Left axis deviation. Vectorcardiographic analysis of patients with left axis deviation.
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Diagnosis, Differential↗
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Studies on the normal polarcardiograms using the inferosuperior axis as the polar axis.
Polarcardiography made possible not only to let us know the polar coordinates of the cardiac vectors at any instant very easily, but also to express the time-related curve of the polar coordinates of the cardiac vectors, which vary as function of time, in easily understandable analogue pattern. Especially it was difficult to grasp the time-related curves of the polar coordinates of ST segment and T wave by means of the conventional electrocardiography and vector-cardiography. QRS waves, ST segments and T waves of the spatial magnitude ECG and I-S latitude ECG in normal subjects were classified into the several definite patterns.
Adult↗
[Hinge axis and kinematic axis].
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Dental Articulators↗
The effects of X-axis vertebral translation on projected Y-axis vertebral rotation.
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Chiropractic↗
Left ventricular volume measurement using cardiac axis nuclear magnetic resonance imaging. Validation by calibrated ventricular angiography.
Proton nuclear magnetic resonance (NMR) imaging has the potential to serially assess left ventricular (LV) volumes with optimal accuracy because it is a high-resolution, three-dimensional, noninvasive modality. Previous NMR studies to assess LV volumes have been suboptimal, as they have used either planes aligned with the axes of the body, which are compromised by partial volume effects, or spin-echo techniques that have been time-consuming to acquire and analyze. Accordingly, for LV volume measurement, we developed a gradient-echo (cine) NMR strategy that uses two orthogonal planes intersecting along the intrinsic long axis of the heart (two-chamber and four-chamber). This approach was validated against calibrated contrast biplane LV cineangiography (CATH) and also compared with a previously reported short-axis spin-echo NMR method. Twenty-one patients underwent CATH and NMR (long-axis, n = 21; short-axis, n = 14) within a 3-day interval. Although both long- and short-axis NMR LV volumes and ejection fractions correlated well with CATH (r greater than 0.90, p less than 0.001 in all), end-diastolic volumes by both long-axis (161 +/- 85 ml) and short-axis (151 +/- 81 ml) NMR were systematically less than those by CATH (182 +/- 85 ml) (p less than 0.05). Consequently, ejection fractions by long-axis (48 +/- 17%) and short-axis (49 +/- 17%) NMR consistently underestimated those by CATH (54 +/- 16%, p less than 0.05). End-systolic volumes by long-axis (94 +/- 71 ml) and short-axis (87 +/- 72 ml) NMR were not significantly different from those by CATH (92 +/- 69 ml). Both NMR techniques had low intraobserver and interobserver variation (less than 11%); however, short-axis spin-echo NMR involved longer acquisition/reconstruction (35 versus 18 minutes) and analysis (25 versus 10 minutes) times. We conclude that both short-axis spin-echo and long-axis gradient-echo NMR approaches reliably estimate LV volumes. Currently, the long-axis strategy appears more practical for clinical use because the scan and analysis times are relatively short.
Adult↗
Recognizing a plane-misoriented view of a familiar object is not influenced by the ease of specifying the main axis of elongation of that object.
Participants saw three versions of pictures of familiar objects: the original unaltered (axis-normal) pictures, axis-extended pictures in which the main axes of the axis-normal pictures were elongated, and axis-switched pictures in which objects that were originally horizontally elongated were depicted as vertically elongated and vice versa. Relative to axis-normal pictures, axis extension aided decisions about whether the picture of the object was wide or tall, and axis switching hindered these decisions for both upright and plane-misoriented views. Nevertheless, although these axis manipulations clearly influenced decisions about the location of the object's main axis of elongation, axis-switched pictures were no harder to name than axis-extended pictures. Changing the depicted main axis of elongation by axis switching and axis extension did not influence object recognition in itself, whether for upright or for plane-misoriented views. This suggests that specifying the main axis of elongation of an object does not play an important role in the orientation-sensitive processes involved in identifying plane-misoriented views of that object.
Form Perception↗
Auxin inducibility and developmental expression of axi 1: a gene directing auxin independent growth in tobacco protoplasts.
