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Biomedical subjects

G Thiene

Publications and source records attributed to G Thiene.

At least 271 records · Page 15Linked to original sources
PubMed1986

Experimental evaluation of porcine-valved conduits processed with a calcium-retarding agent (T6).

The effectiveness of a water-soluble C-12 alkyl sulfate (T6) (U.S. Patent No. 4,323,358) in retarding bioprosthetic calcification was evaluated in 23 porcine-valved conduits (13 T6-treated conduits and 10 controls) implanted in young sheep between the right ventricle and the pulmonary trunk. The grafts were divided into three groups according to the period of function: Group I, less than 2 months; Group II, 2 to 4 months; and Group III, 5 to 7 months. In Group I (four T6 and four controls), endocarditis occurred in five cases. In Group II (three T6 and three controls), four conduits showed severe fibrous peel ingrowth. In Group III (six T6 and three controls), fibrous peel was the main feature in four conduits and calcium deposits occurred in the porcine aortic wall in all cases, with cusp involvement in two; in both T6-treated and control conduits, chemical analysis showed a much lower calcium content of the cusps (8.45 +/- 80 versus 2.95 +/- 1.52 mg/gm dry weight, respectively) than that reported in other animal or human explants. The grade of calcification in control and T6-treated conduits was equal on x-ray analysis, and no differences in calcification patterns were noted on electron microscopy. This experimental model shows a low degree of cusp calcification and no significant differences between T6-treated and control conduits. Peel formation markedly interferes with performance of the porcine-valved conduit. The results of this analysis indicate that valved conduits are not the optimum model for evaluating calcium-retardant agents in biological valves.

Animals↗
PubMed1985

Radiation-induced coronary obstructive atherosclerosis and sudden death in a teenager.

An 18-year-old woman, affected by Hodgkin's disease and treated successfully with radiotherapy, died suddenly. The postmortem study showed an acute septal myocardial infarction in the presence of a severe focal atherosclerotic lesion of the anterior descending coronary artery. This suggests that radiation may contribute to the early development of coronary artery disease.

Adolescent↗
PubMed1985

Broncho-atrial discordance. A clinically diagnosed case.

Determination of the arrangement of the atrial chambers ("atrial situs") is the first step in sequential chamber analysis of complex congenital heart disease. Although bronchial pattern, as detected by chest X-ray, is an excellent guide for prediction of atrial arrangement, exceptions to this rule based on post-mortem examination have been described. We report a case in which discordance between the atrial arrangement (mirror-image) and bronchial morphology (usual) was diagnosed during life.

Bronchography↗
PubMed1985

The surface measurement of aortic atherosclerosis: critical survey and comparison with histologic findings.

Both the reproducibility of the surface measurements of aortic atherosclerosis and the agreement between gross inspective and histologic changes were evaluated. Aortas from male broad breasted white turkeys were chosen because of the high incidence of spontaneous and typical atherosclerotic lesions in this animal strain. Ten male turkeys were killed at 33 weeks of age. The aortas were removed including the iliac bifurcation and stained with Sudan III. Each aorta was processed blindly by four pathologists and a computerized planimeter to determine normal areas, sudanophilic areas and areas covered by plaques. The analysis of variance showed significant differences among the four pathologists' measurements of sudanophilic areas (P less than 0.01) and areas covered by plaques (P less than 0.001). The coefficients of variation among the four determinations made by one pathologist on the same aorta were 3.6% for total aortic area; 10.08% for sudanophilic area; 47.6% for the area covered by plaques. On each aorta histology was performed at the level where all the four pathologists recorded the same findings at inspection, namely a normal area, a sudanophilic area, and an area covered by plaques. Important discrepancies occurred between findings at inspection and those of histologic examination: the ten areas classified as "normal" by all the four pathologists at inspection were shown at histologic examination to be normal in only two cases. In one case a musculo-elastic layer and in seven cases a fibro-elastic layer were found. The ten areas classified as "sudanophilic" by all the observers showed a fibro-elastic layer in five cases, a musculo-elastic layer in two cases and normal findings in three cases. The ten areas classified as "covered by plaques" displayed a typical atherosclerotic plaque in all cases but one. In conclusion, our data indicate that the reproducibility of gross inspective methods is low. Important discrepancies exist between findings at inspection and histologic examinations. The relevance of these findings remains to be established as far as the assessment of human atherosclerosis is concerned.

Animals↗
PubMed1985

Electrophysiologic and histopathologic correlations in a case of permanent form of reciprocating tachycardia.

A case of permanent junctional reciprocating tachycardia with post-mortem documentation of an accessory atrioventricular pathway as the substrate of the arrhythmia is reported. Tachycardia had lasted for 15 years and showed a retrograde P wave (P') and R-P' longer than P'-R interval. The tachycardia circuit utilized a concealed posterior septal accessory pathway as the retrograde limb. Because the arrhythmia was disabling and unresponsive to pharmacological treatment, the patient underwent closed chest ablation of the His bundle. After the procedure, no anterograde or retrograde conduction over the normal conduction system was observed; anterograde conduction over the anomalous pathway showed decremental properties. Because of previous myocardial infarction, the patient developed a ventricular aneurysm and died suddenly 5 months after His bundle ablation. Histological examination of the heart revealed a group of tiny fibromuscular bundles joining the lower rim of the coronary sinus outlet to the summit of the interventricular septums; the anomalous atrioventricular connection pursued a sinuous, tortuous path. The geometrical disposition of the accessory pathway may have been responsible for the decremental properties of conduction observed during life.

Atrioventricular Node↗
PubMed1985

Ultrastructural substrates of dystrophic calcification in porcine bioprosthetic valve failure.

