An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta.

A number of patients who require an operation for complications of annuloaortic ectasia, such as aortic incompetence or aneurysm of the aortic root (or both), have normal aortic valve leaflets. We have treated these patients by excising the aneurysmal portion of the ascending aorta and sinuses of Valsalva but by leaving the aortic valve leaflets and some arterial wall attached to the left ventricular outflow tract. The aortic valve is reimplanted inside a collagen-impregnated tubular Dacron graft, similar to what is done for implantation of an aortic valve homograft. The coronary arteries are also reimplanted. This operation was performed in 10 patients. All patients had annuloaortic ectasia and five had the stigmata of Marfan syndrome. Four patients had acute aortic dissection. There were no operative deaths, but one patient required composite replacement of the aortic valve and ascending aorta because of persistent aortic incompetence. Postoperative Doppler echocardiography revealed normal aortic valve function in six patients and mild incompetence in three. The preliminary results of this new operation are encouraging. Further investigation is necessary to establish the best size, shape, and type of material that should be used to replace the aortic root while preserving the aortic valve.     

Results of surgery for aortic root aneurysm in patients with the Marfan syndrome.

OBJECTIVE: To evaluate the results of two operations, aortic valve-sparing and aortic root replacement, in patients with aortic root aneurysm and the Marfan syndrome. METHODS: A retrospective review of 78 consecutive patients with aortic root aneurysm and the Marfan syndrome according to the Gent criteria indicated that 42 patients with normal aortic cusps had an aortic valve-sparing operation, and 36 patients had aortic root replacement (mechanical valve in 25 patients and biological valve in 11). The mean age was similar in both groups, but patients who had aortic root replacement had larger aneurysms, higher grade aortic insufficiency, worse left ventricular function and more cardiac co-morbidity than patients who had aortic valve-sparing operations. The mean follow-up was 41+/-35 months for patients who had aortic valve-sparing, and 65+/-50 months for those who had aortic root replacement. RESULTS: Kaplan-Meyer estimates of survival at 5 years was 100% for patients who had aortic valve-sparing, and 88+/-6% for those who had aortic root replacement (P=0.04). Five patients who had aortic root replacement required seven aortic root re-replacements: three for endocarditis and four for valve failure (biological valves). There have been no reoperations in patients who had aortic valve-sparing operations and annual Doppler echocardiography revealed mild or no aortic insufficiency in 39 patients and moderate aortic insufficiency in three. CONCLUSIONS: These data suggest that aortic valve-sparing operations are safe in patients with the Marfan syndrome and may provide better clinical outcomes than aortic root replacement. Since the size of the aneurysm often determines the feasibility of a valve-sparing procedure, we now recommend surgery when the diameter of the aortic root reaches 50 mm in patients with the Marfan syndrome who have echocardiographically normal aortic valve cusps.     

Time-resolved three-dimensional magnetic resonance velocity mapping of aortic flow in healthy volunteers and patients after valve-sparing aortic root replacement

OBJECTIVE: To provide more complete characterization of ascending aortic blood flow, including vortex formation behind the valve cusps, in healthy subjects and patients after valve-sparing aortic root replacement (David reimplantation). METHODS: Time-resolved 3-dimensional magnetic resonance imaging velocity mapping was performed to analyze pulsatile blood flow by using encoded 3-directional vector fields in the thoracic aortas of 10 volunteers and 12 patients after David reimplantation using a cylindrical tube graft (T. David I) and two versions of neosinus recreation (T. David-V and T. David-V-S mod ). Aortic flow was evaluated by using 3-dimensional time-resolved particle traces and velocity vector fields reformatted onto 2-dimensional planes. Semiquantitative data were derived by using a blinded grading system (0-3: 0, none; 1, minimal; 2, medium; 3, prominent) to analyze the systolic vortex formation behind the cusps, as well as retrograde and helical flow in the ascending aorta. RESULTS: Systolic vortices were seen in both coronary sinuses of all volunteers (greater in the left sinus [2.5 +/- 0.5] than the right [1.8 +/- 0.8]) but in only 4 of 10 noncoronary sinuses (0.7 +/- 0.9). Comparable coronary vortices were detected in all operated patients. Vorticity was minimal in the noncoronary cusp in T. David-I repairs (0.7 +/- 0.7) but was prominent in T. David-V noncoronary graft pseudosinuses (1.5 +/- 0.6; P = .035). Retrograde flow (P = .001) and helicity (P = .028) were found in all patients but were not distinguishable from normal values in the T. David-V-S mod patients. CONCLUSIONS: Coronary cusp vorticity was preserved after David reimplantation, regardless of neosinus creation. Increased retrograde flow and helicity were more prominent in T. David-V patients. These novel magnetic resonance imaging methods can assess the clinical implications of altered aortic flow dynamics in patients undergoing various types of valve-sparing aortic root replacement.     

