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Branch of medicine dealing with the heart
the medical speciality

Cardiology is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease, and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.

All cardiologists in the branch of medicine study the disorders of the heart, but the study of adult and child heart disorders each require different training pathways. Therefore, an adult cardiologist (often simply called "cardiologist") is inadequately trained to take care of children, and pediatric cardiologists are not trained to treat adult heart disease. Surgical aspects outside of cardiac rhythm device implant are not included in cardiology and are in the domain of cardiothoracic surgery. For example, coronary artery bypass surgery (CABG), cardiopulmonary bypass and valve replacement are surgical procedures performed by surgeons, not cardiologists. However, some invasive procedures such as cardiac catheterization and pacemaker implantation are performed by cardiologists.

Cardiology is a specialty of internal medicine. To become a cardiologist in the United States, a three year residency in internal medicine is followed by a three year fellowship in cardiology. It is possible to specialize further in a sub specialty. Recognized sub specialties in the U. S. by the Accreditation Council for Graduate Medical Education are cardiac electrophysiology, echocardiography, interventional cardiology, and nuclear cardiology. Recognized subspecialties in the U. S. by the American Osteopathic Association Bureau of Osteopathic Specialists include clinical cardiac electrophysiology and interventional cardiology. In India, a three year residency in General Medicine or Pediatrics after M. B. B. S. and then three years of residency in cardiology are needed to be a D. M. (holder of a Doctorate of Medicine [D. M.])/Diplomate of National Board (DNB) in Cardiology. Per Doximity, adult cardiologists earn an average of $436,849 per year in the U. S.

Cardiac electrophysiology is the science of elucidating, diagnosing, and treating the electrical activities of the heart. The term is usually used to describe studies of such phenomena by invasive (intracardiac) catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical stimulation (PES). These studies are performed to assess complex arrhythmias, elucidate symptoms, evaluate abnormal electrocardiograms, assess risk of developing arrhythmias in the future, and design treatment. These procedures increasingly include therapeutic methods (typically radiofrequency ablation, or cryoablation) in addition to diagnostic and prognostic procedures. Other therapeutic modalities employed in this field include antiarrhythmic drug therapy and implantation of pacemakers and automatic implantable cardioverter defibrillators (AICD). The cardiac electrophysiology study typically measures the response of the injured or cardiomyopathic myocardium to PES on specific pharmacological regimens in order to assess the likelihood that the regimen will successfully prevent potentially fatal sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in the future. Sometimes a series of electrophysiology study drug trials must be conducted to enable the cardiologist to select the one regimen for long term treatment that best prevents or slows the development of VT or VF following PES. Such studies may also be conducted in the presence of a newly implanted or newly replaced cardiac pacemaker or AICD. The training required to become an electrophysiologist is long and requires eight years after medical school (within the U. S.). Three years of internal medicine residency, three years of cardiology fellowship, and two years of clinical cardiac electrophysiology.

Cardiogeriatrics, or geriatric cardiology, is the branch of cardiology and geriatric medicine that deals with the cardiovascular disorders in elderly people. Cardiac disorders such as coronary heart disease, including myocardial infarction, heart failure, cardiomyopathy, and arrhythmias such as atrial fibrillation, are common and are a major cause of mortality in elderly people. Vascular disorders such as atherosclerosis and peripheral arterial disease cause significant morbidity and mortality in aged people.

Cardiac imaging includes echocardiography (echo), cardiac magnetic resonance imaging (CMR), and computed tomography of the heart. Those who specialize in cardiac imaging may undergo more training in all imaging modes or focus on a single imaging modality. Echocardiography (or "echo") uses standard two dimensional, three dimensional, and Doppler ultrasound to create images of the heart. Those who specialize in echo may spend a significant amount of their clinical time reading echos and performing transesophageal echo, in particular using the latter during procedures such as insertion of a left atrial appendage occlusion device. Cardiac MRI utilizes special protocols to image heart structure and function with specific sequences for certain diseases such as hemochromatosis and amyloidosis. Cardiac CT utilizes special protocols to image heart structure and function with particular emphasis on coronary arteries.

