James C. Dillon

An echocardiographic index for separation of right ventricular volume and pressure overload

Abnormal motion of the interventricular septum has been described as an echocardiographic feature of both right ventricular volume and pressure overload. To determine if two-dimensional echocardiography can separate these two entities and distinguish them from normal, geometry and motion of the interventricular septum in short-axis views of the left ventricle were evaluated in 12 normal subjects and 35 patients undergoing cardiac catheterization. Thirteen of the 35 patients had uncomplicated atrial septal defect with associated right ventricular volume overload, but no elevation in pulmonary artery pressure. The 22 remaining patients had a pulmonary artery systolic pressure greater than 40 mm Hg and, thus, constituted the group with right ventricular pressure overload. An eccentricity index, defined as the ratio of the length of two perpendicular minor-axis diameters, one of which bisected and was perpendicular to the interventricular septum, was obtained at end-systole and end-diastole. In all normal subjects, the eccentricity index at both end-systole and end-diastole was essentially 1.0, as would be expected if the left ventricular cavity was circular in the short-axis view. In patients with right ventricular volume overload, the eccentricity index was approximately 1.0 at end-systole, but was significantly increased at end-diastole (mean eccentricity index = 1.26 +/- 0.12) (p less than 0.001). In patients with right ventricular pressure overload, the eccentricity index was significantly greater than 1.0 at both end-systole and end-diastole (1.44 +/- 0.16 and 1.26 +/- 0.11, respectively) (p less than 0.001). These results suggest that an index of eccentric left ventricular shape which reflects abnormal motion of the interventricular septum can be defined.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross-sectional echocardiographic analysis of the extent of left ventricular asynergy in acute myocardial infarction

Cross-sectional echocardiography was used to study left ventricular wall motion in 44 patients with myocardial infarction, and the extent of observed asynergy was correlated with left ventricular function. Echocardiographic studies were performed in short and long axes of the ventricle and nine segments were identified for analysis. Wall motion in each segment was classified as normal, hyperkinetic, hypokinetic, akinetic or dyskinetic. Based on this analysis a wall motion index was derived as an overall assessment of left ventricular asynergy. Left ventricular function was measured by clinical and hemodynamic parameters to note the presence of pulmonary congestion or peripheral hypoperfusion or both.Segmental asynergy was detected in all patients with acute myocardial infarction. Patients with uncomplicated infarction had a wall motion index of 3.2 ± 2.4, which was significantly less than that in patients with pulmonary congestion (9.7 ± 3.1, p < 0.001) or with both pulmonary congestion and hypoperfusion (10.6 ± 4.8, p < 0.001).In nine patients with acute ventricular septal defect or acute mitral regurgitation, wall motion index was 6.7 ± 1.9, significantly less than with other complicated infarcts (p < 0.001) but greater than with uncomplicated infarcts (p < 0.005). Wall motion index also discriminated complicated from uncomplicated infarction when death was used as the end point.Cross-sectional echocardiography provides a method of measuring the extent of left ventricular asynergy during acute myocardial infarction that correlates well with hemodynamic parameters of left ventricular function.

Exercise echocardiography: a clinically practical addition in the evaluation of coronary artery disease.

There has been only modest clinical interest in exercise echocardiography because of the technical limitations of the procedure. Recognizing that there have been recent technical advances in the echocardiographic instruments and that echocardiography should, in theory, be an ideal technique for evaluating exercise-induced wall motion abnormalities, a clinically practical method of performing exercise echocardiograms was developed. By obtaining the echocardiograms immediately after treadmill exercise, with the patient sitting at the treadmill, a high percent of studies adequate for interpretation was obtained (92%). The addition of echocardiography to the treadmill exercise test significantly enhanced the diagnostic yield. In addition, in cases of one and three vessel disease, exercise echocardiography identified stenosis in specific coronary arteries. In patients with two vessel disease and left circumflex obstruction, specific vessel identification was less reliable. A high percent of patients with multivessel disease developed wall motion abnormalities with exercise that persisted for at least 30 minutes. It is concluded that echocardiography performed immediately after exercise with the new generation of echocardiographs can be a practical and useful clinical tool.

Cross-sectional echocardiography in acute myocardial infarction: detection and localization of regional left ventricular asynergy.

