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Biomedical subjects

S Meerbaum

Publications and source records attributed to S Meerbaum.

At least 37 records · Page 2Linked to original sources
PubMed1985

Synchronized coronary venous retroperfusion: prompt improvement of left ventricular function in experimental myocardial ischemia.

The effect of synchronized coronary venous retroperfusion of arterial blood on cardiac function after experimental coronary occlusion was examined by two-dimensional echocardiography. In 18 closed chest anesthetized dogs, the proximal left anterior descending coronary artery was occluded for 6 hours with an intracoronary balloon catheter. Eight of these animals served as untreated controls. Ten were treated with synchronized retroperfusion initiated 30 minutes after occlusion, and treatment was interrupted for 5 minutes at 1 hour after occlusion for study of the rapidity of retroperfusion response. Quantitative echographic analysis yielded global ejection fraction and regional indexes of contraction in a low left ventricular short-axis section, including segmental systolic area change, systolic wall thickening and end-diastolic wall thickness. At 6 hours after occlusion, ejection fraction had decreased from 50.7 +/- 4.9% to 28.1 +/- 7.7% (mean +/- standard deviation) in control dogs, but was significantly (p less than 0.01) less depressed in treated dogs (from 55.9 +/- 5.2 to 41.8 +/- 9.3%). The ischemic zone fractional area change at 30 minutes of occlusion exhibited a marked depression in both groups, after which the dysfunction persisted in the control dogs, but was largely reversed with retroperfusion from 6.0 +/- 6.5 to 35.9 +/- 15.9% at 6 hours of occlusion (p less than 0.01). Brief interruption of retroperfusion 1 hour after occlusion reduced ischemic zone fractional area change from 33.0 +/- 14.9 to 12.2 +/- 9.5% (p less than 0.01). This depression was promptly reversed to 33.6 +/- 12.2% when retroperfusion was resumed. Segmental wall thickening followed a similar trend.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of pressure-controlled intermittent coronary sinus occlusion on regional ischemic myocardial function.

Pressure-controlled intermittent coronary sinus occlusion has been reported to reduce infarct size in dogs with coronary artery occlusion, possibly because of increased ischemic zone perfusion and washout of toxic metabolites. The influence of this intervention on regional myocardial function was investigated in open and closed chest dogs. In six open chest dogs with severe stenosis of the left anterior descending coronary artery and subsequent total occlusion, a 10 minute application of intermittent coronary sinus occlusion increased ischemic myocardial segment shortening from 5.5 +/- 1.2 to 8.2 +/- 2.6% (NS) and from -0.1 +/- 2.1 to 2.3 +/- 1.2% (NS), respectively. In eight closed chest anesthetized dogs, intermittent coronary sinus occlusion was applied for 2.5 hours between 30 minutes and 3 hours of intravascular balloon occlusion of the proximal left anterior descending coronary artery. Standardized two-dimensional echocardiographic measurements of left ventricular function were performed to derive systolic sectional and segmental fractional area changes in five short-axis cross sections of the left ventricle. Fractional area change in all the severely ischemic segments (less than 5% systolic wall thickening) was -4.0 +/- 4.7% at 30 minutes after occlusion, and increased with subsequent 60 and 150 minutes of treatment to 13.1 +/- 3.3 and 7.0 +/- 3.3%, respectively (p less than 0.05). At the most extensively involved low papillary muscle level of the ventricle, regional ischemic fractional area change was increased by intermittent coronary sinus occlusion between 30 and 180 minutes of coronary occlusion from -0.4 +/- 0.1 to 14.4 +/- 4% (p less than 0.05), whereas a further deterioration was noted in untreated dogs with coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Early differentiation of infarcted and noninfarcted reperfused myocardium in dogs by quantitative analysis of regional myocardial echo amplitudes.

