MI Complications

Posted by Graham McMahon • December 31st, 2010

In this week’s Case Record of the Massachusetts General Hospital, A 68-Year-Old Woman with Chest Pain during an Airplane Flight Case, a woman with a history of hypertension and hyperlipidemia was admitted to the hospital because of substernal chest pain.

Rupture of the free wall of the left ventricle occurs in 1 to 4% of cases of acute myocardial infarction. It commonly presents as acute or recurrent chest pain followed by electromechanical dissociation.

Clinical Pearls

What are the risk factors for developing a mechanical complication after myocardial infarction?

Risk factors for mechanical complications after myocardial infarction include a first myocardial infarction without a history of angina, female sex, advanced age, hypertension, delayed recognition of myocardial infarction, and prolonged physical activity during myocardial infarction.

What mechanical complications after myocardial infarction are most common?

Rupture of a papillary muscle, leading to acute severe mitral regurgitation, was the most common mechanical complication in studies of cardiogenic shock. Other mechanical complications include myocardial perforation, pseudoaneurysm, rupture of the ventricular septum, and rupture of the free wall of the ventricle.

Table 2. Cardiac Causes of Shock after Myocardial Infarction.

Morning Report Questions

Q: How does rupture of the left ventricular free wall present?

A: Examination may reveal jugular venous distention, hypotension, pulsus paradoxus, and reduced intensity of heart sounds. When blood first enters the pericardial space, there may be a brief period of increased vagal tone, with  bradycardia, diaphoresis, and nausea.

Q: How should rupture of the free wall of the left ventricle be managed?

A: The best treatment is immediate surgery, although the prognosis remains poor, since it is challenging to get such critically ill patients to the operating room in time. Pericardiocentesis rarely leads to stabilization of a patient and, if performed, will show that the fluid is blood. If the pericardiocentesis relieves the tamponade, the relief will usually be transient, since the hypotension and tamponade will usually resume as blood continues to enter the pericardial space from the left ventricle.

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