We describe the characterization of axi 1, a tobacco gene isolated by activation T-DNA tagging which apparently plays a role in auxin action. Upon deregulated expression, axi 1 confers on protoplasts the ability to grow in culture not only in the absence of auxin but also in high auxin concentrations where maximal frequencies of cell division are not observed in wild-type protoplasts. In wild-type plants axi 1 is transcribed principally in root tissue. In the tagged plant line, axi 159, axi 1 RNA can be detected in all tissues tested. Freshly isolated wild-type protoplasts require auxin for the accumulation of detectable levels of axi 1 transcript and this precedes maximal levels of cell division. In contrast, axi 1 RNA appears in protoplasts isolated from axi 159 plants in the absence of auxin. axi 1 was localized to 6.2 kb of plant genomic DNA flanking the right T-DNA border sequence. axi 1 is interrupted by nine introns and in tobacco it is a member of a small gene family. Database searching reveals no similarity within the coding region with other genes. Sequences within the fourth intron are similar to those located in the non-coding regions of other plant genes, some of which are known to be auxin inducible. A DNA fragment containing the conserved sequence acts as an auxin responsive element in transient expression assays in wild-type protoplasts and this response is higher in axi 159 protoplasts. This suggests that auxin induced axi 1 expression may be mediated by a region contained within an intron sequence and that the axi 1 product might play a role in this induction.
Base Sequence↗
The Collaborative Longitudinal Personality Disorders Study: reliability of axis I and II diagnoses.
Both the interrater and test-retest-retest reliability of axis I and axis II disorders were assessed using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) and the Diagnostic Interview for DSM-IV Personality Disorders (DIPD-IV). Fair-good median interrater kappa (.40-.75) were found for all axis II disorders diagnosed five times or more, except antisocial personality disorder (1.0). All of the test-retest kappa for axis II disorders, except for narcissistic personality disorder (1.0) and paranoid personality disorder (.39), were also found to be fair-good. Interrater and test-retest dimensional reliability figures for axis II were generally higher than those for their categorical counterparts; most were in the excellent range (> .75). In terms of axis I, excellent median interrater kappa were found for six of the 10 disorders diagnosed five times or more, whereas fair-good median interrater kappa were found for the other four axis I disorders. In general, test-retest reliability figures for axis I disorders were somewhat lower than the interrater reliability figures. Three test-retest kappa were in the excellent range, six were in the fair-good range, and one (for dysthymia) was in the poor range (.35). Taken together, the results of this study suggest that both axis I and axis II disorders can be diagnosed reliably when using appropriate semistructured interviews. They also suggest that the reliability of axis II disorders is roughly equivalent to that reliability found for most axis I disorders.
Diagnosis, Differential↗
The usefulness of exercise-induced QRS axis shift as a predictor of coronary artery disease.
The QRS axis of 101 patients with coronary artery disease (CAD) and 57 normal subjects without CAD who underwent coronary arteriograms were measured before and after exercise testing. There was no improvement in the sensitivity of positive axis shifts (15 degrees or greater) for CAD (18%) when compared to the value of positive ST depression (61%). However, the specificity of positive axis shifts for CAD was significantly increased (98%) when compared to the value of positive ST depression (77%). In addition, 39% of those patients with CAD (39 of 101) showed false negative ST depression, but 18% of these patients (7 of 39) showed a positive axis shift. In normal subjects 21% (12 of 57) showed false positive ST depression, but all of the 21% (12 of 12) showed negative axis shift. There was no significant difference in the increments of heart rate between positive ST depression, positive axis shift, and negative ST depression, negative axis shift. No statistical differences in the sensitivity of ST depression and an axis shift for one-, two- and three-vessel diseases were noted. The specificity of left-axis shift for the left anterior descending artery lesion was 98% and the specificity of right-axis shift for the right coronary artery and/or left circumflex artery lesion was 91%. Therefore, the axis shift response is no more sensitive for the detection of CAD than ST depression. However, when a positive axis shift is observed, one can predict two things: the CAD and the localization of the coronary stenosis.
Arrhythmias, Cardiac↗
Significance of left axis deviation in patients with chronic left bundle branch block.
Forty-nine patients with chronic left bundle branch block and a normal frontal axis were compared with 53 patients with left bundle branch block and left axis deviation. The following clinical variables were more frequent (P less than 0.05) in patients with left axis deviation: greater age, exertional angina, congestive heart failure, cardiomegaly, cardiac functional class II to IV, coronary artery disease and presence of organic heart disease. Absence of organic heart disease (primary conduction disease) was seen only in patients with a normal axis. Patients with left axis deviation had longer (P less than 0.05) mean P-R, A-H and H-V intervals and atrial and atrioventricular (A-V) nodal effective refractory periods. All patients were prospectifely followed up for 30 to 2,271 days with a mean +/- standard error of the mean follo-up period of 538 +/- 72 for the group with a normal axis and 604 +/- 72 days for the group with left axis deviation (difference not significant). A-V block developed in three patients (6 percent) with left axis deviation and in none of those with a normal axis. The cumulative 4 year mortality rate for the entire group approached 75 percent. The patients with left axis deviation had greater cardiovascular mortality (P less than 0.05). In conclusion, among patients with left bundle branch block, those with left axis deviation have a greater incidence of myocardial dysfunction, more advanced conduction desease and greater cardiovascular mortality than those with a normal axis.
