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PubMed2004

The role of still-frame parametric imaging in magnetic resonance assessment of left ventricular wall motion by non-cardiologists.

BACKGROUND: Cardiac magnetic resonance (MR) images are often reviewed by non-cardiologists who are not trained in the interpretation of regional left ventricular (LV) function. We hypothesized that the use of still-frame parametric MR images of wall motion could aid in the assessment of regional LV function. METHODS: Dynamic, electrocardiogram-gated, steady-state free precession (FIESTA) short-axis images were obtained in 6 to 10 slices in 18 consecutive patients. Each loop was used to automatically generate a still-frame image, in which each pixel is assigned a value equal to the amplitude of cyclic variation in local intensity, resulting in higher intensity in pixels that change between blood and tissue during the cardiac cycle. The dynamic images were reviewed by an expert cardiologist who provided gold standard grades for regional wall motion and by four radiologists. Then the radiologists reviewed and graded the same MR images in combination with parametric images. Grades assigned to each segment in the two sessions were compared with the gold standard. RESULTS: According to expert interpretation, 6 patients had normal wall motion, and 12 had wall motion abnormalities. Parametric images showed a bright band in the area spanned by endocardial motion, with reduced brightness and thickness in areas of hypokinesis. The agreement between the radiologists' grades and the gold standard significantly improved by adding parametric images (from 77% to 81%), which also resulted in reduced interobserver variability (from 52% to 33%). CONCLUSIONS: Still-frame parametric images aid in the assessment of regional wall motion by non-cardiologists who are required to interpret cardiac images.

Female↗

PubMed1998

Determinants of regional myocardial function in patients with chronic significant coronary stenosis or occlusion.

BACKGROUND: Our aim was to study the effect of collateral flow, stenosis severity, antegrade flow, and location of the lesion on regional myocardial function in patients with chronic left anterior descending (LAD) coronary artery disease. METHODS AND RESULTS: Seventy-four patients who underwent coronary angiography and ventriculography were divided into three groups: group A (n = 9), patients with normal coronary angiogram and ventriculogram; group B (n = 32), patients with LAD stenosis >75%; and group C, 33 patients with LAD occlusion. The effect of collateral flow, stenosis severity, location, and antegrade flow on regional myocardial function in the LAD territory was studied. Regional function was impaired in both groups B and C. In group B, univariate analysis confirmed that antegrade flow had a significant effect on regional function (p < 0.02). With the use of multiple regression, none of the other variables had an additional independent effect. In group C, no significant correlation was found between regional function and the study variables by univariate analysis; however, multiple regression revealed a significant correlation between anterobasal function, the lesion site (p = 0.01), and collateral flow (p = 0.02). CONCLUSIONS: In patients with LAD stenosis, antegrade flow has the strongest effect on regional myocardial function, with no additional effect of visible collaterals. In patients with LAD occlusion, both angiographic collateral flow and the site of the lesion have a significant effect on the function of the anterobasal area.

Blood Flow Velocity↗

PubMed2004

The 10q24-linked split hand/split foot syndrome (SHFM3): narrowing of the critical region and confirmation of the clinical phenotype.

In this communication we describe the clinical and molecular genetic findings in a family with a variable ectrodactyly linked to SHFM3. This is only the second detailed report of the clinical features of the SHFM3 linked syndrome in a large pedigree. Within this family the expressivity of the condition ranges from the classical ectrodactyly deformity to partial absence of the thumb and agenesis of the distal tip of the index finger. There is discordant limb severity, with the feet more severely affected than the hands. Two individuals have a nail dysplasia indicating the presence of a minor ectodermal component. A cleft palate was present in one individual. Radiological features of family members include short metacarpals with rounded proximal heads, agenesis of the radial ray, epiphysial coning, and an unusual supernumerary ossicle opposed to the distal phalanx of the left thumb. Genetic mapping studies in this family exclude p63 involvement and demonstrate that ectrodactyly in this pedigree is linked to the SHFM3 region on chromosome 10q24. A meiotic recombination event enabled exclusion of a maximum of 1.9 Mb of DNA from the previously known critical region thereby narrowing the critical interval to between D10S1265 and D10S222, with the minimal critical region being between D10S1240 and D10S1267. Further investigations are in progress to identify the gene within the SHFM3 critical region responsible for ectrodactyly.