Left ventricular asynergy associated with acute myocardial infarction was evaluated by crosssectional echocardiography. Patients with acute infarction were studied within 48 hours of admission, and a segmental analysis of left ventricular wall motion was performed using nine segments obtained by short- and long-axis recordings of the left ventricle. By this segmental approach, analysis of wall motion in the entire left ventricle was possible. Complete studies were recorded in 37 of 44 original patients. Segmental wall motion abnormalities were recorded and localized in each of the 37 study patients. Asynergy was detected in 142 segments, and 29 patients had multiple segment involvement. Asynergy was most common in the apical segments of the left ventricle, but the cross-sectional scans permitted detection of asynergy in all segments. Correlation between the ECG and the cross-sectional echocardiogram revealed that 19 of 20 patients with inferior infarction had asynergy in posterior segments, 14 of 14 patients with anterior infarction had asynergy in anterior segments, and three of three patients with anteroinferior infarction had asynergy both anterior and posterior segments. In addition, the location of segmental asynergy followed specific patterns for each ECG subgroup of infarction. In four patients with postmortem examination, 21 of 22 segments that had asynergy by cross-sectional echocardiography also had pathologic evidence of infarction. Therefore, the cross-sectional echocardiogram provides a reliable method for detecting the presence and location of regional asynergy associated with acute myocardial infarction.

Assessment of myocardial perfusion abnormalities with contrast-enhanced two-dimensional echocardiography

A new echocardiographic contrast agent, gelatin-encapsulated microbubbles, that an intramyocardial contrast effect, was evaluated as a marker for the detection of regions of abnormal myocardial perfusion in nine open-chest dogs. The gelatin-encapsulated microbubbles were injected into the aortic root under control conditions and during circumflex coronary artery occlusion. Myocardial perfusion was simultaneously assessed with radioactive microspheres. Echocardiographic contrast enhancement (ECE) was measured in footlamberts (Ft-L) from the videoscreen of an off-line playback system, using a commercially available light meter. A single short-axis section of the left ventricle was divided into octants to analyze myocardial perfusion. The equivalent regions of the echocardiographic image were analyzed for contrast enhancement and wall motion. An ECE > 0.3 Ft-L was seen in all 120 octants analyzed before circumflex coronary artery occlusion and in 48 of 51 (94%) octants with > 50% of normal zone flow during circumflex artery occlusion. An ECE ≤ 0.3 Ft-L identified 19 of 21 octants (with ≤ 50% normal zone flow and all 13 octants with ≤ 25% normal zone flow during coronary artery occlusion. In contrast, wall motion abnormalities (akinesis or dyskinesis) were seen in 13 of 51 octants (25%) with > 50% normal zone flow, and normal wall motion was seen in two of 21 octants (10%) with blood flow ≤ 50% of normal zone flow during circumflex coronary artery occlusion. We could not demonstrate a linear correlation between ECE and the absolute level of myocardial blood flow. We feel this was due to the limitations imposed by imaging an open-chest animal preparation, variation in the number of gelatin-encapsulated microbubbles used for each injection and variations in the echocardiographic gain settings among experiments. We conclude that contrast-enhanced two-dimensional echocardiography with gelatin-encapsulated microbubbles can accurately identify ischemic regions of the left ventricular myocardium. This technique is more accurate than wall motion analysis for detecting myocardial ischemia.

Echocardiographic Features of Atrial Septal Defect

Echocardiographic studies were performed on 39 adult patients with atrial septal defects. Findings were compared with those from normal subjects, patients with other congenital left-to-right shunts (ventricular septal defect and patent ductus arteriosus), patients with uncomplicated right ventricular pressure overload (pulmonic stenosis and pulmonary hypertension), and patients with pulmonary hypertension complicated by tricuspid regurgitation. Two echocardiographic features were assessed: 1) a right ventricular dimension, or RVD Index, representing the distance between the right ventricular epicardial echoes and echoes from the right side of the interventricular septum divided by the patients body surface area, and 2) motion of the interventricular septum.The increased RVD Index and abnormal septal motion observed in the patients with atrial septal defects provided an ultrasound complex that could clearly separate these patients from normal individuals, those with ventricular septal defect and patent ductus arteriosus, and those with uncomplicated right ventricular pressure overload. However, patients with tricuspid regurgitation could not be differentiated from the group with atrial septal defects, indicating that this echocardiographic complex reflected a volume overload of the right ventricle.

