Gerson S. Lichtenberg

Superiority of visual versus computerized echocardiographic estimation of radionuclide left ventricular ejection fraction

An optimal method for determining left ventricular ejection fraction (LVEF) by echocardiography should be rapid, reliable, and widely applicable in order to be utilized routinely in a busy clinical laboratory. Most methods reported in the literature are reliable in selected, high-quality echocardiograms. Most require off-line computer analysis and are time-consuming and poorly suited to the routine of a busy laboratory. We compared in a blinded manner several echocardiographic methods of LVEF determination with the ejection fraction obtained by equilibrium radionuclide angiography (ERNA) in 44 patients unselected for image quality. Echocardiographic methods included: [1] cubed M-mode formula; [2] Teichholz M-mode formula; [3] subjective estimation of LVEF from two-dimensional echocardiographic videotape; [4] area-length method in one four-chamber view; [5] average of area-length method in three four-chamber views; [6] average of area-length method in four-chamber and two-chamber views (one beat each); [7] subjective estimation from stored videoloop of four-chamber and two-chamber view. In 30 cases M-mode tracings were available for analysis. In only 23 of the 44 patients were the apical views suitable for quantitative analysis. The ERNA ejection fraction was 44 +/- 17% (mean +/- 1 SD). The best echocardiographic correlation with ERNA ejection fraction in each patient subgroup studied was obtained by method 3. We concluded that subjective analysis of the videotaped study by an experienced cardiologist/echocardiographer provided the best estimation of ERNA ejection fraction. More time-consuming and costly computer techniques yielded a worse estimate.

Intravenous contrast echocardiography with use of sonicated albumin in humans: Systolic disappearance of left ventricular contrast after transpulmonary transmission☆

The transmission of echocardiographic contrast medium and the cyclic changes in left ventricular videodensity during transpulmonary contrast echocardiography were investigated in nine adult volunteers with the use of intravenous injections of sonicated albumin (microbubble size 5.2 +/- 2.6 microns). Right and left ventricular and myocardial contrast were quantitated by videodensitometric analysis. The injections caused no symptoms, and no hemodynamic or electrocardiographic changes were observed. All injections resulted in right ventricular contrast. Mean peak right ventricular videodensity was 75 +/- 48 at end-diastole and 61 +/- 36 gray scale U/pixel at end-systole (p less than 0.05). Seventy-eight percent of injections resulted in left ventricular contrast with a mean peak videodensity of 21 +/- 33 gray scale U/pixel. Early systole was associated with a rapid decrease in left ventricular contrast intensity with near total disappearance of contrast by end-systole (from 23 +/- 33 and 17 +/- 23 U/pixel at end-diastole to 6 +/- 10 and 3 +/- 2 at end-systole at the left ventricular base and apex, respectively; p less than 0.05). None of the injections resulted in myocardial contrast enhancement by visual or quantitative analysis. Thus, left ventricular contrast echocardiography can be achieved after intravenous injections of sonicated albumin. Transpulmonary left ventricular contrast echocardiography is associated with near total disappearance of contrast during systole. This may be secondary to the destruction of microbubbles by the high left ventricular systolic pressure. These findings may help explain the limited success of this technique thus far for myocardial perfusion imaging.

Myocardial perfusion imaging by contrast echocardiography with use of intracoronary sonicated albumin in humans.

Sonicated albumin has been proposed as a near ideal echocardiographic contrast agent with little myocardial toxicity or hemodynamic effect. Its use has not yet been reported in humans, partly because of difficulties in preparation. With use of the newly modified sonication method, 10 ml of 5% albumin was sonicated for 75 s with a 5.0 ml slow infusion of air. This resulted in microbubbles with a mean diameter (+/- SD) of 5 +/- microns). Fourteen patients undergoing routine coronary angiography were studied. One patient had normal coronary arteries; the other 13 had significant coronary artery disease. In a subgroup of nine patients, sonicated albumin and sonicated diatrizoate meglumine sodium (microbubble diameter 9 +/- 3 microns) were injected several minutes apart, using the same technique. Videodensity-time curves were obtained from a region of interest in the myocardium. Corrected peak contrast intensity (baseline contrast intensity subtracted from peak contrast intensity, gray scale U/pixel) for sonicated albumin and for sonicated diatrizoate meglumine sodium was 51 +/- 26 and 52 +/- 19, respectively (p = 0.89). Washout half-time (T1/2) for the two agents was 5.5 +/- 4.5 and 16.0 +/- 12.2 s, respectively (p = 0.01). One patient with unstable angina experienced transient chest pain after repeated albumin injections. No electrocardiographic changes, blood pressure changes or wall motion abnormalities were observed. Administered by intracoronary injection, sonicated 5% albumin is a safe and effective echocardiographic contrast agent for myocardial perfusion imaging, yielding excellent myocardial contrast with physiologic washout time.

Quantitative assessment of the immediate results of coronary angioplasty by myocardial contrast echocardiography.

