Hemophilia

Hemophilia is not one disease but rather one of a group of inherited bleeding disorders that cause abnormal or exaggerated bleeding and poor blood clotting. The term is most commonly used to refer to two specific conditions known as hemophilia A and hemophilia B, which will be the main subjects of this article. Hemophilia A and B are distinguished by the specific gene that is mutated (altered to become defective) and codes for a defective clotting factor (protein) in each disease. Rarely, hemophilia C is encountered, but its effect on clotting is far less pronounced than A or B.
Hemophilia A and B are inherited in an X-linked recessive genetic pattern and are therefore much more common in males. This pattern of inheritance means that a given gene on the X chromosome expresses itself only when there is no normal gene present. For example, a boy has only one X chromosome, so a boy with hemophilia has the defective gene on his sole X chromosome (and so is said to be hemizygous for hemophilia). Hemophilia is the most common X-linked genetic disease.
Although it is much rarer, a girl can have hemophilia, but she would have to have the defective gene on both of her X chromosomes or have one hemophilia gene plus a lost or defective copy of the second X chromosome that should be carrying the normal genes. If a girl has one copy of the defective gene on one of her X chromosomes and a normal second X chromosome, she does not have hemophilia but is said to be heterozygous for hemophilia (a carrier). Her male children have a 50% chance of inheriting the one mutated X gene and thus has a 50% chance of inheriting hemophilia from their carrier mother.
Hemophilia A occurs in about 1 out of every 5000 live male births. Hemoplilia A and B occurs in all racial groups. Hemophilia A is about four times more common than B; B occurs in about 1 out of 20- 34,000 live male births.
Hemophilia has been called the Royal Disease because Queen Victoria, Queen of England from 1837 to 1901, was a carrier. Her daughters passed the mutated gene on to members of the royal families of Germany, Spain, and Russia. Alexandra, Queen Victoria's granddaughter, who became Tsarina of Russia in the early 20th century when she married Tsar Nicholas II, was a carrier. Their son, the Tsarevich Alexei, suffered from hemophilia.

Hemophilia At A Glance

• Hemophilia is one of a group of inherited bleeding disorders that cause abnormal or exaggerated bleeding and poor blood clotting.
  
• Hemophilia A and B are inherited in an X-linked recessive genetic pattern, so males are commonly affected while females are usually carriers of the disease.
  
• Hemophilia A is caused by a deficiency of clotting Factor VIII, while hemophilia B (also called Christmas disease) results from a deficiency of Factor IX.
  
• Hemophilia varies in its severity among affected individuals.
  
• Symptoms include excessive bleeding from any site in the body; long-term damage to joints from repeated bleeding episodes is characteristic.
  
• Treatment involves coagulation factor replacement therapy.
  
• The formation of inhibitors to the treatment factor concentrates is a significant complication of treatment.
  
• Gene therapy treatments are a source of active research and hold promise for the future.

hemophilia Infections

Blood-borne infections, such as the HIV virus and hepatitis B and C, were a major complication of treatment for hemophilia during the 1980s. These infections were transmitted through the factor concentrates and other blood products that were used to treat hemophilia. The use of large blood donor pools to prepare factor concentrates and the lack of specific tests for infectious agents both contributed to the contamination of blood products used to treat hemophilia. By 1985, about 90% of people with severe hemophilia were infected with the HIV virus, and about half of all people with hemophilia were HIV-positive. Today, improved screening and manufacturing practices including virus removing techniques as well as the development of recombinant factors have essentially eliminated this tragic complication of treatment.

Can hemophilia be prevented?

Hemophilia is a genetic (inherited) disease and cannot be prevented. Genetic counseling, identification of carriers through molecular genetic testing, and prenatal diagnosis are available to help individuals understand their risk of having a child with hemophilia.

What is the outlook (prognosis) for hemophilia?

