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There is also a segmentation anomaly at T7–T9 with poorly formed intervertebral discs (arrowhead) cheapest generic carbamazepine uk muscle relaxant in spanish. Extrinsic compression of the thecal sac and spinal cord order carbamazepine 100mg without prescription muscle relaxants yahoo answers, which are compressed and displaced away from the tumour discount carbamazepine 400mg visa muscle relaxant cyclobenzaprine. The tumour is contained within the undisplaced thecal sac but compresses and displaces the spinal cord. There is a fuid–fuid level (arrow) in the metastasis due to bleeding within the tumour. The tips of the cerebellar tonsils extend through the foramen magnum (dashed line) to reach the level of C2. Spine 397 can present with upper limb sensory disturbance and lower limb weakness. Transverse myelitis and multiple sclerosis Transverse myelitis is an infammatory condition of the spinal cord which is usually associated with progressive neurological dysfunction depending on the tracts affected in the cord. In multiple sclerosis, cord lesions will often be associated with white matter plaques in the brain. Similarly, Imaging techniques the position of a fracture should never be assessed from a single view (Fig. Plain radiographs Plain radiography in skeletal trauma is invaluable in order Computed tomography to: • diagnose the presence of a fracture The major advantages of multidetector computed tomog- • assess the type of fracture (Box 14. In the spine, fractures of the pedicles, abnormal bone (pathological fracture) laminae and articular facets as well as fragments displaced • assess soft tissue injury and locate any foreign bodies. In fractures of the pelvis, especially those around the views, preferably at right angles to one another. It is also very helpful in tibial plateau fractures and fractures of the ankle, calca- Box 14. The examination is • Burst/crush quick, an important factor in patients with serious internal • Insuffciency injuries. Magnetic resonance imaging is also very useful for dem- onstrating injury to soft tissues such as muscle, tendons and ligaments and is particularly useful in knee injuries (Fig. Radionuclide bone scanning Fractures may not be visible on plain flms, and, in these instances, radionuclide bone scanning maybe helpful (Fig. The bone scans show increased activity at Even though cortical bone does not produce a magnetic injured sites within 2–3 days. Increased activity persists for resonance signal, a fracture can be seen as a dark line across as long as the fractures are healing, often lasting several the bright signal of the fat in the marrow on a T1-weighted months. In- resembling metastases, but usually the distribution sug- creased signal intensity is seen within the bone, represent- gests injury. Skeletal Trauma 403 Imaging fractures Frequently, a fracture is very obvious but in some cases the changes are more subtle. Occasionally, the fracture appears as a dense line from the overlap of the fragments (Fig. Interruption of bony trabeculae is of use in impacted fractures where there is no visible lucent line. Bulging or buckling of the cortex is a particularly important sign in children, where fractures are frequently of the greenstick type (Fig. Soft tissue swelling may be a valuable guide to the presence of an underlying fracture. A joint effusion may become visible following trauma, and, as in elbow fractures, displaced fat pads may indicate an occult radial head fracture (Fig. With tibial fractures, for example, the fbula is frequently also broken but the fractures may be a consider- able distance apart. Imaging dislocations The joint surfaces no longer maintain their normal relation- ship to each other. Further plain flm views Injuries may sometimes be invisible even with two views taken at right angles to each other. If the radiographic fnd- ings are equivocal, or if there is clinical suspicion of bony injury with normal radiographs, then further flms should be taken as follows: (b) • Different projections, e. There is increased activity in the scaphoid in this patient who suffered continuing pain after trauma to the wrist. In spite of normal x-rays, the bone scan indicates there is a fracture that was not visible on the radiographs. There is increased uptake in the sacrum in this elderly woman who had a normal pelvic x-ray. Flexion and extension views • Interruption of bony trabeculae • Bulging or buckling of the cortex should not be carried out on the unconscious patient. Comparison with the normal side • Joint effusion can be useful in the problem case, particularly if expert help is not available. This applies largely in children where epiphyseal lines and unusual patterns of ossifcation may • Flexion and extension views. This is usually much more injury, resorption of the bone at the fracture site may then obvious on a flm taken with the neck fexed (Fig. Inversion stress on the ankle opens up the lateral joint indicating rupture of the lateral ligaments. Specifc injuries Numerous types of fractures and dislocations may be encountered and it is not practical to describe and