CONGENITAL HEART DEFECTS: OVERVIEW

• Congenital heart defects, or CHD, are structural heart abnormalities present before or at birth. Generally, they develop between 4 and 7 weeks of gestation, often before a woman realizes she is pregnant.

• CHD are the most common type of birth defects, affecting about 1 in 40,000 live births/year. 25% of these are considered to be critical, meaning that the baby will need at least one open heart surgery within the first year of life.

• CHD are classified according to the area of the heart affected, and how the defect affects blood flow.

• General characteristics of CHD:

• Shunting occurs when blood moves abnormally from the arterial system to the venous system, causing cyanosis.

• Cyanosis is a bluish tint to the skin and mucous membranes caused by a lack of sufficient oxygen.

• Alterations in pulmonary blood flow can cause problems in infants, including failure-to-thrive, fatigue, and dyspnea (trouble breathing).

• Many CHD can be diagnosed prenatally through the use of sonogram, or they may be diagnosed shortly after birth.

• Around 30% of the time, CHD are accompanied by other genetic abnormalities.

CONGENITAL HEART DEFECTS

• Ventricular septal defects (VSD) and atrial septal defects (ASD) are the most common type of CHD.

• These defects may be so small that they are asymptomatic, or do not cause symptoms and need no treatment.

If the defects are large enough to cause shunting, they must be surgically repaired

• Pulmonary stenosis accounts for roughly 10% of all CHD.

• Stenosis means “narrowing.” Pulmonary stenosis causes narrowing of the pulmonary artery, which obstructs blood flow from the right ventricle to the pulmonary artery.

• Pulmonary stenosis can be treated with stents, which may be inserted via a cardiac catheterization, or an angioplasty via an open heart surgery.

CONGENITAL HEART DEFECTS: TETRALOGY OF FALLOT

• Tetralogy of Fallot is a critical CHD, and is about 5-7% of all CHD.

• Tetralogy of Fallot is actually 4 heart defects: a VSD, the aorta shifts to the right, pulmonary stenosis, and hypertrophy of the right ventricle, due to the increased work needed to overcome the pulmonary stenosis.

• Hypertrophy is a term that means abnormally enlarged; hyper- means “excessive,” troph/o means “development,” and –y is a noun ending.

• Multiple open heart surgeries are required for all babies with Tetralogy of Fallot.

CONGENITAL HEART DEFECTS: TRANSPOSITION OF THE GREAT ARTERIES

• Transposition of the Great Arteries (TGA) is a condition in which the aorta and the pulmonary artery are essentially switched.

• The aorta rises from the right ventricle instead of the left, and the pulmonary artery rises from the left ventricle instead of the right.

• This causes the deoxygenated blood to circulate the systemic circuit, and the oxygenated blood to circulate the pulmonary circuit, causing lack of oxygenation to the rest of the body.

• Open heart surgery is required for all babies with this condition within 2-3 weeks of age.

HEART FAILURE AND ANGINA

• Heart failure, which is also called congestive heart failure, is most common in the elderly.

• Heart failure occurs when the heart cannot pump out all of the blood that it receives, which causes congestion due to the backup of that blood.

• Left-sided failure occurs when fluid begins to build up in the lungs, because the left side of the heart cannot pump all of the oxygenrich blood through the aorta to systemic circulation.

• Right-sided failure occurs when the right side of the heart is weak, causing an increase in fluid in the systemic circulation.

• This will cause edema, or swelling. Edema is usually seen first in the legs and feet due to the effects of gravity.

• Cardiomegaly is the enlargement of the heart as a compensation strategy for its decreased output.

• Cardiomegaly is often seen in patients with congestive heart failure, because the heart enlarges due to the increased work load.

• Angina, also known as angina pectoris, is severe chest pain due to lack of blood flow from the myocardium, or heart muscle.

• Generally, angina will get progressively worse until a heart attack occurs.

• There are two types of angina:

• Stable angina occurs only with exercise

• Unstable angina is more serious, and occurs with exercise or rest.

ATHEROSCLEROSIS AND CORONARY ARTERY DISEASE

• Coronary artery disease, or CAD, is caused by atherosclerosis, which is the hardening of the coronary arteries that supply blood to the myocardium.

• CAD leads to angina, and eventually to a heart attack, if left unmanaged.

• Atherosclerosis is the hardening of arteries as well as narrowing caused by the buildup of plaque (also called cholesterol), on the arterial walls. Ather/o means “plaque,” and –sclerosis means “the abnormal narrowing.”

• Plaque is a fatty deposit on the artery. Do not confuse the plaques of atherosclerosis to dental plaque, which is a different substance.

• A lumen is the opening in an artery though which blood flows. Plaque can protrude into the lumen, decreasing blood flow.

