John was a 50-year-old insurance broker. He had been hospitalized three years ago with a heart attack. It had been a frightening experience for him, but he had survived and after three months had been able gradually to resume work. Initially he had lost the 15 kg. of weight as his doctor had advised. He had also given up smoking and held his work down to 30 hour a week. As time wore on, he gradually ate more, exercised less and slipped back into the cigarette habit. He was also grinding out 55 hours a week on the job. But after all, he had two children in collage and no one else was going to pay their bills.
He was more fatigued than usual and found himself stopping every few blocks to catch his breath when he was walking back to the office from lunch. I will have to start eating lunch in that restaurant around the corner. I hate the eating lunch in that restaurant around the corner. I hate the food, but he noticed that the elastic bands of his socks were leaving imprints on his lower legs, and his ankles were indented by the top edges of his shoes. As he undid his belt, he felt relief; his abdomen appeared slightly swollen and a vague discomfort in his upper abdomen was lessened without his tight pants.
His wife Janet noted how tired he looked and reminded him that he had skipped his four-month checkup with his doctor. John promised to make another appointment soon, but he was just too busy this week, to go. That night he fell asleep quickly, but about two a.m. he awoke feeling as though he needed more air. He got out of bed, went to the bathroom, and noted that lately he seemed to be getting up more at night to urinate. Last night it was three times, as a matter of fact. He went back to bed and after a while fell asleep again.
Three night later John awoke at two a.m. horrified. He was suffocating he could not get enough air. He was panting for breath and was making gurgling sound in his chest. He awakened Janet and told her to call the doctor. John went to the window and threw it open to get more air. He felt a tightness developing in his chest similar to the one he experienced when he had his original heart attack. He went to the bedside table and found the nitroglycerine that his doctor had insisted he have. After a tablet dissolved under his tongue, the chest tightness was relieved, but the shortness of breath persisted. The doctor told Janet that he would meet them at the hospital emergency room.
His diagnosis was congestive heart failure with pulmonary edema. He had warning signs of heart failure for days before the ultimate episode of pulmonary edema with fluid filling his lungs, but he had not recognized the impending danger.
Heart failure does not mean that the heart has stopped beating, and it does not mean that a person is heaving a heart attack or a myocardial infarction. It does mean that for a significant period of time the heart is not pumping enough blood. Heart failure may develop suddenly or gradually. It may occur immediately after a myocardial infarction or months or years later. The late development of heart failure is usually the result of the patients placing greater demands on his heart over a period of time than the heart is able to tolerate. In mechanical terms, the heart is able to run nicely at 30 miles an hour, but the patients keeps racing it at 60. Heart failure may also occur in other forms of heart diseases besides the type associated with atherosclerosis and myocardial infarction, if the heart is overworked.
A knowledge of some of the basic mechanisms involved in heart failure will help a person who has this problem to cope with the situation. The following is an explanation of some of the more important mechanisms.
The heart pumps a certain amount of blood per minute to the body. This amount of blood is called the cardiac output. The cardiac output for an average size man is five to six liters per minute when he is awake but not active. This can be increased in the normal person to 30 or 35 liters per minute with exercise. After a heart attack, the heart muscle is weakened and the cardiac output may fall, transiently or permanently, to two to three litters per minute at rest. If the cardiac output falls below a certain level, the body will not receive adequate blood flow and a state of heart failure will be present. This is made most dramatically evident by an abnormal collection of fluid in the body. Let us see how this fluid accumulation occurs.
Many people are surprised to learn that the human body is 65 percent fluid. Each individual body cell contains fluid, and fluid circulates around each cell. A small amount of the body fluid circulates in the blood vessels as blood. Sodium and potassium are two of the most important ingredients in body fluids. Sodium is found primarily outside of the body cells, and potassium is located within the cells. The body regulates its own fluid volume by adjusting the amount of sodium and water that is excreted by the kidneys as urine. If we drink an excess of water, the kidneys eliminate the excess to reestablish normal body content. If we eat excess salt, the kidneys get rid of the unneeded amount. If we are dehydrated, the kidneys conserve water.
About 25 percent of the blood that the heart pumps is directed to the kidneys. From this large volume of blood the kidneys are constantly filtering out waste products and producing different quantities of urine to adjust total body fluids.
