Ultrasound characterization of acoustic properties of acute intracardiac thrombi: studies in a new experimental model

Echocardiographic differentiation among intracavitary thrombus, cavity noise, and adjacent myocardium can be difficult. As an initial step toward quantitative thrombus characterization with ultrasound, 11 dogs were studied with an in vivo intracardiac thrombus model to delineate the acoustic properties of acute thrombi. The apical coronary arteries were ligated, and subsequently injections of 5% sodium rescinoleate and 1000 units of thrombin at the endocardium-blood interface created left ventricular mural thrombi. Echocardiographic images were obtained in long- and short-axis views with a digital acquisition system, and a statistical analysis of echo intensities was performed in regions of interest in the thrombus, surrounding ventricular cavity and adjacent myocardium. Statistical measurements used to evaluate echo intensities in each region of interest included mean gray level, standard deviation, skewness, and kurtosis. The results showed that thrombus could be distinguished from myocardium (by mean gray level and standard deviation) only in short-axis views, where regions of interest could be placed at similar depths of field. Mean gray level, standard deviation, and skewness all distinguished thrombus from intracavitary blood regardless of the region of interest placement. The phase of the cardiac cycle at which data were acquired did not alter the results. We conclude that acute intracardiac thrombi can be distinguished from surrounding blood and myocardium with ultrasound tissue characterization techniques that may have the potential for clinical application.

A comparison of cholecystokinin-induced changes in gastric emptying and feeding in rats

We have compared the abilities of the cholecystokinin octapeptide (CCK-8) to delay gastric emptying and to influence feeding under similar experimental conditions in the rat. The effect of CCK-8 on gastric emptying was assessed in 6-h-deprived rats receiving 10-ml intragastric test loads of 0.15 M saline or 15% (wt/vol) sucrose. Analysis of half-emptying times indicated that intraperitoneal administration of CCK-8 in doses of 1.4-22.4 micrograms/kg produced a dose-dependent retardation of emptying of both saline and nutrient. Lower doses of CCK-8, 0.01 and 0.1 micrograms/kg, had no effect on gastric emptying. The effect of CCK-8 on feeding was assessed in normally feeding rats tested under the same experimental conditions used in the gastric emptying studies. Doses of CCK-8 capable of retarding gastric emptying also suppressed eating in a dose-dependent manner. These findings provide necessary correlational support for the hypothesis that the satiety produced by CCK-8 may be mediated by inhibition of gastric emptying. However, a further quantitative analysis of the correspondence of the gastric emptying and feeding effects of CCK-8 suggest that retardation of emptying cannot account entirely for the satiety effect of the peptide.

Characterization of receptors for calcitonin gene-related peptide on gastric smooth muscle cells

Rat calcitonin gene-related peptide (rat CGRP) and related peptides did not cause contraction of gastric smooth muscle cells; however, preincubation with rat CGRP or human CGRP inhibited smooth muscle contraction caused by carbachol. Rat CGRP and human CGRP were equipotent in opposing contraction with a half-maximal effect produced by 0.1 nM, but rat calcitonin-adjacent peptide (rat CAP) and human calcitonin had no effect. Rat CGRP caused an increase in cellular adenosine 3',5'-cyclic monophosphate (cAMP) of 60%, which was augmented to 155% with 1 mM isobutyl methylxanthine (IBMX). IBMX did not influence the sensitivity of the muscle cells to rat CGRP to increase cAMP, the half maximal effect being produced by 0.4 nM in the presence or absence of IBMX. Rat CGRP and human CGRP were equipotent for stimulating cAMP, but rat CAP and human calcitonin had no effect. Binding of 125I-CGRP was temperature dependent, saturable, reversible, and specific. Rat CGRP and human CGRP were equipotent at inhibiting binding of 125I-CGRP and rat CAP, and human calcitonin did not inhibit binding. For rat CGRP and human CGRP, the dose-response curves for binding of 125I-CGRP were broad, and both peptides accelerated the rate of dissociation of bound 125I-CGRP. Computer analysis of dose-response curves demonstrated two classes of binding sites for CGRP, one with a high affinity (Kd 3 nM) and another with low affinity (Kd 3,700 nM). Our results indicate that CGRP interacts with previously undescribed receptors on gastric smooth muscle cells to increase cellular cAMP and inhibit contraction.

Small bowel and colonic permeability to 51Cr-EDTA in patients with active inflammatory bowel disease

51Cr-EDTA was administered both orally and per rectum via a catheter to controls and to patients with inflammatory bowel disease. The patients were divided into two groups, either with active inflammation of the small bowel or with active inflammation of the colon. Fifteen patients with Crohn's disease of the small bowel and 19 patients with either Crohn's disease of the colon or ulcerative colitis were investigated. After oral administration of the probe, controls showed a median excretion of 1.17%/24 h of the dose compared to 3.47%/24 h by patients with small bowel disease and 6.07%/24 h by patients with colonic disease. After rectal administration, controls showed a median excretion of 0.74%/24 h of the dose compared to 0.93%/24 h by patients with small bowel disease and 5.73%/24 h by patients with colonic disease. The rectal test differentiated small bowel disease from colonic disease with an accuracy of 85%. The results confirmed the inflamed colon as a site of increased intestinal permeation.

The irritable bowel syndrome

The irritable bowel syndrome (IBS) is an extremely common disorder. It is believed to occur usually after emotional stress and perhaps because of behavioural and dietary factors. There is definite evidence of disturbed gastrointestinal function associated with IBS; however, a diagnostic marker remains elusive. The current trend is to diagnose IBS on the basis of the patient's history and the findings at physical examination and after minimal investigation. The physician-patient relationship remains the most important factor in the management of IBS. Long-term benefit may be achieved with the use of dietary fibre supplements or stool-bulking agents. The evaluation of currently available drugs is difficult because of the placebo effect. Drug therapy should be aimed at specific symptoms and used mainly during the initial phase of treatment.

