Abstract An 34–year–old man presented to the emergency department of our hospital with palpitations and presyncope. He was a smoker but had no others known cardiovascular risk factors. At admission, his electrocardiogram (ECG) showed sustained monomorphic ventricular tachycardia (VT) at a rate of 187 beats per minute. The VT was successfully treated with synchronized direct current cardioversion. The ECG in sinus rhythm showed Qs from V1 to V6 with ventricular repolarization anomalies in the same site suspicious for previous anterior necrosis. A transthoracic echocardiogram revealed akinetic apex, akinesia of middle segments of the interventricular septum, anterior and lateral walls, Left Ventricular (LV) ejection fraction of 30% and a large apical mass suspicious for LV thrombus. The patient was admitted to the coronary care unit and taken to the Cath lab that showed total left anterior descending mid–segment occlusion. Due to the chronicity of the condition, the patient was recommended to optimal medical therapy. Suspecting LV thrombus, the patient began treatment with unfractionated heparin i.v. and subsequently imbricate therapy with enoxaparin s.c. and warfarin. Additionally, the patient underwent subcutaneous implantable cardioverter defibrillator (S–ICD) implantation for secondary prevention of sudden cardiac death. At echocardiographic follow–up one week after discharge, the apical mass remained unchanged despite warfarin therapy with INR at target. For this reason, the patient was recommended to perform a Cardiovascular magnetic resonance (CMR). Three months after S–ICD implantation, a CMR was performed which showed transmural areas of late gadolinium enhancement involving all apical segments and middle segments of the interventricular septum which allowed the diagnosis of a large intramyocardial dissecting hematoma (IDH) of left ventricle. IDH is a rare complication of ST–elevation myocardial infarction (STEMI), it is an unusual form of subacute cardiac rupture and could be fatal. It usually consists of a cavity or channels within the myocardium. Its prognosis varies according to its location, but generally apical IDH have more favorable outcome with a higher likelihood of spontaneous retraction. We report this case because the IDH is a diagnostic challenge and it represents an extremely rare and poorly described event in the literature.

An 44–year–old woman was referred to our hospital for chest pain. She had no known cardiovascular risk factors but had a history of previous acute pericarditis following pregnancy. At admission, she still had chest pain improved by leaning forward. Cardiovascular examination and her electrocardiogram showed nothing pathological. On laboratory tests, there were mild elevation of troponin T and normal C–reactive protein. A transthoracic echocardiogram revealed only a minimal pericardial effusion close to the right heart chambers. A chest X–ray was generally normal. She was admitted to the coronary care unit with a provisional diagnosis of myopericarditis. Three days later, due to the persistence of symptoms despite the appropriate pharmacological therapy, it was decided to perform coronary angiography. During the procedure, selective cannulation of the left coronary artery was not possible, and a non–selective injection disclosed no coronary artery arising from the left coronary sinus. On selective injection of the right coronary sinus, a single ostium was visualized. The right coronary artery (RCA) was a great vessel, with no stenosis. A left anterior descending artery (LAD) and left circumflex artery (LCx) were perfused from RCA collateral vessels, both without lesions. Coronary computed tomography angiography confirmed a single coronary artery with its ostium in the right sinus of Valsalva and agenesis of the left main artery (LCA). A physical stress echo ruled out inducible myocardial ischemia. Coronary artery anomalies are rare congenital disorders that are usually diagnosed incidentally. Single coronary artery (SCA) has been known since 1903. It is an anomalous condition in which the SCA originates from a single aortic orifice, either the left or the right aortic ostium, and gives rise to the entire coronary circulation. Isolated congenital SCA is a very rare condition, occurring in 0.024–0.098% of the general population. Right SCA with congenital absence of the LCA is the least common type of SCA, and is extremely rare with a reported incidence of 0.0008%. SCA has been reported in association with atherosclerotic disease, coronary artery fistulas, mitral valve prolapse, bicuspid aortic valves, tetralogy of Fallot, transposition of the great arteries, hypertrophic cardiomyopathy and Takotsubo syndrome. We report this extremely rare case because the concomitant association with pericardial diseases has never previously been reported.

