Studying Microcirculation Structure and Function

Microcirculation Structure and Function
The microcirculation is comprised of arterioles, capillaries, venules, and terminal lymphatic vessels.

Arterioles
· Small precapillary resistance vessels (10-50 µ) composed of an endothelium surrounded by one or more layers of smooth muscle cells.
· Richly innervated by sympathetic adrenergic fibers and highly responsive to sympathetic vasoconstriction via both a 1 and a 2 postjunctional receptors.
· Represent a major site for regulating systemic vascular resistance.
· Rhythmical contraction and relaxation of arterioles sometimes occurs (i.e., spontaneous vasomotion).
· Primary function within an organ is flow regulation, thereby determining oxygen delivery and the washout of metabolic by-products.
· Regulate, in part, capillary hydrostatic pressure and therefore influence capillary fluid exchange.

Capillaries
· Small exchange vessels (6-10 µ) composed of highly attenuated (very thin) endothelial cells surrounded by basement membrane – no smooth muscle.
· Three structural classifications:
Continuous (found in muscle, skin, lung, central nervous system) – basement membrane is continuous and intercellular clefts are tight (i.e., have tight junctions); these capillaries have the lowest permeability. Fenestrated (found in exocrine glands, renal glomeruli, intestinal mucosa) – perforations (fenestrae) in endothelium result in relatively high permeability.

Discontinuous (found in liver, spleen, bone marrow) – large intercellular gaps and gaps in basement membrane result in extremely high permeability.

· Large surface area and relatively high permeability (especially at intercellular clefts) to fluid and macromolecules make capillaries the primary site of exchange for fluid, electrolytes, gases, and macromolecules.
· In some organs, precapillary sphincters (a circular band of smooth muscle at entrance to capillary) can regulate the number of perfused capillaries.

Venules
· Small exchange vessels (10-50 µ) composed of endothelial cells surrounded by basement membrane (smallest postcapillary venules) and smooth muscle (larger venules).
· Fluid and macromolecular exchange occur most prominently at venular junctions.
· Sympathetic innervation of larger venules can alter venular tone which plays a role in regulating capillary hydrostatic pressure.

Terminal Lymphatics
· Composed of endothelium with intercellular gaps surrounded by highly permeable basement membrane and are similar in size to venules – terminal lymphatics end as blind sacs.
· Larger lymphatics also have smooth muscle cells.
· Spontaneous and stretch-activated vasomotion is present which serves to "pump" lymph.
· Sympathetic nerves can modulate vasomotion and cause contraction.
· One-way valves direct lymph away from the tissue and eventually back into the systemic circulation via the thoracic duct and subclavian veins (2-4 liters/day returned).

Understanding ANASTOMOSIS and COLLATERAL CIRCULATION

CIRCULATORY ANASTOMOSIS

Arteries do not always end in capillarie; in many cases they unite with one another, forming what are called anastomosis

Anastomoses occur normally in the body in the circulatory system, serving as backup routes for blood to flow if one link is blocked or otherwise compromised. There are many examples of these in the body. However clinically important examples include:
Circle of Willis (in the brain)
scapular anastomosis (for the subclavian vessels)
joint anastomoses - clinically very important. Almost all joints receive anastomotic blood supply from more than one source. Examples include knee (and geniculate arteries), shoulder (and circumflex humeral), hip (and circumflex iliac) and ankle.
pelvic anastomoses
abdominal anastomoses
hand and foot anastomoses (which include the palmar and plantar arches)
Coronary: anterior and posterior interventricular ries of the heart circle of Willis

Coronary anastomoses are a clinically vital subject:

The coronary anastomosis is the blood supply to the heart. The coronary arteries are vulnerable to arteriosclerosis and other effects. Inadequate supply to the heart will lead to chest pains (angina) or a heart attack (myocardial infarction).
Coronary anastomoses are anatomically present though functionally obsolete. There was some suggestion that they may be helpful if a problem develops slowly over time (this will need to be verified) but in the case of the pathogenesis of CHD(coronary heart disease) they do not provide a sufficient blood flow to prevent infarction.
There are anastomoses between the Circumflex and right coronary arteries and between the anterior and posterior inter-ventricular arteries. In the normal heart these anastomoses are non-functional.

Collateral Circulation

What is collateral circulation?
This is a process in which small (normally closed) arteries open up and connect two larger arteries or different parts of the same artery. They can serve as alternate routes of blood supply.
Everyone has collateral vessels, at least in microscopic form. These vessels normally aren't open. However, they grow and enlarge in some people with coronary heart disease or other blood vessel disease (such as in the case of stroke). While everyone has collateral vessels, they don't open in all people.

How does collateral circulation help people with heart disease?
When a collateral vessel on the heart enlarges, it lets blood flow from an open coronary artery to an adjacent one or further downstream on the same artery. In this way, collateral vessels grow and form a kind of "detour" around a blockage. This collateral circulation provides alternate routes of blood flow to the heart in cases when the heart isn't getting the blood supply it needed

How does collateral circulation help people with stroke?
When an artery in the brain is blocked due to stroke or transient ischemic attack (TIA), open collateral vessels can (but not always) allow blood to "detour" around the blockage. This collateral circulation restores blood flow to the affected part of the brain. However, not all people can develop “collateral circulation,” so prevention of heart disease and stroke should always be the gold standard.

Understanding MICROCIRCULATION

MICROCIRCULATION

What is microcirculation?

First of all, what is blood circulation?

The circulation can be pictured as blood travelling through the body in blood vessels. On average, we have about 5 litres of blood travelling through our circulatory system, delivering oxygen and nutrients to all parts of the body. On its return route to the heart, the blood picks up carbon dioxide and waste products to be excreted. Arteries carry blood away from the heart, in large volume and under high pressure.

Smaller arteries branching off are called arterioles and eventually lead to capillaries. Capillaries are the tiniest of our blood vessels. Being small allows them to penetrate into every corner of the body, bringing oxygen and nutrients to the tissues and single cells. Blood in the capillaries feeds the tissues before travelling away from tissue and organs, flowing into small veins called venules and then into larger veins carrying blood back to the heart.