Before factor concentrates were developed, those with hemophilia had a significantly decreased life expectancy. Life expectancy before the 1960s for those with severe hemophilia was limited to 11 years. Currently, the mortality (death) rate for males with hemophilia is twice that of healthy males. As mentioned before, the increase in HIV and hepatitis infections associated with therapy during the 1980s led to a corresponding increase in death rates.
Currently, prompt and adequate treatment can greatly reduce the risks of life-threatening bleeding episodes and the severity of long-term damage to joints, but joint deterioration remains a chronic complication of hemophilia.

treatments for hemophilia

The mainstay of treatment is replacement of the blood clotting factors. Clotting factor concentrates can be purified from human donor blood or made in the laboratory using methods that do not use donor blood. This type of therapy is known as replacement therapy. Clotting factor replacement therapy is carried out by infusing the clotting factor concentrates into a vein, much like a blood transfusion. This type of therapy can be administered at home with proper instruction and training.
Depending upon the severity of the condition, replacement therapy may be carried out on an as-needed basis (called demand therapy) or on a regular basis to prevent bleeding episodes (known as prophylactic therapy).
People who have mild cases of hemophilia A are sometimes treated with the drug desmopressin, also known as DDAVP. This drug stimulates release of more clotting factor by the body. It is administered either slowly through the intravenous route (IV) or occasionally, in nasal spray form.
Pain relievers may be prescribed for symptom relief, but pain relievers other than aspirin or non-steroidal anti-inflammatory medications (such as naproxen, ibuprofen) must be used, since these types of drugs further inhibit the blood's ability to clot. Acetaminophen (Tylenol and others) is often given for pain relief.

What are complications of treatment?

Inhibitors

A major complication of treatment is the development of so-called inhibitors to the clotting factors. Inhibitors (antibodies) are produced because the body sees the factor concentrates used to treat patients to reduce or prevent bleeding, as foreign and activates an immune response in the patient to destroy the foreign substances (factor VIII or factor IX).
Inhibitors to factor VIII are the most common and occur in about one-third of those with severe hemophilia A and about 1 out of every 50 people with mild or moderate hemophilia A. They typically develop in childhood in those with severe hemophilia A and later in life in milder cases. Inhibitors destroy both the replacement factor VIII concentrates as well as any factor VIII that is present in the body. This is a serious complication of treatment because the factor concentrates are no longer effective in treating the condition. The action of inhibitors to destroy factor VIII concentrates shows different degrees of severity among individuals and can even vary over time in the same individual.
In about two-thirds of cases, the inhibitors disappear on their own or with treatment known as immune tolerance therapy (ITT) or immune tolerance induction (ITI). In cases of severe hemophilia A with persistence of inhibitors, other factor concentrates, such as activated prothrombin complex concentrate or recombinant factor VIIa, are administered to attempt to help control bleeding.
The development of inhibitors to factor IX is much less common and occurs in about 1% of those with hemophilia B. However, these can cause a very serious allergic reaction when factor IX concentrates are given. Immune tolerance therapy to eliminate inhibitors is less successful than with hemophilia A.

hemophilia diagnosed

The majority of patients with hemophilia have a known family history of the condition. However, about one-third of cases occur in the absence of a known family history. Most of these cases without a family history arise due to a spontaneous mutation in the affected gene. Other cases may be due to the affected gene being passed through a long line of female carriers.
If there is no known family history of hemophilia, a series of blood tests can identify which part or protein factor of the blood clotting mechanism is defective if an individual has abnormal bleeding episodes.
The platelet (a blood particle essential for the clotting process) count should be measured as well as two indices of blood clotting, the prothrombin time (PT) and activated partial thromboplastin time (aPTT). A normal platelet count, normal PT, and a prolonged aPTT are characteristic of hemophilia A and hemophilia B. Specific tests for the blood clotting factors can then be performed to measure factor VII or factor IX levels and confirm the diagnosis.
Genetic testing to identify and characterize the specific mutations responsible for hemophilia is also available in specialized laboratories.

Is it possible to know if you are a carrier of hemophilia?

Since men with the genetic mutation will have hemophilia, a man who does not have the condition cannot be a carrier of the disease. A woman who has a son with known hemophilia is termed an obligate carrier, and no testing is needed to establish that she is a carrier of hemophilia.
Women whose carrier status is unknown can be evaluated either by testing for the clotting factors or by methods to characterize the mutation in the DNA. The DNA screening methods are generally the most reliable.
Prenatal diagnosis is also possible with DNA-based tests performed on a sample obtained through amniocentesis or chorionic villus sampling. Most individuals are seen and tested by consultants who specialize in genetically linked diseases.

