJECTIVE

Left ventricular outflow tract obstructive (LVOTO) malformations are a leading cause of infant mortality from birth defects. Genetic mechanisms are likely, and there may be a higher rate of asymptomatic LVOTO anomalies in relatives of affected children. This study sought to define the incidence of cardiac anomalies in first-degree relatives of children with congenital aortic valve stenosis (AVS), coarctation of the aorta (CoA), and hypoplastic left heart syndrome (HLHS).

METHODS

A total of 113 probands with a nonsyndromic LVOTO malformation of AVS (n = 25), BAV (n = 3), CoA (n = 52), HLHS (n = 30), and aortic hypoplasia with mitral valve atresia (n = 2) were ascertained through chart review or enrolled at the time of diagnosis. Echocardiography was performed on 282 asymptomatic first-degree relatives.

RESULTS

Four studies had poor acoustic windows, leaving 278 studies for analysis. BAV were found in 13 (4.68%) first-degree relatives. The relative risk of BAV in the relatives was 5.05 (95% confidence interval: 2.2-11.7), and the broad sense heritability was 0.49, based on a general population frequency of 0.9%. BAV was more common in multiplex families compared with sporadic cases. An additional 32 relatives had anomalies of the aorta, aortic valve, left ventricle, or mitral valve.

CONCLUSIONS

The presence of an LVOTO lesion greatly increases the risk of identifying BAV in a parent or sibling, providing additional support for a complex genetic cause. The parents and siblings of affected patients should be screened by echocardiography as the presence of an asymptomatic BAV may carry a significant long-term health risk.

Influence of structural geometry on the severity of bicuspid aortic stenosis

Doppler-derived gradients may overestimate total pressure loss in degenerative and prosthetic aortic valve stenosis (AS) due to unaccounted pressure recovery distal to the orifice. However, in congenitally bicuspid valves, jet eccentricity may result in a higher anatomic-to-effective orifice contraction ratio, resulting in an increased pressure loss at the valve and a reduced pressure recovery distal to the orifice leading to greater functional severity. The objective of our study was to determine the impact of local geometry on the total versus Doppler-derived pressure loss and therefore the assessed severity of the stenosis in bicuspid valves. On the basis of clinically obtained measurements, two- and three-dimensional computer simulations were created with various local geometries by altering the diameters of the left ventricular outflow tract (LVOT; 1.8–3.0 cm), orifice diameter (OD; 0.8–1.6 cm), and aortic root diameter (AR; 3.0–5.4 cm). Jet eccentricity was altered in the models from 0 to 25°. Simulations were performed under steady-flow conditions. Axisymmetric simulations indicate that the overall differences in pressure recovery were minor for variations in LVOT diameter (<3%). However, both OD and AR had a significant impact on pressure recovery (6–20%), with greatest recovery being the larger OD and the smaller recovery being the AR. In addition, three-dimensional data illustrate a greater pressure loss for eccentric jets with the same orifice area, thus increasing functional severity. In conclusion, jet eccentricity results in greater pressure loss in bicuspid valve AS due to reduced effective orifice area. Functional severity may also be enhanced by larger aortic roots, commonly occurring in these patients, leading to reduced pressure recovery. Thus, for the same anatomic orifice area, functional severity is greater in bicuspid than in degenerative tricuspid AS.

Endocarditis with ruptured cerebral aneurysm caused by Cardiobacterium valvarum sp. nov

A fastidious gram-negative bacterium was isolated from the blood of a 37-year-old man who had insidious endocarditis with a sudden rupture of a cerebral aneurysm. Characterization of the organism through phylogenetic and phenotypic analyses revealed a novel species of Cardiobacterium, for which the name Cardiobacterium valvarum sp. nov. is proposed. C. valvarum will supplement the current sole species Cardiobacterium hominis, a known cause of endocarditis. Surgeries and antibiotic treatment cured the patient's infection and associated complications. During cardiac surgery, a congenital bicuspid aortic valve was found to be the predisposing factor for his endocarditis.

Is a bicuspid aortic valve a risk factor for adverse outcome after an autograft procedure?

BACKGROUND

Recently, bicuspid aortic valve disease is posed to be a possible risk factor for dilatation of the pulmonary autograft.

METHODS

Analysis of all 123 patients in our prospective cohort with their native aortic valve in situ at the autograft procedure.

