Assessment of transesophageal Doppler echography in dissecting aortic aneurysm.

To assess the clinical value of transesophageal Doppler echography in the diagnosis of dissecting aortic aneurysm, both transesophageal and conventional echograms were performed in 22 cases of dissecting aortic aneurysm. Of the 22 patients, 17 underwent angiography; 8, X-ray computed tomography; 4, both; and 12, surgery. The performance of each method was assessed in the following four segments: A, ascending aorta; B, aortic arch; C, thoracic descending aorta; and D, upper abdominal aorta. The results by angiography were presumed to be correct. In the group of 17 patients who underwent angiography, the rate of correct detection of an intimal flap using the transesophageal approach was 100% in all four segments, significantly better than detection by the conventional approach (segment A, 65%; segment B, 47%; segment C, 35%; segment D, 53%) (p less than 0.01), and the rate of correct detection of the entry sites using the transesophageal approach was 100%, significantly better than that by conventional approach (42%) (p less than 0.05). X-ray computed tomography was not capable of detecting the site of entry in all cases. The presence of thrombus, aortic regurgitation and pericardial hemorrhage were all revealed clearly by the transesophageal approach, and the results were partly proved by other methods. In conclusion, transesophageal Doppler echography provides a rapid and accurate method of diagnosing and evaluating dissecting aortic aneurysm and permits prompt initiation of appropriate treatment.

Modification of regional function of ischaemic myocardium by the alteration of arterial pressure in dogs.

The effects of alterations of arterial pressure by nitroprusside and methoxamine on regional myocardial function were studied during total coronary occlusion and during partial coronary constriction in open chest dogs. Animals were instrumented with a left ventricular micromanometer, an electromagnetic flow probe around the left circumflex coronary artery, and three pairs of ultrasonic crystals in a control, marginally ischaemic, and ischaemic segments. In nine dogs, when the coronary artery was totally occluded by a hydraulic cuff placed distal to the flow probe, the end-diastolic length of all three segments was increased, and shortening was rapidly replaced by systolic expansion in the ischaemic segment. Active shortening decreased by 68% in the marginal segment, while it increased by 21% in the control segment. With nitroprusside infusion, peak systolic pressure was reduced from 15.2 to 11.3 kPa and hypokinesis of the marginal segment was improved to 45% of control value with a concomitant decrease in end-diastolic length by 5%. With methoxamine, left ventricular systolic pressure was elevated to 18.5 kPa, and marginal segment shortening further deteriorated to 19% of control with chamber enlargement. In 6 dogs, coronary flow was limited by a screw-driven metal clamp. When mean coronary flow was reduced by 50% of control value, stable hypokinesis was produced in the ischaemic segment. Nitroprusside infusion induced the same haemodynamic changes, however, shortening of the ischaemic segment deteriorated further and a passive bulge appeared. Methoxamine improved the percentage shortening from 1.2 to 6.4%. Thus, interventions with an agent which changes afterload in left ventricular ejection have multiple and complex effects on the contractile function of the ischaemic myocardium and, depending on the magnitude of coronary blood flow reduction, a potentially beneficial drug can be determined to an ischaemic myocardium.

Effects of intraaortic balloon counterpulsation on regional myocardial function during acute coronary occlusion in the dog.

The effects of intraaortic counterpulsation on regional myocardial function were studied using ultrasonic dimension gauges in 24 open chest dogs. Pairs of ultrasonic crystals were implanted in the subendocardium of the left ventricle in control, marginally ischemic and ischemic segments. After coronary arterial occlusion, the end-diastolic length of all three segments was increased. Segment shortening was rapidly replaced by systolic expansion in the ischemic segment. In the marginal segment, active shortening decreased by 53% and, in the control segment, shortening was augmented by compensatory operation of the Frank-Starling mechanism. Balloon pumping initiated 10 minutes after coronary occlusion resulted in an increase in mean aortic diastolic pressure from 103 to 115 mm Hg without any significant change in peak systolic pressure. In the marginal segment, end-diastolic length decreased by 3%, and previously reduced shortening increased to 82% of control value, deteriorating again with discontinuation of counterpulsation. Balloon pumping produced no change in the dyskinetic motion of the ischemic segment but caused compensatory augmentation of shortening of the control segment. Thus, counterpulsation selectively improved segment function of the marginally ischemic segment, presumably as a result of a regional increase in myocardial blood flow and in availability of oxygen due to augmented perfusion pressure. The systolic unloading effect was counterbalanced by improved cardiac performance.

Detection of intracardiac shunt flow in atrial septal defect using a real-time two-dimensional color-coded Doppler flow imaging system and comparison with contrast two-dimensional echocardiography.