Videodensitometric analysis of human coronary stenoses: validation in vivo by intraoperative high-frequency epicardial echocardiography

Videodensitometry is a nongeometric method of coronary angiographic analysis that can be used to provide an index of coronary luminal area. However, there are few direct studies in vivo of the relationship of videodensitometric data to independent measures of luminal area in humans. Although videodensitometry is theoretically independent of angiographic projection and luminal shape, validation of these assumptions in vivo is also limited. We therefore used intraoperative high-frequency epicardial echocardiography, a technique that can directly determine human coronary luminal area and shape in vivo, to further validate videodensitometry. A total of 36 arterial segments in the left anterior descending and right coronary arteries were studied by videodensitometry and high-frequency echocardiography. Videodensitometry was performed on angiograms in which the arterial segment of interest was not markedly foreshortened and was uniformly filled with contrast. In 22 discrete lesions (13 with circular lumens and nine with oval or complex lumens), videodensitometric and echocardiographic measures of luminal area correlated well (r = .86). In 33 coronary arterial segments, the effect of angiographic projection on videodensitometry was determined by comparison of the results of videodensitometry performed on left anterior oblique vs right anterior oblique angiograms of the segments. Here too, the correlation was good (r = .94, y = 1.04x + 0.002). The good correlation of left anterior oblique with right anterior oblique videodensitometric results held true for lesions with circular and oval or complex lumens. This study further validates the ability of videodensitometry to provide an index of coronary luminal area and confirms in vivo previous assumptions that the results of videodensitometric analysis are independent of angiographic projection and luminal shape.

Increased responsiveness of jejunal longitudinal muscle in Trichinella-infected rats

We examined in vitro changes in contractility of jejunal longitudinal muscle strips in rats infected with the nematode parasite Trichinella spiralis. Length-passive tension relationships were unchanged. However, muscle from infected rats on days 5 and 6 postinfection (PI) generated maximal active tension induced by carbachol at significantly less stretch (39.9 +/- 1.0 and 34.3 +/- 6.3%, respectively) than control tissues (66.0 +/- 2.3%). In infected rats on day 5 PI, the maximum tension generated by carbachol (1.6 +/- 0.4 g/mm2) and by 5-hydroxytryptamine (5-HTP) (2.6 +/- 0.1 g/mm2) was significantly greater than in control tissue (0.5 +/- 0.2 g/mm2). On removal of calcium from the medium, responses of muscle from control and infected rats were reduced in a proportionate manner. The increased responsiveness to carbachol and 5-HTP was maximal by day 5 PI and was associated with a decrease in the ED50 value for 5-HTP but not for carbachol. All changes were reversed by 23 days PI. These results indicate that T. spiralis infection in the rat is associated with alterations in jejunal longitudinal smooth muscle function.

Clinical potential of ultrasound tissue characterization in cardiomyopathies

Standard methods of echocardiographic analysis permit accurate categorization of cardiomyopathies into dilated, hypertrophic, and restrictive types. However, ascertainment of the cause of a particular cardiomyopathy (e.g., ischemia versus inflammation as the cause of a dilated myopathy) with ultrasound would be greatly facilitated by analysis of myocardial composition with ultrasound tissue characterization techniques. Qualitative observations have identified unusual echocardiographic image texture in hypertrophic cardiomyopathy and in amyloidosis. Quantitative observations have verified these findings and have identified increased ultrasound backscatter in regions of myocardial fibrosis, calcification, and anthracycline-induced cardiomyopathy. Although several technical problems remain unsolved and further research is needed in the mechanisms of normal and abnormal ultrasound/tissue interactions, tissue characterization with ultrasound has the potential to contribute independent information on myocardial composition in patients with cardiomyopathy.

Quantitation in echocardiography

Imaging of the heart is the predominant approach to cardiovascular diagnosis in current practice. Of the wide variety of cardiac imaging techniques available, echocardiography is one of the most widely used. Standard methods of quantitation of M-mode and two-dimensional echocardiograms yield reproducible, accurate measurements of cardiac chamber, wall, and great vessel dimensions. Qualitative analysis of valvular appearance and motion permits the diagnosis of a wide variety of valvular disorders. Doppler echocardiography yields information on blood flow velocity and pattern in the heart and great vessels. Evolving methods of quantitation in echocardiography include computerized image enhancement, computer-assisted border detection, analysis of regional left ventricular contraction, three-dimensional reconstruction, contrast-enhanced echocardiography, ultrasound myocardial tissue characterization, and intraoperative echocardiography. Echocardiography is a dynamic, evolving discipline with the potential of defining cardiac structure, function, blood flow dynamics, myocardial perfusion, and tissue characteristics. Thus, ultrasonography will continue to be of major importance in the diagnosis of cardiac disease.

Reversibility of increased intestinal permeability to 51Cr-EDTA in patients with gastrointestinal inflammatory diseases

Intestinal permeability in adults with inflammatory gastrointestinal diseases was investigated by measuring the 24-h urinary excretion of orally administered 51Cr-EDTA. Eighty controls along with 100 patients with Crohn's disease, 46 patients with ulcerative colitis, 20 patients with gluten-sensitive enteropathy, and 18 patients with other diseases were studied. In controls, the median 24-h excretion was 1.34%/24 h of the oral dose. Patients with Crohn's disease (median 2.96%/24 h), ulcerative colitis (median 2.12%/24 h), and untreated gluten-sensitive enteropathy (median 3.56%/24 h) had significantly elevated urinary excretion of the probe compared to controls (p less than 0.0001). Increased 24-h urinary excretion of 51Cr-EDTA had a high association with intestinal inflammation (p less than 0.0001). Test specificity and sensitivity were 96% and 57%, respectively. A positive test has a 96% probability of correctly diagnosing the presence of intestinal inflammation, whereas a negative test has a 50% probability of predicting the absence of disease.

Patients with irritable bowel syndrome have greater pain tolerance than normal subjects

A low tolerance for pain has been postulated as a factor in the expression of symptoms in patients with irritable bowel syndrome. This has been based on previous work demonstrating reduced intestinal thresholds for rectal pain induced by balloon distention in patients with irritable bowel syndrome. As the disease may alter the rectal response to distention, inferences regarding pain perception and reporting behavior cannot be drawn from these data. In this study, using electrocutaneous stimulation, we found that patients with irritable bowel syndrome had pain reporting behavior comparable to patients with Crohn's disease. Both patient groups were less likely than normals to report a noxious stimulus as painful. This suggests that pain perception and reporting is attenuated in patients with chronic abdominal pain and, accordingly, a generalized reduction in the threshold for reporting pain is not a factor in the expression of symptoms in the irritable bowel syndrome.

