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PubMed1997

Reduced cortical responses to noxious heat in patients with rheumatoid arthritis.

OBJECTIVES: To test the hypothesis that patients with chronic inflammatory pain develop adaptive cortical responses to noxious stimulation characterised by reduced anterior cingulate responses. METHODS: Positron emission tomography was used to measure changes in regional cerebral blood flow (rCBF) in response to an acute experimental pain stimulus in six patients with rheumatoid arthritis (RA) in comparison to six age and sex matched controls. A standardised and reproducible non-painful and painful phasic heat stimulus was delivered by a thermal probe to the back of the right hand during six two minute periods during which time rCBF measurements were made. The effects of non-painful heat were subtracted from those of painful heat to weight the analysis towards the non-discriminatory or 'suffering' components of pain processing. Significance maps of pain processing were generated and compared in each group and contrasted with results obtained in a group of patients with atypical facial pain (AFP) that have been previously published. RESULTS: The RA patients showed remarkably damped cortical and subcortical responses to pain compared with the control group. Significant differences between the two groups were observed in the prefrontal (BA 10) and anterior cingulate (BA 24) and cingulofrontal transition cortical (BA 32) areas. The reduced anterior cingulate responses to standardised heat pain were compared with the increased cingulate responses seen in patients with psychogenically maintained pain (AFP) who had both lower pain tolerance and mood than the RA group. CONCLUSIONS: Major cortical adaptive responses to standardised noxious heat can be measured and contrasted in patients with different types of chronic pain. The different pattern of cingulate and frontal cortical responses in the patients with inflammatory and non-nociceptive pain suggest that different mechanisms are operating, possibly at a thalamocortical level. Implications for treatment strategies for chronic pain are discussed.

Adaptation, Physiological↗
PubMed2006

Manic behaviour induced by deep-brain stimulation in Parkinson's disease: evidence of substantia nigra implication?

We report the case of a patient who had benefited from bilateral subthalamic nucleus deep brain stimulation for Parkinson's disease and who presented acute and reproducible manic behaviour when stimulated mainly in the substantia nigra. A positron emission tomography scan showed an activation of the right dorsolateral prefrontal and inferior temporal cortex, the left anterior cingulate cortex and a deactivation of the left insula. This suggests that changes in cortical activation related to mania are subcortically driven, involving notably the substantia nigra.

Bipolar Disorder↗
PubMed1997

Coronary sinus pacing prevents induction of atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is due to reentry, and its incidence has been shown to decrease after dual-site atrial or biatrial pacing. We investigated whether a simpler pacing approach via the distal coronary sinus (CSd) could eliminate AF inducibility by high right atrial (HRA) extrastimuli (APDs). We based our hypothesis on our previous observation that AF inducibility by HRA APDs was associated with conduction delays to the posterior triangle of Koch, whereas AF was never induced with CSd APDs, which were associated with minimal intra-atrial conduction delays. METHODS AND RESULTS: Programmed electrical stimulation was performed from the high right atrium and CSd, and bipolar recordings were obtained from the high right atrium, His bundle, posterior triangle of Koch, and coronary sinus. In 13 patients (age, 44+/-18 years), AF was reproducibly induced with a critically timed HRA APD (220+/-22 ms) delivered during HRA pacing. AF was not induced in any of the patients when HRA APDs were delivered during CSd pacing at the same critical coupling intervals. Coronary sinus APDs delivered during HRA pacing also were not associated with AF induction. The APD coupling interval measured at the posterior triangle of Koch during CSd pacing was significantly prolonged compared with the one measured during HRA pacing and AF induction (381+/-58 versus 263+/-37 ms; P<.0001). CONCLUSIONS: We propose that CSd pacing suppresses the propensity of HRA APDs to induce AF by limiting their prematurity at the posterior triangle of Koch and not allowing local conduction delay and local reentry to occur.

Adolescent↗
PubMedDate not supplied

Improved method for noninvasive measurement of regional cerebral blood flow by 133Xenon inhalation. Part I: description of method and normal values obtained in healthy volunteers.

