Changes in size of ascending aorta and aortic valve function with time in patients with congenitally bicuspid aortic valves

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.

Approach to the athlete with thoracic aortic disease

Sports medicine specialists have a unique opportunity to identify individuals who may be at risk for thoracic aortic disease. These patients may have physical features such as tall stature and long limbs (which typify Marfan syndrome), but also lend themselves to participation in competitive athletics. These individuals are at increased risk of sudden death from aortic dissection. Avoiding or delaying aortic complications involves recognition and screening, medications, and prophylactic surgery when the aorta reaches a size threshold. A key feature in management is recognition of the aortic disease and avoiding those sports or exercises that place excess strain or stress on the aorta. Care involves multiple disciplines including primary care physicians, cardiologists, geneticists, ophthalmologists, and orthopedic and cardiac surgeons; however, the sports medicine specialist is often instrumental in guiding the athlete toward proper diagnosis and safe activities in an effort to avoid catastrophic complications.

Progressive dilation of the ascending aorta in children with isolated bicuspid aortic valve

Although patients with bicuspid aortic valves (BAVs) are predisposed to ascending aortic (AA) dilation, stenosis, and dissection, the development of aortic disease in children with BAVs is poorly described. The purposes of this study were to determine the rate of change of AA diameter in children with BAVs and to identify risk factors for the development of aortic dilation. The echocardiograms of 276 children aged<19 years (mean 8.5+/-5.3) with isolated BAVs were reviewed. Aortic measurements were normalized to z scores on the basis of body surface area. In a subset of 112 patients with serial examinations, aortic growth rates were calculated and risk factors for more rapid aortic growth determined. At presentation, 33 patients (12%) demonstrated marked AA dilation (z>4), and 70 (25%) were moderately abnormal (z between 2 and 4). The mean+/-SD AA diameter increased more than expected, at a rate of 0.18+/-0.30 z score per year (p<0.0001). In 61 patients with normal AA diameters on initial study, 22 (36%) had abnormal diameters, with z scores>2, at follow-up. Univariate analysis demonstrated right-noncoronary commissural fusion (p<0.02) and aortic valve gradient on initial examination (p<0.02) as significant predictors of AA growth. In multivariate analysis, however, the significance of gradient and valve morphology was diminished (p = 0.06 for both). In conclusion, the progression of AA diameter in patients with normal z scores on initial examination suggests that serial echocardiograms are required to screen for the development of significant aortic dilation.

Usefulness of bicuspid aortic valve phenotype to predict elastic properties of the ascending aorta

Bicuspid aortic valve (BAV) affects about 0.5% to 2% of the population and predisposes patients to aortic dilation and dissection. We hypothesized that aortic size and elastic properties are related to BAV phenotype. In a retrospective study of 158 consecutive patients with BAV referred for echocardiography, the phenotype was defined as anterior-posterior (A-P) leaflet orientation or right-left (R-L) leaflet orientation. The 29 subjects with R-L BAV were matched 1:1 for age, gender, and grade of aortic valve dysfunction with 29 subjects with A-P BAV. Aortic dimensions were measured at the sinuses of Valsalva, ascending aorta, and aortic arch. Distensibility and stiffness index were calculated using cuff blood pressure. Mean age was 41.5 years (range 21 to 67), and 59% were men. Aortic diameter was larger with A-P BAV than R-L at the sinuses (mean +/- 1 SD 3.48 +/- 0.49 vs 3.06 +/- 0.59, p <0 .01) and smaller at the arch (2.34 +/- 0.40 vs 2.83 +/- 0.45, p <0.001). At the sinuses, A-P BAV had a higher stiffness index (median 12.98, range 2.78 to 42.07 vs 6.41, range 2.75 to 59.72, p <0.01) and lower distensibility. Stiffness index in the ascending aorta and arch (but not at the sinus) increased with age. In conclusion, A-P BAV is associated with a larger stiffer sinus of Valsalva and smaller arch diameter. The potential impact of BAV phenotype and aortic elasticity on clinical outcomes merits further study.

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

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

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.

Comparison of feasibility and accuracy of transthoracic echocardiography versus computed tomography in patients with known ascending aortic aneurysm

Aortic valve diseases, hypertension, and connective tissue disorders may be causes of ascending aortic aneurysms. Aortic enlargement monitoring is essential for surgical timing and for operative design. In this regard, several imaging techniques may have limitations: magnetic resonance is not widespread and is expensive, computed tomography uses radiation, and transesophageal echocardiography is a semi-invasive method. The aim of this study was to analyze the feasibility of transthoracic echocardiography in the evaluation of aortic dimensions and its accuracy in comparison with multidetector computed tomography. In 44 patients with known ascending aortic aneurysms, transthoracic echocardiographic and computed tomographic measurements were obtained and compared at different levels: the annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, and aortic arch. Transthoracic echocardiographic diameters were obtained in all patients, apart from the aortic arch, which was measured in 40 cases. Transthoracic echocardiographic and computed tomographic diameters correlated significantly (p <0.001), with very small SEEs: for the annulus, r = 0.846 (SEE 0.37); for the sinuses of Valsalva, r = 0.967 (SEE 0.35); for the sinotubular junction, r = 0.965 (SEE 0.33); for the ascending aorta, r = 0.976 (SEE 0.41); and for the aortic arch, r = 0.87 (SEE 0.50). In conclusion, transthoracic echocardiography is a feasible and accurate technique for the assessment and follow-up of thoracic aortic diameters in patients with ascending aortic aneurysms.