Microcirculation is the vascular network lying between the arterioles and the venules, including capillaries, as well as the flow of blood through this network. Or in other words:
Microcirculation is the link between blood and single cell. By this link, tissue and single cells are supplied
with oxygen and nutrients.

The importance of microcirculation:
A better supply of blood and therefore oxygen and nutrients to a cell means:
The cell functions better;▼The organ works better;▼All organs work better;▼The whole organism works better;▼Result: A person feels and is healthier!N

Understanding CIRCULATION

BLOOD CIRCULATION
General Pulmonary Circulation Systematic Circulation Hepatic Portal System Circulation Coronary Circulation

General.
The blood system of vertebrates is a closed system, i.e. the blood vessels are not open -ended. In the organs the arteries divide to form arterioles (small arteries) which in turn divide to form numerous capillaries. The capillaries unite to form larger vessels, called the venules (small veins). The venules leave the tissues and join with other venules to form veins. Veins leave the organs and eventually join the venae cavae. It is thus clear that the arterial and venous blood link up by means of capillaries in the tissues.
In this section we will discuss the main circulatory system.

Pulmonary Circulation.
The pulmonary artery arises from the right ventricle and tranports deoxygenated blood (oxygen-poor) to the lungs, where the blood becomes oxygenated again. The four pulmonary veins return the oxygenated blood (oxygen-rich) to the left atrium of the heart. The pulmonary circulation is also referred to as the lesser circulation. The summary of the pulmonary circulation is thus:
Right Ventricle - pulmonary artery - lungs - pulmonary veins - left atrium - left ventricle.

Systemic Circulation.
Oxygenated blood is pumped from the left ventricle into the aorta. Branches of the aorta convey blood to all the tissues and organs of the body (except the lungs). The tissue cells are oxygenated and deoxygenated blood returned to the heart via the superior and inferior venae cavae. The blood then flows via the tricuspid valve into the right ventricle, from where it joins the pulmonary circulation. The systemic circulation is also referred to as the greater circulation. The summary of the systemic circulation is thus:
Left ventricle - aorta - organs - venae cavae - right atrium - left ventricle.

The Hepatic Portal System of Circulation.
This system serves the intestines, spleen, pancreas and gall bladder. The liver receives it blood from two main sources. The main sources are the hepatic artery, which as a branch of the aorta, supplies oxygenated blood to the liver and the hepatic portal vein, which is formed by the union of veins from the spleen, the stomach, pancreas, duodenum and the colon. The hepatic portal vein transports, inter alia, the following blood to the liver:
absorbed nutrients from the duodenum;
white blood cells (added to the circulation) from the spleen;
poisomous substances, such as alcohol which are absorbed in the intestines, and
waste products, such as carbon dioxide from the spleen, pancreas, stomach and duodenum.
The hepatic artery and hepatic portal vein open into the liver sinuses where the blood is in direct contact with the liver cells. The deoxygenated blood, which still retains some dissolved nutrients, eventually flows into the inferior vena cava via the hepatic veins.Coronary Circulation.
This circulation supplies the heart muscle itself with oxygen and nutrients and conveys carbon dioxide and other waste products away from the heart. Two coronary arteries lead from the aorta to the heart wall, where they branch off and enter the heart muscle. The blood is returned from the heart muscle to the right atrium through the coronary vein, which enters the right atrium through the coronary sinus.

Undertanding STROKE

STROKE

A stroke is an interruption of the blood supply to any part of the brain. A stroke is sometimes called a "brain attack. A blood vessel carrying blood to the brain is blocked by a blood clot. This is called an ischemic stroke.(>80 %)
A blood vessel breaks open, causing blood to leak into the brain. This is a hemorrhagic stroke(<20 %)
If blood flow is stopped for longer than a few seconds, the brain cannot get blood and oxygen. Brain cells can die, causing permanent damage.

ISCHEMIC STROKE

This is the most common type of stroke. Usually this type of stroke results from clogged arteries, a condition called atherosclerosis. Fatty deposits collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. Often, the plaque causes the blood to flow abnormally, which can cause the blood to clot. There are two types of clots:
A clot that stays in place in the brain is called a cerebral thrombus.

(A moving thrombus is an embolus)

A clot that breaks loose and moves through the bloodstream to the brain is called a cerebral embolism.
Another important cause of cerebral embolisms is a type of arrhythmia called atrial fibrillation.
Other causes of ischemic stroke include endocarditis, an abnormal heart valve, and having a mechanical heart valve. A clot can form on a heart valve, break off, and travel to the brain. For this reason, those with mechanical or abnormal heart valves often must take blood thinner
HEMORRHAGIC STROKE
A second major cause of stroke is bleeding in the brain. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.

Intracerebral hemorrhage occurs when a diseased blood vessel within the brain bursts, allowing blood to leak inside the brain. (The name means within the cerebrum, or brain). The sudden increase in pressure within the brain can cause damage to the brain cells surrounding the blood. If the amount of blood increases rapidly, the sudden buildup in pressure can lead to unconsciousness or death. Intracerebral hemorrhage usually occurs in selected parts of the brain, including the basal ganglia, cerebellum, brainstem, or cortex.
What causes it? The most common cause of intracerebral hemorrhage is high blood pressure (hypertension). Since high blood pressure by itself often causes no symptoms, many people with intracranial hemorrhage are not aware that they have high blood pressure, or that it needs to be treated. Less common causes of intracerebral hemorrhage include trauma, infections, tumors, blood clotting deficiencies, and abnormalities in blood vessels (such as Arterioveinous Malformation or AVM). A ruptured blood vessel will leak blood into the brain, eventually causing the brain to compress due to the added amount of edema

Subarachnoid Hemorrhage
When a cerebral aneurysm ruptures, blood will fill the space surrounding the brain.
What is it? Subarachnoid hemorrhage occurs when a blood vessel just outside the brain ruptures. The area of the skull surrounding the brain (the subarachnoid space) rapidly fills with blood. A patient with subarachnoid hemorrhage may have a sudden, intense headache, neck pain, and nausea or vomiting. Sometimes this is described as the worst headache of one's life. The sudden buildup of pressure outside the brain may also cause rapid loss of consciousness or death.
What causes it? Subarachnoid hemorrhage is most often caused by abnormalities of the arteries at the base of the brain, called cerebral aneurysms. These are small areas of rounded or irregular swellings in the arteries. Where the swelling is most severe, the blood vessel wall become weak and prone to rupture. urgical treatment of aneurysms involves placing clip on neck of aneurysm.
Who gets it? The cause of cerebral aneurysms is not known. They may develop from birth or in childhood and grow very slowly. Some people have not one, but several aneuryms. Subarachnoid hemorrhage can occur at any age, including teenagers and young adults. Subarachnoid hemorrhage is slightly more common in women than men.

