Valvular heart disease: a perspective

Heart Valves Cross-Linked with Erythrocyte Membrane Drug-Loaded Nanoparticles as a Biomimetic Strategy for Anti-coagulation, Anti-inflammation, Anti-calcification, and Endothelialization

In recent years, valvular heart disease has become a serious disease threatening human life and is a major cause of death worldwide. However, the glutaraldehyde (GLU)-treated biological heart valves (BHVs) fail to meet all requirements of clinical application due to disadvantages such as valve thrombus, cytotoxicity, endothelialization difficulty, immune response, and calcification. Encouragingly, there are a large number of carboxyls as well as a few amino groups on the surface of GLU-treated BHVs that can be modified to enhance biocompatibility. Inspired by natural biological systems, we report a novel approach in which the heart valve was cross-linked with erythrocyte membrane biomimetic drug-loaded nanoparticles. Such modified heart valves not only preserved the structural integrity, stability, and mechanical properties of the GLU-treated BHVs but also greatly improved anti-coagulation, anti-inflammation, anti-calcification, and endothelialization. The in vitro results demonstrated that the modified heart valves had long-term anti-coagulation properties and enhanced endothelialization processes. The modified heart valves also showed good biocompatibility, including blood and cell biocompatibility. Most importantly, the modified heart valves reduced the TNF-α levels and increased IL-10 compared to GLU-treated BHVs. In vivo animal experiments also confirmed that the modified heart valves had an ultrastrong resistance to calcification after implantation in rats for 120 days. The mechanism of anti-calcification in vivo was mainly due to the controlled release of anti-inflammatory drugs that reduced the inflammatory response after valve implantation. In summary, this therapeutic approach based on BHVs cross-linking with erythrocyte membrane biomimetic nanoparticles sparks a novel design for valvular heart disease therapy.

Prediction of Stress Map in Ascending Aorta - Optimization of the Coaxial Position in Transcatheter Aortic Valve Replacement

BACKGROUD

Transcatheter aortic valve replacement (TAVR) can reduce mortality among patients with aortic stenosis. Knowledge of pressure distribution and shear stress at the aortic wall may help identify critical regions, where aortic remodeling process may occur. Here a numerical simulation study of the influence of positioning of the prosthetic valve orifice on the flow field is presented.

OBJECTIVE

The present analysis provides a perspective of great variance on flow behavior due only to angle changes.

METHODS

A 3D model was generated from computed tomography angiography of a patient who had undergone a TAVR. Different mass flow rates were imposed at the inlet valve.

RESULTS

Small variations of the tilt angle could modify the nature of the flow, displacing the position of the vortices, and altering the prerssure distribution and the location of high wall shear stress.

CONCLUSION

These hemodynamic features may be relevant in the aortic remodeling process and distribution of the stress mapping and could help, in the near future, the optimization of the percutaneous prosthesis implantation. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0).

Diamond-like carbon coating and plasma or glow discharge treatment of mechanical heart valves

All mechanical heart valves (MHV) are thrombogenic. Application of surface modification technology to reduce the incidence of thrombus formation on MHV is a novel undertaking. This requires collaboration within the bioengineering and cardiothoracic surgery fields. From reviewing results of recent and past investigations, and our own preliminary study with diamond-like carbon coating (DLC) and plasma or glow discharge treatment (GDT) of MHV, we identify and discuss several potentially beneficial effects that may reduce the extent of valve-related thrombogenesis by surface modification. DLC and GDT may affect the surfaces of MHV in many ways, including cleaning of organic and inorganic debris, generating reactive and functional groups on the surface layers without affecting their bulk properties, and making the surfaces more adherent to endothelial cells and albumin and less adherent to platelets. These different effects of surface modification, separately or in combination, may transform the surfaces of MHV to be more thromboresistant in the vascular system.

