An Overview of The Heart
The heart is a muscular, fist-sized organ that is located in a space called the mediastinum between the two lungs. It continuously pumps blood, beating as many as 100,000 times a day.
The heart ensures its own oxygen supply through a set of coronary arteries and veins. The heart is also an endocrine organ that produces the hormones atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), which coordinate heart function with blood vessels and the kidneys.
Internally, the heart is essentially hollow. It is divided vertically into two halves by a septum, and each side of the heart has two internal chambers – an atrium on top and a ventricle on the bottom. Venous blood enters the right side of the heart through the right atrium and is pumped by the right ventricle to the lungs, where carbon dioxide is released and oxygen acquired. Oxygenated blood from the lungs is returned to the left atrium and is pumped by the left ventricle into arteries that carry it throughout the body.
Four heart valves regulate the direction and flow of blood through the chambers of the heart. It is their opening and shutting that gives the heart its characteristic “lub-dub” beat. The heart muscle itself is called the myocardium. Lining the chambers of the heart and the valves is a membrane called the endocardium. Encasing the outside of the heart is the pericardium – a layered membrane that is fibrous on the outside and serous (fluid-secreting) on the inside. The pericardium forms a protective barrier around the heart and allows it to beat in a virtually friction-free environment.
Heart disease that is causing few symptoms may be detected during a visit to a health practitioner for nonspecific symptoms such as fatigue. The healthcare provider may order a variety of blood and other tests to investigate possible causes of the person’s symptoms.
Laboratory blood tests
Screening for risk of cardiovascular disease Cardiac risk testing is performed to screen asymptomatic people to help determine their risk of developing coronary heart disease. A cardiac risk assessment is a group of tests and health factors that have been proven to indicate the chance of having a cardiovascular event such as heart attack or stroke. The factors considered include age, family history of heart disease, diet, physical activity, and blood pressure, for example.
Laboratory test may include
Lipid profile (LDL-C,HDL-C, cholesterol, triglycerides)
a group of tests that examine the amount and type of lipids (fats) in the blood
detects low concentrations of C-reactive protein, a marker of inflammation that is associated with atherosclerosis, among other conditions
an additional lipid test that may be used to identify an elevated level of lipoprotein (a), a modification to LDL-C that increases risk of atherosclerosis; the test may be used in conjunction with a routine lipid profile to provide additional information. Several other tests are being studied as potential markers for heart disease.
Diagnosing Heart Attacks
Tests for proteins that are released when muscle cells are damaged, often called cardiac biomarkers, are frequently ordered when someone has symptoms of acute coronary syndrome (ACS), such as chest pain, pain in the jaw, neck, abdomen, back, or that radiates to the shoulder or arms, nausea, shortness of breath, and lightheadedness.