Get acquainted with the aortic valve surface calculator to determine the areas of the patient’s aortic valve. It is also recommended to assess the severity of aortic stenosis and calculate the AVA index. In the article below, you can get information about the calculation formulas and explain the meaning of the term aortic valve.

 What is the aortic valve area?

The human heart contains an aortic valve located between the left ventricle of the heart and the aorta. This is the last part of the heart through which blood flows before entering the circulatory system. With each heart muscle contraction, blood comes out of the left ventricle and travels through the aortic valve. The moment the left ventricle of the heart contracts, the pressure rises, leading to the aortic valve opening and allowing blood to flow into the aorta and further into the body.

As part of the cardiac system, the aortic valve is susceptible to two conditions: aortic stenosis and aortic regurgitation. The notion of aortic stenosis occurs if the valve is not fully opened, which can effectively move blood in the aorta, leading to blockage. Rheumatic fever or degenerative calcification may be the cause of aortic stenosis. When it comes to the occurrence of a condition of aortic regurgitation, it occurs due to the wrong direction of the flow of oxygenated blood. Simply put, blood is regularly pumped into the aorta, but the valve does not prevent the re-entry of blood into the ventricular drug.

What is aortic stenosis?

We mentioned the concept of aortic stenosis, and now we will give a more detailed description of this condition. Aortic stenosis occurs when the opening of the aortic valve is much smaller due to the failure to open the aortic valve’s wings fully. It is presented as one of the most common and severe problems with the heart valve in medicine. If aortic stenosis occurs, the flow of blood from the ventricular to the aorta is restricted, resulting in pressure problems. The cause of this disease in people over the age of 70 is calcification of the three-winged aortic valve, better known as “senile degeneration”. For people younger than 70, the cause of aortic stenosis is the so-called bicuspid aortic valve. Another well-known disease that can also lead to aortic stenosis is a rheumatic disease. Patients who have been diagnosed with this disease, in most cases, do not experience any symptoms if they have milder forms of the condition. If the blood flow is much lower than average, the patient will experience chest pain, rapid heartbeat, shortness of breath, difficulty breathing, swollen legs, and the like.

Normal aortic valve area

When it comes to the aortic valve area, you can obtain the value by performing a planimetry procedure during cardiac measurements. Studies show that the normal surface of the valve in people with normal aortic valves is between 3 and 4 cm2, and anything less than 1 cm2 is considered a severe form of aortic stenosis.

Aortic stenosis measurements
Aortic stenosis measurements

Aortic valve area index

The aortic valve area, better known as the AVA index, is calculated by dividing the aortic valve area (AVA) by the patient’s body surface area (BSA). The accuracy of estimating aortic valve processes is much more practical using the AVA index. The method of indexing AVA with the help of the AVA index significantly improves the prevention and early informing of patients about the current state of the aortic valve and the criteria for the possible occurrence of severe stenosis. According to the World Health Organization, the average AVA index ranges between 3.0 and 4.0 cm2. In comparison, the limit values for severe stenosis are less than 1.0 cm2 for AVA and less than 0.6 cm / m2 for AVA index.

AVA index
AVA index

How to calculate aortic valve area?

There are several ways to calculate the area of the aortic stenosis valve. The most commonly used method is the one performed during echocardiography. The value obtained after estimating the aortic valve opening area is a measure to increase the severity of aortic stenosis. In this case, we will explain to you how our aortic valve area calculator works. The following values are required:

LVOT – diameter of the left ventricular outflow tract;

VTI1 – subvalvular time integral of velocity; and

VTI2 – maximum time integral of the speed via the valve

The continuity equation is used to calculate according to which the blood flow in one area should be equal to the flow in another area. The flow that exits the left ventricle is compared to the flow of the aortic valve. To calculate the area of the aortic valve, the integral of the velocity-time (VTI) is used in practice, which is one of the most accurate methods. After measuring and squaring the obtained LVOT diameter value, we multiply by 0.78540 to get the cross-sectional area. After that, it is much easier to calculate the aortic valve area in cm2 by dividing the obtained value expressed in cm3 by VTI expressed in cm. As for the way our calculator works, all you have to do is enter the data for the mentioned parts of the formula, and the calculator will display the desired values in the way we have already explained.

