Integration of Virtual Learning of Induction Machines for Undergraduates

In context of understanding problems faced by undergraduate students while carrying out laboratory experiments dealing with high voltages, it was found that most of the students are hesitant to work directly on machine. The reason is that error in the circuitry might lead to deterioration of machine and laboratory instruments. So, it has become inevitable to include modern pedagogic techniques for undergraduate students, which would help them to first carry out experiment in virtual system and then to work on live circuit. Further advantages include that students can try out their intuitive ideas and perform in virtual environment, hence leading to new research and innovations. In this paper, virtual environment used is of MATLAB/Simulink for three-phase induction machines. The performance analysis of three-phase induction machine is carried out using virtual environment which includes Direct Current (DC) Test, No-Load Test, and Block Rotor Test along with speed torque characteristics for different rotor resistances and input voltage, respectively. Further, this paper carries out computer aided teaching of basic Voltage Source Inverter (VSI) drive circuitry. Hence, this paper gave undergraduates a clearer view of experiments performed on virtual machine (No-Load test, Block Rotor test and DC test, respectively). After successful implementation of basic tests, VSI circuitry is implemented, and related harmonic distortion (THD) and Fast Fourier Transform (FFT) of current and voltage waveform are studied

Modern Pedagogy Techniques for DC Motor Speed Control

Based on a survey conducted for second and third year students of the electrical engineering department at Maharishi Markandeshwar University, India, it was found that around 92% of students felt that it would be better to introduce a virtual environment for laboratory experiments. Hence, a need was felt to perform modern pedagogy techniques for students which consist of a virtual environment using MATLAB/Simulink. In this paper, a virtual environment for the speed control of a DC motor is performed using MATLAB/Simulink. The various speed control methods for the DC motor include the field resistance control method and armature voltage control method. The performance analysis of the DC motor is hence analyzed

Urologic manifestations of inflammatory pseudotumor: Report of 2 cases and review of the literature.

We report two adult patients with varied urologic symptoms who were found to have inflammatory pseudotumor on histopathology. The first patient had a large, solid, enhancing retroperitoneal mass lesion and presented with increased frequency of urination and recurrent urinary tract infections. The second patient had an obstructing left distal ureteric stricture and presented with painless hematuria. Though preoperative radiological diagnosis of this entity is not feasible, the present article illustrates the imaging findings in this unusual disease entity with review of the relevant literature

Unraveling and Entrapment leading to acute loss of jailed wire and its long term follow-up: case report

Jailed wire technique i.e wiring of the side branch (SB) before main vessel (MV) stenting is recommended to keep it open when the SB is deemed important ( > 2mm). Rarely, it becomes difficult to retrieve the jailed wire behind the stent and it may suffer fracture or entrapment, although exceedingly rare. It may be asymptomatic or can lead to abrupt closure of side branch resulting into periprocedural myocardial infarction. Here, we report a case of 56-old male who had undergone percutaneous coronary intervention (PCI) of proximal left anterior descending artery in 2012 during which jailed balance middle weight wire (BMW, Abott Vascular, USA) of diagonal branch got unravelled and entrapped. As patient was asymptomatic, he was conservatively managed. 6-years later, he suffered acute inferior wall myocardial infarction with complete heart block. Primary angioplasty of totally occluded right coronary artery was done with 3x38 mm Xience prime stent (Everolimus eluting stent; Abott vascular, USA). In coronary angiography of left system, left anterior descending and diagonal branches were completely patent. The fractured and retained jailed wire was still in diagonal branch with no displacement in comparison with previous coronary angiography. The patient was discharged in stable cardiac condition with appropriate follow up advise. To the best of our knowledge, this is the longest follow up of entrapped, and fractured BMW wire

Ostre zapadnięcie się całkowicie rozprężonego stentu III generacji w trakcie przezskórnej interwencji wieńcowej w obrębie rozwidlenia tętnic

Acute stent recoil or radial collapse of a stent is a rare phenomenon leading to subsequent acute stent thrombosis or in-stent restenosis as delayed sequelae. Reduced strut thickness, a larger stent/vessel ratio, and a larger balloon/stent ratio are factors leading to stent recoil. Here, we report a case of acute recoil or radial collapse of Promus Element Plus, a third-generation everolimus-eluting stent with thin stent struts in a 66 year-old male who underwent bifurcation percutaneous coronary intervention of left anterior descending artery (LAD) and diagonal branch (D1). Following kissing balloon inflation at 16 atm pressure after deployment of stents in LAD and D1, acute radial collapse of stent in proximal LAD was noted. It was successfully bailed out by further multiple, short sequential inflations using same size noncompliant balloon. Acute radial collapse probably occurred due to inflation at higher pressure with an oversized balloon, and relatively thin struts of the stent.Ostre zmniejszenie średnicy stentu lub zapadnięcie się stentu to rzadkie zjawisko, którego następstwem jest ostra zakrzepica w stencie lub późniejsze powikłanie w postaci restenozy w obrębie stentu. Czynnikami przyczyniającymi się do zmniejszenia średnicy stentu są mniejsza grubość rozpórek, wyższy współczynnik średnica stentu/średnica referencyjna naczynia oraz wyższy współczynnik średnica balonu/średnica stentu. Autorzy przedstawili przypadek ostrego zmniejszenia średnicy stentu lub zapadnięcia się stentu Promus Element Plus — stentu III generacji uwalniającego ewerolimus, z cienkimi rozpórkami — u 66-letniego pacjenta, u którego wykonano przezskórną interwencję wieńcową w obrębie rozwidlenia gałęzi międzykomorowej przedniej (LAD) i gałęzi diagonalnej D1. Po napełnieniu balonów (jednocześnie użyto 2 balonów — technika kissing balloon) pod ciśnieniem 16 atm i rozprężeniu stentów umieszczonych w LAD i D1 zaobserwowano ostre zapadnięcie się stentu w proksymalnym odcinku LAD. Sytuację udało się uratować, kilkakrotnie napełniając balon w krótkich sekwencjach. Zastosowano niepodatny balon o tym samym rozmiarze. Przyczynami ostrego zapadnięcia się stentu były przypuszczalnie napełnienie balonu o zbyt dużym rozmiarze z zastosowaniem zbyt wysokiego ciśnienia oraz stosunkowo cienkie rozpórki stentu