RESULTS

The bicuspid aortic valve group (n = 81) had more males (p = 0.05), prior cardiac surgery (p = 0.02), prior aortic valve balloon dilatation (p = 0.01), aortic stenosis (p = 0.03), and less deterioration of left ventricular function (p = 0.02) than the tricuspid group (n = 42). Hospital mortality occurred in 3 patients (bicuspid 2, tricuspid 1). The follow-up was 99% complete (median, 5.3 years; SD, 3.5; range, 0.1 to 13.4) with a total of 674 patient years. During follow-up 4 patients died (bicuspid 2, tricuspid 2). Overall survival was 95% (95% confidence interval [CI], 89% to 98%) at 5 and 10 years. Seven patients required reoperation for autograft failure, all structural. Freedom from autograft reintervention was 97% (95% CI, 92% to 100%) at 5 years and 89% (95% CI, 79% to 98%) at 10 years. There were no differences in outcome between the groups. Four patients required reoperation for allograft failure, all structural. Freedom from allograft reoperation was 99% (95% CI, 97% to 100%) at 5 years and 91% (95% CI, 82% to 100%) at 10 years. There was no difference between the groups.

CONCLUSIONS

An autograft procedure in patients with a bicuspid aortic valve is justified. Bicuspid aortic valve disease is not a contraindication for an autograft procedure. Patients with a bicuspid aortic valve will meet the limitations of the autograft procedure in the same frequency as the overall autograft population.

Characterizing the young patient with aortic dissection: results from the International Registry of Aortic Dissection (IRAD)

OBJECTIVES

The goal of this study was to better characterize the young patient with aortic dissection (AoD).

BACKGROUND

Aortic dissection is unusual in young patients, and frequently associated with unusual presentations.

METHODS

Data were collected on 951 patients diagnosed with AoD between January 1996 and November 2001. Two categories of patients, <40 years and >or=40 years, were compared using chi-square cross tabulations for categorical and Student t test for continuous data.

RESULTS

Sixty-eight patients (7%) with AoD were <40 years of age. Compared with patients >or=40 years, younger patients were less likely to have a prior history of hypertension (p < 0.05); however, younger patients were more likely to have Marfan syndrome, bicuspid aortic valve, and prior aortic surgery (all, p < 0.05). Clinical presentations in the two age groups were similar; however, younger patients were less likely to be hypertensive (25% vs. 45%, p = 0.003). The proximal aortas of young AoD patients were larger (all, p < 0.05) compared with older patients. These differences in aortic size between age groups were not entirely related to Marfan syndrome. Mortality among young patients was similar to patients >or=40 years of age (22% vs. 24%, p = NS), irrespective of the site of dissection.

CONCLUSIONS

Compared with older patients with AoD, young patients have unique risk factors for dissection: Marfan syndrome, bicuspid aortic valves, and larger aortic dimensions. Surprisingly, the mortality risk for young AoD patients is not lower than older AoD patients.

An echocardiographic survey of primary school children for bicuspid aortic valve

Primary school students (817 apparently healthy 10-year olds) were screened by transthoracic 2-dimensional echocardiography to assess for the prevalence of bicuspid aortic valve. Bicuspid aortic valve was found in 0.5% of cases, with a higher prevalence in males than females (0.75% vs 0.24%), and was significantly associated with aortic root enlargement compared with children who had tricuspid aortic valves.

Failure to prevent progressive dilation of ascending aorta by aortic valve replacement in patients with bicuspid aortic valve: comparison with tricuspid aortic valve

BACKGROUND

Patients with bicuspid aortic valve (BAV) have been frequently complicated with ascending aortic dilation possibly because of hemodynamic burdens by aortic stenosis (AS) or regurgitation (AR) or congenital fragility of the aortic wall.

METHODS AND RESULTS

To clarify if the aortic dilation could be prevented by aortic valve replacement (AVR) in BAV patients, we studied 13 BAV (8 AR dominant, 5 AS dominant) and 14 tricuspid aortic valve (TAV) patients (7 AR, 7 AS) by echocardiography before and after AVR (9.7+/-4.8 years). We also studied 18 BAV (11 AR, 7 AS) without AVR. Diameters of the sinuses of Valsalva, sinotubular junction and the proximal aorta were measured. The annual dilation rate was calculated by dividing changes of diameters during the follow-up period by the body surface area and the observation interval. We found that aortic dilation in BAV patients tended to be faster than that in TAV patients, although a significant difference was found only at the proximal aorta (0.18+/-0.08 versus -0.08+/-0.08 mm/(m2/year), P=0.03). BAV patients with and without AVR showed similar progressive dilation. AR dominant group showed tendency of more progressive dilation than AS dominant group in BAV, although it did not reach statistical significance. TAV patients did not show further aortic dilation after AVR.