An 38–year–old man was referred to our hospital for chest pain. He was a smoker but had no other cardiovascular risk factors and had no history of relevant diseases. On cardiovascular examination, a rough grade IV/V systolic murmur was present at the mesocardium. His electrocardiogram showed sinus tachycardia and complete right branch block. On laboratory tests, cardiac biomarkers were negative. A transthoracic echocardiogram showed left ventricle cavity–sized at the upper limits with preserved systolic function and mild concentric hypertrophy. The aortic root was ectatic with tricuspid valve and mild regurgitation. In addition, there was a great spheric cavity in the region of the right sinus of Valsalva that was communicating with the aortic lumen with turbulent flow inside. The Pulmonary Trunk was dilated and there was a strange turbulent flow within it that extended towards the aortic valve. A chest computed tomography (CT) scan was performed in emergency which ruled out an aortic dissection and revealed the presence of an aneurysm of the right sinus of Valsalva. The following day, a transesophageal echocardiogram was performed which confirmed the aneurysm of the right sinus Valsalva and the presence of systodiastolic flow between it and the right ventricular outflow compatible with a fistula. For this reason, the patient was transferred to the Cardiac Surgery Department of another hospital. He underwent cardiac surgery of resection of aneurysmatic tissue, direct suture of the fistula by the combined transaortic / transpulmonary route and reductive plastic surgery of the pulmonary trunk. Aneurysms of sinus of Valsalva are rare cardiac anomalies, which may be either acquired or congenital. A congenital lack of continuity between the aortic media and annulus fibrosis may initiate aneurysm formation. Acquired aneurysms may result from trauma, endocarditis, syphilis, Behcet, Marfan’s syndrome and senile–type dilatation. In our case, the etiology of the aneurysm is not well understood. It could be a congenital aneurysm that has fissured over time creating a fistula with the right ventricular outflow. This fistula caused a significant left–to–right shunt resulting in haemodynamic changes such as pulmonary trunk dilation. We report this case because the concomitant presence of an aneurysm of the right Valsalva sinus and a fistula between it and the right ventricular outflow represents an extremely rare and poorly described event in the literature.

In this article, friction stir welded T-joints of innovative dissimilar aluminum alloys have been produced and tested with the aim to investigate the feasibility of using this joining technique, in this configuration, in the aerospace field with the final aim to save weight. The introduction of both this new welding technique and innovative alloys, such as AA 2198 and AA 6056, could allow making lighter and stronger structures. Some experiments, carried out previously, have shown that the fixturing device, the tool geometry, and the tilt angle play a significant role in the joint soundness. A wide experimental characterization has been carried out on FSW T-joints of AA 6056 T4 extrudes to AA 2198 T3 rolled plates. The results attained allow to put in evidence some critical issues on the investigated configuration and can be considered as a further acquired knowledge in the understanding and the design of friction stir processes.

La Friction StirWelding (FSW) e una delle tecniche di giunzione piu interessanti per l’industria aeronautica poiche, essendo un processo di saldatura allo stato solido, permette di superare tutti i problemi conosciuti collegati alle trasformazioni di fase dei processi di giunzione allo stato fuso. Tale tecnica, inoltre, permette di ridurre il peso nelle aerostrutture se comparate a quelle ottenute mediante la tecnologia del rivettamento. In questo lavoro viene presentata una caratterizzazione meccanica di un componente ottenuto con tecnologia FSWmediante giunzioni sovrapposte (lap). Il campione simula un pannello bulkhead, ossia un pannello che separa un ambiente pressurizzato di un aeromobile (ad esempio la cabina) da ambienti non pressurizzati (ad esempio la stiva). Tali pannelli (skin) sono usualmente irrigiditi da parti estruse rivettate sul pannello stesso (stringer). In questo caso le parti estruse, con una sezione a forma di T, sono state giuntate al pannello tramite FSWcon configurazione lap sui due lembi di appoggio. Le condizioni di carico sono state scelte per simulare due condizioni operative reali: tensione circonferenziale (hoop stress) e trazione perpendicolare al piano difissaggio (T-pull). I risultati permettono di apprezzare il buon comportamento atteso dal simulatore. Una caratteristica specifica delle giunzioni in configurazione a sovrapposizione (FSWLap), ossia il difetto ad uncino (hook defect), gioca un ruolo significativo nelle rotture osservate durante i test statici e nel fenomeno di innesco delle cricche durante i test ciclici. I risultati indicano che l’attenzione dovrebbe essere focalizzata sul settaggio dei parametri di processo al fine di minimizzare il verificarsi dell’hook defect.