Measurement of upper esophageal sphincter pressure. Effect of acute emotional stress

Recent studies suggest that resting upper esophageal sphincter pressure is more labile than previously thought, being augmented during rapid manometric pull-through and markedly decreased during sleep and anesthesia. The effect of acute emotional stress on resting upper esophageal sphincter pressure was evaluated in 13 normal subjects with a manometric sleeve assembly. Manometric sideholes were positioned in the pharynx and cervical and thoracic esophagus while the sleeve sensor straddled the upper esophageal sphincter. Subjects were stressed intermittently by 14-min periods of a dichotic listening task. As incentive, a financial reward was offered and made commensurate with performance. Alterations of heart rate, blood pressure, and skin conductance confirmed the effectiveness of the stressor. The overall mean upper esophageal sphincter pressure during control periods was 46.5 mmHg (SEM = 4.7). During stress there was a significant mean increase (11.8 +/- 2.9 mmHg; p = 0.002) in upper esophageal sphincter pressure from control levels, and the pressure increase during the first 2-min epoch of stress was 20.8 +/- 3.9 mmHg (p = 0.0003). Emotional stress causes significant elevation of upper esophageal pressure in normal subjects. This effect is likely to influence resting sphincter pressure measurements, particularly if measurement conditions are stressful to the subject.

Calcium and contractions of isolated smooth muscle cells from rat myometrium

Smooth muscle cells were isolated from estrogenized rat myometrium by collagenase digestion. Electron microscopic examination and measurement of cell lengths by image-splitting micrometry were carried out after fixation with acrolein. Mean lengths of cells before and after isolation were 81.7 and 66.9 micron, respectively. Responses of cells were compared with contractions of isolated strips recorded isometrically. Effects of carbachol and KCl were examined in 2 mM Ca, 2 mM Ca + 4 mM EGTA, and 2 mM Ca + 10(-8) M nitrendipine solution. Carbachol and KCl produced concentration-dependent shortening of isolated cells maximal at 30 s after addition. The concentrations of carbachol required to produce shortenings were about 100-fold less than those required to produce isometric contractions; but no major difference was observed in the concentration dependence of cell shortening and isometric contraction produced by potassium-induced depolarization. In 2 mM Ca solution, there was a phasic response, followed by a tonic response such that more than 50% of maximum cell shortening was maintained for 10 min. However, in 2 mM Ca + 4 mM EGTA or 10(-8) M nitrendipine, the tonic contraction was abolished and cells rapidly relaxed after 30 s. If carbachol was added to cells after varying times in the EGTA-containing solution, the ability to initiate a contraction declined exponentially with a half-time of 160 s. Effects of depolarization by KCl were examined in 2 mM Ca plus nitrendipine and 2 mM Ca + 4 mM EGTA solution. Shortening occurred in 2 mM Ca solution by depolarization but not if nitrendipine was added. Though shortening was not observed in 2 mM Ca + 4 mM EGTA solution by KCl, subsequent addition of carbachol induced shortening. These results suggested that there was an intracellular Ca store site from which Ca was released by carbachol and which was not affected by depolarization in the absence of external Ca. No evidence was obtained that the contraction persists in Ca2+-free medium in isolated cells, which is in agreement with previous findings in small muscle strips in which only a similar transient response was obtained.

Measurement of right ventricular volume using cine computed tomography

Volume measurements of the right ventricle are clinically important, particularly in the assessment of congenital heart disease. The complex configuration of the right ventricular cavity, however, makes assessment of its volume difficult. Cine computed tomography (CT) permits depiction of cardiac anatomy in parallel, sequential, high-resolution tomographic images. To test whether cine CT would allow accurate, reproducible determination of right ventricular volumes, 11 excised, fixed canine hearts were scanned ex vivo. The endocardial contours of the right ventricular cavity were traced by two independent observers. The right ventricular cavity areas were measured in each image and right ventricular volume calculated by a Simpson's rule approximation. Actual right ventricular volume (range 24-86.5 mL) was measured by cavity fluid capacity. Right ventricular volumes derived from cine CT data correlated closely with actual volumes (R = .96, cine CT volume = 0.99 X [actual volume] + 0.2 mL). Interobserver correlation was excellent (R = .99). It is concluded that cine CT scanning permits accurate, reproducible determination of right ventricular volume ex vivo. This technique should be immediately applicable to the noninvasive evaluation of right ventricular function in children and adults.

Finite element analysis of myocardial diastolic function using three-dimensional echocardiographic reconstructions: application of a new method for study of acute ischemia in dogs

The effect of acute myocardial ischemia on the myocardial elastic modulus has been a matter of controversy. To evaluate this question, diastolic elastic modulus was assessed by finite element analysis of left ventricular geometry using three-dimensional echocardiographic reconstructions and right and left ventricular pressure recordings. Elastic properties were estimated before and after coronary occlusion in 6 open-chest dogs. Elastic modulus values were derived by means of a computer program that determined the global elastic modulus that best predicted the diastolic changes in left ventricular geometry. In the finite element analysis after coronary occlusion, two analyses were performed: one utilizing the control elastic modulus for all segments of the left ventricle and one in which ischemic (dyskinetic) segments were assigned a higher elastic modulus. Results showed that the control elastic modulus was a poor predictor of diastolic left ventricular expansion after coronary occlusion. The finite element analysis in which the ischemic segments were assigned a higher elastic modulus better predicted ischemic diastolic wall motion patterns. Error values (difference between predicted and actual left ventricular segmental diastolic motion) were: control, 1.9 +/- 0.3 mm (mean +/- SD), ischemia, 2.9 +/- 0.5 mm, and 2.2 +/- 0.4 mm using the stiffer elastic modulus for ischemic segments. Error values were significantly higher (p less than 0.05) under ischemic conditions when the control elastic modulus was uniformly applied compared with control and ischemia with dyskinetic segments assigned a higher elastic modulus. From these data, it is concluded that the myocardial diastolic elastic modulus is increased by ischemia and that this approach may allow clinical assessment of intrinsic muscle stiffness.

Computers in cardiac imaging

Imaging has become a widely used technique for the evaluation of cardiac disease. Computer technology and techniques have had an enormous impact on many of the available cardiac imaging methods. These methods include echocardiography, digital angiography, radionuclide imaging, X-ray computed tomography and nuclear magnetic resonance imaging. Computers have performed a number of functions in these cardiac imaging methods, including image acquisition, formation, management, display, enhancement and analysis. This article describes each of these roles that computer technology and techniques currently play in cardiac imaging and concludes with an assessment of the impact that computers have had on the various cardiac imaging methods.

