Long-term risk of aortic events following aortic valve replacement in patients with bicuspid aortic valves

Bicuspid Aortic Valve: Unlocking the Morphogenetic Puzzle

Although bicuspid aortic valve is the most common congenital abnormality, it is perhaps erroneous to consider this disease one clinical entity. Rather, it may be useful to consider it a cluster of diseases incorporating different phenotypes, etiologies, and pathogenesis. Discussion of bicuspid aortic valve can be difficult because there is no clear consensus on a phenotypic description among authors, and many classification schemes have been proposed. The literature suggests that different phenotypes have different associations and clinical manifestations. In addition, recent studies suggest a genetic basis for the disease, yet few genes have so far been described. Furthermore, recent scientific literature has been focusing on the increased risk of aortic aneurysms, but the pathogenesis of bicuspid aortic valve aortopathy is still unclear. The aim of this paper is to review the current evidence about the unsolved issues around bicuspid aortic valve.

Aortic valve disease with ascending aortic aneurysm: Impact of concomitant root-sparing (supracoronary) aortic replacement in nonsyndromic patients

OBJECTIVE

The purpose of the study was to assess the anticipated incremental risk of a concomitant aortic resection performed with an aortic valve replacement.

METHODS

Patients who underwent aortic valve replacement with root-sparing ascending replacement were compared with those who underwent isolated aortic valve replacement using propensity score matching (81 pairs; mean age, 63 ± 11 years [root-sparing ascending replacement] vs 64 ± 14 years). To evaluate the impact of the technique at distal site, 71 pairs of those undergoing root-sparing ascending replacement also were matched by propensity score according to distal anastomosis performed clamped and open under deep hypothermic circulatory arrest.

RESULTS

Operative mortality was equal between the root-sparing ascending replacement and isolated aortic valve replacement groups. No significant difference was found regarding postoperative morbidities, such as bleeding, renal failure, stroke, and length of stay, except prolonged ventilation was found after root-sparing procedures (P = .028). Survival estimation showed no difference between the groups. Comparing the patients undergoing root-sparing ascending replacement with clamped and opened distal anastomosis revealed a prolonged ventilation requirement (7% vs 3%; P = not significant) in the open group. Operative mortality was 0% in both groups, and midterm survival was comparable.

CONCLUSIONS

The concomitant replacement of the aorta in root-sparing fashion is associated with an excellent operative outcome and adds no additional risk to aortic valve replacement in elective and non-high-risk patients. If the distal anastomosis is performed in an open fashion, while the operative mortality is still very low, morbidities are slightly higher, but midterm survival remains comparable.

Combination of a Giant Dissected Ascending Aortic Aneurysm with Multiple Fistulae into the Cardiac Chambers Caused by Prosthetic Aortic Valve Endocarditis

The combination of a dissected ascending aortic aneurysm (AA) with multiple fistulae to the periaortic root structures is a life-threatening complication that occurs rarely after infective endocarditis of the prosthetic aortic valve. Many risk factors are potentially associated with this complication, including aortic diameter, connective tissue disease of the aortic wall, hypertension and infection. We report a rare case of dissected ascending AA with fistulae to the left atrium and pulmonary artery and a paravalvular leak in a 47-year-old woman with a history of an aortic valve replacement. The patient had presented to the Imam Ali Hospital, Kermanshah, Iran, in January 2015 with clinical features of heart failure. After initially being treated for congestive heart failure, she underwent open-heart surgery via a classic Bentall procedure and double fistula closure. She was discharged 23 days after the operation in good condition. A six-month follow-up showed normal functioning of the composite conduit prosthetic valve and no fistulae recurrence.

Are normal-sized ascending aortas at risk of late aortic events after aortic valve replacement for bicuspid aortic valve disease?

OBJECTIVES

Bicuspid aortic valve (BAV)-associated aortopathy has been proposed to progress after isolated aortic valve replacement (AVR) surgery, which has been traditionally used as an argument against a TAVR procedure in this clinical subset. Still, more than half of BAV patients have a normal-sized proximal aorta at the time of AVR surgery. We aimed to analyse the long-term risk of adverse aortic events after isolated conventional AVR surgery for BAV and normal-sized proximal aorta.

METHODS

A total of 200 consecutive patients (mean age 56 ± 13 years, 73% men) with BAV disease and ascending aortic diameter of <40 mm underwent isolated conventional AVR from 1995 through 2008 and were identified from our institutional BAV database. Long-term follow-up data (a total of 1532 patient-years) were obtained for all hospital survivors. Composite adverse aortic/cardiovascular events were defined as the need for redo aortic surgery, the occurrence of aortic dissection/rupture, or sudden cardiac death during follow-up.