illustrate them all in this book. The following section is an atlas illustrating a selection of the more common and important injuries. Salter–Harris classifcation (a) (b) Fractures of an epiphysis, growth plate or metaphysis of the long bones often occur in children and may lead to Fig. Five types are recognized in the Salter–Harris Films taken 2 weeks after the injury show a fracture through the classifcation (Fig. Note that in both examples the fracture runs through the metaphysis as well as through the epiphyseal (b) (c) plate (arrows). Upward displacement of the medial fragment is frequently seen, as in this example. The head of the humerus is displaced inferior and anterior to the glenoid fossa to Fig. Note the internal rotation of the humerus and lack of congruity of the humeral head with the glenoid. These fractures occur in children and are potentially dangerous because of possible injury to the brachial artery and nerve damage. Fractures of the epicondyles occur in children before the ulnar styloid is avulsed in addition, as in this example. They are serious injuries because if missed non-union or avascular necrosis may supervene. The fracture (arrow), as in this example, is usually across the waist of the scaphoid. Alternatively, and often diffcult to differentiate, is anterior dislocation of the lunate. This patient, who suffered an industrial accident, has a dislocation of the proximal interphalangeal joint of the ring fnger with a fracture through the base of the middle phalanx (upward arrow).
These signals function coordinately and target defined effectors for epicardial cells to lose their intercellular adhesions proven carbamazepine 400mg spasms lower right abdomen, acquire a mesenchymal invasive phenotype cheap 100 mg carbamazepine with visa spasms kidney stones, and migrate into the extracellular matrix and adjacent myocardium order carbamazepine 100 mg line spasms thumb joint. However, the origin of coronary vascular endothelium remains a subject of much debate (372). Thus, recent lineage tracing suggests that there is a significant population of coronary arterial endothelial cells that are derived from the endocardial cells migrating through the ventricular myocardial wall (373). The left- and right-sided and bottom panels show results of a quail–chicken chimera study, which assessed the fate of the quail proepicardial organ transplanted onto the venous pole of a chicken embryonic heart. During development, the quail donor epicardial cells first form a sheet of epicardial cells covering the myocardial wall (black dots), which then migrate into the compact layer of the myocardium to form the walls of the coronary arteries (ca) and the cardiac fibroblasts. Although green arrows are included to indicate positive regulation of the grouped genes of downstream processes, the putative pathways of positive and negative interactions between different genes, transcription factors, and signaling molecules are omitted, as the reported data are largely inconsistent. Note, that muscularization of the coronary arteries begins from the proximal coronary arterial trunks. Development of the cardiac coronary vascular endothelium, studied with anti-endothelial antibodies, in chicken- quail chimeras. Rebuilding the coronary vasculature: Hedgehog as a new candidate for pharmacologic revascularization. Thus, the coronary arteries are formed in situ as tiny discontinuous vascular channels, initially disconnected from the developing ascending aorta (343,374,375,376). Interestingly, as the branches of the coronary arteries develop independently from a connection with their central stems, their initial large size is set in the absence of blood flow. After their formation, the coronary arteries are extensively remodeled, and the degree of variation in the definitive arrangement of coronary arterial system suggests that there is much latitude in the production of the adult structure (343). The mechanisms that govern the patterning and regulation of coronary vessel size, as well as the determination of location of their formation, are largely unknown. The proximity of epicardial cells to the cardiac muscle can play a role in an activation of their vasculogenetic potential. A unique aspect of the development of the coronary arterial circulation is the final connection of the central coronary arteries to the aorta, which was extensively studied in quail and chicken embryos. The origins of the right and left main coronary arterial stems can be highly variable in some forms of congenital heart defects. Anomalous origin of the main coronary arteries either from an inappropriate sinus or from the pulmonary trunk can also occur as isolated malformations in otherwise normally formed heart. The central coronary arteries start their development as multiple subepicardial endothelial channels forming a ring of capillaries surrounding the entire circumference of the distal outflow tract (Fig. The capillaries of this peritruncal plexus are connected with the peripheral subepicardial coronary endothelial channels. Multiple capillaries originating from the peritruncal capillary ring then grow toward the aortic