Comparison of contrast angiography and two-dimensional echocardiography for the evaluation of left ventricular regional wall motion abnormalities after acute myocardial infarction

Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association

The management of low-risk patients presenting to emergency departments is a common and challenging clinical problem entailing 8 million emergency department visits annually. Although a majority of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent treatment of a serious problem and those with more benign entities who do not require admission. Inadvertent discharge of patients with acute coronary syndrome from the emergency department is associated with increased mortality and liability, whereas inappropriate admission of patients without serious disease is neither indicated nor cost-effective. Clinical judgment and basic clinical tools (history, physical examination, and electrocardiogram) remain primary in meeting this challenge and affording early identification of low-risk patients with chest pain. Additionally, established and newer diagnostic methods have extended clinicians' diagnostic capacity in this setting. Low-risk patients presenting with chest pain are increasingly managed in chest pain units in which accelerated diagnostic protocols are performed, comprising serial electrocardiograms and cardiac injury markers to exclude acute coronary syndrome. Patients with negative findings usually complete the accelerated diagnostic protocol with a confirmatory test to exclude ischemia. This is typically an exercise treadmill test or a cardiac imaging study if the exercise treadmill test is not applicable. Rest myocardial perfusion imaging has assumed an important role in this setting. Computed tomography coronary angiography has also shown promise in this setting. A negative accelerated diagnostic protocol evaluation allows discharge, whereas patients with positive findings are admitted. This approach has been found to be safe, accurate, and cost-effective in low-risk patients presenting with chest pain.

Echocardiography in the evaluation of patients in chest pain units

Using percutaneous angioplasty to induce the ischemic cascade in the cardiac catheterization laboratory, echocardiographic wall motion abnormalities have been documented to precede electrocardiographic abnormalities and angina. Therefore, detection of cardiac wall motion abnormalities is potentially more sensitive than the history, physical examination, and ECG for identification of myocardial ischemia. Echocardiography is highly reliable for assessing cardiac wall motion and, thus, it has been used for diagnosis and risk assessment in patients presenting to the emergency department (ED) with symptoms suggestive of myocardial ischemia. In patients who have acute ST-elevation myocardial infarction (MI), echocardiography is comparable to invasive left ventriculography for detecting wall motion abnormalities. However, the usefulness of echocardiography in the low-risk population that has chest pain of uncertain origin and a nondiagnostic initial presentation is less well established.

Acute ischemic syndromes. Chest pain center concept

CPCs have been developed to meet the clinical challenge posed by the diverse group of patients presenting to the ED with findings suggestive of a coronary event. Using a protocol-driven approach, high- and low-risk patients can be identified on presentation, facilitating urgent therapy in the former and triage of the latter to more deliberate management. Most CPCs focus on low-risk patients who are being increasingly managed by accelerated diagnostic protocols. These methods comprise systematic strategies that include innovative diagnostic approaches during a 6 to 12 hour period of observation with serial ECGs, continuous monitoring and cardiac biomarker measurements. A negative evaluation is usually followed by predischarge stress testing, and positive findings mandate admission. An essential aspect of the CPC strategy is continuity of care for patients with negative cardiac evaluations. Current data indicate that management of low-risk patients with chest pain in a CPC is safe accurate, and appears to be cost-effective.

Conditioned blood reperfusion during angioplasty (CoBRA) treatment of acute myocardial infarction

Acute myocardial infarct (MI) results in ischemia distal to lesions which puts heart muscle at risk for reperfusion injury (RI). Neutrophils, platelets and complement are putative mediators of RI. Recent advances in filtration technology provide integrated neutrophil and platelet removal together with complement-attenuating properties in a single blood-conditioning device. The present study characterizes the properties of a blood-conditioning filter and describes its clinical effect when used in conjunction with active hemoperfusion for acute MI. The filter reduces leukocytes by 99.9998 +/- 0.0002% (p<0.0001) and platelets by 99.9934 +/- 0.0069% (p<0.0001). Human plasma, derived from heparinized blood that was 'conditioned' by filtration, was studied using the Langendorff isolated rabbit heart preparation. The deposition of membrane attack complex and the resultant functional myocardial impairments [reflected in hemodynamic and biochemical measurements, including developed pressure, coronary blood flow, lymph-derived myocardial creatine kinase (CK)] are significantly attenuated by blood conditioning. Integration of the blood-conditioning filter into an active hemoperfusion system during primary percutaneous transluminal coronary angioplasty (PTCA) for acute MI (n=8) did not delay the procedure or cause any complications. Reperfusion of occluded coronary arteries with 300 cm3 of conditioned blood led to significant improvement in echocardiographic global wall motion scores (in standard deviations) following treatment (-1.64 +/- 0.18 to -1.45 +/- 0.15, p=0.02). Initial reperfusion of totally occluded coronary arteries with conditioned blood leads to acutely improved ventricular function. Collectively, these data provide a strong indication for continued investigation of conditioned blood reperfusion in angioplasty following acute MI for the long-term effect upon recovery of salvagable myocardium.

Intraoperative detection of segmental wall motion abnormalities with transesophageal echocardiography

PURPOSE

To compare two methods of analysis of regional wall-motion (RWM) using transesophageal echocardiography (TEE).