Diastolic collapse of the right ventricle with cardiac tamponade: an echocardiographic study.

The value of a newly described echocardiographic sign for the detection of cardiac tamponade was retrospectively evaluated in 91 patients. M-mode echocardiograms were reviewed in 86 patients, 36 of whom had concurrent two-dimensional echocardiographic examinations; in five patients, only two-dimensional echocardiography was performed. Cardiac tamponade was clinically present in 17 patients, 14 of whom had abnormal posterior motion of the right ventricular free wall in early diastole. Two of the 17 patients with tamponade had equivocally abnormal motion and one had normal wall motion. The patient with normal wall motion was later proved to have predominantly constrictive pericardial disease. In all cases, the abnormal wall motion reverted to normal after a definitive drainage procedure. Two-dimensional echocardiography confirmed that the abnormal right ventricular wall motion represented a true collapse of the right ventricular cavity in early diastole. Of the 69 patients without clinical cardiac tamponade, only seven had abnormal right ventricular wall motion. Detection of abnormal diastolic right ventricular free wall motion may be a sensitive indicator or a hemodynamically significant pericardial effusion. Conversely, the presence of normal motion of the right ventricular free wall appears to be a reliable indicator that the pericardial effusion is exerting little effect on overall cardiac function.

Exercise cross-sectional echocardiography in ischemic heart disease.

We performed cross-sectional echocardiograms at rest, during supine bicycle exercise, and after sublingual nitroglycerin administration in 28 patients suspected of having ischemic heart disease. Technically adequate exercise cross-sectional echocardiograms were obtained in 20 patients (71%). Ten patients had new areas of reversible segmental dysynergy, and all 10 had significant stenoses of coronary arteries supplying areas of the heart corresponding to the location of reversible dysynergy. Six of these 10 patients also underwent exercise thallium-201 perfusion scanning, and all six had reversible perfusion defects in the area that demonstrated reversible dysynergy on exercise cross-sectional echocardiography. At least two of the remaining 10 patients who did not have reversible segmental dysynergy on exercise cross-sectional echocardiography probably experienced myocardial ischemia that we did not detect. We conclude that exercise cross-sectional echocardiography is technically difficult but feasible. The mechanical consequences of exercise-induced regional myocardial ischemia can be detected noninvasively by real-time, two-dimensional, cross-sectional echocardiography.

Complementary Value of Two-Dimensional Exercise Echocardiography to Routine Treadmill Exercise Testing

Two-dimensional echocardiograms were done during rest and after exercise in 95 patients who subsequently had coronary arteriography. Prior myocardial infarction was present in 36 patients, 35 of whom had wall motion abnormalities. There was no evidence of prior infarction in 59 patients, 44 of whom had coronary disease. In these 44 patients, the exercise electrocardiogram showed ischemia in 19, was normal in 13, and was nondiagnostic in 12. Exercise echocardiograms were abnormal in 35 of these 44 patients. In 15 patients without coronary disease, the treadmill response was nondiagnostic in 6, ischemic in 1, and normal in 8. Exercise echocardiograms were normal in 13 of these 15 patients. We conclude that exercise echocardiography is a valuable addition to routine treadmill testing. It may be of special value in patients with an abnormal resting electrocardiogram or a nondiagnostic response to treadmill testing or when a false-negative treadmill test is suspected.

Mechanism of abnormal septal motion in patients with right ventricular volume overload: a cross-sectional echocardiographic study.

SUMMARY To evaluate the mechanism of paradoxical septal motion in patients with right ventricular volume overload (RVVO), short axis cross-sectional, echocardiographic studies of the left ventricle (LV) and interventricular septum (IVS) were performed in 19 patients with paradoxical septal motion due to RVVO and in 20 normal subjects. Short axis study in normal subjects revealed the left ventricle to be a relatively circular structure during both diastole and systole. In patients with RVVO a change in LV diastolic shape was observed. This change in shape varied from a slight flattening of the LV and IVS during diastole to total reversal of the normal direction of septal curvature such that the IVS became concave toward the RV and convex toward the LV. During systole the LV and IVS returned to their normal relatively circular configuration. This change in LV shape from diastole to systole resulted in net motion of the IVS toward the right ventricle (paradoxically). This study therefore suggests that paradoxical septal motion in patients with right ventricular volume overload is a result of a change in the diastolic shape of the left ventricle.