Role of echocardiography in patients with coronary artery disease

Echocardiographic assessment of myocardial ischemia

Over the last 60 years, echocardiography has emerged as a dominant and indispensable technique for the detection and assessment of coronary heart disease (CHD). In this review, we will describe and discuss this powerful tool of cardiology, especially in the hands of an experienced user, with a focus on myocardial ischemia. Technical development is still on-going, and various new ultrasound techniques have been established in the field of echocardiography in the last several years, including tissue Doppler imaging (TDI), contrast echocardiography, three-dimensional echocardiography (3DE), and speckle tracking echocardiography (i.e., strain/strain rate-echocardiography). High-end equipment with harmonic imaging, high frame rates and the opportunity to adjust mechanical indices has improved imaging quality. Like all new techniques, these techniques must first be subjected to comprehensive scientific assessment, and appropriate training that accounts for physical and physiological limits should be provided. These limits will constantly be redefined as echocardiographic techniques continue to change, which will present new challenges for the further development of ultrasound technology.

Echocardiographic findings in ventricular septal rupture and anterior wall aneurysm complicating myocardial infarction

Echocardiographic findings in a patient with ventricular septal rupture and anterolateral wall aneurysm complicating myocardial infarction are presented. The findings were confirmed by cardiac catheterization and surgery. Using M-mode ultrasonocardiography one was able to demonstrate and localize the aneurysm as well as the ventricular septal defect which presented as an oblique interventricular communication appearing only during systole. Thus echocardiography supplemented the invasive examinations in exactly revealing the site of ventricular septal rupture. Other echocardiographic features of ventricular septal rupture were right ventricular dilatation, pathological septal motion and abnormal tricuspid valve motion as recently reported by other authors.

Usefulness of multiaxis echocardiography in assessment of the left ventricle in ischemic heart disease. A review

Echoventriculography, a multiaxis M-mode echocardiographic technique, was developed to examine in detail the regional wall motions of the left ventricle. The basic technical aspects and limitations are described, and experience is reviewed on 263 healthy subjects or patients with ischaemic heart disease. The reliability in detecting site and size of asynergic segments was excellent as related to electrocardiographic and thallium scintigraphic sites of acute infarction, and with left ventricular cineangiograms in chronic coronary heart disease. The correlation with pathologic anatomic size of infarct in 24 consecutive patients was r = 0.88 (p less than 0.001) when expressed by a percentage of the left ventricular horizontal circumference. 94% of 111 infarcted segments were correctly detected by echo; only the posteroseptal and the most lateral regions remain out of the methodological range. The method separated old infarct scars from fresh necrosis. Decreasing echo contraction index correlated with increasing severity of coronary obstructions in 43 patients studied for coronary artery surgery. In 15 infarct patients the M-mode technique was more sensitive than two-dimensional echocardiography in recording asynergic segments or endocardial echoes. The multiple segmental echoventriculographic index decreased parallel with clinical severity of acute infarction (r = -0.79, p less than 0.001; 30 patients). There was a 88% (p less than 0.01) concordance between the reduction of the ST segments (-30%) and the recovery of the mechanical function in the ischaemic myocardial segments (+26%) after beta blockade with pindolol in 22 patients with acute infarction. Methylprednisolone showed no improvement. With dopamine the left ventricular size decreased markedly (p less than 0.0005). Echoventriculography thus seems to be very informative in evaluation of chronic or acute left ventricular dysfunction, despite the rather demanding nature of the technique in practice.

M-mode echocardiographic mapping in differentiation of normal from dysfunctioning left ventricular myocardium. A study of patients with severe myocardial infarction and healthy controls

