Aortic valve cusp vessel density: relationship with tissue thickness

OBJECTIVES: The presence of a microvasculature within aortic cusps implies that tissue oxygen requirements exceed the amount deliverable by diffusion from the tissue surfaces alone. For the design of a successful tissue-engineered valve replacement, the effect of diffusion distance (tissue thickness) on oxygen delivery must be considered. We therefore examined in normal aortic valve cusps the relationship between the presence of microvessels and the tissue thickness. METHODS: Thirty porcine aortic valve cusps were excised and examined after cusp microvessels were pressure filled with a carbon particle solution. Cusp images were captured for stereographic vessel density analysis, and cusp thickness was determined with a radiographic technique. Histologic cross-sections were evaluated to determine vessel depth from the cusp surface. RESULTS: Cusp basal regions measured 0.69 to 0.86 mm in thickness, significantly thicker (P =.001) than the rest of the cusp, which measured 0.36 to 0.48 mm. In general a vascular bed was present when cusp thickness exceeded 0.5 mm, with a median value of 5.16 vessels/mm(3). CONCLUSIONS: From published values of arterial wall oxygen consumption and diffusivity, we predicted that the probable maximum oxygen diffusion distance for valve tissue would be about 0.2 mm. This was consistent with our physical findings, which implies that central tissue anoxia is avoided by the capillary bed. An avascular tissue-engineered valve metabolically similar to an aortic valve should therefore not exceed a thickness of approximately 0.40 mm.     

Mitral valve replacement in patients after aortic valve replacement

BACKGROUND: Mitral valve replacement in patients who previously had undergone aortic valve replacement is a technical challenge. The rigid aortic prosthesis limits visualization of the anterior mitral annulus and placement of sutures. METHODS: Reoperative mitral valve replacement was performed in five patients after aortic valve replacement. Two patients underwent resternotomy to allow verification of normal aortic prosthetic valve function. Anterolateral right thoracotomy was used for reentry in the remaining three patients. Exposure of the anterior mitral annulus was accomplished by initial traction on the intact anterior leaflet, with resection of this leaflet only after placement of sutures. RESULTS: All patients survived the surgical procedure and are well 2 to 30 months after operation. In one patient it was impossible to open one cusp of the mitral prosthesis, nor was it possible to rotate the valve. The valve was reimplanted, but sutures were tied only after testing for full free cusp motion. CONCLUSIONS: When appropriate, right thoracotomy incision offers excellent exposure of the mitral valve with minimal dissection. Placement of sutures along the anterior portion of the annulus is facilitated by traction downwards on the anterior leaflet. Full range of motion of the prosthetic cusps should be verified before tying the sutures.     

Successful valve repair in traumatic aortic valve regurgitation

Case 1 was a 20-year-old male who had been involved in a traffic accident and developed aortic regurgitation (AR) eight months later. He was admitted with dilatation of the left ventricle. Transesophageal echocardiography (TEE) showed severe AR with perforation of the right coronary cusp. Case 2 was a 50-year-old male who had fallen from a height four months previously, and was admitted with congestive heart failure due to severe AR. TEE showed severe AR due to rupture of the right coronary cusp. In the former patient, valve repair was performed with a patch of autologous pericardium. In the latter patient, cusp reconstruction was performed with autologous pericardium and the commissural plication technique, achieving successful aortic valve repair.     

Valvuloplasty for aortic valve regurgitation resulting from cusp prolapse

Three adults, 2 with tricuspid aortic valve and 1 with bicuspid valve, underwent valvuloplasty for aortic valve regurgitation resulting from cusp prolapse. Surgical procedures consisted of combined cusp plication by triangular cusp resection and subcommissural annuloplasty. Doppler echocardiography revealed trivial aortic valve regurgitation intraoperatively and less than I/IV at discharge in all cases. After mean follow-up of 15 months, 2 tricuspid aortic valve patients remain I/IV regurgitation and II/IV in the bicuspid patient. Although long-term results remain unclear, our results show that this procedure is feasible and beneficial in patients with aortic valve regurgitation due to cusp prolapse.     

Repair of aortic valve prolapse: experience with 44 patients.