Friction Stir Welding is a young solid state joining technology that, invented and patented at The Welding Institute (TWI) of Cambridge (UK) in 1991, has been showing many potentialities. Due to the interesting features of FSW, lots of research activities have been carried out all over the world, on different materials (aluminium alloys first of all, but also steel, titanium, magnesium, copper, polymers, etc.) and for different geometries, even if the most investigated one is, without any doubt, the butt joint configuration. Other geometries, such as lap joint, even if potentially very interesting, have been less studied. In the present paper, attention has been focused on joints simulating a geometrical configuration used in aircraft structures to manufacture bulkhead panels. The aim is to exploit the feasibility of substituting rivets with a friction stir weld. An AA 2024 T351 T shape extruded stringer was overlap friction stir welded to an AA 2056 T3 clad rolled sheet (see Table 1 for chemical compositions) by means of two parallel beads, as illustrated in Figure 1. The principal welding process parameters adopted are: rotational speed of 400 RPM, welding speed of 100 mm/min and tilt angle of 3 degrees. It is important to put in evidence that the two beads were one by one welded with the same rotational verse and welding direction. Static and dynamic tests were carried out in two different loading conditions. The first loading condition, named "hoop stress", simulates the pressurization of the cylindrical fuselage with a load applied to the skin, perpendicularly to the stringer; the second loading condition, named "T pull", simulates the pulling action of stringer on the skin. On the basis of the experimental characterization carried out, the following conclusion can be drawn: FSW appears to be a suitable welding technology to make sound lap joints of extruded parts on rolled sheets. The obtained overlap friction stir welds resulted free of distortions and appreciable defects. Static mechanical properties in hoop stress loading way are very high compared to the skin parent alloy. The joint mechanical efficiency resulted close to one. Static mechanical properties in T-pull loading appear very high if compared with those provided by conventional riveted joints. Fatigue properties are fully governed by the hooking material in the advancing side of beads: this defect plays a significant role in the crack initiation both upon T-pull and hoop stress loading. Its significant role is present at every fatigue stress level, even if the failure modes can be significantly different. As a consequence, much care should be put in setting the process parameters and in designing the tool geometry in order to minimize the hook defect occurrence. Probably an important role, in hook defect occurrence, is played by skin cladding layer too.

The effect of process parameters on mechanical and microstructural properties of AA 2139 T8 joints produced by friction stir welding (FSW) was analysed by means of statistical tools. Three different parameters were taken into account: angular speed ( ω), welding speed ( va), and plunging depth ( p); each of them was varied on three levels. Forces and temperatures achieved during the welding were monitored and analysed for all joints. An accurate microstructural analysis was performed: the occurrence of some remarkable defects, typical of FSW, such as tunnel or lack of penetration, was related to actual process parameters adopted. The extension of each FSW characteristic zone was measured and the main grain dimension within each of these zones was measured. The mechanical properties of the joints were evaluated by means of Vickers microhardness measurements and tensile tests at room temperature. It was observed that the joint welded with lowest angular speed, highest welding speed, and greatest plunging depth attained the best performances. The statistical data treatment allowed providing a numerical model capable of predicting the mechanical performances of joints.

Aluminum alloys are widely used in the aircraft industries even if such materials present lower ductility with respect to steels, anisotropy phenomena and, more important, they are often "difficult" to be welded or even "non-weldable". In the last years the friction stirwelding process (FSW) was proposed and applied in order to get good mechanical and technological performances of the joints.In this paper, an experimental and numerical investigation on the lap joining of AA2198-T4 aluminum alloy blanks by FSW is presented. In particular the joints strength and metallurgical properties are investigated by varying the joint configuration and the tool geometry and rotational speed. It is found that the use of cylindrical-conical pin tools and the correct choice of the relative sheet positioning increase the welded nugget extension and integrity improving the mechanical performances of the obtained joints. (C) 2009 Elsevier B.V. All rights reserved

Laser beam welding, of light alloys has always represented a big challenge for both designers and technologists due to the large number of process parameters to take into account and the variable responses of the different materials to be welded. In this paper the results of experimental research on laser beam welds of innovative heat treatable aluminum alloys is reported. The well known T geometry (a stringer welded to a skin) has been considered. Two different skins have been analyzed: AA 2139 and AA 6156, both in form of rolled sheets. Two different stringer have been analyzed: AA 2139 and PA 765, both in form of extruded parts. AA 4047 has been used as filler wire. In the first part of the paper, all the steps leading to the realization of sound welds will be described. The criteria used in order to assess the soundness of a weld was the absence of defects, such as cracks or large pores, verified by means of NDE. In the second part of study, both micro structural analysis and mechanical characterization of welds will be described and discussed. Conclusions will demonstrate the importance of the influence of chemical composition of the parts, above all stringer. The performance of the best welds, however, were very close to those of parent materials.