When blood flow to the heart is compromised, a series of biochemical changes occur due to a lack of oxygen. These changes culminate in a distinct type of chest pain we term angina. It’s imperative to understand it for several reasons: (1) several causes of chest pain may mimic it. (2) it is the most pertinent symptom of ischaemic heart disease that causes significant morbidity and mortality. Angina can either be stable, unstable, or prinzmetal. In this article, we help you understand the science behind chest pain that signals a heart problem.
Globally, ischaemic heart disease remains one of the top ten causes of mortality. Angina, the most common symptom, is chest pain that arises as the blood vessels supplying the heart (coronary arteries) narrow to impede blood flow to the heart. The narrowing may be due to a blockage due to fatty deposits (atherosclerosis) or vessel spasms.
It’s prudent to differentiate the various types of angina. Stable angina is chest pain that occurs due to exertion and resolves at rest. In unstable angina, the pain occurs even at rest. Variant (prinzmetal) angina also occurs at rest. It is due to vasospasm (spasms of the coronary arteries with a transient stagnation in blood flow to the heart). For each, treatment may be different.
Without a doubt, atherosclerosis (fatty deposits in the coronary arteries) is the most common cause of angina; however, anaemia, cardiac arrhythmias (abnormal heart rhythms), and vasospasms also cause angina.
Essential to recognise are the causes of chest pain that may mimic angina. Some are cardiac, for example, myocarditis and pericarditis. Others are non-cardiac, i.e., hiatus hernia, gastroesophageal reflux disease, and peptic ulcer disease: pneumothorax, pulmonary embolism, and pneumonia: rib injury, muscle spasms, and costochondritis: panic attack, anxiety, and aortic dissection.
Angina affects more men than women. The risk increases with age and family history of coronary artery disease: high blood cholesterol, hypertension, obesity, and diabetes.
How does angina develop? The heart relies on oxygen to respire (produce energy) and contract. Any perturbance in the oxygen supply to the heart muscle enables anaerobic respiration. During the process, lactic acid is the by-product instead of carbon dioxide and water. The cells also discharge potassium and hydrogen ions into the internal milieu. Under normal circumstances, (1) there’s more potassium inside the cells than outside. (2) calcium is the principal ion that directs muscle contraction. The hydrogen ions compete with calcium ions to slow or stop heart muscle contraction. These biochemical changes lead to chest pain.
Typically, angina presents as retrosternal (behind the sternum) heaviness (tightness) that radiates (spreads) to the jaw, neck, back, left shoulder, or left arm. At times, it may feel like heartburn. Associated symptoms may include sweating, nausea, dizziness, syncope, and shortness of breath. Chest pain may be sudden or slow in onset: its relation to exercise and rest or relief with nitroglycerin determine whether it is stable or unstable angina. The patient may not have any pertinent signs on physical examination.
A high index of suspicion is crucial to making a diagnosis. Tests like an electrocardiogram (ECG), complete blood count, lipid profiles, chest x-ray, and cardiac enzymes (in particular troponin levels) are crucial add-ons. When the tests show any blockage in the coronary arteries, cardiac catheterisation becomes necessary.
Because the aim is to restore blood flow to the heart, several treatment strategies exist to enable this to happen – both pharmacological and surgical. Initially, the patient must calm down to rest. Medications pertinent to angina include nitrates (nitroglycerin), morphine, beta-blockers, antiplatelet agents, and anticoagulants. It is imperative to note that nitrates and morphine provide no mortality benefit. Any blockage not amenable to medical therapy may warrant surgery – angioplasty, stenting, or coronary artery bypass graft.
It is necessary to change the lifestyle for a better living. It involves smoking cessation, weight control, healthy dieting, and exercise. Keep hypertension, high blood cholesterol, and diabetes at bay.
Angina, if untreated, may culminate in myocardial infarction, heart failure, and diminished quality of life.
In a nutshell, weight control, a healthy diet, exercise, and smoking cessation will drastically reduce your risk of angina. You are in control of your destiny. Any chest pain that doesn’t resolve with nitroglycerin at home warrants an urgent call to your doctor or a visit to the hospital. Adhere to any medications as prescribed by your clinician and inquire about anything that doesn’t add up.