Seventeen severely ill patients with acute myocardial infarction (AMI) (12 men and 5 women; mean age 65) and 37 healthy persons with similar age and sex distribution were investigated. Regional left ventricular wall motion was studied in terms of mean wall velocity, in 16 segments, 8 basal and 8 apical, by M-mode echocardiographic (Echo) mapping from 6 probe positions. Adequate Echo registrations were obtained from 88% of the total of 864 segments. The best classification (88.5%) of normal and infarcted segments was obtained with a -30% deviation of mean systolic wall velocity (Vmean) values from the mean values of the control segments (CS). Non-infarcted segments (NIS) in the AMI group had significantly lower Vmean values than the CS (p less than 0.001). Subendocardially (SIS) and transmurally (TIS) infarcted segments could be clearly separated from both CS and NIS (p less than 0.001). Per cent deviation of Vmean from the mean value of the control segments (PD-V) for SIS varied considerably overlapping CS, NIS and TIS. With a PD-V between 0 and -30% the probability of NIS is 94%, SIS 6% and TIS less than 1%. A PD-V more than -66% was rarely seen among NIS (2%) but was the normal finding in TIS (94%).

Quantification of left ventricular wall dysfunction by M-mode echocardiographic mapping in heart failure following acute myocardial infarction

Echocardiographic mapping was performed in 44 patients on arrival in hospital and day 2 following acute myocardial infarction (AMI). To evaluate left ventricular (LV) function the per cent deviation of the mean systolic wall velocity (PD-V) from the normal was measured from 16 LV segments. Adequate data were obtained from 89% of the segments. The number of hypokinetic segments was somewhat higher in anterior than inferior AMI, reaching significance (p less than 0.05) on day 2. Dyskinetic segments were also more common in patients with anterior infarction (p less than 0.001), who also had significantly higher enzyme maxima than patients with inferior AMI (p less than 0.01). Enzyme maxima correlated well with the sum of PD-V from all hypokinetic segments on day 1 (r = 0.79, p less than 0.01). Compensatory hyperkinesia was more common in inferior than anterior AMI (p less than 0.001). Global LV function, estimated by subtracting the number of hyper- from hypokinetic segments (score sigma S:Adj), was significantly related to heart failure (Killip classification) (p less than 0.01) and the respiratory rate (r = 0.71, p less than 0.01) in the acute phase as well as to heart failure during the first post AMI month (New York Heart Association classification).

Pseudodyskinesis of the inferior left ventricular wall: recognizing an echocardiographic mimic of myocardial infarction

INTRODUCTION

Dyskinesis is diagnosed by outward systolic bulging, but a similar inferior wall (IW) motion is sometimes observed in patients without infarction. Such diastolic flattening of the IW is followed by systolic rounding and outward bulging, consistent with extrinsic diastolic compression that is overcome by systolic contraction.

HYPOTHESIS

Pseudodyskinesis (PD) (paradoxical IW motion) is associated with preserved systolic wall thickening and does not reflect ischemic dysfunction.

METHODS

We compared 100 consecutive patients having a pattern of PD on transthoracic echocardiography with control groups of 50 patients with documented inferior myocardial infarction and 50 healthy individuals. Percent systolic thickening of the inferior, anterior, septal, and lateral left ventricular (LV) walls was measured in a midventricular short-axis view, and LV cross-sectional shape was evaluated by the ratio of two perpendicular diameters. Diaphragmatic position was evaluated on chest radiograph.

RESULTS

Systolic IW thickening was not significantly different in PD from that of normal (58.2 +/- 6.2% vs 53.0 +/- 4.6%) and of non-IW in the same patients (50.4 +/- 6.8%). The LV was circular (diameter ratio = 1.0) in systole and diastole in healthy individuals; in PD, it was noncircular in diastole consistent with IW compression (P < .01), and circular in systole; in inferior myocardial infarction, it was circular in diastole and noncircular in systole (P < .01) consistent with decreased IW contraction. The left hemidiaphragm was more elevated in PD (78% vs 8.5%, P < .01).

CONCLUSIONS

In PD, the IW thickens normally to produce a circular LV cavity in systole. This motion, consistent with extrinsic compression, is important to distinguish from inferior myocardial infarction.