To evaluate the noninvasive detection of shunt flow using a newly developed real-time 2-dimensional color-coded Doppler flow imaging system (D-2DE), 20 patients were examined, including 10 with secundum atrial septal defect (ASD) and 10 control subjects. These results were compared with contrast 2-dimensional echocardiography (C-2DE). Doppler 2DE displayed the blood flow toward the transducer as red and the blood flow away from the transducer as blue in 8 shades, each shade adding green according to the degree of variance in Doppler frequency. In the patients with ASD, D-2DE clearly visualized left-to-right shunt flow in 7 of 10 patients. In 5 of these 7 patients, C-2DE showed a negative contrast effect in the same area of the right atrium. Thus, D-2DE increased the sensitivity over C-2DE for detecting left-to-right shunt flow (from 50% to 70%). However, the specificity was slightly less in D-2DE (90%) than C-2DE (100%). Doppler 2DE could not visualize right-to-left shunt flow in all patients with ASD, though C-2DE showed a positive contrast effect in the left-sided heart in 9 of 10 patients with ASD. Thus, D-2DE is clinically useful for detecting left-to-right shunt flow in patients with ASD.

Detection and evaluation of tricuspid regurgitation using a real-time, two-dimensional, color-coded, Doppler flow imaging system: comparison with contrast two-dimensional echocardiography and right ventriculography.

To detect and evaluate regurgitant flow in tricuspid regurgitation (TR) with a newly developed, realtime, 2-dimensional (2-D), color-coded, Doppler flow imaging system (Doppler 2-D echo), 27 patients (18 with suspected TR and 9 normal subjects) were examined and the findings were compared with those obtained using contrast 2-D echocardiography (contrast 2-D echo) and right ventriculography. In 16 of 18 patients with suspected TR, Doppler 2-D echo easily visualized the color-coded regurgitant flow in the right atrium and estimated the severity of TR from the distance of the visible TR jet. On the basis of the QRS synchronized appearance of contrast in the inferior vena cava by the subxiphoid approach or of the negative contrast effect above the tricuspid valve just after the contrast entered the right ventricle with its subsequent back-and-forth movements across the tricuspid valve, Doppler 2-D echo was more sensitive and specific in detecting TR (100% and 100%) than contrast 2-D echo (75% and 82% in the subxiphoid view, 56% and 100% in the 4-chamber view) when the fast Fourier transformation frequency analysis was used as the standard of TR, and it was more sensitive in detecting TR (85%) than contrast 2-D echo (69% in the subxiphoid approach, 46% in the 4-chamber view) when right ventriculography was used as the standard of TR. Additionally, the severity of TR as shown by Doppler 2-D echo correlated fairly well with that shown by right ventriculography. Thus, Doppler 2-D echo is clinically useful for detecting and evaluating TR.

End-systolic dimension-wall thickness relations during myocardial ischemia in conscious dogs. A new approach for defining regional function.

Overall and regional left ventricular (LV) function was studied during progressive coronary stenosis in conscious dogs by determining the relations at end-systole between LV pressure, chamber dimensions, and regional LV wall thickness. An index of regional wall stress was also analyzed. Using ultrasonic dimension gauges, measurements were made of LV wall thickness in control and ischemic regions, and the external long- and short-axis LV diameters were determined; an implanted micromanometer measured LV pressure. Internal LV diameters were obtained from the external diameters by subtraction of wall thickness, and the index of regional wall stress employed a thick-walled ellipsoidal model. During regional ischemia, the LV long axis at end-systole did not change, whereas the short-axis diameter progressively increased (from 24 +/- 7 mm [standard deviation] to 30 +/- 9 mm, p less than 0.001, indicating a more spherical LV shape during ischemia). The end-systolic pressure did not change, and therefore the end-systolic pressure-diameter relation shifted progressively, suggesting a global decrease in LV contactility. The end-systolic points relating LV wall thickness in the ischemic region to the end-systolic LV pressure revealed the regional nature of the abnormality, showing a progressive displacement to the left, whereas there was no significant displacement of this relation in the control region. The application of this index over a range of loading conditions during partial vena caval occlusion was illustrated. Thus, the regional end-systolic wall thickness-pressure relation provides a new index for defining the regional contractile state of the LV myocardium which is potentially load-independent and offers the possibility for echocardiographic application.

Recognition of regional hypertrophy in hypertrophic cardiomyopathy using thallium-201 emission-computed tomography: comparison with two-dimensional echocardiography.