Calcific degeneration is the main cause of porcine bioprosthetic valve failure. This dystrophic phenomenon has been studied by transmission electron microscopy in 26 explants; six normally processed unimplanted xenografts and a pig aortic valve from the slaughterhouse served as controls. Loss of endothelial lining and proteoglycans were a regular finding in all the commercially processed valves. In order to detect initial calcifications, we investigated in particular areas apparently devoid of mineralization at x-ray. Three main ultramicroscopic features were found: 1) intracytoplasmic and interstitial calcospherulae in 22 explants, 2) calcified collagen fibrils in 15, and 3) platelike calcium deposits upon amorphous material in 3. X-ray diffraction and energy-dispersive microanalysis identified Ca2+ deposits as crystals of hydroxyapatite. From these findings there is evidence that debris and membrane fragments of the pig cusp cells represent one of the initial nuclei of calcification.

Animals↗
PubMed1985

[Double-outlet right ventricle with intact interventricular septum. Case report, review of the literature and proposed pathogenetic interpretation].

Double Outlet Right Ventricle with intact ventricular septum is an extremely rare malformation. Only nine cases are recorded in the known world literature. A new case is reported, concerning a female infant six months old when first seen, and still alive after atrial septectomy. The anatomical studies in Double Outlet Right Ventricle suggest that only the Ventricular Septal Defect in the outlet septum is an integral part of the malformation and can be defined as "typical". In more than 10% of cases the Ventricular Septal Defect opens into the inlet or trabecular-muscular portions of the septum: these latter locations of the defect should therefore be considered as "associated". Double Outlet Right Ventricle with intact ventricular septum can be interpreted as the variant lacking both typical and associated Ventricular Septal Defect. From the analysis of anatomical descriptions of the ten known specimens of Double Outlet Right Ventricle with intact Ventricular septum, the Authors word out the hypothesis that ventricular septum closure could be referred to a well developed bulbo-ventricular fold (bulbo-ventricular fold synonimous of cono-ventricular flange and bulbo-atrio-ventricular ledge), as a consequence of missed or defective conal absorption. They conceive a range including on one hand the Subarterial Ventricular Septal defect (bulbo-ventricular fold poorly developed due to effective conal absorption), on the other hand the Restrictive Ventricular Septal Defect and Intact Ventricular Septum (bulbo-ventricular fold well developed due to defective conal absorption).

Female↗
PubMed1985

Results of reoperation for primary tissue failure of porcine bioprostheses.

Results of reoperation for primary tissue failure of porcine bioprostheses were evaluated in 574 patients discharged from the hospital from 1970 to 1981. A total of 413 had undergone isolated mitral valve replacement and 161 isolated aortic valve replacement. Through March, 1984, 88 patients (15%) had required reoperation: 59 had undergone mitral and 29, aortic valve replacement. Primary tissue failure was the main cause of bioprosthetic dysfunction; it occurred in 64 patients (46 mitral and 18 aortic) at a mean postoperative interval of 93 +/- 4 months (range 34 to 158). During the same period, 11 patients required reoperation for bioprosthetic endocarditis, 11 for paravalvular leak, and two for thrombosis. These patients are not included in this review. Reoperation for primary tissue failure was performed after a mean interval of 72 +/- 6 months (range 38 to 158) for patients with aortic bioprostheses and after 101 +/- 5 months (range 34 to 153) for those with mitral bioprostheses (p less than 0.05). Overall mortality at reoperation was 12.5%: 11% for the mitral group and 16% for the aortic group. In 62 patients (45 mitral and 17 aortic) primary tissue failure was caused by calcification of the cusps, associated with severe fibrous tissue overgrowth in seven. Bioprosthetic failure was caused by an intracuspal hematoma in one patient with mitral valve replacement and by lipid infiltration of the cusps in one patient with aortic valve replacement. Actuarial freedom from bioprosthetic primary tissue failure at 12 years is 61% +/- 5% for the mitral group and 69% +/- 7% for the aortic group. On the basis of our long-term follow-up of patients after mitral or aortic replacement with a porcine bioprosthesis, we conclude: primary tissue failure is the most frequent indication for reoperation in patients with a porcine bioprosthesis; calcification of the cusp tissue is the leading cause of primary tissue failure; reoperation for primary tissue failure may be a major concern, although mortality for elective cases is low; and the limited durability of porcine bioprostheses suggests their use be restricted to selected patients.

Animals↗
PubMed1985

Evidence of reduced atherosclerotic lesions in broad breasted white turkeys treated with oxprenolol.

Male Broad Breasted White Turkeys (BBWT) are naturally hypertensive and prone to develop atherosclerosis. Hypertension is characterized by high levels of circulating and tissue catecholamines; atherosclerosis affects mainly the aorto-iliac tract. To evaluate the effect of a beta-blocker on both hypertension and atherosclerosis, 2 groups of BBWT were studied. First group: 12 BBWT treated from the 8th week of age with daily p.o. placebo; second group: 6BBWT treated from the 8th week with 2 mg/kg p.o. daily oxprenolol. Blood pressure (BP) and heart rate (HR) were periodically measured with an indirect method. Seven and 5 BBWT of the first group were sacrificed at 24 and 51 weeks respectively. The 6 animals of the second group were sacrificed at 51 weeks. No significant difference in mean BP and HR values was found between the two groups of animals. On the contrary the oxprenolol treated group displayed a significant reduction in extent and severity of the atherosclerotic lesions. These results seem to substantiate that oxprenolol might positively interfere with the setting of atherosclerosis in these animals independently of BP reduction. One possible explanation could be a direct effect of oxprenolol on the arterial wall.

Aging↗