The evolution of stress echocardiography

The feasibility of using echocardiography to identify stress induced wall motion abnormalities was first demonstrated with M-mode recordings. The practical use of such a test had to await the development of 2-dimensional echocardiography whereby more wall segments could be analyzed. From the early days of 2-dimensional echocardiography there have been a succession of technological and clinical advances which have made stress echocardiography a very clinically useful tool in the management of patients with known or suspected coronary artery disease. These developments included the realization that stress-induced wall motion abnormalities produce stunned myocardium permitting immediate posttreadmill echoes to be clinically useful, the use of pharmacologic stress, the introduction of digital recording techniques so that rest and stress images could be viewed side-by-side, and more recently the advent of new imaging technologies, such as harmonic imaging of tissue to provide higher quality of stress echocardiograms.

Diastolic mitral regurgitation in patients with first-degree atrioventricular block

Diastolic mitral regurgitation has been observed in patients with DDD pacemakers when the atrioventricular (AV) delay was prolonged. However, diastolic mitral regurgitation associated with first-degree AV block has not been fully studied. We examined transmitral blood flow in 24 patients with first-degree AV block and normal cardiac function (ages 35.3 +/- 17.4 years), and in nine patients with DDD pacemakers and normal cardiac function (ages 73.1 +/- 8.1 years), using pulsed Doppler echocardiography. Diastolic mitral regurgitation was observed in 19 of 24 patients with first-degree AV block. Although PQ interval was shortened from 0.32 +/- 0.06 to 0.20 +/- 0.05 seconds (P < 0.01) after 1 mg atropine sulfate IV, the interval between P wave (ECG) and the beginning of diastolic mitral regurgitation did not change, while the duration of diastolic mitral regurgitation was shortened from 0.15 +/- 0.03 to 0.05 +/- 0.03 seconds (P < 0.01). There was a significant correlation between changes in PQ interval and changes in the duration of diastolic mitral regurgitation (r = 0.92, P < 0.001). Although cardiac output (3.9 +/- 0.05 L/min) and pulmonary capillary wedge pressure (5.1 +/- 1.5 mmHg) were normal in all patients with pacemakers, diastolic mitral regurgitation was observed when the AV delay was prolonged. The critical PQ interval for the appearance of diastolic mitral regurgitation was 0.23 +/- 0.01 seconds. In patients with prolonged PQ intervals, delayed ventricular contraction following atrial contraction may be associated with mitral regurgitation in the presence of a reversed AV pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced left ventricular cavitary activity ("black hole sign") in thallium-201 SPECT perfusion images of anteroapical transmural myocardial infarction

Apparently reduced left ventricular (LV) cavitary thallium activity in both planar and tomographic perfusion images has been previously observed by these and other investigators. With single-photon emission computerized tomography, we have clinically noted that this "black hole sign" was associated with an aneurysm in the setting of a transmural anterior or anteroapical perfusion defect. We have now prospectively studied the etiology and predictive value of this sign in 84 consecutive patients with an anterior, anteroapical transmural perfusion defect. Of the 84 patients, 49 had both LV aneurysm (confirmed by contrast ventriculography, echocardiography or gated blood pool studies) and a black hole sign. Only 1 patient with an aneurysm did not have the black hole sign, and 2 without aneurysm did. Thus, it is concluded that this sign is highly accurate in diagnosing LV aneurysm. Because thallium-201 single-photon emission computerized tomography imaging is often performed as one of the first diagnostic tests soon after myocardial infarction, this has important clinical management implications.

Intraoperative monitoring of regional wall motion abnormalities for detecting myocardial ischemia by transesophageal echocardiography

Transesophageal two-dimensional echocardiography has been used for intraoperative monitoring of regional wall motion of the left ventricle. Regional wall motion abnormality is a sensitive indicator of myocardial ischemia and the use of two-dimensional transesophageal echocardiography may have a substantial advantage for early detection of myocardial infarction and thus for initiating timely and appropriate therapy in preventing postoperative myocardial ischemia. With an expected increase in the use of intraoperative transesophageal echocardiography for monitoring regional wall motion, we described the practical aspects of transesophageal echocardiography: (1) insertion technique of transesophageal echocardiographic probe; (2) the technique for obtaining an optimal short-axis view of the left ventricle; and (3) the method for evaluating regional wall-motion abnormality and myocardial ischemia. Regional wall motion abnormality is best monitored at the mid-papillary muscle level where all three coronary arteries meet. In obtaining this view, the transesophageal echocardiographic probe was found to be predominantly located in the stomach. Failure in obtaining short-axis view of the left ventricle at this level occurred in patients with left ventricular dilatation or obesity. Because of the anatomical reason, the echocardiographic transducer cannot reach a proper plane. In anesthetized patients, air can be pushed into the stomach during induction and may disturb the visualization. The pitfalls in examining regional wall motion abnormalities include: (1) shifting of the center of left ventricular contraction; (2) inadequate direction of the scanning plane; and (3) paradoxical septal movement. Three cases are presented to demonstrate the usefulness of transesophageal echocardiography in managing coronary artery surgical patients.

