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Results for “Anatomic Landmarks”

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At least 217 records · Page 12Linked to original sources

PubMed2007

Ventricular epicardial lead placement for resynchronization by determination of paced depolarization intervals: technique and rationale.

BACKGROUND: Cardiac resynchronization therapy has been shown to be an effective treatment to improve functional status and prolong survival among patients with advanced congestive heart failure. However, as many as 30% of patients do not respond. Nonresponse may be due to suboptimal left ventricular lead placement. Studies have indicated that leads placed in the midlateral left ventricle (LV) wall usually result in improved dP/dT and increased pulse pressure, compared with other locations. When the surgeon is placing the leads thoracoscopically, however, in a chest with multiple adhesions, anatomic landmarks can be obscured. It is desirable to have an objective physiologic method to determine optimal lead placement. The optimal LV pacing site may be best determined by locating the site with the latest depolarization. METHODS: A pacing lead attached to a pulse analyzer was introduced through a thoracoscopic port and used as a mapping electrode to electrically map exposed areas of the left ventricle. The right ventricular pacing lead was also attached to the pulse analyzer and the interval between the right ventricular pulse and the LV depolarization (paced depolarization interval) was measured in 19 patients undergoing thoracoscopic LV lead placement. A site with a paced depolarization interval less than 110 ms was not accepted. RESULTS: Electrical mapping was possible in 19 of 29 consecutive patients in whom it was attempted. The most frequent reason for not mapping was the presence of extensive scarring. In 7 of 19 patients (36.8%) mapped, the site that would have been chosen by anatomic landmarks was not the site with the longest paced depolarization interval, and thus the lead placement was altered. CONCLUSIONS: The site with the longest paced depolarization interval is only selected 63.2% of the time when utilizing anatomic landmarks for placement. Nonresponse may be due to suboptimal LV lead placement. Measurement of paced depolarization intervals provides a physiologic method of determining optimal LV lead placement.

Cardiac Pacing, Artificial↗

PubMed2003

Ultrasound guidance speeds execution and improves the quality of supraclavicular block.

UNLABELLED: In this prospective study, we assessed the quality, safety, and execution time of supraclavicular block of the brachial plexus using ultrasonic guidance and neurostimulation compared with a supraclavicular technique that used anatomical landmarks and neurostimulation. It was hypothesized that ultrasonic guidance would increase the proportion of successful blocks, decrease block execution time, and reduce the incidence of complications such as pneumothorax and neuropathy. Eighty patients were randomized into two groups of 40, Group US (supraclavicular block guided in real time by a two-dimensional ultrasonic image, with neurostimulator confirmation of correct needle position) and Group NS (supraclavicular block using the subclavian perivascular approach, also with neurostimulator confirmation). Blocks were performed using bupivacaine 0.5% and lidocaine 2% (1:1 vol) with epinephrine 1:200000 as the anesthetic mixture. The onset of motor and sensory block for the musculocutaneous, median, radial, and ulnar nerves was evaluated over a 30 min period. At 30 min 95% of patients in Group US and 85% of patients in Group NS had a partial or complete sensory block of all nerve territories (P = 0.13) and 55% of patients in Group US and 65% of patients in Group NS had a complete block of all nerve territories (P = 0.25). Surgical anesthesia without supplementation was achieved in 85% of patients in Group US and 78% of patients in Group NS (P = 0.28). No patient in Group US and 8% of patients in Group NS required general anesthesia (P = 0.12). The quality of ulnar block was significantly inferior to the quality of block in other nerve territories in Group NS, but not in Group US; the quality of ulnar block was not significantly different between Groups NS and US. The block was performed in an average of 9.8 min in Group NS and 5.0 min in Group US (P = 0.0001). No major complication occurred in either group. We conclude that ultrasound-guided neurostimulator-confirmed supraclavicular block is more rapidly performed and provides a more complete block than supraclavicular block using anatomic landmarks and neurostimulator confirmation. IMPLICATIONS: Ultrasound-guided neurostimulator-confirmed supraclavicular block is more rapidly performed and provides a block of better quality than supraclavicular block using anatomic landmarks and neurostimulator confirmation.

Adult↗

PubMed2007

Reconstructing proximal humeral fractures using the bicipital groove as a landmark.

