Stroke

What is a stroke?

Brain cell function requires a constant delivery of oxygen and glucose from the bloodstream. A stroke, or cerebrovascular accident (CVA), occurs when blood supply to part of the brain is disrupted, causing brain cells to die. Blood flow can be compromised by a variety of mechanisms.

Blockage of an artery

• Narrowing of the small arteries within the brain can cause a lacunar stroke, (lacune means "empty space"). Blockage of a single arteriole can affect a tiny area of brain causing that tissue to die (infarct).
  
  
• Hardening of the arteries (atherosclerosis) leading to the brain. There are four major blood vessels that supply the brain with blood. The anterior circulation of the brain that controls most motor activity, sensation, thought, speech, and emotion is supplied by the carotid arteries. The posterior circulation, which supplies the brainstem and the cerebellum, controlling the automatic parts of brain function and coordination, is supplied by the vertebrobasilar arteries.

• Embolism to the brain from the heart. In some instances blood clots can form within the heart and the potential exists for them to break off and travel (embolize) to the arteries in the brain and cause a stroke.

Rupture of an artery (hemorrhage)

• Cerebral hemorrhage (bleeding within the brain substance). The most common reason to have bleeding within the brain is uncontrolled high blood pressure. Other situations include aneurysms that leak or rupture or arteriovenous malformations (AVM) in which there is an abnormal collection of blood vessels that are fragile and can bleed.

What causes a stroke?

Blockage of an artery

The blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain that is supplied by the clotted blood vessel is then deprived of blood and oxygen. As a result of the deprived blood and oxygen, the cells of that part of the brain die and the part of the body that it controls stops working. Typically, a cholesterol plaque in a small blood vessel within the brain that has gradually caused blood vessel narrowing ruptures and starts the process of forming a small blood clot.

Risk factors for narrowed blood vessels in the brain are the same as those that cause narrowing blood vessels in the heart and heart attack (myocardial infarction). These risk factors include:

• high blood pressure (hypertension),
  
• high cholesterol,
  
• diabetes, and
  
• smoking.

Embolic stroke

Another type of stroke may occur when a blood clot or a piece of atherosclerotic plaque (cholesterol and calcium deposits on the wall of the inside of the heart or artery) breaks loose, travels through the bloodstream and lodges in an artery in the brain. When blood flow stops, brain cells do not receive the oxygen and glucose they require to function and a stroke occurs. This type of stroke is referred to as an embolic stroke. For example, a blood clot might originally form in the heart chamber as a result of an irregular heart rhythm, such as occurs in atrial fibrillation. Usually, these clots remain attached to the inner lining of the heart, but occasionally they can break off, travel through the blood stream, form a plug (embolism) in a brain artery, and cause a stroke.

Cerebral hemorrhage

A cerebral hemorrhage occurs when a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue. A cerebral hemorrhage (bleeding in the brain) causes stroke symptoms by depriving blood and oxygen to parts of the brain in a variety of ways. Blood flow is lost to some cells. As well, blood is very irritating and can cause swelling of brain tissue (cerebral edema). Edema and the accumulation of blood from a cerebral hemorrhage increases pressure within the skull and causes further damage by squeezing the brain against the bony skull further decreasing blood flow to brain tissue and cells.

Subarachnoid hemorrhage

In a subarachnoid hemorrhage, blood accumulates in the space beneath the arachnoid membrane that lines the brain. The blood originates from an abnormal blood vessel that leaks or ruptures. Often this is from an aneurysm (an abnormal ballooning out of the wall of the vessel). Subarachnoid hemorrhages usually cause a sudden, severe headache, nausea, vomiting, light intolerance, and a stiff neck. If not recognized and treated, major neurological consequences, such as coma, and brain death may occur.

Vasculitis

Another rare cause of stroke is vasculitis, a condition in which the blood vessels become inflamed causing decreased blood flow to brain tissue.