signs and symptoms of hemophilia

Hemophilia can vary in its severity, depending upon the particular type of mutation (genetic defect). The degree of symptoms depends upon the levels of the affected clotting factor. Severe disease is defined as <1% factor activity, 1% to 5% factor activity is moderate disease, and greater than 5% factor activity constitutes mild disease. The extent of bleeding is dependent upon the severity (the amount of factor activity) and is similar for hemophilia A and B.
With severe hemophilia (A or B), bleeding begins at an early age and may occur spontaneously. Those with mild hemophilia may only bleed excessively in response to injury or trauma. Female carriers of hemophilia have variable degrees of factor activity; some may have near normal levels and do not show any bleeding tendencies, while some may have less than the predicted 50% reduction and may bleed more often than non-carrier females.
In severe hemophilia, bleeding episodes usually begin within the first 2 years of life. Heavy bleeding after circumcision in males is sometimes the first sign of the condition. Symptoms may develop later in those with moderate or mild disease. The bleeding of hemophilia can occur anywhere in the body. Common sites for bleeding are the joints, muscles, and gastrointestinal tract. Specific sites and types of bleeding are discussed below.

• Hemarthrosis (bleeding into the joints) is characteristic of hemophilia. The knees and ankles are most often affected. The bleeding causes distension of the joint spaces, significant pain, and over time, can be disfiguring. Over time, joint destruction occurs, and joint replacement surgeries can be required.
  
• Bleeding into the muscles may occur with hematoma formation (compartment syndrome).
  
• Bleeding from the mouth or nosebleeds may occur. Bleeding after dental procedures is common, and oozing of blood from the gums may occur in young children when new teeth are erupting.
  
• Bleeding from the gastrointestinal tract can lead to blood in the stool.
  
• Bleeding from the urinary tract can lead to blood in the urine (hematuria).
  
• Intracranial hemorrhage (bleeding into the brain or skull) can lead to symptoms such as nausea, vomiting, and/or lethargy.
  
• Increased bleeding after surgery or trauma is characteristic of hemophilia.

hemophilia causes

As mentioned above, hemophilia is caused by a genetic mutation. The mutations involve genes that code for proteins that are essential in the blood clotting process. The bleeding symptoms arise because blood clotting is impaired.
The process of blood clotting involves a series of complex mechanisms, usually involving 13 different proteins classically termed I through XIII and written with Roman numerals. If the lining of the blood vessels becomes damaged, platelets are recruited to the injured area to form an initial plug. These activated platelets release chemicals that start the clotting cascade, activating a series of 13 proteins known as clotting factors. Ultimately, fibrin is formed, the protein that crosslinks with itself to form a mesh that makes up the final blood clot. The protein involved with hemophilia A is factor VIII (factor 8) and with hemophilia B is factor IX (factor 9).

What is a stroke

A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke) or by hemorrhage (a hemorrhagic stroke). The former, ischemia, is a reduction of blood flow due to occlusion (an obstruction). The latter, hemorrhagic stroke, occurs when a blood vessel in the brain bursts, spilling blood into the spaces surrounding the brain cells or when a cerebral aneurysm ruptures. Stroke is literally a "brain attack",
caused when the vital supply of blood and oxygen is cut off to part of the brain. If a portion of the brain loses its supply of nutrient-rich blood and oxygen, the bodily functions controlled by that part of the brain (vision, speech, walking, etc.) are impaired. Like a heart attack, every minute counts in getting a stroke victim emergency medical treatment so that brain damage and possible future disability will be minimized.

What is atrial fibrillation

Atrial fibrillation (AF) is an electrical rhythm disturbance of the heart affecting the atria. Abnormal electrical impulses in the atria cause the muscle to contract erratically and pump blood inefficiently. The atrial chambers are thus not able to completely empty blood into the ventricles.
Pooling of blood in the atria can cause red blood cells to stick together and form a clot. Most clots within the heart form in a portion of the left atrium known as the left atrial appendage. The most worrysome complication of atrial fibrillation is dislodgement of a clot and embolism of the clot material to one of the major organs of the body (e.g., the brain).
A clot that embolizes to the brain can interrupt blood flow to a portion of the brain, resulting in a cerebrovascular accident, more commonly known as a stroke. Most individuals with atrial fibrillation are advised by their doctors to take one of a number of medications to prevent clot formation within the heart (and therefore reduce the risk of stroke secondary to clot embolism from the heart). The most commonly used medications are warfarin and aspirin. Atrial fibrillation is the most common form of irregular heartbeat (arrhythmia). Normally, your heart's electrical system controls the rhythm at which your heart beats. See illustrations of the heart and its electrical system .