Interventional cardiology is a branch of cardiology that deals specifically with the catheter based treatment of structural heart diseases. A large number of procedures can be performed on the heart by catheterization, including angiogram, angioplasty, atherectomy, and stent implantation. These procedures all involve insertion of a sheath into the femoral artery or radial artery (but, in practice, any large peripheral artery or vein) and cannulating the heart under X ray visualization (most commonly fluoroscopy). This cannulation allows indirect access to the heart, bypassing the trauma caused by surgical opening of the chest. The main advantages of using the interventional cardiology or radiology approach are the avoidance of the scars and pain, and long post operative recovery. Additionally, interventional cardiology procedure of primary angioplasty is now the gold standard of care for an acute myocardial infarction. This procedure can also be done proactively, when areas of the vascular system become occluded from atherosclerosis. The Cardiologist will thread this sheath through the vascular system to access the heart. This sheath has a balloon and a tiny wire mesh tube wrapped around it, and if the cardiologist finds a blockage or stenosis, they can inflate the balloon at the occlusion site in the vascular system to flatten or compress the plaque against the vascular wall. Once that is complete a stent is placed as a type of scaffold to hold the vasculature open permanently.

A relatively newer specialization of cardiology is in the field of heart failure and heart transplant. Specialization of general cardiology to just that of the cardiomyopathies leads to also specializing in heart transplant and pulmonary hypertension. Cardiomyopathy is a heart disease of the heart muscle, where the heart muscle becomes inflamed and thick.

A recent specialization of cardiology is that of cardiooncology. This area specializes in the cardiac management in those with cancer and in particular those with plans for chemotherapy or those who have experienced cardiac complications of chemotherapy.

In recent times, the focus is gradually shifting to preventive cardiology due to increased cardiovascular disease burden at an early age. According to the WHO, 37% of all premature deaths are due to cardiovascular diseases and out of this, 82% are in low and middle income countries. Clinical cardiology is the sub specialty of cardiology which looks after preventive cardiology and cardiac rehabilitation. Preventive cardiology also deals with routine preventive checkup though noninvasive tests, specifically electrocardiography, fasegraphy, stress tests, lipid profile and general physical examination to detect any cardiovascular diseases at an early age, while cardiac rehabilitation is the upcoming branch of cardiology which helps a person regain their overall strength and live a normal life after a cardiovascular event. A subspecialty of preventive cardiology is sports cardiology. Because heart disease is the leading cause of death in the world including United States (cdc. gov), national health campaigns and randomized control research has developed to improve heart health.

Helen B. Taussig is known as the founder of pediatric cardiology. She became famous through her work with Tetralogy congenital heart defect in which oxygenated and deoxygenated blood enters the circulatory system resulting from a ventricular septal defect (VSD) right beneath the aorta. This condition causes newborns to have a bluish tint, cyanosis, and have a deficiency of oxygen to their tissues, hypoxemia. She worked with Alfred Blalock and Vivien Thomas at the Johns Hopkins Hospital where they experimented with dogs to look at how they would attempt to surgically cure these "blue babies". They eventually figured out how to do just that by the anastomosis of the systemic artery to the pulmonary artery and called this the Blalock Taussig Shunt. Tetralogy of Fallot, pulmonary atresia, double outlet right ventricle, transposition of the great arteries, persistent truncus arteriosus, and Ebstein's anomaly are various congenital cyanotic heart diseases, in which the blood of the newborn is not oxygenated efficiently, due to the heart defect.

As more children with congenital heart disease are surviving into adulthood, a hybrid of adult & pediatric cardiology has emerged called adult congenital heart disease (ACHD). This field can be entered as either adult or pediatric cardiology. ACHD specializes in congenital diseases in the setting of adult diseases (e. g., coronary artery disease, COPD, diabetes) that is, otherwise, atypical for adult or pediatric cardiology.