Results of surgery for aortic root aneurysm in patients with Marfan syndrome

OBJECTIVES: This study was undertaken to examine the long-term results of surgery for aortic root aneurysm in patients with Marfan syndrome. METHODS: Forty-four patients underwent aortic root replacement and 61 underwent aortic valve-sparing operations for aortic root aneurysm. Patients who underwent aortic root replacement had more severe symptoms, worse left ventricular function, more severe aortic insufficiency, and larger aortic root aneurysms than did patients who had aortic valve-sparing operations. Two types of valve-sparing operations were performed: reimplantation of the aortic valve in 39 patients and remodeling of the aortic root in 22 patients. Echocardiography was performed annually during follow-up. The mean follow-ups were 75 +/- 54 months for the aortic root replacement group and 49 +/- 38 months for the aortic valve-sparing group. RESULTS: There were 1 early death and 7 late deaths; 6 deaths were in the aortic root replacement group and 2 were in the aortic valve-sparing group. Survivals at 10 years were 87% in the aortic root replacement group and 96% in the aortic valve-sparing group (P =.3). Freedoms from reoperation at 10 years were 75% in the root replacement group and 100% in the valve-sparing group (P =.1). Freedoms from valve-related mortality and morbidity were 65% after root replacement and 100% after valve-sparing operation (P =.02). Freedom from aortic insufficiency greater than 2+ after aortic valve-sparing operations was 75% at 10 years and was similar for both types of valve-sparing operations; however, the diameters of the aortic annulus and neoaortic sinuses increased only after the remodeling procedure. CONCLUSIONS: This study suggests that aortic valve-sparing operations provide similar survival but lower rates of valve-related complications than aortic root replacement for patients with Marfan syndrome. Reimplantation of the aortic valve may be more appropriate than remodeling of the aortic root to prevent dilation of the aortic annulus, and for this reason we now use only this technique to treat patients with Marfan syndrome.     

Clinical introduction of a novel prosthesis for valve-preserving aortic root reconstruction for annuloaortic ectasia

OBJECTIVE: Most patients with annuloaortic ectasia are young. They are at risk for complications related to a lifetime of anticoagulation when composite grafts containing mechanical valves are used for reconstruction. The majority of patients have near normal valve cusps. Valve-preserving techniques have been developed to maintain valve function and avoid anticoagulation. The eddy currents occurring within the sinuses of Valsalva in the natural aortic root have been shown to be important in the smooth, gradual, and gentle closure of the valve. Compliance of the sinuses is important in reducing stress in the leaflets. A novel ascending aortic prosthesis with "built in" compliant sinuses (Robicsek-Thubrikar graft) was developed for clinical aortic root replacement. METHODS: Woven Dacron tubes were used to make the prostheses. Three precisely measured square pieces were cut to make the expandable, individual sinuses. Sewing the individual neo-sinuses to a scalloped end of the Dacron tube graft created the neo-sinotubular junction and sinotubular ridge. Five patients with annuloaortic ectasia underwent valve-preserving aortic root reconstruction. RESULTS: All intraoperative transesophageal echocardiographic images after the valve-preserving procedure showed a normal appearing root with 10% radial expansion of each sinus in systole. The space between the cusps and neo-sinus wall in systole was normal. No patient has more than mild aortic regurgitation. CONCLUSIONS: Valve-preserving aortic root reconstruction with a novel Dacron prosthesis with compliant "built in" sinuses re-establishes normal aortic root geometry with near normal valve motion. This may enhance the durability of the valve-preserving operation.     

