Myocardial Infarction

During a myocardial infarction the lining of an atheromatous plaque in one of the coronary arteries ruptures . As a result the blood in the artery comes into contact with the lipid rich material of the plaque. This activates the clotting mechanism and just as when skin is cut  blood clots on contact with the air so on contact with the lipid rich material it clots forming a thrombus. This thrombus can block the flow of blood in the artery. As a result the portion of cardiac muscle supplied by the artery is staved of its oxygen supply. If oxygen is cut off for long enough this cardiac muscle dies (myocardial infarction).  A myocardial infarction used to be called a coronary thrombosis. The major symptom of a myocardial infarction is severe and persistent chest discomfort – often felt as crushing or severe tightness.  Unless the supply of blood is rapidly restored some of the cardiac muscle dies – myocardial necrosis. The quicker the supply is restored the less the damage that results.

Treatment of myocardial infarction has changed a lot over the last ten years.  The treatment depends on the results of the electrocardiogram ECG. The results of blood tests such as Troponin may also be taken into account.  For patients with ECG changes showing ST segment elevation the preferred option is now Primary Coronary Intervention (PCI) - Angioplasty usually with insertion of at least one stent . The rationale is to restore coronary blood flow and to keep the reopened coronary artery open.

For patients who do not have ST elevation on the ECG Non ST elevation myocardial infarction often abbreviated to NONSTEMI patients are often initially stabilised with injections of low molecular weight heparin and antipalatelet drugs such as aspirin and clopidogrel.  Drugs such as beta blockers and nitrates are often used during this time. Patients with this form of myocardial infarction often undergo coronary angiography and where suitable coronary angioplasty and stenting within 48 – 72 hours.

Until recently the main treatment of acute myocardial infaction was the administration of clot busting drugs such as streptokinase through a vein. Increasingly patients with ST elevation acute myocardial infarction are being taken immediately to a specialist hospital for immediate angioplasty (Primary Angioplasty). Those with no ST elevation acute myocardial infarction often have angiography and angioplasty after about 48 hours of medical treatment.

If you have concerns about heart attacks and how to avoid them I can answer general questions by email If you would like a private appointment to talk to a specialist then, with the agreement of your GP please feel free to telephone my secretary to book an appointment on 020 8441 2922
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