The configuration of the hypertrophied myocardium was evaluated by thallium-201 emission-computed tomography and 2-dimensional (2-D) sector scan in 10 patients with obstructive hypertrophic cardiomyopathy (HC), 10 with nonobstructive HC with giant negative T waves and 10 with concentric left ventricular (LV) hypertrophy. Thallium-201 myocardial imaging was reconstructed into multiple 12-mm-thick slices in 3 planes. The thickness ratio of the ventricular septum and the LV posterior wall in the short-axis plane and the ratio of the ventricular septum and the apical wall in the long-axis plane were analyzed. In the patients with obstructive HC the ventricular septal wall thickness index was increased, and the ratio of septal to posterior wall thickness index (1.45 +/- 0.23) was greater than that in the patients with nonobstructive HC with giant negative T waves or in those with concentric LV hypertrophy (1.03 +/- 0.20 and 0.98 +/- 0.11, respectively; p less than 0.01 for each). In the patients with nonobstructive HC with giant negative T waves, increased apical wall thickness with apical cavity obliteration was characteristic, and the ratio of ventricular septal to apical wall thickness index (0.66 +/- 0.14) was less than that in the patients with obstructive HC or in those with concentric LV hypertrophy (1.46 +/- 0.38 and 1.04 +/- 0.09, respectively; p less than 0.001 for each). In contrast, technically satisfactory 2-D sector scanning (83%) demonstrated various configurations of the hypertrophied ventricularseptum, but could not detect apical hypertrophy in 4 of the 10 patients with nonobstructive HC with giant negative T waves whose LV cineangiograms demonstrated apical hypertrophy. Thus, thallium-201 emission-computed tomography is useful in evaluating the characteristics of LV hypertrophy and assists 2-D sector scan, especially in patients with apical hypertrophy in HC.

Primary chylopericardium.

In a 23-year-old man with massive chylous pericardial effusion, oral administration of Sudan III and radio-active 131iodine-labelled triolein revealed an abnormal communication between the lymphatic system and the pericardial sac. Despite partial pericardiectomy and resection of the thoracic duct, the fluid reaccumulated, and a postoperative lymphangiogram showed an obstructed left thoracic duct. Resection of this left thoracic duct resulted in full recovery. This is the first reported case of this disease with a duplicate thoracic duct. Careful attention must be paid to the possibility of this variation before and during surgery.

Dynamic changes in left ventricular regional wall thickness during premature ventricular contraction in conscious dogs.

The contractile pattern of the regional left ventricular wall during premature ventricular contraction was analyzed in conscious dogs instrumented with an ultrasonic dimension gauge across the anterior and posterior left ventricular walls. Aortic flow was measured with an electromagnetic flow probe. A single premature ventricular contraction was induced by stimulating either the anterior or posterior wall with varied coupling intervals from 380 to 650 msec. Stroke volume of premature ventricular contraction was significantly smaller than that of premature atrial contraction with identical coupling intervals. In premature contractions, stroke volume was linearly related to coupling intervals. Though there was no isovolumic wall thickening in premature atrial contraction, the wall started to thicken during isovolumic ventricular systole in premature ventricular contraction. There was a clear inverse correlation between the ratio of the isovolumic wall thickening to the total wall thickening and coupling intervals. In premature ventricular contractions with identical coupling intervals, the deformation of thickening characteristics was more pronounced in regions with closer proximity to the ectopic focus. Thus it is concluded that the pump function is depressed in premature ventricular contraction, in part due to the increased ratio of wall thickening during isovolumic systole before the opening of the aortic valve. Isovolumic wall thickening increases along with the shorter coupling intervals and closer proximity to the ectopic focus. These alterations in left ventricular mechanical function due to ectopic contraction might induce serious sequelae, depending upon the ectopic focus in the presence of already depressed regional function.

Left ventricular geometry during partial and complete coronary occlusion in the conscious dog.

