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At least 919 records · Page 51Linked to original sources
PubMed2006

Is the degeneration of aortic valve bioprostheses similar to that of native aortic valves? Insights into valvular pathology.

Aortic stenosis (AS) is the most common valvular disease requiring valve replacement with a prevalence of 2-4% in adults greater than or equal to 65 years of age. There is increasing evidence that AS is an active inflammatory process that is highly regulated, displaying multiple hallmarks of atherosclerosis. Clinically, the definite therapy of advanced AS is prosthetic valve replacement. Herein, bioprosthetic tissue valves (BPs) possess superior thromboresistant and hemodynamic properties compared with mechanical valves. However, cusp degeneration and calcification also limit their long-term outcome. The pathogenesis of BP calcification as well as that of native valves is still poorly understood. Recent studies suggest a similar valvular pathology, that underlies both types of valvular degeneration, but also an even more important role of inflammatory and repair processes in the case of BP degeneration.

Aortic Valve↗
PubMed1993

Aortic valve pressure gradients in patients with aortic valve stenosis: quantification with velocity-encoded cine MR imaging.

OBJECTIVE: Pressure gradients across the aortic valve due to stenosis of the valve must be measured accurately to evaluate the functional severity of the stenosis. Velocity-encoded cine MR has been used to quantify blood flow and flow direction and, more recently, the regurgitant fraction in aortic regurgitation. The purpose of this study was to determine the feasibility and accuracy of velocity-encoded cine MR for estimating pressure gradients across the aortic valve in patients with aortic stenosis. SUBJECTS AND METHODS: We used velocity-encoded cine MR to measure flow velocity and determine pressure gradients across the aortic valve in 19 subjects. The pressure gradient (delta P) was estimated from the simplified Bernoulli equation by using the maximum instantaneous aortic jet velocity (Vmax): delta P (mm Hg) = 4V2max (m/sec). RESULTS: Maximum and mean systolic pressure gradients determined by using velocity-encoded cine MR were 3-148 mm Hg and 2-87 mm Hg, respectively, for all subjects. The pressure gradients correlated closely with gradients determined by using established methods: Doppler echocardiography and cardiac catheterization. Correlation coefficients (r) were .96 (y = 0.94x - 1.9) and .97 (y = 0.97x + 0.5), respectively. CONCLUSION: We conclude that velocity-encoded cine MR imaging provides a noninvasive and accurate means for quantifying the severity of valvular aortic stenosis. MR is a feasible method for determining pressure gradients across the aortic valve.

Adult↗
PubMed1993

Two-dimensional echocardiography for prediction of aortic valve prosthesis size. A comparative study of Medtronic-Hall and Carpentier-Edwards supra-annular valves.

To assess the value of two-dimensional echocardiography (2D ECHO) for predicting prosthetic aortic valve size, the diameter of the aortic annulus was measured before implantation of a Medtronic-Hall valve in 24 patients and a Carpentier-Edwards supra-annular valve in 34. In the Medtronic-Hall group, the average prosthesis size was similar to the average annulus diameter, i.e. 23.2 +/- 2.1 vs 23.0 +/- 3.4 mm (NS), 95% confidence interval for the difference -1.0-0.7 mm. In the Carpentier-Edwards group the corresponding figures were 23.5 +/- 2.1 and 22.0 +/- 2.3 mm (p < 0.001), with 95% confidence interval 0.9-2.0 mm. Correlation between annulus diameter indicated by preoperative 2D ECHO and prosthesis size was stronger in the Medtronic-Hall (r = 0.88, p < 0.001) than in the Carpentier-Edwards group (r = 0.73, p < 0.001). The authors conclude that prosthetic aortic valve size may be accurately predicted by 2D ECHO, with Medtronic-Hall valve size similar to, and Carpentier-Edwards prostheses on average 1-2 mm larger than the 2D ECHO-estimated annulus diameter.

Adult↗
PubMed1976

Actuarial comparison of Hancock porcine and prosthetic disc valves for isolated mitral valve replacement.

