Biomedical subjects

G Thiene

Publications and source records attributed to G Thiene.

At least 163 records · Page 9Linked to original sources

PubMed1993

Long term survival without anticoagulation after aortic valve replacement with a Lillehei-Kaster prosthesis. A case report.

A patient who underwent aortic valve replacement with a Lillehei-Kaster prosthesis developed an early duodenal ulcer requiring suspension of warfarin treatment. Subsequently he was managed without oral anticoagulants, receiving only antiplatelet agents, starting from the third postoperative year. Neither thromboembolic nor hemorrhagic complications occurred but at reoperation, performed almost 20 years later for prosthetic stenosis caused by a fibrous ring, and aneurysm of the ascending aorta, mild fresh thrombus was found on the prosthetic ring. Although the long term outcome of patients with a mechanical aortic prosthesis can occasionally be successful even without long term anticoagulation, such management appears to be justified only in highly selected cases.

Anticoagulants↗

PubMed1993

Emergency surgical treatment of ruptured incompetent mitral valve after percutaneous valvuloplasty.

Of 263 consecutive patients undergoing mitral balloon valvulotomy at the Cardiac Catheterization Unit of Padua University Hospital, six (2.3%) required surgical treatment within 24 hours. The indication for surgery was unstable hemodynamic status due to acute mitral insufficiency caused by the percutaneous balloon valvulotomy. The purpose of this study was to evaluate whether the failure of percutaneous mitral balloon valvulotomy, in this subset of patients, was related to technical problems or was the direct consequence of unfavourable pathologic conditions. Additionally, we evaluated the operative results and clinical outcome of these six patients. The patients were all female with a mean age of 55.7 +/- 14 years (range 38-75 years). Previous surgical commissurotomy was performed in three. The anatomical lesions responsible for the massive regurgitation were tear of the anterior leaflet in two patients and tear of the posterior leaflet in four; rupture of the papillary muscle and/or chordae tendineae were present in five. All patients underwent mitral valve replacement. The elapsed time between the onset of mitral regurgitation and surgery ranged from two to 24 hours (mean 10 +/- 11 hours). There were two hospital deaths (33.3 +/- 21.1%): all surviving patients are alive and clinically well. In conclusion, massive mitral regurgitation following percutaneous mitral dilatation appears to be related to unfavourable pathology of the mitral valve rather than to technical errors. Therefore, careful patient selection is mandatory in order to achieve optimal results. In our experience, adequate and aggressive medical therapy provided sufficient time to prepare for the surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

[Morphofunctional correlations in dilated cardiomyopathies].

The aim of this study was to state whether in patients with dilated cardiomyopathy indices of left ventricular function (i.e. left ventricular end-diastolic and end-systolic volumes, ejection fraction, end-systolic pressure to end-systolic volume ratio, mass to volume ratio, elastic stiffness constant) are related to histologic findings, namely percentage of myocytes, of fibrosis and of interstitium. We have studied 26 patients (18 males and 8 females) aged 13-65 years, who underwent right and left heart catheterization, quantitative angiography, coronary angiogram, and in whom a diagnosis of dilated cardiomyopathy was established. All of them had a biopsy specimen taken from the right aspect of interventricular septum, following the technique of King's College. Histology was automatically evaluated with a computerized system for the percent content of myocytes, of fibrous tissue and interstitium. Correlation with hemodynamic parameters was calculated with the least square method. A significant correlation was found between percentage of fibrosis, left and right ventricular ejection fraction and preload index, and between percent myocytes and right ventricular ejection fraction and duration of disease. Thus, left ventricular function indices do not correlate with percent myocytes, as previously shown: this could be due to the fact that alterations in contractile machinery are due primarily to alterations in cell biochemistry. Moreover, the inverse relationship between myocyte content and duration of the disease may reflect those mechanisms, which tend to perpetuate failure in a dilated heart by increasing subendocardial fibrosis. However, the correlation found between myocyte content and right ventricular ejection fraction may be due to the fact that biopsy specimens were taken from the right ventricle.

Adolescent↗

PubMed1993

Pulmonary atresia, intact ventricular septum, and Ebstein anomaly of the tricuspid valve. Anatomic and surgical considerations.