wall and penetrate it (Fig. However, only two vessels, each in the vicinity of the developing right and left facing sinuses of the aortic root, persist, by which the right and left main coronary arterial stems become established. Immunohistochemical studies in quail embryos have shown that these two main coronary arterial stems are formed through coalescence of the multiple peritruncal capillaries (Fig. Acquisition of the smooth muscular tunica media plays a stabilizing function in those P. The exclusive association of the cardiac neural crest–derived parasympathetic ganglia and nerves with persisting central coronary arteries was also shown to be essential to the survival of the definitive main coronary arterial stems (383). More recently it has been demonstrated that neural crest–derived cells from the preotic region, as opposed to the cardiac neural crest, migrate toward the heart and differentiate into coronary artery smooth muscle cells. Furthermore, proper coronary artery orifice development is associated with the production of the Fas ligand by epicardially derived cells as an apoptotic inductor at the sites of coronary ingrowth (385). A–D: Demonstrate the formation of the proximal trunks of the coronary arteries from the peritruncal capillary plexus and their ingrowth through the wall of the ascending aorta (Ao), as visualized by red fluorescence protein expression under control of the Apln- promotor, which was found to be active only in the endothelium of the peripheral coronary arteries. E–G: Provide a closer look at the process of penetration and fusion of the proximal coronary arterial capillaries through the aortic wall in quail embryos to form the orifices of the left and right main coronary arteries. H: Summarizes schematically the concept of fusion of the capillaries derived from the peritruncal ring to form two main coronary arteries connecting with their respective aortic sinuses, the process of which is probably regulated by the neural crest–derived ganglia (g). Peritruncal coronary endothelial cells contribute to proximal coronary artery stems and their aortic orifices in the mouse heart. Development of proximal coronary arteries in quail embryonic heart: multiple capillaries penetrating the aortic sinus fuse to form main coronary trunk. Expression of this gene allowed distinguishing the coronary endothelial cells of the developing heart from those of the aortic wall, and demonstrated the ingrowth of the main coronary arterial stems through the aortic wall (Fig. Interestingly, the cardiomyocytes within the developing aortic wall specifically persist at stem sites, where they surround maturing ostia of the main coronary arteries in both, mouse and human hearts (387). It seems that these persisting aortic wall cardiomyocytes are important in guiding the main coronary arteries toward proper aortic root sinuses. In hearts with outflow tract rotation defects, misplaced coronary arterial stems were associated with shifted aortic wall cardiomyocytes (388,389). However, despite all the progress made in establishing the developmental mechanisms underlying the correct formation of the two main coronary arteries originating from the aortic root, it is still largely unknown why only the aorta but not the pulmonary trunk receives penetrating peritruncal capillaries. It is also still enigmatic how the peritruncal coronary channels are guided to the aortic wall, and why only the right and left sinuses have coronary arterial ostia in the formed heart while initially all three aortic root sinuses receive penetrating capillaries. Development of the human heart from its first appearance to the stage found in embryos of twenty paired somites. The partitioning of the truncus and conus and the formation of the membranous portion of the interventricular septum in the human heart. Pathogenesis of transposition complexes: Embryology of the ventricles and great arteries. Transformation of the aortic-arch system during the development of the human embryo. A Compilation of Paintings on the Normal and Pathologic Anatomy and Physiology, Embryology, and Diseases of the Heart. Symptomatic heart disease in infants: comparison of three studies performed during 1969–1987. Sequential chamber localization: logical approach to diagnosis in congenital heart disease. Cardiac progenitor cells from adult myocardium: homing, differentiation, and fusion after infarction. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Direct reprogramming of fibroblasts into functional cardiomyocytes by defined factors. The House Mouse: Development and Normal Stages from Fertilization to 4 Weeks of Age. Can recent insights into cardiac development improve our understanding of congenitally malformed hearts?