Abnormalities, Multiple↗

PubMed1989

Discrepancies between myocardial blood flow and fiber shortening in the ischemic border zone as assessed with video mapping of epicardial deformation.

Myocardial function around the border of ischemia was investigated in eight open-chest dogs using video mapping of epicardial deformation. With this method, 40-60 white markers attached to the left ventricular epicardium were traced in time automatically. Before and 5-10 min after coronary artery occlusion, blood flow and epicardial deformation were determined in 30-40 regions with a spatial resolution of about 5 mm. Epicardial deformation was expressed as subepicardial fiber shortening and surface area decrease during the ejection phase. The latter indicates local contribution to stroke volume. The absolute values of these variables were normalized relative to the central ischemic (= 0%) and remote non-ischemic area (= 100%). The 50% contour line of a variable was defined as its border. The average distance between the borders of perfusion and function was not significantly different from zero, due to considerable variation in this distance both within one heart (+/- 5.7 mm) and between mean distances for different hearts (+/- 4.4 mm). The width of the transition zone (distance between the 20% and 80% contour lines) of surface area decrease and subepicardial fiber shortening was significantly larger (20.5 and 15.0 mm, respectively) than those of transmural and subepicardial blood flow (8.5 and 9.5 mm, respectively). The present results demonstrate that in a 20-mm zone around the border of ischemia, major discrepancies are present between perfusion and deformation.

Animals↗

PubMed1989

Left subclavian flap aortoplasty for coarctation of the aorta: effects on forearm vascular function and growth.

This study evaluated vascular function and growth of the forearm in nine children (mean age 9.2 years) who had undergone left subclavian flap aortoplasty for the infantile type of coarctation of the aorta many years (mean 9.0) earlier. Variables used to investigate bilateral forearm vascular function included forearm blood flow and resistance measured by strain gauge plethysmography under rest conditions, in response to 30 s of static handgrip exercise at 40% maximal voluntary contraction and in response to 10 min of forearm arterial occlusion (that is, the reactive hyperemic blood flow response). Forearm growth was ascertained by measuring right and left forearm volumes, lengths, circumferences and skinfold thickness. Mean arterial pressure at rest in the right and left arms differed by 9% (right 78.2 +/- 2.1, left 71.0 +/- 2.7 mm Hg; p less than 0.05). Forearm blood flow, however, was not significantly different between the surgically altered left arm and the normal right arm under any of the study conditions. Likewise, forearm vascular resistance was not statistically different under any conditions, although the left arm tended to have a lower resistance at rest (right 23.5 +/- 3.2, left 18.7 +/- 2.0 mm Hg.min.100 ml/ml; p = 0.057). Left forearm anthropometric measurements showed a 9% reduction in volume and a 3% reduction in circumference and length. In addition, skinfold thickness tended to be larger on the left arm, suggesting that this limb had a smaller muscle mass. In conclusion, early repair with a subclavian flap does not impair vascular function in the altered limb and is associated with only minor reductions in forearm growth variables. Hence, left subclavian flap aortoplasty appears to be a safe and effective procedure for repair of coarctation of the aorta.

Aortic Coarctation↗

PubMed1996

Distributions and sources of magnetoencephalographic K-complexes.

Whole-head magnetoencephalographic (MEG) and midline electroencephalographic (EEG) signals were simultaneously recorded from 6 subjects during drowsiness and sleep to define the topography and source distribution of K-complexes. In light sleep, K-complexes were also triggered by infrequent tones. Distributions of spontaneous and triggered magnetic K-complexes did not differ systematically, nor did those evoked by right- and left-ear stimuli, but there were large intra- and interindividual differences. Minimum-norm estimates and current dipoles were used to characterize the source currents. Current direction and distribution varied remarkably between the K-complexes appearing in similar situations. In one subject, most K-complexes were adequately modelled with two current dipoles which were situated in the left and right inferior parietal lobes. In other subjects, the current distributions were more complex, suggesting several brain regions to be active during one K-complex; the dominant foci were in frontal and parietal lobes. Our results suggest that the K-complex is not a stereotyped response of the cortex to internal or external stimuli, comparable to evoked responses, but a diffuse and variable cortical reaction during which large areas of cortex may be active.