From July 1970 through December 1974, 109 patients underwent isolated mitral valve replacement (MVR). A Harken prosthetic disc valve (DVR) was used in 53 patients and glutaraldehyde-preserved Hancock porcine xenograft (PVR) in 56 patients. The functional class, distribution of mitral valve pathology, and incidence of atrial fibrillation were similar in both groups. There were no operative and three (5.5%) late deaths in the PVR group and two (3.8%) operative and ten (19.5%) late deaths in the DVR group. Anticoagulants were not used in the PVR group; there were 3 nonfatal emboli (10%), all occurring in patients with atrial fibrillation and large left atria. Although anticoagulants were used there were 14 emboli (five in patients who died, nine nonfatal) in the DVR group (26.4%). In our experience, there is a significant reduction in morbidity and mortality, primarily from a reduced risk of thromboemboli, if a porcine valve is used for MVR. Anticoagulants should be used in patients with atrial fibrillation and enlarged left atria regardless of the type of valve used.

Adult↗
PubMed2000

[Hemodynamic assessment of the Carpentier-Edwards pericardial valve compared with the St. Jude Medical valve in the aortic position using dobutamine-stress echocardiography].

To assess the hemodynamic performance of the prosthetic valve in the aortic position, we examined dobutamine-stress echocardiography (DSE) to the patients underwent AVR with CEP valve or SJM valve. In 23 mm size, there were no significant differences between CEP group and SJM group in Peak velocity of the aortic jet (PV), peak pressure gradient (PPG) and effective orifice area (EOA). On the other hand, in 21 mm size, PV and PPG of the CEP group were significantly lower than those of the SJM group after DSE. The EOA of the CEP group was significantly larger than that of the SJM group after DSE. Our results suggest that the hemodynamic function of the CEP valve is superior to that of the SJM valve especially in small aortic annuli.

Aged↗
PubMed2001

Aortic valve replacement combined with endoventricular circulatory patch plasty (Dor operation) in a patient with aortic valve stenosis and severe ischemic cardiomyopathy.

A 58-year-old woman with ischemic cardiomyopathy and aortic valve stenosis, underwent aortic valve replacement and simultaneous endoventricular circulatory patch plasty (Dor operation). She underwent coronary artery bypass grafting for severe triple vessel disease 10 years ago. Recently she started to show severe congestive heart failure. Aortic valve stenosis with pressure gradient of 85-mmHg was also found. Coronary bypasses were all patent, but the left ventricle (LV) was severely dilated (LVDd/Ds=71/61 mm) and the ischemic cardiomyopathy was considered as the cause. She successfully underwent aortic valve replacement and endoventricular circulatory patch plasty. The initial postoperative course was complicated with intractable ventricular arrhythmia, but subsequent course was smooth and the patient was discharged with improved symptoms (NYHA Class II). Postoperative catheterization showed decreased left ventricular volume and improved contractility. This case implies the role of LV remodeling procedure in the ischemic cardiomyopathy combined with aortic valve lesion

Aortic Valve Stenosis↗
PubMedDate not supplied

[Is the tricuspid valve an enigma? Surgical treatment: valvuloplasty or valve change? Which prosthesis?].

An extensive review of the literature on the diagnosis and surgical treatment of the tricuspid valve is presented. As a result of this research, it is evident that a satisfactory diagnostic procedure for this valve has not yet been achieved, as is the case with the other cardiac valves; thus, doubts remain regarding the specific indications for surgical treatment. Nevertheless, there exists some consensus among the most experienced specialists on the possibilities of surgery, particular by in determining whether the injury is organic or not. Different groups accept that when the problem is insufficiency by dilatation of the ring, surgery should be conservative. However, if a serious organic injury is found, substitution by a bioprosthesis may be the first option. Only if the valve injury is too severe, or in special cases, like in young patients with a long life expectancy, the use of mechanical valves would be indicated.

Cardiac Surgical Procedures↗
PubMed2002

Tissue engineering of cardiac valve prostheses II: biomechanical characterization of decellularized porcine aortic heart valves.