A procedure for within-trial repeated measurement of gastric emptying in the rat

A double sampling procedure, developed originally for investigation of liquid phase gastric emptying in humans, is adapted for use in the rat. The double sampling technique permits repeated measurement of gastric volume, allowing a determination of a time course of emptying in a single experimental session. Further, the method allows determination of the amount of gastric secretion, volume emptied into the intestines, and amount of initial gastric load remaining in the stomach. Experiments are presented which: demonstrate the utility of the technique; validate its accuracy in determining gastric volume; indicate the stability of measurements obtained with this procedure; and indicate a procedure for quantitative evaluation of data obtained with this technique. The limitations of the double sampling method are also discussed.

Altered calcium-handling properties of jejunal smooth muscle from the nematode-infected rat

We examined changes in contractility of jejunal longitudinal muscle from rats infected 8 days previously with the enteric parasite Nippostrongylus brasiliensis. In uninfected control rats, carbachol-induced contraction was maximal at 1 microM carbachol. In muscle from infected rats, there was no change in ED50 for carbachol, but contraction induced by 1 microM carbachol was increased greater than 75% over that in control rats. No significant differences were observed in muscarinic receptor binding characteristics in smooth muscle cells from control and infected rats when [3H]QNB was used as radioligand. Contraction induced by 5-hydroxytryptamine was also substantially greater in muscle from infected rats. In control rats, carbachol-induced contraction was largely independent of extracellular Ca2+, whereas in muscle from infected rats, withdrawing extracellular Ca2+ reduced contraction to below control levels. Furthermore, whereas adding nitrendipine in the presence of extracellular Ca2+ had no effect on carbachol-induced contraction in control rats, it significantly inhibited contraction in muscle from infected rats.

Ultrasound study of acoustic properties of the normal canine heart: comparison of backscatter from all chambers

Much effort has recently been directed toward ultrasound characterization of normal and abnormal left ventricular myocardium. The purpose of this study was to evaluate the normal acoustic properties of all four cardiac chambers as a first step toward tissue characterization of the atria and ventricles. The hypothesis was that integrated ultrasound backscatter would follow the pattern of collagen concentration in the cardiac chambers, being higher in the right side of the heart than in the left and in the atria compared with the ventricles. Seven normal canine hearts, perfusion-fixed in 10% formalin, were examined. Sections of the free walls of right and left ventricles and atria were studied in vitro with a 5 MHz transducer positioned at the focal distance from the epicardium. The radio frequency ultrasound signal energy from each specimen was derived, corrected for sample thickness and expressed as integrated backscatter, in decibel units less than the reflected energy from a stainless steel block. The backscatter was higher from the right ventricle than from the left ventricle (-64.5 +/- 1.25 [mean +/- SEM] [n = 7] versus -73.6 +/- 1.32; p less than 0.05), higher from the right atrium than from the right ventricle (-58.5 +/- 0.83 versus -64.5 +/- 1.25; p less than 0.05) and higher from the left atrium than from the left ventricle (-62.8 +/- 1.14 versus -73.6 +/- 1.32; p less than 0.05). These data show that backscatter is higher in the right ventricle than in the left ventricle and in the atria compared with the ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)

Dissociation of contraction and muscarinic receptor binding to isolated smooth muscle cells

We examined changes in [3H]QNB binding and cell length induced by muscarinic ligands in a suspension of single smooth muscle cells isolated from the canine stomach. Cells contracted following a brief (30 s) exposure to picomolar concentrations of muscarinic agonists and yielded ED50 values of 1.0 +/- 0.7 pM for oxotremorine, 12.5 +/- 1.8 pM for carbachol, and 16.0 +/- 2.9 pM for metacholine. Contraction was inhibited by atropine with a pA2 value of 10.2 +/- 1.1. The binding of [3H]QNB was rapid and reversible and was stereospecific and pharmacologically appropriate. Specific binding of [3H]QNB was saturable and bound with high affinity (KD 1.04 +/- 0.23 nM) to a single class of sites, of which there were approximately 200,000/cell. In competition experiments antagonist binding was generally homogeneous, whereas that of agonists was heterogeneous and subpopulations of binding sites with different affinities for agonists were identified. The Ki value of 8.1 +/- 1.1 nM for inhibition of QNB binding by atropine was greater than the pA2 of 10.2 +/- 1.1 derived from contraction studies. Furthermore, whereas picomolar concentrations of agonists induced cell contraction, substantially higher concentrations (10 nM to 10 mM) were required to inhibit [3H]QNB binding to the isolated cells.

Comparison of methodologies for the measurement of antroduodenal motor activity in the dog

We have compared the abilities of intraluminal strain gauges and manometry to record motor activity from the antrum and duodenum of the anesthetized dog. Responses to intraarterial carbachol, vagal stimulation, and field stimulation recorded by these devices were compared to those registered by strain gauges sewn onto the overlying serosa. In the antrum, the perfused tube (PT) recorded 98% and 97% of field- and vagal-stimulated phasic contractions, respectively, compared with 83% and 90% (p less than 0.005) registered by the intraluminal tube-mounted strain gauges (TSGs). In contrast, in the duodenum there was no difference between the accuracy of these devices in recording phasic activity induced by field stimulation (PT 90% and TSG 87%). Similarly, there was no difference between the abilities of these devices to record tonic contraction induced by carbachol in the antrum (PT 87% and TSG 90%) or duodenum (PT 82% and TSG 87%). However, TSGs misrepresented the configuration of phasic or tonic contractions, producing bifid, negative, or biphasic contractions substantially more frequently than did PT (p less than 0.005). These results illustrate that the accuracy of these two commonly used techniques may be influenced by anatomic factors as well as by the type of contraction recorded.

Muscarinic receptor size on smooth muscle cells and membranes

The loss of [3H]quinuclidinyl benzilate ([3H]QNB) binding following high-energy radiation was used to compare the muscarinic receptor size on single smooth muscle cells isolated by collagenase digestion from the canine stomach and on plasma membranes derived from intact gastric smooth muscle without exposure to exogenous proteolysis. Radiation inactivation of galactose oxidase (68 kdaltons), yeast alcohol dehydrogenase (160 kdaltons), and pyruvate kinase (224 kdaltons) activities were used as molecular-weight standards. Radiation inactivation of [3H]QNB binding to rat brain membranes, which gave a target size of 86 kdaltons, served as an additional control. In isolated smooth muscle cells, the calculated size of the muscarinic receptor was 80 +/- 8 kdaltons. In contrast, in a smooth muscle enriched plasma membrane preparation, muscarinic receptor size was significantly smaller at 45 +/- 3 kdaltons. Larger molecular sizes were obtained either in the presence of protease inhibitors (62 +/- 4 kdaltons) or by using a crude membrane preparation of gastric smooth muscle 86 +/- 7 kdaltons).