Bundle-Branch Block↗
The anterior-posterior axis emerges respecting the morphology of the mouse embryo that changes and aligns with the uterus before gastrulation.
BACKGROUND: When the anterior-posterior axis of the mouse embryo becomes explicit at gastrulation, it is almost perpendicular to the long uterine axis. This led to the belief that the uterus could play a key role in positioning this future body axis. RESULTS: Here, we demonstrate that when the anterior-posterior axis first emerges it does not respect the axes of the uterus but, rather, the morphology of the embryo. Unexpectedly, the emerging anterior-posterior axis is initially aligned not with the long, but the short axis of the embryo. Then whether the embryo develops in vitro or in utero, the anterior-posterior axis becomes aligned with the long axis of embryo just prior to gastrulation. Of three mechanisms that could account for this apparent shift in anterior-posterior axis orientation-cell migration, spatial change of gene expression, or change in embryo shape-lineage tracing studies favor a shape change accompanied by restriction of the expression domain of anterior markers. This property of the embryo must be modulated by interactions with the uterus as ultimately the anterior-posterior and long axes of the embryo align with the left-right uterine axis. CONCLUSIONS: The emerging anterior-posterior axis relates to embryo morphology rather than that of the uterus. The apparent shift in its orientation to align with the long embryonic axis and with the uterus is associated with a change in embryo shape and a refinement of anterior gene expression pattern. This suggests an interdependence between anterior-posterior gene expression, the shape of the embryo, and the uterus.
Animals↗
Accuracy of a predetermined transverse horizontal mandibular axis point.
STATEMENT OF PROBLEM: The transverse horizontal mandibular axis point may be located most precisely by a kinematic process. However, an anatomical method of locating the axis is also an acceptable technique, and an easily determined point that is consistently close to the kinematic axis would simplify transfer of the arc of rotation from the patient to the articulator. PURPOSE: This in vivo study compared the location of an anatomically predetermined hinge axis point with the determined kinematic axis. MATERIAL AND METHODS: Forty subjects (27 males, 13 females; 23 to 47 years of age) with functionally acceptable occlusion and no detectable clinical signs of temporomandibular disorders participated in the study. The earpiece alignment flags on a mechanical SAM Axiograph III combination flag/face-bow were used to locate the right and left predetermined hinge axis points, 10 mm anterior to the earpiece. The right and left kinematic center of rotation was located as described by Lauritzen and confirmed with the PC Axiotron electronic Axiograph to within 0.25 mm. All points were transferred to 1 mm(2) grid paper on the subject's skin. The distance between each predetermined and kinematic point was measured +/-0.25 mm. Wilcoxon and Mann-Whitney tests were used to examine differences between the left and right axis points and potential significant differences between genders at a significance level of P<.05. The number of occurrences and the distance of the predetermined axis points from the kinematic axis also were described. RESULTS: The mean distance between points was 1.1 mm on the right (range 0.0 to 3.0 mm), 1.2 mm on the left (range 0.0 to 3.0 mm), and 1.1 mm for all 80 points (+/-0.63). More than 96% of the predetermined points were within 2 mm of the kinematic axis, and 67% were within 1 mm. There was no significant difference between the right and left points and no significant differences based on gender. CONCLUSION: Within the limitations of this study, the results suggest that the predetermined axis point is well within the clinical norm for estimated location of the transverse horizontal mandibular axis.
Adult↗
Combined long- and short-axis myocardial perfusion cardiovascular magnetic resonance.
