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PubMed2001

Regional expression of endothelin-1, ANP, IGF-1, and LV wall stress in the infarcted rat heart.

We hypothesized that myocardial infarction induces regional and temporal differences in endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and insulin-like growth factor-1 (IGF-1) gene expression that correlate with left ventricular (LV) wall stress. Echocardiography and LV pressure measurements were performed in coronary artery-ligated or sham-operated rats. Gene expression was measured by competitive RT-PCR in the infarct, border zone, and remote area and in regionally isolated cardiomyocytes. ET-1 and IGF-1 expression was highest in the infarcted myocardium, whereas ANP expression was highest in noninfarcted myocardium. For all genes, remote area expression was highest after 7 days. At 42 days, ANP maintained maximum expression, ET-1 decreased to 50% of peak levels, and IGF-1 was normalized. Cardiomyocyte expression followed the same pattern as in the myocardium except for a markedly lower IGF-1 expression. Diastolic wall stress was the best hemodynamic variable to predict ET-1 and ANP expression in the remote area. We conclude that ET-1, ANP, and IGF-1 are expressed in different patterns in the infarcted heart in relation to time, functional regions, cellular distribution, and mechanical load.

Animals↗

PubMed1985

Validation in dogs of a rapid digital angiographic technique to measure relative coronary blood flow during routine cardiac catheterization.

Assessment of the functional significance of anatomically defined coronary stenoses has been hampered by the lack of clinically applicable techniques of measuring coronary blood flow or flow ratios. A digital angiographic technique is reported that allows rapid analysis of relative regional coronary blood flow during routine cardiac catheterization. This technique was validated in dogs by comparing digital flow ratio estimates with electromagnetic-flow (EMF) ratio measurements. Fourteen open-chest dogs had EMF probes placed on the proximal left anterior descending artery before selective coronary angiography. Electrocardiographically gated images were acquired directly by a digital radiographic system during both baseline blood flow and either contrast or papaverine-induced hyperemia. Dual-parameter functional images were generated using color and intensity coding to represent contrast arrival time and contrast density, respectively. For analysis, myocardial areas of interest were created over the distal perfusion bed of the left anterior descending coronary artery. Mean contrast density/appearance time (CD/AT) values were computer calculated as the mean density divided by the mean arrival time for each. Coronary flow reserve was determined as the ratio of the CD/AT value for a hyperemic image divided by the CD/AT value for the corresponding baseline image. CD/AT ratios correlated well (r = 0.92) with actual EMF ratios (CD/AT Ratio = 0.90 EMF Ratio +0.12, n = 48 ratios). Reproducibility was +/- 13%. Interobserver (r = 0.99) and intraobserver (r = 0.98) variability was excellent. Thus, rapid, accurate and reproducible estimates of relative regional coronary blood flow are possible using digital radiography.

Animals↗

PubMed1994

Assessment of left ventricular dysfunction by nuclear cardiology.

Nuclear cardiology techniques may be of help in evaluating the patient with symptoms of congestive heart failure and ventricular dysfunction in two respects: quantification of functional parameters by radionuclide angiography, and differentiation of viable from nonviable myocardium by perfusion and metabolic imaging. Left ventricular ejection fraction and volumes can be accurately assessed by equilibrium radionuclide angiography with a count-based method without any geometric assumptions. Indeed, because of its high reproducibility, this method is particularly suited for making sequential measurements in the same patient. The distinction between viable or reversible and scarred or irreversible dysfunctional myocardium can be made on the basis of myocardial perfusion, cell membrane integrity, and metabolic activity. Thallium myocardial imaging is used clinically to assess the first two parameters based on experimental data. Two clinical methods may be applied to the detection of viability: stress-redistribution-reinjection imaging or rest-redistribution imaging. In both of these, the severity of the reduction in thallium activity should be assessed to discriminate viable from nonviable myocardium. Stress-redistribution-reinjection thallium imaging should be the first approach, if possible, because inducible ischemia is a much more significant clinical variable in a patient with ventricular dysfunction in terms of management and risk assessment than is knowledge of myocardial viability. Positron emission tomography (PET) provides enhanced image resolution and correction for body attenuation, thereby overcoming the two major limitations of thallium imaging. In addition, it provides the capacity to quantitate regional blood flow and to assess regional metabolic activity independent of flow. Overall, the accuracies of thallium imaging (around 70%) and PET imaging (around 82%) are similar for the prediction of segmental changes after revascularization. However, in patients with poor global left ventricular function, the accuracy of PET seems to be better. Further studies are needed in a large number of patients evaluated for regional and global function to establish algorithms using thallium and PET imaging in dysfunctional myocardium. Dobutamine echocardiography should also be evaluated in these algorithms.

