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BIOT 412 Human Diseases Assignment Maria Maqsood

Department of Biological Sciences

FORMAN CHRISTIAN COLLEGE LAHORE

(A CHARTERED UNIVERSITY)

Assignment: Myocardial Infarction

Name: Maria Maqsood

Roll No: 12-10094

Instructor: Dr. Leslye Johnson

Course: BIOT 412(Medical Biotechnology)


Disease: Myocardial Infarction

1. What is it?

Myocardial infarction is basically known as heart attack and is characterized by the

interruption of supply of blood to a portion of the heart. This causes the heart cells to die and

may result in acute myocardial infarction (AMI). Technically this blockage is in the coronary

arteries, which are involved in the role of supplying blood and oxygen to the heart muscles.

Survival rate varies with the type of blockage.

2. Demographics and Gender Effect of MI

MI is stated to be a clinical problem of essential nature owing to its spread and high mortality

rate. As many as 15.8 million people in the USA during 2004 were affected with MI, and out of

them 450,000 died. As per statistics available since then, as many as 565,000 new cases of MI

are occurring, while 300,000 are recurrent cases. In a developed nation like US, MI and related

conditions (coronary heart disease) kill as many as 157,000 people!

As per the gender argument is concerned, it is wrongfully thought that male are at a higher

risk of MI. The reason is that the risk factors are same for both men and women. In certain cases,

male in family are more affected owing to genetic reasons. A woman’s risk of developing MI at

the age of 50 is as high as 46%. This figure debunks theories that MI is dominant in males.

The occurrence of MI in Pakistan is highly varied and no tangible statistics are there. A

research study carried out in 2006 revealed that cases relating to MI are increasing in South

Asian countries. Much of this is attributed to habits like smoking and high cholesterol diet.

(Saleheen et al., 2009)

3. Cause

As referred to earlier, the reason of myocardial infarction is blockage in the coronary arteries.

Basically it results in the formation of a clot. With the blockage, the supply of oxygen to the

heart is lessened and heart cells begin to die. This clot is also known as plaque. The plaque is a

hard substance that gradually builds up in the coronary arteries. The major composition of this


plaque is cholesterol. It is said that formation of plaque is one of the reasons for MI. The

mechanism can be explained as follows:

The formation of plaque can cause cracks in the arterial cell wall, and platelets would

stick to them. This combination is known as a blood clot, and it is one of the most

common forms of heart attacks. The thickening condition is known as atherosclerosis.

In other cases, the plaque would not cause the formation of cracks. In those cases, it

becomes a gradual process. The plaque keeps on depositing and leads to a heart attack

when amount of oxygen going through lessens. This condition is mostly aggravated by

factors like stress. This can also be seen in the figure below:

3. 1 Factors that Cause it

Since we are discussing MI, we should also know what the factors that can lead to this condition

are:

A) High Blood Cholesterol (Hyperlipidemia)

It is now quite well established that cholesterol is the main component of the plaque that leads to

MI, so high blood cholesterol levels is a dangerous thing to have. Those who had the chance of

going to a cardio hospital or seeing a report would have come across the terms like low density

lipoproteins and high density lipoproteins. Basically lipoproteins are molecules that would assist

in dissolving the cholesterol in blood. The cholesterol that combines with low density


lipoproteins leads to plaque formation and is therefore referred to as “bad cholesterol”. High

density lipoproteins have the effect of removing the plaque, so they are called as “good

cholesterol”.

B) Hypertension

Hypertension or High Blood pressure is another factor that can lead to atherosclerosis and

consequently MI. Reducing hypertension can lessen the chances of a heart attack to a great

degree.

C) Smoking

Smoking cigarettes can lead you closer to a heart attack because the smoke from tobacco inflicts

damage to your blood vessels.\

D) Diabetes Mellitus

Diabetes is another condition that has been linked with increasing the rate of atherosclerosis in

the body. This makes patients of DM at a much higher risk of suffering from stroke than non-

DM ones.

Other factors like lack of exercise, drinking alcohol and sedatory lifestyle also add to the risk of

MI.

4. Symptoms

The most common symptom that occurs is chest pain. Usually, the pain moves from chest to

arms and other areas. A condition known as angina may also result. The patient feels shortness

of breath as well. Apart from this, there is a general discomfort in the upper middle abdominal

region. Sweating is another symptom of myocardial infarction. It is interesting to note that in at

least a quarter of MI happen without any symptoms. This trend has been seen in huge numbers in

patients suffering from diabetes mellitus.

4.1 Aftermath

Due to a MI, a fatal condition that can occur is heart failure. A similar deadly condition is

ventricular fibrillation in which the routine electrical activity of the heart is disrupted leading to


permanent brain damage, if the flow of blood is not restored. The figure provided below sheds

light on three different stages that can happen during a MI. On is the acute stage, followed by a

sub-acute one and finally a healed stage. You can notice the decreasing level of necrosis of heart

muscle in each stage.