Regression of left ventricular dilatation and hypertrophy after aortic valve replacement

The aim of the study was to assess the influence of aortic valve replacement on left ventricular size and muscle hypertrophy according to the type of preexisting valve disease (aortic stenosis, insufficiency or combined disease). The study group consisted of 143 consecutive patients (pts) after aortic valve replacement (109 men, 34 women, mean age 48.1 +/- 10.9 years). Reason for the operation was aortic stenosis in 35 pts, aortic insufficiency in 64 pts and combined disease in 44 pts. Echocardiography was performed before surgery, 1 month and 1 year after operation, and yearly during 5-year follow-up. Transvalvular aortic pressure gradients decreased significantly after valve replacement in all subsets without further changes during follow-up (Pmax (mmHg): from 54.2 +/- 20.7 to 17.9 +/- 9.6 in combined disease pts, from 72.3 +/- 19.9 to 21.6 +/- 14.6 in aortic stenosis and from 34.5 +/- 24.2 to 15.6 +/- 11.3 in aortic insufficiency pts, respectively, P < 0.0005). One year after surgery the diastolic dimension of the left ventricle decreased significantly in all subjects, whereas the systolic dimension only in aortic insufficiency and combined disease pts (from 44 +/- 11.8 to 31.6 +/- 5.4 mm, P < 0.001 and from 41.9 +/- 11.5 to 33 +/- 6.7 mm, P < 0.05, respectively). Further decrease of both diastolic and systolic dimensions was observed only in the aortic insufficiency group. Ejection fraction of left ventricle increased only in combined disease pts (from 51.6 +/- 10% to 56.8 +/- 8.2%, P < 0.05). Wall thickness of the left ventricle decreased 1 year after valve replacement only in the aortic stenosis group and in further follow-up in the aortic stenosis and combined disease group. Normalization of left ventricular size is observed in more than 90% of patients during 5-year follow-up as opposed to left ventricular muscle hypertrophy, regressed only in less than a half of the study population. In patients with aortic valve disease the greatest hemodynamic improvement is observed 1 year after valve replacement. This is expressed by marked reduction of the left ventricular dimensions and wall thickness, without significant improvement of the ejection fraction. Further regression of left ventricle dimensions occurs in patients operated on due to predominant valve insufficiency, whereas regression of left ventricular hypertrophy is observed in patients with preexisting valvular stenosis.

Clinical experience with the CarboMedics valve: early results with a new bileaflet mechanical prosthesis

Between January 1989 and August 1992, 612 CarboMedics mechanical prostheses (CarboMedics, Inc., Austin, Tex.) (295 mitral, 308 aortic, and 9 tricuspid) were implanted in 504 patients: 189 patients had isolated mitral valve replacement, 209 had isolated aortic valve replacement, and 106 had multiple valve replacement. The total follow-up was 1182 patient-years. The hospital mortality rate was 7.4% for mitral valve replacement, 5.3% for aortic valve replacement, and 13.2% for multiple valve replacement. Linearized rates for the different complications for mitral valve replacement, aortic valve replacement, and multiple valve replacement (in events per 100 patient-years) were, respectively, as follows: late mortality, 2.6 +/- 0.8, 1.5 +/- 0.5, and 3.9 +/- 1.3; thromboembolism [correction of thromboembolim], 3.7 +/- 0.9, 3.1 +/- 0.8, and 3.9 +/- 1.3; valve thrombosis, 0.5 +/- 0.3 for mitral valve replacement and 0.4 +/- 0.4 for multiple valve replacement; anticoagulant-related hemorrhage, 2.8 +/- 0.8, 1.9 +/- 0.6, and 2.6 +/- 1.1; nonstructural dysfunction, 1.6 +/- 0.6, 0.8 +/- 0.4, and 3.5 +/- 1.2; and reoperation, 1.1 +/- 0.5, 0.4 +/- 0.3, and 3.1 +/- 1.1. Actuarial estimates of freedom from the different complications for mitral valve replacement, aortic valve replacement, and multiple valve replacement (at 5 years of follow-up for mitral valve replacement and aortic valve replacement and 4.5 years for multiple valve replacement) were, respectively, as follows: overall death, 83% +/- 4%, 89% +/- 2%, and 76% +/- 4%; thromboembolism or valve thrombosis, 88% +/- 3%, 91% +/- 2%, and 86% +/- 5%; anticoagulant-related hemorrhage, 89% +/- 3%, 95% +/- 2%, and 90% +/- 5%; nonstructural dysfunction, 97% +/- 1%, 98% +/- 1%, and 91% +/- 3%; and reoperation, 96% +/- 2%, 99% +/- 1%, and 87% +/- 5%. There were no instances of prosthetic structural dysfunction. The performance of the CarboMedics valve is satisfactory at 5 years of follow-up but thromboembolic and hemorrhagic phenomena are still serious complications of mechanical prostheses.