Cardiology↗

PubMed2005

Intraindividual variability of striatal (1)H-MRS brain metabolite measurements at 3 T.

PURPOSE: To measure possible positional and diurnal physiological effects on brain metabolites in single-voxel proton magnetic resonance spectroscopy ((1)H-MRS) measurements of the right and left striatum. METHODS: (1)H-MRS measurements were performed in 10 healthy adult volunteers using a short echo PRESS sequence (TE=30 ms, TR=3000 ms). Each individual was scanned during both morning and afternoon hours. Regions of interest were right and left striatum. To control for systematic drift in scanner performance, (1)H-MRS measurements of a standard phantom solution were also acquired. Statistical analysis was performed using a repeated measures analysis of variance that included three within-subject factors: metabolite (N-acetyl-aspartate [NAA] or creatine [Cr]), laterality (left or right caudate) and time (morning or afternoon). RESULTS: A significant interaction (P<.016) between time of day and metabolite levels was observed. Further exploration of this finding revealed a significant difference between morning and afternoon levels of NAA (P<.044) but not Cr. In addition, no significant morning-to-afternoon differences were observed for the (1)H-MRS phantom measurements. CONCLUSIONS: Systematic variation due to scanner performance does not account for the changes observed in repeated measurements of striatal NAA levels. This difference may be accounted for by either repositioning effects or circadian physiological effects. Further studies are required to learn whether time of day standardization of (1)H-MRS acquisitions may contribute to improved reproducibility of measurements.

Analysis of Variance↗

PubMed1998

Abnormal Inflow Wave Propagation in Patients with Doppler Characteristics of Impaired Left Ventricular Relaxation: Assessment by a Novel Method Through Application of the Range Ambiguity.

With application of the range ambiguity, a delay between the flow onset at both the mitral valve and the apex has been shown to be present in patients with a severely dilated and poorly contracting left ventricle and those with acute myocardial infarction with abnormal apical wall motion, but the delay has been absent in normal subjects. Nevertheless, whether there is a delay between the flow onset at both regions in the presence of impaired left ventricular relaxation remains unknown. This study was undertaken to evaluate the left ventricular inflow wave propagation in control subjects and patients with impaired left ventricular relaxation. Eighteen patients with normal systolic function and Doppler characteristics of impaired relaxation of the left ventricle and 17 age- and sex-matched healthy control subjects were included. Range ambiguity was used to simultaneously record the phantom Doppler signals from the mitral valve region and the true ones from the apex. The inflow wave propagation velocity was derived from the inflow wave propagation distance divided by the time between the mitral valve and the apex. There was always some delay between the flow onset at both the mitral valve and the apex in both the controls and the patients (47 +/- 13 msec vs 85 +/- 19 msec, P < 0.001). The inflow wave propagation velocity was 160 +/- 50 cm/sec and 90 +/- 20 cm/sec in the control subjects and the patients, respectively (P < 0.001). Multiple linear regression analyses of the significantly correlated variables stepwisely selected the deceleration time of the E wave (R(2) = 0.53, P < 0.001) and age (R(2) = 0.06, P = 0.039) as the significant determinants of the left ventricular inflow wave propagation velocity. In conclusion, the application of the range ambiguity offers a new method of determining the left ventricular inflow wave propagation velocity, and Doppler characteristics of impaired left ventricular relaxation are associated with a slower inflow wave propagation from the mitral valve to the apex.