STROKE RISKS

High blood pressure is the number one reason that you might have a stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.

Certain medications increase the chances of clot formation, and therefore your chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.

Men have more strokes than women. But, women have a risk of stroke during pregnancy and the weeks immediately after pregnancy.

Cocaine use, alcohol abuse, head injury, and bleeding disorders increase the risk of bleeding into the brain.

Symptoms »

The symptoms of stroke depend on what part of the brain is damaged. In some cases, a person may not even be aware that he or she has had a stroke.

Usually, a SUDDEN development of one or more of the following indicates a stroke:

Weakness or paralysis of an arm, leg, side of the face, or any part of the body

Numbness, tingling, decreased sensation

Vision changes

Slurred speech, inability to speak or understand speech, difficulty reading or writing

Swallowing difficulties or drooling

Loss of memory

Vertigo (spinning sensation)

Loss of balance or coordination

Personality changes

Mood changes (depression, apathy)

Drowsiness, lethargy, or loss of consciousness

Uncontrollable eye movements or eyelid drooping

If one or more of these symptoms is present for less than 24 hours, it may be a transient ischemic attack (TIA). A TIA is a temporary loss of brain function and a warning sign for a possible future stroke

Exams and Tests »

In diagnosing a stroke, knowing how the symptoms developed is important. The symptoms may be severe at the beginning of the stroke, or they may progress or fluctuate for the first day or two (stroke in evolution). Once there is no further deterioration, the stroke is considered completed.

During the exam, your doctor will look for specific neurologic, motor, and sensory deficits. These often correspond closely to the location of the injury in the brain. An examination may show changes in vision or visual fields, abnormal reflexes, abnormal eye movements, muscle weakness, decreased sensation, and other changes. A "bruit" (an abnormal sound heard with the stethoscope) may be heard over the carotid arteries of the neck. There may be signs of atrial fibrillation.

Tests are performed to determine the type, location, and cause of the stroke and to rule out other disorders that may be responsible for the symptoms. These tests include:

Head CT or head MRI -- used to determine if the stroke was caused by bleeding (hemorrhage) or other lesions and to define the location and extent of the stroke.

ECG (electrocardiogram) -- used to diagnose underlying heart disorders.

Echocardiogram -- used if the cause may be an embolus (blood clot) from the heart.

Carotid duplex (a type of ultrasound) -- used if the cause may be carotid artery stenosis (narrowing of the major blood vessels supplying blood to the brain).

Heart monitor -- worn while in the hospital or as an outpatient to determine if a heart arrhythmia (like atrial fibrillation) may be responsible for your stroke.

Cerebral (head) angiography -- may be done so that the doctor can identify the blood vessel responsible for the stroke. Mainly used if surgery is being considered.

Blood work may be done to exclude immune conditions or abnormal clotting of the blood that can lead to clot formation.

CT scan- well established stroke

Treatment

A stroke is a medical emergency. Physicians have begun to call it a "brain attack" to stress that getting treatment immediately can save lives and reduce disability. Treatment varies, depending on the severity and cause of the stroke. For virtually all strokes, hospitalization is required, possibly including intensive care and life support.
The goal is to get the person to the emergency room immediately, determine if he or she is having a bleeding stroke or a stroke from a blood clot, and start therapy -- all within 3 hours of when the stroke began.

IMMEDIATE TREATMENT
Thrombolytic medicine, such as tPA, breaks up blood clots and can restore blood flow to the damaged area. People who receive this medicine are more likely to have less long-term impairment. However, there are strict criteria for who can receive thrombolytics. The most important is that the person be examined and treated by a specialized stroke team within 3 hours of when the symptoms start. If the stroke is caused by bleeding rather than clotting, this treatment can make the damage worse -- so care is needed to diagnose the cause before giving treatment.
In other circumstances, blood thinners such as heparin and Coumadin are used to treat strokes. Aspirin may also be used.
Other medications may be needed to control associated symptoms. Pain killers may be needed to control severe headache. Medicine may be needed to control high blood pressure.
Nutrients and fluids may be necessary, especially if the person has swallowing difficulties. The nutrients and fluids may be given through an intravenous tube (IV) or a feeding tube in the stomach (gastrostomy tube). Swallowing difficulties may be temporary or permanent.
For hemorrhagic stroke, surgery is often required to remove pooled blood from the brain and to repair damaged blood vessels.

LONG-TERM TREATMENT
The goal of long-term treatment is to recover as much function as possible and prevent future strokes. Depending on the symptoms, rehabilitation includes speech therapy, occupational therapy, and physical therapy. The recovery time differs from person to person.
Certain therapies, such as repositioning and range-of-motion exercises, are intended to prevent complications related to stroke, like infections and bed sores. People should stay active within their physical limitations. Sometimes, urinary catheterization or bladder/bowel control programs may be needed to control incontinence.
The person's safety must be considered. Some people with stroke appear to have no awareness of their surroundings on the affected side. Others show indifference or lack of judgment, which increases the need for safety precautions. For these people, friends and family members should repeatedly reinforce important information, like name, age, date, time, and where they live, to help the person stay oriented.
Caregivers may need to show the person pictures, repeatedly demonstrate how to perform tasks, or use other communication strategies, depending on the type and extent of the language problems.
In-home care, boarding homes, adult day care, or convalescent homes may be required to provide a safe environment, control aggressive or agitated behavior, and meet medical needs.
Behavior modification may be helpful for some people in controlling unacceptable or dangerous behaviors.
Family counseling may help in coping with the changes required for home care. Visiting nurses or aides, volunteer services, homemakers, adult protective services, and other community resources may be helpful.