Aortic valve area formula

Since measuring the surface area of the aortic valve by echocardiogram can, in some cases, give inaccurate values, a formula is used to calculate the area of the aortic valve that looks like this:

Aortic \; Valve \; Area \; [cm^2] =\frac {LVOT \; diameter^2 \cdot 0,7854 \cdot LVOT \; VTI} {Aortic \; Valve \; VTI}

LVOT – left ventricular outflow tract

VTI – velocity time integral

Aortic valve area calculator (AVA calculator), a practical example

Using a classic example, we will explain how to calculate:

Let us take into account that the values of LVOT, VT1, and VT2 recorded in the patient were 2.7cm, 27cm, and 55cm, respectively. By entering the value in the calculator, the obtained value of the aortic valve surface is 2.8 cm2. If we use a calculation formula it looks like this:

AVA = \frac{\left ( LVOT^{2} \cdot 0.7854 \cdot VTI_{1} \right )}{VTI_{2}}

AVA = \frac{\left ( 2.702 \cdot 0.7854\cdot 27 \right )}{55}

AVA = \frac{57.298}{55}

AVA = 1.04 cm^{2}

According to the obtained values, we can conclude that our patient has mild aortic stenosis in the range between 1.5 and 3 cm2.

FAQ?

1. What is the effect of aortic insufficiency on the heart?

When blood leaks back into the left ventricle instead of the rest of the body, it puts pressure on the left ventricle, retaining more blood. This heart part will increase sharply, and the blood will thicken.

2. When is it necessary to undergo aortic valve surgery?

If the patient is diagnosed with chronic severe aortic regurgitation, it is recommended to undergo surgery to preserve overall ventricular function.

3. What is a mechanical valve?

The term mechanical valve is related to parts made of mechanical parts and, as such, are inactive and fit well with the body’s system. Their most common use can be manifested in the form of bile valves.

4. When are the aortic and pulmonary semilunar valves open?

There are two types of heart valves: atrioventricular valves (AV) and semilunar valves. The semilunar valves separate the ventricles from the main arteries. The aortic valve has the function of separating the left ventricle from the aorta, while the pulmonary valve has the role of separating the right ventricle from the pulmonary artery. When a ventricular contraction occurs, the ventricular pressure exceeds the pressure in the artery, which results in the opening of the semilunar valves and the pumping of blood into the main arteries. Due to the increased pressure in the aorta, the pulmonary arteries push the blood towards the ventricles to close the semilunar valve.

5. What are the limits for AVR in elderly patients?

The aortic valve replacement (AVR) process in patients older than 75 years is, according to statistical indicators, more than excellent, with acceptable operative risk. If an elderly patient requests surgery from a doctor, he must not refuse it just because of his age. Restrictions related to the conduct of this procedure are related to several factors. Patients may be denied surgery due to severe comorbidities associated with other heart diseases. They can also refer to the patient’s general condition, such as chronic lung disease or liver cirrhosis. Restrictions also apply to patients who have low levels of cardiac output, which may be evidence of heart failure or heart muscle disease. In addition to these limitations, patients may have various technical difficulties, which can be an additional problem and complicate the AVR process.

Other calculators

Body surface area measure (BSA) is used in medicine as a measure of the calculated surface area of the human body that is an indicator of metabolic mass. It is calculated with the help of basic elements of more precise weight and height. The calculation formula was first developed in 1916 by Du Bois and is still used today. Accordingly, we recommend that you visit our official website and find calculators for calculating the weist to height ratio or measuring your body shape index (ABSI).