Journal Article↗

PubMed1990

An accurate, nontraumatic ultrasonic method to monitor myocardial wall thickening in patients undergoing cardiac surgery.

Measurement of systolic wall thickening by sonomicrometry provides an accurate index of regional left ventricular function, but the trauma of crystal insertion limits its widespread clinical use. The first clinical application of a 10 MHz ultrasonic Doppler probe that can be either sutured or applied by suction to the epicardium and can measure wall thickening at any depth of the left ventricular wall is described. In 18 dogs, measurements obtained with the suction probe correlated well (r = 0.97) with those of a previously validated sutured probe. To assess clinical feasibility, the probe was applied to the epicardium of patients undergoing coronary bypass surgery. Good quality wall thickening signals were obtained with no complications. Transmural left ventricular thickening fraction before bypass surgery was 34 +/- 3% (mean value +/- SE) at the mid-ventricular lateral wall, 33 +/- 4% at the anterior basal wall and 26 +/- 4% at the mid-ventricular posterior wall. Right ventricular thickening fraction averaged 25 +/- 3%. Endocardial thickening fraction tended to exceed epicardial thickening fraction, although the difference attained statistical significance (p less than 0.05) only at the anterior basal wall. On average, thickening fraction during the immediate postoperative period remained unchanged compared with the preoperative values, but a marked individual variability was observed, with 7 of 15 patients exhibiting a decrease and 8 an increase. Exteriorization of the wires attached to the sutured probe allowed continuous in situ monitoring of wall thickening in the postoperative period and subsequent removal of the probe. In six patients the crystal was left in place for 48 to 72 h after surgery and then removed without complications; good wall thickening signals were obtained for the entire period during which the probe was implanted. Thus, the Doppler probe is an accurate, atraumatic method for measuring right and left ventricular regional function. Transmural, endocardial and epicardial function can be mapped at various sites during surgery, and post-operatively one can monitor serial changes of regional function and assess the effects of cardioplegia and other therapeutic interventions. This technique should be useful for both investigative and clinical purposes.

Adult↗

PubMed1995

A new, simple and accurate method for determining ejection fraction by Doppler echocardiography.

OBJECTIVE: To evaluate the feasibility, accuracy and reproducibility of a new and simple method for determining ejection fraction by Doppler echocardiography. This method should theoretically be less influenced by the distortions of left ventricular geometry caused by prior myocardial infarction. DESIGN: Two groups of patients (total 114) were evaluated independently at the Quebec and Ottawa Heart Institutes (60 and 54 patients, respectively). All were referred for radionuclide angiography performed within 24 h of the echocardiogram. Regional asynergy was present in 59% of Quebec patients and 37% of Ottawa patients. The new method for calculating ejection fraction consisted of dividing Doppler derived stroke volume in the left ventricular outflow tract by left ventricular end-diastolic volume calculated by Teichholz's formula; for comparison, ejection fraction was also measured by single plane area length or multiple disc planimetry as well as by the Quinones method at the Quebec Heart Institute. RESULTS: Feasibility of the new method was 97% in Quebec and 100% in Ottawa. Compared with radionuclide angiography, the correlation coefficient for the new method was 0.92 (standard error of estimate [SEE] = 7.3) in Quebec compared with 0.88 (SEE = 8.5 and 8.1) for both the Quinones and single plane area length methods, and 0.84 (SEE = 12.0) in Ottawa compared with 0.77 (SEE = 10.9) for the single plane multiple disc method. Correlations in patients with regional asynergy were 0.90 in Quebec and 0.75 in Ottawa compared with 0.81 and 0.54 with planimetry. Correlation coefficients for interobserver variability in 12 patients were 0.97 with the new method compared with 0.83 with the Quinones method and 0.85 with single plane planimetry. CONCLUSION: This new and simple method is feasible, accurate and reproducible even in patients with regional asynergy. Provided there is no significant mitral regurgitation, it is a time-saving alternative for the routine evaluation of ejection fraction by Doppler echocardiography.