5. Genetics of Myocardial Infarction

Now that we have taken at a lot of factors that can lead to MI, it is imperative that we take a

look at the genetic factor as well. Yes, there is a molecular genetic basis of MI. Inherently; it is a

mixture of multiple genes and environmental factors that cause MI. The scope of this genetics

based study is to develop better diagnosis and lower occurrence of MI as well.

Using genome wide association study, it has been unveiled that at least 100 loci are involved

in conditions related to coronary diseases, including MI. These have been labeled as “genetic

susceptibility factors”. (Yamada et al., 2008)

6. Diagnosis of MI

Initial detection of MI can be difficult since there are conditions where there is no tangible

symptom. Routine diagnosis focuses on the principle that MI has occurred, and the purpose is to

know the extent of damage.


A) Electrocardiogram

In all cases, an Electrocardiogram (ECG) is used to know the electrical activity of the heart. In

cases of MI, abnormalities can be seen and areas where oxygen is not going show quite erratic

results. This method works best for people who show symptoms, since prompt response can be

taken in case of a heart attack. For people who show little symptoms, elevation in heart enzymes

is one key diagnosis factor. The figure below shows the ECG in four different stages.

B) Blood Tests and Cardiac Markers

The second mode of diagnosis focuses on blood testing. A heart muscle that is dying would

release enzymes. These enzymes would act as cardiac markers for us, since an elevated level

shows the sign of abnormality in function. Examples of such enzymes include creatine

phosphokinase, subfractions of creatine phosphokinase and troponin. These tests are very

effective in detecting a MI and also showing how much muscle damage has been done. The

troponin test is said to the most sensitive and specific one, when it comes to detecting a MI.

Hence, it is the most used cardiac marker for MI. The graph given below would give you an

analysis on the concentration of these different cardiac markers. As you can see from the graph,

troponin shows maximum sensitivity within a 12 hour period, and acts as a valuable cardiac

marker for detecting MI. (Fauci, 2009)


7. Treatment

The scope of treatment of MI is basically focused on opening the congested artery so that

normal blood flow can be restored. Usage of anti platelet medicine like aspirin is done for

reducing the ability of platelet formation, which can lead to clotting. Such medicines prevent

further blockage too.

In case of MI and condition like angina, nitroglycerin is given, which acts as a vasodilator

and relaxes the muscle. Routinely it is given as a tablet which is kept under the mouth.

Since we discussed the role of enzymes, enzyme inhibitors are also used e.g Angiotensin

converting enzyme. By blocking the enzyme, the blood vessels widen and the healing process is

increased.

A well known mode of treatment is the usage of beta blocking agents which limit the

production of adrenaline. The effect is such that the heart muscles remain in a relaxed position

and are not forced.

Emergency Treatments would include protocols like angioplasty, in which blocked vessels

are opened with the usage of a stent. This procedure has to be performed within an hour and half

of the attack. (Walker & Rapley, 2005)


8. Research Question

Can Stem Cell be an ideal solution?

Researches have shown that stem cell treatment has worked to some extent in patients

with MI conditions. Bone-marrow derived stem cells are said to work best for MI condition. A

research paper on this notion states,

“BMCs injection into the infarcted heart has been shown to enhance neovascularization,

reduce negative remodeling, and improve contractile function, either in animals or in humans. In

fact, there are many clinical trials which have been conducted in order to identify the efficacy

and safety of BMCs therapy in AMI patients”. (Kuswardhani & Soejitno, 2011) The image

below explains the process:


References

Kuswardhani, R.A & Soejitno A.(2011) “Bone Marrow derived Stem cells as an

adjunctive treatment for acute myocardial infarction: a systematic review and meta

analysis” Acta Med Indones 43(3): 168-77

Fauci, AS, Braunwald, E, Kasper DL, Hauser, SL, Longo, DL, Jameson JL, Loscalzo, J.

(2009) Harrison’s Manual Of Medicine. McGraw Hill: New York, 886-888

Saleheen D, Zaidi M, Rasheed A, Ahmad U, Hakeem A, Murtaza M, Kayani W, Faruqui

A, Kundi A, Zaman KS, Yaqoob Z, Cheema LA, Samad A, Rasheed SZ, Mallick NH,

Azhar M, Jooma R, Gardezi AR, Memon N, Ghaffar A, Fazal-ur-Rehman, Khan N, Shah

N, Ali Shah A, Samuel M, Hanif F, Yameen M, Naz S, Sultana A, Nazir A, Raza S,

Shazad M, Nasim S, Javed MA, Ali SS, Jafree M, Nisar MI, Daood MS, Hussain A,

Sarwar N, Kamal A, Deloukas P, Ishaq M, Frossard P, Danesh J., (2009) “ The Pakistan

risk of Myocardial Infarction Study” Eur J Epidemiol 24(6): 329-38

Walker, JM & Rapley R. (2005) Medical Biomethods Handbook, Humana Press: New

York. 105

Yamada, Y, Ichihara, S & Nishida, T (2008) “Molecular genetics of Myocardial

Infarction” Genomic Med 2(1): 7-22

For figures:

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001246/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001246/

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