• An atheroma, which can be seen in atherosclerosis, is a plaque deposit on or in the arterial wall. Ather/o means “plaque,” and –oma means “tumor.”

MYOCARDIAL INFARCTION AND MYOCARDIAL DISEASE

• A myocardial infarction (MI), more commonly known as a heart attack, occurs when there is a complete blockage of one or more coronary arteries, usually due to plaque. My/o means “muscle,” cardi/o means “heart,” and an infarction is a lack of blood.

• This blockage is called an occlusion, which means “total blockage.”

• An infarction is a sudden lack of blood. The infarct is the localized, specific area of tissue death that is caused by the lack of sufficient blood flow.

• Signs and symptoms of a heart attack are pain and pressure in the chest that spreads to the back, jaw, and arm. Women may also have weakness and fatigue, and/or stomach pain.

• Diseases of the myocardium are called cardiomyopathies, and are diseases of the heart muscle itself. Cardi/o means “heart,” my/o means “muscle,” and –pathy means “disease.”  Dilated cardiomyopathy causes muscles of the heart to enlarge and work less effectively.

ARRHYTHMIA

• Arrhythmia is the loss of a normal, rhythmic heart beat.

• Arrhythmias can be minor and transient, or temporary, or they can be fatal. The severity depends on the type of rhythm.

• Most often, arrhythmias are caused by a problem with the conduction system of the heart.

• The following are some terms related to arrhythmias:

• Bradycardia is an abnormally slow resting heart rate, below 60 beats per minute (bpm). Brady- means “slow.”

• Tachycardia is an abnormally fast resting heart rate, above 100 bpm. Tachy- means “fast.”

• A palpitation is a pounding or racing heart beat, which can occur with or without an accompanying arrhythmia.

• Cardiac arrest is the cessation of a heart beat, or an arrhythmia that prevents adequate perfusion of tissues.

• Asystole is also called a flat line, and is the lack of electrical activity in the heart. In asystole, there is no heart beat, and therefore no blood flow. A- means “without,” and –systole means “heartbeat.”

• Sudden cardiac death occurs when treatment is not successful within a few minutes of the onset of cardiac arrest.

HEART RHYTHM DISORDERS

• Fibrillation is a rapid, uncontrolled heartbeat.

• Atrial fibrillation, or A-Fib, occurs when the atria contract, but do so in an irregular and twitching manner. This causes an irregular, twitching heart beat, which is usually between 80 and 100 bpm.

• Paroxysmal supraventricular tachycardia are very rapid heart beats that begin in the atria. Paroxysmal is a term that means “sudden,” so this disorder begins and ends rather suddenly.

• Ventricular fibrillation, or V-Fib, is caused by rapid, irregular, and ineffective ventricular contractions, causing the muscle to quiver rather than beat. V-Fib is often the cause of cardiac arrest.

• Ventricular tachycardia, or V-Tach, is a rapid heart beat that begins in the ventricles. This condition can be fatal, because the heart beat is too rapid to be effective at perfusing the body’s tissues. Tachy- means “rapid,” cardi/o means “heart,” and –ia means “pertaining to.”

HEART VALVE DISORDERS

• A heart murmur is the most common valve disorder, and is an abnormal blowing or clicking heard when listening to heart sounds. A murmur is generally caused by a valve issue.

• Valvulitis is the inflammation of a valve. Valvul/o means “valve,” and –itis means “inflammation.”

• Valvular prolapse is the abnormal protrusion of a valve that prevents it from closing completely.

• Prolapse is the falling or drooping of an organ or internal structure.

• Valvular prolapses are named for the valve that they affect. For example, a common type of prolapse is mitral valve prolapse.

• Valvular stenosis is the narrowing, stiffening, thickening, or blockage of heart valve(s).

• Recall that stenosis means “the abnormal narrowing of an opening.”

INFECTIONS OF THE HEART

• Carditis is a general term that means “inflammation of the heart.” Card/o means “heart,” and –itis means “inflammation.”

• Endocarditis s the inflammation of the inner heart’s lining. End/o means “inside,” card/o means “heart,” and –itis means “inflammation.”

• Bacterial endocarditis is caused by a bacterial infection of the blood stream, which causes the inflammation in the heart. This disorder can occur due to dental surgery in particular.

• Pericarditis is an inflammation of the pericardium, which causes fluid buildup. This fluid restricts the pumping action of the heart. Peri- means “around,” card/o means “heart,” and –itis means “inflammation.”

• Myocarditis is inflammation of the heart muscle due to a viral infection, most commonly an enterovirus. My/o means “muscle,” cardi/o means “heart,” and –itis means “inflammation.”