aortic aneurysm

The aorta carries oxygen-rich blood to the body, and is therefore called an artery. Because the aorta is an artery, its walls are made of up three layers; a thin inner layer, a muscular middle layer (that gives the vessel its flexibility under pressure from the filling blood), and a fiber-like outer layer that gives the vessel strength to not burst when the heart pumps blood to the body. Aortic aneurysms occur when a weakness develops in part of the wall of the aorta; three basic types are usually found. If all three layers of the vessel are affected and weakness develops along an extended area of the vessel, the weakened area will appear as a large, bulging region of blood vessel; this is called a fusiform aneurysm. If weakness develops between the inner and outer layers of the aortic wall, a bulge results as blood from the interior of the vessel is pushed around the damaged region in the wall and collects between these layers. This is called a dissecting aneurysm because one layer is "dissected" or separated from another. If damage occurs to only the middle (muscular) layer of the vessel, a sack-like bulge can form; therefore, this is a saccular aneurysm.

Heart valve replacement

Heart valve disease occurs when a valve doesn't work right. A valve may not open all the way. Or, a valve may have problems closing. If this happens, blood doesn't move through the heart's chambers the way it should. If a valve doesn't open all the way, less blood moves through to the next chamber. If a valve doesn't close tightly, blood may leak backward. These problems may mean that the heart must work harder to pump the same amount of blood. Or, blood may back up in the lungs
or body because it's not moving through the heart as it should. Stenosis occurs when a valve doesn't open fully. The valve may have become hardened or stiff with calcium deposits or scarring. So, it's hard to push open. Blood has to flow through a smaller opening, so less blood gets through the valve into the next chamber. Insufficiency (also called regurgitation) results when the valve doesn't close tightly. The valve's supportive structures may be loose or torn. Or, the valve itself may have stretched or thinned. Blood may then leak back the wrong way through the valve.

cardiac arrhythmia

Cardiac arrhythmia is a term that denotes a disturbance of the heart rhythm. Cardiac arrhythmias can range in severity from entirely benign to immediately life-threatening. If arrhythmia is suspected, a cardiologist should be consulted for confirmation. In addition, the use of natural substances for arrhythmia should always be supervised by a doctor. A cardiac
arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. Several forms of cardiac arrhythmia are life-threatening and a medical emergency. A rhythm of the heart at a rate of more than 100 beats/minute is considered a tachycardia. If the ventricles of the heart sustain a tachycardia for a sustained period of time, there can be deleterious effects. Individuals may sense a tachycardia as a pounding sensation of the heart; this is known as "palpitations". However, strictly speaking, palpitations are any sensation of an individual's own heart beat, and can occur at rates less than 100 beats/minute. The causes of tachycardias are numerous, and include stress, ingested or injected substances (ie: caffeine, alcohol, hyperthyroidism, or various drugs). Individuals who have a tachycardia are often advised to limit or remove exposure to any causative agent. A slow rhythm, known as bradycardia (less than 60 beats/min), is usually not life threatening, but may cause symptoms. Either arrhythmia requires medical attention to evaluate the risks associated with the arrhythmia.

What is cardiomyopathy

Cardiomyopathy is an alteration in the function of the heart muscle. It can occur for several reasons in cats and it can take several forms. When the muscle is sufficiently affected that it can not function properly, heart failure occurs. Cardiomyopathy is the deterioration of the cardiac muscle of the heart wall. Cardiomyopathies can generally be categorized into two groups:
ischemic cardiomyopathy and nonischemic cardiomyopathy. Nonischemic cardiomyopathy is weakness in the muscle of the heart that is not due to coronary artery disease. To make a diagnosis of nonischemic cardiomyopathy, significant coronary artery disease should be ruled out. The term nonischemic cardiomyopathy does not describe the etiology of weakened heart muscle. The nonischemic cardiomyopathies are a mixed-bag of disease states, each with their own causes.