OBJECTIVES: In regurgitant tricuspid aortic valves, cusp prolapse may be isolated or associated with dilatation of the proximal aorta. Newly appearing cusp prolapse can also appear after an aortic valve sparing operation (AVSO) and be responsible for residual aortic regurgitation. In this report, we describe our experience in repairing prolapsing aortic cusps in 44 patients with aortic regurgitation. METHODS: Between 1996 and 2003, 260 patients had aortic valve repair or valve sparing procedures in our department. All patients had peri-operative TEE. Prolapse of one or more of the aortic cusps was identified by TEE and confirmed by careful surgical inspection before and after valve sparing surgery. Forty-four patients with cusp prolapse were identified. Fifteen had an isolated prolapse, with a normal root (group I), 18 had cusp prolapse associated with dilatation of the proximal aorta (group IIa), and 11 had a newly appearing prolapse after AVSO (group IIb). Correction of the prolapsing cusp was achieved by either free edge plication, triangular resection or resuspension with PTFE. This procedure was associated with an aortic annuloplasty in group I, and with AVSO in groups II and III. RESULTS: Post-operative TEE showed AR trivial or grade I regurgitation. At a mean of 23 months follow-up, one patient with recurrent regurgitation required an aortic valve replacement with a homograft. All remaining patients were in NYHA class I or II. Echocardiography confirmed the durability of the valve repair. CONCLUSIONS: Among the common causes of aortic regurgitation, isolated cusp prolapse is frequent and is amenable to surgical repair with excellent mid-term results. In particular, in patents who are potential candidates for AVSO, identification and correction of an associated prolapse, either pre-existing or secondary to the AVSO procedure, may further extend the indications for this technique, increase its success rates and improve its long-term outcome.     

Quadricuspid aortic valve: case reports

Two cases of quadricuspid aortic valve with aortic regurgitation are reported. Case 1, a 66-year-old woman was operated on because of aortic regurgitation, and an aortic valve replacement with a bioprosthesis was performed. When the valve was exposed during the operation, it showed four cusps, three of which were of equal size and one smaller cusp which was interposed between the right and left coronary cusp. Case 2, a 46-year-old man was diagnosed, using echocardiography and aortography before surgery, as suffering from aortic regurgitation because of a quadricuspid aortic valve. During surgery, two larger cusps and two smaller cusps and a displacement of the right coronary artery ostium, (which was placed in a lower position and close to the commissure between the right coronary and the right posterior cusps) were found. The four cusps were excised and replaced by a tilting disc prosthesis. In both cases, the postoperative recovery was uneventful. Using the 24 cases from the literature and two of our own cases, the correlation between the size or the position of the accessory cusp and the occurrence of aortic regurgitation was analyzed. The larger the accessory cusp was, the higher the incidence of aortic regurgitation occurred (p less than 0.05).     

Mitral valve pericardioplasty—a long-term follow-up study

Posterior (17) and anterior (3) mitral cusp pericardioplasties were performed in 20 patients between 6 December 1961 and 10 July 1963. A long-term follow-up study was done in nine patients. In six of these, mitral valvectomy with Starr-Edwards ball valve replacement was required after intervals varying between two years and three months and seven years and three months. In only one of the six cases did the pericardium macroscopically appear normal. In four it was obviously thickened and in two of the four there was also evidence of calcification in the pericardium only. In one of these, calcification was gross, causing complete immobility of the whole 2 × 0·6 in (5 × 1·7 cm) pericardial inlay. In only one of the six cases had the pericardium become larger and thinner and this also was in the only patient with a dilated mitral ring. Only three patients remain with the pericardium as inserted into the posterior mitral cusp between eight years and eight years and eleven months previously, but in all three there is clinical evidence of progressive pathology in the mitral valve. The progressive mitral valve involvement in this series could well have been caused by progression of the pre-existing pathology in the cusps and chordae tendineae but the involvement of the pericardial inlay was much more extensive than that of the rest of the cusp.     

