heart and blood vessel disorders
Heart Failure (HF)
Causes of Heart Failure
Doctors often divide causes of heart failure into Disorders that directly affect the heart (cardiac causes) Disorders of other body systems that indirectly affect the heart (non-cardiac causes) Any disorder that directly affects the heart can lead to heart failure, as can some disorders that indirectly affect the heart. Some disorders cause heart failure quickly. Other disorders cause heart failure only after many years. Some disorders cause systolic heart failure, others cause diastolic heart failure, and some disorders, such as High Blood Pressure and some Cardiac disorders that cause heart failure may impair the entire heart or one area of the heart. In many cases, a combination of factors results in heart failure. Acommon cardiac causeof heart failure is Overview of Coronary Artery Disease (CAD) None Coronary artery disease can impair large areas of heart muscle because it reduces the flow of oxygen-rich blood to the heart muscle, which needs oxygen for normal contraction. Blockage of a coronary artery can cause a Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) , which destroys an area of heart muscle. As a result, that area can no longer contract normally. Other cardiac causesof heart failure include Myocarditis (inflammation of heart muscle) Some drugs (for example, some chemotherapy drugs) Some toxins (for example, alcohol) Heart valve disorders An abnormal connection between heart chambers (for example, Atrial and Ventricular Septal Defects ) Disorders that affect the heart's electrical conduction system and cause an abnormal heart rhythm Some genetic disorders Disorders that stiffen the heart Myocarditis (heart inflammation) caused by a bacterial, viral, or other infection can damage all or part of the heart muscle, impairing its pumping ability. Some drugs used to treat cancer and some toxins (such as alcohol) may also damage heart muscle. Overview of Heart Valve Disorders —narrowing (stenosis) of a valve, which hinders blood flow through the heart, or leakage of blood backward (regurgitation or insufficiency) through a valve—can cause heart failure. Both stenosis and regurgitation of a valve can severely stress the heart, so that over time, the heart enlarges and cannot pump adequately. An abnormal connection (for example, Atrial and Ventricular Septal Defects ) between the heart chambers can allow blood to recirculate within the heart, increasing the workload of the heart, and thus can cause heart failure. ) and cause prolonged Overview of Abnormal Heart Rhythms (especially if these are fast or irregular) can cause heart failure. When the heart beats abnormally, it cannot pump blood efficiently. Some genetic disorders can affect the heart and cause heart failure. For example, Duchenne Muscular Dystrophy and Becker Muscular Dystrophy causes weakness of the heart muscle (along with many other muscles). Heart failure may result from disorders that cause the heart’s walls to stiffen, such as infiltrations and infections. For example, in Amyloidosis , amyloid, an abnormal protein passes into (infiltrates) many tissues in the body. If amyloid infiltrates the heart’s walls, they stiffen, and heart failure results. In tropical countries, infiltration of heart muscle by certain parasites (such as in In Overview of Pericardial Disease , the sac that envelops the heart (pericardium) stiffens, preventing even a healthy heart from pumping and filling normally. Heart failure does not mean that the heart has stopped. It means the heart cannot keep up with the work required of it. Themost common non-cardiac causeof heart failure is Inadequately treated High Blood Pressure None High blood pressure stresses the heart because the heart must pump blood more forcefully than normal to eject blood into the arteries against the higher pressure. Eventually, the heart’s walls thicken (hypertrophy) and/or stiffen. The stiff heart does not fill quickly or adequately, so that with each contraction, the heart pumps less blood than it normally does. Diabetes Mellitus (DM) and As people age, the heart’s walls also tend to stiffen. The combination of high blood pressure, obesity, and Diabetes Mellitus (DM) , which are common among older people, and age-related stiffening makes heart failure particularly common among older people. Less common non-cardiac causesof heart failure include High blood pressure in arteries to the lungs (pulmonary hypertension, sometimes caused by pulmonary embolism) Anemia Thyroid gland disorders Kidney failure Some drugs Some lung disorders, such as Pulmonary Hypertension , may alter or damage blood vessels in the lungs (pulmonary arteries). As a result, the right side of the heart has to work harder to pump blood into the lungs. The person may then develop Sudden, severe blockage of a pulmonary artery by one or more blood clots ( Pulmonary Embolism (PE) ) also makes pumping blood into the pulmonary arteries difficult and can cause right-sided heart failure. Overview of Anemia is a severe deficiency of red blood cells (low blood count). Red blood cells carry oxygen from the lungs to body tissues. Anemia reduces the amount of oxygen the blood carries, so that the heart must work harder to provide the same amount of oxygen to tissues. Anemia has many causes, including heart failure itself. An overactive thyroid gland ( Hyperthyroidism ) overstimulates the heart, so that it pumps too rapidly and does not empty normally during each heartbeat. When the thyroid gland is underactive ( Overview of Kidney Failure strains the heart because the kidneys cannot remove excess fluid from the bloodstream, so the heart has a larger volume of blood to pump. Eventually, the heart cannot keep up, and heart failure develops. Some drugs, such as nonsteroidal anti-inflammatory drugs, may cause the body to retain fluid, which increases the workload of the heart and may precipitate heart failure. Aging alone does not cause heart failure. But older people are more likely to have the most common causes of heart failure, which are long-standing High Blood Pressure and Disorders can cause heart failure in two ways. They can cause problems with the heart's ability to Fill with blood Pump blood out Among older people, filling problems (called diastolic dysfunction) and pumping problems (called systolic dysfunction) are equally common. Filling problems Filling problems usually occur because the walls of the ventricles have become stiff. As a result, the ventricles cannot fill with blood normally, and too little blood is pumped out. As people age, heart muscle tends to become stiffer, making heart failure due to filling problems more likely. High blood pressure can cause filling problems because it makes the heart muscle thicker and stiffer. Filling problems are not always caused by a stiff heart. For example, in Atrial fibrillation (an abnormal heart rhythm more common with aging), the atria beat rapidly and irregularly. As a result, the atria do not move enough blood into the ventricles. If atrial fibrillation occurs suddenly in older people, heart failure may result. Pumping problems Pumping problems usually occur when the heart muscle has been damaged. A damaged heart pumps less blood, causing pressure inside the heart to increase and the heart's chambers to enlarge. The most common cause of heart damage in older people is a Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) (due to a blockage in an artery that supplies the heart with blood). Heart valve disorders can also cause pumping problems. In Aortic Stenosis (a heart valve disorder), the opening between the left ventricle and the aorta (aortic valve) narrows. As a result, pumping blood out of the heart is harder. Aortic stenosis is a common cause of heart failure in older people. If a lung disorder such as Chronic Obstructive Pulmonary Disease (COPD) (chronic obstructive pulmonary disease) or scarring (pulmonary fibrosis) has been present for a long time, blood pressure in the lungs increases. As a result, it is harder for the right ventricle to pump blood to the lungs. 