Intracardiac M-mode echocardiography for continuous left ventricular monitoring: method and potential application.

Because no accurate and readily applied method exists for continuous recording of left ventricular cavity dimensions and wall motion in man, we designed a catheter-mounted echocardiographic probe. The purpose of this report is to describe the instrumentation, technique, limitations, complications and preliminary observations employing the probe in humans. The echo transducer built into a cardiac allowed positioning in the right heart under fluoroscopy. The echo signals permitted continuous left ventricular cavity measurements at rest and during maneuvers. Our results suggest that intracardiac echo may be able to provide clear definition of motion patterns of the mitral valve and left ventricular walls. The ultrasonic catheter is an instrument that potentially offers a new technique for continuous monitoring of left ventricular size and motion.     

Chaotic echo motion in the left ventricular cavity. Visualization of ruptured chordae tendineae of the mitral valve by real-time two-dimensional echocardiography

The aim of the present study is to perform a detailed analysis of the spot echoes which show chaotic motion of the left ventricular cavity of patients with ruptured chordae tendineae. The subjects were 12 patients with surgically documented ruptured chordae tendineae. They were carefully examined preoperatively by real-time two-dimensional echocardiography with a commercially available wide-angle phased array system (Toshiba SSH-11A). An abnormal moving spot echo was often seen instantaneously in the left ventricle. Its motion was chaotic, and it moved both longitudinally and laterally. Lateral movements were seen in 10 of the 12 subjects and were not found in any of 10 controls. The site of this echo in the left ventricle was identical with the site of the rupture of the mitral chordae confirmed during surgery. Therefore, it was concluded that the spot echo with chaotic motion represents a direct visualization of ruptured chordae. This chaotic motion is considered to be a useful clue in diagnosis. The lateral component (left to right) of the movement is especially important. However, one must carefully examine the left ventricular cavity with moving pictures over a period of many heart beats in order to detect these chaotic movements of spot echoes.     

Diagnostic Value of Exercise‐Induced ST‐Segment Elevation in Q‐Wave Leads. After Recent Myocardial Infarction

Background: Exercise‐induced ST‐segment elevation in an infarct territory with abnormal Q waves is a known marker for more severe left ventricular wall‐motion abnormalities. However, it is reported, that exercise‐induced ST‐segment elevation in infarct leads may indicate residual viability in the intarctregion. The aim of the study was to test whether exercise‐induced ST‐segment elevation is related to left ventricular (LV) dysfunction or to persistent viability in patients with previous myocardial infarction (MI). Methods: 145 consecutive patients (119 men, 26 women, age 58 ± 11 years) 2–3 weeks after Q‐wave Ml but without ST elevation at rest ECG were enrolled in the study. All patients underwent a target heart rate or symptom‐limited exercise testing (ET) with Bruce protocol. Exercise‐induced ST‐segment elevation < 1 mm above the baseline ST segment level (80 ms after J point) in more than 1 ECG lead with Q wave was considered to be significant. Patients were divided in two groups according to ET results: group I, 25 patients with significant exercise‐induced ST‐segment elevation and group II, 120 patients without exercise‐induced ST‐segment elevation. All patients underwent rest ECHO and low dose dobutamine stress echo (LOSE) within 7 days after ET. LV function was estimated using ejection fraction (EF). Results: More severe LV dysfunction was observed in patients from group 1 (EF 31 ± 8.16% vs EF 45 ± 10.3%). Myocardial viability (defined as an improvement of regional systolic wall thickening in the regions with resting regional wall‐motion abnormalities during LOSE 5 to 15 g/kg/min was recognized in 8 patients (32%) in group I and 31 patients (25.8%) in group II. There was no relation between exercise‐induced ST‐segment elevation and myocardial viability (chi‐square test: 2,809; NS). Conclusions: Exercise‐induced ST‐segment elevation in most cases is associated with left ventricular dysfunction. Patients with exercise‐induced ST‐segment elevation have a lower EF than those without and greater severity of resting wall‐motion abnormalities. Our results suggest that exercise‐induced ST‐segment elevation is not related to residual myocardial viability.     