主动脉根部外科解剖及其与毗邻结构关系

目的：测量主动脉根部不同高度的口径大小，并观察主动脉窦与邻近结构的关系。方法：用30例正常成人甲醛固定心脏标本，测量主动脉根部不同高度的口径和主动脉瓣的大小，观察主动脉窦与邻近结构的关系。结果：（1）主动脉窦中部（Sinus)＞主动脉窦管结合部上1cm(STJ1)＞主动脉窦管结合处（STJ0）＞主动脉瓣环基底（Base）。经方差分析检验，P＜0．05，说明主动脉根部4个高度口径大小的差别具统计学意义。（2）主动脉瓣的瓣高、瓣附着缘长和瓣游离缘长的测量结果显示。（3）二尖瓣前瓣中轴线与主动脉窦的关系显示，二尖瓣前瓣中轴线86．6％位于左冠状动脉窦与无冠状动脉窦之间。（4）右心房主动脉隆凸与主动脉窦的关系显示，右心房主动脉隆凸由无冠状动脉窦形成者占73．3％，由无冠状动脉窦和右冠状动脉窦共同形成者占26．7％。（5）左、右肺动脉瓣交界点与主动脉窦的关系显示，左、右肺动脉瓣交界点对向左、右冠状动脉窦之间者占80％。结论：测量结果有助于心外科手术的开展。     

Aortic repair in Marfan's syndrome: prevention of mechanical leaflets damage

Aortic incompetence in Marfan's syndrome results from distortion or dilatation of the sinuses of Valsalva, annuloaortic ectasia or a combination of these problems. Valve leaflets in these patients are macroscopically normal in spite of aortic insufficiency. Replacement of the ascending aorta, root and aortic valve with a composite graft was, for a long time, the treatment of choice for Marfan patients. Valve-preserving procedures (remodeling or reimplantation) provide the advantages of avoiding the shortcomings of standard surgical techniques, and maintaining the functional integrity of the left ventricular (LV) outflow tract, aortic root and ascending aorta. We developed a modified valve-sparing reimplantation technique for avoiding leaflet damage. This was achieved by leaving a 'cushion' of aortic wall (8--10 mm) that, sewn on the Dacron graft, works as a 'damper' and prevents leaflets injury during the systolic opening of the valve. For final judgment of this operative method long-term results are necessary.     

Valsalva prosthesis in aortic valve-sparing operations

Aortic valve-sparing operations have provided very good clinical outcomes. However, the absence of the sinuses of Valsalva might limit valve durability. The Gelweave Valsalva prosthesis, which presents pre-fashioned neo-sinuses, has been designed in order to avoid early leaflets deterioration. We report our results in 63 patients who underwent valve-sparing operations (reimplantation technique) using the Gelweave Valsalva graft. The main indication was ascending aorta aneurysm or annuloaortic ectasia, with or without aortic insufficiency. The operation was performed also in cases of Marfan syndrome, Bicuspid Aortic Valve (BAV), and acute Type A dissection. In-hospital mortality was of 4.7%, and two thirds were acute Type A dissection patients (P=0.01). There were no late deaths. Three years freedom from grade 3-4 AI and freedom from late aortic valve replacement were 91.7+/-4.3% and 93.8+/-5.1%, respectively. Aortic valve-sparing operations show good results in patients electively operated for aortic root ectasia. Aortic cusps repair may lead to late failure. Even if the Gelweave Valsalva prosthesis is easy to implant and it also reproduces pseudosinuses, a long-term follow up is necessary to determine if this graft may reduce leaflets deterioration.     