An example of these movements occurs in an individual in a Due to the tonic infuence of each moving vehicle watching an object in the pass- frontal eye feld on the contralat- ing landscape discount 400mg carbamazepine visa muscle relaxant clonazepam. The eyes will automatically fol- eral horizontal gaze center order carbamazepine amex spasms post stroke, acute lesions of the low the particular object in the landscape until frontal eye feld result in conjugate deviation it disappears from view cheap 100 mg carbamazepine otc spasms sentence, at which time the eyes of the eyes toward the side of the lesion and move rapidly in the opposite direction and fx paralysis of voluntary gaze toward the contra- on a new object in the landscape. An irritative lesion such phenomenon occurs when vision is directed as occurs in a focal seizure results in devia- at alternating vertical black and white stripes tion of the eyes to the contralateral side. The eyes will fx on abnormalities are transient because of the a particular black stripe, follow it until it dis- bilateralism of these cortical connections with appears from view, and then move rapidly in the brainstem gaze centers. These slow drifting and fast return movements are referred to as optoki- Parietal and Temporal Eye Fields netic nystagmus. The superior parietal lobule affects Clinical saccadic movements through reciprocal connec- Connection tions with the frontal eye feld and projections to the superior colliculus. An absence or decrease in opto- kinetic nystagmus results from lesions of subcortical or cortical structures involved in the visual motion pathway, which Clinical includes the visual cortex and posterior tem- Connection poral areas. The absence or decrease is mani- fested only when an object is rotating toward The superior parietal lobule plays the side of the lesion. Patients with lesions in this area neglect objects on the opposite side and have diffculty in mak- Occipital Eye Field ing eye movements toward that side. The primary visual and visual association areas in the occipital cortex form the occipital eye An area in the posterior part of the lateral feld, which controls vergence movements. This phenomenon is suit movements, although the superior parietal called the near response and includes simulta- lobule and frontal eye feld may also be involved. Thus, focal lesions in the brainstem gray and white layers that are subdivided into interrupt only a small portion of the total input superfcial, intermediate, and deep layers. The fron- tal eye feld projects to the intermediate layers Clinical and sensory paths ascending through the brain- Connection stem, especially the pain and auditory paths, proj- ect to the deep layers. Output from the superior Programming of eye movements colliculus ascends to visual association areas via appears to occur not only in the pulvinar and descends into the brainstem and the cerebral cortex and brainstem but also spinal cord. Input reaches the head turning of the head and eyes in response to star- of the caudate nucleus via corticostriate projec- tling pain or auditory stimuli. Outputs trol of ordinary eye movements is not entirely chiefy from the substantia nigra (reticular part) clear. Because of the input it receives from the pass to the ventral anterior nuclei and medial retina and cortical eye felds and its output to the dorsal thalamic nuclei, which, in turn, directly brainstem gaze centers, this structure undoubt- infuence the frontal eye feld and adjacent edly plays a role as a visuomotor integration parts of the prefrontal cortex. In basal ganglia center especially concerned with refex ocular disorders such as Parkinson disease, normal movements. Lesions of the superior colliculi do spontaneous ocular movements are lacking not result in major eye movement abnormalities or seldom occur. This phenomenon, along due to the diversity of the connections between with slightly widened palpebral fssures and the cortical and brainstem gaze centers. For infrequent blinking, gives the eyes a staring instance, the frontal eye felds project bilaterally appearance. Vestibulo-ocular connections then carry the reticular formation adjacent to the the cerebellar infuences to the nuclei of the ocu- abducens nucleus results in paralysis of lar motor nerves. Which result in a conspicuous nystagmus, especially of the following structures has been when the eyes are directed toward the side of the affected? A small contusion injury to the cerebral sclerosis awakens with double vision, cortex on the left side damages the frontal seeing two side-by-side images whenever eye feld. A patient presents with esotropia and detected by neuroimaging in an 80-year- horizontal diplopia. If this tumor increases in characteristic of: size, the frst defcit you would expect to a. The frst patient has loss of general sensations below the umbilicus, such that on the right side only the touch, pressure, and proprioceptive senses are lost whereas on the left side only the pain and temperature senses are lost. The second patient has loss of pinprick and temperature sensations on the left side in the limbs, trunk, neck, and back of the head and on the right side on the face and anterior part of the scalp. The third patient has total left hemianesthesia, that is, loss of pinprick, tem- perature, touch, pressure, and proprioceptive senses on the left side of the entire body. All sensations arising from the skin, connective Light Touch tissues, voluntary muscles, periosteum, teeth, etc. Light touch includes three other phenomena: The general