Transseptal left heart catheterization a 50-year odyssey

Development in the 1950s of the transseptal technique for left heart catheterization is described. Initial studies in animals and human cadavers were followed up by left atrial puncture with measurements of left atrial and left ventricular (LV) pressure (the latter using a small plastic catheter) in patients with cardiac disease. Many such procedures were performed safely without complications. Subsequent modification of the original technique for percutaneous catheter insertion allowed placement of a larger taper-tipped catheter in the LV chamber for selective LV angiography. Early clinical research studies at the National Heart Institute were performed using the transseptal method; these included investigation of the effects of increasing afterload on the normal and failing left ventricle by means of a graded angiotensin infusion to induce a progressive increase in aortic pressure. A marked decrease in the stroke volume occurred with increased afterload in the failing heart. This finding later led to the concept of afterload mismatch with limited pre-load reserve. Another early transseptal catheterization study in which measurements of LV pressure were made at different locations within the left ventricle as well as in the left atrium confirmed the presence of cavity obliteration in some patients and true obstruction in the LV outflow tract in many others. In addition, left ventriculography showed that obstruction was caused by abnormal anterior position during systole of the anterior mitral valve leaflet. With growing acceptance of retrograde catheterization of the left ventricle, the use of the transseptal technique for diagnostic purposes declined. However, in recent years, substantial renewed application of the transseptal method has occurred for special diagnostic and therapeutic purposes, including balloon valvuloplasties and electrophysiologic ablation procedures within the left heart.     

Smoke-like echo in the left atrial cavity in mitral valve disease: its features and significance

In some patients with mitral stenosis, a smoke-like echo is observed in the left atrial cavity. The present study in 116 consecutive patients with rheumatic mitral valve disease investigated the echocardiographic features and clinical significance of this echo. The smoke-like echo is characterized by the following echocardiographic features: 1) it is composed of numerous microechoes; 2) it curls up slowly in the enlarged left atrial cavity; and 3) it vanishes as soon as it pours into the ventricular cavity. Hemostasis in the left atrial cavity was considered to be an important underlying condition for development of the echo. Hemorheologic conditions indicated that the shear rate of blood flow in the left atrial cavity was calculated to be low enough for the development of red blood cell aggregation. These conditions suggest that the source of the smoke-like echo might be aggregated cells due to hemostasis in the left atrial cavity. Left atrial thrombi were detected in many patients who had this echo in the left atrial cavity. Although it has not been conclusively determined that the presence of the smoke-like echo is a necessary condition for thrombus formation, this echo appears to be closely related to thrombus formation in the left atrial cavity. It is concluded that the presence of this echo indicates severe left atrial hemostasis and is a warning for thrombus formation.     

Anterior left ventricular wall echoes in coronary artery disease. Linear scanning with a single element transducer

The feasibility and usefulness of obtaining anterior left ventricular wall echoes were studied using a linear cardiac scan with a single element tranducer and M mode recordings. One hundred four patients were examined: 50 with acute myocardial infarction and 54 who underwent left ventricular angiography and coronary cineangiography for evaluation of chest pain. Of the 54 patients with cardiac catheterization studies, 11 had no evidence of cardiac disease, 42 had 50 percent or greater obstruction in one or more of the three major coronary arteries and one had aortic insufficiency. Anterior left ventricular wall echo motion toward the transducer or absence of motion during ejection was called abnormal, and motion away from the transducer during ejection was interpreted as normal. Abnormal motion was seen in four of four patients with an isolated lesion of the anterior descending coronary artery, in one of three with an isolated lesion of the right coronary artery and in neither of two with an isolated lesion of the left circumflex artery. Of the 20 patients with obstructive coronary artery disease by arteriography and abnormal left ventricular wall echo motion, 18 had obstruction of the left anterior descending artery with or without other disease. Correlation of the anterior left ventricular echograms with the left ventricular angiograms was poor, with agreement in only 66 percent (33 of 50) of cases. Twenty-five of 26 patients with acute infarction and abnormal anterior left ventricular wall echo motion had electrocardiographic changes indicative of anterior or lateral wall infarction, or both. Twenty-five of 34 patients with electrocardiographic changes indicative of anterior wall infarction had an abnormal anterior wall motion echo. This study shows that obtaining the anterior left ventricular wall echo is feasible and useful in patients with coronary artery disease since abnormal anterior left ventricular wall motion is closely associated with anterior wall ischemia or infarction in these patients.     