RESULTS

A total of 25 (13%) patients died after a mean follow-up of 8.5 ± 5 years post-AVR surgery, which resulted in an overall survival rate of 75 ± 6 and 87 ± 7% at 15 years postoperatively, for BAV-aortic stenosis and BAV-aortic regurgitation, respectively (P = 0.6). An adverse aortic event occurred in 1 (0.5%) study patient, while 5 (2.5%) further patients suffered sudden cardiac death. Only 1 patient required redo aortic surgery. No documented aortic dissection/rupture occurred. Redo AVR surgery due to endocarditis or structural valve degeneration was performed in 6 (3%) patients. The rate of freedom from composite adverse events was 92 ± 5 and 95 ± 4% at 15 years, for the AS and AR subgroups, respectively (P = 0.7).

CONCLUSIONS

BAV patients with aortic valve dysfunction and normal-sized ascending aorta are at considerably low risk of late adverse aortic events after isolated AVR.

Comparative Histology of Aortic Dilatation Associated With Bileaflet Versus Trileaflet Aortic Valves

BACKGROUND

A more aggressive posture toward resection of the dilated aorta has been advocated when associated with bicuspid aortic valve (BAV), based on the notion that aortic material properties are weaker in this setting despite scant data to support or refute this position. The hypothesis that histologic abnormality reflects aortic wall strength was tested by comparing aortas from patients with BAV and trileaflet aortic valve.

METHODS

Resected aortas associated with BAV (n = 60) and trileaflet aortic valve (n = 24) were compared with normal diameter aortas from patients undergoing cardiac transplantation (n = 16) by five histologic criteria: elastic fiber loss (graded 0-4), smooth muscle cell loss (graded 0-4), medial proteoglycan accumulation (graded 0-3), medial fibrosis (graded 0-3), and atherosclerosis (graded 0-3). Patients with known connective tissue disorders, systemic inflammatory conditions, dissection, or prior heart surgery were excluded.

RESULTS

Patients with BAV were a decade younger and more often had functional stenosis. The extent of elastic fiber loss, smooth muscle cell loss, medial fibrosis, and atherosclerosis was more severe in trileaflet aortic valve than BAV when considered across all diameters and when stratified to those between 4 and 5 cm.

CONCLUSIONS

More severe histologic abnormalities associated with trileaflet aortic valve compared with BAV, especially when stratified by diameter, do not support a more aggressive approach to surgical intervention for dilatation associated with BAV. Indeed, if based on histologic diagnosis alone, our findings are suggestive that the converse might be true. Additionally, the lack of correlation between aortic diameter and histologic abnormality in the setting of BAV highlights the inadequacy of diameter alone as a criterion for aortic resection.

Bicuspid aortic valve aortopathy in adults: Incidence, etiology, and clinical significance

Bicuspid aortic valve is the most common congenital heart defect and is associated with an aortopathy manifested by dilatation of the ascending thoracic aorta. The clinical consequences of this aortopathy are the need for periodic monitoring of aortic diameters, elective prophylactic surgical aortic repair, and the occurrence of aortic dissection or rupture. This review describes the current knowledge of BAV aortopathy in adults, including incidence, pathophysiologic insights into its etiology, contemporary hypothesis-generating observations into its complications, and recommendations for monitoring and intervention.

Aortic Dissection in Patients With Bicuspid Aortic Valve-Associated Aneurysms

BACKGROUND

Data regarding the risk of aortic dissection in patients with bicuspid aortic valve and large ascending aortic diameter are limited, and appropriate timing of prophylactic ascending aortic replacement lacks consensus. Thus our objectives were to determine the risk of aortic dissection based on initial cross-sectional imaging data and clinical variables and to isolate predictors of aortic intervention in those initially prescribed serial surveillance imaging.

METHODS

From January 1995 to January 2014, 1,181 patients with bicuspid aortic valve underwent cross-sectional computed tomography (CT) or magnetic resonance imaging (MRI) to ascertain sinus or tubular ascending aortic diameter greater than or equal to 4.7 cm. Random Forest classification was used to identify risk factors for aortic dissection, and among patients undergoing surveillance, time-related analysis was used to identify risk factors for aortic intervention.