A low pressure gradient across the residual lesion and a minimal percent residual stenosis are markers of a successful coronary angioplasty. A more physiologic method of assessing the results of coronary angioplasty would involve assessment of myocardial perfusion in the affected coronary bed. Contrast two-dimensional echocardiography provides information about regional myocardial perfusion. To assess the correlation between pre- to postcoronary angioplasty changes in gradient or percent stenosis and the increase in peak contrast intensity, 23 consecutive patients were studied during coronary angioplasty. In 19 of the 23 patients, the coronary angioplasty was successful and in 15 (79%) of the 19, an adequate echocardiographic study was obtained. Mild and transient side effects of echo contrast were observed in 3 of the 15 patients. The gradient across the residual lesions decreased from 52 +/- 12 to 11 +/- 4 mm Hg (mean +/- SD), the diameter of the stenotic lesion decreased from 89 +/- 10 to 25 +/- 16% and corrected peak contrast intensity (peak contrast - baseline contrast in gray level U/pixel) increased from 15 +/- 16 to 50 +/- 26. All these differences were significant at the p less than 0.001 level. Corrected peak contrast intensity correlated exponentially with the decrease in pressure gradient (r = 0.82, p less than 0.001). The correlation curve had a greater increase in peak contrast intensity at gradient decreases greater than 45 mm Hg. Corrected peak contrast intensity did not correlate with decrease in diameter of the stenotic lesion (r = 0.19).

Exercise doppler echocardiography in patients with mitral prosthetic valves

Submaximal supine exercise was done by 17 patients with mitral prostheses. Eleven had Björk-Shiley (BS) and six had Starr-Edwards (SE) valves. In 15 patients with normally functioning prostheses, valve area at rest was 2.4 +/- 0.25 cm2 in the BS patients and 1.8 +/- 0.35 cm2 in the SE group (p less than 0.01). In the SE group, peak and mean gradients increased from 8 +/- 1 and 5 +/- 1 mm Hg, respectively, at rest to 22 +/- 5 and 13 +/- 4 mm Hg at peak exercise (mean +/- 1 SD). In the BS group, peak and mean gradients increased from 10 +/- 3 and 5 +/- 2 mm Hg, respectively, at rest to 16 +/- 3 and 10 +/- 3 mm Hg at peak exercise. Peak pressure gradient at peak exercise and the increase in peak gradient with exercise (exercise-resting gradient) were significantly higher in the SE group (p less than 0.05). By plotting the heart rate versus the transmitral gradient during the recovery period, a heart rate-gradient curve was obtained for each type of prosthesis. Doppler echocardiography with moderate supine exercise can be performed in most patients with mechanical prosthesis. Hemodynamic properties (the occlusive character of the SE prosthesis) were brought out by exercise. Doppler echocardiographic measurements during exercise can provide important information, particularly in patients with borderline measurements at rest.

Blunt Trauma Causing Delayed Cardiac Tamponade Echocardiographic Diagnosis

A 17-year-old patient suffered multiple trauma from a motor vehicle accident that involved blunt chest trauma. During the initial hospitalization and laparotomy for abdominal injuries, the cardiac silhouette remained normal on chest roentgenogram and there were no signs of pericardial tamponade. He went home and returned 2 weeks later with a 3 to 4-day history of increasing dyspnea and findings of cardiac tamponade. A loculated, blood-filled mass was found by echocardiography and at surgery, compressing the right heart. This type of delayed pericardial tamponade after blunt trauma has not previously been described.

Myocardial Perfusion Studies by Contrast Echocardiography

Determination of regional myocardial blood flow may provide clinically valuable information about ischemia, risk area, and the effect of angioplastic, surgical, and pharmacologic interventions. Contrast echocardiography, with use of prepared microbubbles of 4 to 8 microns size, graphically demonstrates perfusion characteristics in the catheterization laboratory. Analysis and interpretation of this data and the creation of contrast materials that will demonstrate myocardial perfusion after intravenous injection are some of the next challenges in these techniques.

Spontaneous Echocardiographic Contrast

In this issue, Galanti and associates’ present an interesting observation of spontaneous contrast in the hearts of highly trained athletes. This report is significant because all other descriptions of increased echogenicity having bloodlike motion have been associated with intravenous invasion, low-flow states, or placement of prosthetic valves. Galanti and coworkers offer the first report of spontaneous contrast in the normal, although hardly average, left ventricle. The authors discuss two possible explanations for the observed spontaneous contrast: microbubbles and blood cell aggregate formation. We believe that they overemphasize the likelihood of microbubble production in this setting. The argument for a microbubble etiology for contrast is based on work by Kort and Kronzon,2 who described blood passing through a stenotic orifice at high velocities. This work is invoked by Galanti and colleagues to suggest that the spontaneous contrast in the athletes’ hearts might be due to microbubbles. Kort and Kronzon’s fluid dynamic situation, however, appears to be quite different from the decreased flow at the apex of the left ventricle occurring during diastole when the spontaneous contrast was observed. The slow heart rate of the ath-