Seven dogs were instrumented with a left ventricular micromanometer and pairs of ultrasonic crystals to measure left ventricular wall thicknesses (control and ischemic regions) and short and long left ventricular axes; cuff occluders were placed around the left circumflex coronary artery and the inferior vena cava. Measurements were performed at rest, after 2 min of partial and complete coronary occlusion, and 1 and 10 min after release of partial and complete coronary occlusion. Left ventricular wall thickness in the ischemic region showed reduced systolic thickening during partial coronary occlusion and systolic thinning during complete coronary occlusion. During diastole, at zero pressure (inferior vena cava obstruction) the left ventricular short axis was unchanged during partial coronary occlusion but significantly increased (creep) during complete coronary occlusion (P less than 0.05), whereas after release of both partial and complete coronary occlusion the short axis at zero pressure decreased significantly (P less than 0.025). Left ventricular wall thickness at zero diastolic pressure in the ischemic region was significantly thinner during complete coronary occlusion than during control and significantly thicker (reactive hyperemia) 1 min after release of both partial and complete coronary occlusion. The long left ventricular axis remained unchanged during the entire experiment. At end-diastole, the long/short axis ratio was normal during partial (1.72; control 1.68; NS) and complete coronary occlusion (1.69; NS), but it decreased significantly from control of 2.10 to 1.99 with partial coronary occlusion and 1.85 with complete coronary occlusion (P less than 0.01). The changes in the L/S ratio during partial and complete coronary occlusion were proportional to changes in left ventricular chamber volume (correlation coefficient 0.94). Our data show that left ventricular shape remains normal at end-diastole during partial and complete coronary occlusion but becomes significantly more spherical at end-systole, with reduction of the normal tendency for the ventricle to become more elliptical during systole. These elliptical and spherical shape changes of the left ventricle during partial and complete coronary occlusion appear to be closely related to the chamber volume.

[Computer analysis of echocardiograms].

Owing to its non-invasive nature, echocardiography, is widely used in many fields of clinical sciences. Especially in cardiology, real-time pictures of the beating heart are now essential in clinical practice. With recent developments of computer technology, various aspects of computerization have been introduced into echocardiography. Analysis of cardiac function became easier by automated echocardiography with three dimensional framework, length-tension-velocity. A 3-dimensional view of the heart could also be obtained by computerized image processing of serial echocardiograms. The results of the automated analysis by computer were in good agreement with those with manual measurements. Therefore, the computer processing is valid. These kinds of computer image processing of echocardiograms would be useful in various clinical settings.

[Pathophysiological analysis of cardiac function by computer processing of echocardiograms].

Automatic image processing system has been developed for analysis of cardiac function with echocardiograms. Echograms of apical long axis view were transferred to microcomputer system and processed to display three dimensional images of left ventricular myocardium. With this technology, analysis of left ventricular wall thickness in three dimensional manner revealed pathophysiological changes in ischemic heart disease.

[Dynamics of the interventricular septum in mechanical overload].

To assess wall thickness dynamics of the interventricular septum, ultrasonomicrometry was directly applied to measure wall thickness of the septum as well as the left ventricular free wall thickness in open chest dogs. In the control resting state, the end-diastolic wall thickness and magnitude of the systolic thickening of the septum were essentially equal to those of the left ventricular free wall. Acute interventions, such as pressure or volume overloading on the right or left ventricle, induced the same dynamic changes in the septum as in the left ventricular free wall. To evaluate the chronic changes in wall thickness dynamics of the interventricular septum, echocardiographic studies were conducted in patients with chronic pressure or volume overload in the right or left ventricle. While sustained pressure or volume overload in the left ventricle resulted in an increase in wall thickness of both the septum and left ventricular free wall, chronic pressure overload of the right ventricle induced the hypertrophy only in the septum but not in the left ventricular free wall. Thus, the interventricular septum can be regarded as a functional part of the left ventricle, and the mechanical loading on the left ventricle will ultimately induce proportional changes in the septum and the left ventricular free wall. Although the septal function is largely independent of acute changes in right ventricular loading, a chronic effect cannot be ignored.

Acute aortic regurgitation with congestive heart failure due to bacterial endocarditis: diagnosed by echocardiogram and treated successfully by surgery (a case report).

A 23-year-old Japanese male with no evidence of previous heart disease was presented with bicuspid aortic valve and a life threatening acute aortic regurgitation due to subacute bacterial endocarditis. By echocardiographic techniques, a precise diagnosis was made based on the following findings: 1) premature mitral valve closure, 2) snowfall-like echoes between the systolic aortic cusps, 3) eccentricity of a diastolic aortic valvular echo. The echocardiographic diagnosis was confirmed on surgery, in which aortic valve replacement was performed with satisfactory postoperative results.

[Left ventricular wall thickness in hypertrophic cardiomyopathy: comparisons of measurements by magnetic resonance imaging, cineangiography, and echocardiography].