coronary atherosclerosis

Atherosclerosis is a type of arteriosclerosis caused by a build-up of plaque in the inner lining of an artery. (Arteriosclerosis is a general term for thickening or hardening of the arteries.) Plaque is made up of deposits of fatty substances, cholesterol, cellular waste products, calcium, and fibrin, and can develop in medium or large arteries. The artery wall becomes thickened
and looses its elasticity. Atherosclerosis is a disease of arterial blood vessels. Venous vessels are not involved unless surgically moved to function as an artery. Atherosclerosis is commonly referred to as a "hardening of blood vessels", but this is an over-simplification. Vascular lesions known as atheromatous plaques or atheromata (singular: atheroma) are formed in the vessel wall, and in late stages may reduce or restrict blood flow in the lumen. When the inner covering of an unstable atheroma breaks, compromising the structural integrity of the internal artery wall, the break may allow hemorrhage into the plaque, generate stenosis, embolism, (very rarely even hemorrhage beyond the artery wall), sometimes leading to severe morbidity and even death.

heart attack (myocardial infarction)

A heart attack (also known as a myocardial infarction) is the death of heart muscle from the sudden blockage of a coronary artery by a blood clot. Coronary arteries are blood vessels that supply the heart muscle with blood and oxygen. Blockage of a coronary artery deprives the heart muscle of blood and oxygen, causing injury to the heart muscle. Injury to the heart muscle causes chest pain and pressure. If blood flow is not restored within 20 to 40 minutes, irreversible death of the heart muscle will begin to occur. Muscle continues to die for 6-8 hours at which time the heart attack usually is "complete." The dead heart muscle is replaced by scar tissue.
The heart is a muscular pump located in the chest. Its job is to pump blood around the body via the circulatory system of blood vessels. The heart consists of 4 chambers: right atrium and right ventricle, and left atrium and left ventricle. Blood is depleted of oxygen after circulating through the body. This blood returns into the right atrium. From there the blood flows into the right ventricle, which pumps the blood out to the lungs for oxygenation. The oxygen-rich blood then returns to the left
atrium. From there it flows into the left ventricle and is pumped out at high pressure into the arteries. The high pressure is generated by powerful contraction of the heart muscle.This raises the pressure of the blood and enables it to flow through the extensive network of arteries to every part of the body and return to the heart. For this pumping action, the heart has to be strong. The heart is nourished by the blood supplied directly to the heart muscle through the coronary arteries. The strength of the heart muscle depends very much on this blood supply. The coronary arteries are usually strong, elastic, and quite flexible. The inner lining of the arteries is normally smooth. This allows the blood to flow smoothly without clotting.

coronary artery disease

Coronary artery disease is a type of heart disease. The coronary arteries are blood vessels that carry blood and oxygen to the heart muscle. When these arteries become clogged with fatty deposits called plaque, it is called coronary artery disease (CAD). Coronary artery disease is sometimes called coronary heart disease (CHD). Clogged arteries can keep the heart
from getting enough blood and oxygen and can cause chest pain (angina). If a blood clot forms, it can suddenly cut off blood flow in the artery and cause a heart attack. Plaque forms in the arteries over many years in a process called atherosclerosis. One cause of plaque in the arteries is too much cholesterol in the blood. As plaque builds up, the artery opening gradually narrows and becomes clogged. The artery can also become less elastic (called "hardening of the arteries").

Heart transplant

A heart transplant is performed to treat heart failure due to disease or injury. A donor heart is removed from a person deemed brain dead. The heart is then transplanted into the recipient.
In general, patients with advance heart failure, on maximal medical therapy should be considered for transplant evaluation. Patients with increasing medication requirements, frequent hospitalizations, or overall deterioration of clinical status should be referred for evaluation. Some causes of heart failure that result in cardiac transplantation are primary cardiomyopathy, coronary artery disease, with either resultant ischemic cardiomyopathy and symptoms of congestive heart failure or inoperable ischemic heart disease with refractory chest discomfort or arrhythmia.
A small percentage of patients who undergo cardiac transplantation do so for idiopathic dialated cardiomyopathy, valvular heart disease, congenital heart disease and inoperable hypertrophic cardiomyopathy. All candidates for transplantation enter the program with a comprehensive series of tests conducted by our multidisciplinary team of specialists. Some of these tests are required for any operative procedure (history and physical chest x-ray EKG etc.) while others (such as specific blood tests) are required for transplantation surgery.

