The golden hour of a heart attack

Cardiologist, Dr YT Singh, educates us on why and how a heart attack occurs and the importance of getting to a hospital within the golden hour.

How does the heart function?

To function, heart muscle needs an energy supply of oxygenated blood via three major coronary arteries: left anterior descending (LAD), right coronary artery and circumflex.

At any time, demand for energy by the heart muscle and supply to heart muscle by those three arteries must equate: demand must equal supply. 

If there is any imbalance in this equation: for instance, increased demand for energy by the heart muscle (manifest by fast heart rate, thickened heart muscle) or reduced supply to the heart muscle by the arteries (manifest as a blockage), it will result in impaired heart muscle function.

What is angina?

If there is partial blockage of the arteries supplying the heart muscle with blood, this will manifest as angina in the form of chest pain, jaw pain, arm pain, sometimes abdominal pain or a combination of these. 

Anginal pain is usually temporary, subsiding after resting or with medication, like glyceryl trinitrate (TNT). The pain settles when demand and supply balance. Angina doesn’t result in permanent damage to heart muscle but is a warning sign of an impending heart attack. 

How is the pain felt?

The sensation of pain varies. It can be a dull chest ache or a feeling of pressure. It can also manifest as chest burn, often mistaken for peptic ulcer disease or gastric reflux. Beware of chest burn that isn’t relieved with antacids. 

Diabetic patients often don’t present with chest pain or sensation of pressure, and may describe shortness of breath on exertion, rather than chest pain.

How does a heart attack happen?

A heart attack is caused in most cases by a clot that blocks one of the coronary arteries supplying the heart muscle with blood. The clot is usually caused by a plaque of cholesterol rupturing, spilling its contents into the artery, mixing with the blood and forming a clot, which obstructs blood flow to the heart muscle, causing damage.

Permanent damage to the heart muscle isn’t immediate but is time dependent. The critical time is 60 minutes after the heart muscle stops receiving blood flow. The heart will be permanently damaged after four hours with no blood flow to the muscle.

The golden hour of a heart attack

The critical period in which to prevent permanent damage to the heart muscle is one hour: the golden hour. For an optimal result and to prevent permanent heart muscle damage, coronary artery flow must be re-established within an hour of the presentation of chest pain.

How can the clot be removed?

The clot can be dissolved pharmacologically or mechanically. Pharmacologic therapy involves injecting the patient intravenously with a clot-busting agent known as a thrombolytic. Mechanical management is more effective than pharmacologic but entails the patient being admitted to a hospital with cardiac catheterisation facilities, where urgent coronary angiography can be undertaken by a specialist cardiologist and heart care team. The blocked artery is opened with an angioplasty balloon and the narrowed segment of artery stented.

How to get treatment in the golden hour

1. Don’t delay in seeking medical help when presenting with chest pain or an equivalent sensation. Be particularly suspicious of a cardiac problem if you have risk factors, like diabetes, hypertension, smoking, high cholesterol or strong family history of heart attacks or strokes.
2. Try to get to a hospital with specialised cardiac facilities. Get to know where such specialised hospitals are located close to your home, and make sure family members know this, as well. 
3. Ascertain beforehand whether your medical aid or plan type allows you to be admitted to the cardiac unit closest to your home.
4. If no specialised cardiac units are near your home, get to know where the nearest district hospital is located, so that at least thrombolytic therapy can be administered without delay. 

Header image by Freepik