Calcium utilization by dispersed canine gastric smooth muscle cells

Smooth muscle cells were isolated by collagenase digestion from the circular layer of the canine gastric corpus, and cell length was measured by image-splitting micrometry. Cells contracted following incubation with KCl, carbachol, and pentagastrin. While contraction induced by 40 mM KCl was inhibited by adding nitrendipine (10 nM) or by removing extracellular calcium and adding EGTA (2 mM), the contraction induced by carbachol (10 pM) was not affected by these measures. Nitrendipine partially inhibited contraction induced by pentagastrin, and pentagastrin also contracted cells that had been depolarized by prior exposure to KCl and nitrendipine. Removing extracellular calcium and adding EGTA partially inhibited contraction induced by maximally (10 pM) or submaximally effective (0.3 pM) concentrations of pentagastrin but did not affect that induced by 300 pM pentagastrin. These results indicate that isolated smooth muscle cells utilize calcium for contraction by three distinct mechanisms. The extent to which each mechanism contributes to contraction depends on the nature of the stimulus and, in the case of pentagastrin, the concentration of the stimulating ligand.

Measurement of left ventricular mass in vivo using gated nuclear magnetic resonance imaging

Alterations of left ventricular mass occur in a variety of congenital and acquired heart diseases. In vivo determination of left ventricular mass, using several different techniques, has been previously reported. Problems inherent in some previous methods include the use of ionizing radiation, complicated geometric assumptions and invasive techniques. We tested the ability of gated nuclear magnetic resonance imaging to determine in vivo left ventricular mass in animals. By studying both dogs (n = 9) and cats (n = 2) of various sizes, a broad range of left ventricular mass (7 to 133 g) was examined. With a 0.5 tesla superconducting nuclear magnetic resonance imaging system the left ventricle was imaged in the transaxial plane and multiple adjacent 10 mm thick slices were obtained. Endocardial and epicardial edges were manually traced in each computer-displayed image. The wall area of each image was determined by computer and the areas were summed and multiplied by the slice thickness and the specific gravity of muscle, providing calculated left ventricular mass. Calculated left ventricular mass was compared with actual postmortem left ventricular mass using linear regression analysis. An excellent relation between calculated and actual mass was found (r = 0.95; SEE = 13.1 g; regression equation: magnetic resonance mass = 0.95 X actual mass + 14.8 g). Intraobserver and interobserver reproducibility were also excellent (r = 0.99). Thus, gated nuclear magnetic resonance imaging can accurately determine in vivo left ventricular mass in anesthetized animals.

Changes in cross-sectional area of the coronary lumen in the six months after angioplasty: a quantitative analysis of the variable response to percutaneous transluminal angioplasty

Although immediate and late changes in coronary stenoses after percutaneous transluminal coronary angioplasty (PTCA) have been reported, most investigators have employed qualitative or semiquantitative techniques to analyze the angiograms. Such data is not optimal because of considerable interobserver variability and the use of relative instead of absolute changes in lesion geometry. Analysis is further compounded by the indistinct edges that characterize coronary lesions immediately after angioplasty. To quantify the changes in minimal cross-sectional area (MCSA) of the coronary lumen that occur during and after PTCA, we analyzed the angiograms of 23 patients before PTCA, immediately after PTCA, and at 7.2 +/- 3.0 (mean +/- SD) months follow-up using two computer-assisted methods of angiographic analysis--quantitative coronary angiography (QCA) and videodensitometry (VID). QCA provides an absolute measure of the area of the lumen; VID is a nongeometric method that is not dependent on exact border recognition. Based on these quantitative methods, we found that successful angioplasty is associated with about a three-fold increase in the MCSA of the lesion (from 1.0 to 3.2 mm2). This area is, however, well below normal and is less than half of the average MCSA of the inflated dilating balloon. Analysis of follow-up angiograms demonstrated that eight of 23 patients had a substantial late increase in the MCSA of the lesion (from 2.7 to 4.1 mm2) after the angioplasty procedure. Clinical, hemodynamic, and angiographic characteristics immediately after PTCA were not predictive of MCSA of the lumen at follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Digital signal and image processing in echocardiography. The American Society of Echocardiography

Digital signal and image processing techniques are acquiring an increasingly important role in the generation and analysis of cardiac images. This is particularly true of 2D echocardiography, in which image acquisition, manipulation, and storage within the echocardiograph, as well as quantitative analysis of echocardiographic data by means of "off-line" systems, depend upon digital techniques. The increasing role of computers in echocardiography makes it essential that echocardiographers and technologists understand the basic principles of digital techniques applied to echocardiographic instrumentation and data analysis. In this article, we have discussed digital techniques as applied to image generation (digital scan conversion, preprocessing, and postprocessing) as well as to the analysis of image data (computer-assisted border detection, 3D reconstruction, tissue characterization, and contrast echocardiography); a general introduction to off-line analysis systems was also given. Experience with other cardiac imaging methods indicates that digital techniques will likely play a dominant role in the future of echocardiographic imaging.

Determination of left ventricular mass in dogs with rapid-acquisition cardiac computed tomographic scanning

The development of left ventricular hypertrophy in patients with heart disease often has far-reaching clinical implications with respect to overall morbidity and mortality. Approaches used to assess left ventricular mass include electrocardiography, echocardiography, contrast ventriculography, single photon-emission tomography, and conventional computed tomography. However, all of these modalities suffer from some major draw back that precludes widespread application to all patients. In this study we assessed the accuracy of determinations of left ventricular mass in 22 dogs by rapid-acquisition (50 msec) computed axial tomography (RACAT), an ultrafast computed tomographic (CT) instrument. Electrocardiographically triggered, end-diastolic, short-axis cardiac scans were obtained from apex to base during administration of intravenous iodinated contrast. Myocardial edges were determined for each tomographic scan by two methods: the regional half-contour method (the CT density half way between that of the left ventricular myocardium and adjacent ventricular cavities or lung) and "interactive plateau thresholding" of the cardiac borders. Left ventricular mass by RACAT was calculated as the sum of the mass of each individual scan from apex to base (modified Simpson's rule). Postmortem left ventricular mass ranged from 58 to 160 g. The correlation between true left ventricular mass and tomographically determined mass was excellent (r = .99), with the slope and y intercept not statistically different from 1 and 0, respectively. The standard error of the estimate was 4.1 g. Interobserver and intraobserver variability for determining left ventricular mass demonstrated excellent agreement (r = .99 and r = .99, respectively). We conclude that quantitative assessment of left ventricular mass can be accurately and reproducibly performed in dogs by rapid acquisition CT scanning. It is likely that this technique will be readily transferable to the clinical settings and prove to be an important method for quantifying left ventricular mass in patients.