RESULTS

Prevalence of type A dissection that was detected by imaging or was found at operation or on follow-up was 5.3% (n = 63). Probability of type A dissection increased gradually at a sinus diameter of 5.0 cm--from 4.1% to 13% at 7.2 cm--and then increased steeply at an ascending aortic diameter of 5.3 cm--from 3.8% to 35% at 8.4 cm--corresponding to a cross-sectional area to height ratio of 10 cm(2)/m for sinuses of Valsalva and 13 cm(2)/m for the tubular ascending aorta. Cross-sectional area to height ratio was the best predictor of type A dissection (area under the curve [AUC] = 0.73).

CONCLUSIONS

Early prophylactic ascending aortic replacement in patients with bicuspid aortic valve should be considered at high-volume aortic centers to reduce the high risk of preventable type A dissection in those with aortas larger than approximately 5.0 cm or with a cross-sectional area to height ratio greater than approximately 10 cm(2)/m.

Current topics on bicuspid aortic valve: clinical aspects and surgical management

Bicuspid aortic valve (BAV) has been identified as the most common heart valve anomaly and is considered to be a heritable disorder that affects various cardiovascular disorders, including aortopathy. Current topics regarding the clinical management of BAV including surgical strategies with or without concomitant aortic repair or replacement are attracting interest, in addition to the pathological and morphological aspects of BAV as well as aortopathy. However, surgical indications are still being debated and are dependent on current clinical guidelines and surgeons' preferences. Although clinical guidelines have already been established for the management of BAV with or without aortopathy, many studies on clinical management and surgical techniques involving various kinds of subjects have previously been published. Although a large number of studies concerning the clinical aspects of BAV have been reviewed in detail, controversy still surrounds the clinical and surgical management of BAV. Therefore, surgeons should carefully consider valve pathology when deciding whether to replace the ascending aorta. In this review, we summarized current topics on BAV and the surgical management of diseased BAV with or without aortopathy based on previous findings, including catheter-based interventional management.

Comparative transcriptome profiling in human bicuspid aortic valve disease using RNA sequencing

Intrinsic valvular degeneration and dysfunction is the most common complication of bicuspid aortic valve (BAV) disease. Phenotypically, it ranges from calcific aortic stenosis to redundant or prolapsing regurgitant leaflets. The underlying molecular mechanism underpinning phenotype heterogeneity of valvular degeneration in BAV is poorly understood. We used RNA sequencing (RNA-seq) to identify genes and pathways responsible for the development of valvular degeneration in BAV, compared with tricuspid aortic valve (TAV). Comparative transcriptome analysis was performed on total RNA of aortic valve tissues of patients with diseased BAV ( n = 5) and calcified TAV ( n = 3). RNA-seq findings were validated by RT-qPCR. A total of 59 and 177 genes were significantly up- and downregulated, respectively, in BAV compared with TAV. Hierarchical clustering indicated heterogeneity within the BAV group, separating those with heavy calcification (BAVc) from those with redundant leaflets and/or minimal calcification (BAVr). Interestingly, the gene expression profile of the BAVc group closely resembled the TAV, with shared up- and downregulation of inflammatory and NOTCH1 signaling pathways, respectively. Downregulation of matrix protease ADAMTS9 and protein aggrecan were observed in BAVr compared with TAV. Dysregulation of fetal gene programs were also present, with notable downregulation of SEMA6B and SEMA3F in BAVr and BAVc compared with TAV, respectively. Upregulation of TBX20 was observed exclusively in BAVr compared with BAVc. In conclusion, diverging molecular mechanisms underpin phenotype heterogeneity of valvular degeneration in BAV and data from the present study suggest that there may be shared mechanisms leading to calcification in BAV and TAV. Recognition of these pathways is fundamental to improve our understanding of the molecular basis of human BAV disease.

Aortic wrapping for a dilated ascending aorta in bicuspid aortic stenosis

BACKGROUND

Ascending aorta wrapping is rarely recommended for the management of dilated aorta, because of late complications. The aim of the present study was to analyze the early and late outcomes of the aortic wrapping technique at the time of aortic valve replacement (AVR) for bicuspid aortic stenosis (BAS).

METHODS AND RESULTS

Among patients who underwent primary AVR for BAS between 2002 and 2011, 79 who underwent ascending aortic wrapping (wrapping group) were compared with 144 patients who underwent AVR alone. The preoperative ascending aortic diameters were larger in the wrapping group (40.9±4.2 mm vs. 48.6±4.0 mm, P<0.001). Operative technique was to wrap the ascending aorta transversely with a semi-elliptically resected Dacron graft. The follow-up for the wrapping group was 76.5±35.5 (median 71.1) months. There were no early deaths. Early and late morbidity did not differ between groups. The 24 late deaths, including 10 cardiac-related deaths, occurred in the entire group; 3 sudden deaths occurred only in the AVR group. The 10-year overall survival in the wrapping group was higher than the AVR group (88.1±6.8% vs. 80.0±4.6%, P=0.048). No late aortic complications were detected. The aortic diameter was reduced from 49.5±4.1 mm to 45.3±5.0 mm after wrapping (P<0.001).