If the blood flow to the kidneys is reduced, they will not function properly. Reduced blood flow could occur, for example, if the person were injured and had lost a lot of blood. The body attempts to make adjustments by the following mechanism. Kidney blood flow is monitored by special cells inside the arteries that feed the kidneys. If the flow falls below normal, these cells produce a substance which is released into the blood stream and eventually reaches the adrenal glands. The adrenal glands are triggered to produce certain hormones which are also released into the blood and eventually reach the kidneys again. Here the hormones tell the kidneys to conserve water and salt and therefore to reduce the volume of urine produced. The retained water and salt effectively increase the volume of blood contained in the blood vessel system (by expansion of the plasma, or fluid portion of the blood.) The result is an increase in the amount of blood reaching the kidneys, and these organs are again able to function.
The sensors that detect decreased kidney blood flow cannot differentiate between reduced flow caused by blood loss and reduced flow caused by poor heart function. In the latter case, the name protective mechanism operates. As a result, in the case of heart failure, an unnecessary increase in the blood volume occurs.
The excess blood inside the blood vessels is detected by the heart, which temporarily works harder to move the blood along. However, the weakened heart cannot respond beyond a certain point, and the result is a buildup of back pressure and engorgement of the blood vessels.
The fluid portion of the blood is constantly leaving the blood vessels and reentering them in the normal state of the body operation. The purpose of this movement of fluid is to bathe the body cells in needed water, chemicals, and foods. As the plasma reenters the blood vessels, it brings with it wastes from the cells which are eventually carried to the kidneys. This movement of fluid to and from the blood vessels is controlled by pressures inside the vessels and in the body tissue spaces. In heart failure, when the kidney mechanism described above results in increased blood volume and pressure, the net effect is that it is easier for fluid to leave the vessels than it is for it to return. As a consequence, excess fluid surrounds the body cells.
A person in heart failure may accumulate as little as two or three pounds of excess fluid or, if the process has persisted for a long time, as much as 20 or 30 pounds. The fluid obeys the law of gravity, and if the person in heart failure is sitting in a chair much of the time, the edema will accumulate in his feet, ankles, and legs; if lying in the bed on his back, it will tend to accumulate in the back and buttocks. The presence of edema can be detected by pressing into a soft area of tissue with a finger. If the pressure is maintained for a minute or two, and then the finger is removed, a pit or depression will persist in the tissue where pressure was applied. The accumulation of fluid can also be surmised if a patient is weight daily and if the weight is found to creep upward by a pound or two each day.
All person with edema do not have heart failure. A small amount of edema may be present in the feet or ankles of person with normal hearts who have been sitting or standing for long period of time, as is the case when traveling in a car or working as a sales person who stands up for hours at a time. Disease of the kidneys themselves and some forms of liver disease will also cause edema.
The person with heart failure and edema who has been standing or sitting much of the day may experience a strange development knows as nocturnal dyspnea when he lies down in bed at the end of the day. The fluid which has accumulated in the legs and feet is no longer held there by gravity, and the excess fluid gradually returns to the blood stream and overloads the circulation. Pressure rises in the blood vessels and starts to force excess amounts of plasma out of the small blood vessels into the tissue. The lungs, which were previously protected by gravity and their high location in the body when the person was erect, are now affected. The plasma oozes from the capillaries into the tiny air space in the lungs and blocks off the gas exchange that normally occurs there. If the person is still awake as this is happening, he may notice a gradually increasing shortness of breath and find that if he raise his head and shoulders higher by propping himself up on pillows, he is more comfortable. If asleep at this time, he may instead suddenly awaken and find himself gasping for breath. The normal reaction in this instance is to sit up or get out of bed and walk around, which again throws gravity into the situation and helps to correct the situation temporarily by drawing the excess fluid back down to the legs. Another medical term for this congestion of the lungs is pulmonary edema(pulmonary = lungs)
Pulmonary edema may occur in another circumstance in heart failure. The heart is basically a double pump. The right side of the heart receives blood from the body via the veins and pumps the blood through the lungs to receive oxygen. The left side of the heart now receives this blood from the lungs and pumps it back to the body. The left side of the heart has more work to do and is therefore equipped with large muscles which contain the majority of the blood vessels that feed the heart. In the event of a myocardial infarction, therefore, the left side is usually more severely, or exclusively, injured. The result is that one pump is now weaker than it should be. The right side of the heart will still be able to pump a normal amount of blood into the lungs, but the left side may not be able to accept the total volume and return it to the body. As a result, the blood vessels of the lungs become abnormally engorged, and the increased pressure inside the vessels can force plasma through the walls of the capillaries into the air spaces of the lungs.