To evaluate the usefulness of magnetic resonance imaging (MRI) in measuring regional wall thickness of the left ventricle, 11 patients with hypertrophic cardiomyopathy (HCM) were imaged. The measurements were compared with those obtained by two-dimensional echocardiography (2D-echo) and cineangiography. Regional wall thickness was ascertained at six locations including the base, middle, and apex of the interventricular septum (IVS) and left ventricular posterior wall (LVPW) from the two selected transverse sections. All of these six locations were also measured for the IVS by biventriculography and for the LVPW by left ventriculography with the left anterior oblique view. Only the base was measured for both the IVS and LVPW using 2D-echo because of the difficulty in obtaining good images for the middle and apex of the left ventricle. The measurements by MRI correlated well with those obtained by 2D-echo and cineangiography in the majority of locations. At the base, where the wall thickness was measured by the three methods, the measurements of the IVS correlated well each other (r = 0.63 to 0.81). However, a good correlation was obtained only between 2D-echo and MRI for the LVPW r = 0.75. The correlation between MRI and cineangiography was generally good for the IVS at any levels (r = 0.76 to 0.87), but not for the LVPW. This was partially due to the narrow range of data for the LVPW as well as to the difficulty in determining the epicardial border in left ventriculograms. In conclusion, regional wall thickness can be correctly measured by MRI in any locations of the left ventricle even at the apex, where measurement is difficult by other methods.

Nonuniformity of inner and outer systolic wall thickening in conscious dogs.

Transmural differences in systolic wall thickening were analyzed in 13 conscious dogs by implanting sonomicrometers to continuously measure total wall thickness (WT) and outer WT approximately half the distance through the myocardium at a closely adjacent location. Inner WT was derived by subtraction of outer WT from total WT. Outer wall measurements spanned, on average, the outer 44 +/- 10% (+/- SD) of the wall; derived inner wall measurements spanned the remaining 56 +/- 10%. At rest the fractional contribution (FC) of the outer wall to total systolic wall thickening was 29 +/- 9%, which was significantly less than the FC of the inner wall, 71 +/- 9%. These data are in good agreement with simplified modeling of a cross section of the left ventricle as two concentric rings that predicts that the FC of inner and outer halves of the wall should be approximately 67 and 33%, respectively. During treadmill exercise, the extent of both inner and outer thickening increased significantly (30 and 29%, respectively) but the relative FC of the inner and outer wall remained the same. The data indicate that systolic wall thickening is nonuniform and that this nonuniformity remains constant during the increased inotropic and chronotropic stimulation associated with exercise.

Cyclical coronary flow reductions in conscious dogs equipped with ameroid constrictors to produce severe coronary narrowing.

In conscious dogs equipped with ameroid constrictors to produce gradual coronary occlusion, coronary flow velocity was monitored prior to complete occlusion when coronary constriction was severe (resting flow velocity reduced by 10-50% from control recordings made days after ameroid implantation). In six of the ten dogs, we observed spontaneous cyclical variations in coronary flow velocity, characterized by gradual reduction in flow followed by very abrupt restoration of flow. The cyclic coronary flow reductions were observed between 20 and 31 days after ameroid implantation. These changes in flow bear striking similarity to those observed by previous investigators using anesthetized, open-chest canine preparations, in which the role of platelets was clearly demonstrated. Consequently, we hypothesize that spontaneous platelet aggregation and de-aggregation within the severely narrowed coronary lumen (enclosed by the ameroid constrictors) could account for our observations.

[Determination of left ventricular center of contractile motion by two-dimensional echocardiography].

To quantify left ventricular (LV) regional wall motion using two-dimensional echocardiography, reference points such as the center of left ventricular gravity or an intersecting point of radial grids were conventionally used, assuming that they were near or at the center of LV contractile motion. However, since the LV does not contract homogeneously, their positions might be quite different. Endocardial high density spots in two-dimensional echocardiograms were used as markers for LV regional wall motion, and we determined the center of LV contractile motion (C) at papillary muscle level in the parasternal short-axis view for 10 normal subjects (control group) and eight patients with aortic regurgitation (left ventricular volume overload; LVVO group). In one subject, each of six endocardial high density spots extracted from different LV regions, and were traced frame by frame throughout one cardiac cycle using a video motion analyzer, and their systolic movements were shown by six vectors. Using the method of least squares, the point of convergence of vectors (C) was determined from the point toward which the six vectors were directed. The LV centers of gravity at end-diastole (Ged) and at end-systole (Ges) were also determined by tracing the endocardial surface on video frames. The distributions of C, Ges, and Ged were compared. In the control group, point C was at the point 35% distant from Ged toward the middle of the interventricular septum (IVS). Ges deviated from Ged in the same direction as point C, but the distance was one third of C(11%). In the LVVO group, the distribution of Ges referred to Ged was similar to that of the control group, however, point C was closer to Ged, since its deviation was 16% of the radius. These results suggest that point C, which is determined by the directions of regional wall motion, reflects the contractile pattern of the whole LV. This might be termed the center of LV contraction. Using it as a reference, we were able to obtain more accurate quantitative data about LV regional wall motion.