Adult↗

PubMed1999

Why does intermittent hydrostatic pressure enhance the mineralization process in fetal cartilage?

The purpose of this study was to determine which factor is the most likely one to have stimulated the mineralization process in the in vitro experiments of Klein-Nulend et al. (Arth. Rheum., 29, 1002-1009, 1986), in which fetal cartilaginous metatarsals were externally loaded with an intermittent hydrostatic pressure, by compressing the gas phase above the culture medium. Analytical calculations excluded the possibility that the tissue was stimulated by changes in dissolved gas concentration, pH or temperature of the culture medium through compression of the gas phase. The organ culture experiments were also mechanically analyzed using a poroelastic finite element (FE) model of a partly mineralized metatarsal with compressible solid and fluid constituents. The results showed that distortional strains occurred in the region where mineralization proceeded. The value of this strain was, however, very sensitive to the value of the intrinsic compressibility modulus of the solid matrix (Ks). For realistic values of Ks the distortional strain was probably too small (about 2 microstrain) to have stimulated the mineralization. If the distortional strain was not the factor to have enhanced the mineralization process, then the only candidate variable left is the hydrostatic pressure itself. We hypothesize that the pressure may have created the physical environment enhancing the mineralization process. When hydrostatic pressure is applied, the balance of the chemical potential of water across cell membranes may be disturbed, and restored again by diffusion of ions until equilibrium is reached again. The diffusion of ions may have contributed to the mineralization process.

Animals↗

PubMed2003

Dynamic event-related potentials and rapid source analysis reveals an intermittent short-lasting dysfrontality in schizophrenia.

Neuroimaging studies have identified regional brain dysfunctions in schizophrenia, but their dynamic consequences remain unclear. This study reports electrophysiological evaluation of medicated schizophrenic patients during performance of the Wisconsin Card Sorting Test. Using event-related potentials (ERPs), averaged after passing through several band pass filters, and source analysis with variable-resolution brain electrical tomography, cerebral sources were visualized at every latency point of the evoked potential. ERPs which differed from the control group were elicited principally in frontal, central, and parietal regions, within the delta and theta frequency ranges. Significant differences emerged at three different latencies (S1, S2, S3) in frontal/midline areas and at the anterior temporal electrode site T3 for slow potentials. The left occipitoparietal region showed significant differences within the alpha and beta 2 ranges, respectively. Medial fronto-orbital area and anterior cingulate cortex contributed to the development of the frontal ERPs and the lateral inferior frontal area to the temporal (T(3)) evoked-potential, while the precuneus/medial region generated the posterior activity recorded on the scalp. The significant intervals S1 and S3 were synchronous between the medial frontal and lateral inferior frontal region, while in the S2 interval the medial frontal areas were parallel with the precuneus/medial occipitotemporal region. A simultaneous functional imbalance between frontal subregions and posterior areas was uncovered. Here, we show for the first time an intermittent functional deficiency of specific brain areas during task-directed mentation in schizophrenia, which by its brevity is not accessible by neuroimaging methods measuring hemodynamic activity.

Adult↗

PubMed1989

Myocardial surface PO2--an indicator of myocardial tissue oxygenation?