A clinical method for noninvasive measurement of regional cerebral blood flow (rCBF) and blood volume (rCBV) is described, based on Obrist's 10 minute, desaturation method after 1 minute inhalation of 133Xe. Sixteen collimated probes are placed over both hemispheres and brain stem-cerebellar regions. End-tidal 133Xe curves are used for correction of recirculation. KEV discriminators are set to record gamma and x-ray activity separately. Values are printed out automatically by a computer on a brain map. Extracerebral contamination is reduced by 1) computing curves from gamma activity, 2) applying pressure on the scalp beneath the probes, 3) 1 minute inhalation of 133Xe and recording desaturation curves for 10 minutes, thereby minimizing slow clearance from extracranial tissues. Normal values for both fast and slow compartments are reproducible and are in good agreement with the carotid injection method. The speech dominant hemishpere has higher flow than the right under conditions described. Posterior portions of the cranium over the cerebellum and brain stem appear to have higher flow gray values than the cerebral cortex. Gray matter flow decreases with advancing age.

Adult↗
PubMedDate not supplied

Relationship of the ECG with ventilatory function tests in chronic obstructive lung disease (COLD) in Nigerians.

Although the most objective assessment of the severity of COLD is done by spirometer, this is not as readily available in Nigeria as the electrocardiograph, thus the ECG is often used to assess it. This study examines the relationship between the ECG findings and FEV 1 obtained by spirometry and expressed as a proportion predicted for age and sex in 92 Nigerians with COLD of which 39 had associated pulmonate. There was an inverse relationship between the mean electrical axis of the P wave on the ECG and the FEV 1 of predicted. The axis was more positive (82 +/- 12 degrees) among those with FEV 1 less than 50% of predicted (group 1) and this decreased progressively with increasing FEV 1 to 72 +/- 14 degrees in those with FEV 1 between 50-70% (group 2) and 67 +/- 16 degrees in those with FEV 1 greater than 70% (group 3). There was also a significant relationship between FEV 1 and the development of cor pulmonale and 71.4% of those who had the lowest FEV 1 (group 1) had cor pulmonale while the proportion decreased with the reduction in the severity of airway obstruction. A rightward P wave axis greater than 80% was statistically significant associated with development of cor pulmonale (X2 = 29.5 (P < 0.001) of those with COLD and cor pulmonale, 72.2% had a P wave axis greater than 80%. Only 13.2% of those with COLD alone had a P wave axis greater than 80 degrees. Cardiac arrhythmias were present in 28 patients, ventricular (VA) in 23 cases, and atrial (AA) in 7 cases. Both AA and VA were associated with more severe airway obstruction. All 3 patients who had atrial fibrillation (AF) and FEV 1 below 50% of predicted (group 1) and had cor pulmonale while 2 of the remaining 4 with AA also were in group 1 and the remaining 2 in group 2. The distribution of ventricular arrhythmias (VA) showed that 10 (43.5%) were in group 1, 9 (39.1%) in group 2, and 2 (8.7%) in group 3. Both VA and AA were also significantly related to the development of cor pulmonale. A P wave amplitude greater than 2.5 mm was significantly related to the development of clinical cor pulmonale X2 = 24.6 P < 0.001. The results show that ECG findings correlate well with spirometric assessments of FEV 1 and clinical severity in Nigerians with COLD and are, therefore, useful where spirometry is unavailable.

Adult↗
PubMed1997

How reproducible are measures of the anal sphincter muscle diameter by endoanal ultrasound?