Relation of regional echo amplitude to left ventricular function and the electrocardiogram in left ventricular hypertrophy

In order to determine the relation between three manifestations of left ventricular hypertrophy--ST-T wave changes on the electrocardiogram, diastolic disturbances, and increased myocardial echo intensity--M mode and cross sectional echocardiograms were recorded in 12 normal subjects, 15 athletes, 16 patients with hypertrophic cardiomyopathy, and 42 patients with secondary left ventricular hypertrophy due to aortic stenosis (20), severe essential hypertension (8), coarctation (7), or subaortic stenosis (7). M mode echocardiograms were digitised and cross sectional echocardiograms were analysed for regional echo intensity. In patients with hypertrophy regional echo amplitude was significantly increased in mid and basal septum and posterior left ventricular wall. Patients with increased echo amplitude in any region showed a higher incidence of ST-T wave abnormalities than those without and of diastolic abnormalities--including prolongation of isovolumic relaxation time, delay in mitral valve opening with respect to minimum cavity dimension, and a reduction in peak rate of posterior wall thinning and dimension increase. There was a significant rank order correlation between median pixel count and these diastolic abnormalities. No significant differences were demonstrable in these relations between the diagnostic groups. By contrast, electrocardiographic findings, diastolic function, and pixel count were uniformly normal in athletes, although the increase in left ventricular mass was similar to that in the patients. Thus an increase in left ventricular mass alone is not responsible for repolarisation or wall motion abnormalities occurring in pathological left ventricular hypertrophy. These latter changes are, however, strongly associated with the change in myocardial properties detected as an increase in echo intensity and may be due to increased interstitial fibrosis.     

Relation of regional echo amplitude to left ventricular function and the electrocardiogram in left ventricular hypertrophy.

In order to determine the relation between three manifestations of left ventricular hypertrophy--ST-T wave changes on the electrocardiogram, diastolic disturbances, and increased myocardial echo intensity--M mode and cross sectional echocardiograms were recorded in 12 normal subjects, 15 athletes, 16 patients with hypertrophic cardiomyopathy, and 42 patients with secondary left ventricular hypertrophy due to aortic stenosis (20), severe essential hypertension (8), coarctation (7), or subaortic stenosis (7). M mode echocardiograms were digitised and cross sectional echocardiograms were analysed for regional echo intensity. In patients with hypertrophy regional echo amplitude was significantly increased in mid and basal septum and posterior left ventricular wall. Patients with increased echo amplitude in any region showed a higher incidence of ST-T wave abnormalities than those without and of diastolic abnormalities--including prolongation of isovolumic relaxation time, delay in mitral valve opening with respect to minimum cavity dimension, and a reduction in peak rate of posterior wall thinning and dimension increase. There was a significant rank order correlation between median pixel count and these diastolic abnormalities. No significant differences were demonstrable in these relations between the diagnostic groups. By contrast, electrocardiographic findings, diastolic function, and pixel count were uniformly normal in athletes, although the increase in left ventricular mass was similar to that in the patients. Thus an increase in left ventricular mass alone is not responsible for repolarisation or wall motion abnormalities occurring in pathological left ventricular hypertrophy. These latter changes are, however, strongly associated with the change in myocardial properties detected as an increase in echo intensity and may be due to increased interstitial fibrosis.     

Accuracy and usefulness of ultraportable hand-carried echocardiography system

OBJECTIVES: The diagnostic accuracy and usefulness of an ultraportable hand-carried echocardiography system were investigated for assessing ventricular systolic function and severity of mitral valvular regurgitation. METHODS: The study population consisted of 77 consecutive patients (47 men, 30 women, mean age 63 +/- 15 years). Left ventricular end-diastolic dimension, left ventricular end-systolic dimension and left ventricular ejection fraction were measured using the hand-carried echo system and the data were compared with measurements by the conventional echocardiography system using simple linear regression analysis. Left ventricular wall motion was compared between the systems using a 16-segment model recommended by the American Society of Echocardiography. Severity of mitral regurgitation was assessed by the distance of the regurgitant signal in the left atrium. RESULTS: Left ventricular end-diastolic dimension, left ventricular end-systolic dimension and left ventricular ejection fraction showed good correlations between hand-carried and conventional echo systems (r = 0.94, 0.91 and 0.81, respectively; each p < 0.0001). The accuracy for assessing left ventricular wall motion was 94% (449 of 480 segments). The echo systems also showed the same degree of diagnostic accuracy for severity of mitral regurgitation. CONCLUSIONS: The hand-carried echo system provides accurate assessment of left ventricular function and mitral regurgitation simular to conventional echo machines.     