Endogenous cholecystokinin and intestinal satiety

The role of endogenous cholecystokinin (CCK) as a mediator of intestinal satiety is examined. We used rats equipped with a chronic gastric fistula and an indwelling duodenal catheter to assess the effects of direct duodenal stimulation on sham feeding. To evaluate the contribution of endogenous CCK to intestinal satiety we used a specific competitive antagonist of the satiety action of CCK, proglumide. Intraduodenal infusion of 11 or 5 ml liquid diet suppressed sham feeding. Administration of proglumide caused a partial reversal of the suppression of feeding produced by the 11-ml, but not the 5-ml, intraduodenal infusion. Administration of proglumide alone did not influence sham feeding but completely abolished the suppression of sham feeding induced by a maximal dose of exogenous CCK. These results indicate that CCK contributes to intestinal satiety under specific test conditions only. Moreover, since that component of suppression reversed by proglumide was small in comparison with the overall inhibition of eating, these results indicate that factors other than CCK are important in intestinal satiety.

Artifactual regional gray level variability in contrast-enhanced two-dimensional echocardiographic images: effect on measurement of the coronary perfusion bed

The purpose of this study was to determine the extent of regional variability of image echocardiographic amplitude (expressed as gray level variability) in contrast-enhanced two-dimensional echocardiographic images, and to assess the effect of such baseline gray level variability on quantitation of the coronary perfusion bed. In 10 anesthetized closed chest dogs, short-axis papillary muscle echocardiographic images were obtained during control preinjection conditions and during injection of three contrast agents into the left main coronary artery with and without circumflex artery occlusion. Regional echocardiographic amplitude variation was measured by computer-based videodensitometric analysis of mean gray levels in four myocardial regions after cavity (background) gray level subtraction. To determine the effect of regional gray level variability on quantitation of the coronary perfusion bed, the contrast-enhanced left anterior descending artery perfusion bed was measured by two methods. The circumferential method ignored myocardial contrast inhomogeneity by measuring the circumferential extent of contrast enhancement, whether or not the enhancement by contrast medium extended transmurally. The exact method measured only the area of myocardium actually enhanced by contrast medium, which often did not extend transmurally. The perfusion beds determined by the two echocardiographic methods were compared with the anatomic perfusion bed determined by postmortem barium-gelatin coronary arteriography. Regional gray levels varied qualitatively and quantitatively in the control state (before contrast injection), with lateral regions being less bright than axial regions. After injection of contrast medium, brightness increased in all regions, the axial regions brightening most.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of oropharyngeal stimulation in cholecystokinin-induced satiety in the sham feeding rat

The belief that oropharyngeal stimulation potentiates the satiety produced by cholecystokinin (CCK) is based on the demonstration that the ability of 20% pure CCK to suppress feeding is enhanced the closer it is injected to a meal. The increase efficacy of CCK with closer temporal proximity to a meal might simply reflect increased peptide levels at the time of feeding. Further, since oropharyngeal synergy has never been demonstrated with pure CCK, studies were performed to evaluate the role of oropharyngeal stimulation in CCK-induced satiety. Rats equipped with gastric fistulae were injected IP with CCK-8 15 min before a test sham feed. In one condition, rats sham fed for 15 min prior to CCK injection; in the other, they did not. CCK-8 suppressed eating in only those cases when its administration was accompanied by oropharyngeal stimulation. Thus, oropharyngeal cues enhance the satiety action of exogenous CCK. A second experiment examined whether oropharyngeal synergy requires oropharyngeal stimulation prior to peptide delivery. CCK-8 was injected into rats coincident with the initation of a test sham feed. Rats had either sham fed, or not sham fed, for 15 min prior to CCK administration. Both conditions produced similar and significant suppressions of eating during the test sham feed. Thus, oropharyngeal cues enhance the action of CCK and oropharyngeal amplification needs only contiguous pairings of oropharyngeal stimulation and feeding.

New directions in cardiac imaging

Cardiac imaging is among the most commonly used diagnostic techniques in cardiovascular medicine. Conventional imaging modes (chest roentgenography, echocardiography, radionuclide imaging, and angiography) allow delineation of cardiac morphology, coronary anatomy, ventricular and valvular function, and cardiac shunts, and permit qualitative evaluation of myocardial perfusion. Four new imaging procedures (digital subtraction angiography, rapid acquisition x-ray computed tomography, emission computed tomography, and magnetic resonance imaging) promise to expand diagnostic capabilities by permitting quantitative analysis of myocardial perfusion, evaluation of myocardial metabolism, and characterization of cardiac tissue composition. These techniques differ widely in cost, availability, and in the additional information they offer. Optimal use will be achieved only through carefully controlled comparative clinical trials directed at specific diagnostic questions.

A secondary prevention, randomized trial of suloctidil in patients with a recent history of thromboembolic stroke

Four hundred and thirty-eight patients who had suffered a thromboembolic stroke not less than two weeks or more than four months previously, were entered into a placebo-controlled randomized clinical trial to determine whether suloctidil (200 mg t.i.d.) would influence the subsequent recurrence of stroke, the occurrence of myocardial infarction, or cardiovascular death. The two treatment groups were comparable at baseline with respect to important prognostic variables and there was good adherence to the study protocol during an average follow-up of 20 months. Significantly more patients complained of side-effects in the suloctidil group and more hepatotoxicity was also reported in the suloctidil group. Four cases of clinical hepatitis were suspected to be due to suloctidil, each of which was reversible on termination of study treatment; relative increases in SGOT and SGPT at three months in the suloctidil group were found to be mild and transient. The primary analysis of efficacy was based on the incidence of the first event of stroke, myocardial infarction or cardiovascular death, but excluding events that occurred more than 28 days after complete withdrawal from study medication for whatever reason. Thus, the primary analysis included 38 events in the suloctidil group and 47 in the placebo group (p = 0.17) representing a risk reduction of 24%. If total mortality is substituted for cardiovascular death, the corresponding figures are 47 in the suloctidil group and 58 in the placebo group (p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of fibrosis in infarcted human hearts by analysis of ultrasonic backscatter