CONCLUSIONS

AVR could not prevent progressive aortic dilation in BAV. Since the aorta did not dilate in TAV, progressive aortic dilation in BAV seems mainly due to the fragility of the aortic wall rather than hemodynamic factors.

Stability of ascending aortic dilatation following aortic valve replacement

BACKGROUND

Replacement of the ascending aorta (Asc Ao) at the time of aortic valve replacement (AVR) is controversial because the risk of progressive dilatation following valve replacement is uncertain. Our aim was to determine the natural history of ascending aortic dilatation following AVR.

METHODS AND RESULTS

We studied 185 patients undergoing AVR at our institution between 1992 and 1999. Clinical and echocardiographic data were obtained by merging our institutional echocardiographic database with the DHMC component of the Northern New England Cardiovascular Disease Study Group database. Baseline Asc Ao measurements obtained from intraoperative transesophageal echocardiograms or early (<8 weeks) postoperative transthoracic echocardiograms were compared with late follow-up measurements (mean follow-up 30.0+/-23.4 months). During follow-up, there was no increase in the mean Asc Ao diameter (3.6+/-0.6 cm versus 3.6+/-0.6 cm, p=NS). Progressive aortic dilatation, defined as an increase in diameter >0.3 cm, occurred in 27/185 patients (15%). Baseline Asc Ao dilatation (>or=3.5 cm) was present in 107/185 patients (58%). In this subset of patients, there was no increase in mean Asc Ao diameter (4.0+/-0.4 versus 3.9+/-0.6 cm, p=NS) and progressive aortic dilatation occurred in only 10 patients (9.3%). No patients with baseline aortic dilatation (range, 3.5 to 5.3 cm) dilated beyond 5.5 cm on follow-up (range, 2.4 to 5.5 cm). There were no clinical or valvular characteristics that predicted progressive Asc Ao dilatation.

CONCLUSIONS

An increase in Asc Ao dilatation occurs infrequently following AVR and therefore, argues against routine Asc Ao replacement at the time of AVR.

Aortic valve and aortic arch pathology after coarctation repair

OBJECTIVE

To investigate the incidence of clinical problems related to a bicuspid valve (aortic stenosis and regurgitation) and the incidence of ascending aorta and aortic arch pathology in combination with coarctation repair.

PATIENTS

124 adult patients after surgical correction of aortic coarctation were studied. The incidence of aortic valve, ascending aorta, and aortic arch pathology was determined using echocardiography and magnetic resonance imaging. The median age at coarctation repair was 9 years and at last follow up 28 years.

RESULTS

Three patients died from aorta pathology. Aortic valve disease was found in 63% of the patients, requiring an intervention in 22%, at a median of 13 years after coarctation repair. Ascending aorta dilatation was observed in 28% and aortic arch abnormalities in 23%, among whom kinking of the aortic arch was found in 12%. Antihypertensive medication was used in 24%. In the patients with hypertension the age at operation and age at follow up were significantly higher (p = 0.0001 and p < 0.0001, respectively).

CONCLUSION

In addition to the well known problems of hypertension and recoarctation, aortic valve and aortic arch pathology are commonly encountered in patients with previous coarctation repair. Aortic abnormalities may predispose to dilatation and dissection, thus necessitating careful lifelong attention in all patients with coarctation.