Controversy persists in the literature regarding the use of the bicipital groove as an anatomic landmark to restore humeral head retroversion when treating complex proximal humeral fractures with arthroplasty. We quantified the three-dimensional geometry of the bicipital groove in 49 dried humeri relative to the intramedullary axis, quantified the reliability of using the bicipital groove as an anatomic landmark, and compared this reliability with that of the conventional technique that uses a fixed, average angle relative to the epicondylar axis to establish humeral head retroversion. The data show the anterior offset of the bicipital groove is nearly constant from proximal (7.3 mm +/- 2.8 mm) to distal (7.2 mm +/- 1.5 mm) relative to the intramedullary axis. Given the consistency, the distal bicipital groove (at the level of the surgical neck) is a reasonable landmark to establish humeral head retroversion after complex proximal humeral fractures having reliability (angular error of 7.9 degrees +/- 5.8 degrees) as good as or better than the conventional fixed-angle technique.

Humans↗

PubMed1999

Microsurgical anatomy of the temporal lobe: part 1: mesial temporal lobe anatomy and its vascular relationships as applied to amygdalohippocampectomy.

OBJECTIVE: We review the anatomy of the mesial temporal lobe region, establishing the relationships among the intraventricular, extraventricular, and surrounding vascular structures and their angiographic characterization. We also demonstrate the clinical application of these anatomic landmarks in an anatomic temporal lobectomy plus amygdalohippocampectomy. METHODS: Fifty-two adult cadaveric hemispheres and 12 adult cadaveric heads were studied, using a magnification ranging from 3x to 40x, after perfusion of the arteries and veins with colored latex. RESULTS: The intraventricular elements are the hippocampus, fimbria, amygdala, and choroidal fissure; the extraventricular elements are the uncus and parahippocampal and dentate gyri. The uncus has an anterior segment, an apex, and a posterior segment that has an inferior and a posteromedial surface; the uncus is related medially to cisternal elements and laterally to intraventricular elements. The anterior segment is related to the proximal sylvian fissure, internal carotid artery, proximal M1 segment of the middle cerebral artery, proximal cisternal anterior choroidal artery, and amygdala. The apex is related to the oculomotor nerve, uncal recess, and amygdala; the posteromedial surface is related to the P2A segment of the posterior cerebral artery inferiorly, to the distal cisternal anterior choroidal artery superiorly, and to the head of the hippocampus and amygdala intraventricularly. The choroidal fissure is located between the thalamus and fimbria; it begins at the inferior choroidal point behind the head of the hippocampus and constitutes the medial wall of the posterior two-thirds of the temporal horn. CONCLUSION: Not only is the knowledge of these relations useful to angiographically characterize the mesial temporal region, but it has also proven to be of extreme value during microsurgeries involving this region.

Adult↗

PubMed2003

Automatic construction of 3-D statistical deformation models of the brain using nonrigid registration.

In this paper, we show how the concept of statistical deformation models (SDMs) can be used for the construction of average models of the anatomy and their variability. SDMs are built by performing a statistical analysis of the deformations required to map anatomical features in one subject into the corresponding features in another subject. The concept of SDMs is similar to statistical shape models (SSMs) which capture statistical information about shapes across a population, but offers several advantages over SSMs. First, SDMs can be constructed directly from images such as three-dimensional (3-D) magnetic resonance (MR) or computer tomography volumes without the need for segmentation which is usually a prerequisite for the construction of SSMs. Instead, a nonrigid registration algorithm based on free-form deformations and normalized mutual information is used to compute the deformations required to establish dense correspondences between the reference subject and the subjects in the population class under investigation. Second, SDMs allow the construction of an atlas of the average anatomy as well as its variability across a population of subjects. Finally, SDMs take the 3-D nature of the underlying anatomy into account by analysing dense 3-D deformation fields rather than only information about the surface shape of anatomical structures. We show results for the construction of anatomical models of the brain from the MR images of 25 different subjects. The correspondences obtained by the nonrigid registration are evaluated using anatomical landmark locations and show an average error of 1.40 mm at these anatomical landmark positions. We also demonstrate that SDMs can be constructed so as to minimize the bias toward the chosen reference subject.

Algorithms↗

PubMed1999

Blind axillar venous access.

The axillary vein has been suggested as an alternate site for venous access to avoid the "subclavian crush phenomenon. " Many techniques have been used to access this structure. They include complicated anatomical landmarks, contrast venography, Doppler, and ultrasound. A simple technique using the basic anatomical landmark of the deltopectoral groove and a blind venous stick has been used successfully in 165 of 168 consecutive pacemaker and ICD procedures; there were only three failures. These required an alternate approach. With a thorough knowledge of the regional anatomy, the axillary vein can be safely used as a primary site of venous access.

Axillary Vein↗

PubMed1995

[Practical experience of specific catheter ablation of atrial flutter in 110 patients].