Left ventricular performance assessed by radionuclide angiocardiography and echocardiography in patients with previous myocardial infarction.

In 61 patients (77 studies) who had a transmural myocardial infarction, we compared the left ventricular ejection fraction by echocardiography with the ejection fraction determined by a computerized radioisotope technique that makes no assumptions regarding left ventricular geometry. In 31 studies of 26 patients with normal left ventricular wall motion by videotracking and normal left heart size, ejection fraction averaged 0.57 +/- 0.09 (SD) by ultrasound and 0.62 +/- 0.10 by the isotope method. Measurements of ejection fraction by both techniques correlated well (r = 0.86) and there was complete separation between patients with normal and reduced ejection fraction. In 46 studies of 35 patients in whom left ventricular wall motion abnormalities were recorded by videotracking, ejection fraction by the isotope method averaged 0.46 +/- 0.08, while average echo ejection fraction was 0.62 +/- 0.12. The correlation between the ultrasound and isotope methods in these 46 studies was poor (r = 0.33) and in 28 studies measurement of the ejection fraction by the two techniques was discordant. In 26 of the 27 studies where there was a reduced ejection fraction by the isotope method and a normal ejection fraction by echo, the dyssynergy involved the anterolateral left ventricular wall. These data indicate that echocardiographic measurements frequently overestimate left ventricular performance in patients with previous myocardial infarction associated with anterolateral wall motion disorders.     

Three-dimensional echocardiographic measurement of left ventricular mass: Comparison with magnetic resonance imaging and two-dimensional echocardiographic determinations in man

This study was performed to compare a novel three-dimensional echocardiography (3DE) system to clinical two-dimensional echocardiography (2DE) and magnetic resonance imaging (MRI) for determination of left ventricular mass (LVM) in humans. LVM is an independent predictor of cardiac morbidity and mortality. Echocardiography is the most widely used clinical method for assessment of LVM, as it is non-invasive, portable and relatively inexpensive. However, when measuring LVM, 2DE is limited by assumptions about ventricular shape which do not affect 3D echo. Methods: A total of 25 unselected patients underwent 3DE, 2DE and MRI. Three-dimensional echo used a magnetic scanhead tracker allowing unrestricted selection and combination of images from multiple acoustic windows. Mass by quantitative 2DE was assessed using seven different geometric formulas. Results: LVM by MRI ranged from 91 to 316 g. There was excellent agreement between 3DE and MRI (r = 0.99, SEE = 6.9 g). Quantitative 2D methods correlated well with but underestimated MRI (r = 0.84–0.92) with SEEs over threefold greater (22.5–30.8 g). Interobserver variation was 7.6% for 3DE vs. 17.7% for 2DE. Conclusions: LVM in humans can be measured accurately, relative to MRI, by transthoracic 3D echo using magnetic tracking. Compared to 2D echo, 3D echocardiography significantly improves accuracy and reproducibility.     

Continuous measurement of left ventricular volume in animals and humans by conductance catheter

An eight-electrode conductance catheter previously developed by us and used to determine stroke volume in dogs was applied in human beings and dogs to measure absolute left ventricular volume quantitatively. For calibration we developed the formula V(t) = (1/alpha)(L2/sigma b)G(t) - Vc, where V(t) is time-varying left ventricular volume, alpha is a dimensionless constant, L is the electrode separation, sigma b is the conductivity of blood obtained by a sampling cuvette, and G(t) is the measured conductance within the left ventricular cavity. Vc is a correction term caused by the parallel conductance of structures surrounding the cavity and is measured in two ways. The first method, applicable in the anesthetized animal, consists of temporary reduction of volume to zero by suction. The second method uses a transient change in sigma b by injection of a small bolus of hypertonic saline (dogs) or 10 ml of cold glucose (humans) into the pulmonary artery. The validity of the formula was previously established for the isolated postmortem canine heart. The predicted linearity, slope constant alpha, and accuracy of Vc for the left ventricle in vivo were investigated by comparing the conductance volume data with results from independent methods: electromagnetic blood flow measurement for stroke volume and indicator dilution technique for ejection fraction (dogs), thermal dilution for cardiac output (12 patients), and single-plane cineventriculography for V(t) (five patients). In all comparisons, linear regression showed high correlation (from r = .82 [n = 46] to r = .988 [n = 20]) while alpha, with one exception, ranged from 0.75 to 1.07 and the error in Vc ranged from 0.5% to 16.5% (mean 7%). After positioning of the catheter, no arrhythmias were observed. It is concluded that the conductance catheter provides a reliable and simple method to measure left ventricular volume, giving an on-line, time-varying signal that is easily calibrated. Together with left ventricular pressure obtained through the catheter lumen, the instrument may be used for instantaneous display of pressure-volume loops to facilitate assessment of left ventricular pump performance.     