PURPOSE: To date, myocardial perfusion cardiovascular magnetic resonance (CMR) has been reported in single and multiple short-axis slices. Three short-axis planes can assess 16 segments of the standard 17-segment myocardial model, but this approach fails to assess the ventricular apex that requires at least one long-axis plane. We therefore evaluated the feasibility and benefit of combined long- and short-axis perfusion CMR to enable complete 17 segments coverage for comprehensive myocardial perfusion assessment. METHODS AND MATERIALS: Using a hybrid echo planar imaging (EPI) sequence, we performed rest and adenosine stress first-pass perfusion CMR studies with 3 short-axis (basal, mid, apical) planes, and additional long-axis planes in the same cardiac cycle in a broad range of cardiology patients. RESULTS: Perfusion CMR was performed in 53 consecutive patients using the combined short-long-axis imaging protocol. Twenty-nine of those studied had known or suspected coronary artery disease (CAD), 18 hypertrophic cardiomyopathy, and 6 suspected microvascular perfusion abnormalities. In 39 patients (70%), it was possible to acquire 5 slices at rest and stress including both the horizontal and vertical long axes. In 15 patients (27%), only one long-axis could be acquired, and in 2 patients (5%) only 3 slices (short axis) could be obtained. However, in none of the patients with known or suspected CAD was apical ischemia demonstrated by the long-axis views, despite apical ischemia having been demonstrated with recent SPECT studies in 8 of these patients. CONCLUSION: Rest-stress myocardial perfusion CMR is able to achieve complete segmental coverage of the myocardium using the combined short-long axis approach using an EPI sequence in 97% of a long series of consecutive cardiology patients, while maintaining excellent spatial resolution. However, the long-axis views were not found to be able to demonstrate inducible perfusion defects in the apex.
Adult↗
Terminal 40-ms frontal plane QRS axis as a marker for tricyclic antidepressant overdose.
Tricyclic antidepressant (TCA) poisoning has been reported to cause a right-axis deviation of 130 degrees to 270 degrees in the terminal 40-ms frontal plane QRS axis (T40-ms axis) of the ECG. This retrospective cohort study was designed to determine if the T40-ms axis could discriminate TCA-toxic patients from other overdose patients and whether a correlation exists between TCA plasma concentration and T40-ms axis rotation. Only symptomatic overdose patients with plasma and urine drug screens and an ECG obtained within two hours of each other were included in the study. Patients were divided into two groups: TCA overdose patients (TCA OD, n = 48) and nonTCA overdose patients (nonTCA OD, n = 30). The mean T40-ms axis was significantly more rightward in the TCA OD group compared with the nonTCA OD group (179 +/- 74 vs 86 +/- 87, P less than .001). A TCA OD patient was 8.6 times more likely to have a T40-ms axis of more than 120 degrees than was a nonTCA OD patient (odds ratio, 8.6; 95% confidence interval, 2.7 to 29.1). Eight of the TCA poisoned patients (17%) did not demonstrate a T40-ms axis between 120 degrees and 270 degrees. Receiver operating characteristics demonstrated that the T40-ms axis was a better indicator of TCA toxicity than the QRS interval (P less than .05). A T40-ms axis of 120 degrees or more was 83% sensitive and 63% specific for TCA overdose. A correlation between plasma TCA concentration and T40-ms axis deviation was not found (r = .04).(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Abnormal fetal cardiac axis in the detection of intrathoracic anomalies and congenital heart disease.
In a 14-month period, 409 women with singleton gestations referred for perinatal ultrasound consultation underwent evaluation of the fetal cardiac axis. Cardiac and intrathoracic anomalies were confirmed either by neonatal echocardiography or autopsy. Overall, 32 fetuses had an abnormal axis (nine, smaller axis than normal; 23, larger axis than normal). Of the 29 found to have cardiac (n = 24) or intrathoracic (n = 5) anomalies, 23 had an abnormal axis. The median cardiac axis of the normal group (44.0 degrees) was significantly smaller than that of the cardiac/intrathoracic anomaly group(60.0 degrees) (p = 0.002). The cardiac axis was independent of gestational age. The mean interobserver variation was 1.3 +/- 1.8 degrees. The sensitivity of an abnormal axis (< 28 degrees or > 59 degrees) in detecting congenital heart disease or intrathoracic anomalies was 23/29 (79.3%), with specificity of 371/380 (97.5%), positive predictive value of 23/32 (71.9%), and negative predictive value of 371/377 (98.4%). Of those with a cardiac anomaly and an abnormal axis (n = 18), five were felt to have an initial normal four-chamber view. An abnormal fetal cardiac axis, either larger or smaller than normal, is suggestive of a cardiac or intrathoracic anomaly and requires further investigation, such as fetal echocardiography. The cardiac axis should be considered with the four-chamber view in fetal ultrasound evaluation.
Adult↗
Femoral rotational alignment using the tibial shaft axis in total knee arthroplasty.