Diagnostic tests and procedures

Echocardiogram

The echocardiogram is an ultrasound of the heart. Using standard ultrasound techniques, two-dimensional slices of the heart can be imaged. An echocardiogram is a painless procedure that uses sound waves and a computer to look at your beating heart. A device called a transducer sends high-frequency sound waves into your chest. The sound waves bounce (echo) off your heart. A computer uses the echoes to create a moving picture of the heart. Echocardiogram works well for most patients and allows doctors to see the heart beating and to visualize many of the structures of the heart.

Cardiac stress test

A cardiac stress test is performed to evaluate the ability of arterial blood flow to the left ventricular heart muscle, to increase with exercise, as compared to resting blood flow rates, and some indication of overall physical fitness. The test is not capable of detecting the presence/absence of the atheroma lesions of atherosclerosis, thus usually misses disease which most commonly produces future angina or heart attack events. Also, it is not designed to evaluate the presence or influences of emotional stresses, even though these probably play a role in heart attacks. The stress test is used to check both overall physical exercise capacity and is generally able to detect high grade, 75% or greater stenosis of the coronary arteries supplying the cardiac muscle.

Electrocardiogram (ECG or EKG)

Electrocardiogram (ECG or EKG) is a painless process that records the heart's electrical activity. Small metal electrodes are placed on the person's wrists, ankles and chest. The electrical signals travel from the electrodes through wires to the EKG machine, which transforms the signals into patterns or waves. Different waves represent different areas of your heart through which electrical currents flow. These current cause the heart muscles to contract and relax. The P wave represents the current in the upper chambers of the heart (atria); the QRS complex represents current in the lower heart chambers (ventricles); and the T wave represents the heart's brief "rest period" as it recharges electrically (repolarizes) between heartbeats.

Devices used in cardiology

Pacemaker

A pacemaker is a medical device designed to regulate the beating of the heart. The purpose of an artificial pacemaker is to stimulate the heart when either the heart's native pacemaker is not fast enough or if there are blocks in the heart's electrical conduction system preventing the propagation of electrical impulses from the native pacemaker to the lower chambers of the heart, known as the ventricles. Generally, pacemakers do not treat fast rhythms of the heart. External pacemakers can be used for initial stabilization of a patient, but implantation of a permanent internal pacemaker is usually required for most conditions.

Automated external defibrillators

Automated External Defibrillators (AEDs) are a proved method of reducing morbidity and mortality from acute myocardial infarction (heart attack). The most common lethal arrhythmias in adult cardiac arrest can be cured by electricity; early defibrillation is a nationally recognized standard of care. To provide a realistic chance of survival, defibrillation must be available soon after cardiac arrest. An automated external defibrillator (AED) detects and treats cardiac arrest due to the cardiac arrhythmias, ventricular fibrillation (VF) and ventricular tachycardia (VT). Uncorrected, these arrhythmias rapidly lead to irreversible brain damage and death.

Congenital heart disease

Atrial septal defect

An atrial septal defect (ASD) is a group of congenital heart diseases that involve the inter-atrial septum of the heart. The inter-atrial septum is the tissue that separates the right and left atria from each other. Without this septum, or if there is a defect in this septum, it is possible for blood to travel from the left side of the heart to the right side of the heart, or the other way around. There are many types of atrial septal defects. They are differentiated from each other by whether they involve other structures of the heart and how they are formed during the developmental process during early fetal development.

Ventricular septal defect

A ventricular septal defect is an opening in the ventricular septum, or dividing wall between the two lower chambers of the heart known as the right and left ventricles. VSD is a congenital (present at birth) heart defect. As the fetus is growing, something occurs to affect heart development during the first 8 weeks of pregnancy, resulting in a VSD. Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta.

Patent ductus arteriosus

Patent ductus arteriosus (PDA) is a congenital heart defect wherein a child's ductus arteriosus fails to close after birth. Symptoms include shortness of breath and cardiac arrhythmia, and may progress to congestive heart failure if left uncorrected. In the developing fetus, the ductus arteriosus (DA) is a shunt connecting the pulmonary artery to the aortic arch that allows much of the blood from the right ventricle to bypass the fetus' fluid-filled lungs. During fetal development, this shunt protects the lungs from being overworked and allows the right ventricle to strengthen.

