Echocardiography in the Recognition and Management of Mechanical Complications of Acute Myocardial Infarction

PURPOSE OF REVIEW

Although rare, the development of mechanical complications following an acute myocardial infarction is associated with a high morbidity and mortality. Here, we review the clinical features, diagnostic strategy, and treatment options for each of the mechanical complications, with a focus on the role of echocardiography.

RECENT FINDINGS

The growth of percutaneous structural interventions worldwide has given rise to new non-surgical options for management of mechanical complications. As such, select patients may benefit from a novel use of these established treatment methods. A thorough understanding of the two-dimensional, three-dimensional, color Doppler, and spectral Doppler findings for each mechanical complication is essential in recognizing major causes of hemodynamic decompensation after an acute myocardial infarction. Thereafter, echocardiography can aid in the selection and maintenance of mechanical circulatory support and potentially facilitate the use of a percutaneous intervention.

Endoscopy-guided transesophageal echocardiography for large esophageal varices: Use of the "Double Barrel" technique

Rhythm control strategies in patients with esophageal varices and atrial arrhythmias pose a unique challenge. The left atrium should be imaged for a thrombus prior to attempting cardioversion or ablation, but the presence of varices is a relative contraindication for transesophageal echocardiography. We present a safe, novel technique of evaluating for left atrial thrombus with simultaneous transesophageal echocardiography and esophagogastroduodenoscopy using slim probes in a patient with large, high-risk esophageal varices, and symptomatic atrial flutter with rapid ventricular rates despite medical therapy.

Substernal epicardial echocardiography: review of a new technique

BACKGROUND

Patients after cardiac operation pose a challenge to the treating physician-these patients may become critically ill and are among the most difficult to image using transthoracic echocardiography. Several factors contribute to this, including difficulties in positioning the patient, inability of the patient to cooperate with instructions, surgical dressings, and hyperinflated lungs. Transesophageal echocardiography may be performed when transthoracic echocardiography is not diagnostic; however, transesophageal echocardiography is semi-invasive and does not lend itself to prolonged or repeated monitoring.

METHODS

Recently, a new approach to echocardiography for use in the patient after operation has been introduced with the modification of the standard mediastinal drainage tube to allow for substernal epicardial echocardiography (SEE). The SEE tube has 2 lumens. The first allows for routine mediastinal drainage and the second has a blind end that permits the insertion of a standard transesophageal echocardiographic probe for high-resolution imaging as often as is desired over the period during which the mediastinal tube is in place.

CONCLUSION

This article reviews the technique of SEE including a description of the method of performance of SEE (with representative images), a review of the published literature on this new modality, examples of clinical use, and a discussion of the advantages, indications, and limitations of SEE with an eye toward future directions for research.

Effect of treatment on the incidence of stroke and other emboli in 519 patients with severe thoracic aortic plaque

Severe aortic plaques seen on transesophageal echocardiography (TEE) are a high-risk cause of stroke and peripheral embolization. Evidence to guide therapy is lacking. Retrospective information was obtained regarding the occurrence of embolic events (stroke, transient ischemic attacks, or peripheral emboli) in 519 patients with severe thoracic aortic plaque seen on TEE since 1988. Treatment with statins, warfarin, or antiplatelet medications was noted. Treatment was not randomized. In a matched-paired analysis, each patient taking each class of therapy was matched for age, gender, previous embolic event, hypertension, diabetes, congestive failure, and atrial fibrillation to someone not taking that medication. Multivariate analysis was also performed. An embolic event occurred in 111 patients (21%). Multivariate analysis showed that statin use was independently protective against recurrent events (p = 0.0001). Matched analysis also showed a protective effect of statins (p = 0.0004; absolute risk reduction 17%, relative risk reduction 59%, number needed to treat [n = 6]). No protective effect was found for warfarin or antiplatelet drugs. The odds ratio for embolic events was 0.3 (95% confidence interval [CI] 0.2 to 0.6) for statin therapy, 0.7 (95% CI 0.4 to 1.2) for warfarin, and 1.4 (95% CI 0.8 to 2.4) for antiplatelet agents. Thus, there is a protective effect of statin therapy, and no significant benefit of warfarin or antiplatelet drugs on the incidence of stroke and other embolic events in patients with severe thoracic aortic plaque on TEE.

Echo contrast-enhanced diagnosis of atrial septal defect

Pulsed wave, continuous wave, and color flow Doppler imaging as well as intravenously administered agitated saline solution can detect intracardiac shunts during transthoracic echocardiography. Ultrasonographic contrast agents have greatly improved the visualization of left heart chambers and can enhance signals from blood flow within chambers and across valves, increasing the sensitivity of Doppler techniques. We describe a patient in whom the use of echo contrast media during transthoracic echocardiography allowed the detection of a previously unseen atrial septal defect. Combining such modalities may help to increase the sensitivity of transthoracic echocardiography and may eliminate the need for transesophageal echocardiography in selected patients.