Pulmonary atresia with intact ventricular septum is a disorder that involves the whole right ventricle. An associated Ebstein deformity of the tricuspid valve is found in 10% of the cases, further complicating the anatomy and the function of the right ventricle. From January 1966 to December 1990, pulmonary atresia, intact ventricular septum, and Ebstein deformity of the tricuspid valve were observed in 11 cases in our institution; four of them were necropsy findings and the remaining seven were patients treated surgically. Of the latter, two were boys and five were girls (age range 1 day to 18 days). Two patients were managed by pulmonary valvotomy, three by systemic-pulmonary artery shunt, and two had a combination of the two. Operative mortality was 57%. Eight hearts were available for morphologic study. All had viscero-atrial situs solitus, D-loop ventricular structure, and normally related great arteries. A correlation between the degree of tricuspid valve dysplasia and right ventricular cavity size was observed in all. Furthermore, in five cases the anterior leaflet of the tricuspid valve obstructed the right ventricle at the ostium infundibuli level. In two of our surgical patients, a protruding anterior tricuspid valve leaflet was identified and excised and both patients survived. Ebstein anomaly of the tricuspid valve further complicates surgical management and outcome of pulmonary atresia and intact ventricular septum. Potential obstruction at the ostium infundibuli level should always be considered during repair. Various degrees of right ventricular inlet dysplasia, always present in this complex, may contraindicate an anatomic correction. In these cases a modified Fontan-type procedure should be considered as a valid surgical option.

Abnormalities, Multiple↗

PubMed1993

[Myocardial infarct and sudden death with angiographically undamaged coronary arteries].

Clinicopathologic findings in two young adults, who complained of ischemic cardiac arrest by ventricular fibrillation and of myocardial infarction complicated by cardiogenic shock respectively, are described. At coronary angiography, coronary arteries appeared normal. In both cases, detailed pathologic examination of the coronary arteries disclosed a focal eccentric atherosclerotic plaque in the proximal descending coronary artery, where selective coronary angiography had failed to reveal filling defects. These observations suggest a more critical attitude in evaluating angiographically normal coronary arteries in patients with myocardial infarction or aborted sudden death, and underline the possibility of arterial lumen stenosis underestimation, especially in the presence of eccentric plaque, with likely compensatory ectasia of the plaque-free wall segment.

Adult↗

PubMed1993

[Juvenile sudden death from spontaneous aortic rupture].

UNLABELLED: In the time interval 1979-1991, 150 cases of juvenile sudden death (< or = 35 years) were studied. Among these, 9 were due to aortic rupture within the pericardial cavity. Two were mycotic and 7 dissecting aneurysms. The latter, all male, age ranging from 17 to 31 years (mean 24), presented the following risk factors: Marfan syndrome in 2, isthmal coarctation associated with bicuspid aortic valve (BAV) in 3, isolated and normally functioning BAV in 2. Histology of the dissected aortic wall showed an equal severity of degenerative changes consisting of elastic fragmentation, cystic medial necrosis and medionecrosis. By reviewing our anatomical collection of dissecting aneurysm we found a 12% frequency of BAV. Taking into consideration that the frequency in normal population of BAV is near 1%, the association between bicuspid aortic valve and dissecting aneurysm should not be casual (p < 0.001). IN CONCLUSION: a) natural history of BAV entails the risk of spontaneous aortic laceration and sudden death in the youth, either in the isolated form or in association with isthmal coarctation; b) the aortic tunica media in these conditions shows an intrinsic structural weakness very similar to that observed in Marfan syndrome, as to suggest a congenital, most probably genetic defect with phenotype expression not only at valve level, but also within the aortic wall; c) aortic dissection occurs nearly ten times more frequently in patients with BAV than in normal population.

Adolescent↗

PubMed1992

Long-term echocardiographic Doppler monitoring of Hancock bioprostheses in the mitral valve position.

Echocardiographic and Doppler studies were performed in 134 patients with a Hancock bioprosthesis in the mitral valve position during a follow-up period of 1 to 216 months. Among the xenografts, 57% were clinically normal and 43% had severe dysfunction. Among the normal bioprostheses, 35% had echocardiographically thickened mitral cusps (> or = 3 mm) with normal hemodynamic function; by setting the lower 95% confidence limit of valve area at 1.7 cm2 these patients had a significantly (p < 0.01) smaller valve area than that of normal control subjects. Evaluation of all thickened normal mitral valves showed the highest incidence of thickening at 9 years after implantation. Valve replacement surgery was subsequently performed in 33 patients with dysfunctioning bioprosthetic and echocardiographic diagnosis was confirmed in 91% of explanted valves (bioprosthetic stenosis 21%, incompetence 46%, and combined stenosis and regurgitation 33%). In 2 valves that were found to be stenotic on echocardiographic examination, a calcium-related commissural tear was also observed at reoperation, and in another, a paravalvular leak was found. Dystrophic calcification, isolated (64%) or occasionally associated with fibrous tissue overgrowth (21%), was the main cause of failure. Pannus was present in prostheses with longer satisfactory function (168 +/- 31 vs 124 +/- 21 months; p < 0.001). Long-term performance was evaluated by the Kaplan-Meier method for up to 18 years of follow-up. Freedom from structural valvular disfunction after mitral replacement was 89% at 6 years, 77% at 8 years, 56% at 10 years, 31% at 12 years, 16% at 15 years, and 15% at 18 years.