In animal hearts, the magnitude of integrated ultrasonic backscatter is increased in fibrotic myocardium. Our purpose in this study was to quantitate the relationship between ultrasonic backscatter and collagen deposition in 10 excised human hearts with old infarcts. A 2.25 MHz, 50% fractional bandwidth transducer was positioned at the transducer focal distance from the epicardium of each specimen. The radio frequency backscatter signal was digitized, squared, and integrated to yield the integrated ultrasonic backscatter, which was referenced to the backscatter from a water/steel interface. The interrogated myocardium was then excised and divided into two portions. One portion was assayed for hydroxyproline, a marker for collagen. A second portion was sectioned, stained with Masson's trichrome, and studied with the use of a computer-assisted image analysis system. There was a linear correlation between the magnitude of integrated backscatter and myocardial collagen content estimated by hydroxyproline assay (r = .78). Quantitative histologic analysis revealed a variable relationship between the transmural distribution of collagen and the corresponding transmural pattern of the backscatter signal. In two specimens exhibiting a discrete layer of subendocardial fibrosis, the backscatter amplitude was also increased in the subendocardial region. In specimens with other patterns of fibrosis, the local backscatter amplitude did not correspond to the transmural pattern of collagen distribution. We conclude that the quantitative analysis of ultrasonic backscatter shows promise for the noninvasive evaluation of myocardial fibrosis after infarction.

Myocardial infarct size threshold for two-dimensional echocardiographic detection: sensitivity of systolic wall thickening and endocardial motion abnormalities in small versus large infarcts

This study evaluated the ability of 2-dimensional echocardiography to detect myocardial infarcts of varying sizes. Echocardiography was performed in 29 closed-chest, conscious dogs 2 days after circumflex coronary artery occlusion, and the ultrasonic recordings were analyzed for regional abnormalities in either wall thickening or endocardial motion. Acute myocardial infarct (AMI) size and extent were assessed by morphologic examination. In 5 dogs, coronary occlusion failed to produce AMI; in these dogs wall thickening analysis showed no abnormalities (100% specificity), and endocardial motion analysis yielded 1 false-positive result (80% specificity). In 24 dogs an AMI developed; infarcts larger than 18% of left ventricular mass uniformly resulted in echocardiographically detectable contraction abnormalities. When the AMI was small (1 to 6% of left ventricular mass) and primarily subendocardial, the sensitivity of echocardiography was poor: Only 3 of 10 of the dogs with a small AMI had abnormalities by wall thickening, and only 1 of 10 by endocardial motion. Thus, in this canine model of AMI, 2-dimensional echocardiography was insensitive to small, subendocardial AMI. If this is so in humans as well, it is a potential limitation of the clinical use of echocardiography in the detection of AMI.

Quantitative echocardiographic image texture: normal contraction-related variability

Myocardial tissue characterization using ultrasound is a growing area of investigation which attempts to evaluate the structure of the myocardium by analysis of ultrasound signals. Our laboratory has been exploring the use of texture analysis for the determination of myocardial tissue properties from two-dimensional echocardiographic images. In the present study, we tested the hypothesis that echocardiographic image texture varies with cardiac contraction in normal human subjects. In 17 subjects, we obtained long-and short-axis images at end diastole and end systole. Echo image texture was assessed using three classes of quantitative texture measures: run length, gray level difference, and busyness statistics. These statistics measure various attributes of image texture. We found significant contraction-related changes in image texture for the left ventricular posterior wall. This observation is important in that future applications of texture analysis to echocardiographic image data will require that texture be measured at a consistent point in the cardiac cycle. Moreover, it is possible that alteration in the normal variation of texture with cardiac contraction may be a sensitive indicator of abnormal myocardium.

Variation of left ventricular myocardial gray level on two-dimensional echocardiograms as a result of cardiac contraction

Integrated ultrasonic backscatter from normal myocardium has been shown to vary with the phase of cardiac contraction (decreasing from end-diastole to end-systole) in previous studies of open-chest dogs. If confirmed, this finding would have important implications for clinical application of ultrasonic tissue characterization. Our hypothesis was that a cardiac cycle-dependent variation in regional average gray level would be detected on analysis of digitized two-dimensional echocardiograms. We analyzed echocardiographic images from 16 subjects in whom normal, technically good studies were obtained with a commercial phased-array scanner and a 2.25 MHz transducer. Images from six subjects were digitized from stop-frame photographs and those from 10 subjects were obtained directly in digital format from the scanner. Average gray level was measured in a portion of the left ventricular posterior wall in parasternal long-axis images obtained at end-diastole and end-systole by both photographic and digital-image acquisition. In seven of the subjects from whom digital images were acquired, left ventricular posterior wall gray level and ventricular septal gray level were also evaluated on parasternal short-axis images. In images digitized by the photographic technique, mean posterior wall gray level decreased significantly from end-diastole (175 +/- 5.8 SEM) to end-systole (167 +/- 5.1, p less than .05). Similarly, in images digitized directly, mean posterior wall gray level in the long-axis view decreased from end-diastole (71 +/- 3.4) to end-systole (59 +/- 2.5, p less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Rethrombosis after reperfusion with streptokinase: importance of geometry of residual lesions

We tested the hypothesis that lesion rethrombosis after streptokinase reperfusion is related to luminal size of the residual stenosis. Two independent techniques of analyzing coronary angiograms, quantitative coronary angiography and computer-based videodensitometry, were used to estimate the size of the residual lumen immediately after discontinuation of streptokinase. These techniques were selected because they provide independent estimates of cross-sectional area of a lesion with high degrees of reproducibility and minimal observer variability. Twenty-four patients who had undergone successful reperfusion with streptokinase were studied. Seven patients had lesion rethrombosis documented either on a repeat angiogram, at autopsy, or, in one case, by the fact that the patient had an acute transmural infarction resulting in death. Vessel patency was documented by repeat coronary angiography 8 to 14 days after initial streptokinase reperfusion in the other 17 patients. As assessed by quantitative coronary angiography, seven of 13 patients (54%) with minimal luminal cross-sectional areas of less than 0.4 mm2 had rethrombosis. None of the 11 patients with lumens greater than 0.4 mm2 had rethrombosis. In the 17 patients with vessels that remained patent the size of the residual lesion at repeat catheterization was compared with its size immediately after reperfusion with streptokinase. Over the intervening 8 to 14 day interval, an average percentage increase in minimal cross-sectional area of 116 +/- 34% was observed. In seven patients minimal luminal cross-sectional area more than doubled. Integrated optical density, an index of the severity of coronary stenosis derived from computer-based videodensitometry, was also useful in identifying a subgroup of patients at high risk for rethrombosis of lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-assisted edge detection in two-dimensional echocardiography: comparison with anatomic data