UNLABELLED: Anal endosonography is an imaging technique for the anal sphincter system and offers analysis of its muscular integrity. It is generally assumed that measurement of the thickness of muscle layers is provided by sonography; however, reproducibility of such measurements have not yet been investigated. METHODS: Study 1: In 10 healthy volunteers, endoanal ultrasound was performed independently by two experienced investigators with two different ultrasound machines, and thickness of the muscle layers of the internal and external anal sphincter was assessed in the position of the intermediate dorsal anal canal in a randomized cross-over fashion. Study 2: In a study of similar design, sonography was performed in nine healthy volunteers by two investigators independently using a single ultrasound machine in three standardized positions (proximal/intermediate/distal anal canal) and the sphincter layers assessed in the left, right, and dorsal segment. RESULTS: Study 1: Both the same investigator with different ultrasound scanners and different investigators with the same machine failed to obtain reproducible results with respect to internal and external anal sphincter muscle layer diameter (four bivariate correlations, all with p > 0.05). Study 2: Standardization of the probe position did not improve the agreement (2 x 9 bivariate correlations, all but two p > 0.05). CONCLUSION: At present, therefore, endoanal ultrasound does not provide reliable morphometric data on anal sphincter muscle diameter. This could explain previously conflicting observations of associations between anal sphincter morphometry and function.

Anal Canal↗
PubMedDate not supplied

Innovative techniques in skeletal muscle cardiac assistance: first experimental study on minimally invasive aortomyoplasty and cardiomyoplasty.

Skeletal muscle cardiac assistance as a treatment modality for heart failure is considered a high-risk procedure subject to strict patient selection. The aim here is to develop minimally invasive techniques to improve surgical outcomes and increase clinical indications. Ten goats (45-55 kg) were studied. In six, the latissimus dorsi muscle (LDM) was harvested via an open technique on one side vs a minimally invasive technique on the other using video assistance through two 3 cm incisions. Surgical maneuvers and length of procedures were noted. Animals were recovered, observed daily for local complications, and killed after 1 week for comparative anatomic and histopathologic studies. In four other goats, minimally invasive aortomyoplasty or cardiomyoplasty was performed using video assistance (2 aortomyoplasty, 2 cardiomyoplasty). In this experimental series, there were no surgical complications. The minimally invasive LDM harvest required a mean of 81 min (range 55-116 mn) with no gross evidence of muscle damage. The technique of LDM harvesting was standardized and is reproducible. Aortic and cardiac wraping were also achieved through three ports and a left minithoracotomy of 4 cm, using the right or left LDM. A scarf technique for the descending aortomyoplasty using the left LDM, and an anterior wrapping for cardiomyoplasty using the left or right LDM was technically feasible with video assistance. This study suggests future clinical applicability.

Animals↗
PubMed2007

Event-related functional near-infrared spectroscopy (fNIRS) based on craniocerebral correlations: reproducibility of activation?

The purpose of the present study was to assess the retest reliability of cortical activation detected by event-related functional near-infrared spectroscopy (fNIRS) based on craniocerebral correlations. Isolated functional activation was evoked in the motor cortex by a periodically performed finger-tapping task. During 44-channel fNIRS recording, 12 subjects performed 30 trials of right and left index finger tapping in two sessions. The retest interval was set to 3 weeks. Simple correlations of the contrast t-values supplemented by scatterplots, channel-wise intraclass correlation coefficients (ICC), as well as reproducibility indices for the size and the location of the detected activation were calculated. The results at the group level showed sufficient single measure ICCs (up to 0.80) and excellent reproducibility of the size and the location (up to 89% were reproducible). Comparisons of the intersession group amplitudes demonstrate that the fNIRS signals were stable across time in a retest study design: the number of significant differences was less than randomly occurring false-positive activated channels if an alpha level of 5% is chosen. Effect size analyses indicated that the intersession amplitude differences are small (mean < 0.25). For deoxyhemoglobin and oxyhemoglobin distinct statistical power profiles were revealed regarding the activation vs. baseline contrast as well as the intersession amplitude differences, indicating a higher sensitivity of deoxyhemoglobin for local hemodynamic changes. The results suggest that sensorimotor activation assessed by event-related fNIRS based on craniocerebral correlations is sufficiently reproducible at the group level.

Adult↗
PubMed1996

The topographic representation of esophageal motor function on the human cerebral cortex.