The treatment of aortic stenosis: is valvuloplasty ever an alternative to surgery?

The desire to extend the principle of balloon angioplasty to cardiac valve disease is understandable and commendable. Aortic valvuloplasty is associated, however, with an excessive complication rate, as reported by the Mansfield Scientific Aortic Valvuloplasty Registry (20.5% overall, including a 4.9% death rate within 24 hours and an additional 2.6% rate within 7 days for a 7.5% 1-week mortality). In contrast, the operative mortality for aortic valve replacement now ranges from 3%-5%, with perioperative complications far less than the one in five associated with valvuloplasty. Even if the two procedures had equivalent morbidity and mortality rates, the high incidence of restenosis (30%-60% range at 6 months) for the balloon technique precludes its widespread use for aortic stenosis. Despite the poor mid- and long-term results for balloon valvuloplasty, the procedure may have limited application in some clinical situations. Indeed, there are patients with concomitant systemic illnesses or advanced age ( greater than 80 years) who would not be good surgical candidates. In particular, valvular balloon dilation may be useful in bridging a seriously ill patient to a condition more favorable for replacement therapy. With few exceptions, however, valve replacement remains the gold standard for treatment of adult aortic stenosis.

Percutaneous balloon valvuloplasty in patients with severe aortic stenosis and low ejection fraction. Immediate results and 1-year follow-up

The efficacy, morbidity, and 1-year follow-up of balloon aortic valvuloplasty in patients with low ejection fraction (less than 40%) were studied on a consecutive series of 55 patients (mean age, 77 years) treated from September 1985 to February 1987. Because of their age (20 patients greater than 80 years old), poor left ventricular function, and associated diseases, 45 patients were definitely not surgical candidates. Balloon dilatation with 15-23-mm diameter balloon catheters decreased the transvalvular gradient from 66 +/- 24 to 28 +/- 14 mm Hg (p less than 0.001) and increased the valve area from 0.47 +/- 0.15 to 0.83 +/- 0.27 cm2 (p less than 0.001). Immediately after dilatation, ejection fraction mildly increased from 29 +/- 7% to 34 +/- 9% (p less than 0.001) in 38 patients who had undergone a second left ventricular angiogram after dilatation. No significant change in the degree of aortic regurgitation was found after the procedure. Three patients died in hospital (femoral arterial complications in two, septicemia in one). Immediate clinical improvement was noted in 80% of the patients. During the follow-up (mean, 11 months), 22 patients died (heart failure in 15 patients, sudden death in five patients, myocardial infarction in one patient, cancer in one patient). Thirty patients survived, 21 with persistent clinical improvement. Repeat cardiac catheterization was performed at 6 months in 20 patients, of whom eight had recurrence of symptoms. Nine patients had restenosis: their hemodynamic indexes had returned to prevalvuloplasty values.(ABSTRACT TRUNCATED AT 250 WORDS)

An emergency physician's guide to prosthetic heart valves: valve-related complications

Serious valve-related complications that occur in patients with prosthetic valves have been discussed. The emergency physician's role primarily is to recognize the high probability that one of these serious complications exists and hospitalize the patient so that rapid definitive diagnoses and therapeutic decisions are not delayed.

Improvement in exercise capacity and exercise hemodynamics 3 months after double-balloon, catheter balloon valvuloplasty treatment of patients with symptomatic mitral stenosis

Clinical status, exercise treadmill performance, and hemodynamics were determined in 24 patients with symptomatic mitral stenosis before catheter balloon valvuloplasty (CBV) and at 3 months follow-up. Hemodynamic determinations at rest showed that mitral CBV performed by the double-balloon technique resulted in significant immediate decreases in mean pulmonary arterial wedge pressure (28 +/- 7 to 16 +/- 5 mm Hg, p less than .01), mean pulmonary arterial pressure (41 +/- 11 to 33 +/- 10 mm Hg, p less than .05), and mitral valve gradient (16 +/- 7 to 6 +/- 3 mm Hg, p less than .01), and significant increases in cardiac output (4.3 +/- 1.1 to 5.0 +/- 1.4 liters/min, p less than .01). Mitral valve area increased from 1.0 +/- 0.3 to 2.2 +/- 0.7 cm2 (p less than .01). The mitral valve area was unchanged (2.0 +/- 0.7 cm2, p = NS) at 3 months. The lower pulmonary arterial wedge pressure, pulmonary arterial pressure, and mitral valve gradient persisted at 3 month follow-up catheterization. Clinical examinations showed that before CBV, 21 of 24 patients were in New York Heart Association functional class III or IV; 3 months after CBV, 22 patients were in class I or II. Before CBV, the mean exercise treadmill time was 5.9 +/- 3.2 min and it had increased to 9.8 +/- 2.9 min (p less than .01) by the 3 month follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of outcome of asymptomatic to symptomatic patients older than 20 years of age with valvular aortic stenosis