The validity of myocardial surface tissue PO2 (PtO2) as a reliable indicator of transmural myocardial tissue oxygenation was studied in six anaesthetised, open chest pigs. Epicardial surface PtO2 was correlated with other variables of myocardial tissue oxygenation such as regional blood flow, coronary venous PO2, O2 saturation, PCO2 and regional myocardial lactate extraction. The study design was based on an experimental model in which the effects of a pacing induced tachycardia on tissue oxygenation of ischaemic and normally supplied myocardium were measured. Two platinum multiwire surface electrodes were placed on the epicardium, on the areas supplied by the left anterior descending coronary artery (LAD) and the left circumflex coronary artery (CX). The LAD was constricted to reduce mean surface PtO2 in the LAD area to about 50% of its baseline value. This did not affect surface PtO2 in the CX area. The reduction of surface PtO2 in the LAD area was associated with decreases in coronary venous PO2 and O2 saturation and with increases in coronary venous lactate and PCO2. Subendocardial regional blood flow and the subendocardial to subepicardial flow ratio were significantly lower than in the CX area. Increasing the heart rate by pacing (+45 beats.min-1) led to an increased degree of ischaemia as shown by fall in surface PtO2 in the LAD area to values around zero kPa, by marked increase in coronary venous lactate and PCO2, by reduction in total (-10%) and subendocardial (-40%) LAD flow and by deterioration of the subendocardial to subepicardial flow ratio. The increased degree of ischaemia was not accompanied by an increase in O2 extraction. The marked decrease in surface PtO2 occurred in spite of a slight increase in the subepicardial regional blood flow (+10%); thus the increase in O2 delivery was not sufficient to meet the increase in O2 demand. Total flow was increased by 27% in the CX area without changes in the subendocardial to subepicardial flow ratio and in the surface PtO2 values. When pacing was stopped, surface values of PtO2 in the LAD area returned to prepacing values, as did lactate extraction and coronary venous PCO2. Clear and close relationships with surface PtO2 were found for regional lactate extraction, coronary venous PCO2 and the normalised subendocardial RBF. Poor or no correlations were found for the normalised subepicardial regional blood flow, the coronary venous O2 saturation and the absolute values of subendocardial and subepicardial regional blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1993

Regional blood volume distribution during positive and negative airway pressure breathing in supine humans.

To assess the effects of continuous positive (CPAP) or negative airway pressure (CNAP) breathing (+/- 10-12 cmH2O, duration 25 min) on blood content in the body's capacitance vasculature, regional distribution of labeled red blood cells was evaluated in seven spontaneously breathing supine volunteers. Counts were acquired by whole body scans and detectors overlying the liver, intestine, left ventricle, and lower arm, and arterial pressure, heart rate, calf blood flow and vascular resistance, hematocrit, vasopressin, and atrial natriuretic peptide plasma concentrations were also obtained. With CPAP, thoracic, cardiac, and left ventricular counts diminished significantly by 7-10%, were accompanied by significant increases in counts over both the gut and liver, and remained decreased during CPAP but reversed to baseline with zero airway pressure. Calf blood flow and vascular resistance significantly decreased and increased, respectively, whereas limb counts, arterial pressure, heart rate, and hormone concentrations remained unchanged. With CNAP, in contrast, regional counts and other variables did not change. Thus, moderate levels of CPAP deplete the intrathoracic vascular bed and heart, shifting blood toward the gut and liver but not toward the limbs. No short-term compensation increasing cardiac filling during CPAP was seen. In contrast, CNAP did not alter intrathoracic or organ blood content and, therefore, does not simply mirror the effects evoked by CPAP.

Adult↗

PubMed2002

Beneficial effects of therapy on the progression of structural remodeling during healing after reperfused and nonreperfused myocardial infarction: different effects on different parameters.

BACKGROUND: Structural left ventricular remodeling after myocardial infarction is a complex process with several pathophysiologic descriptors that can be modified by pharmacotherapy. However, the possibility that different classes of antiremodeling agents might exert different effects on different remodeling parameters after reperfused and nonreperfused myocardial infarction has not been systematically studied. METHODS AND RESULTS: We measured detailed left ventricular remodeling parameters in vivo (echocardiograms) repeatedly over 6 weeks and ex vivo (planimetry) at 6 weeks after myocardial infarction in 36 dogs randomized (factorial design) after reperfused or nonreperfused myocardial infarction to 6 weeks of twice daily oral therapy with the calcium channel blocker amlodipine (5 mg), the angiotensin-converting enzyme inhibitor enalapril (5 mg) or placebo, and 18 matching sham or control animals. Compared to placebo and control groups over 6 weeks, both agents reduced left ventricular loading and limited overall remodeling in both reperfused and nonreperfused groups, but there were pertinent differences. Enalapril limited the increase in left ventricular asynergy in the reperfused group. Both enalapril and amlodipine limited infarct zone thinning in the nonreperfused groups but increased infarct zone thinning in the reperfused groups, despite preserved infarct zone collagen with amlodipine. Enalapril decreased left ventricular diastolic volume and mass more than amlodipine in the reperfused group and increased left ventricular ejection fraction in the nonreperfused group. Both agents limited regional and global shape deformation in reperfused and non-reperfused groups. Diastolic wall stress in the infarct zone decreased with amlodipine, and increased with enalapril and reperfusion. CONCLUSIONS: Different antiremodeling therapies may exert different effects on different remodeling parameters during healing after reperfused myocardial infarction. Significant interactions occur during reperfusion. More than one variable may be needed for the comprehensive assessment of the antiremodeling efficacy of different therapies.