As the center focus of cardiology, the heart has numerous anatomical features (e. g., atria, ventricles, heart valves) and numerous physiological features (e. g., systole, heart sounds, afterload) that have been encyclopedically documented for many centuries. The heart is located in the middle of the abdomen with its tip slightly towards the left side of the abdomen. Disorders of the heart lead to heart disease and cardiovascular disease and can lead to a significant number of deaths: cardiovascular disease is the leading cause of death in the U. S. and caused 24.95% of total deaths in 2008. The primary responsibility of the heart is to pump blood throughout the body. It pumps blood from the body — called the systemic circulation — through the lungs — called the pulmonary circulation — and then back out to the body. This means that the heart is connected to and affects the entirety of the body. Simplified, the heart is a circuit of the circulation. While plenty is known about the healthy heart, the bulk of study in cardiology is in disorders of the heart and restoration, and where possible, of function. The heart is a muscle that squeezes blood and functions like a pump. The heart's systems can be classified as either electrical or mechanical, and both of these systems are susceptible to failure or dysfunction. The electrical system of the heart is centered on the periodic contraction (squeezing) of the muscle cells that is caused by the cardiac pacemaker located in the sinoatrial node. The study of the electrical aspects is a sub field of electrophysiology called cardiac electrophysiology and is epitomized with the electrocardiogram (ECG/EKG). The action potentials generated in the pacemaker propagate throughout the heart in a specific pattern. The system that carries this potential is called the electrical conduction system. Dysfunction of the electrical system manifests in many ways and may include Wolff–Parkinson–White syndrome, ventricular fibrillation, and heart block. The mechanical system of the heart is centered on the fluidic movement of blood and the functionality of the heart as a pump. The mechanical part is ultimately the purpose of the heart and many of the disorders of the heart disrupt the ability to move blood. Heart failure is one condition in which the mechanical properties of the heart have failed or are failing, which means insufficient blood is being circulated. Failure to move a sufficient amount of blood through the body can cause damage or failure of other organs and may result in death if severe.

Coronary circulation is the circulation of blood in the blood vessels of the heart muscle (the myocardium). The vessels that deliver oxygen rich blood to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. These include the great cardiac vein, the middle cardiac vein, the small cardiac vein and the anterior cardiac veins. As the left and right coronary arteries run on the surface of the heart, they can be called epicardial coronary arteries. These arteries, when healthy, are capable of autoregulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. These relatively narrow vessels are commonly affected by atherosclerosis and can become blocked, causing angina or myocardial infarction (a. k. a a heart attack). The coronary arteries that run deep within the myocardium are referred to as subendocardial. The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium; there is very little redundant blood supply, which is why blockage of these vessels can be so critical.

The cardiac examination (also called the "precordial exam"), is performed as part of a physical examination, or when a patient presents with chest pain suggestive of a cardiovascular pathology. It would typically be modified depending on the indication and integrated with other examinations especially the respiratory examination. Like all medical examinations, the cardiac examination follows the standard structure of inspection, palpation and auscultation.

Cardiology is concerned with the normal functionality of the heart and the deviation from a healthy heart. Many disorders involve the heart itself, but some are outside of the heart and in the vascular system. Collectively, the two are jointly termed the cardiovascular system, and diseases of one part tend to affect the other.

Coronary artery disease, also known as "ischemic heart disease", is a group of diseases that includes: stable angina, unstable angina, myocardial infarction, and is one of the causes of sudden cardiac death. It is within the group of cardiovascular diseases of which it is the most common type. The first sign is occasionally a heart attack. Risk factors include: high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol, among others. Other risks include depression. The underlying mechanism involves atherosclerosis of the arteries of the heart. A number of tests may help with diagnoses including: electrocardiogram, cardiac stress testing, coronary computed tomographic angiography, and coronary angiogram, among others. Prevention is by eating a healthy diet, regular exercise, maintaining a healthy weight and not smoking. There is limited evidence for screening people who are at low risk and do not have symptoms. Treatment involves the same measures as prevention. In those with stable CAD it is unclear if PCI or CABG in addition to the other treatments improve life expectancy or decreases heart attack risk. In 2013 CAD was the most common cause of death globally, resulting in 8.14 million deaths (16.8%) up from 5.74 million deaths (12%) in 1990. The risk of death from CAD for a given age has decreased between 1980 and 2010 especially in developed countries. The number of cases of CAD for a given age has also decreased between 1990 and 2010. In the U. S. in 2010 about 20% of those over 65 had CAD, while it was present in 7% of those 45 to 64, and 1.3% of those 18 to 45.

Heart failure or formally cardiomyopathy, is the impaired function of the heart and there are numerous causes and forms of heart failure.