The object of this study was to assess the efficacy and risks of radiofrequency ablation of common atrial flutter and to determine the optimal site of ablation in a large population of patients. Three different methods were used to determine the site of ablation: the first was anatomical and electrophysiological whilst the two others were based essentially on anatomical landmarks for localising the critical zone of the reentry circuit. Recent studies report that radiofrequency ablation is effective in interrupting and preventing recurrences of common atrial flutter both by using anatomical and electrophysiological methods. Nevertheless, a larger series of patients was necessary to establish the efficacy and to determine the optimal site of ablation. A series of 110 consecutive patients with common atrial flutter resistant to antiarrhythmic drugs was studied. The site of ablation of the first 50 patients was determined using both anatomical landmarks and electrophysiological parameters. The anatomical zones were: zone 1, between the septal leaflet of the tricuspid valve and the orifice of the inferior vena cava; zone 2, between the septal leaflet of the tricuspid valve and the ostium of the coronary sinus, and zone 3: between the orifice of the inferior vena cava and the ostium of the coronary sinus. The electrophysiological criterion was an endocavitary auriculogramme occurring during the plateau phase preceding the F wave of the flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Endoscopic anatomy of the third ventricle.

42 cadaver brains in situ were examined endoscopically to work out topographical anatomical landmarks for orientation. The endoscopic route from the chosen precoronal trepanation point to the defined ventricular landmarks has been measured in 22 cases. The identification and measurements of the anatomical landmarks are helpful for safe and atraumatic endoscopical navigation within the ventricular system. Furthermore this article describes and discusses cerebral lesions during ventriculoscopy.

Brain Mapping↗

PubMed2002

Standardisation of the description of patellofemoral motion and comparison between different techniques.

Patellofemoral motion is significant clinically, yet in the literature many different methods and terminologies are used, thus making comparison between studies difficult. We review and explain the different methods used for the description of patellofemoral joint motion, compare these methods by experimentation, and propose a standardised method. We found three main methods for describing patellar motion: motion of the patella about femoral body fixed axes, about patellar body fixed axes, and a combination of these. Description about femoral body fixed axes does not make sense clinically. Description about patellar body fixed axes is straightforward, yet the definition of these axes is prone to error due to the lack of anatomical landmarks. The combination method makes most sense clinically and uses more easily found anatomical landmarks. Patellar flexion varied by up to 26% when describing the motion about different axes. Tilt and shift were highly sensitive to the choices of coordinate systems and the axes of motion. The pattern of rotation was consistent between all methods; however, differences between the methods increased with patellar flexion. We propose the description of patello-femoral motion in terms of shift (along a femoral medial-lateral axis), tilt (about the patellar long axis), rotation (about a floating patellar anterior-posterior axis) and flexion (about the femoral medial-lateral axis).

Femur↗

PubMed2004

Intelligent training system integrated in an echocardiography simulator.

Computer simulators play an important role in medical education. We have extended our simulator EchoComJ with an intelligent training system (ITS) to support trainees adjusting echocardiographic standard views. EchoComJ is an augmented reality application that combines real three-dimensional ultrasound data with a virtual heart model enabling one to simulate an echocardiographic examination. The ITS analyzes the image planes according to their position, orientation and the visualization of anatomical landmarks using fuzzy rules. An adaptive feedback is provided that colors the specific anatomic landmarks within the contours of the virtual model based on the quality of the image plane.

Artificial Intelligence↗

PubMed1998

New cephalometric images with a workstation. A preliminary report.

OBJECTIVE: This study was designed to test the feasibility of several types of enhancements for cephalometric computed radiographs through use of the Fuji Computed Radiography system (Fuji Photo Film Corp., Tokyo, Japan). STUDY DESIGN: The material consisted of four lateral cephalograms made with the Fuji Computed Radiography system that were enhanced by varying the gradient levels before processing by means of both A-type (straight gradation) curves and workstation-type (peaked) curves. The four workstation-type images were set with optical densities at the peak of the curve at 1.5, 1.7, 1.9, and 2.1. Ten observers evaluated eight anatomic landmarks comparing pairs of workstation-type images. The best workstation-type image was then compared with the A-type image for the same landmarks. RESULTS: For the four workstation-type images the best visualization of the anatomic landmarks was seen with workstation-type image 3, which had a maximum optical density of 1.9. Image 3 was also superior to the results of A-type image processing for most of the landmarks. CONCLUSION: Image enhancement with the application of a computed radiography system is effective for study of lateral cephalograms.

Cephalometry↗

PubMedDate not supplied

Validation of a technique for accurate fine-wire electrode placement into posterior gluteus medius using real-time ultrasound guidance.