This study tests the hypothesis that ischemic but viable reperfused myocardium can be differentiated from infarcted reperfused myocardium by regional analysis of myocardial echo amplitudes. In eight closed-chest, anesthetized dogs, the left anterior descending coronary artery was occluded for 3 hours, followed by 1 hour of reperfusion, and sacrifice. Infarct size was measured by the triphenyl tetrazolium chloride technique in a 1-cm-thick mid-left ventricular transverse slice, and matched with a corresponding end-diastolic two-dimensional echo short-axis cross-section. Outlining of epi- and endocardial surfaces, along with construction of a mid-myocardial outline, allowed measurements of regional myocardial echo intensities and grey-level histograms in subendo- and subepicardial regions. In 36 eventually infarcted subendocardial segments (greater than 20% wall necrosis), average pixel intensity (arbitrary units) was 73.7 +/- 33.1 (SD) in control, 75.8 +/- 33.0 at 3 hours of occlusion, and 107.8 +/- 40.9 at 5 minutes, 105.5 +/- 38.9 at 15 minutes, and 101.1 +/- 37.6 at 60 minutes postreperfusion P less than 0.05 vs. control or occlusion); intensity in normal segments (no or less than 20% wall necrosis) was 60.0 +/- 18.6 in control, 57.4 +/- 20.3 at 3 hours of occlusion, and 63.5 +/- 14.8, 68.0 +/- 27.9, and 64.2 +/- 22.3 at 5, 15, and 60 minutes postreperfusion, respectively (no significant change). The skew of the grey-level distribution in infarcted subendocardial segments did not change from control (0.49 +/- 0.72) to 3 hours of occlusion (0.41 +/- 0.52), but decreased (shift to higher echo amplitude) significantly at 5 minutes (-0.31 +/- 0.53), 15 minutes (-0.22 +/- 0.50), and 60 minutes (-0.28 +/- 0.45) after reperfusion (P less than 0.05 vs. control or occlusion); in normal subendocardial segments, there was no significant change throughout the study. In 31 partly infarcted subepicardial segments (greater than 50% wall necrosis), changes in postreperfusion echo amplitudes were less significant. Average pixel intensity was 71.3 +/- 28.6 in control, 71.8 +/- 29.2 after coronary occlusion, and 89.2 +/- 35.3, 83.7 +/- 37.5, and 85.6 +/- 34.9 at 5, 15, and 60 minutes after reperfusion, respectively. It is concluded that reperfusion of irreversibly injured myocardium is associated with consistent early increase in regional myocardial echo intensities and changes in the grey-level distribution. Such alterations might be used to detect the extent of tissue necrosis within minutes after reperfusion.

Animals↗
PubMed1984

Regional differences in left ventricular response to atrial pacing in the dog: mapping of segmental function by two-dimensional echocardiography.

Two-dimensional echocardiography was applied in 10 closed-chest dogs to evaluate, in several left ventricular (LV) short-axis cross sections and subsegments, the regional contractile response to right atrial pacing. Compared with sinus rhythm (81 +/- 10 beats/min), which exhibited a moderate 7.2 +/- 12.0% (mean +/- standard deviation) base-to-apex increment in function, this gradient was significantly augmented to 34 +/- 12% by pacing at a heart rate of 180 beats/min. Measurements of wall thickening and perimeter shortening exhibited similar trends. Differences also were observed in subsegments of individual cross sections: in sinus rhythm the base-to-apex difference in function was relatively minor in the anterior and lateral aspects of the left ventricle (-9.1 +/- 18% and -1.9 +/- 19%), whereas a significant increase was noted in posterior and midseptal zones (18 +/- 17% and 22 +/- 30%). In response to pacing, the anterior and lateral wall base-to-apex gradients were significantly augmented (25 +/- 8% and 35 +/- 34%), but there was no further change in the posterior or septal regions. In conclusion, apical regions of the canine left ventricle responded to right atrial pacing with significant augmentation of contractile function, whereas more basal levels showed little response. Circumferentially, response to atrial pacing was most pronounced in the anterior and lateral segments.