Clinical and echocardiographic features of isolated severe pure mitral regurgitation

Recent studies have shown that rheumatic heart disease is no longer the main cause of isolated severe pure mitral regurgitation. In this study, we evaluated various clinical and echocardiographic features found in the syndrome of mitral regurgitation. Our data is consistent with recent reports that mitral valve prolapse and coronary artery disease are now the predominant causes of mitral regurgitation and that rheumatic heart disease is a much less common etiology. In addition, our data suggest that clinical evaluation alone is usually very accurate in identifying the correct etiology. Various clinical and echocardiographic features found in the subsets of acute and chronic mitral regurgitation are described. Specifically, patients with acute mitral regurgitation were more likely to have echocardiographic evidence of segmental left ventricular dysfunction and flail mitral valve leaflet. In chronic mitral regurgitation, atrial fibrillation and left atrial dilatation were more commonly present. Echocardiography was found to be more useful in the detection of the complications of coronary artery disease rather than in identifying its presence. Patients with a New York Heart Association classification of IV and those with echocardiographic evidence of an increased left ventricular endsystolic dimension or left ventricular hypertrophy had a worse prognosis.

Three-dimensional echoventriculography

A method of generating a three-dimensional image of the human left ventricle by computer techniques is described. The volume of each image was estimated by a modification of Simpson's rule. The method was applied to nine suitable patients and estimations of end-diastolic and end-systolic volumes were compared to volumes determined by cineangiography. Significant linear correlation coefficients of 0.95 and 0.94 were obtained for end-diastolic and end-systolic volumes, respectively. The standard errors of estimate were 9 ml for end-diastolic volumes and 7 ml for end-systolic volumes. The value of this methodology lies in the ability to estimate left ventricular volumes with accuracy, using an imaging technique of little inconvenience and no risk to the patient and computer hardware that is readily available at most clinical institutions.

Imaging of the left ventricle in patients with ischemic heart disease: role of the contrast angiogram

The contrast left ventriculogram is the gold standard against which all other cardiac imaging techniques are measured. In the past decade, noninvasive methods such as radionuclide angiography, echocardiography, computed tomography (CT), and digital substraction imaging have become available. This review examines the role of these techniques, and whether they will supersede the selective contrast ventriculogram. Each of these modalities seems to have specific capabilities and superiority in a certain area. Contrast ventriculography is best suited for the functional assessment of the left ventricular wall. Isotopes and CT have great potential for evaluating the myocardium properly. Echocardiography produces good visualization of atrioventricular valves and intracavitary structures. The role of contrast angiography is considered in the workup of the cardiac patient. The contrast angiogram is closely related to the coronary angiogram in the assessment of the patient with arteriosclerotic heart disease and it is still a necessity for the preoperative evaluation of the patient with congenital heart disease.

Identification of transient and persistent segmental wall motion abnormalities in patients with unstable angina by two-dimensional echocardiography

To determine the value of real-time, two-dimensional echocardiography (2-D echo) in unstable angina, regional wall motion on serial short-axis 2-D echo recordings was analyzed and summed segment scores of abnormal motion were compared and classified according to each patient's clinical status 12 weeks after hospital discharge. Nineteen male patients who fulfilled criteria for unstable angina and responded to medical therapy underwent 2-D echo study within 48 hours of admission and discharge. Of 11 patients with abnormal 2-D echo scores on admission, five patients had reduced scores and six patients had similar or increased scores at discharge. Six of eight patients who had scores of zero on admission had scores of zero at discharge. At follow-up, 11 patients had minimal or no angina pectoris (group 1), and eight patients had worsening angina or recurrent unstable angina (group 2). At discharge, 2-D echo studies showed that all group 1 patients had reduced or zero scores, while group 2 patients retained or increased their abnormal scores. This study shows that in patients with unstable angina, both transient and persistent abnormalities can be identified by 2-D echo. Abnormal segmental wall motion was transient or absent in patients with a good outcome, and worsened or remained abnormal in patients with a poor outcome.

