The Heart

Mar 19, 2012 , Translated by Kristina Knazko

2-srdce.jpg - kopie
2-srdce.jpg - kopie
The heart is among the most vital organs of the human body. It constantly pumps blood into arteries and ensures the transport of nutrients and oxygen to tissues as well as diverts waste away. The heart is divided into two halves, the left and right hearts. Each half is divided into an atrium and a ventricle. Nowadays, cardiovascular diseases are responsible for over half the deaths in developed countries.

The Heart

The heart is one on the vital organs of the human body. It functions as a pump, which means it forces blood to reach all the tissues and organs in the human body, and then return back to the heart. The blood supplies organs with oxygen and vital nutrients, and diverts waste away. The heart contracts about 72 times every minute, therefore it consists mostly of muscle tissue allowing these contractions.

The Heart and its Chambers

The heart is situated behind the sternum, 2/3 on the left side. It is different in size for every individual, reaching about the size of a male hand and weighing approximately 350 to 400 grams (770 to 880 pounds). Functionally, the heart is divided into 2 parts, the left and right side. Each side consists of an atrium and a ventricle, separated by valves that open and close with cardiac action. The right side receives deoxygenated blood from the body through the superior and inferior venae cavae, which is further transported through the pulmonary artery into the lungs, where the blood is oxygenated. The blood is then transported by four pulmonary veins from the lungs into the left heart, and from there into the aorta and into general circulation. Blood vessels leading into the heart are called veins, and vessels leading away from the heart are called arteries.

Heart Function

Beating of the heart is its main function. There are two parts to a heartbeat, the systole and diastole. During systole, the heart muscle contracts causing the expulsion of accumulated blood, and with diastole the muscle relaxes, allowing more blood to flow into the heart. These contractions and relaxations are regulated by the heart itself; it has its own apparatus that generates electrical impulses and activate the muscle. These spread with the help of a special connection called the cardiac conduction system. This significantly differs from other organs, which need commands from the brain to perform their function. In the case of the heart, the brain can only influence the frequency of these impulses and force of the contractions. In many situations it is necessary to increase the rate of blood being pumped, such as during physical activity, when tissues consume more oxygen and nutrients.

Supplying the Heart with Oxygen

The heart itself consumes a significant amount of oxygen and nutrients and it does not receive much from the blood flowing through its chambers, therefore it is supplied from the outside by the coronary arteries. If the flow of blood through the coronary arteries is somehow restricted, the cells of the heart muscle are in danger of being damaged, often leading to a heart attack; where these cells die and the heart is irreversibly damaged.

The Most Common Heart Conditions

The heart is a vital organ without which one cannot survive. One should take good care of it because even this organ can be often affected by various diseases, some of which can become fatal. The most common heart conditions include myocardial infarction (heart attack), angina pectoris, cardiomyopathy and arrhythmia.

Myocardial Infarction

Myocardial infarction, or heart attack, indicates the death of most of the parts of the heart due to constricted blood flow. During a heart attack, vessels that carry blood to tissues are blocked, resulting in the cells not receiving enough oxygen and nutrients and eventually dying. Blockage is usually caused by atherosclerosis, thrombosis or embolism.

  • Myocardial infarction is manifested by a number of symptoms. Among the most important is severe pain in the chest and heart area, whose intensity does not depend on the positioning of the individual. Patients often experience radiating pain into the left upper arm, neck, left half of the jaw or shoulder blades. The patient tends to experience pallor, anxiety, shortness of breath (dyspnea) and cold sweats.
  • Myocardial infarction can cause a number of unpleasant consequences, where the most severe or late-treated cases can be the immediate cause of death. Other consequences of a heart attack include arrhythmia, inflammation of the pericardium (pericarditis), left ventricular failure and a lack of blood supply to the body. Possible consequences include rupturing of the heart wall, i.e. the emergence of cardiac tamponade.
  • The basic treatment of myocardial infarction remains in leading a healthy balanced lifestyle. Modifying one's diet and getting the recommended amount of exercise provides a great service for the heart as well as the whole body. Treatment of myocardial infarction however, must include pharmacotherapy, i.e. the administration of medication. Medications from different groups need to be prescribed. These include medication to lower blood pressure, usually ACE-inhibitors or ARBs. Furthermore, medications to lower heart rate, i.e. beta-blockers are given. It is also necessary that the patient takes acetylsalicylic acid (aspirin) to thin the blood and prevent blood clots, as well as statins, which lower cholesterol levels in the blood.

Angina Pectoris

Angina pectoris is a condition manifested by gripping chest pain. Angina is caused by an insufficient supply of oxygenated blood in the cells of the heart, however the amount is still not low enough to cause myocardial infarction. The pain can spread to the neck, shoulder or jaw. According its manifestations, stable angina, unstable angina and special forms of angina can be distinguished.

