Cannabidiol is a phytocannabinoid derived from the Cannabis sativa plant. This extract is diluted with a carrier oil such as hemp seed oil to form the CBD oil.
CBD belongs to the class of compounds called cannabinoids because it binds to receptors of the endocannabinoid system which mediates several physiological responses.
CBD oil has been proven to have several health benefits as it relieves a variety of ailments. 
Overview of Myocardial Infarction and Ischaemic-Reperfusion Injury
Myocardial infarction (MI) or heart attack occurs when blood flow decreases due to a clot in the coronary arteries which deliver blood and oxygen to the heart.
As blood flow ceases, the heart muscle is damaged due to the lack of oxygen (ischaemia).
The symptoms are chest pain and discomfort, similar to heartburn. 
Ischaemic reperfusion injury is the tissue damage caused by the return of blood supply after ischaemia. 
Benefits of CBD in Myocardial Infarction and Ischaemic-Reperfusion injury
The major benefits of using CBD for the treatment of myocardial infarction and ischaemic-reperfusion injury are linked to its anti-inflammatory, anti-oxidative, and analgesic properties.
CBD lowers the inflammatory response caused due to a heart attack and also counteracts the inflammatory damage caused by atherosclerosis and reperfusion injury.
As the generation of free radicals and oxidative damage to the cardiac tissue is quite common in a reperfused myocardium, CBD usage helps in treating such injuries.
It also prevents the development of aneurysms and helps in healing the cardiac tissue without scarring. CBD also relieves chest pain and lowers blood pressure.
1. CBD Exhibits Anti-Inflammatory & Antioxidant Properties
Myocardial infarction (heart attack) has been linked to an inflammatory response which is required for the healing of the cardiac tissue as well as scar formation, following a period of ischaemia (lack of blood supply).
Blockages in the coronary artery can lead to ischemia which, if prolonged, induces an infarction that is generally associated with inflammation when the blood supply s restore (reperfusion injury). 
Even when the artery occlusion (blockage) occurs for a very short period, functional abnormalities of the reperfused myocardium can last for a matter of days.
This abnormality is usually associated with oxidative damage brought about by the generation of oxygen-free radicals, which along with inflammation, affect cardiac tissue following an infarction. 
Inflammatory damage was first associated with myocardial ischaemia and infarction after a 1973 experimental study that was published in the Journal of Clinical Investigation.
It was found that administration of anti-inflammatory corticosteroids helped in reducing infarct volumes in the canine models. 
However, further research has shown that while anti-inflammatory and antioxidative agents can help in reducing the intensity of infarctions, they also interfere with the process of wound healing and tissue repair by suppressing the inflammatory response and preventing collagen deposition. 
In the 21st century, cannabinoids have emerged as potential therapeutic strategies for treating inflammation and oxidative stress in case of heart attacks.
A 2011 review by The University of Mississippi Medical Center established the role of CBD in attenuating the stress caused by inflammation and free radicals on the recovering myocardium while promoting tissue repair post ischaemia. 
Summary – CBD and its products lower the persistent inflammatory and oxidative stress on the reperfused myocardium following a heart attack and help in promoting the health of the cardiac tissue.
2. CBD Reduces Atherosclerosis
Atherosclerosis denotes a condition wherein the arterial lumen gets narrowed due to the deposition of plaque.
While there are no symptoms in the initial phase, it acts as a precursor for ischaemic heart disease, particularly infarctions.
In severe cases, it can lead to coronary artery occlusion and aortic stenosis which cause stroke, heart attack, and even renal diseases. The symptoms are generally negligible till middle age. 
The risk factors for arterial plaque formation includes high low-density lipoprotein (LDL) cholesterol levels, hyperglycaemia, hypertension, obesity as well external factors like smoking, unhealthy diet, and alcohol abuse.
Prior family history of atherosclerosis also increases the likelihood of developing this disease. 
The plaque is generally constituted by cholesterol, triglycerides, or minerals like calcium.
The narrowing of the blood vessels restricts the supply of blood to various tissues which, in turn, staunch the supply of oxygen resulting in ischaemic conditions.
Once apoptosis and tissue necrosis become dominant, infarction occurs. If such arterial stenosis occurs in the coronary heart, the damage to the myocardium causes a heart attack or failure. 