Angiocardiography↗

PubMedDate not supplied

Temporal profile of connexin 43 mRNA expression in a tetanus toxin-induced seizure disorder.

The messenger ribonucleic acid (mRNA) of gap junction protein connexin 43 was quantified in the tetanus toxin rat model of focal epilepsy following injection of toxin into the left amygdala. Animals were monitored electrographically at weekly intervals with bilateral amygdala electrodes. Cohorts of 3 rats were sacrificed at weeks 1, 2, 3, 4, 6, 8, and 10, and bilateral regions containing the amygdala and posterior cerebral cortex were sampled, frozen, and later pooled for northern blot analysis. Spike generation was manifest in all animals during the first 4 wk followed by variable attenuation and cessation by 10 wk. Electrode implantation alone was shown by regression analysis to cause significant (p < 0.05) elevation of connexin mRNA in weeks 1-4. Injection of toxin diminished connexin mRNA expression in the amygdala when compared to electrode implantation alone. No trend in connexin mRNA expression was established over time in either amygdala or cerebral cortex in the acute epileptic or chronic postepileptic phase. No association between connexin 43 mRNA expression and the development of epileptogenicity was found in the context of a self-limiting animal model of focal epilepsy.

Amygdala↗

PubMed1988

Sectional and segmental variability of left ventricular function: experimental and clinical studies using ultrafast computed tomography.

In this study, ultrafast computed tomography, a new high spatial and temporal resolution imaging system, was employed to define the range of sectional (tomographic) and segmental left ventricular function in 11 normal anesthetized dogs and 11 normal human volunteers. After intravenous infusion of contrast agent, multilevel tomographic images of the left ventricle (apex to base) were acquired at a rate of 17 frames/s. Analysis of these studies demonstrated substantial but predictable heterogeneity in left ventricular contraction from apex to base. In dogs and humans, for example, the average tomographic ejection fraction of the most basal level of the left ventricle was 40% less than that of the most apical level (p less than 0.05). In humans, circumferential segmental cavity contraction at the mid-papillary muscle level was relatively homogeneous (range 50 to 92% for 12 wedge-shaped segments around the tomographic circumference) if the reference system employed an endocardial centroid, but was less uniform if it used an epicardial centroid (range 22 to 98%). It is concluded that contraction of the normal left ventricle in dogs and humans is heterogeneous both between levels (apex to base) and within a single level (circumferential cavity contraction). However, the patterns of cavity contraction from apex to base and circumferential segmental cavity contraction within a given level as defined by ultrafast computed tomography are sufficiently narrow and predictable in normal individuals that these variables may be useful to define regional contraction abnormalities in pathologic conditions.

Adult↗

PubMed1994

Regional nonischemic performance as assessed by end-systolic measures of shortening and thickening.

OBJECTIVES: Nonischemic contractile segmental performance was characterized by the end-systolic pressure-length and pressure-thickness relations during regional ischemia induced by proximal left anterior descending and left circumflex coronary artery occlusions. BACKGROUND: The increases in shortening and thickening of the nonischemic myocardium during acute ischemia have been attributed to alterations in the regional loading conditions. However, it is uncertain to what extent ischemia affects the contractile performance of the nonischemic zone. METHODS: Twenty-seven beagle dogs were instrumented with sonomicrometers and micromanometer pressure gauges. End-systolic pressure-length and pressure-thickness relation data were obtained during vena cava balloon inflation. Control data were obtained in both left anterior descending and left circumflex regions. Then, in random order, either the left anterior descending or left circumflex coronary artery was occluded for 90 s, and hemodynamic and nonischemic end-systolic pressure-length and pressure-thickness data were obtained. After a 45-min recovery period, the other artery was occluded, and the same recordings were obtained. RESULTS: The end-systolic pressure-length relation exhibited variable degrees of rightward and downward shifts and the end-systolic pressure-thickness relation variable degrees of leftward and downward shifts. Left circumflex coronary artery occlusion was associated with a greater downward displacement (decreased slope) of the nonischemic end-systolic pressure-length relation than left anterior descending coronary artery occlusion. The baseline slope was the best predictor of the change in slope of the end-systolic pressure-length and pressure-thickness relations. The left circumflex coronary artery supplied a larger proportion of left ventricular myocardial mass than the left anterior descending coronary artery. CONCLUSION: Acute ischemia profoundly affects the end-systolic performance of the nonischemic segment. Furthermore, the site, and probably size, of the ischemic zone may be important determinants of nonischemic contractile performance.