Opening and closing characteristics of the aortic valve after valve-sparing procedures using a new aortic root conduit

BACKGROUND: The durability of aortic valve-sparing procedures is negatively affected by increased leaflet stress in the absence of normally shaped sinuses of Valsalva. We compared valve motion after remodeling procedures using a standard conduit and a specifically designed aortic root conduit. METHODS: Echocardiographic studies of the aortic valve dynamics were performed in 14 patients after remodeling of the aortic root (7 standard conduits, group A; 7 new conduits, group B) and in 7 controls (group C). Opening and closing leaflet velocities and percent of slow closing leaflet displacement were measured. Root distensibility and the pressure strain of the elastic modulus were measured at all root levels. RESULTS: Root distensibility and the pressure strain of the elastic modulus were different in group A and B only at the sinuses (p < 0.001). Opening and closing leaflet velocities were not different among groups. Slow closing leaflet displacement was markedly more evident in group B patients (24.2%+/-1.9% versus 2.5%+/-1.9% in group A, p < 0.001) and similar to controls (22.1%+/-7.9%). CONCLUSIONS: The new conduit guarantees dynamic features of the aortic valve leaflets superior to those obtained with standard conduits and more similar to normal subjects.     

Mechanisms of aortic valve incompetence: finite-element modeling of Marfan syndrome.

OBJECTIVES: Progressive aortic root dilatation and an increased aortic root elastic modulus have been documented in persons with Marfan syndrome. To examine the effect of aortic root dilatation and increased elastic modulus on leaflet stress, strain, and coaptation, we used a finite-element model. METHODS: The normal model incorporated the geometry, tissue thickness, and anisotropic elastic moduli of normal human roots and valves. Four Marfan models were evaluated, in which the diameter of the aortic root was dilated by 5%, 15%, 30%, and 50%. Aortic root elastic modulus in the 4 Marfan models was doubled. Under diastolic pressure, regional stresses and strains were evaluated, and the percentage of leaflet coaptation was calculated. RESULTS: Root dilatation and stiffening significantly increased regional leaflet stress and strain compared with normal levels. Stress increases ranged from 80% to 360% and strain increases ranged from 60% to 200% in the 50% dilated Marfan model. Leaflet stresses and strains were disproportionately high at the attachment edge and coaptation area. Leaflet coaptation was decreased by approximately 20% in the 50% root dilatation model. CONCLUSIONS: Increasing root dilatation and root elastic modulus to simulate Marfan syndrome significantly increases leaflet stress and strain and reduces coaptation in an otherwise normal aortic valve. These alterations may influence the decision to use valve-sparing aortic root replacement procedures in patients with Marfan syndrome.     

Aortic root reconstruction with preservation of native aortic valve and sinuses in aortic root dilatation with aortic regurgitation.

BACKGROUND: We assessed the results of a modified technique for aortic root reconstruction including preservation of the native aortic valve and sinuses. METHODS: A modified technique for reconstruction of the aortic root was devised in which the native aortic sinuses are preserved and remodeled, the diameter of the sinotubular junction is reduced, the ventriculoaortic junction is reinforced with a Dacron prosthesis, and the coronary ostia are reimplanted. Since January 1995, this modified operative technique was performed in 13 patients with a mean age of 54 +/- 21 years. The median grade of aortic regurgitation was 3; in 10 patients it was caused by dilatation of the sinotubular junction, and 3 had additional annuloaortic ectasia. RESULTS: The aortic crossclamping time was 61 +/- 18 minutes. In-hospital mortality was 2 of 13 (15. 3%) patients, both deaths being related to complications of aortic dissection. In 1 patient aortic regurgitation increased to grade 3, necessitating aortic valve replacement. At a mean follow-up of 2.1 years, the remaining 10 patients had stable aortic valve function with a median grade of regurgitation of 1. The mean New York Heart Association functional class was 1.2. CONCLUSIONS: Aortic root reconstruction with preservation of the native aortic valve and sinuses allows symmetric reconstruction of the aortic sinuses and adaptation of the diameters of the sinotubular and ventriculoaortic junctions, thus optimizing aortic valve function. Moreover, it prevents contact of the aortic valve leaflets with the Dacron graft, which may enhance the durability of the repair.     

Surgery of the dilated aortic root and ascending aorta in pediatric patients: techniques and results.