Animals↗
PubMed1984

Retrograde coronary venous contrast echocardiography: assessment of shunting and delineation of regional myocardium in the normal and ischemic canine heart.

Coronary venous injections of sonicated Renografin-76 were performed in seven closed chest dogs during two-dimensional echocardiography to study the ability of this new technique to opacify regional myocardium before and after occlusion of the left anterior descending coronary artery. The balloon of a 4F double lumen catheter was inflated in the great cardiac vein for each contrast injection to prevent backflow through the coronary sinus into the right atrium. Retrograde injections before coronary artery occlusion generally resulted in patchy myocardial contrast uptake. Injections after coronary occlusion always resulted in confluent and transmural myocardial opacification which occupied 42.8 +/- 8.6% (range 26 to 54) (mean +/- standard deviation) of the myocardial circumference. Retrograde opacification always extended into adjacent myocardium beyond the ischemic zone, which was assessed in echocardiograms with antegrade contrast injections into the left main coronary artery and which measured 30 +/- 6.3% of the ventricular circumference. Shunting from the coronary venous system to cardiac chambers was evaluated in a parasternal four chamber view and was graded on a scale of 0 to 4+. Contrast appearance was equally intense in the right atrium and right ventricle (3.5 +/- 0.6+, range 2+ to 4+), less intense in the left ventricular cavity (1.5 +/- 0.6+, range 1+ to 3+) and absent in the left atrium. Postmortem anatomic validation with retrograde great cardiac vein injections of indocyanine green corroborated and in vivo contrast appearance in chambers. Retrograde coronary venous contrast echocardiography appears capable of providing in vivo information about the extent and location of myocardial zones that can be reached by retrograde infusions of therapeutic agents and about the ability of these agents to reach ischemic myocardium. In addition, this new method allows for in vivo evaluation of shunts between coronary veins and cardiac chambers, which may influence the efficacy of retrograde interventions.

Animals↗
PubMed1984

Microbubble dynamics visualized in the intact capillary circulation.

The potential for the use of contrast echocardiography to study myocardial perfusion has generated efforts to develop standardized echo contrast agents. The two methods used in this laboratory to generate microbubbles in solutions serving as contrast agents included the widely used hand-agitation method and the newer ultrasonic microcavitation (sonication) method. The latter has been demonstrated to generate smaller and more uniform microbubbles in an in vitro system. The present study was designed to observe, by direct microscopic examination of a cat mesentery preparation, the behavior and fate of the microbubbles in an in vivo system. The in vivo mesentery observations confirm the critical role of microbubble size in its unhindered passage through the capillary vasculature. The smaller and more uniform sonicated microbubbles passed rapidly through the microcirculation along with the red blood cells, whereas the larger microbubbles were observed to coalesce and interrupt the flow of blood and subsequently collapse or shrink.

Animals↗
PubMed1984

Computer methods for myocardial contrast two-dimensional echocardiography.

Two computer-aided videodensitometric methods that may be used in conjunction with two-dimensional contrast echocardiography were examined to quantify the time course of echographic opacification in the myocardium after experimental injections of contrast agents (hand-agitated Renografin-saline and sonicated sorbitol 70% solutions) into the left main coronary artery. Echographic studies of myocardial cross sections were digitized with an image processing computer using a 128 X 128 resolution matrix. Both stop frame and continuous cycle modes of acquisition were performed. A set of computer programs was developed to extract and analyze time-intensity curves from the digitized images. These included cardiac outline delineation, segmental division, regional intensity computation and exponential curve analysis. The stop frame method was applied to experimental studies in 17 closed chest dogs during control states and after coronary occlusions. Significant differences were found in the decay half-lives of echo intensity between normal (24 +/- 8 seconds) and acutely ischemic (293 +/- 165 seconds; p less than 0.001) myocardium for the Renografin-saline solution. Interobserver reproducibility of the measured half-lives was r = 0.91 and standard error of the estimate = 5 seconds. The continuous cycle method of analysis was examined in five closed chest dogs (with up to six injections per dog), applying the sonicated sorbitol 70% solution in only the control state. The mean half-life was 4.2 +/- 1.1 seconds. These computer-based videodensitometric methods might be applied to a wide variety of experimental studies in two-dimensional contrast echocardiography that attempt to quantify myocardial perfusion and function.

