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Heart Attack

What Are The Complications Of A Heart Attack?

Last updated on:
29/03/2012

Contributing Author: Guy Slowik FRCS

Heart attacks vary widely in the amount of damage caused and whether there are any complications. Some people may suffer a mild heart attack with no associated complications, which is called an uncomplicated heart attack. Others may suffer a more extensive heart attack with a wide range of complications. Fortunately, treatments can prevent or reduce the impact of complications if they occur.

Complications depend on the:

  • Location of heart muscle damage (i.e. the right or left ventricles)
  • Extent of heart muscle damage
  • Time after the heart attack (i.e., immediate or weeks later)

Complications include:

Arrhythmias (Abnormal Heart Rhythms)

The heart is normally driven by electrical impulses that follow specific pathways through the heart muscle. A heart attack damages heart muscle and often disrupts these electrical pathways. Other stimulation of the body's nervous system and certain heart medications can also disturb the heart's electrical impulses. These changes cause abnormal heart rates and rhythms, called "arrhythmias."

Need To Know:

Some arrhythmias, such as atrial arrhythmias, such as atrial fibrillation or atrial flutter are mild. But others, such as ventricular arrhythmias or complete heart block, are life threatening, occur without warning, and usually happen within the first 24 hours after a heart attack.

Arrhythmias are a major cause of death following an acute heart attack. Early defibrillation (applications of electrical shocks to the heart) by rescue workers, combined with early detection and treatment of arrhythmias in coronary care units, have dramatically reduced both pre-hospital and in-hospital deaths caused by abnormal heart rhythms.

Both continuous ECG monitoring and standard 12-lead electrocardiograms help to screen for arrhythmias.

Arrhythmias may be treated with:

  • Medications
  • Electrical cardioversion, which is the application of electric shocks to the heart through the chest wall
  • Pacemakers, which regulate very slow heart rates due to blocks in the transmission of electrical impulses

Recurrent Ischemia Or Heart Attack

About 20 to 30 percent of heart attack patients experience pain that occurs after the heart attack. Called "postinfarction angina," this indicates that remaining blood flow to the heart muscle is inadequate. These patients are at increased risk for a subsequent heart attack, called reinfarction.

About 5 to 20 percent of these patients will experience another heart attack in the first six weeks following the original one. This second event may involve the same region of heart muscle or an entirely new region.

Aggressive management of angina following a heart attack helps to reduce the risk of a subsequent heart attack. Patients who experience such angina usually undergo immediate cardiac catheterization and cardiac angiography.

This is often followed by

  • Angioplasty or
  • Coronary artery bypass surgery

Both of these invasive procedures restore blood flow to the heart muscle and lower the risk of a subsequent heart attack.

Heart Failure

Damage to heart muscle from a heart attack may leave the heart unable to pump effectively. If 30 percent or more of the heart muscle in the wall of the left ventricle has been affected, it is likely the patient will develop congestive heart failure.

These patients may experience shortness of breath because of fluid in lung airways. This is caused by the fact that the heart cannot effectively pump blood forward through the body. This condition can usually be treated effectively with medications but may require cardiac bypass surgery.

Cardiogenic Shock

If 40 percent or more of the left ventricle's muscular wall has been affected, cardiogenic shock may occur. In cardiogenic shock, not enough functional heart muscle remains to pump blood to body tissues and organs to sustain important bodily functions. The heart is not able to provide sufficient blood flow to organs such as the brain, kidneys. As a result, the patient experiences very low blood pressure, rapid heart rate, mental confusion, decreased urine output, and cold arms and legs.

Patients with cardiogenic shock are treated with medications that either increase the amount of blood pumped or reduce the pressure the heart is pumping against. Some individuals may receive a device called an intraaortic balloon pump. The pump is inserted into the aorta, the major blood vessel that supplies blood to the body from the heart. Inflation of the pump increases the blood pressure in the aorta, which, in turn, increases blood flow to the coronary arteries and peripheral (far away) body tissues.

Individuals who experience a heart attack involving the wall of the right ventricle may show signs of right heart failure, such as distended neck veins and leg swelling. These individuals are usually treated with medications.

In many cases, the best treatment for cardiogenic shock is bypass surgery.

For detailed information about bypass surgery, go to Cardiac Bypass Surgery.

Thrombus (Blood Clot) Formation

Erratic blood flow and a lack of blood flow in parts of the heart damaged by the heart attack can cause clots to form in the heart's chambers. This is especially true if the heart attack has involved the tip of the left ventricle or when an aneurysm has formed.

Inactivity due to bed rest increases the risk of blood clots forming in the deep veins of the legs. These clots can break off and travel through veins to the lungs, where they may cause a blood clot in pulmonary arteries.

Need To Know:

Preventive measures can dramatically reduce the risk of blood clot formation in a heart chamber or blood vessel after a heart attack.

  • The use of anticoagulants or blood thinners in patients at high risk for developing blood clots that could travel through the body's arteries
  • Placing elastic stockings on the legs

Mechanical Complications

When a heart attack damages muscle, this can lead to the formation of tears or holes in the heart's wall, which in turn affects heart function. These developments are referred to as mechanical complications.

Types of mechanical complications include:

  • Papillary muscle rupture: the tearing of muscle that attaches to heart valves, which are tissue flaps that direct blood flow through the heart
  • Ventricle free wall rupture: the tearing of the heart muscle wall of the left ventricle, causing blood to fill the fibrous sac that surrounds the heart
  • Ventricular septal rupture: the tearing of the wall between the right and left ventricles, causing blood flow to pass between these heart chambers
  • Aneurysm formation: the dilation or enlargement of a heart chamber due to weakness of its muscular wall

These complications are rare, but can cause varying degrees of heart problems and even death. Complications such as ventricular wall rupture may occur within two weeks of the heart attack, while others such as aneurysm formation may happen weeks or months later. The outcome depends on the degree of damage and swiftness of detection and treatment.

Screening for mechanical complications includes:

  • Watching for signs of heart failure, such as shortness of breath or leg swelling
  • Listening with a stethoscope for new heart murmurs, which would suggest that heart valves are not working properly or that blood is flowing through the wall that divides the ventricles
  • Echocardiography to look at the structure and function of the heart chambers, including blood clots associated with aneurysm formation
  • Electrocardiography to look for electrocardiogram (ECG) changes that may occur with aneurysm formation.
  • Chest x-ray to look for "bulging" of the left ventricle, which would suggest an aneurysm

Doctors and other members of the medical team closely monitor patients for such complications. Monitoring continues after patients leave the hospital at follow-up appointments. Tests performed prior to hospital discharge can often determine the potential for such future problems.

Pericarditis

Acute pericarditis, the short-term inflammation of the fibrous sac that encloses the heart, may occur early after a heart attack. Symptoms include pain and fever. A pericardial friction rub may be heard with a stethoscope. This finding is helpful in distinguishing between pericarditis and angina that is occurring after a heart attack.

The increased use of clot buster drugs has decreased the frequency of pericarditis. These medications limit the extent of both heart muscle damage and inflammation. If pericarditis does occur, it can be treated with aspirin.

 
 

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From Andrew Maynard - Chair of the University of Michigan Department of Environmental Health Sciences, with help from David Faulkner - 2013 Master of Public Health graduate.