Therefore, preventing atherosclerosis helps in protecting the heart from infarction and reperfusion injury.
The most common ways to restrict the formation of plaque are by exercising, consuming a nutritious diet, not smoking, and maintaining a healthy weight.
Treatment usually encompasses blood pressure medication, cholesterol-lowering statins, and blood thinners. 
Recently, studies have shown that cannabinoids like CBD are potential medications for treating cardiovascular disorders.
A 2007 review by the Instituto de Investigaciones Farmacológicas revealed that that cannabinoids help in preventing the progression of atherosclerosis and lowering the rate of plaque formations.
This is possible as the endocannabinoid receptors are intimately involved in the functioning of the vascular system. 
Summary – CBD helps in preventing the progression of atherosclerosis and protects the arteries from plaque formation. As a result, it has a cardioprotective effect and reduces the risk of infarction and reperfusion injury.
3. CBD Accelerates Healing After Heart Attack
Following a heart attack, an aneurysm might form in the left ventricle of the heart which is the main pumping chamber.
This occurs after the trauma when the artery is weakened resulting in a localized spot which bulges outward.
If the patient still suffers from high blood pressure, such aneurysms might rupture and the consequences can be fatal.
These conditions act as complications which stunt the healing process after an infarction. 
Another complication arises when a damaged section of the heart grows thinner and weaker. Scarring of the myocardium occurs and the heart wall becomes extremely thin.
This can also lead to a ventricular aneurysm which increases pressure on the heart to work harder to pump blood throughout the body. 
Such ventricular aneurysms may cause chest pain, shortness of breath, and cardiac arrhythmia. However, in more severe cases, they might lead to congestive heart failure and left ventricular heart failure.
Barring aneurysms, reperfusion insult or reoxygenation injury is another complication that is associated with infarctions.
Increased supply of oxygen following ischaemia leads to inflammatory and oxidative damage. 
Several studies have shown that cannabinoids like CBD help in relieving chest pain and inflammatory responses following a myocardial infarction.
A 2013 review by the University of Nottingham revealed that CBD has a great cardioprotective potential and it helps in accelerating the healing process post-infarction.
It also prevents the risk of developing aneurysms and arrhythmias. 
Summary – As CBD helps in preventing the development of aneurysms and reperfusion injury after an infarction, it helps in healing the myocardium after an attack.
4. CBD Reduces Pressure on Arteries
One of the leading causes of myocardial infarction is hypertension or increased pressure against the arterial walls.
Studies have shown that blood pressure is often raised due to the phenomenon of vasoconstriction.
This happens when the muscular wall of the arteries contracts resulting in arterial stenosis (narrowing of the blood vessel). 
Upon constriction, the blood flow encounters resistance and becomes restricted which increases body heat.
One of the physical manifestations of vasoconstriction is the yellowing (paleness) of the skin as less blood reaches the surface to retain body heat. 
120/80 mm of Hg is regarded by medical practitioners to be the normal blood pressure.
Hypertension occurs when the blood pressure is higher than average often as a consequence of persistent vasoconstriction.
Studies have shown that a malfunction in the renin-angiotensin-aldosterone (RAAS) system might lead to this condition. 
When the blood flow to the kidneys gets restricted, the hormone, renin, is released into circulation which prompts a series of reactions to form angiotensin II which is responsible for vasoconstriction.
It also stimulates the release of aldosterone, a hormone that facilitates the reabsorption of sodium.
Sodium retention increases fluid in the vascular system which, along with vasoconstriction, raises the arterial pressure. 
Therefore, in order to lower the pressure on the arteries, vasodilation must be attained. This phenomenon denotes the widening the arterial lumen to facilitate blood flow.
Most drugs prescribed to lower hypertension are vasodilators that relax the arteries and ease the flow of blood. 
A 2017 randomized placebo-controlled study by the Oxford University Hospitals NHS Trust evaluated the role of the phytocannabinoid CBD as a potential vasodilator.
The results showed that the administration of CBD in a dose-dependent manner helped in markedly lowering the resting blood pressure (BP) as well as stress-induced BP by relaxing the arterial lumen (vasodilation). 
Summary – As plant-derived cannabinoids like CBD help in widening the arterial walls and relieving the pressure against the arteries, they prevent the risk of infarctions or reperfusion insult.