A 2-part prospective study was performed to evaluate the clinical outcome of patients with hemodynamically confirmed asymptomatic valvular aortic stenosis (AS). During phase 1, linear regression analysis showed continuous wave Doppler to be highly accurate in predicting catheterization measured peak systolic aortic valve pressure gradients in 101 consecutive patients aged 36 to 83 years (mean 65 +/- 8) with symptomatic AS. During phase 2, 90 additional patients (51 asymptomatic and 39 symptomatic) with Doppler-derived peak systolic aortic valve gradients greater than or equal to 50 mm Hg (range 50 to 132 [mean 68 +/- 19]) were followed for 1 to 45 months. Both groups of patients in phase 2 had similar Doppler gradients and clinical and auscultatory evidence of moderate to severe AS at baseline. Asymptomatic patients were younger (p = 0.01), had higher ejection fractions (p = 0.001) and were less likely to have an electrocardiographic strain pattern (p = 0.01) and left atrial enlargement (p = 0.02). End-diastolic wall thickness, left ventricular cross-sectional myocardial area and estimated left ventricular mass were 18% (p = 0.0001), 20% (p = 0.0008), and 29% (p = 0.002) greater in symptomatic patients. During 17 +/- 9 months of follow-up, 21 asymptomatic patients (41%) became symptomatic. Dyspnea was the most common initial complaint, occurring 2.5 and 4.8 times more often than angina and syncope, respectively. Compared with the 39 symptomatic patients, the 51 asymptomatic patients had a lower cumulative life table incidence of death from any cause (p = 0.002), and from cardiac causes (p = 0.0001) including sudden death (p = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)

Catheter balloon valvuloplasty of aortic and mitral stenosis in adults: 1987

CBV for adults with aortic and mitral stenosis is investigational at the present time and should usually be performed within the guidelines of clinical investigation. The technology is an evolving one with regard to types of catheters and balloons, methods of catheter insertion and placement, and patients and valves that are suitable for and will respond well to CBV. The initial results range from disappointing to excellent and must be kept in perspective. The procedure is clearly a palliative one; ideal results are not being achieved at present. Some of the complications are very serious. Nevertheless, CBV is a most promising catheter interventional technique for patients with valvular heart disease. Proper selection of patients and complete reporting of results is important.

Comparative clinical experience with porcine bioprosthetic and St. Jude valve replacement

From 1976 to 1984, 656 patients underwent aortic, mitral, or double valve replacement with a Hancock or Carpentier-Edwards porcine bioprosthesis (POR; n = 293) or with a St. Jude bileaflet valve (SJ; n = 363). Recipients of the St. Jude valve were of more advanced NYHA class preoperatively, required smaller prosthetic sizes, and more often had associated coronary artery disease necessitating bypass grafting (p less than .05). Despite these differences, POR and SJ recipients demonstrated similar 30-day mortality (7.5 vs 10.2 percent), five-year freedom from embolism (92 +/- 2 percent vs 92 +/- 2 percent), freedom from all valve-related complications (79 +/- 3 percent vs 79 +/- 4 percent), and survival (72 +/- 3 percent vs 71 +/- 3 percent) (p = NS). Structural failures occurred exclusively in POR recipients (3.0-4.5 percent/pt-yr after four years), and endocarditis was more common (1.0 vs 0.5 percent/pt-yr); as a result, the reoperation rate was three times higher in POR than SJ recipients (1.4 vs 0.46 percent/pt-yr, p less than .05). Warfarin-related bleeding (2.5 percent/pt-yr) was the most common complication in SJ recipients, but occurred equally frequently in POR recipients requiring anticoagulation; seven (44 percent) of 16 valve-related late deaths were warfarin-related. In properly anticoagulated patients, the thromboembolic rate was low (2.0 percent and 1.1 percent/pt-yr, POR and SJ); this rate increased significantly in SJ recipients receiving antiplatelet drugs alone (4.2 percent/pt-yr; n = 16) or no anticoagulant or antiplatelet therapy (26.4 percent/pt-yr; n = 18) (p less than .05), but increased only slightly in POR recipients (to 1.5 percent/pt-yr, n = 108, and 2.0 percent/pt-yr, n = 63, respectively). Postoperatively, NYHA class 1 was more often achieved in SJ than POR recipients (60 vs 39 percent, p less than .05), perhaps because of the better hemodynamic performance of the SJ valve. Thus, despite differences in patient selection and the nature of complications observed with each prosthetic type, porcine and St. Jude valves provide similar early and late survival, frequency of embolism, total complication rate, and freedom from valve-related morbidity and mortality after five years of follow-up. Limited durability, susceptibility to infection, and inferior hemodynamics remain drawbacks to use of the porcine bioprosthesis. The necessity for warfarin anticoagulation and the frequency of resultant bleeding complications are the major shortcomings of the St. Jude valve.(ABSTRACT TRUNCATED AT 400 WORDS)