Cardiac arrhythmia, also known as "cardiac dysrhythmia" or "irregular heartbeat", is a group of conditions in which the heartbeat is too fast, too slow, or irregular in its rhythm. Most arrhythmias can be effectively treated. Arrhythmia affects millions of people. In Europe and North America, as of 2014, atrial fibrillation affects about 2% to 3% of the population. Atrial fibrillation and atrial flutter resulted in 112,000 deaths in 2013, up from 29,000 in 1990. About 80% of sudden cardiac death is the result of ventricular arrhythmias. If not treated within minutes, death usually occurs. The most common cause of cardiac arrest is coronary artery disease. In the United States, cardiac arrest outside of hospital occurs in about 13 per 10,000 people per year (326,000 cases). In hospital cardiac arrest occurs in an additional 209,000 Cardiac arrest becomes more common with age. Lifestyle factors can increase the risk of hypertension. These include excess salt in the diet, excess body weight, smoking, and alcohol consumption. Blood pressure is expressed by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively. High blood pressure is present if the resting blood pressure is persistently at or above 140/90 mmHg for most adults. When diagnosing high blood pressure, ambulatory blood pressure monitoring over a 24 hour period appears to be more accurate than "in office" blood pressure measurement at a physician's office or other blood pressure screening location. Lifestyle changes and medications can lower blood pressure and decrease the risk of health complications. Lifestyle changes include weight loss, decreased salt intake, physical exercise, and a healthy diet. The treatment of moderate to severe high arterial blood pressure (defined as >160/100 mmHg) with medication is associated with an improved life expectancy and reduced morbidity. The effect of treatment for blood pressure between 140/90 mmHg and 160/100 mmHg is less clear, with some studies finding benefits while others do not. High blood pressure affects between 16% and 37% of the population globally.

Essential hypertension is the form of hypertension that by definition has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients, it tends to be familial and is likely to be the consequence of an interaction between environmental and genetic factors. Prevalence of essential hypertension increases with age, and individuals with relatively high blood pressure at younger ages are at increased risk for the subsequent development of hypertension. Hypertension can increase the risk of cerebral, cardiac, and renal events. Secondary hypertension is a type of hypertension which is caused by an identifiable underlying secondary cause. It is much less common than essential hypertension, affecting only 5% of hypertensive patients. It has many different causes including endocrine diseases, kidney diseases, and tumors. It also can be a side effect of many medications.

Complications of hypertension are clinical outcomes that result from persistent elevation of blood pressure. Hypertension is a risk factor for all clinical manifestations of atherosclerosis since it is a risk factor for atherosclerosis itself. It is an independent predisposing factor for heart failure, coronary artery disease, stroke, and peripheral arterial disease. It is the most important risk factor for cardiovascular morbidity and mortality, in industrialized countries.

A congenital heart defect, also known as a "congenital heart anomaly" or "congenital heart disease", is a problem in the structure of the heart that is present at birth. Signs and symptoms depend on the specific type of problem. Most congenital heart problems do not occur with other diseases. Complications that can result from heart defects include heart failure. Certain cases may be due to infections during pregnancy such as rubella, use of certain medications or drugs such as alcohol or tobacco, parents being closely related, or poor nutritional status or obesity in the mother. Having a parent with a congenital heart defect is also a risk factor. Occasionally heart transplantation is required. They affect between 4 and 75 per 1,000 live births depending upon how they are diagnosed. About 6 to 19 per 1,000 cause a moderate to severe degree of problems. Pulmonary atresia with an intact ventricular septum: This type of pulmonary atresia is associated with complete and intact septum between the ventricles.

There are two different types of transposition of the great arteries, Dextro transposition of the great arteries and Levo transposition of the great arteries, depending on where the chambers and vessels connect. Dextro transposition happens in about 1 in 4,000 newborns and is when the right ventricle pumps blood into the aorta and deoxygenated blood enters the bloodstream. The temporary procedure is to create an atrial septal defect. A permanent fix is more complicated and involves redirecting the pulmonary return to the right atrium and the systemic return to the left atrium, which is known as the Senning procedure. The Rastelli procedure can also be done by rerouting the left ventricular outflow, dividing the pulmonary trunk, and placing a conduit in between the right ventricle and pulmonary trunk. Levo transposition happens in about 1 in 13,000 newborns and is characterized by the left ventricle pumping blood into the lungs and the right ventricle pumping the blood into the aorta. This may not produce problems at the beginning, but will eventually due to the different pressures each ventricle uses to pump blood. Switching the left ventricle to be the systemic ventricle and the right ventricle to pump blood into the pulmonary artery can repair levo transposition.

Persistent truncus arteriosus is when the truncus arteriosus fails to split into the aorta and pulmonary trunk. This occurs in about 1 in 11,000 live births and allows both oxygenated and deoxygenated blood into the body. The repair consists of a VSD closure and the Rastelli procedure.