CONCLUSIONS

The aortic wrapping technique may be an option for treating a moderately dilated ascending aorta in selected patients undergoing AVR for BAS. Longer follow-up, however, is necessary to verify later complications.

Prosthesis-preserving aortic root repair after aortic valve replacement

We describe a new technique of prosthesis-preserving aortic root replacement for patients who have previously undergone aortic valve replacement. With preservation of the mechanical prosthesis, we implant a Gelweave Valsalva graft using double suture lines. The first suture line is made between the sewing cuff of the mechanical valve and the graft, with mattress sutures of 2/0 braided polyester with pledgets. After the first sutures are tied, the second suture line is created between the graft collar and the aortic root remnant with continuous 4/0 polypropylene sutures.

A giant dissecting aneurysm of ascending aorta following aortic valve replacement

Ascending aortic dissection and aneurysm are rare but life-threatening complications after aortic valve replacement. Preoperative evaluation of risk factors such as aortic diameter, structural features of aortic wall, and associated diseases may decrease complication rate. We herein present analysis of risk factors of proximal aortic events following aortic valve replacement based on patient with giant dissecting aneurysm who underwent modified Bentall procedure.

Late outcome of noncoronary sinus replacement in patients with bicuspid aortic valves and aortopathy

BACKGROUND

Aortopathy associated with bicuspid aortic valve commonly involves the ascending aorta above the sinotubular ridge, but it may also affect sinus portions of the aorta. In some persons, the enlarged portion of the aortic root is limited to the noncoronary sinus. In such patients, we have spared the remaining portions of the aortic root by replacing the ascending aorta with a polyethylene terephthalate fiber (Dacron) graft and a tongue-shaped extension of the graft, thereby replacing the noncoronary sinus. In the present study, we evaluated late outcomes of this procedure, with specific attention to the fate of aortic tissue in the remaining sinuses.

METHODS

We reviewed the medical records of 1,756 patients with repair of ascending aortic aneurysms at Mayo Clinic from 1993 through 2012. Among the patients, 631 (35.9%) had bicuspid aortic valve, and in 79 (4.5%) of the patients, the noncoronary sinus was replaced along with the ascending aorta.

RESULTS

Associated aortic valve operations were performed in 70 patients; 15 had repair and 55 had aortic valve replacement. No early death occurred, but 3 patients died late after operation (5-year survival, 99%). There were 3 late reoperations, all because of native or prosthetic valve problems. Importantly, no instances occurred of aneurysm formation or aortic dissection related to the remaining aorta in the left and right aortic sinuses.

CONCLUSIONS

In patients with bicuspid aortic valve and aortic root enlargement related mainly to enlargement of the noncoronary sinus, limited replacement of the noncoronary sinus and ascending aorta is a safe and simple procedure that is durable in midterm follow-up.

The fate of the bicuspid valve aortopathy after aortic valve replacement

OBJECTIVES

The fate of the aortic dimensions in patients with a bicuspid aortic valve (BAV) after aortic valve replacement (AVR) is unclear. We investigated the evolution of aortic root and ascending aorta dimensions in patients with a BAV after AVR. To neutralize the effect of pathological transvalvular haemodynamics on aortic dimensions, we evaluated our hypotheses in patients with normal transvalvular haemodynamics after a subcoronary autograft procedure, which preserves intact the native aortic wall.

METHODS

We excluded patients operated on for endocarditis; who developed autograft insufficiency > trivial and who required autograft reoperation during the follow-up. We included 448 patients (361 with BAV; 340 males; 44.6 ± 11.4 years; mean follow-up: 7.5 ± 3.9 years). Valve phenotype was determined during surgery. Annual echocardiographic examinations (n = 3336) were performed (follow-up completeness: 98%). To allow for somatometric, gender and age influences, z-values of measurements were calculated from the general population (GP) and analysed using longitudinal methods.

RESULTS

The increase in ascending aorta did not differ from that expected in the GP (0.04 z-values/year; P = 0.06). No difference could be observed in diameter increase rates between BAV and tricuspid aortic valve patients (TAV) (0.04 vs 0.06 z-values/year; P = 0.3), as well as between BAV phenotypes. The sinus increase did not differ from that expected in the GP (0.03 z-values/year; P = 0.1), and no significant differences could be observed between BAV phenotypes. In patients undergoing aortoplasty (n = 70), no significant difference in the rates of ascending aorta and sinus increase could be observed, compared with the GP.