Perioperative acute myocardial infarction after valve replacement

The incidence of fatal acute myocardial infarction (AMI) after valve replacement has decreased with use of cold potassium-induced cardioplegia. Despite this method of myocardial preservation, 12 of 662 consecutive patients submitted to valve replacement had this complication. This study retrospectively analyzes, in those 12 patients, the etiologic profile of fatal perioperative AMI, together with its morphologic aspects. The clinical picture in 11 patients was a refractory low cardiac output state. In only 3 cases was AMI diagnosis confirmed during life. Six patients either had a technical complication or a coronary embolus; in these patients AMI was localized in the vascular bed of a single occluded coronary artery, and its morphologic picture resembled that of usual AMI. The 6 other patients did not have a defined cause for AMI and coronary occlusion was not present. In 4 such patients, there was massive circumferential necrosis, mainly in the subendocardium; comparatively, there was a greater prevalence of hemorrhage, contraction bands and necrosis of the layer of subendocardial cells adjacent to the left ventricular cavity. The findings for this group suggest myocardial necrosis due to cell damage during cardiopulmonary bypass; no predisposing factor for perioperative AMI was identified.

Cardiac valve prostheses: pathological and bioengineering considerations

Cardiac valve replacement with mechanical prosthetic or bioprosthetic devices enhances patient survival and quality of life. Nevertheless, prosthesis-associated complications are frequent and contribute significantly to outcome. Thromboembolic complications are the most important problems in patients with mechanical valves, necessitating chronic anticoagulation in all patients receiving them. In contrast, patients with bioprosthetic valves, composed of chemically treated animal tissues, generally do not require anticoagulants. However, bioprostheses fail frequently by degeneration, especially that involving cuspal calcification. This paper reviews the pathological and bioengineering considerations in the selection of cardiac prosthetic valves and the management of patients who have received these devices. The significance, morphology, and pathogenesis of the observed major complications and other alterations during function are described in detail. Contemporary investigative trends are summarized, including studies of inhibition of mineralization and other degenerative changes in bioprostheses, improved design rigid mechanical valves with pyrolytic carbon occluders and the development of central-flow, flexible polymeric leaflet valves.

Hemodynamic differentiation of pathologic and physiologic stenosis in mitral porcine bioprostheses