BACKGROUND & AIMS: Corticofugal pathways to the human esophagus have been recently identified in humans using transcranial magnetic stimulation. The aim of this study was to determine the topographic representation of the esophagus on the cerebral cortex. METHODS: Focal magnetic stimulation of 1-cm areas was performed over both hemispheres in 10 healthy subjects. Esophageal electromyographic responses were recorded 2 cm below the upper esophageal sphincter. The studies were repeated to determine reproducibility in 3 subjects; in 2 subjects, esophageal topography was compared with thenar muscle topography. RESULTS: In all subjects, esophageal electromyographic responses were evoked by stimulation of either the right or left hemisphere. Largest amplitude responses were obtained anterior to those of the thenar muscles, indicating that the esophagus may be represented on either the anterior aspect of the motor cortex or on the premotor cortex. In all subjects, the area of response was asymmetric, being more extensive on the right hemisphere than on the left hemisphere in 8 subjects. In 2 subjects, the area of response on the left hemisphere was more extensive than on the right. Repeat studies showed that this asymmetry was consistent. CONCLUSIONS: Esophageal motor function shows bilateral cortical representation with consistent interhemispheric asymmetry.

Adult↗
PubMed2002

Thoracolumbar proprioception in individuals with and without low back pain: intratester reliability, clinical applicability, and validity.

STUDY DESIGN: Repeated measures design of active spinal position sense in individuals with and without low back pain (LBP). OBJECTIVES: Reproducibility and validity evaluation of thoracolumbar proprioception measurement. BACKGROUND: Proprioception studies in peripheral joints and the spine suggest that there may be proprioception deficits due to injury, pain, or degeneration. Kinesthetic retraining may be useful in rehabilitation of patients with LBP, but appropriate measures are required to objectively quantify spinal proprioception. METHODS AND MEASURES: Active-target reproduction in the sagittal, horizontal, and coronal planes was assessed (3 separate occasions for 18 asymptomatic volunteers and 2 occasions for 62 patients with LBP). Repositioning accuracy was expressed as absolute errors (AE) and variable errors (VE). Reliability was analyzed with intraclass correlation coefficient (ICC) and precision with standard error of measurement (SEM) and calculation of the smallest detectable difference (SDD) index. Repeated measures ANOVA and correlations were used for within-group comparisons and discriminant analysis for between-group comparisons. RESULTS: Reproducibility was better for the asymptomatic group, with AE for flexion and rotation being the most reliable (ICC = 0.76-0.80, SEM = 0.91 degrees-1.34 degrees). SDDs were high for all tests, suggesting limited clinical applicability. Reproducibility for the same tests was poor-moderate (ICC = 0.31-0.64, SEM = 0.45 degrees-3.90 degrees) for the patient group. AE for right-side rotation could discriminate between subject groups with 83.3% specificity but only 54.8% sensitivity. CONCLUSIONS: Proprioception testing, with the methods employed, did not demonstrate good measurement properties in a sample of patients with recurrent LBP. Neither could it sufficiently discriminate between individuals with and without LBP. Possible reasons for these findings are discussed.

Adult↗
PubMedDate not supplied

Multifocal visual evoked potential is dependent on electrode position.

PURPOSE: To investigate whether the multifocal visual evoked potential (mVEP) is dependent on the electrode position, and to confirm the reproducibility of the mVEP. METHODS: The mVEPs were recorded using the Veris III system with two different bipolar electrode settings. In Position 1, electrodes were placed at equal distances in vertical alignment 2 cm above and below the inion. In Position 2, the electrodes were placed in horizontal alignment at equal distances 2 cm to the left and right of the inion. Dartboard pattern stimulation was conducted. The mVEPs were repeatedly recorded from 4 volunteers, and mainly the second-order kernel response components were analyzed. RESULTS: Although the reproducibility of mVEP was good in both Position 1 and Position 2, each waveform of the mVEP was drastically different between the two positions. This difference in the waveforms was clearly shown in the center and at the horizontal meridian. We also investigated the first-order kernel response components of the mVEPs. Several traces of the first-order kernel response components did not reveal flat traces. This point is also worthy of consideration. CONCLUSION: Responses from mVEPs are clearly dependent on the electrode position.