CONCLUSION

For the time period of this study and in patients with normal aortic root haemodynamics after AVR, ascending aorta dimensions over time are similar to that of the matched GP. Patients with a BAV did not exhibit higher rates of ascending aorta dilatation after AVR than patients with TAV. At least for the first postoperative decade, transvalvular haemodynamics appear to exhibit a greater influence than the genetic component of BAV on the development of the BAV aortopathy.

Correlation between systolic transvalvular flow and proximal aortic wall changes in bicuspid aortic valve stenosis

OBJECTIVES

The purpose of this study was to analyse the correlation between preoperative systolic transvalvular flow patterns and proximal aortic wall lesions in patients undergoing surgery for bicuspid aortic valve (BAV) stenosis.

METHODS

A total of 48 consecutive patients with BAV stenosis (mean age 58 ± 9 years, 65% male) underwent aortic valve replacement (AVR) ± proximal aortic surgery from January 2012 through February 2013. Preoperative cardiac phase-contrast cine magnetic resonance imaging (MRI) assessment was performed in all patients in order to detect the area of maximal flow-induced stress in the proximal aorta. Based on these MRI data, two aortic wall samples (i.e. area of the maximal stress (jet sample) and the opposite aortic wall (control sample)) were collected during AVR surgery. Aortic wall changes were graded based on a summation of seven histological criteria (each scored from 0 to 3). Histological sum score (0-21) was separately calculated and compared between the two aortic samples (i.e. jet sample vs control sample).

RESULTS

An eccentric transvalvular flow jet hitting the proximal aortic wall could be identified in all 48 (100%) patients. The mean histological sum score was significantly higher in the jet sample vs control sample areas of the aorta (i.e. 4.1 ± 1.8 vs 2.2 ± 1.5, respectively) (P = 0.02). None of the patients had a higher sum score value in the control sample.

CONCLUSIONS

Our study demonstrates a strong correlation between the systolic pattern of the transvalvular flow jet and asymmetric proximal aortic wall changes in patients undergoing AVR for BAV stenosis.

Risk of proximal aortic dissection in patients with bicuspid aortic valve: how to address this controversy?

The risk of acute aortic events in patients with bicuspid aortic valve (BAV) disease is a controversial issue. The real risk of aortic dissection in patients with BAV disease is unknown. An indirect assessment of this risk, however, could be gained with a more detailed understanding of the pathogenesis of BAV aortopathy. There are two major issues that should be clarified before one addresses the question of aortic dissection risk in BAV patients. The first issue, when analysing the data from previous BAV cohorts, is to determine what stage of BAV disease was present in the described patient population. In particular, was the risk of aortic dissection in BAV patients determined before or after aortic valve replacement (AVR) surgery? The second issue to consider is the functional state of the pathological valve within the observed population. In particular, did patients predominantly suffer from BAV stenosis or BAV insufficiency? Unfortunately, the vast majority of published reports do not separate between the different BAV phenotypes, thereby complicating interpretation of the results. Considering these two important clinical variables (i.e. the stage of BAV disease and the functional phenotype), we herein aim to explain the inconsistency of the published data with regard to the risk of aortic dissection in patients with BAV disease.

Knowledge, attitudes, and practice patterns in surgical management of bicuspid aortopathy: a survey of 100 cardiac surgeons

OBJECTIVE

Clinical practice guidelines have been established for surgical management of the aorta in bicuspid aortic valve disease. We hypothesized that surgeons' knowledge of and attitudes toward bicuspid aortic valve aortopathy influence their surgical approaches.

METHODS

We surveyed cardiac surgeons to probe the knowledge of, attitudes toward, and surgical management of bicuspid aortopathy. A total of 100 Canadian adult cardiac surgeons participated.