Mitral regurgitation in hypertrophic cardiomyopathy. Non-invasive study by two dimensional Doppler echocardiography

Mitral regurgitation and its haemodynamic features were investigated non-invasively in cases of hypertrophic cardiomyopathy by means of two dimensional Doppler echocardiography. There were 28 patients, 14 of whom showed systolic anterior motion (SAM) of the mitral echo; the other 14 did not. The following results were obtained. (1) Mitral regurgitation was detected by the Doppler technique in all cases with systolic anterior motion of the mitral echo and in half of those without it. (2) Doppler signals of mitral regurgitation started immediately after the first heart sound. (3) Mitral regurgitant flow was often distributed from the entire mitral orifice over the entire or the posterior half of the left atrium in the cases with systolic anterior motion. In the cases without systolic anterior motion the regurgitation was usually localised near the mitral orifice. These features differ from those of regurgitation usually seen in rheumatic mitral valve disease and idiopathic mitral valve prolapse. (4) The Doppler technique and left ventriculography were equally efficient in detecting mitral regurgitation. (5) The early systolic component of the murmur of hypertrophic myopathy is considered to result in the main from concomitant mitral regurgitation, but not from turbulent blood flow in the left ventricular outflow tract, so that in cases with mitral regurgitation as a complication, mitral regurgitation may also contribute to the development of the midsystolic portion of the systolic murmur, while the main origin of this portion of the murmur is the left ventricular outflow obstruction.     

Mitral regurgitation in hypertrophic cardiomyopathy. Non-invasive study by two dimensional Doppler echocardiography.

Mitral regurgitation and its haemodynamic features were investigated non-invasively in cases of hypertrophic cardiomyopathy by means of two dimensional Doppler echocardiography. There were 28 patients, 14 of whom showed systolic anterior motion (SAM) of the mitral echo; the other 14 did not. The following results were obtained. (1) Mitral regurgitation was detected by the Doppler technique in all cases with systolic anterior motion of the mitral echo and in half of those without it. (2) Doppler signals of mitral regurgitation started immediately after the first heart sound. (3) Mitral regurgitant flow was often distributed from the entire mitral orifice over the entire or the posterior half of the left atrium in the cases with systolic anterior motion. In the cases without systolic anterior motion the regurgitation was usually localised near the mitral orifice. These features differ from those of regurgitation usually seen in rheumatic mitral valve disease and idiopathic mitral valve prolapse. (4) The Doppler technique and left ventriculography were equally efficient in detecting mitral regurgitation. (5) The early systolic component of the murmur of hypertrophic myopathy is considered to result in the main from concomitant mitral regurgitation, but not from turbulent blood flow in the left ventricular outflow tract, so that in cases with mitral regurgitation as a complication, mitral regurgitation may also contribute to the development of the midsystolic portion of the systolic murmur, while the main origin of this portion of the murmur is the left ventricular outflow obstruction.     

Computer analysis of cross sectional echocardiogram for quantitative evaluation of left ventricular asynergy in myocardial infarction.