senses include light touch or tactile two-point sense, stereognosis, and graphes- discrimination and sensations of pressure or deep thesia. Two-point sense is the ability to distin- touch, vibration, proprioception, pain, and tem- guish stimulation by one or two points applied perature. The minimal distance between three neurons: number 1 in the sensory ganglia, the two points that can be felt separately var- number 2 in the spinal cord or brainstem or both, ies considerably on different parts of the body. Two points can be distinguished as close as 1 mm 132 Chapter 11 The Somatosensory System: Anesthesia and Analgesia 133 on the tip of the tongue and 2 to 4 mm on the movement. Position sense can be tested by pas- fngertips, whereas on the dorsum of the hand sively moving a limb or one of its parts to a cer- two points closer than 20 to 30 mm cannot be tain position and having the subject move the distinguished from one another. A patient the ability to recognize objects by touch alone, who can stand with the feet together and the eyes using the object’s size, shape, texture, weight, open, but who sways and falls when the eyes are etc. Graphesthesia is the ability to recognize closed, has the Romberg sign, which indicates an numbers or letters drawn on the skin. Both ste- absence of position sense in the lower limbs (see reognosis and graphesthesia require intact light Chapter 13). Pain There are two types of pain or nociceptive (noci means noxious) sensations: fast and slow. Fast Pressure pain is of the sharp, pricking type and is well The perception of pressure involves stimuli localized. Pressure by alternately touching the tip and head of a sense is tested by frmly pressing on the skin with safety pin to the surface of the skin. The patient a blunt object and by squeezing the subcutaneous should be able to readily distinguish the sharp- structures and muscles. Pressure sensations are ness of the tip of the pin from the dullness of the often referred to as deep touch. Vibration Sense Itch was formerly associated with pain- When the shaft of an oscillating high-frequency conducting nerve fbers, but is now thought (256 vibrations per second) tuning fork is gently to occur via a separate group of very slow con- applied to the skin overlying the bony promi- ducting nonmyelinated fbers with histamine nences, vibrations in the subcutaneous tissues are receptors. Vibration sense, therefore, requires intact pathways from deep structures such as Temperature subcutaneous connective tissue, periosteum, and muscle. Temperature sensations range from cold to cool When an oscillating low-frequency (128 vibra- to warm to hot and are tested by touching the tions per second) tuning fork is used, the sensa- skin with test tubes flled with either cold or tion is described as “futter” or fne vibrations in warm water. With axon, which bifurcates into a peripheral branch eyes closed, the subject should be able to rec- and a central branch. Rapidly adapting mech- peripheral branch enters the spinal or cranial anoreceptors signal the onset and cessation of a nerve and eventually terminates as an ending stimulus and are important for sensing movement that responds to a specifc type of stimulus. Discrete tactile stimula- encapsulated sensory nerve endings transduce tion is detected by Merkel discs and Meissner the physical stimulus into electrical receptor corpuscles located in superfcial layers predomi- potentials that encode stimulus strength and nately in glabrous skin. The corpuscles are encapsulated by many fattened cutaneous area over which a receptor is acti- epithelial cells. The size of est receptive felds and most importantly signal receptive felds for the same receptor types var- discrete indentations of the skin. Merkel discs ies in different parts of the body, generally being also provide information about the curvature smallest at the tips of the fngers and perioral of objects.
Remodelling of the right ventricle after early pulmonary valve replacement in children with repaired tetralogy of Fallot: assessment by cardiovascular magnetic resonance carbamazepine 400 mg without prescription zma muscle relaxant. Pulmonary valve replacement in patients with tetralogy of Fallot and pulmonary regurgitation: early surgery similar to optimal timing of surgery? Magnetic resonance imaging to assess the hemodynamic effects of pulmonary valve replacement in adults late after repair of tetralogy of fallot carbamazepine 100mg amex muscle relaxant pediatrics. Optimal timing for pulmonary valve replacement in adults after tetralogy of Fallot repair discount 400mg carbamazepine overnight delivery yellow round muscle relaxant pill. Ventricular fibrosis suggested by cardiovascular magnetic resonance in adults with repaired tetralogy of fallot and its relationship to adverse markers of clinical outcome. Histopathology of the right ventricular outflow tract and its relationship to clinical outcomes and arrhythmias in patients with tetralogy of Fallot. Corrected tetralogy of Fallot: delayed enhancement in right ventricular outflow tract. Effects of regional dysfunction and late gadolinium enhancement on global right