BLOOD VESSEL ABNORMALITIES AND DISORDERS

• The following are some general terms regarding blood vessel abnormalities:

• Angiostenosis is the abnormal narrowing of a blood vessel. Angi/o means “vessel,” and –stenosis means “abnormal narrowing.”

• Hemangiomas are benign tumors that are composed of newly formed vessels. They are a type of birthmark. Hem/o means “blood,” angi/o means “vessels,” and –oma means “tumor.”

• Hypoperfusion is the deficient blood flow to an organ or body structure. V

• Vasculitis is the inflammation of a vessel. There are several categories of vasculitis:

• Angiitis or arteritis is the inflammation of an artery. Angi/o means “artery,” and –itis means “inflammation.”

• Polyarteritis occurs when immune cells attack arteries. This often includes several small and medium arteries simultaneously. Poly- means “many,” arteri/o means “artery,” and –itis means “inflammation.”

• Temporal arteritis is a condition in which the cells of the temporal artery enlarge. This type of vasculitis causes headaches, jaw pain, blindness, and can lead to a stroke in rare cases.

BLOOD VESSEL DISORDERS: ARTERIES AND VEINS

• There are several disorders that are specific to arteries:

• An aneurysm is a weakened spot or the enlargement of an artery, which makes it susceptible to rupture. A rupture can lead to death due to excessive blood loss.

• Arteriosclerosis is the hardening of arteries. Arteri/o means “artery,” and –sclerosis means “the abnormal hardening.”

• Arteriostenosis is the narrowing of arteries. Arteri/o means “artery,” and –stenosis means “the abnormal narrowing.”

• There are also several disorders specific to the veins.

• Chronic venous insufficiency is decreased blood flow due to leaky valves and blocked arteries. Due to gravity, this condition usually affects the feet and legs first.

• Phlebitis is venous inflammation which occurs when the walls of a vein are compromised and a clot forms. Some cases of phlebitis are caused by poor phlebotomy technique. Phleb/o means “vein,” and –itis means “inflammation.”

• Varicose veins, or swollen veins, are usually found in superficial leg veins. They occur due to blood pooling in the veins, and are more common with age.

CLOTS: THROMBOSES AND EMBOLI

• A thrombus is a blood clot attached to the wall of an artery or vein. Thrombosis is the condition of having a thrombus.

• Thrombotic occlusion is the blockage of an artery by a thrombus.

• Coronary thrombosis is heart muscle damage that is caused by a coronary artery thrombus.

• Deep vein thrombosis is a thrombus attached to the wall of a deep vein. This can happen frequently in leg veins, which can break away and move to the lung, which is fatal.

• An embolus is a foreign object, such as a clot, air, gas, tissue, or tumor that circulates the blood.

• Embolism is the sudden blockage of a vessel by an embolus. This can also be fatal.

• Peripheral vascular disease are vessel disorders not found in the heart and brain, so in the periphery of the body.

• Peripheral arterial occlusive disease, or PAOD, is a common disorder caused by atherosclerosis. This can impair circulation to the vital organs and extremities.

• Raynaud’s disease are attacks of PAOD triggered by cold or stress. This causes paleness, cyanosis, and redness of the fingers and toes due to decreased circulation.

BLOOD PRESSURE DISORDERS

• Hypertension, or high blood pressure, is the elevation of arterial blood pressure. This will eventually damage the vascular and cardiac systems. Hyper- means “excessive.”

• The following are the parameters for a diagnosis of hypertension:

• Stage 1: Systolic between 140 and 150 mm/Hg, and a diastolic between 90 and 99 mm/Hg.

• Stage 2: Systolic above 160 mm/Hg, and a diastolic greater than 100 mm/Hg.

• Primary hypertension is also called essential or idiopathic hypertension, and has no known cause.

• Secondary hypertension is caused by another medical problem. It usually resolves when the original problem is fixed. Common conditions leading to secondary hypertension are kidney disease or an adrenal tumor.

• Malignant hypertension is an extremely high blood pressure. This increased blood flow damages vessels in the brain, organs, optic nerves, and can cause kidney and heart disease.

• Hypotension is an abnormally low arterial blood pressure. Hypo- means “low.”

• Hypotension leads to dizziness, light-headedness, and fainting.

• Orthostatic hypotension is also called postural hypotension, and occurs when the blood pressure drops when a person stands. Orth/o means “straight” and –static means “constant.”

• Orthostatic means “standing in an upright position.”

BLOOD DISORDERS

• In general, any pathology (or disease) of the cells in the blood is called blood dyscrasia.

• There are many disorders of the blood. They include decreased numbers of cells, as well as increased numbers of cells.

• The following are some disorders involving decreased numbers of cells.