RESULTS

Fifty-two percent of surgeons believed that the mechanism underlying aortic dilation in those with bicuspid aortic valve was due to an inherent genetic abnormality of the aorta, whereas only 2% believed that altered valve-related processes were involved in this process. Only a minority (15%) believed that bicuspid valve leaflet fusion type is associated with a unique pattern of aortic dilatation aortic phenotype. Sixty-five percent of surgeons recommended echocardiographic screening of first-degree relatives of patients with bicuspid aortic valve. Most surgeons (61%) elected to replace the aorta when the diameter is 45 mm or greater at the time of valve surgery. Fifty-five percent of surgeons surveyed suggested that in the absence of concomitant valvular disease, they would recommend ascending aortic replacement at a threshold of 50 mm or greater. Approximately one third of surgeons suggested that they would elect to replace a mildly dilated ascending aorta (40 mm) at the time of valve surgery. The most common surgical approach (61%) for combined valve and aortic surgery was aortic valve replacement and supracoronary replacement of the ascending aorta, and only a minority suggested the use of deep hypothermic circulatory arrest and open distal anastomosis. More aggressive approaches were favored with greater surgeon experience, and when circulatory arrest was chosen, the majority (68%) suggested they would use antegrade cerebral perfusion. In the setting of aortic insufficiency and a dilated aorta, 42% of surgeons suggested that they would perform valve-sparing surgery. Of note, 40% of respondents used an index measure of aortic size to body surface area in addition to absolute aortic diameter in assessing the threshold for intervention.

CONCLUSIONS

This large survey uncovered significant gaps in the knowledge and attitudes of surgeons toward the diagnosis and management of bicuspid aortopathy, many of which were at odds with current guideline recommendations. Efforts to promote knowledge translation in this area are strongly encouraged.

Management of dilated ascending aorta during aortic valve replacement: valve replacement alone versus aorta wrapping versus aorta replacement

OBJECTIVES

The optimal management of dilated ascending aorta during aortic valve replacement (AVR) remains controversial. This study compared the outcomes among 3 different managements (AVR alone, aorta wrapping, and aorta replacement) for the dilated ascending aorta.

METHODS

The study enrolled 499 consecutive non-Marfan patients undergoing AVR in the presence of the ascending aorta dilatation (40 to 55 mm). We evaluated rates of death and aortic events; in addition, we evaluated the aortic expansion rate by serial echocardiography.

RESULTS

The surgery involved AVR alone (n = 362), aorta wrapping (n = 67), or aorta replacement (n = 70). Early mortality occurred in 1.2% (n = 6, P = .61). Throughout 1590.0 patient-years of follow-up, 47 deaths occurred. The 5-year survival rates were 90.1% ± 2.0%, 91.8% ± 3.5%, and 82.2% ± 7.5% in the AVR alone, aorta wrapping, and aorta replacement groups, respectively (P = .64). One aortic event (acute type A dissection) occurred in the AVR alone group. For the AVR alone group, the median aortic expansion rate was -0.6 mm/y (interquartile range, -3.2 to 0.6 mm/y). The aortic expansion rates were affected neither by the morphology of aortic valves (bicuspid vs tricuspid; P = .10) nor by the initial aorta diameter (γ = -0.31, P = .61). Clinically relevant aortic expansion (≥5 mm/y) was observed only in 5 patients; of these patients, 2 showed the aortic diameter of 60 mm or greater at the end of follow-up.

CONCLUSIONS

Compared with concomitant aortic wrapping or replacement, AVR alone achieved similar clinical outcomes, showing considerably low risks of adverse aortic events or relevant aortic expansion in dilated ascending aorta. These findings argue against routine aortic replacement at the time of AVR.

New Insights Into Aortic Diseases: A Report From the Third International Meeting on Aortic Diseases (IMAD3)

The current state of research and treatment on aortic diseases was discussed in the "3rd International Meeting on Aortic Diseases" (IMAD3) held on October 4-6, 2012, in Liège, Belgium. The 3-day meeting covered a wide range of topics related to thoracic aortic aneurysms and dissections, abdominal aortic aneurysms, and valvular diseases. It brought together clinicians and basic scientists and provided an excellent opportunity to discuss future collaborative research projects for genetic, genomics, and biomarker studies, as well as clinical trials. Although great progress has been made in the past few years, there are still a large number of unsolved questions about aortic diseases. Obtaining answers to the key questions will require innovative, interdisciplinary approaches that integrate information from epidemiological, genetic, molecular biology, and bioengineering studies on humans and animal models. It is more evident than ever that multicenter collaborations are needed to accomplish these goals.

Dilatation of the remaining aorta after aortic valve or aortic root replacement in patients with bicuspid aortic valve: a 5-year follow-up

BACKGROUND

The natural history and management of ascending aorta (AA) and arch dilatation in patients with bicuspid aortic valve (BAV) after aortic valve replacement (AVR) or aortic root replacement (ARR) remains controversial. Our aim is to identify dilatation of the remaining aorta after AVR or ARR in patients with BAV compared with patients with tricuspid aortic valve (TAV).

