Cardiac tamponade.

Cardiac tamponade is a cardiological emergency requiring prompt treatment in order to avoid a fatal outcome. It can complicate a number of medical conditions and it is important, therefore, that all practitioners are aware of its presentation, diagnosis and management. These are outlined. We suggest that, with certain specific and important exceptions, percutaneous catheter pericardiocentesis is to be recommended in the management of cardiac tamponade. We include a review of 51 consecutive cases treated at our own institution. Catheter pericardiocentesis was successful in 49 (96%) cases and 36 (80%) patients did not require any further intervention. There were no major and only two minor complications which required no additional treatment. We review previous literature concerning percutaneous pericardiocentesis. Using recommended procedures, pericardiocentesis is successful in 90-100% of cases and major complications are rare.

Experience with cardiac tamponade following open heart surgery.

Cardiac tamponade following open heart surgery is well described, although, fortunately, uncommon. Unlike more classical "primary" tamponade, the clinical features are not specific, and this can delay diagnosis. In practice, the threshold for investigation must be low, and echocardiography has been invaluable in the detection and localization of pericardial collections. Several factors are believed to contribute to the likelihood of postoperative tamponade, but the mechanisms are not clearly understood. Resternotomy, under general anesthesia, or subxiphoid pericardiotomy, under local or general anesthesia, are effective forms of treatment. However, recent success with the use of percutaneous pericardiocentesis under echocardiographic guidance has shown that postoperative tamponade can be treated safely and effectively by this method.

Computer-aided mapping of the beta-adrenoceptor. 1. Explanation for effect of para substitution on blocking activity at the beta-1-adrenoceptor.

Anomalously low affinities for the beta-1-adrenoceptor are seen for members of a series of para-substituted N-isopropylphenoxypropanolamines in which the substituent is able to conjugate with the aromatic ring. The energy of conjugation was calculated using the AM1 semiempirical molecular orbital method and appears to correlate with the loss of binding energy, and hence affinity for the receptor. This suggests that binding is associated with movement of the substituent out of the plane of the aromatic ring due to steric interference with the receptor. A previously unrecognized binding site for aromatic groups off the para position is also identified.

Endoscopic bougie and balloon dilatation of multiple bronchial stenoses: 10 year follow up.

This paper reports 10 year follow up data on four patients who underwent mechanical dilatation of multiple bronchial stenoses (sarcoidosis two cases, berylliosis one case, idiopathic stenoses one case). Two patients enjoyed symptomatic and physiological improvement during the nine years before they presented with a recurrence of stenosis. The other two had recurrences sooner, and improved only slightly after they had started prednisolone treatment.

A one-variable topographical descriptor for the beta-turns of peptides and proteins.

The beta-turn is a common secondary structure in biologically active peptides and globular proteins, where it is widely thought to serve as a molecular recognition site for many biological processes. Although the primary beta-turn recognition requirements are thought to be straightforward, relating mainly to the relative positions of the peptide sidechains, current classifications of beta-turns are complex and are based solely upon the very variable geometry of the peptide backbone. We demonstrate here that beta-turns can be described in terms of a single dihedral angle, which we have called beta, which provides a complete description of the spatial relationship between the entry and exit peptide bonds as well as the relative orientations of the intervening sidechains for any beta-turn. This description should prove particularly useful in the development and application of novel peptide mimetic drugs, compounds for which a classification based on a peptide backbone geometry may be entirely irrelevant.

Conformational constraints: nonpeptide beta-turn mimics.

The beta-turn, which has also been referred to as the beta-bend, beta-loop or reverse turn, has been implicated as an important site for molecular recognition in many biologically active peptides and in globular proteins. This small secondary structure therefore makes an attractive target for mimicry by a conformational constraint, because a peptide which is constrained in a biologically active conformation can display a number of advantages over the parent substrate. The less peptide-like such a constraint is, the more potential there is to maximize these advantages. A decade has passed since the first (and highly successful) attempt to mimic the beta-turn with a nonpeptide conformational constraint was disclosed by Freidinger et al. (1980). Since this report, rapidly growing interest in the field of nonpeptide beta-turn mimics has seen a variety of experimental approaches and a mixed bag of results. It is attempted in this review, not only to summarize and critically analyse these approaches, but also to touch on the complexities associated with the conformational mimicry of such a diverse structure as the beta-turn.

The left paratracheal reflection.

The left paratracheal reflection, which is found medial to the left subclavian artery reflection, was sought in 302 normal posteroanterior (PA) chest radiographs, 93 conventional chest tomograms, and 113 thoracic computed tomographic (CT) scans. The left paratracheal reflection was visible on 31% of normal PA chest radiographs. Conventional tomography and CT showed that this finding is produced by contact of the lung with the mediastinum anterior to the left subclavian artery. The CT scans studied showed that the left paratracheal reflection actually represents contact of the lung with left paratracheal mediastinal fat 94% of the time, with the proximal 1-2 cm of the lateral wall of the left common carotid artery 5% of the time, and with the left tracheal wall 1% of the time. A variety of entities may alter the left paratracheal reflection.

Pneumolabyrinth as a late sequela of temporal bone fracture.

Pneumolabyrinth, air in the labyrinthine system, is an uncommon entity. We report one case, adding to previous reports of two such cases. The diagnosis was made radiologically, which has become possible only recently with the advent of high-resolution computed tomography (CT) scanners; we suspect it will be used more often in the future. To our knowledge, this is the first case in which pneumolabyrinth has been identified as a delayed sequela of a temporal bone fracture. Furthermore, this is the first description of a pneumolabyrinth occurring in a transverse temporal bone fracture.