Fine-wire electromyography is primarily utilised for the recording of activity of the deep musculature, however, due to the location of these muscles, accurate electrode placement is difficult. Real-time ultrasound imaging (RTUI) of muscle tissue has been used for the guidance of the needle insertion for the placement of electrodes into the muscles of the abdominal wall. The validity of RTUI guidance of needle insertion into the deep muscles has not been determined. A cadaveric study was conducted to evaluate the accuracy with which RTUI can be used to guide fine-wire electrode placement using the posterior fibres of gluteus medius (PGM) as an example. Pilot studies revealed that the ultrasound resolution of cadaveric tissue is markedly reduced making it impossible to directly evaluate the technique, therefore, three studies were conducted. An initial study involved the demarcation of the anatomical boundaries of PGM using RTUI to define a technique based on an anatomical landmark that was consisent with the in vivo RTUI guided needle placement technique. This anatomical landmark was then used as the guide for the cadaveric needle insertion. Once the needle was positioned 0.05 ml of dye was introduced and the specimen dissected. The dye was accurately placed in PGM in 100% of the specimens. Finally, fine-wire electrodes were inserted into the PGM of five volunteers and manoeuvres performed indicating the accuracy of placement. This study supports the use of ultrasound imaging for the accurate guidance of needle insertion for fine-wire and needle EMG electrodes.

Buttocks↗

PubMed1993

Ultrasound imaging aids infraclavicular brachial plexus block.

Infraclavicular approach to the brachial plexus provides adequate anesthesia of the entire arm. Local anesthetics can be deposited over cords and branches of brachial plexus above the formation of musculocutaneous and axillary nerves. The approach can also easily block ulnar segment of medial cord and intercostobrachial nerve, which helps preventing tourniquet pain. However, distance to the plexus is deeper than the other approaches so that current blind method using anatomical landmarks requires anesthesiologists' delicate manipulation and experience. Through ultrasonography, the location of subclavian artery, as an anatomical landmark, can be easily identified. It is then very easy and safe to perform infraclavicular brachial plexus block. Our new method showed 89% (n = 9) successful rate. The time for the block was 4.2 +/- 1.5 min and there was an average of 3.2 +/- 0.6 needle penetrations. Thirty three percent (n = 3) had subclavian artery been punctured without formation of hematoma clinically. No patient had clinical postoperative pneumothorax.

Adult↗

PubMed1999

[Comparison of the reliability of two 3D acquisition systems used for the study of anthropometric and postural parameters].

The goal of this study is to compare the between trials and between session reliability of the postural geometry (PG) and anthropometrical evaluations, obtained by the FreePoint (FP) system and the Motion Analysis System (MA). The potential of automatization of the anthropometric evaluation is also evaluate through the comparison of height measurements obtained by the two 3D systems and traditional anthropometrical tools. The PG of 15 adult control subjects (x: 25 years, SD: 6) evaluated on two occasions (1 week interval) and a mannequin on one occasion were evaluated with both systems. Each evaluation involved the identification of 52 anatomical landmarks followed by the acquisition of 5 trials with each system. The 3 dimensional position of the anatomical landmarks serves to define a postural model including the shoulder girdle, spinous processes (T1 to S1), thorax, pelvis, lower extremities and base of support. Postural parameters were calculated, including rotations, tilts, versions, kyphosis, lordosis, right and left Cobb, anteroposterior shifts, (AP), mediolateral shifts (ML) and vertical heights. The between trials and between session results demonstrate a strong correspondence of the 15 anthropometric heights and the 20 postural parameters between the three systems, permitting the proposal of a broadened clinical utilisation of the FreePoint system. However, the validity of these measures is influenced by the reliability of the anthropometric landmarking, natural oscillation of the body and the intra-specific variation of the posture of each subject.

Adult↗

PubMed2006

Anterior retropharyngeal fixation C1-2 for stabilization of atlantoaxial instabilities: study of feasibility, technical description and preliminary results.

Posterior transarticular screw fixation C1-2 with the Magerl technique is a challenging procedure for stabilization of atlantoaxial instabilities. Although its high primary stability favoured it to sublaminar wire-based techniques, the close merging of the vertebral artery (VA) and its violation during screw passage inside the axis emphasizes its potential risk. Also, posterior approach to the upper cervical spine produces extensive, as well as traumatic soft-tissue stripping. In comparison, anterior transarticular screw fixation C1-2 is an atraumatic technique, but has been neglected in the literature, even though promising results are published and lectured to date. In 2004, anterior screw fixation C1-2 was introduced in our department for the treatment of atlantoaxial instabilities. As it showed convincing results, its general anatomic feasibility was worked up. The distance between mid-sagittal line of C2 and medial border of the VA groove resembles the most important anatomic landmark in anterior transarticular screw fixation C1-2. Therefore, CT based measurements on 42 healthy specimens without pathology of the cervical spine were performed. Our data are compiled in an extended collection of anatomic landmarks relevant for anterior transarticular screw fixation C1-2. Based on anatomic findings, the technique and its feasibility in daily clinical work is depicted and discussed on our preliminary results in seven patients.