Actuarial Analysis↗

PubMed1992

A casual spontaneous mutation as possible cause of the familial form of arrhythmogenic right ventricular cardiomyopathy (arrhythmogenic right ventricular dysplasia).

In a family affected by arrhythmogenic right ventricular cardiomyopathy (ARVC) the familial occurrence was investigated. All 14 members of two generations were investigated carefully, and only 2 (father and one son) members were affected. Both subjects had a massive form of the disease with relevant ventricular arrhythmias. Apart from the limitations of having investigated few subjects, this behavior suggests a genetic mutation appearing in the father and transmitted via an autosomal dominant trait.

Adolescent↗

PubMed1992

The Meadox-Gabbay pericardial xenograft: failure of the unicusp principle.

Durability of a new bioprosthesis, the Meadox-Gabbay unileaflet pericardial xenograft, was evaluated by reviewing a series of 12 patients who received this device in the mitral position from 1983 to 1985. Bioprosthetic failure necessitated reoperation in 5 patients 21, 22, 53, 66, and 81 months after placement. Three patients died of cardiac failure after 31, 52, and 70 months; no postmortem examinations were done. In 2 of the 3 patients, an echocardiographic study had shown signs of valvular dysfunction. Pathological examination of five available explants revealed the presence of redundancy and stretching of the single pericardial leaflet in all of them; in one, this lesion alone caused severe prosthetic incompetence. Other pathological findings included cusp and commissural calcification and commissural tears with or without calcification. Histologic examination and electron microscopy showed intrinsic calcification involving both collagen bundles and cellular debris and various degrees of collagen disruption. In this limited series of patients, the Meadox-Gabbay pericardial xenograft demonstrated various modes of failure that markedly impair its durability and render it unsuitable as a cardiac valve substitute.

Adult↗

PubMed1992

Phenotypic and functional characterization of cytotoxic cells derived from endomyocardial biopsies in human cardiac allografts.

This study was undertaken to characterize the phenotype and function of lymphocytes derived from endomyocardial biopsies in heart transplant patients. To this aim, tissue infiltrating lymphocytes were derived from seven heart transplant patients and were analyzed for the expression of a panel of markers, including CD3, CD4, CD8, CD16, CD56, CD45RA, CD45RO, alpha/beta and gamma/delta T cell receptor, and for their ability to lyse a series of targets, including NK-sensitive K-562 targets, NK-resistant Raji targets, donor related, and unrelated normal splenocytes. Our data show that the majority of cultured lymphocytes expressed the CD3+ phenotype and the alpha/beta T cell receptor. The CD4 and CD8 molecules were heterogeneously expressed among T cell lines tested. Concerning cytotoxic related markers, a significant percentage of cells were CD56+. The evaluation of CD45 isoforms showed that both "naive" and "memory" cells were present among heart TIL. Cytotoxic in vitro studies demonstrated that all our T cell lines showed an efficient cytotoxic machinery when tested against NK-sensitive targets. A marked lysis of donor-related splenocytes was demonstrated in all patients tested. To investigate the role of CD3 and HLA class I molecules in the cytotoxic mechanisms taking place in human heart allograft rejection mechanisms, TIL were assessed for their lytic activity against different targets in the presence of anti-CD3 and anti-HLA class I monoclonal antibodies (mAbs). Although donor-specific cytotoxicity was considerably inhibited by the anti-CD3 mAb, no inhibitory effect was displayed by this antibody on TIL-mediated cytotoxicity against donor-unrelated splenocytes. Anti-HLA class I mAb was able to inhibit both allospecific and nonallospecific cytotoxicity. These data suggest that different types of cytotoxic cells may be propagated from biopsy specimens of heart transplant patients.

Adult↗

PubMed1992

Bicuspid aortic and pulmonary valves in the Syrian hamster.