BACKGROUND AND AIMS OF THE STUDY: For both young patients with congenital heart disease and young, growing adults there is a need for replacement heart valves that will develop with the patient. Tissue-engineered heart valves coupled with in-vitro recellularization have this potential. One approach is to use acellular tissue matrices, but the decellularization treatment must not affect the biomechanical integrity of the valvular matrix. This study investigated the effect of 0.03% (w/v) and 0.1% (w/v) sodium dodecyl sulfate (SDS) on the mechanical integrity of porcine aortic valve leaflets. METHODS: Left coronary porcine leaflets were treated with SDS (0.03% or 0.1%, w/v) in hypotonic or isotonic buffer and buffer alone. SDS in hypotonic buffer produced accellularity. Circumferential and radial specimens of treated leaflets were subjected to uniaxial tensile testing, and the effect of the buffer on leaflet morphology was assessed. Whole porcine aortic roots were also treated with 0.1% (w/v) SDS and subjected to function testing. RESULTS: SDS treatment significantly increased extensibility of the leaflet specimens, which was greater in the circumferential than radial direction. This was seen as a significantly decreased slope of both the elastic and collagen phases of the stress-strain behavior. The ultimate tensile strength and transition stress were not affected significantly; nor was there any significant difference between hypotonic buffer and hypotonic buffer + SDS treatments. Study of the leaflet morphology suggested that the increased extensibility was due to shrinkage as well as to increased hydration of the treated leaflets caused by the hypotonic buffer. CONCLUSION: SDS treatment produced a more extensible tissue with equal strength compared with the fresh aortic valve. Functionality experiments with SDS-treated whole aortic roots showed complete valve leaflet competence under physiological pressures (120 mmHg) as well as physiological leaflet kinematics.

Animals↗
PubMed2004

Mechanical valve prosthesis is a valid option for aortic valve replacement in the elderly.

BACKGROUND AND AIM OF THE STUDY: Thromboembolism and hemorrhage related to anticoagulation remain a major concern in elderly patients with mechanical valves. Clinical results following isolated aortic valve replacement (AVR) with tilting disk and bileaflet prostheses in patients aged over 70 years were analyzed and compared with results in patients aged <45 years. METHODS: Between January 1980 and August 2002, 319 consecutive older patients (group A) and 497 young patients AVR. Preoperative clinical data, early and late mortality, valve-related complications and data related to anticoagulation status (including mean INR and mean interval between INR assays) were compared between groups. RESULTS: Hospital mortality was lower in group B (3.4%) than in group A (10.7%; p <0.0001). Twelve-year actuarial survival was lower in older patients (54% in group A versus 78% in group B; p <0.001). The two groups showed similar 12-year actuarial freedom from hemorrhage (99.6% versus 99.5%; p = 0.69), endocarditis (99.6% versus 98.43%; p = 0.25) and perivalvular leak (99.6% versus 97.9%; p = 0.21). However, actuarial freedom from thromboembolism was lower in older patients (98.8% versus 99.7%; p = 0.041). CONCLUSION: Despite lower rates of long-term mortality and thromboembolism (the latter because of advanced atherosclerosis) in group A, there were no differences in rates of other valve-related complications. Hence, older age cannot be considered a contraindication to implantation of mechanical valves in the aortic position.

Adult↗
PubMed1992

In vitro closing behavior of the St. Jude Medical heart valve in the pulmonary position. Valve incompetence originating in the prosthesis itself.

We examined the in vitro closing behavior of the St. Jude Medical heart valve, simulating (1) a low-pressure system, (2) the anatomic peculiarity of the right ventricular outflow tract and the main pulmonary artery, and (3) disturbed diastolic compliance of the right ventricle. The variables in the experiment were the load impedance to the pump and the valve orientation. The results were as follows. The sequence of closure of the two semidiscs was based on the valve orientation; reduction in impedance caused the semidisc that closed last to remain open, while the other semidisc continued its open-close motion; further reduction in impedance prevented the semidisc, which continued its open-close motion, from closing completely. These results highlight the forces involved in semidisc closure and the existence of a threshold of force for completion of semidisc closure. Further, the results demonstrate that under certain circumstances the threshold cannot be exceeded via those forces. Therefore this incompetence must originate in the prosthesis itself. In this regard, we suggest an urgent need to reconsider the indications for St. Jude Medical heart valve pulmonic implantation. Finally, we advocate the necessity for an in vitro assessment of valve prostheses in a low-pressure system, to evaluate the safety of right-sided placement.

Evaluation Studies as Topic↗
PubMed2005

A valve replacement technique for heavily calcified mitral valve and annulus.