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

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

Aortic 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.

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.

Echocardiographic anatomy of ascending aorta dilatation: correlations with aortic valve morphology and function

BACKGROUND

Different anatomical forms of proximal aortic dilations associated with aortic valve disease can be distinguished by echocardiography. Differences in the anatomy could reflect different pathogeneses and need for different therapeutic approaches. The present study assessed the clinical features associated to each anatomical form, particularly focusing on the relations with valve morphology and function.

METHODS

Trans-thoracic and trans-esophageal echocardiography reports of 552 adult patients (mean age 60.4+/-12.8 years; 379 male) with mild to severe proximal aorta dilation were reviewed. The relationships between the anatomy of aorta dilatation (distinguished into "root type" dilatation, with maximal enlargement at the sinuses, and "mid-ascending type", with maximal diameter at the mid-ascending tract) and aortic valve morphology (tricuspid/bicuspid) and function (normal/stenosis/regurgitation) were assessed. The relations with other clinico-echocardiographic variables were also tested in univariate and multivariate analysis.

RESULTS

A "root type" dilatation was found in 4.9% tricuspid patients with stenosis, 32.3% with regurgitation, 22.5% with normal valve function (p=0.018). Dilatation prevailed at the mid-ascending tract in patients with bicuspid aortic valve, irrespective of valve function (stenotic: 92.9%, regurgitant: 87.9%, normal: 94.3%; p=0.23). Predominant root involvement was significantly more prevalent in male patients (24.8% versus 5.2% in females; p<0.001). In multivariate analysis, predominant aortic valve regurgitation (OR=1.83; p=0.028) independently predicted root site, while predominant aortic valve stenosis (OR=3.70; p=0.001), bicuspidity (OR=2.90; p=0.005) and female sex (OR=6.10; p<0.001) predicted mid-ascending site.

CONCLUSIONS

Pathogenetical considerations arise from the evidence of preferential mid-ascending localization of bicuspid-associated aortic dilatations. This finding is consistent with previous studies on bicuspid valve models revealing a wall stress overload beyond the sino-tubular ridge.

Valvular Heart Disease

Aortic regurgitation (AR) is characterized by diastolic reflux of blood from the aorta into the left ventricle (LV). Acute AR typically causes severe pulmonary edema and hypotension and is a surgical emergency. Chronic severe AR causes combined LV volume and pressure overload. It is accompanied by systolic hypertension and wide pulse pressure, which account for peripheral physical findings, such as bounding pulses. The afterload excess caused by systolic hypertension leads to progressive LV dilation and systolic dysfunction. The most important diagnostic test for AR is echocardiography. It provides the ability to determine the cause of AR and to assess the severity of AR and its effect on LV size, function, and hemodynamics. Many patients with chronic severe AR may remain clinically compensated for years with normal LV function and no symptoms. These patients do not require surgery but can be followed carefully for the onset of symptoms or LV dilation/dysfunction. Surgery should be considered before the LV ejection fraction falls below 55% or the LV end-diastolic dimension reaches 55 mm. Symptomatic patients should undergo surgery unless there are excessive comorbidities or other contraindications. The primary role of medical therapy with vasodilators is to delay the need for surgery in asymptomatic patients with normal LV function or to treat patients in whom surgery is not an option. The goal of vasodilator therapy is to achieve a significant decrease in systolic arterial pressure. Future therapies may focus on molecular mechanisms to prevent adverse LV remodeling and fibrosis.

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.

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

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

Imaging of the aorta

The aorta is an integral part of the cardiovascular system and should not be considered as just a conduit for blood supply from the heart to the limbs and major organs. A range of important pathologies affect the aorta and are responsible for a high level of morbidity and mortality in affected patients. Many of these conditions are seen in the adult congenital population, especially as advances in diagnosis and treatment mean these patients are surviving well into adulthood. As we gain a greater understanding of these disorders, especially the underlying genetics and pathophysiology, it becomes clear that the aorta is a highly complex part of the vascular tree. As such, the aorta requires increasingly sophisticated imaging techniques for the diagnosis, treatment and follow-up of these patients. The advantages and disadvantages of the various imaging techniques available to clinicians will be discussed in the context of both acute and chronic aortic 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.

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.