We studied the conditions of the aortic and pulmonary valves of 153 Syrian hamsters belonging to a single family subjected to high endogamous pressure. Semilunar valves of 143 specimens were examined using a stereomicroscope, and in 5 of these cases a histologic study was also performed. The remaining 10 specimens were studied by means of scanning electron microscopy. In 77 specimens both semilunar valves were normal. The aortic valve was bicuspid and the pulmonary valve was normal in 46 animals, while a normal aortic valve and a bicuspid pulmonary valve occurred in 24. In the remaining 6 specimens both semilunar valves were bicuspid. All bicuspid semilunar valves detected herein showed the same morphotype, namely with the leaflets oriented ventrodorsally. The incidence of these anomalous valves did not significantly differ between sexes. Results of a chi 2-test substantiate that conditions of both outflow tract semilunar valves are independent traits. Thus, concurrence of a bicuspid aortic valve and a bicuspid pulmonary valve in an individual is a random event. The present findings support the assumption that bicuspid aortic and pulmonary valves have different morphogenetic origin, although factors producing a bicuspid aortic valve and those leading to a bicuspid pulmonary valve are not mutually exclusive.

Animals↗

PubMed1992

Clinical profile of concealed form of arrhythmogenic right ventricular cardiomyopathy presenting with apparently idiopathic ventricular arrhythmias.

In 24 subjects presenting with apparently idiopathic ventricular arrhythmias, a final diagnosis of arrhythmogenic right ventricular cardiomyopathy was formulated following global evaluation of the clinical, cross-sectional echocardiography and angiographic findings, and the observation of myocardial atrophy with fibrous-fatty substitution in right ventricular endomyocardial biopsy. All patients had good effort tolerance, and a normal cardiac silhouette. Ventricular arrhythmias with a left bundle branch block pattern were present in 23 cases (sustained ventricular tachycardia, nonsustained ventricular tachycardia, ventricular couplets, and ventricular premature complexes); 1 patient experienced an episode of ventricular fibrillation. A nearly constant electrocardiographic feature was T wave negativity in the right precordial leads. Cross-sectional echocardiography and hemodynamic studies showed that right ventricular impairment consisted only of localized structural and dynamic abnormalities; in a few cases the left ventricle was segmentally involved. Familial occurrence was present in 29% of the cases. No case of sudden death was observed during follow-up. These findings confirm that the concealed form of arrhythmogenic right ventricular cardiomyopathy is a cause of so-called "idiopathic" ventricular arrhythmias in subjects with apparently "normal hearts". Echocardiographic and angiographic investigations may lead to the correct diagnosis.

Adolescent↗

PubMed1992

Enhanced A-V nodal conduction (Lown-Ganong-Levine syndrome) by congenitally hypoplastic A-V node.

The basic anatomical substrate of enhanced A-V nodal conduction, manifesting or not as Lown-Ganong-Levine syndrome, is still a controversial issue. We describe the case of a 34-year-old man who presented episodes of ventricular fibrillation. Electrophysiological studies showed that the AH interval was 55 ms, and increased by only 20 ms at paced cycle lengths of 300 ms; atrial pacing induced atrial fibrillation, with a shortest RR interval of 240 ms. Despite verapamil therapy, this patient died suddenly at home. Histological study disclosed a severe A-V node hypoplasia that was evidently congenital in nature; the rest of the conduction system was normal, and no accessory A-V pathways were present. We suggest that enhanced A-V nodal conduction in this patient was due to the developmental defect in the A-V node; this abnormality caused a loss of specific impulse-delaying function, and thus allowed rapid, unfiltered atrial impulses to reach the lower A-V junction and ventricles.

Adult↗

PubMed1992

Glutaraldehyde-fixed bovine iliac veins used as bioprosthetic conduits: an experimental animal study.

The ideal prosthetic conduit for surgical repair of complex congenital heart disease has yet to be found. Twenty conduits were implanted between the right ventricle and pulmonary artery in growing sheep as follows: four Dacron porcine valve conduits (mean time in place, 142 days); four avalved glutaraldehyde-fixed bovine iliac veins (mean 132 days); and 12 glutaraldehyde-fixed bovine iliac veins containing a porcine valve (mean 180 days). Fifteen conduits were left in place from 167 to 244 days (mean 204 days), and five were explanted earlier (mean 54 days). Pathological study included gross, x-ray, histological, and ultrastructural investigation. Five conduits failed because of infective endocarditis. The valved Dacron conduits showed significant tissue ingrowth and calcification of the valve graft. The valved bovine iliac veins presented calcification at the valve level and vein wall, as well as a valvelike calcific fibrous ridge at the proximal anastomosis with the right ventricle. The avalved bovine iliac veins also presented calcific deposits along the wall and a valvelike calcific ridge at the ventricular anastomosis. Histological and ultrastructural studies of the vein tunica media revealed the phenomena of inflammatory rejection and foreign body reaction with loss of smooth muscle cells (medionecrosis) and fibrotic replacement. In conclusion, bovine iliac veins undergo inflammation with medionecrosis indicating that smooth muscle cell antigenicity is not attenuated by glutaraldehyde fixation.