METHODS

Thirty patients undergoing coronary artery bypass surgery were studied. The transgastric short axis view at the mid-papillary level was recorded before and after cardiopulmonary bypass. All images were reviewed by an anesthesiologist trained in TEE and an echocardiographer. Regional wall motion was graded: 1 normal, 2 hypokinetic, 3 akinetic, and 4 dyskinetic. The left ventricle was evaluated according to the guidelines of the American Society of Echocardiography using 6-segment, and 4-segment models. Agreement between observers (interobservers), and for one observer at two different moments (intraobservers), for grading each segment was defined as RWM abnormality scores within 1 grade. A wall-motion score index (WMSI), which is the sum of individual scores divided by the number of segments visualized, was calculated. A Bland Altman analysis was used to assess interobserver variability.

RESULTS

Agreement between observers occurred in 96% and 94% of the examined segments, using 4- and 6-segment models respectively. Intraobserver agreement was 99% and 97% for the 4- and 6-segment models. The mean differences (bias) of the interobserver variability in grading the segments were 0.04 +/- 0.79 and 0 +/- 0.72 using a 4- or 6-segment model. The mean difference of the interobserver variability in WMSI were -0.05 +/- 0.42 and 0.05 +/- 0.37 using a 4- or a 6-segment model.

CONCLUSION

Both methods, using either a 4- or a 6-segment model, result in a high intraobserver and interobserver agreement, and a low interobserver variability.

Chest pain emergency units

Each year in the United States, more than 2 million patients are hospitalized with chest pain suggestive of myocardial ischemia, with fewer than 20% of these patients having an acute coronary event. Chest pain emergency units have been created to facilitate urgent therapy for patients with a serious cardiovascular event and to triage lower risk patients to less intensive, more cost-effective inpatient care or discharge to home. The clinical history, physical examination, and initial electrocardiogram are key to initial stratification of patients for further management, but additional methods are necessary to clearly distinguish patients with inconclusive findings at presentation as high- and low-risk. Innovative electrocardiographic methods have increased sensitivity for detecting myocardial ischemia. Accelerated diagnostic protocols with new cardiac serum markers can detect myocardial ischemia or infarction with increasing accuracy. Early echocardiographic, scintigraphic, and treadmill stress protocols can further evaluate patients who have nondiagnostic electrocardiograms and negative serum markers. This review presents the current status of chest pain emergency units and the evolving management strategies they encompass.

Prediction of single and multivessel coronary disease in patients after myocardial infarction according to quantitative ultrasound wall-motion analysis

Regional changes in left ventricular size and function characterize left ventricular remodeling and start very early after myocardial infarction. We studied the diagnostic value of left ventricular dyssynergic patterns in predicting the presence of single versus multivessel disease (MVD). Fifty-three consecutive patients with acute myocardial infarction were studied by ECG, two-dimensional echocardiography, and angiography during the same hospitalization. Thirty-eight normal subjects served as the control group. According to the angiographic findings, the patients were categorized as having: single-vessel disease (SVD, n = 17), two-vessel disease (n = 17), and three-vessel disease (n = 19). Two-dimensional echocardiography was performed and optimal frames from five cardiac cycles were digitized and quantitatively analyzed off-line with a microcomputer. Echocardiographic wall-motion analysis demonstrated a depressed regional segmental thickening in the infarcted area that was characteristic for each echocardiographic view. In the segments remote from the infarcted area, however, the three patient groups displayed differences in function that ranged from hyperkinetic in patients with SVD to hypokinetic in patients with MVD. Patients with SVD constantly displayed a wider range of segmental thickening when compared with patients with MVD and the control group (p < 0.05). In conclusion, patients with SVD after myocardial infarction display compensatory hyperkinesis of remote segments, which is attenuated in patients with MVD. The present study introduces new parameters of segmental myocardial function that might be helpful in predicting SVD and MVD in patients after myocardial infarction.

Digital echocardiography in myocardial infarction

Probably the most under-utilised application of echocardiography is in patients with coronary artery disease (CAD). This under-utilisation is striking since echocardiography can be very valuable in evaluating the natural history and therapy of CAD. One reason why echocardiography is not being utilised to its fullest is because of the reliance on videotape to record and display echocardiograms. This medium is time consuming and inconvenient for clinicians to review studies, it is not ideal for detecting subtle wall motion abnormalities, and videotape is impractical for comparing serial studies. Recording and storing echocardiograms on a digital medium overcomes these difficulties. Digital cine loops of single cardiac cycles provide great versatility. Multiple views or studies can be displayed simultaneously, subtle changes in wall motion are more easily detected and different views, or serial studies, can be readily compared. Such images can be displayed on computers on the ward or in the coronary care unit (CCU) and be available 24 hours a day, seven days a week at the convenience of the clinician. One does not need to find a recording on a two hour videotape, which may be in the ultrasound instrument, and one can view the exam in 30 sec instead of 5 to 10 min. Regional and global left ventricular function is one of the most important manifestations of CAD. With new therapeutic efforts at restoring myocardial function and limiting infarct expansion, assessing LV function is more important than ever. Digital echocardiography is an extremely practical and convenient way for clinicians to obtain this information.

Reference systems in echocardiographic quantitative wall motion analysis with registration of respiration

Registration of respiration allows analysis at the end-expiratory phase and may thus favor the use of the fixed-reference system versus the floating-reference system in echocardiographic quantitative wall motion analysis. Analysis is performed on two-dimensional echocardiograms of 44 normal subjects, 38 patients with anterior myocardial infarction, and 17 patients with posterior myocardial infarction. Two different models for wall motion analysis are applied, each using the fixed-reference system and the floating-reference system, respectively. In patients with anterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the anterior, septal, and apical walls, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. In patients with posterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the posterior wall, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. These findings indicate that the fixed-reference system is superior to the floating-reference system in quantification of wall motion of end-expiratory two-dimensional echocardiograms.