Adult↗
PubMed2005

The evaluation of pulmonary hypertension using right ventricular myocardial isovolumic relaxation time.

Right ventricular (RV) blood pool-derived isovolumic relaxation time (IVRT) correlates well with systolic pulmonary arterial pressure (PAP). However, because of complex parameter derivation, the method is rarely used. The aim of this study was to validate the measurement of myocardial velocity imaging-derived RV IVRT (IVRT') against invasively measured PAP. Transthoracic echocardiography with myocardial velocity imaging and right heart catheterization were performed in 33 patients with pulmonary hypertension. Blood pool IVRT and myocardial IVRTs for the tricuspid valve annulus ring, basal and apical RV free wall segments were measured and compared with data from 33 age- and sex-matched control subjects. Measured IVRTs were significantly longer in patients with pulmonary hypertension than in control subjects. The strongest correlation (R = 0.74, P < .0001) was found between systolic PAP and the heart rate-corrected IVRT' derived from the basal RV free wall segment. The basal segment IVRT' corrected for heart rate correlates well with the invasive PAP measurement and, therefore, can be used to predict systolic PAP. It can even be considered as an alternative to tricuspid regurgitation-derived PAP systolic when tricuspid regurgitation is nonrecordable. A proposed method to derive systolic PAP should be used while screening the patients at risk for pulmonary hypertension, monitoring the disease progression and the effect of treatment.

Adult↗
PubMed2005

Color Doppler tissue imaging for evaluation of right ventricular systolic function in patients with congenital heart disease.

OBJECTIVE: We sought to explore the relationship of color Doppler tissue imaging-derived systolic indices of tricuspid valve annular motion and magnetic resonance imaging-derived right ventricular (RV) ejection fraction in patients with congenital heart disease. METHODS: Patients with congenital heart disease who underwent echocardiography and magnetic resonance imaging on the same day were included. The tricuspid valve annular color Doppler tissue imaging-derived parameters of peak velocity during isovolumic contraction, myocardial acceleration during isovolumic contraction, peak systolic velocity, and Tei index were compared with magnetic resonance imaging-derived RV ejection fraction. RESULTS: Peak systolic velocity and myocardial acceleration during isovolumic contraction correlated well with RV ejection fraction after adjusting for age, RV dilation, and pressure overload (r = 0.65 and 0.73, respectively). Interobserver and intraobserver reliability were excellent for peak systolic velocity (r = 0.95 and 0.97, respectively) and very good for myocardial acceleration during isovolumic contraction (r = 0.93 and 0.85, respectively). CONCLUSIONS: Color Doppler tissue imaging indices of tricuspid valve annular motion are reproducible and provide a potentially useful complementary tool for assessment of RV systolic function in patients with congenital heart disease.

Adolescent↗
PubMed2006

Novel mechanism of postinfarction ventricular tachycardia originating in surviving left posterior Purkinje fibers.

BACKGROUND: Other than bundle branch reentry and interfascicular reentry, monomorphic postmyocardial infarction (post-MI) reentrant ventricular tachycardia (VT) including the His-Purkinje system has not been reported. Verapamil-sensitive idiopathic left VT includes the left posterior Purkinje fibers but develops in patients without structural heart disease. OBJECTIVES: The purpose of this study was to describe a novel mechanism of reentrant VT arising from the left posterior Purkinje fibers in patients with a prior MI. METHODS: The study consisted of four patients with a prior MI and symptomatic heart failure who underwent electrophysiologic study and catheter ablation for VT showing right bundle branch block (n = 3) or atypical left bundle branch block (n = 1) morphology with superior axis. In two patients, the VT frequently emerged during the acute phase of MI and required emergency catheter ablation. RESULTS: Clinical VT was reproducibly induced by programmed stimulation. In three patients, both diastolic and presystolic Purkinje potentials were sequentially recorded along the left ventricular posterior septum during the VT, whereas in the fourth patient, only presystolic Purkinje potentials were observed. During entrainment pacing from the right atrium, diastolic Purkinje potentials were captured orthodromically and demonstrated decremental conduction properties, whereas presystolic Purkinje potentials were captured antidromically and appeared between the His and QRS complex. Radiofrequency energy delivered at the site exhibiting a Purkinje-QRS interval of 58 +/- 26 ms successfully eliminated the VTs without provoking any conduction disturbances. CONCLUSION: Reentrant monomorphic VT originating from the left posterior Purkinje fibers, which is analogous to idiopathic left VT, can develop in the acute or chronic phase of MI. Catheter ablation is highly effective in eliminating this VT without affecting left ventricular conduction.

