Does total disc arthroplasty in C3/C4-segments change the kinematic features of axial rotation?

We analyze how kinematic properties of C3/C4-segments are modified after total disc arthroplasty (TDA) with PRESTIGE(®) and BRYAN(®) Cervical Discs. The measurements were focused on small ranges of axial rotation (<0.8°) in order to investigate physiologic rotations, which frequently occur in vivo. Eight human segments were stimulated by triangularly varying, axially directed torque. By using a 6D-measuring device with high resolution the response of segmental motion was characterised by the instantaneous helical axis (IHA). Position, direction, and migration rate of the IHA were measured before and after TDA. External parameters: constant axially directed pre-load, constant flexional/extensional and lateral-flexional pre-torque. The applied axial torque and IHA-direction did not run parallel. The IHA-direction was found to be rotated backwards and largely independent of the rotational angle, amount of axial pre-load, size of pre-torque, and TDA. In the intact segments pre-flexion/extension hardly influenced IHA-positions. After TDA, IHA-position was shifted backwards significantly (BRYAN-TDA: ≈8mm; PRESTIGE-TDA: ≈6mm) and in some segments laterally as well. Furthermore it was significantly shifted ventrally by pre-flexion and dorsally by pre-extension. The rate of lateral IHA-migration increased significantly after BRYAN-TDA during rightward or leftward rotations. In conclusion after the TDA the IHA-positions shifted backwards with significant increase in variability of the IHA-positions after the BRYAN-TDA more than in PRESTIGE-TDA. The TDA-procedure altered the segment kinematics considerably. TDA causes additional translations of the vertebrae, which superimpose the kinematics of the adjacent levels. The occurrence of adjacent level disease (ALD) is not excluded after the TDA for kinematical reasons.

Informatics in radiology: use of a C-arm fluoroscopy simulator to support training in intraoperative radiography.

Mobile image intensifier systems (C-arms) are used frequently in orthopedic and reconstructive surgery, especially in trauma and emergency settings, but image quality and radiation exposure levels may vary widely, depending on the extent of the C-arm operator's knowledge and experience. Current training programs consist mainly of theoretical instruction in C-arm operation, the physical foundations of radiography, and radiation avoidance, and are largely lacking in hands-on application. A computer-based simulation program such as that tested by the authors may be one way to improve the effectiveness of C-arm training. In computer simulations of various scenarios commonly encountered in the operating room, trainees using the virtX program interact with three-dimensional models to test their knowledge base and improve their skill levels. Radiographs showing the simulated patient anatomy and surgical implants are "reconstructed" from data computed on the basis of the trainee's positioning of models of a C-arm, patient, and table, and are displayed in real time on the desktop monitor. Trainee performance is signaled in real time by color graphics in several control panels and, on completion of the exercise, is compared in detail with the performance of an expert operator. Testing of this computer-based training program in continuing medical education courses for operating room personnel showed an improvement in the overall understanding of underlying principles of intraoperative radiography performed with a C-arm, with resultant higher image quality, lower overall radiation exposure, and greater time efficiency. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105125/-/DC1.

Visualization of transcoronary ablation of septal hypertrophy in patients with hypertrophic obstructive cardiomyopathy: a comparison between cardiac MRI, invasive measurements and echocardiography.