5. CBD Protects from Myocardial Ischaemic Reperfusion Injury
Myocardial ischemia-reperfusion injury (IRI) or reoxygenation injury denotes a condition wherein tissue damage is caused by the restoration (re-perfusion) of blood supply to the myocardium following a period of ischaemia or inadequate supply of blood resulting in hypoxia (low oxygen supply).
The reintroduction of oxygen leads to an inflammatory response accompanied by oxidative damage. 
Reperfusion insult results in vascular injury, particularly in the arterioles and capillaries.
This happens due to the sudden increase in the permeability of the blood vessels that dampens vascular resistance to compensate for the earlier period of ischaemia.
Subsequently, the diffusion rate of blood across the cardiac tissues gets abnormally amplified causing damage. Lowered nitric oxide levels cause inflammation. 
Studies have shown that inflammation aggravates the condition. Immune cells circulating in the vascular system detect tissue damage and secrete a host of pro-inflammatory factors like cytokines and oxygen-free radicals.
The reperfused blood causes oxidative damage by rupturing the cell membranes and releasing the intracellular contents. 
IRI is the concluding part of the heart’s ischaemic cascade which is preceded by an infarction brought about by coronary artery occlusion.
This series of traumatic cardiovascular events can severely damage the myocardium and therefore, controlling and reversing them are dynamic areas of interest in medical research.
Frequent instances of infarction and IRI could lead to permanent inflammation and cardiac arrest. 
A 2010 animal study by the Robert Gordon University evaluated the cardioprotective role of CBD in preventing the damage caused by IRI.
The results established that acute administration of CBD in male Sprague-Dawley rats lowered ischaemia-induced cardiac arrhythmias (irregular heartbeat) and reperfusion injury by improving response to oxidative stress and lowering inflammation. 
Summary – As CBD helps in reducing cardiac arrhythmias and inflammatory responses, it helps in protecting the heart from myocardial ischaemia-reperfusion injury.
It is always recommended to consult a medical practitioner before using medication containing THC.
The dosage depends on the mode of delivery as the CBD products can be orally ingested or inhaled by a vaporizer.
There is no prescribed dose for using CBD to treat myocardial infarction and ischaemic-reperfusion injury. This is because different individuals have different tolerance capacities.
It is usually recommended to begin with small doses of around 50-60mg per day and continue increasing the dosage until an optimal effect is observed.
Vaporizers containing CBD oil can be used to relieve short-term symptoms such as chest pain and 6-8mg should be inhaled to have a good effect.
The plant-derived cannabinoid, CBD, has very few known side-effects. In fact, daily oral doses of up to 500mg can be had for a period of 6 months.
According to a 2011 review, even high doses of almost 1500mg can be tolerated, regularly, for up to 3 months. 
The majority of the CBD products contain varying amounts of the psychotropic agent, tetrahydrocannabinol (THC) which is responsible for some of the side-effects.
Although the quantity of THC is quite harmless and cannot produce a substantial effect, some individuals might be sensitive and hence, it is recommended to begin with small doses. 
CBD often inhibits the activity of a class of liver enzymes (cytochrome p450) which metabolize certain drugs and hence, CBD usage might affect drug efficacies.
Excess-THC containing products might cause dizziness, confusion, disorientation, nausea, fatigue, impaired balance, hallucinations, and even paranoia. 
THC might also increase the heart rate for a short duration and this condition is known as tachycardia. Cannabis products containing high amounts of THC should also not be accompanied by alcohol. 
Pregnant and lactating women are particularly recommended to consult a gynecologist before consuming CBD products.
Caution should also be maintained while administering THC-containing products to children and adolescents as it might affect their CNS differently. 
To summarize, it can be said that CBD confers several cardiovascular benefits that help in both the prevention and treatment of myocardial infarction and reperfusion injury.
It lowers inflammation and oxidative damage which are the two markers of ischaemia and reoxygenation insult.
Due to its anti-inflammatory nature, it also prevents the progression of atherosclerosis and the development of plaques.
CBD also helps in preventing hypertension which is one of the major precursors for coronary heart disease.
By protecting the heart from aneurysms after an infarction, CBD also helps in stimulating the healing process.
Finally, it prevents ischemia-reperfusion injury by eliminating cardiac arrhythmias and promoting the normal flow of blood.