Outlook (Prognosis)
The long-term outcome from a stroke depends on the extent of damage to the brain, the presence of any associated medical problems, and the likelihood of recurring strokes.
Of those who survive a stroke, many have long-term disabilities, but about 10% of those who have had a stroke recover most or all function. Fifty percent are able to be at home with medical assistance while 40% become residents of a long-term care facility like a nursing home.
Possible Complications
Problems due to loss of mobility (joint contractures, pressure sores)
Permanent loss of movement or sensation of a part of the body
Bone fractures
Muscle spasticity
Permanent loss of brain functions
Reduced communication or social interaction
Reduced ability to function or care for self
Decreased life span
Side effects of medications
Aspiration
Malnutrition

Prevention of a Stroke:
The risk of stroke may be reduced with a healthy diet, control of high blood pressure, regular exercise, and by avoiding or quitting smoking. Follow your health care provider's recommendations for the treatment and prevention of heart disease. Forty percent of patients who have had a stroke or TIA will suffer a subsequent stroke within 5 years.
Quit Smoking
Smoking is a major risk factor for stroke. Patients should also avoid exposure to second-hand smoke. Many organizations recommend asking patients at every visit about smoking. Smoking is a chronic condition and often requires repeat therapy using more than one cessation technique.
Control Diabetes
People with diabetes should aim for fasting blood glucose levels of less than 110 mg/dl and hemoglobin A1C of less than 7%. Blood pressure goals should be 130/80 mm Hg or less.
Antiplatelet and Anticoagulant Medications for Preventing Stroke
Antiplatelet Drugs
Blood platelets are involved in blood clotting. Antiplatelets prevent clotting by blocking the activation of platelets. An antiplatelet drug -- most often aspirin -- is given within 48 hours of an ischemic stroke and continued in low doses as maintenance therapy. Some studies suggest that antiplatelet therapy can reduce the risk for a second stroke by 25%
Primary Prevention (to prevent a stroke from occurring)
People at high risk for heart disease should take a low-dose aspirin every day, unless they have medical reasons to avoid aspirin. (As an alternative to aspirin alone, your doctor may prescribe clopidogrel (Plavix 75mg) alone or aspirin plus extended release dipyridamole.) Aspirin may help to prevent strokes caused by blockage in the artery (ischemic stroke), but it may slightly increase the risk of strokes caused by bleeding in the brain (hemorrhagic stroke).
The American Heart Association recommends aspirin therapy (75 - 325 mg/day) for women over age 65 who are at risk for stroke. Women over age 65 who are at lower risk for stroke may consider taking aspirin every other day.
Aspirin therapy strictly to prevent strokes is not recommended for men who do not have heart disease.
Some younger patients with atrial fibrillation, or those for whom anticoagulants such as warfarin are not safe, are treated with aspirin 100mg or clopidogrel 75mg.

Secondary Prevention (to prevent another stroke after one has occurred).
Aspirin combined with sustained release dipyridamole in a fixed-dose combination given twice daily is often prescribed to prevent another stroke. Aspirin is not recommended when uncontrolled hypertension is present. Clopidogrel may be used if aspirin cannot be taken but it is not better than aspirin. Combining aspirin and clopidogrel together does not have any more benefit and increases the risk for another stroke.
Anticoagulant Drugs. Warfarin (Coumadin) is the main anticoagulant (“blood thinner”) drug used to prevent strokes in high-risk patients with atrial fibrillation. Warfarin carries a risk for bleeding, but for most patients, warfarin’s benefits far outweigh its risks. The risk for bleeding is highest when warfarin therapy is first started, with higher doses, and with long periods of treatment. Patients at risk for bleeding are usually older and have a history of stomach bleeding and high blood pressure. It is important that patients who take warfarin have their blood checked regularly to make sure that it does not become “too thin.” Blood that is too thin increases the risk for bleeding, while blood that is “too thick” increases the risk for blood clots and stroke. Prothrombin time (PT) and international normalized ratio (INR) tests are used to monitor blood coagulation.
People with atrial fibrillation, who are generally considered candidates for warfarin therapy, often have one or more of the following characteristics:
History of blood clots to the lungs, stroke, or transient ischemic attack
Have a blood clot in one of their heart chambers
Significant valvular heart disease
High blood pressure
Diabetes, with age older than 65 years
Left atrium (one of the chambers of the heart) is enlarged
Coronary artery disease
Heart failure
Diet and Weight Control
No randomized controlled trials have studied a direct relationship between diet and stroke. However, the relationship between diet and heart disease, unhealthy cholesterol and lipids, and high blood pressure seems to indicate that dietary recommendations for these disorders also may help prevent stroke. A healthy diet rich in fruits and vegetables and low in salt and saturated fats may significantly lower the risk for both ischemic and hemorrhagic stroke. For diet plans, the Mediterranean diet may be a particularly good choice for reducing the risk of stroke.

Some evidence suggests that diets rich in potassium may protect against stroke, mostly by reducing blood pressure but also possibly because of other mechanisms. Low potassium levels may increase the risk for stroke in certain people.
Salt Restriction. Although the effects of salt restriction are not entirely clear, a diet with less than or equal to 2,300 mg of sodium per day is recommended. (Restriction to 1,500 mg/day is recommended for middle-aged people and those with high blood pressure.)