Left ventricular asynergy in myocardial infarction was assessed quantitatively by computer analysis of the cross sectional echocardiogram. Short axis cross sectional images of the left ventricle at the levels of the mitral valve, papillary muscle, and apex were recorded by a phased array sector scanner in 30 patients with healed myocardial infarction and 15 normal controls. Endocardial and epicardial short axis images of the left ventricle were transferred from video tape to a minicomputer through the interface circuits, then digitised and processed automatically by a minicomputer. Automatic edge detection of the endocardial and epicardial wall was performed by applying sequential steps including smoothing, second derivative technique, dynamic thresholding, and approximation of boundaries by a spline curve. To quantify regional wall motion, the short axis cross sectional left ventricular wall of each level was divided into eight octants with eight axes at 45 degrees angles from the initial standard axis which was constructed from the geometric centre of the end diastolic left ventricular cavity to the posterior end of the right side of the interventricular septum. Segmental hemiaxis, segmental area, segmental wall thickness, and those changes during cardiac cycle were measured and calculated in each segment automatically by a computer. Regional contractility of the left ventricle was evaluated by percentage systolic changes of the segmental hemiaxis, area, and wall thickness. These values were significantly reduced in the infarcted left ventricular wall as defined by left ventriculography and electrocardiography. Moreover, percentage hemiaxis changes obtained by quantitative left ventriculography described by Herman and colleagues correlated well with those using our analytical method of cross sectional echocardiography in the corresponding segments. The geometric centre of the left ventricular cavity determined by the computer moved slightly towards the anterior wall during systole in normal subjects, possibly reflecting the anterior swinging motion of the heart. The geometric centre of the left ventricular cavity in myocardial infarction moved towards the infarcted wall, showing that the floating reference system was inferior to the fixed reference system for the quantification of abnormal wall motion in myocardial infarction. In conclusion, a computer analysis of the short axis cross sectional echocardiogram of the left ventricle using the fixed reference system has shown its ability to evaluate left ventricular contraction abnormalities, especially systolic wall thickening, which is relatively free of arbitrary interpretation of the wall motion caused by the anterior swinging motion of the heart.     

Intracardiac echocardiography off piste? Closure of the left atrial appendage using ICE and local anesthesia

Left atrial appendage (LAA) occlusion is increasingly accepted to reduce the risk of stroke in patients with atrial arrhythmia who are unsuitable for routine anticoagulation. It is generally performed under general anesthesia, guided by transoesophageal echocardiography with accurate imaging being essential for correct deployment of the device. We present a case where LAA occlusion was done under local anesthesia in a high‐anesthetic risk patient, using novel placement of an intracardiac echo probe via a Mullins sheath in the right ventricular outflow tract and pulmonary artery. This allowed accurate visualization of device deployment in the LAA. This technique may increase the spectrum of patients who may benefit from the procedure and decrease procedure time, fluoroscopy, and procedure‐related morbidity. © 2010 Wiley‐Liss, Inc.     

Is angiographic ventriculography necessary for the assessment of ischemic patients?

A total of 53 patients with a provisional diagnosis of ischemic heart disease and without any clinical evidence of valvular, congenital, or primary muscle heart disease were studied by echocardiography and biplane left ventricular cineangiography. For angiographic ejection fraction analysis, a program developed in our department for use on an Apple Macintosh computer interfaced to a digitizing tablet was employed. Echocardiographic outlines of systolic and diastolic images were traced with a digitizing system on the screen and ejection fractions were calculated by a program incorporated in the echo machine. Good echo windows allowing ejection fraction calculations were present in 35 patients. There was a good correlation between angiographic and echocardiographic ejection fraction (r = 0.7, SEE = 0.09), and wall motion assessment revealed no significant discrepancies between the two image modalities. The remaining 18 patients had poor echo windows, preventing accurate echocardiographic determination of the ejection fraction. However, limited assessment of left ventricular size and wall motion was possible in all patients and allowed the identification of those who had impaired left ventricular function as judged by angiography (angiographic ejection fraction < 35%). We conclude that even in patients with poor echo windows echocardiographic assessment of left ventricular function provides clinical information similar to angiography which should not be considered mandatory for the investigation of ordinary ischemic patients.     