• Leukopenia is a decrease in the overall white blood cell count, which are the cells that fight off infections in the body. Leuk/o means “white blood cells,” and –penia means “deficiency.”

• Leukopenia increases the risk of infection, as well as makes it harder to recover from an illness.

• Thrombocytopenia is a decrease in the number of platelets circulating in the blood. This can cause abnormal bleeding, since these fragments aid in blood clotting. Thromb/o means “clot,” cyt/o means “cell,” and –penia means “deficiency.”

• Anemia is a decrease in the number of red blood cells. The severity of anemia is measured by the oxygencarrying capacity of the cells, which is also called the hemoglobin. A decreased hemoglobin means that there is decreased oxygen delivery to the tissues, which in turn leads to decreased energy levels for the patient.

TYPES OF ANEMIA

• Iron-deficiency anemia is the most common type of anemia. Iron is critical to hemoglobin function, so without enough iron, the blood cells cannot carry enough oxygen.

• Hemolytic anemia is a decrease in the number of circulating red blood cells due to red blood cell destruction by the spleen. Hemolysis is the destruction of red blood cells, so hemolytic indicates a condition in which the red blood cells are being destroyed. Hem/o means “blood,” and –lysis means “destruction.”

• Megaloblastic anemia is caused by a folic acid or B12 deficiency. In this condition, the red blood cells are larger than normal. Megal/o means “large,” and blast/o means “formation,” and –ic means “pertaining to.”

• Pernicious anemia is due to the lack of a protein called intrinsic factor that allows the body to absorb B12 from the gastrointestinal tract. Without intrinsic factor, red blood cell production is diminished.

• Sickle-cell anemia is an inherited disorder. Although not a deficiency in useful hemoglobin, the hemoglobin present is abnormal, and causes red blood cells to form in a sickle shape, which can impair blood flow, damaging organs and body systems.

• Thalassemia is another inherited disorder that causes mild to severe anemia. Thalassemia is a spectrum disorder, meaning that it can range from severe to mild. It leads to a decreased red blood cell count and hemoglobin count.

• Aplastic anemia is the absence of all blood cell lines from the bone marrow: white blood cells, red blood cells, and platelets. Aplastic anemia is very serious, and requires a stem cell transplant for treatment. A- means “without,’ plast/o means “formation,” and –ic means “pertaining to.”

DISORDERS WITH INCREASED CELLS

• Polycythemia is an increase in the number of red blood cells due to increased red cell production in the bone marrow. Poly- means “many,” cyt/o means “cells,” and –emia means “blood.”

• Thrombocytosis is an abnormal increase in the number of platelets, which can cause too much blood clotting. Thromb/o means clot, cyt/o means “cell,” and –osis means “abnormal condition.”

• Hemochromatosis is the increased absorption of iron in the gastrointestinal tract. This can lead to accumulations in the vital organs, causing damage to them. Hem/o means “blood,” chromat/o means “color,” and –osis means “abnormal condition.”

• Septicemia is a bacterial infection of the blood, also called bacteremia. It is characterized by sudden signs and symptoms, including a high fever, chills, tachycardia, and increased respiratory rate. Sept/o means “infection,” and –emia means “blood.”

• Septicemia can lead to sepsis, which is a life-threatening condition.

• Leukemia is a cancer of the blood with increased white blood cell production, which can be found in the peripheral blood, bone marrow, organs, and body fluids. Leuk/o means “white blood cell,” and –emia means “blood condition.”

• The white blood cells found in a leukemic patient are abnormal, and do not function properly. This causes weakness and an increased susceptibility to infection.

• Myelodysplastic syndrome, or MDS, is the insufficient production of a cell line due to dysfunctional bone marrow. This can be a precursor to leukemia. Myel/o means “bone marrow,” dys- means “bad,” plast/o means “formation,” and –ic means “pertaining to.”

GENERAL BLOOD DISORDERS

• A hemorrhage is a large amount of blood loss in a short period of time. If severe enough, this condition can be fatal. Hem/o means “blood,” and –rrhage means “bleeding or discharge.”

• A transfusion reaction occurs when the blood of a recipient and donor do not match. This can cause a lifethreatening immune response if certain blood groups are involved.

• Cholesterol is a fatty substance found in the blood, which is essential to the human body. Cholesterol helps the body produce cell membranes, hormones, and vitamin D.

• Cholesterol comes primarily from the diet, but it can also be produced by the liver.

• Hyperlipidemia is an increase in the levels of cholesterol and other fatty acids in the blood, which could eventually lead to heart disease. Hyper- means “excessive,” lipid/o means “fat,” and –emia means “blood condition.”

• Research is ongoing as to the extent to which cholesterol and fatty acids affect heart health.