ventricular function and exercise capacity in patients with repaired tetralogy of Fallot. Diffuse myocardial fibrosis following tetralogy of Fallot repair: a T1 mapping cardiac magnetic resonance study. Mechanoelectrical interaction in tetralogy of fallot: qrs prolongation relates to right ventricular size and predicts malignant ventricular arrhythmias and sudden death. Characterization of right ventricular diastolic performance after complete repair of tetralogy of Fallot. Acute right ventricular restrictive physiology after repair of tetralogy of Fallot: association with myocardial injury and oxidative stress. Impact of restrictive physiology on intrinsic diastolic right ventricular function and lusitropy in children and adolescents after repair of tetralogy of Fallot. Does restrictive right ventricular physiology in the early postoperative period predict subsequent right ventricular restriction after repair of tetralogy of Fallot? Right ventricular diastolic function in children with pulmonary regurgitation after repair of tetralogy of Fallot: volumetric evaluation by magnetic resonance velocity mapping. Relationship between type of outflow tract repair and postoperative right ventricular diastolic physiology in tetralogy of fallot: implications for long-term outcome. The impact of pulmonary valve replacement after tetralogy of Fallot repair: a matched comparison. Pulmonary valve replacement in tetralogy of fallot: impact on survival and ventricular tachycardia. Preoperative thresholds for pulmonary valve replacement in patients with corrected tetralogy of Fallot using cardiovascular magnetic resonance. Pulmonary valve replacement in adults late after repair of tetralogy of fallot: Are we operating too late? Outcomes after late reoperation in patients with repaired tetralogy of Fallot: the impact of arrhythmia and arrhythmia surgery. Impact of pulmonary valve replacement on arrhythmia propensity late after repair of tetralogy of Fallot. Left heart function in children with tetralogy of Fallot before and after palliative or corrective surgery. Total correction of tetralogy of Fallot in infancy, Postoperative hemodynamic evaluation. Left ventricular function after repair of tetralogy of fallot and its relationship to age at surgery. Left ventricular contractile state after surgical correction of tetralogy of Fallot: risk factors for late left ventricular dysfunction. Left ventricular dysfunction on exercise long term after total repair of tetralogy of fallot. Left ventricular dysfunction is a risk factor for sudden cardiac death in adults late after repair of tetralogy of Fallot. Factors associated with impaired clinical status in long-term survivors of tetralogy of Fallot repair evaluated by magnetic resonance imaging. Anatomy and myoarchitecture of the left ventricular wall in normal and in disease. Influence of right ventricular filling pressure on left ventricular pressure and dimension. Effects of diastolic transseptal pressure gradient on ventricular septal position and motion. Right ventricular function in adults with repaired tetralogy of Fallot assessed with cardiovascular magnetic resonance imaging: detrimental role of right ventricular outflow aneurysms or akinesia and adverse right-to-left ventricular interaction. The left heart after pulmonary valve replacement in adults late after tetralogy of Fallot repair. Structural abnormalities of great arterial walls in congenital heart disease: light and electron microscopic analyses. Aortic root dilation and aortic elastic properties in children after repair of tetralogy of Fallot. Prevalence and optimal management strategy for aortic regurgitation in tetralogy of Fallot. Aortic valve replacement after repair of pulmonary atresia and ventricular septal defect of tetralogy of Fallot. Massive aortic aneurysm and dissection in repaired tetralogy of Fallot; diagnosis by cardiovascular magnetic resonance imaging. Choosing the best contraceptive method for the adult with congenital heart disease. Dearani Persistent truncus arteriosus is an uncommon congenital cardiovascular malformation. There is no striking gender difference in frequency, although most series contained more male than female subjects. Truncus arteriosus usually occurs as an isolated cardiovascular malformation, although it has been reported in association with anomalies of other systems, particularly the DiGeorge or velocardiofacial syndrome (microdeletion chromosome 22q11. The anomaly has occurred in dizygotic twins (5) and siblings, and there is an increased incidence of cardiac malformations in relatives of children with this lesion (6,7,8). Because corrective operation for this malformation was first performed more than 30 years ago (9) ever-increasing numbers of postoperative patients are now reaching adolescence and adulthood. Patients who have had truncus arteriosus corrected need continued follow-up care throughout life. During the last 30 years, surgical correction of truncus arteriosus during infancy has become routine (10,11). Embryology The embryonic truncus arteriosus lies between the conus cordis proximally and the aortic sac and aortic arch system distally.