Heart Health

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 blood that the heart moves carries oxygen and nutrients throughout the body and transports carbon dioxide and other wastes to the lungs, kidneys, and liver for removal.

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.

Testing

The goals of testing for heart disease are to distinguish between symptoms that are heart-related and those that are due to another condition. Testing is ordered to help determine which heart disease is present, to determine whether the disorder is acute or chronic, to monitor a cardiac event that is in progress such as a heart attack, and to determine the severity and extent of the disease.

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

hs-CRP
detects low concentrations of C-reactive protein, a marker of inflammation that is associated with atherosclerosis, among other conditions

Lp(a)
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

When someone presents to the emergency room with a possible heart attack (acute coronary syndrome, ACS), the person is evaluated with a variety of laboratory blood tests and other tests, such as imaging procedures (see below). These are used to determine the cause of the pain and the severity of the condition. Since some treatments for a heart attack must be given within a short period of time to minimize heart damage, an accurate diagnosis must be quickly confirmed.

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.