Intravascular knot as a complication of tortuosity at innominate-arch junction unravelled by counter-clockwise rotation- simple solution to complex problem

Transradial approach scores over transfemoral approach as it is associated with less complications, mortality, and morbidity. Though right sided approach is more convenient for manipulating catheters and devices, aorto-subclavian tortuosity may result into looping, entrapment, kinking, and rarely intravascular knot formation. Here, we describe a case of a 60-year old female which had gone transradial catheterization from right side. Due to aorto-innominate tortuosity, excessive clockwise torque was applied to the catheter to cannulate right coronary artery which resulted into pressure damping, and intravascular knot formation in brachial artery. It was unravelled by counter clockwise rotation of catheter, and thus completing the procedure

Twin Circumflex Coronary Artery with anomalous origin from left main trunk — a rare variant

Coronary artery anomaly in form of dual origin of the circumflex artery is a rare anomaly. Though mostly described as having separate origin, both arising from left main coronary as twin circumflex artery itself has not been reported so far. Here we report a case of 57-year old male patient who had presented with ST elevation anterior wall myocardial infarction. His angiogram revealed left main trunk which was giving a left circumflex artery (LCx). On further coursing, left main trunk was trifurcating into left anterior descending artery (LAD), ramus intermedius and second left circumflex artery. Second circumflex branch was giving larger obtuse marginal branch while right coronary artery was smooth, non-dominant, and normal flowing artery. There was discrete eccentric stenosis with critical lesion in proximal LAD for which patient refused any intervention. Based on angiographic findings, it was diagnosed as a twin circumflex, both arising from left main trunk as one coming before the bifurcation while another after the bifurcation. An extensive search of literature and to the best of our knowledge, such type of anomaly is being reported for the first time

Balloon assisted trapping (BAT) and retrieval of fractured and impacted coronary angioplasty balloon catheter: simple solution to a complex problem

Fracture of catheter fragment in a coronary artery during percutaneous coronary angioplasty is a rare complication, which may result into embolization or impaction leading to complete or near complete occlusion of respective territory, arrhythmia, or rarely sudden death. Here, we report an unusual complication of a broken balloon catheter during angioplasty of a calcified right coronary artery in a 78-year old female which was successfully retrieved by balloon assisted trapping in guiding catheter

Percutaneous Trans Mitral commissurotomy (PTMC) in the background of giant left atrium using Reverse Loop Entry technique

Percutaneous trans-mitral commissurotomy (PTMC) using Accura balloon is an effective procedure for management of patients with rheumatic mitral stenosis. It is not uncommon to come across giant left atrium (LA) especially in the developing world as patient often present late in the course of the disease. This is a technically challenging situation as usual landmark changes which make the procedure difficult beginning from septal puncture to negotiation of balloon into left ventricle across the mitral valve. Here we report a case of 16-year old girl suffering from rheumatic mitral stenosis in which left atrium was giant (13cm x 11cm) where the mitral valve could not be negotiated with standard technique. Valvotomy was successfully executed by reverse loop entry technique

Znaczenie osi koniuszkowo-mitralnej w trakcie przezskórnej komisurotomii mitralnej

The development of acute severe mitral regurgitation (MR) requiring surgery is one of the most dreaded complications of percutaneous transmitral commissurotomy. We present the case of a 29 year-old female with severe rheumatic mitral stenosis whose mitral valve dilatation was performed using an Accura balloon. Once the balloon catheter had crossed the mitral valve to reach the left ventricle, it was facing away from the apico-mitral axis. It was inflated in distal portion, and mitral valve dilatation was done in the usual fashion. She developed acute severe MR. As it was misaligned with the apico-mitral axis, it caused a chordae rupture of the postero-medial papillary muscle which was identified during surgery. We conclude that a misaligned Accura balloon catheter during balloon inflation can pluck the chordae tendinae and can cause acute severe mitral regurgitation, and therefore can unearth the underlying subvalvular pathology.Rozwój ostrej ciężkiej niedomykalności zastawki mitralnej (MR) wymagającej leczenia chirurgicznego jest jednym z najpoważniejszych powikłań przezskórnej komisurotomii mitralnej. W niniejszej pracy przedstawiono przypadek 29-letniej kobiety z ciężką reumatyczną stenozą zastawki mitralnej, u której zwężoną zastawkę poszerzono za pomocą balonu Accura. Po przejściu przez zastawkę mitralną i wejściu do lewej komory cewnik balonowy odchylił się od osi koniuszkowo-mitralnej. Wypełniono dystalną cześć cewnika i poszerzono zastawkę mitralną stosowaną zwykle techniką. U chorej rozwinęła się ciężka MR. Odchylenie cewnika od osi koniuszkowo-mitralnej spowodowało zerwanie struny ścięgnistej tylno-przyśrodkowego mięśnia brodawkowatego, co stwierdzono w czasie zabiegu chirurgicznego. Autorzy konkludują, że nieprawidłowe ustawienie cewnika balonowego Accura w trakcie napełniania balonu może spowodować zerwanie struny ścięgnistej i doprowadzić do ostrej ciężkiej MR, a tym samym ujawnić wadę podzastawkową