Animals↗

PubMed2004

An MRI study of spatial probability brain map differences between first-episode schizophrenia and normal controls.

We created a spatial probability atlas of schizophrenia to provide information about the neuroanatomic variability of brain regions of patients with the disorder. Probability maps of 16 regions of interest (ROIs) were constructed by taking manually parcellated ROIs from subjects' magnetic resonance images (MRIs) and linearly transforming them into Talairach space using the Montreal Neurological Institute (MNI) template. ROIs included temporal, parietal, and prefrontal cortex subregions, with a principal focus on temporal lobe structures. Subject Ns ranged from 11 to 28 for the different ROIs. Our global measure of the spatial distribution of the transformed ROI was the sum of voxels with 50% overlap among subjects. The superior temporal gyrus (STG) and fusiform gyrus (FG) had lower values for schizophrenic subjects than for normal controls, suggestive of greater spatial variability for these ROIs in schizophrenic subjects. For the computation of statistical significance of group differences in portions of the ROI, we used voxel-wise comparisons and Fisher's exact test. First-episode schizophrenic patients compared with controls showed lower probability (P < 0.05) at dorso-posterior areas of planum temporale and Heschl's gyrus, lateral and anterior regions in the left hippocampus (HIPP), and dorsolateral regions of fusiform gyrus. Importantly, most ROIs of schizophrenic subjects showed a significantly lower spatial overlap than controls, even after nonlinear spatial normalization, suggesting a greater heterogeneity in the spatial distribution of ROIs. There is consequently a need for caution in neuroimaging studies where data from schizophrenic subjects are normalized to a particular stereotaxic coordinate system based on healthy controls. Apparent group differences in activation may simply reflect a greater heterogeneity of spatial distribution in schizophrenia.

Adult↗

PubMed1987

Silent ischemia during coronary occlusion produced by balloon inflation: relation to regional myocardial dysfunction.

Thirty patients with stable exertional angina undergoing percutaneous transluminal coronary angioplasty of an isolated obstructive lesion of the proximal left anterior descending artery were prospectively evaluated to investigate the relation between angina induced by balloon inflation and the quantity and severity of myocardial ischemia as determined by electrocardiographic (ECG) monitoring and by echocardiographic assessment of regional and global left ventricular wall motion. Anginal pain interviews, continuous two-dimensional echocardiographic recordings and 12 lead ECG recordings at 10 second intervals were obtained for the first two inflation sequences. Seventeen patients had angina with both inflations (symptomatic group), seven patients had no angina or related symptoms during either inflation (asymptomatic group) and six patients had both painful and painless inflations (mixed response group). Comparison of the three groups revealed that they did not differ in mean age, sex distribution, prior history of angina or the incidence of comorbid conditions. Echocardiographic measurements of global and regional left ventricular dysfunction during balloon inflation were comparable in the symptomatic and asymptomatic groups. Similarly, there were no significant differences in the time to onset or magnitude of ST segment changes. The results of the wall motion and ECG studies in the mixed response group paralleled the results in the symptomatic and asymptomatic groups, with no significant differences in any of the variables measured between the painful and painless inflations. These data demonstrate that silent myocardial ischemia occurs in an appreciable proportion of patients during coronary angioplasty and the absence of angina does not imply that a lesser amount of myocardium is jeopardized than with painful inflations.

Angina Pectoris↗

PubMed1999

Kriging with nonparametric variance function estimation.