OBJECTIVE: Dilatation of the aortic root is a well-known cardiovascular manifestation in children and adult patients with connective tissue disease (e.g. Marfan syndrome). Dilatation of the ascending aorta is extremely rare and may be associated with bicuspid aortic valve. This report evaluates the incidence of dilatative aortic root and ascending aortic pathology in patients younger than 18 years and analyzes the results obtained after repair and replacement strategies. METHODS: Between 1/1995 and 12/2002, a total of 752 operations on the thoracic aorta were performed in adult and pediatric patients. We present our experience with a group of 26 patients <18 years of age, who required isolated surgery of the aortic root and/or ascending aorta because of a dilatative lesion. Fifteen patients had isolated aortic root dilatation (13 of them suffered from Marfan syndrome), eight patients presented with an idiopathic dilatation of the ascending aorta and three patients had dilatation in association with a bicuspid aortic valve. Mean age was 10 +/- 4.8 years (4-18 years). Repair of the aortic root with preservation of the aortic valve (Yacoub, David or selective sinus repair) was performed in nine patients, replacement using a homograft was performed in five patients, composite graft with mechanical prosthesis in two patients, with biological prosthesis in one patient and Ross operation was performed in one case. Isolated supracoronary graft replacement was performed in eight patients. RESULTS: Two patients died during hospitalization: a 10-year old girl developed respiratory failure on the 2nd postoperative day and autopsy revealed Ehlers-Danlos syndrome with a massive intrapulmonary emphysema. A 14-year-old Marfan patient with severely depressed preoperative LV function died from low cardiac output following composite-graft, mitral and tricuspid valve repair. One patient required aortic valve replacement 7 days after an aortic valve sparing root repair. There was no additional perioperative morbidity. In the long-term, two patients died from rupture of the thoracic aorta, both following minor non-cardiovascular surgical procedures. Both had normal sized descending and abdominal aorta. CONCLUSION: Repair of the aortic root and/or ascending aorta in children and adolescent patients can be performed with acceptable early and late results. While the presence of severe comorbidity may adversely affect early outcome, long-term survival was mainly determined by rupture of the descending aorta.     

The morphology of the normal aortic valve as compared with the aortic valve having two leaflets

We studied 30 normal aortic valves and 64 aortic valves with only two leaflets to examine their morphologic components. The components of the aortic valve are the leaflets, the sinuses, and the interleaflet triangles. The first part of our study shows the relationship of these component parts of the normal aortic valve to the other cardiac structures. The second part shows a wide variation in the architecture of valves having two leaflets. Having produced criteria for the number of sinuses and the number of leaflets, we discovered that previous criteria used in the definition of valves with two leaflets are inadequate when the whole valvular complex is considered. Only seven valves in the study have two leaflets supported by two sinuses. The evidence points to the other valves having started with three leaflets but becoming bicuspid during either intrauterine or postnatal life.     

Aortic valve sparing operations: an update

Background. Aortic valve sparing operations in patients with ascending aorta and/or aortic root aneurysms have been performed for a decade in our institution. Initially only patients with normal aortic valve leaflets had these operations, but more recently we utilized them in patients with prolapse of a single leaflet and in those with a bicuspid aortic valve. This article is an update on the clinical results of these operations.

Methods. From May 1988 to December 1997, 126 patients with ascending aorta and/or aortic root aneurysms and aortic insufficiency underwent replacement of the ascending aorta with reconstruction of the aortic root and preservation of the native aortic valve. There were 85 men and 41 women, with a mean age of 54 years (range, 14 to 84). Thirty-two patients had the Marfan syndrome; 17 patients had acute and 10 had chronic type A aortic dissection; 23 had a transverse arch aneurysm; 26 had coronary artery disease, and 8 had mitral regurgitation. The aortic valve sparing operation consisted of simple adjustment of the sinotubular junction in 33 patients, adjustment of the sinotubular junction and replacement of one or more aortic sinuses in 60, and reimplantation of the aortic valve in a tubular Dacron (C.R. Bard, Haverhill, PA) graft in 33. Fifteen patients also had repair of aortic leaflet prolapse. Only 4 patients had a bicuspid aortic valve.

Results. There were 3 operative deaths due to cardiac failure. Patients were followed from 2 to 117 months, with a mean of 31. There were 11 late deaths: 7 cardiovascular and 4 from unrelated causes. The actuarial survival was 72 ± 8% at 7 years. Two patients required aortic valve replacement; the freedom from aortic valve replacement was 97 ± 2% at 7 years. Doppler echocardiography revealed absent, trivial or mild aortic insufficiency in most patients; only 9 patients had moderate aortic insufficiency.