Aortic valve allografts in sheep

Some of the mechnical and biological problems surrounding the use of fresh allograft inverted aortic valves as mitral valve substitutes are described. Certain aspects of the problem have been studied experimentally. In three sheep `fresh' aortic valve allografts were inserted, using cardiopulmonary bypass, into the main pulmonary artery, and were observed from 5 to 7 months after operation. The animals survived normally. Their normal pulmonary valves remained in situ. The technique is described. At subsequent necropsy, macroscopically the valves were found to be free from vegetation, and the cusps were pliable and apparently normal. Microscopically, the supporting allograft myocardium showed necrosis and early calcification. The valve cusp showed hyalinization of collagen, although beneath the endocardium this hyalinized collagen contained moderate numbers of fibroblasts with no evidence of proliferation. The endocardium and arterial intima of the allograft showed evidence of ingrowth from adjacent normal host endocardial tissues. The allograft itself was invested in a loose layer of fibro-fatty tissue, which, in view of the necrotic state of the graft myocardium, could well have been a reparative reaction rather than a homograft reaction. It is concluded that, although the cusps could function normally, the necrosis of the myocardium might in time lead to late failure of the graft. Further studies with the valve inserted at mitral level are indicated.     

Total correction of truncus arteriosus with severe truncal valve insufficiency in neonate]

The prognosis of infants with truncus arteriosus associated with severe truncal valve insufficiency is quite poor. Total correction was successfully performed in a neonate with such a complicated anomaly. The patient was 21 days old female with anuria due to severe congestive heart failure preoperatively in spite of medical treatment. She underwent Rastelli operation and pulmonary artery was reconstructed using autologous pericardial 3 valved conduit. Truncal valve was 4 cusps with the malformed nodular margins and one cusp had cleft. This cleft was closed suturing the cleft cusp and adjacent cusp each other and annuloplasty was added in 4 commissures. She survived and her truncal valve insufficiency was still mild at 2 years post-operative period. Although total correction with truncal valve repair for such a severely ill neonate and young infant with truncus arteriosus as this patient has not been reported, our experience suggests that severe truncal valve insufficiency could be fairly well repaired by valvulo-annuloplasty.     

Design and construction of fascia lata aortic valve prostheses

Current techniques for constructing fascia lata aortic valves result in a valve in which redundant cusp tissue is inadvertently incorporated in the proximal part of the cusp. This alters the flow character of the valve and produces a significant stenosis. An alternative technique, based on the normal anatomy of the aortic valve, is suggested which eliminates this fault. The technique is simple and can be used at the time of operation.     

Decalcification of anterior cusp of mitral valve at marked calcification of aortic valve

Short-term and long-term results of surgical treatment were analyzed in 108 patients with aortic valve disease, complicated significant calcinosis spreading on anterior cusp of mitral valve. Mean age of the patients - 53,5±10,8 years (from 25 to 88 years). All patients underwent aortic valve replacement and decalcification of anterior cusp of mitral valve. Coronary bypass grafting was additionally carried out in 10 cases (from 1 to 5 shunts, 1,9 - in average). Hospital lethality was absent. Functional improvement of mitral valve was observed basing on postoperative echocardiography and remained in long-term period.     

Repair of traumatic rupture of the aortic valve.

Traumatic aortic valve rupture is a rare complication of nonpenetrating cardiac injury and can be caused by a tear or avulsion of the valve. The most common method of treatment has been valve replacement, although valve repair has been successful in a few cases of cusp tear or detachment. We report a case of aortic valve commissural avulsion in which a reparative technique was applied and the natural valve was preserved.     

Ascending aortic aneurysm associated with a quadricuspid aortic valve

We report here a rare case of ascending aortic aneurysm associated with a tricuspitalized quadricuspid aortic valve. A 45-year-old man had a fusiform ascending aortic aneurysm with aortic valve regurgitation. Transthoracic echocardiography revealed grade III aortic regurgitation. Chest computed tomography showed an ascending aortic aneurysm with a diameter of 48 mm. Surgery revealed that the aortic valve was a tricuspitalized quadricuspid aortic valve with an accessory cusp between the right coronary cusp and left coronary cusp.     