High predictive accuracy for detection of left main coronary artery disease by antilog signal processing of two-dimensional echocardiographic images

Two-dimensional echocardiography has been used to image the left main coronary artery. We have successfully imaged the left main coronary artery in 16 of 19 patients with left main coronary artery disease (LMCAD) and in 14 of 18 control patients using a dynamically focused 3-1/2 MHz experimental phased array sector scanner. Images were displayed with standard logarithmic compression grey scale allocation and with a modified antilog curve which enhances high intensity echoes. All of the 16 patients with LMCAD were identified from the antilog processed image. Only 1 of the 18 control patients had a false positive study. Modified antilog processed images provide high sensitivity (100%) and specificity (93%) for detecting LMCAD. This noninvasive technique could be used to screen patients for the presence or absence of LMCAD.

Echocardiographic detection of coronary artery disease. Detection of effects of ischemia on regional myocardial wall motion and visualization of left main coronary artery disease

M mode and cross-sectional echocardiographic studies at rest have been used to detect regional left ventricular wall motion abnormalities as a sign of hemodynamically significant coronary artery disease. These techniques have proved to be fairly specific but not highly sensitive. Detection of new regional wall motion abnormalities with cross-sectional echocardiography during exercise appeared practical in 80 percent of patients in preliminary studies; the finding of such abnormalities is highly specific for the presence of coronary artery disease and, with this approach, the sensitivity of echocardiography is improved. Thus, patients with anatomically severe coronary artery disease on angiography may not manifest an echocardiographic abnormality in regional wall motion even during exercise. The direct noninvasive detection of the left main coronary artery in up to 90 percent of patients studied with cross-sectional echocardiography using the short axis or apical approach, or both, has been well defined. A high sensitivity and specificity of detecting anatomically severe left main coronary artery disease using the criteria of both luminal impingement and the presence of high intensity echoes have been confirmed. Further advances in imaging techniques may allow for better definition of the coronary arterial tree.

M-mode echocardiography in anteroseptal myocardial infarction. Lack of sensitivity

Eighteen patients with documented anteroseptal myocardial infarction (ASMI) were investigated with both cardiac catheterization and M-mode echocardiography. All had greater than 75% occlusion of the left anterior descending artery (LAD), proximal to the first septal perforator in 12, and distal to it in 6; 17 of 18 had abnormal septal motion by angiography. In contrast, echocardiography revealed abnormal septal motion in only 5 of 18; two others had diminished septal wall thickness in relation to posterior ventricular wall. The presence of these echocardiographic signs was not dependent either on relation of stenosis to septal perforators or on presence of septal collaterals. Although abnormal septal motion by M-mode echocardiography may indicate ASMI, normal motion does not exclude it nor does it help localize stenosis of the LAD.

Echoventriculography in acute myocardial infarction. IV. Infarct size and reliability by pathologic anatomic correlations

A morphologic-echocardiographic comparison was carried out in 24 consecutive patients to determine the accuracy of multidirectional single-beam echocardiography in imaging the size and site of 22 fatal acute myocardial infarctions and of 2 postinfarction ventricular aneurysms treated surgically. Echocardiography never missed the infarction, regardless of whether the infarction was anterior or posterior. The correlation between the echocardiographic and pathologic anatomic extent of infarct, as expressed by a percentage of the left ventricular horizontal circumference, was r=0.88 (p less than 0.001). One hundred four of one hundred eleven infarcted segments (94%) were detected by echo; only the posterior septal and the most lateral segments of the left ventricle tended to remain out of range of the method. The regional asynergy at the center of the infarcted region was clearcut-systolic thickening was never seen and the systolic wall motion was paradoxical in 75% of the patients (mean, -20+/-2.0 mm). Analysis of the regional function from multiple sites characterized reduction of the left ventricular performance (p less than 0.0005) better than did the ejection fraction in the presence of asynergy. An old postinfarction scar was differentiated from the acute necrosis. Thus, segmental left ventricular akinesis or paradoxical motion as seen by multidirectional echocardiography permits noninvasively a reliable estimation of the extent of acute myocardial infarction.