Conclusions. Aortic valve sparing operations are feasible in most patients with ascending aorta and/or aortic root aneurysms who have normal or near normal aortic leaflets. The functional results of the repaired aortic valve are excellent, and the repair appears to be durable.     

One-year appraisal of a new aortic root conduit with sinuses of Valsalva.

OBJECTIVES: We evaluate the clinical results 1 year after an anatomic reconstruction of the aortic root in which we used a specifically designed aortic root prosthesis that incorporates the sinuses of Valsalva. MATERIAL AND METHODS: The new aortic Dacron prosthesis has a proximal portion in the Dacron conduit that expands on implantation, creating pseudosinuses. During a 12-month period, 28 patients (mean age 59 +/- 14 years) underwent a Bentall operation (12 cases), a remodeling procedure (7 cases), and a reimplantation procedure (9 cases) with the use of a new aortic root conduit. All patients had aortic root aneurysm with an anatomically normal (for the valve-sparing procedure) or diseased aortic valve (for the Bentall operation). Five patients had aortic dissection and 5 had Marfan disease. The mean follow-up was 6 +/- 3 months. All patients underwent postoperative transesophageal and transthoracic echocardiographic studies. RESULTS: All patients survived and were in good clinical condition at the latest follow-up. Postoperative echocardiography showed a marked reduction in ventricular volumes in all patient groups (P <.0005). In the Bentall group the new prosthesis appeared to reduce the tension on the coronary ostial sutures. In patients undergoing both types of valve-sparing procedures a similar normal anatomy of the aortic root was reconstructed. In the reimplantation group the anulus was smaller than in the remodeling group (P =.01). Patients undergoing the reimplantation procedure had less bleeding and a lower incidence of residual valve insufficiency. CONCLUSIONS: The new aortic root prosthesis allowed the reconstruction of the aortic root anatomy in all types of surgical techniques with low postoperative morbidity.     

The myth of the aortic annulus: the anatomy of the subaortic outflow tract

Surgical repair of the small aortic root is limited in part by the very structure of the outflow tract from the left ventricle. The root is not constructed on the basis of a ringlike annulus supporting the leaflets of the aortic valve. The only truly circular structure within the outflow tract is the junction of the aortic wall with the underlying ventricular structures, themselves partly muscular and partly fibrous. This circular ventriculoarterial junction is crossed by the semilunar attachments of the leaflets of the aortic valve, producing an interlinking arrangement between the expanded aortic sinuses and three triangles of fibrous tissue placed beneath the apexes of the commissures between the valve leaflets. The triangles form extensions of the left ventricle that are related, in part, to the pericardial cavity surrounding the heart. The arrangements of the attachment of the leaflets in malformed valves with two (or only one) effective leaflets are highly abnormal, although these valves are usually produced on the template of three aortic sinuses. The valve with two leaflets rarely gives problems during childhood. In valves producing "critical stenosis", there is usually only one effective leaflet, a condition due to incomplete liberation of two of the anticipated three commissures. Detailed study shows that, in these malformed hearts, the attachment of the leaflets is much more annular than in normal valves, with inadequate formation of the fibrous triangles.     

Aortic root surgery in Marfan syndrome: Comparison of aortic valve-sparing reimplantation versus composite grafting