Amlodipine↗

PubMed1982

The afferent and efferent callosal connections of retinotopically defined areas in cat cortex.

We compared the callosal afferent and efferent connections of different retinotopic loci within a given visual cortical area as well as the connectivity patterns among similar retinotopic loci in different visual areas. Small injections (75 nl) of a mixture of horseradish peroxidase and [3H]leucine were made through a recording pipette at injection sites identified by retinotopic mapping. A small locus of cortex within a callosally connected region had precise reciprocal connections with the homotopic locus in the contralateral hemisphere. This small locus also was callosally connected with a variable number of heterotopic loci. Both reciprocal and nonreciprocal heterotopic callosal connections were found. Homotopic and heterotopic connections appeared to have a high degree of retinotopic fidelity. Precisely homotopic connections were present not only between locations on the vertical meridian representations at the left and right area 17/18 borders but also, for example, between mirror-symmetrical points on the peripheral horizontal meridian representation in the left and right posteromedial lateral suprasylvian areas. In several experiments, we found that both callosal neurons and terminals in the homotopic cortex were grouped into two to three distinct clusters ranging from 600 to 900 micrometers in width. Callosal neurons with homotopic connections were primarily pyramidal cells in lower layer III and upper layer IV. Outside of areas 17 and 18, there was a significant number of pyramidal and fusiform-shaped callosal neurons in layers V and VI. The majority of callosal terminals were located in layers II, III, and IV.

Afferent Pathways↗

PubMed1998

Combined assessment of myocardial perfusion and left ventricular function with exercise technetium-99m sestamibi gated single-photon emission computed tomography can differentiate between ischemic and nonischemic dilated cardiomyopathy.

The purpose of this study was to determine whether exercise technetium-99m sestamibi gated single-photon emission computed tomography (SPECT) accurately distinguishes between patients with ischemic cardiomyopathy and patients with nonischemic left ventricular systolic dysfunction. Noninvasive tests have previously failed to accurately separate patients with ischemic cardiomyopathy from those with nonischemic cardiomyopathy. Technetium-99m gated SPECT imaging offers advantages that have the potential to overcome the limitations of previous studies. Thirty-seven adults with a left ventricular ejection fraction < or = 35%, including 24 patients with nonischemic cardiomyopathy and 13 patients with ischemic cardiomyopathy, were prospectively evaluated using symptom-limited metabolic exercise treadmill testing with technetium-99m sestamibi gated SPECT imaging. Interpretation of myocardial perfusion and regional wall motion was performed, using a 17-segment model. Summed stress, rest, and reversibility perfusion defect scores were determined, and the variance of segmental wall motion scores was computed. Summed stress, rest, and reversibility perfusion defect scores were significantly lower in nonischemic cardiomyopathy patients, compared with those with ischemic cardiomyopathy (summed stress defect score: 6.9 +/- 3.8 vs 32.9 +/- 7.7, respectively, p <0.001). Variability in segmental wall motion was also significantly lower in patients with nonischemic cardiomyopathy compared with those with ischemic cardiomyopathy (variance: 0.3 +/- 0.3 vs 1.2 +/- 0.8, respectively, p <0.001). Thus, assessment of myocardial perfusion and regional ventricular function with exercise technetium-99m sestamibi gated SPECT imaging can reliably distinguish between patients with ischemic cardiomyopathy and patients with nonischemic dilated cardiomyopathy.

Adult↗

PubMed2006

Role of regional mechanical dyssynchrony as a determinant of functional mitral regurgitation in patients with left ventricular systolic dysfunction.