Severe mitral annular calcification is frequently encountered in patients with chronic renal failure requiring dialysis. The procedures are described for the implantation of mitral prostheses in two dialysis patients with mitral stenosis who exhibited heavily calcified mitral annuli. In both cases the calcifications extended around the entire mitral annulus as well as the valve leaflets, papillary muscle, atrial wall and ventricular myocardium, making it impossible to secure prosthetic valves to the mitral annuli. Before implantation, the calcification was partially debrided ultrasonically, and an 'atrioventricular channel' created. A mechanical valve with a polyester fabric collar was fixed on the atrial side of the calcified annulus using double sutures and gelatin-resorcin-formol glue. Perivalvular leakage, obstruction of valve opening or tortuous movements of prosthetic valve ring were not observed, and neither patient developed heart failure after surgery. This technique represents a potentially useful approach in the surgical treatment of patients with severely calcified mitral annuli.

Calcinosis↗
PubMed2005

[Construction of a tissue-engineered valve with decellular porcine aortic valve scaffold in the abdominal aorta of canine].

OBJECTIVE: To explore an experimental method for construction of tissue-engineered heart valve (TEHV) in canine abdominal aorta. METHODS: The decellular porcine aortic valve (PAV) leaflets seeded with canine vessel interstitial cells and endothelial cells (ECs) were implanted into 6 canine abdominal aortas. Valve specimens were obtained respectively at the end of 4, 6, 8 and 10 weeks after implantation were studied for morphology, histology and immunohistochemistry. RESULTS: (1) After 4 weeks implantation, multiple layers of cells grew into peripheral portion of valve scaffold, while new extracellular matrix appeared, and original scaffold tissue was partially absorbed. (2) At the end of 10th week after implantation, the decellular PAV scaffold disappeared completely and was substituted by recipient cells and new extracellular matrix. The interstitial cells in matrix was mainly consisted of fibroblasts and myofibroblast. The matrix was mainly composed by type I, III collagen, some elastic fibers with neutral and acid mucopolysaccharide. (3) Surface of valve leaflets were covered with endothelial cells. CONCLUSIONS: (1) TEHV is primarily constructed with recellularized PAV after implantation into canine abdominal aorta for 10 weeks. (2) Heterotopic implantation into the abdominal aorta is an alternative experimental procedure to study the TEHV.

Animals↗
PubMed1990

Estimation of shear stress-related blood damage in heart valve prostheses--in vitro comparison of 25 aortic valves.

The hemodynamics of heart valve prostheses can be reproducibly investigated in vitro within circulatory mock loops. By measuring the downstream velocity and shear stress fields the shear stresses which are clinically responsible for damage to platelets and red blood cells can be determined. The mechanisms of damage and the effects of shear stresses on blood corpuscles were investigated by Wurzinger et al. at the Aerodynamics Institute of the RWTH Aachen. In the present study, the above data are incorporated into a mathematical correlation, which serves as a basic model for the estimation of blood damage. This mathematical model was applied to in vitro investigations of 25 different aortic valve prostheses. The results were compared to clinical findings. In most cases agreement was good, indicating that this model may be directly applied to the clinical situation. This new method facilitates the estimation of clinically expected blood damage from in vitro measurements. It may be useful for the development and evaluation of new valve prostheses. By comparative evaluation of different valve types it also provides additional information to help the implanting surgeon select the optimum valve for his patient.

Aortic Valve↗
PubMed1979

Valve replacement for Ebstein's anomaly of the tricuspid valve.

The role of valve replacement in the treatment of Ebstein's anomaly of the tricuspid valve remains controversial. Between 1965 and 1977, five patients with Ebstein's anomaly ranging in age from 11 to 57 years (mean 29) underwent tricuspid valve replacement in our institution. All of the patients were cyanotic but one, three were in Functional Class III, and two were in Class IV (New York Heart Association classification). The valve was placed above the coronary sinus. Plication of the atrialized portion of right ventricle was required in only one patient. Four patients had additional closure of an atrial septal defect. There were no deaths. On follow-up (range 1 to 13 years), four patients are in Functional Class I and one is in Class II. None is cyanotic. Four patients are in sinus rhythm and one has a pacemaker because of postoperative complete heart block. We conclude that valve replacement and, when necessary, plication of the atrialized right ventricle produce excellent clinical improvement.

Adolescent↗
PubMed1981

Tetralogy of Fallot with absent pulmonary valve. Should valve insertion be part of the intracardiac repair?

