Potential utility of left heart contrast agents in diagnosis of myocardial rupture by 2-dimensional echocardiography

Surgical treatment of post-infarction left ventricular free wall rupture: three cases review

Left ventricular free wall rupture (LFWR) is rare, but is one of the most serious complications of myocardial infarction and is associated with high mortality. Several operative techniques have been attempted, but early diagnosis and prompt surgical management are crucial for a positive patient outcome. We report three cases of LFWR successfully treated with surgical methods.

Left ventricular free wall impeding rupture in post-myocardial infarction period diagnosed by myocardial contrast echocardiography: case report

BACKGROUND

Left ventricular free wall rupture occurs in up to 10% of the in-hospital deaths following myocardial infarction. It is mainly associated with posterolateral myocardial infarction and its antemortem diagnosis is rarely made. Contrast echocardiography has been increasingly used for the evaluation of myocardial perfusion in patients with acute myocardial infarction, with important prognostic implications. In this case, we reported its use for the detection of a mechanical complication following myocardial infarction.

CASE PRESENTATION

A 50-year-old man with acute myocardial infarction in the lateral wall underwent myocardial contrast echocardiography for the evaluation of myocardial perfusion in the third day post-infarction. A perfusion defect was detected in lateral and inferior walls as well as the presence of contrast extrusion from the left ventricular cavity into the myocardium, forming a serpiginous duct extending from the endocardium to the epicardial region of the lateral wall, without communication with the pericardial space. Magnetic resonance imaging confirmed the diagnosis of impending rupture of the left ventricular free wall. While waiting for cardiac surgery, patient presented with cardiogenic shock and died. Anatomopathological findings were consistent with acute myocardial infarction in the lateral wall and a left ventricular free wall rupture at the infarct site.

CONCLUSION

This case illustrates the early diagnosis of left ventricular free wall rupture by contrast echocardiography. Due to its ability to be performed at bedside this modality of imaging has the potential to identify this catastrophic condition in patients with acute myocardial infarction and help to treat these patients with emergent surgery.

[Contrast echocardiography for detection of incomplete rupture of the left ventricle after acute myocardial infarction]

Myocardial rupture is a major complication after acute myocardial infarction. With complete rupture of the free left ventricular wall cardiac tamponade occurs with fatal outcome in most cases. With partial rupture, however, hemorrhage is slower, allowing days or weeks for diagnosis. Survival of these patients strongly depends on early recognition of this complication followed by immediate surgical intervention. Echocardiography is the diagnostic tool of choice to detect myocardial rupture with consecutive hemopericardium but diagnosis remains difficult even if suspected. We describe the case of a patient with inferior infarction who presented with cardiogenic shock, echocardiographic signs of pericardial effusion and abnormal motion and myocardial irregularities of the inferior wall. With Doppler echocardiography no flow across the wall was detected. Left heart contrast echocardiography confirmed the diagnosis of suspected myocardial rupture by clear deliniation of the defect. Immediate surgical repair was successfully performed in this patient with favorable long-term outcome. Thus, echocardiography early after acute myocardial infarction is useful in detecting subsequent complications and the use of contrast echocardiography should be considered in suspected myocardial rupture.

Role of contrast echocardiography in the assessment of myocardial rupture

Left ventricular free wall rupture is known to complicate acute myocardial infarction and is the second most common cause of inhospital mortality in this patient population. Contrary to widely held medical belief, this does not always result in immediate fatal pericardial tamponade with hemodynamic collapse. Up to 40% of such occurrences are subacute and may evolve over hours or even days. A high index of suspicion and accurate diagnostic tests are required to identify and treat these patients with emergent surgery. Echocardiography has emerged as an important diagnostic modality to identify this catastrophic condition. Although the literature has scattered reports on the role of transesophageal and transthoracic echocardiography in diagnosing free wall rupture, to date, only one report in the literature used ultrasound contrast agents to better delineate echocardiographic findings. We will present two cases in which echocardiography with use of intravenous ultrasound contrast agents was instrumental in helping to exclude rupture in one case and help identify rupture in another.

