basic heart facts

Diagnosing patients with
Coronary Artery Disease

with phonocardiography rule-out of CAD – fast, radiation-free, non-invasive

Basic heart facts

The basic function of the heart is to provide fresh oxygenated blood to all the organs of the body. The beating heart also needs fresh blood, as the heart muscle is constantly at work. The heart muscle is supplied via a network of smaller arteries called coronary arteries surrounding the heart muscle.

The human heart is a strong muscle of about 300 grams when fully grown. It is placed in the thorax, well protected from injury behind a cage of ribs and the sternum.

When the heart beats the resultant flow of blood through the heart create sounds described as a lub and a dub, which can be easily heard by the human ear, either directly on the chest or via a stethoscope. The lub-dub sounds are normal heart sounds associated with valves opening and closing in the heart.

A normal adult heart pumps at a frequency of about 60-70 beats per minute at rest, each time pumping out about 70 millilitres of blood. In a minute, that equals approximately the body’s blood volume, or as here, 4.900 ml of blood, also referred to as “The Cardiac Output” in millilitres per minute.

To sustain a higher cardiac output e.g. during increased activity or exercise, the heart muscle itself also needs an increased blood supply. If the heart muscle is not supplied with enough oxygenated blood because of coronary artery narrowing, most patients will typically experience some sort of chest discomfort or chest pain. This will often also be the first sign that something is not as it should be, and prompt for a visit to the physician.

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Risk factors for CAD

Medical research over recent years has shown a strong association of Coronary Artery Disease to certain risk factors, some related to our life style.

The most important risk factors are smoking, elevated blood cholesterol, obesity and high blood pressure. Being diabetic can have an additional negative impact on the risk factors.

Some studies suggest that lack of exercise and continued stress are also important factors in CAD development.

Two risk factors are unavoidable; increasing age and gender. The risk of CAD increases with age, and is higher for men than for women.

Risk factor scoring is an integrated part of evaluating a patient risk for CAD.

Diagnosis & Treatment of CAD

Symptoms of Coronary Artery Disease may be classical symptoms like chest pain or shortness of breath. Some patients however, do not experience classical symptoms, or have symptoms that are extraordinary. For this reason alone, you should consult your doctor if you suspect or experience symptoms of coronary artery disease.

The General Practitioner or Cardiologist will be able to assign a risk score for CAD, based on your symptoms, family- and medical history and the presence of one or more risk factors.

Today two scoring systems are widely used; the Framingham Score and the EU-Score, which take smoking habits, total cholesterol levels, blood pressure, age and gender into account.

If the likelihood of having CAD is sufficiently high, more examinations will often be needed for definitive diagnosis.

Typical examinations include treadmill/bicycle stress testing, and stress echo-cardiography which are both functional tests, as well as CT-scanning, which will give an image of coronary calcification, or a coronary angiography, which will show coronary artery narrowing (stenosis).

Based on the function tests or the degree of calcification or stenosis, various treatments can be offered, ranging from prescription of beta-blockers to invasive balloon dilation of stenotic arteries.

Both CT-scanning and coronary angiography are expensive procedures, requiring hospital or clinical facilities. Many patients are undergoing these procedures either as part of regular health monitoring or due to symptoms suggestive of CAD. However often they find that their symptoms are unrelated to CAD.

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Coronary Artery Disease (CAD)

Coronary Artery Disease is the result of the accumulation of fat, cholesterol and calcium into plaques on the walls of the coronary arteries that supply the heart muscle with oxygen and nutrients. The process of atherosclerosis (building up of plaque material) is largely irreversible, but can be reduced.

The degree of atherosclerosis can be determining symptoms, but as coronary artery disease evolves over a period of time the disease may go unnoticed until suddenly discovered.

One in four of all deaths by CAD is sudden and asymptomatic and thus occurs without prior warning.

Signs of plaque formation can be observed as early as in teenagers, indicating the need for a healthy life style from early childhood.

Globally, CAD is constituting more than 50% of all heart diseases, and responsible for 20 percent of all deaths.

Heart sounds for diagnosis of CAD

The heart may, however, also generate other sounds than the normal lub-dub sounds called murmurs, arising from other parts of the heart, like insufficient opening and closing of valves and from changed contraction patterns.

If the coronary arteries become narrowed, due to Coronary Artery Disease (CAD), turbulence can arise in the streaming blood, when blood is passing through the narrowing. Such turbulence murmurs may be important indicators of CAD. These murmurs cannot be heard by the human ear or a stethoscope, since they are up to 1000 times weaker than the normal heart beat sounds.

The innovative Acarix CADScor®System however, is specifically designed to undertake the delicate recording and evaluation of heart sounds that could have a CAD origin and exclude CAD acoustically

Using advanced algorithms the recorded heart sounds are analysed to identify abnormal sound patterns. The more abnormalities are identified in the heart sound recording, the higher the risk that the patient suffers from Coronary Artery Disease.

The result of the CADScor® test is categorizing patients into one of three risk groups, low, intermediate or high risk for Coronary Artery Disease.

If a patient is categorized in the low risk group, the physician can with very high reliability instantly rule-out Coronary Artery Disease, and start evaluation for other causes of discomfort, like back or shoulder pain, gastric problems or even stress related problems.

For patients categorized as intermediate or high risk patient, the physician will most likely suggest alternative next level specialist evaluation for CAD.

If the likelihood of having CAD is sufficiently high, more examinations will often be needed for definitive diagnosis.

Typical examinations include treadmill/bicycle stress testing, and stress echo-cardiography which are both functional tests, as well as CT-scanning, which will give an image of coronary calcification, or a coronary angiography, which will show coronary artery narrowing (stenosis).

Based on the function tests or the degree of calcification or stenosis, various treatments can be offered, ranging from prescription of beta-blockers to invasive balloon dilation of stenotic arteries.

Both CT-scanning and coronary angiography are expensive procedures, requiring hospital or clinical facilities. Many patients are undergoing these procedures either as part of regular health monitoring or due to symptoms suggestive of CAD. However often they find that their symptoms are unrelated to CAD.

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