Significance of raphe in congenitally bicuspid aortic valve

The decrease of rheumatic aortic regurgitation (AR) is observed due to the relative increase of non-rheumatic aortic valvular diseases since 1980. Among 240 patients who had undergone aortic valve replacement (AVR) including combined valvular diseases up to March 1989, the congenitally bicuspid aortic valve was responsible for AR and stenosis (AS) in 33 patients (13.8%) and were divided according to the presence of a raphe. In the raphe (+) group (n = 15), infective endocarditis (IE) (n = 5), prolapse of the aortic valve, mainly non-coronary cusp (n = 5), and thickening with contraction of cusp (n = 4) were the cause of AR. Calcification of the cusp was seen in 2 older (greater than 59 yrs) patients. In the raphe (-) group (n = 18), IE (n = 2), contraction of cusps (n = 2) in the relatively younger (less than 48 yrs) were the cause of AR. Rest of the patients exhibited severe AS due to the calcification of cusps except a case who showed IE with AR in the calcified cusp. Although not generally recognized, the bicuspid valve with a raphe, less tendency to deposit calcium, is an important cause of pure AR severe enough to warrant AVR. The bicuspid valve without raphe, as already recognized, prones to develop severe calcification and AS in later life.     

Infective endocarditis with destruction of the mitral valve annulus and the left atrial posterior wall after cancer chemotherapy

The case is reported of a 48-year-old man who underwent distal pancreatectomy, splenectomy, and 4 cycles of postoperative chemotherapy for stage I pancreatic cancer, at the age of 47. Four days after completion of chemotherapy, the patient developed high-grade fever (40 degrees C). In addition, on day 10, he developed disturbance of consciousness, followed by symptoms of shock, which led to emergency hospitalization. On day 4 of admission, the patient was diagnosed as having infective endocarditis and severe mitral valve insufficiency, and was started on antibiotic and heart failure therapy. Surgery was performed on day 16 of admission; the mitral valve infection had spread to the valve cusp and ring, and thence to the posterior wall of the left atrium. After excision of the lesions, the patient underwent mitral valve replacement with a collared prosthesis valve and a translocation procedure. The postoperative course was uneventful, and there has been no recurrence of inflammation or paraprosthetic leakage over the year and 6 months since the operation.     

Transpecies heart valve transplant: advanced studies of a bioengineered xeno-autograft

Background. Tissue engineering approaches utilizing biomechanically suitable cell-conductive matrixes should extend xenograft heart valve performance, durability, and growth potential to an extent presently attained only by the pulmonary autograft. To test this hypothesis, we developed an acellular, unfixed porcine aortic valve-based construct. The performance of this valve has been evaluated in vitro under simulated aortic conditions, as a pulmonary valve replacement in sheep, and in aortic and pulmonary valve replacement in humans.

Methods. SynerGraft porcine heart valves (CryoLife Inc, Kennesaw, GA) were constructed from porcine noncoronary aortic valve cusp units consisting of aorta, noncoronary aortic leaflet, and attached anterior mitral leaflet (AML). After treatment to remove all histologically demonstrable leaflet cells and substantially reduce porcine cell-related immunoreactivity, three valve cusps were matched and sewn to form a symmetrical root utilizing the AML remnants as the inflow conduit. SynerGraft valves were evaluated by in vitro hydrodynamics, and by in vivo implants in the right ventricular outflow tract of weanling sheep for up to 336 days. Cryopreserved allograft valves served as control valves in both in vitro and in vivo evaluations. Valves were also implanted as aortic valve replacements in humans.

Results. In vitro pulsatile flow testing of the SynerGraft porcine valves demonstrated excellent valve function with large effective orifice areas and low gradients equivalent to a normal human aortic valve. Implants in sheep right ventricular outflow tracts showed stable leaflets with up to 80% of matrix recellularization with host fibroblasts and/or myofibroblasts, and with no leaflet calcification over 150 days, and minimal deposition at 336 days. Echocardiography studies showed normal hemodynamic performance during the implantation period. The human implants have proven functional for over 9 months.

Conclusions. A unique heart valve construct has been engineered to achieve the equivalent of an autograft. Short-term durability of these novel implants demonstrates for the first time the possibility of an engineered autograft.     