Migraine headache

There appears to be a very slight increased occurrence of stroke in people with migraine headache. The mechanism for migraine or vascular headaches includes narrowing of the brain blood vessels.

What are the risk factors for stroke?

Overall, the most common risk factors for stroke are:

• high blood pressure,
  
• high cholesterol,
  
• smoking,
  
• diabetes and
  
• increasing age.

Heart rhythm disturbances like atrial fibrillation, patent foramen ovale, and heart valve disease can also be the cause.

An example of a genetic predisposition to stroke occurs in a rare condition called homocystinuria, in which there are excessive levels of the chemical homocystine in the body. Scientists are trying to determine whether the non-hereditary occurrence of high levels of homocystine at any age can predispose to stroke.

What are stroke symptoms?

When brain cells are deprived of oxygen, they cease to perform their usual tasks. The symptoms that follow a stroke depend on the area of the brain that has been affected and the amount of brain tissue damage.

Small strokes may not cause any symptoms, but can still damage brain tissue. These strokes that do not cause symptoms are referred to as silent strokes. According to The U.S. National Institute of Neurological Disorders and Stroke (NINDS), these are the five major signs of stroke:

1. Sudden numbness or weakness of the face, arm or leg, especially on one side of the body. The loss of voluntary movement and/or sensation may be complete or partial. There may an associated tingling sensation in the affected area.
   
2. Sudden confusion or trouble speaking or understanding. Sometimes weakness in the muscles of the face can cause drooling.
   
3. Sudden trouble seeing in one or both eyes
   
4. Sudden trouble walking, dizziness, loss of balance or coordination
   
5. Sudden, severe headache with no known cause
   

What should be done if you suspect you or someone else is having a stroke?

If any of the symptoms mentioned above suddenly appear, immediate emergency medical attention should be sought. The first action should be to activate the emergency medical system in your area . The goal is to get the stroke victim to a hospital as quickly as possible to confirm the diagnosis.

Angina

Introduction to angina

Chest pain is a common symptom that is caused by many different conditions. Some causes require prompt medical attention, such as angina, heart attack, or tearing of the aorta. Other causes of chest pain that may not require immediate medical intervention include spasm of the esophagus, gallbladder attack, or inflammation of the chest wall. An accurate diagnosis is important in providing proper treatment to patients with chest pain.

The diagnosis and treatment of angina is discussed below, as well as the diagnosis of other causes of chest pain that can mimic angina.

What is angina, and what are the symptoms of angina?

Angina (angina pectoris - Latin for squeezing of the chest) is chest discomfort that occurs when there is a decreased blood oxygen supply to an area of the heart muscle. In most cases, the lack of blood supply is due to a narrowing of the coronary arteries as a result of arteriosclerosis.

Angina is usually felt as:

* pressure,

* heaviness,

* tightening,

* squeezing, or

* aching across the chest, particularly behind the breastbone.

This pain often radiates to the neck, jaw, arms, back, or even the teeth.

Patients may also suffer:

* indigestion,

* heartburn,

* weakness,

* sweating,

* nausea,

* cramping, and

* shortness of breath.

Angina usually occurs during exertion, severe emotional stress, or after a heavy meal. During these periods, the heart muscle demands more blood oxygen than the narrowed coronary arteries can deliver. Angina typically lasts from 1 to 15 minutes and is relieved by rest or by placing a nitroglycerin tablet under the tongue. Nitroglycerin relaxes the blood vessels and lowers blood pressure. Both rest and nitroglycerin decrease the heart muscles demand for oxygen, thus relieving angina.

Angina is classified in one of two types: 1) stable angina or 2) unstable angina.

Stable angina

Stable angina is the most common type of angina, and what most people mean when they refer to angina. People with stable angina have angina symptoms on a regular basis and the symptoms are somewhat predictable (for example, walking up a flight of steps causes chest pain). For most patients, symptoms occur during exertion and commonly last less than five minutes. They are relieved by rest or medication, such as nitroglycerin under the tongue.