Computer analysis of cross sectional echocardiogram for quantitative evaluation of left ventricular asynergy in myocardial infarction

Left ventricular asynergy in myocardial infarction was assessed quantitatively by computer analysis of the cross sectional echocardiogram. Short axis cross sectional images of the left ventricle at the levels of the mitral valve, papillary muscle, and apex were recorded by a phased array sector scanner in 30 patients with healed myocardial infarction and 15 normal controls. Endocardial and epicardial short axis images of the left ventricle were transferred from video tape to a minicomputer through the interface circuits, then digitised and processed automatically by a minicomputer. Automatic edge detection of the endocardial and epicardial wall was performed by applying sequential steps including smoothing, second derivative technique, dynamic thresholding, and approximation of boundaries by a spline curve. To quantify regional wall motion, the short axis cross sectional left ventricular wall of each level was divided into eight octants with eight axes at 45 degrees angles from the initial standard axis which was constructed from the geometric centre of the end diastolic left ventricular cavity to the posterior end of the right side of the interventricular septum. Segmental hemiaxis, segmental area, segmental wall thickness, and those changes during cardiac cycle were measured and calculated in each segment automatically by a computer. Regional contractility of the left ventricle was evaluated by percentage systolic changes of the segmental hemiaxis, area, and wall thickness. These values were significantly reduced in the infarcted left ventricular wall as defined by left ventriculography and electrocardiography. Moreover, percentage hemiaxis changes obtained by quantitative left ventriculography described by Herman and colleagues correlated well with those using our analytical method of cross sectional echocardiography in the corresponding segments. The geometric centre of the left ventricular cavity determined by the computer moved slightly towards the anterior wall during systole in normal subjects, possibly reflecting the anterior swinging motion of the heart. The geometric centre of the left ventricular cavity in myocardial infarction moved towards the infarcted wall, showing that the floating reference system was inferior to the fixed reference system for the quantification of abnormal wall motion in myocardial infarction. In conclusion, a computer analysis of the short axis cross sectional echocardiogram of the left ventricle using the fixed reference system has shown its ability to evaluate left ventricular contraction abnormalities, especially systolic wall thickening, which is relatively free of arbitrary interpretation of the wall motion caused by the anterior swinging motion of the heart.     

Stimulated Acoustic Emission Nonbackscatter Contrast Effect of Microbubbles Seen with Harmonic Power Doppler Imaging

Transient imaging has been introduced to enhance the signal intensities when using echo contrast agents. However, this phenomenon is not clearly understood. To evaluate the mechanisms of this phenomenon, isolated pig hearts were investigated with different echo imaging techniques in the beating, working heart as well as in an asystolic state without any motion of the heart. The hearts of five German farm pigs (21 ± 2.5 kg) were surgically explanted and inserted in an artificial circulation providing physiological flow and pressures. Levovist in the dosage of 0.05–0.3 g was injected into the left atrium and contrast effects evaluated in the left ventricular (LV) cavity and in the myocardium with an ultrasound imager (ATL, HDI 3000) equipped with a prototype software for harmonic imaging. Harmonic B-scans and power Doppler registrations were performed with continuous and intermittent recordings (ECG triggered at end-systole) in the beating heart and using an external trigger in the asystolic heart in which perfusion was interrupted for 20 seconds. In the beating pig heart, transient harmonic power Doppler imaging provided intensive opacification of the LV cavity and visible myocardial uptake when ECG triggering was performed. In the asystolic pig heart, with uninterrupted perfusion, both triggered and nontriggered registrations showed contrast signals in the LV cavity and in the myocardium. These findings cannot be explained with the known physics of ultrasound contrast media. Stimulated acoustic emission occurring during disintegration of the microbubbles in the acoustic field would explain this phenomenon, which has not yet been described for Levovist.     

Dedicated radial ventriculography pigtail catheter

A new dedicated cardiac ventriculography catheter was specifically designed for radial and upper arm arterial access approach. Two catheter configurations have been developed to facilitate retrograde crossing of the aortic valve and to conform to various subclavian, ascending aortic and left ventricular anatomies. The “short” dedicated radial ventriculography catheter is suited for horizontal ascending aortas, obese body habitus, short stature and small ventricular cavities. The “long” dedicated radial ventriculography catheter is suited for vertical ascending aortas, thin body habitus, tall stature and larger ventricular cavities. This new design allows for improved performance, faster and simpler insertion in the left ventricle which can reduce procedure time, radiation exposure and propensity for radial artery spasm due to excessive catheter manipulation. Two different catheter configurations allow for optimal catheter selection in a broad range of patient anatomies. The catheter is exceptionally stable during contrast power injection and provides equivalent cavity opacification to traditional femoral ventriculography catheter designs.