Aortic valve replacement for quadricuspid aortic valve complicated with idiopathic thrombocytopenic purpura; report of a case

An 83-year-old woman, who had suffered from idiopathic thrombocytopenic purpura (ITP), was admitted to our hospital because of cardiac heart failure and chest pain. The platelet was 42 x 10(4) in microl. Echocardiography revealed moderate aortic stenosis and regurgitation and left ventricular dysfunction. Preoperatively, we tapered oral steroid and administered high-dose immunoglobulin intravenously. Intraoperatively, we found quadricuspid aortic valve and the rudimentary accessory cusp was located between the right coronary cusp and noncoronary cusp. Aortic valve replacement was performed with bioprosthetic valve. The postoperative course was uneventful. Postoperative echocardiography revealed no perivalvular leakage. Preoperative administration of high-dose immunoglobulin and intraoperative platelet transfusion is very effective to minimize hemorrhagic complication in patients with ITP. We herein report an extremely rare quadricuspid aortic valve complicated with ITP.     

A case of quadricuspid aortic valve with aortic regurgitation

A 67-year-old man with grade 3 aortic valve regurgitation was found to have a quadricuspid aortic valve. The aortic valve consisted of 1 large, 2 intermediate and 1 small sized cusp. An accessory cusp located between the right and noncoronary cusps, and shaped like a hammock which sling by the fibrous strings originating from the both commissures to the aortic wall. Aortic valve replacement was successfully performed with a 23 mm St. Jude Medical prosthetic valve, and the patient is asymptomatic five months post-operatively. Histological examination of the resected cusps showed fibrous thickening and no rheumatic valvulitis or infective endocarditis.     

Surgical treatment of traumatic rupture of the normal aortic valve

Blunt trauma followed by aortic valvular insufficiency is a rare occurence. In one case, a male high-school student who had sustained a non-penetrative chest injury suffered from aortic regurgitation resulting from the rupture of the normal aortic valve. A sizable tear in the non-coronary cusp caused aortic insufficiency. The case was treated successfully by surgical replacement of the aortic valve with a No. 21 SJM prosthesis.     

Mechanism of venous valve closure and role of the valve in circulation: a new concept

PURPOSE: The purpose of this study was to investigate the blood flow changes and venous wall movements that occur in the perivalvular area during venous flow, to learn how these physiologic events influence the movements of the valve cusps, and to learn how the movements of the valve cusps influence the venous flow. MATERIALS AND METHODS: Twenty healthy volunteers (10 male, 10 female, age 18 to 52) were subjects of this study. Each volunteer was examined in semi-recumbent and standing positions at rest and during active foot movements. Ultrasound examinations were performed in the B-flow mode supplemented by B-mode and pulsed-wave Doppler scanning. RESULTS: Four phases of the valve cycle are described. During the opening phase (0.27 +/- 0.05 s), the cusps move from the closed position toward the sinus wall. After reaching a certain point, the valves cease opening and enter the equilibrium phase. During this phase (0.65 +/- 0.08 s), the leading edges remain suspended in the flowing stream and undergo self-excited oscillations with an amplitude of 0.01 to 0.16 cm. During the closing phase (0.41 +/- 0.07 sec), the leaflets move synchronously toward the center of the vein. The subsequent closed phase has a duration of 0.45 +/- 0.05 seconds when the cusps remain closed. During the equilibrium phase, flow separation occurs at the leading edge of the cusp with reattachment at the wall of sinus. At this point, flow splits into two streams at each valve cusp. Part of the flow is directed into the sinus pocket behind the valve cusp, forming a vortex along the valve cusp before re-emerging in the main stream in the vein. When the valve is maximally open, the two cusps create a narrowing of the lumen about 35% smaller than the vein distal to the valve. In this narrowed area flow accelerates, forming a proximally directed jet. CONCLUSIONS: The valve cusps undergo the four phases constituting the valve cycle. The local hemodynamic events, such as flow separation and reattachment, and vortical flow in the sinus play important roles in the valve operation. In addition to prevention of retrograde flow, the valve acts as a venous flow modulator. The vortical stream behind the valve cusps participates in the operation of the valve, and prevents stasis inside the valve pocket. The central jet possibly facilitates outflow.