Vitamins
Folic Acid and B Vitamins. Deficiencies in the B vitamins folate (known also as folic acid), B6, and B12 have been associated with a higher risk for heart disease in some studies. Such deficiencies produce higher blood levels of homocysteine, an amino acid that has been associated with a higher risk for heart disease, stroke, and heart failure. Researchers have been studying whether vitamin B supplements can reduce homocysteine levels and, consequently, heart disease risks.
Recent studies have indicated that while B vitamin supplements help lower homocysteine levels, they have no effect on heart disease outcomes. In studies, patients who have either recently had a heart attack or suffer from diabetes or heart disease show a similar number of heart attacks and strokes whether they took folic acid and B6 and B12 vitamins or received placebo. The vitamins seem to increase risks for patients who have a stent in their bodies. Some experts think that homocysteine may be a marker for heart disease rather than a cause of it. Newer approaches specifically designed for stroke patients are being evaluated.
Antioxidant Vitamins.
The effects of antioxidant vitamins and carotenoids (vitamins C or E, or beta carotene) on stroke have been studied extensively. Most studies have found that these vitamins do not help protect against stroke.
Alcohol and Caffeine
Alcohol. Mild-to-moderate alcohol use (one to seven drinks a week) is associated with a significantly lower risk for ischemic stroke, although not hemorrhagic stroke. Heavy alcohol use, particularly a recent history of drinking, is associated with a higher risk of both ischemic and hemorrhagic stroke.

Coffee.
In healthy people with normal blood pressure, drinking a couple of cups of coffee a day is unlikely to do any harm. Caffeine may actually have nerve-protecting properties that may help stroke survivors. Caffeine drinkers, however, might consider choosing tea, which may have beneficial nutrients, and people with existing hypertension should avoid caffeine altogether (since caffeine may increase the risk for stroke in this group).
Exercise
Exercise helps reduce the risk of atherosclerosis, which can help reduce the risk of stroke. Experts recommend at least 30 minutes of exercise on most, if not all, days of the week.
Hypertension is a disorder characterized by chronically high blood pressure. It must be monitored, treated, and controlled by medication, lifestyle changes, or a combination of both.
Reducing Blood Pressure
Reducing blood pressure is essential in stroke prevention. Lifestyle measures such as exercise, weight loss, and healthy diets are important for everyone. Drug therapy is recommended for people with hypertension who cannot control their blood pressure through lifestyle changes. Many different types of drugs are used to control blood pressure. They include ACE inhibitors, angiotensin-receptor blockers, beta-blockers, calcium andchannel blockers.

Risk Groups
Blood Pressure Stages (Systolic/Diastolic)
Prehypertension
(120 - 139/80 - 89)
Mild (Stage 1) Blood Pressure
(140 - 159/90 - 99)
Moderate-to-Severe (Stage 2) Blood Pressure
(Systolic pressure over 160 or diastolic pressure over 100)

Risk Group A
Have no risk factors for heart disease.
Lifestyle changes only. (Exercise and dietary program with regular monitoring.)
Year trial of lifestyle changes only. If blood pressure is not lower at 1 year, add drug treatments.
Lifestyle changes and medications.

Risk Group B
Have at least one risk factor for heart disease* (excluding diabetes) but have no target organ damage (such as in the kidneys, eyes, or heart, or existing heart disease).
Lifestyle changes only.
6-month trial of lifestyle changes only. If blood pressure is not lower at 6 months, add drug treatments.
Medications considered for patients with multiple risk factors.
Lifestyle changes and medications.

Risk Group C
Have diabetes with or without target organ damage and existing heart disease (with or without risk factors for heart disease).
Lifestyle changes and medications.
Lifestyle changes and medications.
Lifestyle changes and medications. Risk factors for heart disease include the following: family history of heart disease, smoking, unhealthy cholesterol and lipid levels, diabetes, being over 60 years old.

Lowering LDL and Raising HDL Cholesterol
In 2004, the National Cholesterol Education Program issued updated recommendations on how to control cholesterol levels. These guidelines emphasize that patients should lower their LDL (“bad”) cholesterol and recommend that more people take LDL-lowering medication. Lowering LDL cholesterol and raising HDL (“good”) cholesterol can significantly reduce the risks of heart disease, including stroke.
The doctor will start or consider medication, increase dosage of medication, or add new medication when:
LDL cholesterol is 190 mg/dL (5 mmol/l) or higher.
LDL cholesterol is 160 mg/dL (4 mmol/l) or higher AND patient has one risk factor for heart disease.
LDL cholesterol is 130 mg/dL (3.3 mmol?l)or higher AND patient has either diabetes or two other risk factors for heart disease.
LDL cholesterol is 100 mg/dL (2.6 mmol/l) or higher AND patient has heart disease or any other form of atherosclerosis. (If patient has diabetes, even without heart disease, medication may be considered for an LDL cholesterol of 100 mg/dL.)
LDL cholesterol is greater than 70 mg/dL (1.8 mmol/l)AND patient has had a recent heart attack or has known heart disease along with diabetes, current cigarette smoking, poorly controlled high blood pressure, or the metabolic syndrome (high triglycerides, low HDL, and obesity).

Risk factors for heart disease include:
Having a first-degree female relative diagnosed with heart disease before age 65 or a first-degree male relative diagnosed before age 55
Being male and over age 45 or female and over age 55
Cigarette smoking
Diabetes
High blood pressure
Metabolic syndrome (risk factors associated with obesity such as low HDL levels and high triglycerides)
Statins have become the most important LDL-lowering drugs. Brands include lovastatin 20,40 mg (Mevacor), pravastatin 20,40 mg (Pravachol), simvastatin 10,20,40,80 mg(Zocor), fluvastatin 20,40,80 mg(Lescol), atorvastatin 10,20,40,80 mg(Lipitor), and rosuvastatin 5,10,20 mg(Crestor). Research increasingly suggests that lowering LDL levels as much as possible is critical for preventing stroke and other heart disease problems. Analysis of data from many studies indicate that statins reduced the risk for heart problems by 60% and stroke by 17 - 25%.
Statins are proven to reduce the risk of ischemic stroke in people at increased risk for heart disease. (However, statins can increase the risk for the less-common hemorrhagic type of stroke.) Research suggests that they may also prevent stroke in patients without heart disease. However, current guidelines recommend that statins should be prescribed to patients without heart disease or high LDL (“bad” cholesterol) levels only if diabetes or other heart disease risk factors are also present.
Researchers are also investigating whether statins might be beneficial in preventing a second stroke in patients who have suffered a stroke or transient ischemic attack (TIA). Recent studies indicate that high-dose statin therapy may help reduce the risk of stroke recurrence and other heart events for patients who have had a prior stroke or TI
Atrial Fibrillation and Its Treatments
As discussed previously, patients with chronic or recurrent atrial fibrillation are treated with aspirin or warfarin) to prevent clots from forming. Attempts to restore or maintain normal heart rhythm may be attempted with anti-arrhythmic drugs, cardioversion procedures, or surgery to remove the defective area. However, recurrent episodes of atrial fibrillation often occur. Simply controlling the heart rate is increasingly considered the preferable approach for many patients.