Four methods of computer-based edge detection were evaluated for identification of endocardial and epicardial borders on 2-dimensional echocardiograms of excised hearts. A method was also evaluated for observer identification of cardiac borders in the same hearts. The accuracy of computer-derived borders and of observer-derived borders were determined by comparison to anatomic borders measured from photographs of slices of the excised hearts. Echocardiographic borders were compared with anatomic borders by calculation of segmental cavity areas and wall thickness. Each of the methods tested (computer and observer) identified endocardial borders accurately, resulting in cavity segment areas that correlated well with the corresponding anatomic data (r = 0.90 to 0.92). Regional wall thicknesses correlated less well with anatomic data (r = 0.74 to 0.80), suggesting that endocardial borders were identified more accurately than were epicardial borders. Thus, the methods of computer-assisted echocardiographic border detection tested identified the endocardium and epicardium as accurately as a trained observer evaluating unprocessed echocardiograms. Computer-based methods of border detection may be useful in the automated analysis of clinical echocardiograms.

Inhibition of satiety by a cholecystokinin antagonist is independent of gastric emptying

The ability of a cholecystokinin antagonist Proglumide to inhibit satiety induced by intraperitoneal injections of cholecystokinin octapeptide (CCK-OP) and bombesin was examined in rats equipped with chronic gastric cannulae. Both CCK-OP and bombesin significantly suppressed sham feeding. Proglumide administered alone did not alter sham feeding but it abolished the suppression of feeding induced by CCK-OP. In contrast, Proglumide did not inhibit the effect of a low dose of bombesin, but partially inhibited satiety induced by a high dose of bombesin, thus confirming our previous findings. These results indicate that the effect of Proglumide is independent of its recently described effects on gastric emptying in rat.

Ultrasonic backscatter and collagen in normal ventricular myocardium

Integrated ultrasonic backscatter has been related to collagen deposition in fibrotic myocardium. The purpose of our study was to measure the integrated ultrasonic backscatter in the right and left ventricles of 10 normal freshly excised canine hearts and five normal formalin-fixed human hearts. A 2.25 MHz, 50% fractional bandwidth transducer was positioned at the transducer focal distance from the epicardium. The radio frequency backscatter signal, excluding specular reflections, was digitized, squared, and integrated to yield the integrated ultrasonic backscatter (in decibels down from a 100% reflector). The segment of myocardium corresponding to the integrated ultrasonic backscatter sample volume was excised and assayed for hydroxyproline, a marker for collagen. A second purpose of our study was to evaluate the influence of fixation with formalin on the backscatter. Regional integrated ultrasonic backscatter was therefore measured in 10 freshly excised canine left ventricles, which were fixed in 10% formalin for 2 weeks. Integrated ultrasonic backscatter measurements were then repeated. In freshly excised canine hearts, the integrated ultrasonic backscatter from right ventricle was higher than that from left ventricle (-60.4 +/- 1.6 [SEM] vs -66.9 +/- 1.0 dB; p less than .001). The collagen content of right ventricle was also higher than that of left ventricle (4.40 +/- 0.26 [SEM] vs 3.58 +/- 0.13 micrograms/mg dry weight; p less than .005). Similar results were obtained in human hearts. There were no correlations between integrated ultrasonic backscatter and collagen content (r = .28 and .32 for dogs and humans, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-assisted quantitation of myocardial fibrosis in histologic sections

Histologic characterization of the myocardium may require estimation of the collagen content of the specimen. A computer-assisted method can be used to determine collagen content from histologic sections. Full-thickness segments of normal or fibrotic left ventricular myocardium from ten human hearts were divided into portions for hydroxyproline assay and for trichrome staining of histologic sections. The sections were digitized using a computerized video analysis system and were segmented into collagen and muscle regions using a gray-level threshold technique that yielded an estimate of the percent of collagen. A wide range of collagen content, from normal (5 micrograms of hydroxyproline per milligram of dry weight) to fibrotic (38 micrograms/mg) myocardium, was studied. The percentage of collagen from analysis of histologic sections strongly correlated with the hydroxyproline level, with excellent intraobserver and interobserver concordance. Results were unaffected by variations in histochemical staining.

Relations between 2-dimensional echocardiographic wall thickening abnormalities, myocardial infarct size and coronary risk area in normal and hypertrophied myocardium in dogs

Systolic wall thickening abnormalities are sensitive indicators of ischemia and infarction. One purpose of this investigation was to assess the relation between coronary risk area, infarct size and wall thickening abnormalities (dyskinesia) using 2-dimensional echocardiography (2-D echo) in a closed-chest conscious dog model of acute myocardial infarction. The second purpose was to study the effects of systemic hypertension (SH) and left ventricular (LV) hypertrophy on these relations. Our hypothesis was that the infarct size and the extent of 2D echocardiographic dyskinesia would be quantitatively different in SH-LV hypertrophy, a condition in which coronary vascular reserve is diminished. Permanent circumflex coronary occlusion was performed in 15 conscious normal dogs and in 14 dogs with LV hypertrophy secondary to renal hypertension. Two-dimensional echocardiograms were obtained before, 20 minutes after and 2 days after coronary occlusion. The systolic wall thickening along 12 equidistant radii was analyzed in short-axis images. Percent dyskinesia on 2-D echo was defined as the percentage of radii showing systolic thinning. Infarct size was determined pathologically and risk area was determined angiographically. For a given risk area, coronary occlusion resulted in a larger infarction in dogs with SH-LV hypertrophy than in normal dogs (p less than 0.05). Two-dimensional echocardiographic dyskinesia correlated well with infarct size both at 20 minutes (r = 0.92) and 2 days (r = 0.94); dyskinesia modestly overestimated the infarct size and underestimated the risk area. The relations were similar in both normal and SH-LV hypertrophy groups.(ABSTRACT TRUNCATED AT 250 WORDS)