Adolescent↗

PubMed2003

Variability in determination of point of needle insertion in peripheral nerve blocks: a comparison of experienced and inexperienced anaesthetists.

Accurate identification of surface landmarks is essential for the successful performance of peripheral nerve blocks. The variability between experienced and inexperienced practitioners in identifying anatomical landmarks has not been studied previously. Anaesthetists were asked to identify the point of needle insertion for posterior lumbar plexus and sciatic nerve blocks on a volunteer using a standard textbook description. The chosen point for needle insertion was described in terms of X and Y co-ordinates, measured in millimetres, from a zero reference point marked on a volunteer's back. Fifteen experienced and 22 inexperienced anaesthetists took part in the study. The lumbar plexus block mean [range] values for the X, Y co-ordinates were 80 [62-108], 66 [46-86] and 92 [49-150], 62 [0-131] in the experienced and inexperienced groups, respectively. The sciatic nerve block X, Y co-ordinates were 77 [62-99], 70 [49-89] and 68 [29-116], 62 [26-93] in the experienced and inexperienced groups, respectively. The variance for the point of needle insertion was significantly greater in the inexperienced group (p <0.01) for both the lumbar plexus and sciatic nerve blocks. We conclude that with increasing experience, there is decreased variability in determining the point of needle insertion using anatomical landmarks.

Anesthesiology↗

PubMedDate not supplied

Is routine ultrasound guidance for central line placement beneficial? A prospective analysis.

OBJECTIVE: Portable ultrasound devices have become more readily available in the intensive care unit setting, but their utility outside of controlled trials remains unproven. We sought to determine how the availability of ultrasound guidance affected the types and number of complications during central line placement. DESIGN: Review of a prospectively maintained database in a 20-bed combined intensive care unit. Procedure notes from all attempts at internal jugular vein access from 1996 to 2001 were recorded, and selected patient records were reviewed. Ultrasound guidance was available beginning in March 1998. RESULTS: From 1996 to 2001, there were 484 documented attempts at internal jugular central line placement. Most procedures (83%) were performed by first- or second-year residents. During this period, there were 47 complications for an overall complication rate of 10%. These included 1 pneumothorax (2%), 6 carotid punctures (13%), 2 hematomas (4%), and 34 unsuccessful attempts (72%). There was no significant difference in age, sex, body-mass index, or intubation status between those with and without complications or between the ultrasound and anatomic landmark groups. Ultrasound was used in 179 (37%) attempts. The overall complication rate with ultrasound was 11% versus 9% using anatomic landmarks (p = NS). The complication rate prior to the availability of ultrasound was 15 of 114 attempts (13%) versus 32 of 370 attempts (9%) after the introduction of ultrasound in our intensive care unit (p = NS). Analysis of the 370 procedures performed since ultrasound became available demonstrated a complication rate of 11% with ultrasound guidance versus 6% without (p = 0.09). There was no significant difference in complication rates by resident year group or department (surgery vs. other). However, procedures performed after-hours (1800 to 0800) were associated with a 15% complication rate versus 6% for procedures performed during the workday (p < 0.05). CONCLUSION: The availability and use of ultrasound guidance for central line placement by junior residents has not resulted in an improvement in procedure-related complications. The complication profile was not affected by ultrasound use, patient factors, or resident year in training. There was a higher complication rate associated with procedures performed at night that may be caused by resident fatigue or unavailability of senior supervision.

Adult↗

PubMed2006

Variability of landmark identification in total knee arthroplasty.

Virtual reality is new technology that is finding application in many facets of orthopaedics. We will describe an application of virtual reality in orthopaedic research. Component placement in total knee arthroplasty depends on identification of anatomic landmarks about the knee. We surmised significant interobserver variability occurs in the identification of landmarks of the distal femur used in total knee arthroplasty. The results tested in virtual space show that certain anatomic landmarks used in total knee arthroplasty are not reliable. The significance of this observation is that landmark identification, an integral component of computer-assisted surgical navigation in total knee arthroplasty, represents a source of method error in an otherwise accurate and precise computer-assisted technique.

Arthroplasty, Replacement, Knee↗