Definition of cardiology:
Cardiology is a medical discipline specializing on diagnostics, therapy, management, prophylaxis and research of diseases affecting the heart and circulatory system. Doctors working within the cardiology are called cardiologists. Cardiologists consult and treat patients suffering from cardiovascular pathologies. These pathologies include heart rhythm disorders (also called arrhythmias), hypertension, heart failure and other heart diseases.
Diagnostic methods used in cardiology
Cardiologists usually use several routine diagnostic tests for diagnosing patients:
- Electrocardiogram (ECG) - a recoding of the electrical activity of the heart, recorded by electrodes placed on the chest wall.
- Holter monitoring - long-term ECG recording, usually lasting 24 hours. This method is used to detect the heart damage signs, rhythm and conduction disorders in a longer period of time.
- Exercise tolerance test or veloergometry - a diagnostics method to evaluate physical tolerance or a load test. Veloergometer resembles fitness equipment similar to a bicycle which is equipped with special hardware for capturing heart`s electrical activity. With the help of the hardware a heart cardiogram, as well as the blood pressure, is registered for a patient during load.
- Echocardiography: an ultrasound method, by which the size of the heart, condition of the heart valves and walls, and the functional status of the heart can be observed. Sometimes echocardiographic examination can be performed through oesophagus.
- Day-night monitoring of the blood-pressure
- Coronarography - cardiovascular examination using contrast substance
Subspecialities of cardiology
- Adult cardiology
- Pediatric cardiology
- Cardiac electrophysiology
- Clinical cardiac electrophysiology
- Interventional cardiology
- Preventive Cardiology and Cardiac Rehabilitation
The most common cardiovascular diseases include:
- Arterial hypertension - long-term medical condition in which the blood pressure in the arteries is persistently elevated. Despite the fact that this disease may be asymptomatic (causing no symptoms), it can cause several major complications and even death.
- Coronary artery disease (CAD, ischemic heart disease) - condition where vessels supplying blood to the heart become narrowed therefore causing ischemia of myocardium. These pathologies often lead to unstable angina, myocardial infarction. According to the WHO, CAD contributes to almost 13% of all deaths globally.
- Cardiac arrythmia - atrial fibrillation, ventricular fibrillation, atrial and ventricular tachycardia, WPW syndrome etc. These pathologies usually are complications of primary heart diseases, such as arterial hypertension, coronary artery disease.
- Congenital heart defects - tetrology of fallot, persistent ductus arteriosus, great vessel transposition, pulmonary atresia, atrial septal defect, ventricular septal defect etc. These pathologies are usualy treated by pediatric cardiologysts and cardiac surgeons.
The heart (latin: cor) is a thick, muscular organ with four cavitated parts located in the middle portion of the inferior mediastinum. The heart acts as a central pump of the cardiovascular system that maintains unidirectional flow of blood.
The heart has a cone shape with the base of the heart directed upward, to the right and posteriorly, while the apex of the heart is directed downward, to the left and anteriorly. The heart is composed of four chambers - two atria (right and left) and two ventricles (right and left). The left atrium and the left ventricle together form the arterial part of the heart, while the right atrium and the right ventricle compose the venous part.
The wall of the heart is formed by three layers - the endocardium (inner layer), myocardium (middle layer) and epicardium (outer layer). The endocardium is the epithelial layer lining all the cavities of the heart, the myocardium is the thick muscular layer formed by cardiac muscles, and the epicardium is a serous membrane of the heart.
The heart is surrounded by a closed fibrous sac called the pericardium. The pericardium has an outer (fibrous) layer and an inner (serous) layer. The serous layer has two lamina - the parietal and the visceral laminae. The visceral lamina of the serous pericardium is the same epicardium that forms the outer layer of the heart. The space between the parietal and visceral laminae of the serous pericardium is called the pericardial cavity, and it contains small amount of serous fluid that decreases the surface tension and lubricates, allowing free movement of the heart during contraction.
The constant and rythmic contractions of the heart are due the conducting system of the heart, with the rythm generating normally in the sinuatrial node. The conducting system coordinates the contractions of the myocardium of the atria and ventricles of the heart. However, the heart rate can be altered by nerve impulses from the sympathetic and parasympathetic parts of the nervous system, which provide innervation to the heart. The parasympathetic nerve fibers supplying the heart originate from the vagus nerve (CN X) and terminate at the sinuatrial and atrioventricular nodes, slowing the heart rate and reducing the force of the heartbeat. The sympathetic innervation comes from the cervical ganglia of the sympathetic trunk via the cardiac nerves, causing the rate and force of cardiac muscle contraction to increase.