  • Stable angina pectoris, also known as exertional angina, manifests itself regularly during exertion, when there is increased stress on the heart and there is a higher demand of oxygenated blood. Narrowed arteries due to atherosclerosis do not have the ability to carry enough oxygenated blood to the heart, and this causes an attack of angina pectoris. The treatment is mainly pharmacological; patients are prescribed nitrates to ensure the expansion of blood vessels, such as nitroglycerin. Beta-blockers, usually in combination with acetylsalicylic acid, are also administered as they lower heart rate and thin blood to help prevent blood clots.
  • Unstable angina pectoris is a very dangerous and an immediate threat to human life. It manifests itself as attacks of pain, unrelated to exertion. The causes of the reduced supply of oxygenated blood are unstable blood clots that spontaneously crack and close the blood vessel, even if not to the same extent as during myocardial infarction. Unstable angina directly precedes the emergence of a heart attack and is therefore known as a pre-heart attack condition. Treatment of unstable angina is very different from the first type in that hospitalization of the patient is necessary. The patient's veins are injected with anticoagulants; medication to reduce clotting. Most often, this medication is the publicly know heparin. Further treatment is the same as with stable angina. Acetylsalicylic acid can also be administered, nitrates can be injected into the veins and a coronary angiography must be performed on every patient suffering from unstable angina pectoris.

Cardiomyopathy

Cardiomyopathy is a group of illnesses that result in the failure of cardiac function. Cardiomyopathy can be present for a long time without manifesting any signs or symptoms. Sometimes it is present for a while, and other times the condition arises suddenly and is the cause of immediate death of an otherwise healthy, young individual. Cardiomyopathy can emerge as a result of various infections affecting the heart, defect of the valves of the heart or due to ischemic heart disease. Cardiomyopathy tends to affect individuals who consume alcohol frequently. Tendency to develop cardiomyopathy can also be caused by hereditary factors, though in most cases of cardiomyopathy the cause is unknown.

  • Symptoms of cardiomyopathy depend on its type, whether one is dealing with a stretched or thickened myocardium. This indicates dilated, or hypertrophic, cardiomyopathy. In short, this condition can be described as the heart slowly ceasing to fulfill its function, leading to heart failure. This is manifested by dyspnea (shortness of breath), fatigue, decreased performance, swelling of the lower limbs, loss of consciousness or and/or chest pain. Hypertrophic cardiomyopathy, where the walls are thickened, can be asymptomatic. Because a part of the myocardium includes the electrical system which ensures the functioning of the heart, cardiomyopathy is usually accompanied by arrhythmia, irregular beating of the heart. In the affected heart, there is a higher tendency to develop blood clots, which can be expelled from the heart and lodged in the brain, causing a stroke. Heart failure can lead to immediate death.
  • Treatment of dilated cardiomyopathy is based on pharmacotherapy. Medications from different groups are administered, primarily medication to lower blood pressure as well as reduce heart rate. In the event of blood stasis, diuretics are prescribed. The treatment of hypertrophic cardiomyopathy involves physical calm for the patient and effective medication. Patients take diuretics to lower blood pressure and excrete excess fluid from the body. It is also necessary to administer antiarrhythmics and medication to lower heart rate. In patients with the hypertrophic form of cardiomyopathy at risk of sudden death, a cardioverter-defibrillator is preventatively implanted. A cardioverter-defibrillator is a special device that stimulates the heart to contract. In the most severe cases, the patient may be a candidate for an artificial heart and a heart transplant.

Arrhythmia

Arrhythmia consists of a number of diseases that cause the regular beating of the heart to be disrupted. One of the most common types of arrhythmias is atrial fibrillation. With atrial fibrillation, the sinus node is malfunctioning and the impulse does not spread throughout the heart, as it appears in other cells of the atrium, and therefore causes the electrical activity of the atrium to be chaotic. The disordered impulses thus circulate continuously, resulting in the atria to fibrillate instead of contract normally.

  • Manifestations of atrial fibrillation include irregular heartbeats of varying force, and heart palpitations. Other symptoms include dyspnea, fatigue, chest pain, and nausea. Dizziness can also occur, as well as loss of consciousness due to insufficient cerebral circulation. Some patients suffering from atrial fibrillation do not experience any symptoms until complications develop. During atrial fibrillation, blood accumulates in the atria and can cause blood clots. These blood clots may cause an embolism in the brain or other organs.
  • The treatment of atrial fibrillation is focused on preventing the formation of random impulses, resynchronizing the heart cells and restoring function to the main impulse generator, i.e. the sinus node. This is done with the help of an electrical cardioversion; where electrodes with brief electric shocks are applied to the heart, stopping the spread of the impulse and cancelling all areas where the impulses develop, making the heart cells obey the instructions of the sinus node. This procedure is performed under brief general anesthetic. The other option of eliminating the fibrillations is with the help of antiarrhythmic medication.

Risks of Cardiovascular Diseases

The correct function of the heart is vital, though nowadays heart conditions appear more and more often. The rise in obesity is the main cause of this, where meals consist of excessive amounts of fats. Other significant risk factors include smoking and a lack of physical activity. The combination of these factors are responsible for the higher incidence of atherosclerosis, hardening of the arteries, which is the main cause of cardiovascular diseases. Cardiovascular diseases are the number one cause of death worldwide; more people die from these diseases than from any other cause each year. The branch of medicine dealing with the heart, its structure, function and diseases is called cardiology.

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