Understanding Thrombolytic Drug

Thrombolytics
Thrombolytic therapy is the use of drugs to break-up the clot that is causing the disruption in blood flow to the brain.
It is crucial, imperative, and very important that you immediately go to the hospital when you first notice the warning signs of a stroke. The length of time between the first warning signs and the time you get to a hospital may be the difference between a good or poor outcome. Patients who present to the hospital within 3 hours of the first sign of a stroke have the possibility to receive alteplase (tPa, Activase®). Alteplase is a clot-buster. It breaks-up the clot to restore blood flow to the area of the stroke.
There are many factors that determine whether or not a patient is able to receive thrombolytic therapy. One of these factors, that you have control of, is the amount of time between the onset of symptoms and presentation to the hospital. If you get to the hospital within the 3 hour time frame and the doctor determines you are able to receive this clot-buster, you may have a better recovery.
Tissue Plasminogen Activator(tPA, Activase®)
Tissue plasminogen activator is a thrombolytic drug (a "clot-buster"). It can reduce the severity of ischemic stroke if it is given within three hours of stroke onset. This drug can be given intravenously or by arterial catheter, but not by mouth.

Understanding MYOCARDIAL INFARCTION

Coronary Heart Diseases - Heart attack/myocardial infarction

There are 2 arteries supplying the heart; the right and the left coronary artery. RCA splits into a marginal branch which feeds blood to the right ventricle and the posterior interventricular branch, which supplies the left ventricle. The LCA is a larger artery. It splits into the anterior interventicular branch( anterior descending) and circumflex branch.

The coronary arteries are very vulnerable to blockage and narrowing through a process of ATHEROSCLEROSIS which can cause a depletion of blood to a certain part of the heart, possibly causing ischaemic heart diseases and heart attach

Myocardial Infarction (Heart Attack)
Myocardial infarction (MI) is usually caused by a blood clot that stops blood flow in a heart (coronary) artery. Call for an ambulance immediately if you develop severe chest pain. Treatment with a 'clot busting' drug or an emergency procedure to restore blood flow through the blocked artery are usually done as soon as possible to prevent damage to heart muscle. Other treatments help to ease the pain and prevent complications. Reducing risk factors can help to prevent ischaemic heart disease

What is Myocardial Infarction?
Myocardial infarction (MI) means that part of the heart muscle suddenly loses its blood supply. Without prompt treatment, this can lead to damage to the affected part of the heart. An MI is sometimes called a heart attack or a coronary thrombosis. An MI is part of a range or disorders called 'acute coronary syndromes'.

Understanding the heart and coronary arteries:
The heart is mainly made of special muscle. The heart pumps blood into arteries (blood vessels) which take the blood to every part of the body.Like any other muscle, the heart muscle needs a good blood supply. The coronary arteries take blood to the heart muscle. The main coronary arteries branch off from the aorta. (The aorta is the large artery which takes oxygen-rich blood from the heart chambers to the body.) The main coronary arteries divide into smaller branches which take blood to all parts of the heart muscle

What happens when you have a myocardial infarction?
If you have an MI, a coronary artery or one of its smaller branches is suddenly blocked. The part of the heart muscle supplied by this artery loses its blood (and oxygen) supply. This part of the heart muscle is at risk of dying unless the blockage is quickly undone. (The word 'infarction' means death of some tissue due to a blocked artery which stops blood from getting past.)If one of the main coronary arteries is blocked, a large part of the heart muscle is affected. If a smaller branch artery is blocked, a smaller amount of heart muscle is affected. In people who survive an MI, the part of the heart muscle that dies ('infarcts') is replaced by scar tissue over the next few weeks

What causes myocardial infarction?

Thrombosis - the cause in most cases of infarction.
The common cause of an MI is a blood clot (thrombosis) that form inside a coronary artery, or one of its branches. This blocks the blood flow to a part of the heart.Blood clots do not usually form in normal arteries. However, a clot may form if there is some atheroma within the lining of the artery. Atheroma is like fatty patches or 'plaques' that develop within the inside lining of arteries. (This is similar to water pipes that get 'furred up'.) Plaques of atheroma may gradually form over a number of years in one or more places in the coronary arteries. Each plaque has an outer firm shell with a soft inner fatty core.What happens is that a 'crack' develops in the outer shell of the atheroma plaque. This is called 'plaque rupture'. This exposes the softer inner core of the plaque to blood. This can trigger the clotting mechanism in the blood to form a blood clot. Therefore, a build up of atheroma is the root problem that leads to most cases of MI. (The diagram above shows four patches of atheroma as an example. However, atheroma may develop in any section of the coronary arteries.)Treatment with 'clot busting' drugs or a procedure called angioplasty (see below) can break up the clot and restore blood flow through the artery. If treatment is given quickly enough this prevents damage to the heart muscle, or limits the extent of the damage.
Uncommon causes
Various other uncommon conditions can block a coronary artery and cause an MI. For example: inflammation of the coronary arteries (rare); a stab wound to the heart; a blood clot forming elsewhere in the body (for example, in a heart chamber) and travelling to a coronary artery where it gets stuck; cocaine abuse which can cause a coronary artery to go into spasm; complications from heart surgery; and some other rare heart problems. There are not dealt with further.The rest of this leaflet deals only with the common cause - thrombosis over an atheroma

Who has a myocardial infarction?
MI is common. About 180,000 people in the UK are admitted to hospital each year with an MI. Most MIs occur in people over 50, and become more common with increasing age. Sometimes younger people are affected. An MI is three times more common in men than women. An MI may occur in people known to have heart disease such as angina. It can also happen 'out of the blue' in people with no previous symptoms of heart disease. (Atheroma often develops without any symptoms at first.)

