Health Information

Acute Myocardial Infarction

2022.11.21

Causes

Acute Myocardial Infarction (AMI) is usually caused by atherosclerosis and thrombosis of coronary arteries. Heart is an important organ which pumps blood to various tissues in our body. Coronary arteries are blood vessels which supply blood, oxygen and nutrients for heart muscles to work. With time, particles like cholesterols and lipoproteins deposit on the wall of coronary arteries and form plaques. The process is known as atherosclerosis which continues and causes progressive narrowing of blood vessels. The plaque can sometimes rupture which attracts platelets and fibrin leading to thrombosis and blockages. Without blood supply, heart muscles cannot function and begin to die.

 

Symptoms and Diagnosis

Typical symptoms of AMI include chest pain and discomfort, sometimes radiating to jaw and left arm. Other symptoms include sweating and shortness of breath. Atypical symptoms like indigestion and dizziness can also be due to AMI. Sometimes, cardiac arrest may be the first presentation of AMI.

 

Complications of AMI

AMI causes heart muscles to die and fail to function which leads to cardiogenic shock and acute heart failure. Besides, the dying heart muscle can develop arrhythmia or heart structures may rupture which cause cardiac tamponade, acute mitral regurgitation or acute ventricular septal defect. All these conditions are immediate life-threatening and increase the chance of stroke or other organ failure. In long term, due to various degree of heart damage, survivors of AMI are at increased risk of chronic heart failure, arrhythmia and stroke etc.

 

Treatment

Management of AMI mainly includes medications and other measures to restore the blood supply to the heart muscles. You may be given oxygen, intravenous fluids or medications and various monitoring devices to maintain vital parameters such as blood pressure, blood oxygenation and heart rate. Specifically for STEMI, the main aim of treatment is to open up the blocked coronary artery as soon as possible. It can be done by performing Primary Percutaneous Coronary Intervention (PPCI, known as Coronary Angioplasty) which opens up the blocked artery or using Thrombolytic Therapy which lyse the blood clot. You will also be given drugs such as anti-platelet agents or anti-thrombotics to make your blood thinner. Besides, other medications which help heart function or lower blood lipid may also be used. In some case, Coronary Artery Bypass Grafting Surgery (CABG, known as bypass surgery) may be needed.

 

(Source : Hospital Authority Smart Patient)