Thirteen patients with complex of tetralogy of Fallot and absent pulmonary valve were treated. Three infants presented with severe cardiorespiratory distress (Group I) necessitating surgical intervention in two and intensive medical treatment in the third; there were no late survivals. The remaining 10 patients were operated upon electively at an older age (Group II); in six the ventricular septal defect was closed and the right ventricular outflow obstruction relieved (Group IIA), and in the other four a valve was inserted at the pulmonary anulus at the time of intracardiac repair (Group IIB). There was no hospital mortality in Group II. Five of the six patients in Group IIA remained symptomatic postoperatively, and three needed a subsequent pulmonary valve insertion. All patients in Group IIB were symptom free following operation; one patient began having a progressive decrease in exercise performance, decrease in pulmonary artery size, and cardiothoracic ratio were more marked in those patients who had primary insertion of a pulmonary valve. The clinical results and postoperative assessment of cardiac function tend to indicate that pulmonary valve insertion should be performed at the time of the intracardiac repair.

Adolescent↗
PubMed1981

Preliminary results in mitral valve replacement with St. Jude medical prosthesis: comparison with the Björk-Shiley valve.

The clinical improvement and the hemodynamic performance at rest and during bicycle exercise in 22 patients 1 year after implantation of a St. Jude Medical mitral valve (SJMM) were compared with the results of 40 patients after implantation of a Björk-Shiley mitral valve (BSM). In both subjective and functional improvement were significant. In the SJMM group no thromboembolic event occurred, while five patients in the BSM group suffered from embolism during the first year postoperative year (12.5%). Hemolysis was significantly lower in the BSM group but remained subclinical in the SJMM group. This may be explained by a premature backward movement of the posterior leaflet of the SJMM prosthesis in the late diastole, which resulted in a change of flow pattern. Low resistance to blood flow in the SJMM prosthesis could be verified by a small diastolic transvalvular gradient. In valves with equal tissue annulus diameters (29 mm), the calculated effective valve orifices were significantly different (3.07 +/- 1.36 cm2 in SJMM, 1.85 +/- 0.53 cm2 in BSM). In both groups, the mean pulmonary artery pressure was significantly reduced at the time of reinvestigation but increased during exercise. Durability may become a problem because of the two moving parts of SJMM, but we have observed no malfunction. The SJMM appears to be a good alternative in mitral valve replacement.

Adult↗
PubMed1995

A rare complication of mitral valve replacement: sudden cardiac death for immobilization of disc valve by an unraveled suture.

Disc immobilization caused by an unraveled suture in a mitral valve prosthesis represents a rare extrinsic complication in heart valve replacement. We report a case of a 54-year-old white male who underwent mitral valve replacement because of a severe mitral regurgitation. A Björk-Shiley tilting disc was implanted with interrupted "U" shaped 3/0 silk sutures. There were no complications and the patient was discharged in the 10th postoperative day. Twenty days after surgery the patient died for acute pulmonary edema. Autopsy revealed an unraveled suture producing interference with the tilting disc as a cause of disc prosthesis immobilization in closed position. The possible explication of this rare complication is the combination between unraveled suture and the pleating held by Teflon sewing ring after restoring heart function. A flaccid heart can produce an overestimation of the annulus size and the valve ring can bring an anomalous interference with the valve mechanism. In conclusion disc immobilization by an unraveled suture is a complication that can occur very rarely but an accurate prevention must be warrant particularly with a tilting disc more than a beleaflet prosthesis.

Death, Sudden, Cardiac↗
PubMed1993

[Aortic valve replacement for narrow aortic ostium, supraannular insertion at noncoronary sinus with Bjrk-Shiley valve].

Fifteen patients with small aortic annuli underwent aortic valve replacement either isolated or combined with other procedures. All patients had aortic valve replacement with Björk-Shiley prosthesis larger than the aortic annulus. The prosthesis was sutured in a supraannular position in the area corresponding to the noncoronary sinus. There was no hospital and late death. In the long term follow up, 21 mm prosthetic gradients by doppler method ranged from 17 to 43 (29.9 +/- 7.3) mmHg in patients with supraannular aortic valve replacement and from 20 to 45 (27.4 +/- 7.1) mmHg in patients with standard aortic valve replacement, which showed statistically no significant difference. Because this technique allows the insertion of prosthetic valves one sizes larger than the size of aortic annulus, it will produce stable hemodynamic result. As a consequence, those procedure such as transannular patch reconstruction will be avoided.

Adult↗