What are the symptoms of a myocardial infarction?
Severe chest pain is the usual main symptom. The pain may also travel up into your jaw, and down your left arm, or down both arms. You may also sweat, feel sick, and feel faint. The pain may be similar to angina, but it is usually more severe and lasts longer. (Angina usually goes off after a few minutes. MI pain usually lasts more than 15 minutes - sometimes several hours.)A small MI occasionally happens without causing pain (a 'silent MI'). It may be truly pain-free, or sometimes the pain is mild and you may think it is just heartburn or 'wind'.Some people collapse and die suddenly if they have a large or severe MI.

What should I do if I suspect I am having a myocardial infarction?
Call for an ambulance immediately. Then, if you have some, take one aspirin tablet (see below for the reason for this). You will normally be admitted straight to hospital.

How is myocardial infarction diagnosed and assessed?
Many people develop chest pains that are not due to an MI. For example, you can have quite bad chest pains with heartburn, gallbladder problems, or with pains from conditions of the muscles in the chest wall. However, tests can usually confirm MI. These are:
A heart tracing called an ECG (electrocardiograph). There are typical changes to the normal pattern of the heart tracing if you have an MI. Patterns that occur with an MI include things called 'pathological Q waves' and 'ST elevation'. However, it is possible to have a normal ECG even if you have had a severe MI
Blood tests. A blood test that measures a chemical called troponin is the usual test that confirms an MI. This chemical is present in heart muscle cells and damage to heart muscle cells releases troponin into the bloodstream. The blood level of troponin increases within 3-12 hours from the onset of chest pain, peaks at 24-48 hours, and returns to a normal level over 5-14 days.
A rough idea as to the severity of the MI (the amount of heart muscle that is damaged) can be gauged by the degree of abnormality of the ECG and the level of troponin in the blood. Another chemical that may be measured in a blood test is called creatinine kinase. This too is released from heart muscle cells during an MI.Your heart tracing will be monitored for a few days to check on the heart rhythm. Various blood tests will be done to check on your general well- being.Other tests may be done in some cases. This may be to clarify the diagnosis (if the diagnosis is not certain) or to diagnose complications such as heart failure if this is suspected. For example, an echocardiogram (an ultrasound scan of the heart) or a test called myocardial perfusion scintigraphy may be done.Also, before discharge from hospital, you may be advised to have tests to assess the severity of atheroma in the coronary arteries. For example, an ECG taken whilst you exercise on a treadmill or bike ('exercise-ECG'). Or, angiography of the coronary arteries. In this test a dye is injected into the coronary arteries. The dye can be seen by special X-ray equipment. This shows up the structure of the arteries (like a road map) and can show the location and severity of any atheroma.

What is the treatment for myocardial infarction?
The following is a 'typical' situation and mentions the common treatments offered. Each case is different and treatments may vary depending on your situation
Aspirin and other anti-platelet drugs
As soon as possible after an MI is suspected you will be given a dose of aspirin. Aspirin reduces the 'stickiness' of platelets. Platelets are tiny particles in the blood that trigger the blood to clot. It is the platelets that become stuck onto a patch of atheroma inside an artery that go on to form the clot (thrombosis) of an MI. Another anti-platelet drug called clopidogrel is also usually given as soon as possible. This works in a different way to aspirin and adds to the action of reducing platelet stickiness. In Malaysia, a popular clopidogrel is Plavix 75mg
Pain relief
A strong pain killer given by injection into a vein will ease the pain such Morphine.
Treatment to restore blood flow in the blocked coronary artery
The part of the heart muscle starved of blood does not die ('infarct') immediately. If blood flow is restored within a few hours, much of the heart muscle that would have been damaged will survive. This is why an MI is a medical emergency, and treatment is given urgently. The quicker the blood flow is restored, the better the outlook. There are two treatments that can be done to restore blood flow back through the blocked artery.Emergency angioplasty is, ideally, the best treatment if it is available and can be done within a few hours of symptoms starting. In this procedure a tiny wire with a balloon at the end is put into a large artery in the groin or arm. It is then passed up to the heart and into the blocked section of a coronary artery using special x-ray guidance. The balloon is blown up inside the blocked part of the artery to open it wide again. A stent may be left in the widened section of the artery. A stent is like a wire mesh tube which gives support to the artery and helps to keep the artery widened. An injection of a 'clot busting' drug is an alternative to emergency angioplasty. In reality, this is the more common treatment as it can be given easily and quickly in most situations. Some ambulance crews are trained to give this treatment. Note: the common 'clot buster' drug used in the UK is called streptokinase. If you are given this drug you should not be given it again if you have another MI in the future. This is because antibodies develop to it and it will not work so well a second time. An alternative 'clot buster' drug should be given if you have another MI in the future.Both the above treatments usually work well to restore blood flow and greatly improve the outlook. The most crucial factor is the quickness in which one or other treatment is given after symptoms have developed.




Injection of heparin or a similar drug
These are usually given for a few days to help prevent further blood clots

Treatment after you have had a myocardial infarction:
Once you have had an MI, you will normally be advised to take regular medication for the rest of your life. After a Myocardial Infarction, briefly the following four drugs are commonly prescribed to prevent a further MI, and to help prevent complications.

Aspirin300mg - to reduce the 'stickiness' of platelets in the blood which helps to prevent blood clots forming. If you are not be able to take aspirin then an alternative anti-platelet drug such as clopidogrel (Pravix 75mg)may be advised.