Porcine bioprostheses are physiologically stenotic valves. Degenerative calcification leading to pathologic stenosis is an increasingly recognized serious late complication of mitral valve replacement with a porcine bioprosthesis. Hemodynamic differentiation of pathologic from physiologic stenosis is important for identification of porcine bioprosthetic valve dysfunction. In 42 patients with a normal Hancock porcine bioprosthesis (standard model, sizes 27 to 33 mm), mean diastolic flow (65 to 461 ml/s), mean gradient (2.0 to 13.4 mm Hg) and effective orifice area (1.1 to 4.4 cm2) were determined at rest, during epicardial pacing (90, 110 and 130/min) and with isoproterenol infusion. A statistically significant increase in mean gradient occurred with increases in flow and decreases in valve size (p less than 0.05). Effective orifice area increased significantly as flow rate increased and as valve size increased (p less than 0.05). These measurements were compared with those in 16 patients with pathologically confirmed porcine bioprosthetic valve stenosis: 8 patients with reoperation (1.1% per patient-year) 3 to 8.5 years after mitral valve replacement and 8 previously reported abnormal cases. Stenotic failure rate was inversely related to valve size (2.1, 1.4, 0.5 and 0% per patient-year for sizes 27 to 33 mm). Stenotic and normal bioprostheses were not accurately differentiated on the basis of a single value for gradient or effective orifice area. A mathematical model that related flow to the square root of the mean gradient allowed complete separation of stenotic from normal prosthetic valve function, after valve size was accounted for and normal confidence limits were established (r = 0.74 to 0.94, sizes 27 to 33, p less than 0.0001). The effective orifice area-flow relation did not provide accurate differentiation of abnormal from normal function. Thus, normal mitral bioprostheses have significant transvalvular gradients whose magnitude depends on flow. Risk of stenotic failure is increased in the smaller valves, which have a larger gradient at implantation. Differentiation of pathologic from physiologic stenosis cannot be made on the basis of a single value for gradient or effective orifice area. Accurate hemodynamic differentiation is achieved by relating mean gradient to mean diastolic flow rate and valve size.

Cerebral Paecilomyces javanicus infection. An ultrastructural study

A 41-year-old diabetic woman developed Paecilomyces javanicus endocarditis and subsequent cerebral fungal embolism and vasculitis with massive infarction and hemorrhage 6 years after a mitral valve replacement with porcine heterograft. The organism was identified by the culture from the infected brain tissue and aortic valve. Cerebral infection due to fungus Paecilomyces is rare. This report documents the cerebral manifestations of fungus Paecilomyces javanicus and describes for the first time the ultrastructure of such an organism obtained from the infected tissue. Their ultrastructural findings, similar to those described in Paecilomyces farinosus derived from culture, include a double-layered cell wall, a triple unit plasma membrane, abundant cytoplasmic lipid droplets, vacuoles, membranous profiles and septal formation. This report further demonstrates hyphae with packed 50A filaments and granulofibrillary material and features suggestive of intrahyphal hyphae, not previously described in fungus Paecilomyces.

A 6 year experience with the St. Jude medical valve: hemodynamic performance, surgical results, biocompatibility and follow-up

After in vitro testing (confirmed in vivo) of three contemporary valve designs (St. Jude, Björk-Shiley and Carpentier-Edwards) demonstrated that the St. Jude valve possessed the most favorable hydrodynamic performance characteristics, a limited clinical trial was begun in high risk patients who might benefit from a prosthesis with improved hemodynamics. Between March 1978 and March 1984, 419 St. Jude prostheses (157 aortic, 156 mitral and 53 double aortic-mitral) were implanted in 366 patients. Ninety-six percent were in New York Heart Association functional class III or IV preoperatively. Early (30 day) mortality was 10.4% overall, and was lower after aortic (5.7%) or double (7.5%) than after isolated mitral valve replacement (16.0%). Forty-four prosthetic mitral valve recipients with severe ischemic mitral regurgitation experienced a 32% early mortality rate; without this group, mitral valve replacement carried a 10% early mortality rate (p less than 0.01). Multivariate logistic regression analysis confirmed that early death was strongly associated with three preoperative patient characteristics (p less than 0.05): ischemic mitral valve disease, depressed left ventricular function (ejection fraction less than 0.55) and advanced functional class (class IV). Late follow-up (7,055 patient-months, mean 22) was 99.7% complete (1 patient lost). Actuarial survival at 4 years was 80, 80 and 79% after aortic, mitral (nonischemic) and double valve replacement, respectively; in the subset with ischemic mitral regurgitation, actuarial survival was 34% (p less than 0.01). Eighty-six percent of survivors were in functional class I or II.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomic analysis of removed prosthetic heart valves: causes of failure of 33 mechanical valves and 58 bioprostheses, 1980 to 1983