Animals↗
PubMed1984

Myocardial contrast two-dimensional echocardiography: experimental examination at different coronary flow levels.

Regional myocardial echo contrast appearance-disappearance after intracoronary contrast agent injection was examined with computerized two-dimensional contrast echocardiography in eight open chest dogs during successive variation of the coronary blood supply. A new sonication method applied to dextrose 50% produced an echo contrast agent with a microbubble size of 12 +/- 6 mu (mean +/- standard deviation), and 1 cc of this agent was injected into a coronary artery during the echocardiographic study of the left ventricle. Left anterior descending or circumflex coronary artery flow, measured by electromagnetic flowmeter, was successively reduced up to 90% with an extravascular hydraulic occluder, or else increased 40 to 60% through intravenous dipyridamole infusion (7 to 10 micrograms/kg per min). The corresponding myocardial echo time-intensity curves were analyzed for each of 12 segments of a midventricular short-axis cross section. Several potential indexes of myocardial perfusion were derived: peak echo contrast intensity, time from echo contrast appearance to peak intensity, half-life of echo contrast decay phase (T 1/2) and total duration of contrast appearance-disappearance. Except for peak intensity, all of these indexes provided significant (p less than 0.05) differentiation between control coronary flow (66 +/- 17 ml/min) and greater than 50% flow reductions (26 +/- 6 ml/min) or hyperemia (115 +/- 17 ml/min). Half-life values were 5.2 +/- 0.3 seconds for the control state, 9 +/- 2 seconds for the reduced coronary flow and 2 +/- 2 seconds for dipyridamole hyperemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Increased regional end-diastolic wall thickness early after reperfusion: a sign of irreversibly damaged myocardium.

Two-dimensional echocardiographic measurements of regional left ventricular end-diastolic wall thickness and systolic wall thickening were studied during coronary artery occlusion and early after reperfusion and compared with measurements of regional myocardial infarct size. In 25 closed chest anesthetized dogs with left anterior descending coronary artery occlusion followed by reperfusion, the occlusion period was 3 minutes in group I (n = 4), 20 minutes in group II (n = 4), 60 minutes in group III (n = 5) and 180 minutes in group IV (n = 12). Infarct size in groups III and IV was quantitated using the triphenyltetrazolium chloride technique. After coronary occlusion, wall thickening was replaced by thinning in the center of the ischemic region at the midpapillary echographic short-axis section, and no improvement in function occurred up to 60 minutes after reperfusion, except in group I. Ischemic zone end-diastolic wall thickness did not change significantly from control to the end of the coronary occlusion period, except Group IV. At 60 minutes after reperfusion, end-diastolic wall thickness increased only slightly in groups I and II (by 7.2 and 0.24%, respectively), but a marked increase was observed in groups III and IV (by 41 and 50%, respectively). The percent change in ischemic zone end-diastolic wall thickness from before reperfusion to 60 minutes after reperfusion correlated well with the amount of myocardial necrosis in corresponding segments (r = 0.936, standard error of estimate = 11.4%); an increase in segmental end-diastolic wall thickness of more than 25% was generally associated with 20% or more segmental necrosis. It is concluded that significantly increased regional end-diastolic wall thickness early after reperfusion is associated with irreversibly damaged myocardium, and this might be used as an index of myocardial salvage.

Animals↗
PubMed1984

Hyperemic response of intracoronary contrast agents during two-dimensional echographic delineation of regional myocardium.