A method for fitting regression models to data that exhibit spatial correlation and heteroskedasticity is proposed. It is well known that ignoring a nonconstant variance does not bias least-squares estimates of regression parameters; thus, data analysts are easily lead to the false belief that moderate heteroskedasticity can generally be ignored. Unfortunately, ignoring nonconstant variance when fitting variograms can seriously bias estimated correlation functions. By modeling heteroskedasticity and standardizing by estimated standard deviations, our approach eliminates this bias in the correlations. A combination of parametric and nonparametric regression techniques is used to iteratively estimate the various components of the model. The approach is demonstrated on a large data set of predicted nitrogen runoff from agricultural lands in the Midwest and Northern Plains regions of the U.S.A. For this data set, the model comprises three main components: (1) the mean function, which includes farming practice variables, local soil and climate characteristics, and the nitrogen application treatment, is assumed to be linear in the parameters and is fitted by generalized least squares; (2) the variance function, which contains a local and a spatial component whose shapes are left unspecified, is estimated by local linear regression; and (3) the spatial correlation function is estimated by fitting a parametric variogram model to the standardized residuals, with the standardization adjusting the variogram for the presence of heteroskedasticity. The fitting of these three components is iterated until convergence. The model provides an improved fit to the data compared with a previous model that ignored the heteroskedasticity and the spatial correlation.

Agriculture↗

PubMed2004

Two cases of multiple eccrine spiradenoma with linear or localized formation.

We report two rare cases of recurrent, multiple eccrine spiradenoma. Both cases presented with extensive lesions comprised of multiple red papules of various sizes and a soft blue-red nodule. The first case was a 30-year-old woman. Her lesions followed a linear arrangement on her chin, and extended down the right side of the neck with spontaneous pain. The second case was a 57-year-old woman with tumors in a localized group on the left occipital region without pain. A search of the literature revealed only 15 reported cases of linear/zosteriform/nevoid multiple eccrine spiradenoma. Both cases were treated by surgical excision. Most of the red papules displayed typical histological features including two cell types: large clear cells with low-density cytoplasm; and small dark cells with high-density cytoplasm. The large soft tumors exhibited a variable histological appearance. In the first case, the cystic tumors displayed an homogeneous structure comprised of eosinophilic material. In the second case, the cystic tumors included abundant interstitial tissue.

Adenoma, Sweat Gland↗

PubMed1994

AL kappa amyloid in a solitary extradural lymphoma.

A 68 year old man with a 10 year history of apparently benign IgM kappa paraproteinaemia presented with dysarthria, left hemiparesis, and a sensory peripheral neuropathy. A calcified right temporoparietal extradural mass was shown by scintigraphy with 123I-serum amyloid P component to contain amyloid. There were no extracranial amyloid deposits. Clinical improvement followed craniotomy and partial resection of tissue which consisted of amyloid and a mixed mononuclear cell infiltrate. The amyloid fibrils consisted of the framework 1 region of the variable domain of monoclonal kappa IV immunoglobulin light chains. There was a prominent B-cell clonal immunoglobulin gene rearrangement in the tumour tissue, supporting a diagnosis of lymphoplasmacytic lymphoma, but no sign of systemic lymphoma. Neurological state, tumour volume, and quantity of amyloid have remained static for two years after treatment with chlorambucil.

Aged↗

PubMed2006

Complete predicted three-dimensional structure of the facilitator transmembrane protein and hepatitis C virus receptor CD81: conserved and variable structural domains in the tetraspanin superfamily.

Tetraspanins are a superfamily of transmembrane proteins implicated in cellular development, motility, and activation through their interactions with a large range of proteins and with specific membrane microdomains. The complete three-dimensional structure of the tetraspanin CD81 has been predicted by molecular modeling and from the crystallographic structure of the EC2 large extracellular domain. Periodicity of sequence conservation, homology modeling, secondary structure prediction, and protein docking were used. The transmembrane domain appears organized as a four-stranded left-handed coiled coil directly connecting to two helices of the EC2. A smaller extracellular loop EC1 contains a small largely hydrophobic beta-strand that packs in a conserved hydrophobic groove of the EC2. The palmitoylable intracellular N-terminal segment forms an amphipathic membrane-parallel helix. Structural variability occurs mainly in an hypervariable subdomain of the EC2 and in intracellular regions. Therefore, the variable interaction selectivity of tetraspanins originates both from sequence variability within structurally conserved domains and from the occurrence of small structurally variable domains. In CD81 and other tetraspanins, the numerous membrane-exposed aromatic residues are asymmetrically clustered and protrude on one side of the transmembrane domain. This may represent a functional specialization of these two sides for interactions with cholesterol, proteins, or membrane microdomains.