A syndrome of spontaneous cerebral and cervical artery dissections with angiolipomatosis. Report of two cases

A primary or systemic arteriopathy is frequently suspected in patients with spontaneous cerebral or cervical artery dissections. The authors report on two patients with such dissections accompanied by angiolipomatosis, a previously unreported association, and propose a common developmental defect in these patients. A 50-year-old man with subcutaneous angiolipomatosis developed painful monocular blindness. Angiography studies revealed a spontaneous extracranial internal carotid artery (ICA) dissection and an ipsilateral fusiform intracranial ICA aneurysm. The ICA dissection was treated with aspirin, and after 6 months a craniotomy was performed. The aneurysm was found to be fusiform; it involved the entire supraclinoid portion of the ICA, and was wrapped with cotton. A 49-year-old man with a congenitally bicuspid aortic valve and subcutaneous angiolipomatosis developed posterior neck pain. Magnetic resonance imaging and angiography demonstrated a fusiform distal vertebral artery aneurysm. A craniotomy was performed and the aneurysm was found to incorporate the posterior inferior cerebellar artery as well as a perforating artery: the lesion was wrapped cotton. The tunica media of the arteries of the head and neck as well as the aortic valvular cusps are derived from neural crest cells, and angiolipomatosis has been associated with tumors of neural crest derivation. These associations indicate that a neural crest disorder may be the underlying abnormality in these patients.

Anatomic three-dimensional echocardiographic correlation of bicuspid aortic valve

This study was undertaken to verify the echocardiographic characteristics of bicuspid aortic valve (AV) using 3-dimensional transesophageal echocardiography by comparing the findings with anatomic examination of autopsy specimens from carriers of this condition. Three-dimensional reconstructions of transesophageal echocardiograms were performed on 14 patients with bicuspid AV, and 20 autopsy specimens of bicuspid AVs were analyzed. Echocardiographic images and autopsy material were correlated. Two variants of bicuspid aorta were identified. In group I the AV had 2 leaflets. This group included 9 (9/14) 3-dimensional echocardiographic studies and 13 (13/20) necropsies. In group II 3 sigmoid leaflets had originally developed and 2 underwent dysplastic fusion, resulting in functionally bicuspid valves. Five (5/14) echocardiographic studies and 7 (7/20) anatomic specimens fell into this category. There was a clear correspondence between anatomic and echocardiographic findings, which leads to the conclusion that 3-dimensional echocardiography is a technique that reliably defines the morphological details of bicuspid AV with the precision of anatomopathologic examination.

T lymphocyte infiltration in non-rheumatic aortic stenosis: a comparative descriptive study between tricuspid and bicuspid aortic valves

BACKGROUND

The two most common causes of aortic stenosis are primary "degenerative" calcification of tricuspid aortic valves and secondary calcification of congenital bicuspid valves. T lymphocyte infiltration occurs in stenotic tricuspid aortic valves, indicating an inflammatory component, but it has not been shown whether it also occurs in stenotic bicuspid valves.

OBJECTIVE

To compare non-rheumatic tricuspid and bicuspid stenotic aortic valves for the presence and distribution of T lymphocytes.

SETTING

University hospital.

PATIENTS AND DESIGN

Valve specimens were obtained from 29 patients (15 women, 14 men, mean age 69 years (range 52-81 years)), referred to the hospital for aortic valve replacement because of symptomatic aortic valve stenosis. There were 17 tricuspid valves (from 10 women and seven men, mean age 71 years) and 12 bicuspid valves (from five women and seven men, mean age 67 years). To identify mononuclear inflammatory cells, sections were stained with antibodies for CD3 (pan-T cell antigen, Dako 1:400) and then graded histologically according to the degree of T cell infiltrate.

RESULTS

T lymphocyte infiltration was present in both tricuspid and bicuspid stenotic aortic valves, without any significant differences in extent or localisation.

CONCLUSIONS

Stenotic bicuspid aortic valves show the same degree of T lymphocyte infiltration as degenerative tricuspid aortic valves. Inflammation needs to be considered in the pathogenesis of acquired aortic stenosis, irrespective of the primary valve anomaly.

The genetics of congenital heart disease: a point in the revolution

Extraordinary diagnostic precision and definitive therapies characterize the current management of congenital heart disease, but the state of the art is not perfect; and in spite of tremendous progress in diagnosis and treatment, our understanding of cause is rudimentary. During the past decade, advances in molecular genetics have defined disease gene loci and lead to identification of genes whose mutations cause congenital heart disease. Identification of additional genes and mutations will lead to improved understanding of pathophysiology of cardiovascular disease in the young. Better understanding of pathophysiology and identification of individuals at risk will provide an opportunity to develop preventive strategies. Taken as a whole, the prospect of understanding the genetic basis of congenital heart disease and translating it into improved diagnostic and therapeutic strategies has never been better.