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Cardiovascular System

Critical Care

The Cardiovascular System is the heart and all of the vessels that carry blood to the body. Blood carries oxygen and food that every cell in the body needs for life. If the heart or blood vessels fail to get enough blood to the body, the important organs of the body may be temporarily or permanently damaged.

Myocardial infarction - or "heart attack" - happens when the heart muscle itself doesn't get enough blood because one or more of its blood vessels, called coronary arteries, becomes blocked (this used to be called "hardening of the arteries"). When this happens, an awake person may have chest pain or pressure, pain in the jaw, neck or shoulder, shortness of breath, sweating, nausea or vomiting. Critically ill patients are often not awake and so they may not be able to complain of these symptoms. Heart attacks are treated by measures to get blood flowing back through the blocked coronary arteries, but the longer the blockage is there, the more likely that heart cells will die leading to permanent damage.

Treatments include medicines that thin the blood (like aspirin or heparin) or break down the clots (like a medicine called "TPA"), reduce the work of the heart (like nitroglycerin and medicines called "beta-blockers" or "ACE-inhibitors"). Often medicines are not enough and doctors must do a procedure called an "angiogram" in which a catheter is placed into the leg or arm and pushed up into the heart, and dye is given to show where the blockage is. Doctors may then be able to open the blockage with a balloon (called "angioplasty") or with a tiny hollow pipe (called a "stent"). However, in some cases, the blockage cannot be opened up at the time of an angiogram. Surgery may be needed in which blood vessels are removed from one part of the body (often the leg) and used to carry blood to skip over, or "bypass," the blockage. This is called "bypass surgery" or "CABG" (pronounced "cabbage" short for coronary artery bypass graft).

Shock - is a term used to describe when the blood pressure drops to a dangerously low level. If the pressure falls enough, the cells in the body don't get enough oxygen and begin to die. If enough cells die, organs of the body, like the kidneys, brain and liver, may also stop working right. Common reasons for shock are severe infections (this is called "septic shock"), heart attacks (this is called "cardiogenic shock") or severe blood loss (called "hemorrhagic shock"). There are also other less common causes. In each situation, treatment of shock involves fixing the cause. In the case of septic shock, the infection must be found and treated with antibiotics. In the case of shock due to heart problems, the heart attack must be treated (see discussion of "Myocardial Infarction").

Sometimes shock cannot be treated and in other cases, if it has gone on for some time, the organs of the body have been damaged too much for the patient to survive.

Arrhythmia - is a term used to describe when the heartbeat, which normally goes at a regular rate of 60 to 100 beats every minute, becomes too fast or too slow. Sometimes medicines can be given to help. But other times, abnormal heartbeats are so bad that not enough blood gets to the organs of the body or blood backs up into the lungs. If this happens an electrical shock, given by two paddles on the chest wall, may be needed to put the heart back to a more normal rate. However, shocks are not successful in all cases and in some cases, the heart can even stop after a shock, in which case cardiopulmonary resuscitation (CPR) may be needed (see Information Sheet on Cardiopulmonary Resuscitation).

Congestive Heart Failure - is a term used to describe when the heart fails to pump enough blood forward to the body and as a result, fluid builds up in the lungs, called "pulmonary edema." This can cause shortness of breath, sometimes so bad that a patient may need to go on a breathing machine until it can be treated (see Information Sheet on Mechanical Ventilators). Congestive heart failure can usually be treated with medicines like nitroglycerin and diuretics, which help the kidneys to get rid of excess fluids. But sometimes, other, stronger medicines are needed and in some cases the heart works so poorly that nothing short of getting a heart transplant can help the patient to feel better.