Unstable angina

Unstable angina is less common and more serious. The symptoms are more severe and less predictable than the pattern of stable angina. Moreover, the pains are more frequent, last longer, occur at rest, and are not relieved by nitroglycerin under the tongue (or the patient needs to use more nitroglycerin than usual). Unstable angina is not the same as a heart attack, but it warrants an immediate visit to your healthcare provider or hospital emergency department as further cardiac testing is urgently needed. Unstable angina is often a precursor to a heart attack.

What causes angina?

The most common cause of angina is coronary artery disease. A less common cause of angina is spasm of the coronary arteries.

Coronary artery disease

Coronary arteries supply oxygenated blood to the heart muscle. Coronary artery disease develops as cholesterol is deposited in the artery wall, causing the formation of a hard, thick substance called cholesterol plaque. The accumulation of cholesterol plaque over time causes narrowing of the coronary arteries, a process called arteriosclerosis. Arteriosclerosis can be accelerated by smoking, high blood pressure, elevated cholesterol, and diabetes. When coronary arteries become narrowed by more than 50% to 70%, they can no longer meet the increased blood oxygen demand by the heart muscle during exercise or stress. Lack of oxygen to the heart muscle causes chest pain (angina).

Coronary artery spasm

The walls of the arteries are surrounded by muscle fibers. Rapid contraction of these muscle fibers causes a sudden narrowing (spasm) of the arteries. A spasm of the coronary arteries reduces blood to the heart muscle and causes angina. Angina as a result of a coronary artery spasm is called "variant" angina or Prinzmetal angina. Prinzmetal angina typically occurs at rest, usually in the early morning hours. Spasms can occur in normal coronary arteries as well as in those narrowed by arteriosclerosis.

Coronary artery spasm can also be caused by use/abuse of cocaine. The spasm of the artery wall caused by cocaine can be so significant that it can actually cause a heart attack.

What are other causes of chest pain?

In caring for patients with chest pain, the doctor distinguishes whether the pain is related to a lack of oxygen to the heart muscle (as in angina or heart attack), or is due to another process. Many conditions are considered that can cause chest pain which is similar to that of a heart attack or angina. Examples include the following:

* Pleuritis (pleurisy): Inflammation of the lining of the lungs (pleuritis) causes sharp chest pain, which is aggravated by deep breathing and coughing. Patients often notice shortness of breath, in part due to their shallow breathing to minimize chest pain. Viral infections are the most common causes of pleurisy. Other systemic inflammatory conditions, such as systemic lupus, can also cause pleurisy.

* Pericarditis: Pericarditis is inflammation of the lining around the heart. Symptoms of pericarditis are similar to that of pleuritis.

* Pneumonia: Pneumonia (bacterial infection of the lung) causes fever and chest pain. Chest pain in bacterial pneumonia is due to an irritation or infection of the lining of the lung (pleura).

* Pulmonary embolism: blood clots travel from the veins of the pelvis or the lower extremities to the lung, the condition is called pulmonary embolism. Pulmonary embolism can cause death of lung tissue (pulmonary infarction). Pulmonary infarction can lead to irritation of the pleura, causing chest pain similar to pleurisy. Some common causes of blood clots in these veins is deep vein thrombosis (prolonged immobility, recent surgery, trauma to the legs, or pelvic infection).

* Pneumothorax: Small sacs in the lung tissue (alveoli) can spontaneously burst, causing pneumothorax. Symptoms of pneumothorax include sudden, severe, sharp chest pain and shortness of breath. One common cause of pneumothorax is severe emphysema.

* Mitral valve prolapse: Mitral valve prolapse is a common heart valve abnormality, affecting 5% to 10% of the population. MVP is especially common among women between 20 to 40 years of age. Chest pain with MVP is usually sharp but not severe. Unlike angina, chest pain with MVP rarely occurs during or after exercise, and usually will not respond to nitroglycerin.