The capability of determining femoral component rotation by using a posterior femoral condyle resection made perpendicular to the longitudinal tibial shaft axis in posterior cruciate retaining total knee arthroplasty was evaluated. From 100 consecutive cases, 54 used the femoral posterior condyle axis and 46 used an extramedullary alignment rod based on the tibial shaft axis. Seventy-two percent of total knee arthroplasties using the posterior condyle axis required lateral release versus 28% using the tibial shaft axis. Patellar fracture occurred in 7% using the posterior condyle axis versus none using the tibial shaft axis. Two patients had both techniques in opposite knees. Using computed tomography, the posterior condyle axis method gave a posterior condyle angle of 5 degrees and 4 degrees compared with the transepicondylar axis, whereas the tibial shaft axis technique measured 0 degrees and 1 degree. The posterior condyle resection using the tibial shaft axis restores the anatomic patellofemoral relationships, minimizing patellofemoral complications.
Adult↗
Correction of pixel sensitivity variation and off-axis response for amorphous silicon EPID dosimetry.
The aim of this work is to determine the pixel sensitivity variation and off-axis dose response of an amorphous silicon electronic portal imaging device (EPID), and develop a correction method to improve EPID dosimetry. The uncorrected or raw pixel response of the aS500 amorphous silicon EPID shows differences in response (sensitivity) of individual pixels as well as a large off-axis differential response with respect to an ion chamber in water. Both can be corrected by division of raw images by the flood-field (FF) image. However, this leads to two problems for dosimetry: (1) the beam profile is present in both the raw image and FF image, and hence is "washed out" of the corrected image, and (2) any mismatch of EPID position between dosimetry and FF calibration means that the beam profile and off-axis response in the raw image and FF are misaligned. This causes artifacts in FF division and dosimetric errors. A method was developed to measure the off-axis response and pixel sensitivity variation separately to allow correction of images at any EPID position while retaining beam profile information. The pixel sensitivity variation is applied to the imager plane and is independent of imager position. The off-axis response depends on the imager plane position relative to the beam central axis. The pixel sensitivities were derived from multiple images of the same symmetric field acquired with the detector displaced laterally between each image. The off-axis response was measured by acquiring off-axis raw images (FF correction removed) and dividing out the off-axis beam fluence and previously determined pixel sensitivity differences. The dosimetric errors due to lateral and vertical detector displacement with the conventional FF calibration method were measured and compared to the new method. Corrected EPID profiles were then compared to beam profiles measured with ion chamber in water for open fields. The EPID was found to have a large off-axis differential response with respect to an ion chamber in water, particularly for 6 MV. This increased to 13% at 15 cm off-axis for 6 MV, and 3.5% for 18 MV at the isocenter plane. The dosimetric errors introduced by detector displacement with conventional FF calibration were found to be approximately 1% per centimeter of lateral detector displacement and 0.1% per centimeter of vertical displacement. These were reduced to less than 1% for any position with the new correction method. Corrected EPID images agreed with ion-chamber measurements to within 2% (excluding penumbra and low-dose areas outside the field) for various field sizes. The new correction method gives consistent dosimetry for any EPID position and retains beam profile information in the image.
Biophysical Phenomena↗
Functional importance of the long axis dynamics of the human left ventricle.
The role of longitudinally and circumferentially oriented fibres in left ventricular wall motion was examined by digitising echocardiograms of the mitral ring (whose motion reflects long axis change) and of the standard minor axis in 36 healthy individuals, 36 patients with coronary artery disease, 16 with left ventricular hypertrophy, 44 with mitral valve disease (24 of whom had undergone mitral valve replacement). In the controls long axis shortening significantly preceded minor axis shortening (mean (1 SD) difference 25 (40) ms) so that the minor axis increased more during isovolumic contraction (0.25 v 0.09 cm), indicating that the left ventricle became more spherical. Changes in the long and short axes were synchronous at end ejection and in early diastole in the controls. Epicardial excursion preceded endocardial excursion by 50 (20) ms at its peak. These time relations were consistently disturbed in all patient groups, irrespective of the extent of fractional shortening of the minor axis. The onset of long axis shortening was delayed, and this was often associated with premature shortening of the minor axis, the normal spherical shape change during isovolumic contraction was lost, and peak epicardial and endocardial changes became more synchronous. In patients with coronary disease these changes are the expected consequence of ischaemic injury to longitudinally orientated subendocardial fibres. In left ventricular hypertrophy their presence consistently showed systolic dysfunction when orthodox measures were still normal. They were more pronounced after mitral valve replacement when the papillary muscles had been sectioned; long axis shortening was reduced during systole and prolonged into early diastole, while normal shortening of the minor axis was maintained only by abnormal epicardial excursion. Relations between long and short axis motion in healthy individuals are characteristic, and their loss is an early index of systolic ventricular disease. These disturbances precede changes in orthodox measures such as fractional shortening or peak velocity of circumferential fibre shortening.
Cardiomegaly↗