OBJECTIVE: Hypertrophic obstructive cardiomyopathy (HOCM) is treated by surgical myectomy or transcoronary ablation of septal hypertrophy (TASH). The aim of this study was to visualize the feasibility, success and short-term results of TASH on the basis of cardiac MRI (CMR) in comparison with cardiac catheterization and echocardiography. METHODS: In this in vivo study, nine patients with HOCM were treated with TASH. Patients were evaluated by transthoracic echocardiography, invasive cardiac angiography and CMR. Follow-up examinations were carried out after 1, 3 and 12 months. MR imaging was performed on a 1.5-T scanner. All images were processed using the semiautomatic Argus software and were evaluated by an attending thoracic radiologist and cardiologist. RESULTS: The echocardiographic pressure gradient (at rest) was 69.3 +/- 15.3 mmHg before and 22.1 +/- 5.7 mmHg after TASH (P < 0.01, n = 9). The flux acceleration over the aortic valve examined (V (max)) was 5.1 +/- 0.6 m/s before and 3.4 +/- 0.3 m/s after the TASH procedure (P < 0.05). Also, there was a decrease of septum thickness from 22.0 +/- 1.2 to 20.2 +/- 1.0 mm (P < 0.05) after 6 +/- 3 weeks. The invasively assessed pressure gradient at rest was reduced from 63.7 +/- 15.2 to 21.2 +/- 11.1 mmHg (P < 0.01) and the post-extrasystolic gradient was reduced from 138.9 +/- 12.7 to 45.6 +/- 16.5 mmHg (P < 0.01). All differences as well as the quantity of injected ethanol were plotted against the size or amount of scar tissue as assessed in the MRI. There was a statistically significant correlation between the post-extrasystolic gradient decrease and the amount of scar tissue (P = 0.03, r (2) = 0.5). In addition, the correlation between the quantity of ethanol and scar tissue area was highly significant (P < 0.01, r (2) = 0.6), whereas the values for the gradient deviation (P = 0.10, r (2) = 0.34), DeltaV (max) (P = 0.12, r (2) = 0.31), as well as the gradient at rest (P = 0.27, r (2) = 0.17) were not significant. CONCLUSION: TASH was consistently effective in reducing the gradient in all patients with HOCM. In contrast to the variables investigated by echocardiography, the invasively measured post-extrasystolic gradient correlated much better with the amount of scar tissue as assessed by CMR. We conclude that the optimal modality to visualize the TASH effect seems to be a combination of CMR and the invasive identification of the post-extrasystolic gradient.

Migration of the instantaneous axis of motion during axial rotation in lumbar segments and role of the zygapophysial joints.

The biomechanical role of the zygapophysial joints was investigated for axial rotations of lumbar segments by recording the positions of the instantaneous helical axis (IHA) against the axial rotational angle and by relating these IHA-positions to anatomical landmarks. Cyclically varying pure axial moments were applied to 3 L1/L2, 7 L3/L4 and 3 L4/L5 segments. There were 800 segment positions per cycle taken by a custom-made high precision 3D-position measuring system. In intact segments IHA-migration reached from one zygapophysial joint to the other IHA-paths came up to 10-60 mm within small angular intervals (±1 deg). After removing the right joints, IHA-migration remained comparable with that of intact segments only for segment positions rotated to the right. Rotation to the left, however, approximately yielded stationary IHA-positions as found after resection of both joints. Hence, IHA-migration is determined by the joints already for small rotational angles. Each type of segment showed a typical pattern of IHA-migration.

Acute aortic dissection type A discloses Corpus alienum.

We report an unusual case of an aortic type A dissection with a corpus alienum which compresses the right ventricle. The patient successfully underwent an aortic root replacement in deep hypothermia with re-implantation of the coronary arteries using a modified Bentall procedure and the resection of the corpus alienum. Intraoperative finding reveals 3 greatly adhered gauze compresses, which were most likely forgotten in the operation 34 years ago.

Non-linearity of flexion-extension characteristics in spinal segments.

Spinal biomechanics is still known just fragmentary since the only description by angle-torque characteristics without simultaneous recording of migration of the instantaneous helical axis (IHA) is not sufficient. Time-dependent flexion/extension following a cyclic laterally directed torque was measured at all six degrees of freedom by a highly precise custom-made 6D apparatus. In order to enhance the localizing resolution of IHA migration as the function of the flexional/extensional angle, small ranges of motion (ROM) were used at several degrees of pre-extension. 4 L3/L4, 3 L4/L5 and 2 T2/T3 human segments were investigated. In extensional motion, wide dorsal IHA-migrations were measured in lumbar segments and correlated with the distinct asymmetric shapes of the characteristics in extensional motion. The respective increase of differential stiffness could mainly be traced back to the enlarging geometrical moment of inertia of the segments by the dorsally migrating IHA. Both thoracic segments showed a predominant IHA-migration in cranial/caudal direction. A simple model makes it evident that the opposite curvature morphology of lumbar and thoracic joint facets conditions the different directions of IHA migration.

Beta-blockade does not alter plasma cytokine concentrations and ventricular function in young adults with right ventricular dysfunction secondary to operated congenital heart disease.