* Aortic dissection: The aorta is the major vessel delivering blood from the left ventricle to the rest of the body. Aortic dissection (tearing of the aorta wall) is a life-threatening emergency. Aortic dissection causes severe, unrelenting chest and back pain. Young adults with aortic dissection usually have Marfan's syndrome, an inherited disease in which an abnormal form of the structural protein called collagen causes weakness of the aortic wall. Older patients develop aortic dissection typically as a result of chronic, high blood pressure, in addition to generalized hardening of the arteries (arteriosclerosis).

Rheumatic Fever (Acute Rheumatic Fever or ARF)

What is rheumatic fever?

Rheumatic fever (acute rheumatic fever or ARF) is an autoimmune disease that may occur after a group A streptococcal throat infection that causes inflammatory lesions in connective tissue, especially that of the heart, joints, blood vessels, and subcutaneous tissue. The disease has been described since the 1500s, but the association between a throat infection and rheumatic fever symptom development was not described until the 1880s. It was associated with scarlet fever (rash caused by streptococcal exotoxins) in the 1900s. Prior to the broad availability of penicillin, rheumatic fever was a leading cause of death in children and one of the leading causes of acquired heart disease in adults। The disease has many symptoms and can affect different parts of the body, including the heart, joints, skin, and brain. There is no simple diagnostic test for rheumatic fever, so the American Heart Association's modified Jones criteria (first published in 1944 and listed below) are used to assist the physician in making the proper diagnosis.

What are the Jones criteria?

Jones criteria are guidelines decided on by the American Heart Association to help doctors clinically diagnose rheumatic fever. Two major criteria or one major and two minor plus a history of a streptococcal throat infection are required to make the diagnosis of rheumatic fever.

The major criteria for diagnosis include

• arthritis in several joints (polyarthritis),



• heart inflammation (carditis),



• nodules under the skin (subcutaneous nodules or Aschoff bodies),



• rapid, jerky movements (Sydenham's chorea), and



• skin rash (erythema marginatum).

The minor criteria include

• fever,



• high ESR (erythrocyte sedimentation rate, an laboratory sign of inflammation),



• joint pain (arthralgia),



• EKG changes (electrocardiogram), and



• other laboratory findings (elevated C-reactive protein, elevated or rising streptococcal antigen test)।
  

What causes rheumatic fever?

There is a direct and well described connection between certain streptococcal infections and rheumatic fever. Most commonly, rheumatic fever is preceded by a throat infection with group A beta-hemolytic Streptococcus (strep throat, GABHS, or GAS). The bacterium causes an autoimmune (antibodies that attack the host's own cells) inflammatory response in some people which leads to the myriad of signs and symptoms described by the Jones criteria. Streptococcal throat infections are contagious, but rheumatic fever is not. The symptoms of rheumatic fever generally develop within two to three weeks of an infection with streptococcal bacteria, and usually the first symptoms are painful joints or arthritis.

What are symptoms and signs of rheumatic fever?

As mentioned above, there are quite a few symptoms associated with rheumatic fever. These include

1. carditis (inflammation of the heart), which occurs in 60% of patients is the most severe symptom of ARF and can result in permanent damage to the heart valves, and can be life threatening;

2. polyarthritis or migratory polyarthritis (joint inflammation), which usually presents first and occurs in 45% of patients and most commonly affects the large joints such as the knees;

3. Aschoff bodies (subcutaneous skin nodules), which are firm, painless lumps most frequently found around the wrists, elbows and knees. These are present in only 2% of patients;

4. erythema marginatum (rash), which occurs in 5% of patients and often described as a "serpiginous" with a wavy and snakelike appearance which has distinct erythematous (red) borders or "margins";

5. Sydenham's chorea (abnormal movements) occurs in 30% of patients and is a movement disorder comprising of purposeless volatile movements of the face and arms. This was also called St. Vitus' dance, which was named after the patron saint of the "mania dancers" of the middle ages; and