Algorithms↗

PubMed2001

Regional asynchrony during acute myocardial ischemia quantified by ultrasound strain rate imaging.

OBJECTIVES: We propose a new method to easily quantify asynchronous wall motion due to postsystolic shortening (PSS). We also studied the relationship of the spatial and temporal extent of PSS to the extent of myocardium at ischemic risk after variable duration of ischemia. BACKGROUND: Postsystolic shortening is a sensitive marker of asynchrony during ischemia. Current techniques for detection of asynchrony are either subjective, or invasive and time-consuming. Strain rate imaging (SRI) can noninvasively depict PSS as prolonged compression/expansion crossover. METHODS: Nineteen open-chest pigs were scanned from apical views, before and after left anterior descending coronary artery occlusion. Strain rates were derived offline from tissue Doppler velocity cineloops. The time from electrocardiographic R-wave to the occurrence of compression/expansion crossover (TCEC) was calculated. Prolonged TCEC during ischemia was identified using a standardized analysis and both spatial (% of left ventricle) and temporal extent were quantified. The extent of myocardium at risk was measured in seven animals from dye-stained specimens. RESULTS: Prolonged TCEC was found in all ischemic segments. There was a good correlation (r = 0.91; p < 0.001) and good agreement between the spatial distributions of prolonged TCEC and myocardium at risk. The extent of myocardium at risk was better approximated by TCEC measurement (36 +/- 7% vs. 39 +/- 8%, respectively; p = NS) than by wall motion analysis (47 +/- 17%, p < 0.05). The duration of occlusion did not prolong TCEC. CONCLUSIONS: Prolonged TCEC consistently occurs in ischemic myocardium and is apparently not affected by the duration of ischemia. Standardized analysis of TCEC in SRI closely quantifies the extent of ischemic myocardium. This new method may be a useful tool in other cardiac conditions associated with regional diastolic asynchrony.

Animals↗

PubMedDate not supplied

Combined assessment of left ventricular function and rest-redistribution regional myocardial thallium-201 activity for prognostic evaluation of patients with chronic coronary artery disease and left ventricular dysfunction.

BACKGROUND: This study evaluated the prognostic value of combined assessment of left ventricular (LV) function and regional myocardial thallium activity in patients with nonrecent myocardial infarction and LV dysfunction. METHODS AND RESULTS: Eighty-two patients with previous myocardial infarction (>8 weeks) and echocardiographic evidence of LV dysfunction underwent thallium-201 rest-redistribution tomography and cardiac catheterization. During the follow-up period (mean 25 months) there were 18 cardiac events (14 deaths and 4 nonfatal myocardial infarctions). Multivariate Cox regression analysis on clinical, angiographic, and thallium variables showed that the number of echocardiographic dysfunctional segments with preserved thallium uptake (> or =50% of peak activity; chi-square 11.03; p<0.005) and age (chi-square 8.12, p<0.01) were predictive of poor outcome. At incremental analysis, combined echocardiographic and thallium data provided significant additional information to clinical, thallium, and LV functional data, increasing global chi-square value from 22.4 to 31.5 (p< 0.01). Similarly, combined data gave additional information after considering clinical, echocardiographic, and LV functional data, increasing global chi-square from 17.8 to 22.3 (p <0.05). Differently, the number of diseased vessels at coronary angiography did not add further prognostic information. CONCLUSIONS: In patients with previous myocardial infarction and chronic LV dysfunction, the combination of echocardiographic and thallium rest-redistribution imaging data gives prognostic information incremental to those of clinical and LV functional data and to those of each technique considered separately.

Cardiac Catheterization↗