METHODS

Three hundred ninety-five patients who underwent AVR or ARR between 2002 and 2009 were studied. Preoperative computed tomography (CT) and echocardiography were performed in 192 patients with BAV, and the results were compared with those of 203 patients with TAV. An AA diameter 4.5 cm or greater was regarded as aneurysmal. Postoperative echocardiograms, computed tomographic scans, and magnetic resonance images were compared with subsequent imaging at a median follow-up of 4.6 years (2.2-9.8 years).

RESULT

Median ages of patients with BAV and patients with TAV were 57 ± 14 and 65 ± 16 years, respectively (p < 0.05). Preoperative diameter of AA in the BAV group with no aneurysm (3.5 cm; range, 3.0-4.0 cm; n = 143) was significantly higher than in the TAV group (3.3 cm; range, 3.1-3.8 cm; n = 129) (p < 0.001). In both BAV and TAV groups with nonaneurysmal aortas who underwent AVR, there was no significant expansion of the AA and arch at 5 years' follow-up. In patients with aneurysmal aorta (BAV group, n = 49; TAV group, n = 74) who underwent ARR, there was also no significant difference in growth of the remaining aorta at 3 and 5 years' follow-up.

CONCLUSIONS

No significant dilatation of the AA or arch was observed after AVR or ARR, respectively, in patients when a cut-off diameter of 4.5 cm or greater was considered for replacement in patients with BAV compared with patients with TAV up to 5 years after operation. The need for aortic replacement at smaller diameters was not found.

Indications for aortic aneurysmectomy: too many variables and not enough equations?

Endografting for treatment of thoracic aortic pathology continues to gain popularity; in some countries, endovascular aortic repair numbers now exceed open surgery cases. The skills and understanding of open surgical teams are not always translated into endovascular interventions, which may be led by a cardiologist or vascular surgeon with little knowledge of thoracic pathology. The indications for intervention on the dilated aorta continue to be debated despite volumes of literature and multisocietal guidelines. The challenge of making a binary decision in the face of competing continuous risks depends on a best guess as to when the risk of the natural history of the disease exceeds that of the operation. Unfortunately, we have more information about average risk than actual (patient-specific) risk, and only for some of the variables determining those risks. Individual patient-specific operative risk can be calculated for some procedures by means of the Society of Thoracic Surgeons database, although surgeon-specific risk models are really required. On the other side of the balance, aortic dissection and rupture represent material failure of the aortic wall when tensile stress exceeds tensile strength. When framed in this way, it is not surprising that diameter is imprecise, as this is only one of the variables in the law of Laplace. The circumferential (hoop) stress is the product of radius and intraluminal pressure, divided by wall thickness. We also have no good measures of the material properties of the wall that determine strength, although a great deal of attention has been paid to the genetic markers for aortic wall abnormalities. Other factors, such as smoking or poorly controlled hypertension, likely should enter into our clinical assessment because they impact wall strength as well. For now, discussions with patients should be framed with all these elements in mind.

Does additional aortic procedure carry a higher risk in patients undergoing aortic valve replacement?

Background

With growing attention to the aortopathy associated with aortic valve diseases, the number of candidates for accompanying ascending aorta and/or root replacement is increasing among the patients who require aortic valve replacement (AVR). However, such procedures have been considered more risky than AVR alone. This study aimed to compare the surgical outcome of isolated AVR and AVR combined with aortic procedures.

Materials and Methods

A total of 86 patients who underwent elective AVR between 2004 and June 2010 were divided into two groups: complex AVR (n=50, AVR with ascending aorta replacement in 24 and the Bentall procedure in 26) and simple AVR (n=36). Preoperative characteristics, surgical data, intra- and postoperative allogenic blood transfusion requirement, the postoperative clinical course, and major complications were retrospectively reviewed and compared.

Results

The preoperative mean logistic European System for Cardiac Operative Risk Evaluation (%) did not differ between the groups: 11.0±7.8% in the complex AVR group and 12.3±8.0% in the simple AVR group. Although complex AVR required longer cardiopulmonary bypass (152.4±52.6 minutes vs. 109.7±22.7 minutes, p=0.001), the quantity of allogenic blood products did not differ (13.4±14.7 units vs. 13.9±11.2 units). There was no mortality, mechanical circulatory support, stroke, or renal failure requiring hemodialysis/filtration. No difference was found in the incidence of bleeding (40% vs. 33.3%) which was defined as red blood cell transfusion ≥5 units, reoperation, or intentional delayed closure. The incidence of mediastinitis (2.0% vs. 0%), ventilator ≥24 hours (4.0% vs. 2.8%), atrial fibrillation (18.0% vs. 25.0%), mean intensive care unit stay (34.5 hours vs. 38.8 hours), and median hospital stay (8 days vs. 7 days) did not differ, either.

