What is MYOCARDIAL INFRACTION (Heart attack)?

This condition occurs when the oxygen supply to the heart muscle gets shut off because of complete blockage of a coronary artery due to build-up of atherosclerotic plaques inside the lumen of the coronary arteries (with or without thrombosis).

The heart muscle is deprived of oxygen that this particular coronary artery normally supplies to it and this causes this part of the heart muscle to die (infarction.)

Why does this happen and how may it affect the patients health?

Atherosclerotic plaques build up in the blood vessels of all human beings. Men are more severely affected than women.

There are risk factors that increase the likelihood of developing atherosclerosis, such as

• Individuals who have a higher predisposition for atherosclerotic build-up in their coronary arteries, due to familial history
• High blood pressure
• Diabetes mellitus
• High lipid levels in blood
• Smoking
• Type A personality (stress prone)

The blockage of coronary arteries may either be a gradual process that takes place over many years, or it may happen suddenly due to blood clot formation on atheromatous plaques.30% of patients who experience heart attacks die (more than 50% of those who die are already dead on arrival at the hospital).

What symptoms may the patient experience?

The most common symptom is a severe crushing pain that feels like a tight band around the chest; this pain may radiate to the

• Jaw
• Left shoulder
• Left arm (downward)
• Stomach
• Back

The patient experiences

• Sweating
• Fear
• A feeling of impending doom
• Profound weakness

These symptoms may be preceded by episodes of angina pectoris (pain in the chest due to diminished oxygen supply to the heart muscle, which may be relieved by nitroglycerine).

In the event of a heart attack, nitroglycerine will not relieve pain.

The pain is often described as the worst pain the patient has ever experienced. The patient may develop very low blood pressure and the circulation through all the damaged tissues becomes very ineffective. Heart failure and accumulation of fluid within the lungs (pulmonary oedema) may follow.

The patient may also develop shock due to poor and ineffective pumping of blood from the left ventricle; this causes inadequate blood perfusion of tissues. On examination of the heart, the doctor may hear a noise caused by the heart sac (pericardial friction rub; Dressler syndrome).

Myocardial infarction may occur at any time; day or night. Although pain is the most common presenting complaint, it is not always present; older people and diabetics are prone to develop painless infarcts.

Other associated symptoms

• Breathlessness
• State of confusion
• Fever
• Loss of consciousness

How is the diagnosis made and what special investigations are required?

Increased cardiac enzymes in the blood (CK; MB; LDH). ECG shows characteristic changes of a heart attack (Q-waves; ST-segment changes). The various types of heart attacks are identified on ECG through evidence of their unique configuration patterns. Chest X-ray.

What is the treatment and prognosis?

• Emergency CPR during the attack if the patient develops cardiac arrest or if there is insufficient and poor cardiac output.
• Admission to the cardiac care unit of a hospital as soon as possible.
• Management and stabilisation of the acute phase after the attack.
• Aspirin is now considered an essential element in the management of myocardial infarction.
• Administer supplemental oxygen.
• Nitroglycerin under tongue.
• Morphine, in order to control and relieve pain.

Other drugs and treatment modalities include

• Intravenous beta-blockers
• Thrombolytic therapy (dissolves blood clots in coronary arteries) within 30 minutes of onset
• Angioplasty (balloon type catheter device is used to flatten atherosclerotic plaques inside coronary arteries in an attempt to open the channels of the coronaries)

Rehabilitation

Medication to control and improve high cholesterol levels in blood. To prevent recurrent attacks

• Stop smoking
• Follow a sensible healthy diet
• Follow an appropriate exercise program
• Treat high blood pressure if necessary
• Use medications prescribed by a cardiologist
• Cut salt from diet

© 2003 Prometheus™ Healthcare (Pty) Ltd