OBJECTIVE: To assess regional mechanical dyssynchrony as a determinant of the degree of functional mitral regurgitation (FMR). SETTING: Tertiary cardiology clinic. PATIENTS: 74 consecutive patients with left ventricular (LV) dysfunction (ejection fraction < 40%, mean 32.2 (SD 7.3)%) were evaluated. METHODS: Effective regurgitant orifice (ERO) area, indices of mitral deformation (systolic valvular tenting, mitral annular contraction) and of global LV function and remodelling (ejection fraction, end systolic volume, sphericity index) and local remodelling (papillary-fibrosa distance, regional wall motion score index), and tissue Doppler-derived dyssynchrony index (DI) (regional DI, defined as the standard deviation of time to peak myocardial systolic contraction of eight LV segments supporting the papillary muscles attachment) were measured. RESULTS: All the assessed variables correlated significantly with ERO. By multivariate analysis, systolic valvular tenting was the strongest independent predictor of ERO (R(2) = 0.77, p = 0.0001), with a minor influence of papillary-fibrosa distance (R(2) = 0.77, p = 0.01) and regional DI (R(2) = 0.77, p = 0.03). Local LV remodelling (regional wall motion score index: R(2) = 0.58, p = 0.001; papillary-fibrosa distance: R(2) = 0.58, p = 0.002) and global remodelling indices (sphericity index: R(2) = 0.58, p = 0.003) were the main determinants of systolic valvular tenting, whereas regional DI did not enter into the model. Regional DI was an independent predictor of ERO (R(2) = 0.56, p = 0.005) in patients with non-ischaemic LV dysfunction but not in patients with ischaemic LV dysfunction when these groups were analysed separately. CONCLUSIONS: The degree of FMR is associated mainly with mitral deformation indices. The regional dyssynchrony also has an independent association with ERO but with a minor influence; however, it is not a determinant of FMR in patients with ischaemic LV dysfunction.

Cardiac Output↗

PubMed2002

Lateralized mineral content and density in distal forearm bones in right-handed men and women: relation of structure to function.

To test whether handedness has an asymmetric effect on distal forearm bone mineral content (BMC) and bone mineral density (BMD), and whether there is an effect of sex on these variables, the mean BMCs and BMDs in bilateral distal forearms were compared in right-handed men and women. It was expected that the BMC and BMD would be higher on the right than the left side in right-handers. The present results were consistent with this working hypothesis. Namely, the right-BMCs were found to be significantly higher than left-BMCs for all regions of the bones studied. There were no sex differences either for the right-left BMCs or for the right-left BMDs. The results indicated that i) the relation of structure to function would also be valid outside the brain, ii) the mean BMCs, but not BMDs, were significantly higher in the right than the left arm at different distal forearm regions, and iii) there were no significant sex differences in the distal-forearm BMCs and BMDs.

Adult↗

PubMed1995

Intra-articular pressure, elastance, and range of motion in flexion of the equine metacarpophalangeal joint.

A study was done to determine whether intra-articular pressure is increased in equine metacarpophalangeal joints with increasing degrees of synovial distention, and to correlate elastance of the soft tissue forming the dorsal pouch of the metacarpophalangeal joint to maximal range of motion in flexion. Sixty seven metacarpophalangeal joints in 36 horses were categorized by palpation and visual inspection of the palmar pouch into 1 of 4 increasing grades of distention. Intra-articular pressures were then measured, using 2 pressure transducers attached to 22 gauge needles, from the dorsal and palmar pouches simultaneously while horses stood squarely under mild sedation. Intra-articular pressure ranged from -13 to +78 mm of Hg. Mean (+/- SEM) palmar pouch pressure was subatmospheric (-2.53 +/- 2.78 mm of Hg) in joints in which the palmar pouch was not discernible (grade 0), and was markedly increased (+37.13 +/- 2.775 mm of Hg) in joints in which the palmar pouch was distended laterally beyond the lateral branch of the suspensory ligament (grade 3). Grade of distention was positively correlated with intra articular pressure (r = 0.758; P < 0.001). Significant compartmentation (P < 0.002) was observed between the dorsal and palmar pouches in all horses. In 25 of the aforementioned horses, (42 joints), which were active or retired Thoroughbred racehorses with variable degree of metacarpophalangeal joint injury/disease, a third needle was inserted into the dorsal pouch, and 0.5-ml increments of saline solution were added every 10 seconds to perform a pressure/volume (elastance) study of the dorsal pouch. The elastance study for each joint ended when leakage into the palmar pouch was detected by the pressure transducer placed in that region. A flexed lateral radio graphic view was taken of each metacarpophalangeal joint in maximal flexion. The maximal angle of flexion was measured from the radiograph, and this angle was subtracted from 180 degrees to acquire the range of motion in flexion. Range of motion in flexion has strong negative correlation (r= -0.68; P < 0.0001) with elastance (stiffness) of the dorsal pouch, and moderate pouches (r= -0.48; P < 0.0001). To adjust for the possible correlations resulting from repeated measures on limbs within horses, a normal linear mixed model was used to assess the effect of limb (right vs left), range of motion in flexion, and volume of saline solution added on the dependent variable (delta mm of Hg) in the elastance study. There was no significant limb effect, but a highly significant effect regarding volume of saline solution added (P < 0.00001) and range of motion in flexion (P < 0.00001). Loss of range of motion in flexion of this joint is associated with shortening or loss of the initial low elastance (flat) phase of the elastance profile. Measuring the elastance of the dorsal pouch or measuring maximal range of motion in flexion provides an objective measure of the degree of metacarpophalangeal joint stiffness secondary to joint disease.

