Cardiology

Acute Coronary Syndrome
This is an umbrella term used to cover any group of clinical symptoms compatible with acute myocardial ischemia.  Acute myocardial ischemia is chest pain due to insufficient blood supply to the heart muscle that results from coronary artery disease (also called coronary heart disease).
Patients who have symptoms of acute myocardial ischemia and are given an electrocardiogram (ECG or EKG) may or may not have an ST elevation.  (An ECG provides a graph of the heartbeat.  Portions of the graph are labeled P, Q, R, S and T.  An ST elevation describes a rise in a particular portion of this graph.) 

Most patients who have ST-segment elevation will ultimately develop a Q-wave acute myocardial infarction (heart attack).  (The Q-wave describes another part of an ECG graph.)  Patients who have ischemic discomfort without an ST-segment elevation are having either unstable angina, or a non-ST-segment elevation myocardial infarction that usually leads to a non-Q-wave myocardial infarction.
Acute coronary syndrome thus covers the spectrum of clinical conditions ranging from unstable angina to non-Q-wave myocardial infarction and Q-wave myocardial infarction.  These life-threatening disorders are a major cause of emergency medical care and hospitalization .  Coronary heart disease is the leading cause of death in the United States.  Unstable angina and non-ST-segment elevation myocardial infarction are very common manifestations of this disease

Acute myocardial infarction: (  heart attack)
The term "myocardial infarction" focuses on the heart muscle, which is called the myocardium ,and the changes that occur in it due to the sudden deprivation of circulating blood. This is usually caused by  arteriosclerosis with narrowing of the coronary arteries, the culminating event being a  thrombosis (clot). The main change is death (necrosis) of myocardial tissue.
The word "infarction" comes from the Latin "infarcire" meaning "to plug up or cram." It refers to the clogging of the artery, which is frequently initiated by cholesterol piling up on the inner wall of the blood vessels that distribute blood to the heart muscle.

Angina Pectoris
Angina pectoris is the medical term for chest pain or discomfort due to coronary heart disease.  Angina is a symptom of a condition called myocardial ischemia.  It occurs when the heart muscle (myocardium) doesn't get as much blood (hence as much oxygen) as it needs. This usually happens because one or more of the heart's arteries (coronary blood vessels that supply blood to the heart muscle) is narrowed or blocked.  Insufficient blood supply is called ischemia.

Angina also can occur in people with valvular heart disease, hypertrophic cardiomyopathy (this is an enlarged heart due to disease) or uncontrolled high blood pressure.  These cases are rare, though.
Typical angina is uncomfortable pressure, fullness, squeezing or pain in the center of the chest.  The discomfort also may be felt in the neck, jaw, shoulder, back or arm.  Many types of chest discomfort aren't related to angina.  Acid reflux (heartburn) and lung infection or inflammation are examples.

Atherosclerosis
Atherosclerosis is a slow, complex disease that typically starts in childhood and often progresses when people grow older. In some people it progresses rapidly, even in their third decade. Many scientists think it begins with damage to the innermost layer of the artery. This layer is called the endothelium (en"do-THE'le-um). Causes of damage to the arterial wall include:

Tobacco smoke greatly worsens atherosclerosis and speeds its growth in the coronary arteries, the aorta and arteries in the legs. (The coronary arteries bring blood to the heart muscle; the aorta is the large vessel that the heart pumps blood through to the body.)
Because of the damage to the endothelium, fats, cholesterol, platelets, cellular waste products, calcium and other substances are deposited in the artery wall. These may stimulate artery wall cells to produce other substances that result in further buildup of cells.
These cells and surrounding material thicken the endothelium significantly. The artery's diameter shrinks and blood flow decreases, reducing the oxygen supply. Often a blood clot forms near this plaque and blocks the artery, stopping the blood flow.

Hypertension
High blood pressure (HBP) or hypertension means high pressure (tension) in the arteries. Arteries are vessels that carry blood from the pumping heart to all the tissues and organs of the body. High blood pressure does not mean excessive emotional tension, although emotional tension and stress can temporarily increase blood pressure. Normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called "pre-hypertension", and a blood pressure of 140/90 or above is considered high.

An elevation of the systolic and/or diastolic blood pressure increases the risk of developing heart (cardiac) disease,
kidney (renal) disease, hardening of the arteries (atherosclerosis or arteriosclerosis), eye damage, and stroke (brain damage). These complications of hypertension are often referred to as end-organ damage because damage to these organs is the end result of chronic (long duration) high blood pressure. For that reason, the diagnosis of high blood pressure is important so efforts can be made to normalize blood pressure and prevent complications.

Hypertension is clearly a major public health problem.

Arrhythmias
Types of Arrhythmias
Arrhythmias stem from several causes. The heart’s natural timekeeper—a small mass of special cells called the sinus node—can malfunction and develop an abnormal electrical impulse rate. Or, because all heart tissue is capable of starting a beat, any part of the heart muscle also can interrupt the electrical rhythm or even take over as the heart’s pacemaker, setting off an abnormal heartbeat. When one of these events interrupts the heart’s normal beat, arrhythmias can occur. Doctors frequently see these five types of arrhythmias—