Animals↗

PubMed1992

Non-atherosclerotic coronary artery disease and sudden death in the young.

OBJECTIVE: To assess prevalence and type of non-atherosclerotic coronary artery disease in young people (< or = 35 years) who died suddenly. DESIGN: A necropsy study of 150 consecutive cases of sudden death (that is, within 6 h of the onset of symptoms). RESULTS: Death was attributed to coronary artery disease in 48 cases: in 16 (33%) of them the disease was non-atherosclerotic. Twelve subjects (eight males and four females, age range 2-35 years, mean 24.2) had congenital anomalies: a deep intramyocardial course in six, origin from the wrong sinus in three, and ostial obstructions in three. Sudden death was the first manifestation of disease in six cases. The other six had a history of palpitation or syncope or both. An electrocardiogram was available in five cases and showed ventricular arrhythmias in four; none had angina pectoris. Stress testing was available in two cases: neither showed any effort-dependent ST-T abnormalities. In six cases sudden death was related to physical exercise. Acquired non-atherosclerotic coronary artery disease was found in four cases: spontaneous coronary dissection in three previously symptom free patients and Kawasaki coronary arteritis in one child who had had acute myocardial infarction. CONCLUSION: One third of the cases of fatal coronary artery disease were non-atherosclerotic with coronary artery anomalies being the most frequent form. Coronary artery anomalies should be suspected in young patients who have symptoms of ventricular arrhythmias without any overt signs and symptoms of ischaemia.

Adolescent↗

PubMed1992

[Controversies in the selection of donors in heart transplants].

The shortage of ideal donor hearts has led to an increasing number of would-be heart transplant recipients who die while on the waiting list: an extension of the classical donor criteria seems necessary to expand the donor pool. In this paper, the major controversies on donor selection are presented, along with the clinical results obtained in cardiac transplantation with donor grafts not complying with standard criteria. The extension of donor age over 35 years is supported by the decreased incidence of coronary artery disease (CAD) in the Western world. In our experience, the number of donors over 40 years has increased steadily, without concomitant significant increase in postoperative short- and medium-term mortality after cardiac transplantation. The relative importance of CAD risk factors in the older heart donor is to be weighed out on a case-by-case basis. The performance of coronary angiography in 90% of the donor grafts over 50 years has led to more accurate selection. ECG minor alterations and ECHO diagnosed dyskynesias are of uncertain significance. Localized infection, transitory hypotension, brief cardiac arrest and thoracic trauma do not necessarily contraindicate heart donation. The importance of donor/recipient weight mismatch over 20% is critical only in face of high pulmonary vascular resistance. Prolonged dopamine infusion above 10 micrograms/kg/min may predict poorer function outcome. From our data, severe donor dysionemia may be very hazardous. In conclusion, our experience demonstrates that extended donor criteria do not compromise short- and medium-term clinical results of cardiac transplantation. Nevertheless, several controversial aspects of donor graft selection remain open.

Age Factors↗

PubMed1992

Durability of glutaraldehyde-fixed pericardial valve prostheses: clinical and animal experimental studies.

Bovine pericardium has been widely employed as a xenograft tissue for the manufacture of bioprosthetic valve substitutes. Early three-leaflet valve models showed poor tissue preservation and shortcomings in valve design, which accounted for tissue wear and prosthesis failure due to cuspal tear. Reducing the number of cusps in the unicusp pericardial valve has proved unsuccessful due to stretching of the single pericardial leaflet with consequent valvular incompetence. The new generation of pericardial xenografts present basic changes in valve design and optimal tissue preservation after industrial processing, with no evidence of leaflet tear at medium term follow up. However, clinical experience is limited and, similarly to porcine xenografts, dystrophic calcification still appears to be a major problem.

Adult↗

PubMed1992

Original expectations of the Hancock valve and 20 years of clinical reality.

The standard (glutaraldehyde-preserved) Hancock porcine bioprosthesis was introduced into clinical practice in order to provide surgeons with a cardiac valve substitute which would be nonthrombogenic and therefore would not require anticoagulation, and would be durable, anatomically suitable, and noiseless. In the present report we have reviewed our long-term experience with Hancock porcine valve recipients in order to verify the original expectations of this bioprosthesis have been met.

Adolescent↗