Several intracoronary echo contrast agents that provided satisfactory regional myocardial delineation with two-dimensional echocardiography were compared in 15 dogs and their effects on coronary blood flow were examined. Reproducible delineation of myocardium subserved from the intracoronary echo contrast injection site was achieved with hand-agitated agents containing greater than or equal to 30% Renografin, greater than or equal to 30% glucose, greater than or equal to 30% sucrose or 6% dextran. After a 2 cc injection of the echo contrast agent, peak hyperemic augmentation of coronary flow was 56.7 +/- 54.4% for 6% dextran, 116.0 +/- 71.1% for 30% Renografin, 119.3 +/- 47.8% for 30% sucrose, 173.8 +/- 38.3% for 30% glucose. Although, 6% dextran resulted in the lowest and shortest hyperemic response of the four agents, computer-derived echo contrast appearance-disappearance analysis indicated a prolonged myocardial contrast decay half-life (21.0 seconds). On the other hand, 30% Renografin had a more rapid myocardial echo contrast washout (T 1/2 = 15.5 seconds), but a significantly greater hyperemic effect was observed. It is concluded that development of echo contrast agents for myocardial contrast two-dimensional echocardiographic assessment of myocardial perfusion will require consideration of alterations in coronary flow due to contrast-induced hyperemia.

Animals↗
PubMed1984

Physical factors influencing quantitation of two-dimensional contrast echo amplitudes.

Measurement errors that may interfere with quantitation by the new myocardial contrast two-dimensional echocardiographic technique were examined in a simplified in vitro model consisting of a 50 cc blood-filled balloon with supplemental controlled injection of 0.2 to 2.6 cc of sonicated dextrose 70%. The blood-contrast mixture in the balloon volume was imaged with two-dimensional echocardiography and discrete regions were studied for both magnitude and time course of echo intensities. Preliminary evidence indicates that a regional contrast echo intensity measurement is significantly modified by contrast-related ultrasound attenuation in intervening regions and by the amount and mode of contrast material injection. Thus, injection of 1.2 cc contrast material resulted in substantially higher peak echo intensity and a more rapid decay than injection of 0.8 or 0.6 cc. These measurements were also found to be influenced by the echographic system signal processing and time-gain compensation which contribute to nonlinear and unevenly compensated image distribution of echo amplitudes. Other factors are discussed, including transducer-related image resolution and image texture, contrast agent bubble size and persistence and computer methods for standardized selection of region of interest and analysis of the regional contrast intensity decay curve.

Blood↗
PubMed1984

Prostaglandin E1 coronary venous retroperfusion in acute myocardial ischemia: effects on regional left ventricular function and infarct size.

Prostaglandin E1 was administered by means of coronary venous synchronized retroperfusion and the effectiveness of the combined (prostaglandin-retroperfusion) system was examined during acute myocardial ischemia in 10 closed chest anesthetized dogs. Such treatment was administered between 30 minutes and 3 hours after occlusion of the proximal left anterior descending coronary artery. An equivalent series of 10 dogs with arterial blood retroperfusion alone and 9 untreated dogs served as control subjects. Standardized two-dimensional echocardiographic measurements of global and regional left ventricular function were performed in five short-axis cross sections. The global low left ventricular section and its profoundly ischemic anterolateral region exhibited distinctly improved systolic fractional area changes as a result of the prostaglandin E1 retroperfusion treatment between 30 minutes and 3 hours after occlusion (22.9 +/- 1.5 to 41.2 +/- 4.0% and 1.8 +/- 3.6 to 29.4 +/- 5.6%, respectively). In contrast, further deterioration in function was noted during an untreated equivalent coronary occlusion period (16.3 +/- 2.7 to 10.0 +/- 3.3% and 12.6 +/- 6.1 to 4.1 +/- 6.9%). Although arterial blood retroperfusion alone provided distinct benefits in the ischemic region of a midpapillary echo section (from 13.4 +/- 3.9 to 32.1 +/- 10.4%, p less than 0.05), no improvements were observed in profoundly jeopardized segments at the low left ventricular level (5.6 +/- 6.0 to 0.9 +/- 5.7%). Triphenyltetrazolium chloride delineation of infarction revealed significant myocardial salvage with prostaglandin E1 retroperfusion as compared with findings in untreated control dogs (3.7% +/- 1.3% of the left ventricle versus 9.3 +/- 1.9%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1984

Two-dimensional echocardiographic contrast assessment of pacing-induced mitral regurgitation: relation to altered regional left ventricular function.

