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HEART ATTACK: PART ONE

© Kathleen Newton

The human heart is a complex organ. About the same size as an adult's fist, the heart is responsible for pumping blood through the body's estimated 60,000 miles of blood vessels. The human heart never goes on a break, and it never takes a day off. But like all other organs and systems within the body, the heart requires oxygen to survive. What happens when the flow of oxygen-rich blood to the heart is interrupted?

Heart attack, or myocardial infarction (MI), occurs when blood flow to an area of the heart is interrupted. This interruption in blood flow can be caused by:

A THROMBUS: A stationary blood clot that forms in a coronary artery.

An EMBOLUS: A blood clot formed elsewhere in the body. The embolus travels through the blood vessels and becomes lodged in a coronary artery.

ATHERSCLEROSIS: A coronary artery is obstructed by fatty plaque deposits on the inner walls of the artery. These deposits are composed mainly of cholesterol. Over time, these fatty deposits can completely block blood flow.

When an MI occurs, death of heart cells occurs in the area of the heart that is deprived of blood flow. The amount of damage depends on the location and size of the area affected. At best, only a small portion of the heart is affected, and the heart's strength is reduced minimally. If a large area of heart tissue is involved, disruptions in the heart's conducting system (which regulates heart function) can cause arrhythmias (irregular heart rhythms), and even sudden death.

NEXT WEEK: Risk factors for heart attack, and other disorders associated with impeded blood flow.

The copyright of the article HEART ATTACK: PART ONE in First Aid is owned by Kathleen Newton. Permission to republish HEART ATTACK: PART ONE in print or online must be granted by the author in writing.