Direct oblique sagittal CT of orbital wall fractures.

Direct oblique sagittal CT was used to evaluate trauma to 77 orbits. Sixty-seven orbital wall fractures with intact orbital rims (36 floor, 22 medial wall, nine roof) were identified in 47 orbits. Since persistent diplopia and/or enophthalmos may warrant surgical repair of orbital floor fractures, optimal imaging should include an evaluation of extraocular muscle status, the nature and amount of displaced orbital contents, and an accurate definition of fracture margins. For orbital floor fractures, a combination of the direct oblique sagittal and direct coronal projections optimally displayed all fracture margins, the fracture's relationship to the inferior orbital rim and medial orbital wall, and the amount of displacement into the maxillary sinus. Inferior rectus muscle status with 36 floor fractures was best seen on the direct oblique sagittal projection in 30 fractures (83.3%) and was equally well seen on sagittal and coronal projections in two fractures (5.5%). Floor fractures were missed on 100% of axial, 5.5% of sagittal, and 0% of coronal projections. Since the direct oblique sagittal projection complements the direct coronal projection in evaluating orbital floor fractures, it should not be performed alone. A technical approach to the CT evaluation or orbital wall fractures is presented.

Fundamentals of magnetic resonance imaging.

Recent advances in diagnostic imaging have accounted in part for the early detection of space occupying lesions in and around the temporal bone. To appreciate fully the modality of nuclear magnetic resonance imaging, the physician must understand the limitations and potential applications for this newest of radiologic studies. This update introduces the otologist to the language and principles of magnetic resonance imaging scanning.

Computed tomography of single-channel cochlear implants.

Computed tomographic (CT) examinations were performed in seven patients after cochlear implant surgery. Preimplantation CT demonstrated the petrous anatomy well and revealed an abnormality in one case. Postimplantation CT adequately assessed electrode position in all cases. Malposition of the active electrode was identified in one patient. Electrode position was correlated with postimplantation audiometric testing. A "transpetrous" projection was used to image perpendicular to the active electrode within the basal turn of the cochlea. A potential pitfall was identified where the ground electrode tip appeared to be embedded in the carotid canal cortex due to partial-volume averaging. With further experience, the clinical utility of CT in cochlear implantation patients will be better defined.

Complications of intravenous digital subtraction angiography.

Extracranial carotid occlusive disease can be evaluated with either intravenous (IV) digital subtraction angiography (DSA) or standard angiography. In a prospective study, complications related to 500 IV DSA examinations occurred in 16.6% of patients, including local complications in 2.0%, systemic complications in 15.0%, and neurologic complications in 3.0%. A permanent neurologic deficit occurred in one patient. Complications related to 150 standard angiograms occurred in 7.3% of patients, including local complications in 4.0%, systemic complications in 3.4%, and neurologic complications in 0.7%. There were no permanent neurologic deficits. Serious systemic and neurologic complications occurred in 8.2% of patients during IV DSA and 2.7% of patients during standard angiography. The rapid injection of high volumes of hypertonic contrast media during IV DSA and the resultant hemodynamic and cardiac electrophysiologic changes account for the higher incidence of complications with IV DSA.

Direct sagittal computed tomography of the head.

Direct sagittal computed tomography (CT) scanning of the cranium and face was facilitated using a fabricated to maintain the position of an adult patient's head on the scanner. A sponge was designed to fulfill the same purpose for children. Sagittal CT scanning of the head is easy to perform using these devices, and the additional equipment is inexpensive.

Bacteriologically confirmed pulmonary tuberculosis in childhood. Clinical and radiological features.

Over a 4-year period 185 cases of pulmonary tuberculosis in children were confirmed by culture of Mycobacterium tuberculosis, usually from gastric aspirate. The majority of cases occurred in boys (62%) and the younger age groups were more commonly affected--26% of patients were less than 1 year old and 65% less than 3 years of age. At the time of presentation 40% of the 151 children tested had a negative tuberculin test. A chest radiograph was available in 136 cases. The commonest changes seen were lymphadenopathy (63%) and segmental lesions (56%). The latter affected mainly the right lung and in particular the right middle lobe. Cavitating tuberculous disease was present in 19 children, including 5 aged less than 1 year.

Anterior sacral meningocele. Current diagnosis.

One hundred fifty cases of anterior sacral meningocele have been reported in the world literature. This rare pathologic entity was first recognized and described by Bryant in 1837. We report a patient with an incidental anterior sacral meningocele. Our patient is the oldest reported in the literature. The incidental feature of this malformation is uncommon. We review the literature and discuss the clinical aspect, diagnosis, and treatment. Emphasis is placed on the current and optimal method of radiologic evaluation using computed tomography scan combined with metrizamide myelography.

Direct sagittal computed tomography of the head in childhood.

Direct sagittal computed tomography (CT) was performed on 47 children with pathology in the posterior fossa, orbit, parasellar region, face and ear. The direct sagittal projection provided additional information about the extent of disease and relationship of the pathologic process to the adjacent tissues in 43% of patients studied. Direct sagittal CT has improved spatial resolution over reformatted images. It is readily available, less costly than magnetic resonance and can provide similar useful anatomic information.