A beta-blocker - to slow the heart rate, and to reduce the chance of abnormal heart rhythms developing.
An ACE inhibitor (angiotensin converting enzyme inhibitor). ACE inhibitors have a number of actions including having a protective effect on the heart. In Malaysia, popular ones are

Coversyl 4mg,8mg and Catapril 12.5mg,25mg,50mg
A statin drug to lower the cholesterol level in your blood. This helps to prevent the build-up of atheroma.
Also, you will normally be advised to take the anti-platelet drug clopidogrel in addition to aspirin. However, this is usually only advised for a certain number of weeks or months, depending on the type and severity of the MI.Many people recover well from an MI and have no complications. Before discharge from hospital it is common for a doctor or nurse to advise you how to reduce any risk factors (see below). This advice aims to reduce your risk of a future MI as much as possible.Other drugs or treatments may be needed if you develop complications. For example, treatments for heart failure may be needed if you develop heart failure as a complication after an MI

How serious is a myocardial infarction?
This often depends on the amount of heart muscle that is damaged. In many cases only a small part of the heart muscle is damaged (infarcts or dies) which heals as a small patch of scar tissue. The heart can usually function normally with a small patch of scar tissue. A larger MI is more likely to be life-threatening or cause complications.Even before treatments became available to restore blood flow such as 'clot busting' drugs and angioplasty, many people made a full recovery as many MIs are small. With the help of modern treatment, particularly if you are given treatment within a few hours to restore blood flow, a higher percentage of people now make a full recovery.Some possible complications that may occur after an MI include the following.

Heart failure. If a large area of the heart muscle is damaged, then the pumping ability of the heart may be reduced. Less blood than usual is then pumped around the body, especially when extra blood is needed when you exercise. Symptoms such as breathlessness, tiredness, and swollen ankles may develop. Mild heart failure can often be treated with medication. Severe heart failure can be serious and life-threatening.

Abnormal heart rhythms may occur if the electrical activity of the heart is affected. The main risk of this happening is within the first few hours after an MI. Sudden, chaotic, fast heart beats may occur. This is called ventricular fibrillation and is the common cause of 'cardiac arrest'. This needs immediate treatment with an electrical shock given by a defibrillator. Otherwise, collapse and sudden death is likely.

A further MI may occur sometime in the future. This is more likely if the coronary arteries are badly affected with atheroma, or further build up of atheroma continues. If the risk of this is thought to be high then surgery may be advised to bypass or widen severely narrowed coronary arteries.
The most crucial time is during the first day or so. If no complications arise, and you are well after a couple weeks, then you have a good chance of making a full recovery. A main objective then is to get back into normal life, and to minimise the risk of a further MI

After having a myocardial infarction.
After recovering from an MI, it is natural to wonder if there are any 'dos and don'ts'. In the past, well-meaning but bad advice to "rest and take it easy from now on" caused some people to become over-anxious about their hearts. Some people gave up their jobs, hobbies, and any activity that caused exertion for fear of 'straining the heart'.However, quite the opposite is true for most people who recover from an MI. Regular exercise and getting back to normal work and life is usually advised. Much can be done to reduce the risk of a further MI. Everybody has a risk of developing atheroma which can lead to an MI. However, certain 'risk factors' increase the risk and include:

Preventable or treatable risk factors:
-smoking
-hypertension (high blood pressure)
-high cholesterol level
-lack of exercise
-a poor diet
-obesity
-excess alcohol
-Having diabetes. But if you have diabetes, the increased risk of heart disease is minimised by good control of the blood sugar level, and reducing blood pressure if it is high.
-Risk factors that are fixed and you cannot change:
a family history of heart disease or a stroke that occurred in a father or brother aged below 55, or in a mother or sister aged below 65
-being male.
-ethnic group (for example, British Asians have an increased risk)
Briefly, if you can reduce any risk factors, it reduces your risk of having an MI (or of having a further MI if you have already had one). Some risk factors are fixed and you cannot change them. However, if you have a fixed risk factor, you may want to make extra effort to reduce preventable risk factors such as smoking or lack of exercise.

What is 'acute coronary syndrome'?
The term 'acute coronary syndrome' is a term that is used more and more by doctors. It covers a range of disorders (including MI) that are caused by the same underlying problem.The underlying problem is a sudden reduction of blood flow to part of the heart muscle. This is caused by a blood clot that forms on a patch of atheroma within a coronary artery (which is described earlier). If the blood clot causes a reduced blood flow, but not a total blockage then the heart muscle supplied by the affected artery does not infarct (die). This situation causes 'acute coronary syndrome with unstable angina' - and typically leads to a sudden worsening of angina pains. If there is death of heart tissue then this is called an 'acute coronary syndrome with MI' (the subject of this leaflet). There is a third 'in between' category where just a very small amount of heart tissue infarcts. This is called 'acute coronary syndrome with myocyte necrosis'. In effect, this is like having a mild MI.One test that is used to distinguish between these three acute coronary syndromes is the blood test for troponin. This test is described earlier. If the level of troponin is normal, then there is no death of heart tissue. If the level is high, then it is classed as an MI. If there is just a slight rise in the level of troponin then this diagnoses 'acute coronary syndrome with myocyte necrosis.

Note from contributer: Complementary herbal medicines are proven to assist in improving 4 areas in prevention, treatment of ischaemic heart diseases and secondary prevention of further myocardial infarction. These herbs can be taken along with western medicine.

These 4 areas are :-

(1) Help preventing atherosclerosis.

(2) Enhance anti-platelet activity of blood to prevent clotting.

(3) Enhance thrombolytic activity of blood to prevent thrombosis.

(3) Improve angiogenesis (produce new vessels). Help establishment of collateral circulation during ischaemic crisis

For further information, please contact the contributer

Understanding THROMBOEMBOLISM

THROMBOEMBOLISM
IN THROMBOEMBOLIM, THE THROMBUS(BLOOD CLOT) FROM A BLOOD VESSEL IS COMPLETELY OR PARTIALLY DETACHED FROM THE SITE OF THROMBOSIS(CLOT). THE BLLOD FLOW WILLTHENCARRY THE THROMBUS TO VARIOUS PART OF THE BODY WHERE IT CAN BLOCK THE LUMEN AND CAUSES VESSEL OCCLUSION.

A FREE MOVING IS CALLED AN EMBOLUS

Understanding EMBOLISM

EMBOLISM

AN EMBOLUS IS A BLOOD CLOT, FAT, AIR, PUS, TISSUE, FOREIGN BODY OR AMNIOTIC FLUID THAT MOVES FROM ONE PART OF THE BODY AND CAUSE A BLOCKAGE(OCCLUSION) OF A BLOOD VESSEL IN ANOTHER PART OF THE BODY.

IT DIFFERS FROM THE THROMBUS AS IT IS FREE MOVING IN THE BLOOD FLOW .