Conclusion

AVR combined with additional aortic or root replacement showed an excellent outcome and recovery course equivalent to that after isolated AVR.

Ascending aortic wall cohesion: comparison of bicuspid and tricuspid valves

Objectives. Bicuspid aortic valve (AV) represents the most common form of congenital AV malformation, which is frequently associated with pathologies of the ascending aorta. We compared the mechanical properties of the aortic wall between patients with bicuspid and tricuspid AV using a new custom-made device mimicking transversal aortic wall shear stress. Methods. Between 03/2010 and 07/2011, 190 consecutive patients undergoing open aortic valve replacement at our institution were prospectively enrolled, presenting either with a bicuspid (group 1, n = 44) or a tricuspid (group 2, n = 146) AV. Aortic wall specimen were examined with the “dissectometer” resulting in nine specific aortic-wall parameters derived from tensile strength curves (TSC). Results. Patients with a bicuspid AV showed significantly more calcified valves (43.2% versus 15.8%, P < 0.001), and a significantly thinner aortic wall (2.04 ± 0.42 mm versus 2.24 ± 0.41 mm, P = 0.008). Transesophageal echocardiography diameters (annulus, aortic sinuses, and sinotubular junction) were significantly larger in the bicuspid group (P = 0.003, P = 0.02, P = 0.01). We found no difference in the aortic wall cohesion between both groups as revealed by shear stress testing (P = 0.72, P = 0.40, P = 0.41). Conclusion. We observed no differences of TSC in patients presenting with tricuspid or bicuspid AVs. These results may allow us to assume that the morphology of the AV and the pathology of the ascending aorta are independent.

Bicuspid aortic valve and thoracic aortic aneurysm: three patient populations, two disease phenotypes, and one shared genotype

Bicuspid aortic valve (BAV) and thoracic aortic aneurysm (TAA) are two discrete cardiovascular phenotypes characterized by latent progressive disease states. There is a clear association between BAV and TAA; however the nature and extent of this relationship is unclear. There are both distinct and overlapping developmental pathways that have been established to contribute to the formation of the aortic valve and the aortic root, and the mature anatomy of these different tissue types is intimately intertwined. Likewise, human genetics studies have established apparently separate and common contributions to these clinical phenotypes, suggesting complex inheritance and a shared genetic basis and translating 3 patient populations, namely, BAV, TAA, or both, into a common but diverse etiology. A better understanding of the BAV-TAA association will provide an opportunity to leverage molecular information to modify clinical care through more sophisticated diagnostic testing, improved counseling, and ultimately new pharmacologic therapies.

Histological and genetic studies in patients with bicuspid aortic valve and ascending aorta complications

OBJECTIVES

Aneurysm diameter and growing rate does not represent a definite parameter for operation in bicuspid aortic valve (BAV), ascending aortic aneurysm and normal root patients. Thus, we investigated histological and immunohistochemical aspects of different segments of ascending aorta (precisely, aortic root without dilatation, aneurysmatic tubular portion, dissected ascending aorta) and genetic features of patients with BAV and ascending aorta complication (aneurysm or dissection).

METHODS

Aorta tissue samples of 24 BAV patients were examined. The patients comprised of 18 men and 6 women; the mean age was 54.2 ± 14.3 years. All patients underwent composite aortic root replacement (button Bentall operation). Multiple histological sections were prepared from each aortic specimen. The evaluated features included elastic fibre fragmentation, cystic medial change, smooth muscle cell necrosis, medial fibrosis, and the markers of medial apoptosis and the metalloproteinases. Furthermore, genetic risk factors were also investigated.

RESULTS

The same medial degenerative lesions in tissue samples of different aorta segments (precisely of aortic root without dilatation, and aneurysmatic ascending aorta portion) were observed. More significant associations between single nucleotide polymorphisms (-786T/C endothelial nitric oxide synthase enzyme, D/I angiotensin-converting enzyme, -1562C/T metalloproteinase-9 and -735C/T metalloproteinase-2) and aneurysm risk were detected in BAV patients than in controls.

CONCLUSIONS

Based on our histological and genetic data, we underline that a surgical approach in patients with BAV, ascending aortic aneurysm and normal root, should consider not only the diameter of the aneurysmatic aortic portion but also the histological features of the whole ascending aorta and the genetic risk profile.