OBJECTIVE: The objective of this study was to compare the results of aortic valve-sparing reimplantation and aortic root replacement with mechanical valve conduits in patients with Marfan syndrome undergoing operation for aortic root aneurysms.Patients and methods Between March 1979 and April 2002, 119 patients with clinical evidence of Marfan syndrome underwent composite graft replacement with mechanical valve conduits (n = 74) or aortic valve-sparing reimplantation according to David (n = 45). The underlying causes were aortic dissection type A (43 patients) and aneurysms (76 patients). RESULTS: Patients undergoing aortic valve reimplantation were younger compared with patients undergoing composite grafting (28 vs 35 years, P =.002) and had longer intraoperative aortic crossclamp times (125 vs 78 minutes, P <.0001) and extracorporeal circulation times (162 vs 124 minutes, P <.0001). Early postoperative mortality was 6.8% (n = 5) in patients undergoing composite grafting and 0% in patients undergoing aortic valve reimplantation (P =.15). Mean follow-up was 30 months for patients undergoing aortic valve reimplantation and 114 months for patients undergoing composite grafting. Freedom from reoperation and death after 5 years postoperatively was 92% and 89% in patients undergoing composite grafting and 84% and 96% in patients undergoing aortic valve reimplantation (P =.31; P =.54), respectively. Thromboembolic complications or late postoperative bleeding occurred in 17 patients undergoing composite grafting, and an early postoperative event occurred in 1 patient undergoing aortic valve reimplantation. CONCLUSIONS: The results of aortic valve reimplantation and composite grafting of the aortic valve and ascending aorta with mechanical valve conduits are similar with regard to early and mid-term postoperative mortality and to the incidence of late reoperations in patients with Marfan syndrome. The low risk of thromboembolic or bleeding complications favors aortic valve reimplantation in these patients.     

Mechanical stress as cause of aortic valve disease. Presentation of a new aortic root prosthesis

We present an overview of studies on the aortic valve and propose that mechanical stress is a main causative factor in the degenerative valvular disease. In the normal aortic valve, the leaflets have a smooth surface, free of wrinkles and creases, throughout the opening process. This smooth leaflet surface during motion is achieved by the "pull and release" movement of the commissures, which occurs because of the compliance of the aortic root. When the aortic root is stiffened, either by artificial means or by the loss of elasticity due to aging, the leaflet dynamics change significantly. The leaflets develop a significant number of creases and wrinkles during the opening process. In the bileaflet valve, the leaflets develop similar creasing and wrinkling during the opening process. This happens mainly due to the less-than-ideal design of the bileaflet valve and in spite of the compliant aortic root. When the aortic valve is spared using a noncompliant tube graft, a similar phenomenon of leaflet creasing occurs. Because the creasing produces high stresses from bending and buckling, it is damaging to the leaflet tissue and can lead to degenerative and calcific valvular disease. Based on these observations a new aortic root prosthesis with compliant sinuses has been designed for the valve sparing operation.     

In vitro evaluation of a new aortic valved conduit

BackgroundThis study examined whether the presence of a sinus of Valsalva equivalent in the KONECT RESILIA aortic valved conduit (Edwards Lifesciences, Irvine, Calif) improves valve hemodynamics, kinematics, and performance.MethodsA 28-mm KONECT RESILIA aortic valved conduit was used to create an in vitro flow test model, and the same aortic valved conduit model without a sinus section was used as a control. Particle image velocimetry and hydrodynamic characterization experiments were conducted in the vicinity of the valves in a validated left-heart simulator at 3 cardiac output levels. In addition, leaflet kinematics of the valves were determined through en face high-speed imaging.ResultsThe KONECT RESILIA aortic valved conduit model exhibited lower mean and peak transvalvular pressure gradients than the control model at all 3 cardiac outputs. In addition, its leaflets opened more fully than did those of the valved conduit without the sinuses, yielding greater effective and geometric orifice areas. It was found that the presence of the sinuses not only facilitated the development of larger and more stable vortices at the initial stages of the cardiac cycle but also helped to maintain these vortices during the late stages of the cardiac cycle, leading to smoother valve closure.ConclusionsThe KONECT RESILIA aortic valved conduit reproduces the bulged section of the aortic root corresponding to the sinuses of Valsalva. With this Valsalva-type conduit, larger orifice areas were observed, improving valve hemodynamics that may enhance performance.     

The mechanism of opening of the aortic valve.

The mechanism of opening of the aortic valve was investigated in dogs by attaching radiopaque markers to the commissures and the leaflets. Analysis of abnormal cardiac cycles demonstrated that, when the ventricular pressure first equalled the aortic pressure, the intercomissural distances increased 9 percent, and the valve opened with a stellate orifice without forward flow and without a rise in aortic pressure. Further opening of the aortic valve was dependent on forward flow over a narrow range. A new mechanism of aortic valve opening is proposed. This mechanism results in minimal flexion stresses on the leaflets and is important for the longevity of the normal aortic valve. It can occur only if the leaflets arise from an expansile aortic root.