The superiority of mitral E point-ventricular septum separation to other echocardiographic indicators of left ventricular performance

M-mode echocardiography, angiocardiography, and coronary arteriography were done in 40 patients with coronary heart disease, 12 with congestive cardiomyopathy, and 14 with no detectable cardiac or coronary abnormality. We measured mitral E point-ventricular septum separation (EPSS) at the moment of the E peak; the previously described method measures EPSS as the vertical distance between the nadir of systolic septal motion and the subsequent mitral E peak. Angiocardiographic ejection fractions correlated better with EPSS (r = 0.83) than with left ventricular (LV) end-diastolic internal diameter (r = 0.62), LV internal diameter systolic shortening fraction (r = 0.64), LV echocardiographic ejection fraction (r = 0.70), and LV posterior wall systolic thickening (r = 0.58). Patients with angiocardiographic ejection fractions below 55% usually had EPSS values over 10 mm by our method. Six false negatives and one false positive occurred. Our observations in patients with impaired LV performance suggest that LV dilatation, and especially dilatation of the LV outflow tract, is relatively more important than reduction in the amplitude of diastolic anterior mitral excursion in the production of high EPSS values. Although the usual method for measuring EPSS and ours are equally satisfactory, ours has certain theoretical advantages.

The noninvasive assessment of anomalous origin of the left coronary artery from the pulmonary artery

We present a patient with anomalous origin of the left main coronary artery from the pulmonary artery. We correlate the findings of echocardiography and myocardial imaging with angiography, and discuss the value of the noninvasive techniques in the diagnosis and in the followup of such patients.

A new, noninvasive technique for inducing post-extrasystolic potentiation during echocardiography

Left ventricular function was evaluated in 34 patients with the echocardiogram, and an external mechanical cardiac stimulator was used to induce a ventricular premature contraction (VPC) noninvasively. Extent of post-extrasystolic potentiation (PESP) was determined by comparing systolic dimensional shortening and ejection fraction of the sinus beat preceding the VPC to that of the potentiated beat which followed it. Using this technique, a VPC could be introduced into the cardiac cycle of 30 of the 34 patients, six of whom were free of obvious cardiac disease and 24 of whom had valvular, coronary or myopathic heart disease. The only complication observed was mild breast ecchymosis in a female patient. Systolic dimensional shortening and ejection fraction increased from control values by an average of 21% and 17% respectively, with a range of 0-100%. The degree of PESP was very reproducible in repeat studies and when the same patients were subsequently evaluated during a spontaneously occurring or catheter-induced VPC. The technique can safely and reliably induce post-extrasystolic potentiation during echocardiography and is a potentially important adjunct to the noninvasive evaluation of left ventricular function.

Echocardiography in ischemic heart disease

Echocardiographic findings in patients with ischemic heart disease are described; their correlations with clinical, hemodynamic and angiographic data are presented and discussed. Regional abnormalities of left ventricular wall motion and/or thickening during systole are detected in 84 per cent of patients with acute myocardial infarction and in a high percentage of patients with larger than or equal to 75 per cent narrowing of a major coronary artery. These abnormalities may occur with stress and may be reversible. Left ventricular wall thinning during systole indicates acute ischemia or infarction and thin, dense myocardial echoes indicate scar. Echocardiographic evidence of left ventricular dysfunction is useful in predicting heart failure and mortality in patients with acute myocardial infarction and in predicting surgical mortality for patients undergoing aneurysmectomy and/or coronary artery bypass surgery. Echocardiography has not proved useful in determining graft patency following coronary artery bypass surgery. Technical difficulties and limitations of echocardiography in patients with coronary artery disease are discussed.