Heart valve disorders

Aortic valve disease

The aortic valve is one of the valves of the heart. It lies between the left ventricle and the aorta. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. An aortic valve disorder usually does not cause any symptoms in its early stages. As the problem progresses, it may produce shortness of breath, angina (chest pain), light-headedness, dizziness, and even fainting, especially upon exertion.

Aortic insufficiency

Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. The aortic valve separates the left ventricle of the heart (the heart's largest pumping chamber) from the aorta, the large artery that carries oxygen-rich blood out of the left ventricle to the rest of the body. In aortic valve insufficiency, the aortic valve becomes leaky, causing blood to flow backwards into the left ventricle.

Aortic aneurysm

Aortic aneurysms occur when a weakness develops in part of the wall of the aorta; three basic types are usually found. If all three layers of the vessel are affected and weakness develops along an extended area of the vessel, the weakened area will appear as a large, bulging region of blood vessel; this is called a fusiform aneurysm. If weakness develops between the inner and outer layers of the aortic wall, a bulge results as blood from the interior of the vessel is pushed around the damaged region in the wall and collects between these layers.

Myocardium disorders

Cardiomyopathy

Cardiomyopathy is an alteration in the function of the heart muscle. It can occur for several reasons in cats and it can take several forms. When the muscle is sufficiently affected that it can not function properly, heart failure occurs. Cardiomyopathy is the deterioration of the cardiac muscle of the heart wall. Cardiomyopathies can generally be categorized into two groups: ischemic cardiomyopathy and nonischemic cardiomyopathy. Nonischemic cardiomyopathy is weakness in the muscle of the heart that is not due to coronary artery disease.

Congestive heart failure

Congestive heart failure (CHF) (also called heart failure) is the inability of the heart to pump blood effectively to the body, or requiring elevated filling pressures in order to pump effectively. Congestive heart failure occurs when the heart is unable to pump blood effectively throughout the body. The term congestive is used because lung congestion causes some of the main symptoms of heart failure. Heart failure does not mean that your heart has stopped working completely. It means that the heart is not pumping as strongly as it should.

Rheumatic heart disease

Rheumatic heart disease is a complication of rheumatic fever. Rheumatic fever, which results from an untreated strep throat, can damage the heart valves, causing them to fail to close properly or not open enough. When a valve fails to close properly, it allows blood to leak backward. When a valve does not open enough, the heart must pump harder to force blood through the narrowed opening. When damage to the heart is permanent, the condition is called rheumatic heart disease. Rheumatic fever is an acute infectious disease that occurs primarily in children and young adults.

Endocarditis

Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves (native or prosthetic valves). Other structures which may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices. Endocarditis is characterized by a prototypic lesion, the vegetation, which is a mass of platelets, fibrin, microcolonies of microorganisms, and scant inflammatory cells. In the subacute form of infective endocarditis, the vegetation may also include a center of granulomatous tissue, which may fibrose or calcify. There are multiple ways to classify endocarditis. The simplest classification is based on etiology: either infective or non-infective, depending on whether a microorganism is the source of the inflammation. Regardless, diagnosis of endocarditis is based on the clinical features, investigations such as echocardiogram, as well as any blood cultures demonstrating the presence of endocarditis-causing microorganisms.

Heart Infection

Causes, Incidence, And Risk Factors

Heart failure is a chronic, long-term condition, although it can sometimes develop suddenly.
The condition may affect only the right side or only the left side of the heart. These are called right-sided heart failure or left-sided heart failure. More often, both sides of the heart are involved.
Heart failure is present when the following changes are present:

• Your heart muscle cannot pump, or eject, the blood out of the heart very well. This is called systolic heart failure.
• Your heart muscles are stiff and do not fill up with blood easily. This is called diastolic heart failure.

Both of these problems mean the heart is no longer able to pump enough oxygen-rich blood out to the rest of your body, especially when you exercise or are active.
As the heart's pumping action is lost, blood may back up in other areas of the body, causing fluid to build up in the lungs, the liver, the gastrointestinal tract, and the arms and legs. As a result, there is a lack of oxygen and nutrition to organs, which damages them and reduces their ability to work properly.
Perhaps the most common cause of heart failure is coronary artery disease (CAD), a narrowing of the small blood vessels that supply blood and oxygen to the heart. For information on this condition and its risk factors,