Angina Pectoris

Angina pectoris is a clinical syndrome characterized by discomfort in the chest, jaw, shoulder, back, or arm. These symptoms are common presenting symptoms among patients with coronary artery disease particularly chest pain. It is one of the most common symptoms of ischemic heart disease (IHD). It occurs when there is an imbalance between myocardial oxygen supply and demand.

Types

There are four main types of angina pectoris,

1.       Stable angina

2.       Unstable angina

3.       Prinzmetal angina/variant or vasospastic angina

4.       Microvascular angina

Stable angina

In this type, chest discomfort occurs due to transient myocardial ischemia with physical exertion. That increases the oxygen demand of the body. It is usually relieved within minutes by rest or by sublingual nitroglycerin. It usually lasts within 5 minutes or less.

Unstable angina

It is due to decrease in coronary blood flow leading to insufficient oxygen supply to the heart muscles. This insufficient supply is due to narrowing of arteries as a result of fatty buildups. It usually lasts for more than 20 minutes or is relieved by taking a rest.

Prinzmetal angina (variant / vasospastic angina)

It occurs as a result of coronary artery spasm in which the artery temporarily narrows. As a result of this narrowing, the blood supply to the heart is reduced.

Microvascular angina

It occurs when small vessels in the heart become narrow and stop functioning normally.

Causes

Atherosclerosis is the major reason behind ischemic heart disease. Atherosclerosis is a condition in which fatty substance or cholesterol builds up inside the blood vessels. These builds up are called plaques. They can block blood flow through vessels partially or completely. Angina pectoris is also caused by pulmonary embolism (a blockage in a lung artery), pericarditis (Inflammation in the heart tissues) and aortic dissection (tear in the wall of the major artery carrying blood out of the heart). Angina pectoris occurs as a result of myocardial ischemia. Myocardial ischemia is caused by an imbalance between myocardial blood supply and oxygen demand. Approximately 50% of patients with atherosclerosis develop myocardial ischemia. It can also occur as a result of reduced oxygen-carrying capacity of blood due to anemia.

Risk factors

1.                    Age

2.                    High blood pressure

3.                    High blood cholesterol

4.                    Stress

5.                    Lack of exercise

6.                    Tobacco use

Symptoms

Most of the patients with angina pectoris reports chest pain & discomfort. This discomfort is retrosternal rather than frank. Retrosternal chest pain can be described as a pressure, heaviness, and squeezing, burning, or choking sensation. This pain may be localized primarily in the epigastrium, back, neck, jaw, or shoulders. The most common locations for anginal pain are shoulders, arms and neck. If the chest pain lasts for about a few seconds then it is not anginal pain. Pain above the lower jaw and below the epigastric region is rarely anginal in nature. Anginal pain lasts for about 1-5 minutes. This pain is relieved by taking rest or nitroglycerin.

Treatment

The standard treatment plan for the treatment of angina pectoris includes,

1.                   Nitrates

2.                   Beta blockers

3.                   Calcium channel blockers

4.                   Sodium channel blockers

5.                   ACE inhibitors

6.                   Antiplatelet agents

Nitrates

They provide relief from angina symptoms by causing a reduction in myocardial oxygen demand. They are effective in stable, unstable, and variant angina. There are two types of nitrates, short acting and long acting nitrates. Short acting nitrates are the first line treatment for angina pectoris. They terminate acute episodes of angina. Drugs include nitroglycerine at the dose of 0.3-0.4 mg. Long acting nitrates are preferred for patients with more frequent angina attacks. For these attacks, long acting anti-anginal therapy is required. Drugs included are isosorbide mononitrate, isosorbide dinitrate and long acting nitroglycerine.

Beta blockers

They decrease the myocardium oxygen demand by blocking β1receptors. As a result, a decrease occurs in heart rate, contractility, cardiac output and blood pressure. They can also reduce oxygen demand even during rest or exertion. Drugs included are atenolol, bisoprolol, metoprolol, pindolol and propranolol.

Calcium channels blockers

 They protect the heart tissue by inhibiting the entry of calcium into cardiac and smooth muscles. All calcium channels blockers are arteriolar vasodilators. They cause a decrease in smooth muscle tone and peripheral vascular resistance. CCBs reduce oxygen demand of myocardium by lowering wall pressure and cardiac contractility. CCBs are recommended as initial treatment in ischemic heart diseases when beta blockers are contraindicated. There are two main types of calcium channel blockers, dihydropyridines and non dihydropyridines. Dihydropyridines include amlodipine, felodipine and nifedipine. Non dihydropyridine calcium channel blockers include diltiazem and verapamil.

Sodium channels blockers

The exact mechanism of action of sodium channels blockers is still not known. They are effective in the treatment of chronic angina. The most commonly used sodium channel blocker is ranolazine and it is used at the dose of 750-2000mg twice daily.

Antiplatelet agents

They are shown to reduce the risk of major adverse cardiac events particularly myocardial infarction. They are considered as cardio protective agents. They are used in stable and unstable angina. Aspirin is the commonly used antiplatelet agent and it is used at the dose of 75- 325mg.

Angiotensin-converting enzyme (ACE) inhibitors

They reduce the risk of vascular events in patients with chronic stable angina. Drugs included are captopril, fosinopril and ramipril.

Surgical treatment

There are different surgical treatments available for angina pectoris such as,

1.                   Percutaneous coronary intervention (previously called Angioplasty/stenting)

2.                   CABG (Coronary Artery Bypass Graft Surgery