Two-dimensional echocardiography during agitated saline contrast injections into the left ventricle was applied in eight closed chest dogs to examine the degree of mitral valve regurgitation encountered with pacing from two sites: 1) at the right ventricular apex and 2) within the coronary sinus at the base of the left ventricle. Pacing was at a rate of 10 beats/min above the sinus rate, and ranged from 60 to 120 beats/min. Hemodynamic variables were monitored, and data on global and regional left ventricular function were derived from a series of short- and long-axis cross-sectional echographic images. The degree of valvular regurgitation was assessed independently by two observers, and systolic appearance of echo contrast in the left atrium was graded as 0 to +4. Although no mitral regurgitation was noted in sinus rhythm, regurgitation was severe with right ventricular apical pacing (3.2 +/- 0.7, mean +/- standard deviation) and relatively mild (0.9 +/- 0.7) with basal pacing (p less than 0.01 and 0.05, respectively). Relative to sinus rhythm, thermodilution stroke volume was significantly (p less than 0.05) depressed by both apical and basal pacing (from 32.6 +/- 14.6 to 25.0 +/- 7.9 and 26.0 +/- 7.6 cc, respectively), but there was no significant difference between the two pacing sites. Mapping of regional function at six levels of the left ventricle revealed significant heterogeneities, with maximal dysfunction noted in the vicinity of the pacing site. It is concluded that significant differences in mitral regurgitation exist depending on the site of pacing, with apical pacing causing severe regurgitation and abnormal regional contraction near the pacing site.

Animals↗
PubMed1984

Two-dimensional contrast echocardiography. I. In vitro development and quantitative analysis of echo contrast agents.

To facilitate the passage of echo contrast agents through the microcirculation and the echocardiographic study of myocardial perfusion, ultrasonic energy (sonication) was employed to produce contrast agents consisting of relatively uniform, stable and small (less than 10 mu diameter) gaseous microbubbles suspended in liquid solutions. The size and persistence of the microbubbles was verified by light microscopy and an in vitro system were employed for comparative assessment of peak echo amplitude and echo persistence characteristics of various contrast agents. The study indicated that although a variety of hand-agitated and sonicated contrast agents provided satisfactory echo intensities, sonication was clearly superior to the hand-agitation method, because sonication produced smaller, more uniform and more stable microbubbles that may be suitable for myocardial contrast echocardiography. It is concluded that of the contrast agents examined, sonicated solutions of sorbitol (70%) and dextrose (70%) appeared to have particular potential because of the small sizes of the microbubbles (6 +/- 2 and 8 +/- 3 mu, respectively) and their prolonged in vitro persistence. The use of sonication to produce standardized, small and stable microbubbles should facilitate physiologic passage of the contrast agent through the capillary beds and allow two-dimensional imaging of the left heart myocardium during right-sided, aortic root, coronary sinus or intracoronary contrast injections.

Contrast Media↗
PubMed1984

Two-dimensional contrast echocardiography. II. Transpulmonary studies.