BACKGROUND: Right heart failure is a major problem of young adults with congenital heart disease (ACHD) that has been corrected by cardiac surgery. In left ventricular dysfunction (LVD), beta-blocker therapy improved cytokine concentrations and clinical status. Thus, the effect of bisoprolol on clinical status and plasma cytokine concentrations in ACHD patients with right heart failure after surgical correction for Tetralogy of Fallot was investigated. METHODS AND RESULTS: A prospective, randomized, double-blind, placebo controlled study for a duration of 6 months was carried out. A total of 34 patients (30.9+/-9.5 years; New York Heart Association I or II) with brain natriuretic peptide plasma concentrations >100 pg/ml and peak oxygen uptake <25 ml . kg(-1) .min(-1) were recruited. Bisoprolol did not reduce plasma concentrations of soluble tumor necrosis factor receptors (sTNF-R) and interleukin-6 (IL-6) in ACHD patients (before/after: sTNF-R1: 750+/-131/802+/-130; sTNF-R2: 3,693+/-1,043/4,166+/-840; IL-6: 12.94+/-26.03/13.69+/-16.58 pg/ml). Likewise, peak oxygen uptake, right and left ventricular parameters (determined by magnetic resonance imaging) were not improved by bisoprolol treatment. CONCLUSION: In contrast to previously observed beneficial effect(s) of beta-blockade in patients with LVD, there were no beneficial therapeutic effects or cytokine reduction in asymptomatic or minimal symptomatic ACHD patients. These data point to a different pathophysiological role of cytokines in ACHD patients with right ventricular dysfunction, as compared to patients with LVD.

A prospective, randomized, double-blind, placebo controlled trial of beta-blockade in patients who have undergone surgical correction of tetralogy of Fallot.

AIMS: Our purpose was to evaluate the effect of a treatment over six months with bisoprolol on the surrogate parameters of N-Terminal-pro brain natriuretic peptide, subsequently to be described as brain natriuretic peptide, peak uptake of oxygen, and ventricular function assessed by magnetic resonance imaging in grown ups and adults who had undergone surgical correction of tetralogy of Fallot. METHODS AND RESULTS: We designed a prospective, randomized, double-blind, placebo controlled trial. We enrolled 33 patients, aged 30.9 plus or minus 9.5 years in either class 1 or 2 of the grading of the New York Heart Association class with both levels of brain natriuretic peptide greater than 100 pg/ml and a reduced peak uptake of oxygen less than 25 ml/kg/min. During treatment with Bisoprolol, the levels of brain natriuretic peptide increased significantly from 206 plus or minus 95 to 341 plus or minus 250 pg/ml (p< 0.05), and those of atrial natriuretic peptide from 4117 plus or minus 1837 to 5340 plus or minus 2102 fmol/ml (p = 0.0005). These measures remained unchanged in the group of patients receiving the placebo. Peak uptake of oxygen did not differ significantly in either group, nor did treatment have any significant effect on right and left ventricular volumes and ejection fractions as determined by magnetic resonance imaging. The clinical state as judged within the grading system of the New York Heart Association was also unchanged by beta-blockade. CONCLUSION: Beta blockade with Bisoprolol seems to have no beneficial effect on asymptomatic or mildly symptomatic patients with right ventricular dysfunction secondary to repaired tetralogy of Fallot with residual pulmonary regurgitation and/or stenosis.

[Extramedullary hematopoiesis in the paravertebral space]. / Extramedulläre Blutbildung im paravertebralen Raum.

BACKGROUND: Extramedullary hematopoiesis is a response of the organism to a deficient production of blood-forming cells within the bone marrow. It may coincide with some hematologic diseases. Two patients with paravertebral mass lesions representing extramedullary hematopoiesis are discussed. Characteristic findings of extramedullary hematopoiesis are presented along with a review of the literature on this topic. CASE REPORTS: A 76-year-old male with a known myelodysplastic syndrome presented with pneumonia. In addition, he had symptoms of a cauda equina syndrome with complaints of pain and hypesthesia of the lower limbs as well as urinary retention. A 63-year-old female presented with aggravated complaints of the lower thorax, low back pain radiating to the upper left leg, and dysesthesia of both feet. In her past medical history, she had polycythemia vera and a splenectomy. Both patients showed paravertebral and intraspinal lesions located in the thoracic and sacral spine which were regarded as extramedullary hematopoiesis according to the imaging findings in MRI and CT. Radiation therapy showed marked improvement in their neurologic complaints following the initial sessions. CONCLUSION: Clinical presentation, knowledge of the underlying disease and of imaging findings are essential in the diagnosis of extramedullary hematopoiesis. MRI is the imaging modality of choice in the primary diagnosis of extramedullary hematopoiesis. Possible extension of the disease into the intraspinal space can be evaluated with high accuracy and differential diagnosis can be facilitated. In addition, MRI is of use in the accurate planning of radiation fields as well as during follow-up of extramedullary hematopoiesis.