Aged↗
PubMed2004

The feasibility of measuring three-dimensional facial morphology in children.

OBJECTIVE: An investigation to determine the feasibility of measuring soft tissue morphology in children using a three-dimensional laser-scanning device. DESIGN: Prospective clinical trial. SETTING AND SAMPLE POPULATION: University of Wales, College of Medicine and one secondary school in the South Wales region. Sixty live subjects (30 adults, 30 children) were recruited in the study. EXPERIMENTAL VARIABLES: Laser scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. OUTCOME MEASURE: The shell deviations between left and right scan of each patient were recorded and analysed for differences. These differences determined whether the subjects could remain still during the time of the scans. RESULTS: The results showed that the mean differences between shell deviations for the adult scans and children scans were 0.25 +/- 0.09 and 0.30 +/- 0.09 mm, respectively. Paired t-tests showed that the mean error between subject groups was 0.05 +/- 0.15 mm indicating that there was no difference between the two subject groups (p = 0.18). CONCLUSION: The technique as described is clinically reproducible for children and adults and can be used for studies assessing facial changes due to growth or clinical intervention.

Adult↗
PubMed1975

Extracardiac recordings of His-Purkinje activity during conduction disorders and junctional rhythms.

Previous investigations have demonstrated a surface recording technique using signal averaging to detect electrical activity during the "isoelectric" P-R segment. Various physiological and pharmacological interventions suggest that the source of these potentials isthe His-Purkinje system (HPS). In order to assess the sensitivity of averaged recordings to changes in HPS activation, i.e., conduction defects in the HPS recordings were made directly from the heart surface using a bipolar, anterior-posterior epicardial lead in 15 dogs which underwent thoractomy. The signal was amplified, filtered and averaged using a digital computer for purposes of signal enhancement. The epicardial averaged lead (EAL) contained activity coincident with HPS depolarization and similar to those recorded by leads on the body surface of intact dogs from previous studies. The standard ECG and His bundle electrogram from an electrode catheter served as references in localizing and assessing several conduction disorders experimentally produced by traumatic and ischemic injury. Among the disorders produced were: 1) atrioventricular (A-V) nodal block which resulted in loss of recorded activity in the EAL following the P wave. 2) First and second degree intra-His bundle block produced by anterior septal artery ligation showed split His potentials in the HBE (1 degree) and 2:1 conduction with block in the His bundle (2 degrees). In the blocked beats the EAL showed a reproducible portion of the activity coincident with proximal His bundle activity of the split His potentials in both cases. 3) In four cases of proximal right bundle branch block produced by anterior septal artery ligation the relatively proximal portions of HPS activity in the EAL showed marked diminution. 4) Two cases of distal His bundle or bilateral bundle branch delay were seen as prolonged H-V time and a normal QRS pattern. The early and late portions of the HPS activity in the EAL were not markedly changed while the middle portion was prolonged and fractionated. 5) Junctional rhythms produced by crushing the SA node resulted in no atrial activity occurring prior to HPS depolarization in the EAL. However, the QRS was preceded by HPS activity whose onset was coincident with the H recorded in the His bundle electrogram. The EAL showed consistent and reproducible morphology and timing of HPS activity at different heart rates during normal conduction and consistent alterations of the HPS activity during abnormal conduction.

Animals↗