Animals↗

PubMed1993

Assessment of regional myocardial performance with end-systolic pressure length and thickness relationships.

Although end-systolic pressure length and thickness relationships (ESPLR, ESPTR) are now widely used as substitutes for the end-systolic pressure volume relationships, there are some reservations about their use as an index of left ventricular (LV) performance. This study addressed three issues, namely: (1) which loading technique (decreasing preload by inferior vena cava (IVC) balloon occlusion or increasing systolic pressure by aortic constriction) is the most likely to yield usable data; (2) reproducibility of these relationships over a 30 min period; and (3) whether by using end-ejection (zero aortic flow) as a definition of end-systole, ESPLR and ESPTR can be used to characterize myocardial performance independent of load. Thirteen anesthetized beagles, weighing 16-25 kg, were used for this study, and were instrumented with sonomicrometers. We found that when ESPLR and ESPTR were constructed from data derived during aortic constriction, the slopes of these relationships were steeper and more curvilinear than when they were constructed from data recorded during IVC occlusion. In addition, the mean between ESPLR, ESPTR obtained 30 min apart was small, although there was a fair degree of variability between the first and second measurements. Using end-ejection to define end-systole, both ESPLR and ESPTR were relatively insensitive to loading conditions (LV end-diastolic pressure of 8-12 mmHg and 14-18 mmHg, aortic systolic pressure of 7-10 mmHg and 20-25 mmHg above baseline (in terms of the slope and shift (leftward or rightward) in these relationships, but were sensitive to inotropic interventions (dobutamine 2.5 micrograms/kg per min and 5 micrograms/kg per min). We conclude that, ESPLR and ESPTR, defined from measurements at end-ejection, can be used as adequate descriptors of regional myocardial performance if they were constructed from data over a similar pressure range during IVC balloon occlusion.

Animals↗

PubMed1980

The contribution of the left and right sympathetic trunk to control of the diameter of the femoral artery and the consecutive resistant bed.

Laterality of sympathetic control of the diameter of the femoral artery (using an inductive transformer) and the blood flow in its consecutive bed (using a Stattham flowmeter) was studied at the postganglionic level. The fibres leaving LG3, LG4 and LG5 were stimulated. Stimulation of the left sympathetic trunk (ST) evoked 88.33 +/- 0.98% of maximum sympathetic constriction of the ipsilateral and 15.0 +/- 1.1% of the contralateral femoral artery (P less than 0.001). Stimulation of the right ST evoked 86.38 +/- 0.90% of maximum constriction of the ipsilateral and 11.95 +/- 0.99% of the contralateral femoral artery (P less than 0..001). Vasomotor fibres contained in the femoral nerve exert only 23.5 +/- 3.3% (P less than 0.01), while fibres from other sources (probably including the aortic plexus) were responsible for 74.1 +/- 5.2% (P less than 0.001) of maximum constriction. The blood flow in the resistant bed consecutive to the left and right femoral artery is controlled solely by postganglionic fibres of the ipsilateral lumbar ganglia. The results indicate the variability of lateralization of the sympathetic control of the individual segments of the vascular tree.

Animals↗