Clinical Application and Technical Considerations for the Use of Contrast Agents in the Echocardiography Laboratory

Contrast imaging represents a new and exciting application to the field of ultrasonography. As with the introduction of new imaging modes (i.e., color flow imaging) or examination (i.e., stress echocardiog-raphy), a learning phase will be necessary. For optimal contrast use, it is important to understand what microbubbles are designed to enhance, how to optimize the imaging system, and how to interpret the resulting images. Types of administration and use of the agents are also important to understand. This article will offer technical tips and helpful hints to shorten the sonographer's learning curve to successfully implement optimal contrast imaging for cardiac applications.

Use of contrast echocardiography in the diagnosis of subacute myocardial rupture after myocardial infarction

Myocardial rupture is an uncommon and catastrophic complication after acute myocardial infarction. It can present in an acute form or in a subacute form, with slower hemorrhage and thrombus formation at the site of rupture. These patients can survive several hours or days before the diagnosis is confirmed and the myocardial ruptured repaired. Two-dimensional Doppler echocardiography is very useful in the diagnosis of this complication, but the number of false-positive diagnoses is high, even in the presence of a large amount of pericardial effusion. In these patients, administration of a contrast agent can be useful to demonstrate active bleeding into the pericardium. We report a case of subacute myocardial rupture for which contrast echocardiography was useful in demonstrating the presence of persistent hemorrhage into the pericardium. To reduce the number of false-positive diagnoses, contrast echocardiography should be considered in patients with possible subacute myocardial rupture.

Contrast echocardiography: current and future applications

Recent updates in the field of echocardiography have resulted in improvements in image quality, especially in those patients whose ultrasonographic (ultrasound) evaluation was previously suboptimal. Intravenous contrast agents are now available in the United States and Europe for the indication of left ventricular opacification and enhanced endocardial border delineation. The use of contrast enables acquisition of ultrasound images of improved quality. The technique is especially useful in obese patients and those with lung disease. Patients in these categories comprise approximately 10% to 20% of routine echocardiographic examinations. Stress echocardiography examinations can be even more challenging, as the image acquisition time factor is critically important for accurate detection of coronary disease. Improvements in image quality with intravenous contrast agents can facilitate image acquisition and enhance delineation of regional wall motion abnormalities at the peak level of exercise. Recent phase III clinical trial data on the use of Optison and several other agents (currently under evaluation) have revealed that for approximately half of patients, image quality substantively improves, which enables the examination to be salvaged and/or increases diagnostic accuracy. For the "difficult-to-image" patient, this added information results in (1) enhanced laboratory efficiency, (2) a reduction in downstream testing, and (3) possible improvements in patient outcome. In addition, substantial research efforts are underway to use ultrasound contrast agents for assessment of myocardial perfusion. The detection of myocardial perfusion during echocardiographic examinations will permit the simultaneous assessment of global and regional myocardial structure, function, and perfusion-all of the indicators necessary to enable the optimal noninvasive assessment of coronary artery disease. Despite the added benefit in improved efficacy of testing, few data exist regarding the long-term effectiveness of these agents. Currently under evaluation are the clinical and economic outcome implications of intravenous contrast agent use for daily clinical decision making in a variety of patient subsets. Until these data are known, this document offers a preliminary synthesis of available evidence on the value of intravenous contrast agents for use in rest and stress echocardiography. At present, it is the position of this guideline committee that intravenous contrast agents demonstrate substantial value in the difficult-to-image patient with comorbid conditions limiting an ultrasound evaluation of the heart. For such patients, the use of intravenous contrast agents should be encouraged as a means to provide added diagnostic information and to streamline early detection and treatment of underlying cardiac pathophysiology. As with all new technology, this document will require updates and revisions as additional data become available.