A method using contrast two-dimensional echocardiography for left ventricular chamber and myocardial opacification from a right-sided pulmonary capillary wedge position is described. A total of 152 studies were carried out in nine mongrel dogs. Four different catheters with different catheter tip cross-sectional areas (varying from 0.75 to 2.3 mm2) were used. In addition, catheter position (six different positions in the pulmonary circulation), pressure of injection and type of echo contrast agent (hand-agitated and sonicated) were studied. In all 152 studies, two independent observers agreed that echo contrast was seen in the left ventricular chamber after a pulmonary capillary wedge injection of 8 cc of echo contrast agent followed by a flush injection of 8 cc saline solution. In 71% of the studies, the two independent observers agreed about the degree of opacification on a qualitative scale of 0 to 3+. Time from injection from the catheter tip to the appearance of echo contrast in the left atrium was 6.2 +/- 4.8 seconds for sonicated Renografin-76 and 2.8 +/- 0.6 seconds for sonicated sorbitol 70% (p less than 0.05). Correlation for the disappearance rate of echo contrast as determined for the region in the mid left ventricular chamber and thermodilution cardiac output was fair (r = -0.78; n = 14). In 24 studies, it was not possible to demonstrate the appearance of echo contrast in the myocardium. Peak videointensity of 10 duplicate injections showed a mean percent error of 10.4 +/- 2.1% for sonicated Renografin-76 and 1.4 +/- 0.8% for sonicated sorbitol 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Verification of myocardial contrast two-dimensional echocardiographic assessment of perfusion defects in ischemic myocardium.

Myocardial contrast two-dimensional echocardiography was used in 21 closed chest dogs to assess its ability to delineate the extent of underperfused acutely ischemic myocardium. An agitated saline-Renografin echocardiographic contrast agent was injected into the left main coronary artery after left anterior descending coronary artery occlusion, and the size of the contrast echo-free area characterizing the perfusion defect was outlined in short-axis cross sections of the left ventricle. In 13 dogs, monastral blue dye was injected after 45 minutes of coronary artery occlusion and before sacrifice to provide anatomic delineation of underperfused zones in equivalent sections. Perfusion defects assessed by contrast two-dimensional echocardiography correlated well with those delineated by monastral blue dye (r = 0.91). Contrast echocardiographic study was also performed in eight other dogs at 5 hours of occlusion, after which infarct size was measured with triphenyl-tetrazolium-chloride. Contrast echocardiographic outline of the perfusion deficiency correlated but slightly overestimated the extent of necrosis (r = 0.88). It is concluded that contrast two-dimensional echocardiography can detect and outline the underperfused "risk area" during acute coronary artery occlusion, and may also permit assessment of the extent of myocardial infarction.

Animals↗
PubMed1984

Correlation of myocardial echo contrast disappearance rate ("washout") and severity of experimental coronary stenosis.

The relation between experimental coronary stenosis and myocardial contrast echo disappearance rate ("washout") was investigated in anesthetized closed chest dogs. Of 13 dogs, 8 had serial contrast echographic studies with two successive degrees of coronary stenosis (50 and 70%) produced by threading stenotic plugs into the proximal left circumflex coronary artery. Studies were repeated with complete coronary occlusion achieved by inflation of an intracoronary balloon immediately proximal to the plugs. Myocardial contrast echograms were recorded in short-axis cross sections of the left ventricle after intracoronary injection of 2 ml hand-agitated saline-Renografin solution through a catheter placed in the coronary artery. An echo contrast washout index (t 1/2) was measured by digital processing computer analysis of successive end-diastolic images obtained by two-dimensional echocardiography during myocardial contrast agent injection. The injection to injection correlation coefficient of these t 1/2 measurements was satisfactory (r = 0.87, standard error of estimate 4.8 seconds). Involved segment t 1/2 measurements were found to be significantly altered by intracoronary stenosis and occlusion, ranging from 23 +/- 6 seconds (mean +/- standard deviation) in the control state, 29 +/- 9 and 44 +/- 10 seconds for 50 and 70% stenosis, respectively, and 104 +/- 35 seconds for total occlusion. It was concluded that myocardial contrast two-dimensional echocardiographic measurement of t 1/2 appears to be a useful index of the degree of coronary stenosis.

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