The details of heart valve prosthesis-associated problems are not widely known. This study investigated the etiologies of the failures of 91 valves, 33 mechanical prostheses and 58 bioprostheses, obtained at reoperation (83) or autopsy (eight) at the Brigham and Women's Hospital during the 42-month period from mid- 1980 through 1983, one to 264 months (mean, 72 months) after valve replacement. Analysis was by gross, histologic, radiographic, and microbiologic examination, as well as review of clinical records. Overall causes of failure included paravalvular leak (15 per cent), thrombosis (7 per cent), tissue overgrowth (8 per cent), degeneration or mechanical failure (43 per cent), and endocarditis (19 per cent). Endocarditis and paravalvular leak were equally frequent with mechanical prostheses and bioprostheses. In addition, thrombosis (18 per cent), tissue overgrowth (21 per cent), and structural failure (12 per cent) were all important failure modes for mechanical prostheses. Sterile degeneration was the overwhelming cause of failure for bioprostheses, accounting for the failure of 35 of 58 (60 per cent) of those recovered. Sterile degeneration took several forms: calcification, with or without cuspal tears (27 cases, 47 per cent of bioprostheses; mean, 77 months, range, 44 to 108 months) and cuspal defects without calcification (eight cases, 14 per cent; mean, 59 months, range, eight to 122 months). In general, calcification increased with time after implantation, but the propensity for the mineralization of bioprostheses varied widely among patients. Four torn valves that had been in place for more than six years had radiographically undetectable calcific deposits. The results of this study indicate that paravalvular leak and endocarditis are frequent causes of failure for all valve types. No clear failure mode predominates with mechanical valve prostheses, although some designs have specific inherent limitations. In contrast, degeneration, especially that related to mineralization, is the most important cause of the late failure of contemporary bioprostheses.

Fibrinolytic therapy of St. Jude valve thrombosis under guidance of digital cinefluoroscopy

Fibrinolytic therapy is an alternative to urgent reoperation for patients with St. Jude prosthetic valve thrombosis, but requires an accurate method for repeated assessment of prosthetic function. Since the St. Jude valve is not well visualized by conventional cinefluoroscopy, digital subtraction techniques were developed that improved visualization of the value and allowed assessment of leaflet separation and velocity. A 74 year old woman with prosthetic valve thrombosis 5 years after St. Jude aortic valve placement had an opening angle of 58 degrees (normal range 10 to 13; n = 8) with a maximal opening velocity of 1.37 degrees/ms (normal range 2.46 to 2.93). The closing angle was 125 degrees (normal range 120 to 127) with a maximal closing velocity of 1.38 degrees/ms (normal range 2.24 to 3.60). The patient received 250,000 U of streptokinase intravenously, then 100,000 U/h for 72 hours. Improvement in auscultatory findings occurred at 12 hours; repeat digital cinefluoroscopy showed an opening angle of 20 degrees with a maximal velocity of 2.77 degrees/ms, and a closing angle of 126 degrees with a maximal velocity of 1.91 degrees/ms. Digital cinefluoroscopy 4 weeks after discharge on warfarin and dipyridamole therapy was unchanged. There have been no thromboembolic complications after 6 months of follow-up. Thus, digital cinefluoroscopy is a new noninvasive technique that permits accurate measurement of normal and abnormal St. Jude leaflet function. Intravenous streptokinase dissolution of prosthetic valve thrombosis under digital cinefluoroscopic guidance may be an acceptable alternative to emergency reoperation. The frequency and significance of residual subclinical leaflet dysfunction after fibrinolytic therapy and the indications for elective reoperation require further evaluation.

Clinical and echocardiographic features of isolated severe pure mitral regurgitation

Recent studies have shown that rheumatic heart disease is no longer the main cause of isolated severe pure mitral regurgitation. In this study, we evaluated various clinical and echocardiographic features found in the syndrome of mitral regurgitation. Our data is consistent with recent reports that mitral valve prolapse and coronary artery disease are now the predominant causes of mitral regurgitation and that rheumatic heart disease is a much less common etiology. In addition, our data suggest that clinical evaluation alone is usually very accurate in identifying the correct etiology. Various clinical and echocardiographic features found in the subsets of acute and chronic mitral regurgitation are described. Specifically, patients with acute mitral regurgitation were more likely to have echocardiographic evidence of segmental left ventricular dysfunction and flail mitral valve leaflet. In chronic mitral regurgitation, atrial fibrillation and left atrial dilatation were more commonly present. Echocardiography was found to be more useful in the detection of the complications of coronary artery disease rather than in identifying its presence. Patients with a New York Heart Association classification of IV and those with echocardiographic evidence of an increased left ventricular endsystolic dimension or left ventricular hypertrophy had a worse prognosis.