Detection of Complications of MI

Many life threatening complications can follow myocardial infarction.Development of these complications may necessitate urgent intervention or change in therapy for the survival of the patients. A carefully done echocardiographic examination can help in early detection of these complication.

Infarct Extension: Serial echocardiogram showing increase in the number of segments showing wall motion defect or decrease in segments functioning normally would indicate infarct extension, and merits urgent intervention. 

Two-dimensional echocardiography of patient with anteroseptal
myocardial infarction showing akinetic thinned out interventricular
septum and apex

Infarct Expansion: lnfarct expansion usually occurs in segments which are akinetic or dyskinetid. The number of infiacted segments remain the same,however, there is inct-ease in segmental or global circumference of the left ventricle on serial echocardiography. The segments become thinned out and expand. This is the biasis of ventricular reimodeling which impairs prognosis and function by increasing myocardial wall stress and tension and consequently oxygen demand. The remodeling can be prevented by ACE inhibitors and other afterload reducing agents.

Ventricular Aneurysm: Anterior infarcts are more commonly found to form ventricular aneurysms. These can be detected as outpouching of a particular segment producing deformed LV contour during diastole, which gets worsened during systole. The aneurysm besides being arrhythmogenic, is potential source of thrombus formation due to blood stasis. It can also lead to reduction in forward cardiac o u w t as the aneurysm accommodates a portion of it. Aneurysm is the end result of ibfarct expansion.
 

Ventricular Pseudoalneurysm: This is coinmoner in posterior infarcts. The characteristic finding is a breach in the continuity of the myocardium with an outpouching lined bp the pericardium. Colour Doppler can show flow in and out of the pseudoaneurysm. The genesis is as a result of myocardial perforation which is walled off by pericardium. The perforation may lead to cardiac rupture, tamponade and death. Thus urgent surgical correction is required.

Four chamber view.

Two-dimensional echocardiography of a patient with anteroseptal myocardial infarction

Ventricular Septa1 Pefect: This is another dreaded complication of myocardial infarction, which can be fatal unless surgically managed. The usual site of VSD is the junction of abnetic of dyskinetic area (infiacted territory) with a hyperkinetic area (donna1 territory). This is the place we should look for a VSD on echocardiograpby. Further more turbulent systolic color flow from left
ventricle into the right ventricle through the defect clinches the diagnosis. The important thing to note is that unconventional views may be required to highlight the defect.

Fig : Plax view-showing left to right flow across septum (VSD) in a patient with anterior wall myocardial infarction

Fig: Zoom view of septum in apical view showing flow across VSD

Mitral Regurgitation: Significant mitral regurgitation may result from papillary muscle rupture due to infarction. The echocardiogram shows flail mitral leaflets with evidence of papillary muscle rupture, there is systolic noncoaptation, and mitral tips pointing towards the left atrium with significant MR on colour Doppler.

Two-dimensional echocardiography with colour Doppler in a patient with
inferior wall myocardial infarction. Apical four-chamber view shows
mitral regurgitation

The MR jet continuous wave trace shows early deceleration indicating high LA pressures. In cases with difficult window transesophageal echo may be helpful in the diagnosis.

Other causes of mitral regurgitation may be ischemia which leads to systolic non coaptation with leaflet pointing toward LV side. This may appear on stress and get relieved with rest on stress echocardiogram. The papillary muscles may be thick scarred and calcific as a result of healed infarction. This may lead to significant MR.

Mural Thrombi: The thrombi are seen as echogenous mass fixed or mobile usually at or adjacent to a dyskinetic or akinetic area, which is commonly aneurysmally dilated. Echocardiography is supposed to be a gold standard for dktection of thrombi.

PIax view-large mural thrombus attached tb
anterior septum - Apical four chamber view showing large
thrombus attached to akinetic apex

(Two-dimensional edhocardiography in a patient with large anteroseptal myocardial infarctiop)

Thrombi usually ocdur at the apex following anterior wall infarction. The trick to find thrombi is to tdoroughly evaluate the dyskinetic, akinetic and aneurysmal areas by convention81 and unconventional views using a high resolution, high
frequency i.e. 5 Mega Hz transducer.

Right Ventricular Infarct: This is commonly associated with inferior wall infarction and is cotbmonly missed until a high index of suspicion is maintained on clinical and elecl/rocardiographic grounds. The echo shows dilated and hypokinetic RV in dddition to inferior wall motion defects. The criteria may be important specially iwhen the EKG changes, which are usually transient, settle down.