Gorlin Formula Calculator
The Gorlin formula calculator follows the Gorlin equation and evaluates the aortic valve area. It provides an aortic valve area depending on the values of cardiac output, heart rate systolic ejection period, and the mean gradient. In addition, it also offers a comparison result to the aortic stenosis grading. Moreover, the Gorlin equation is also suitable for the mitral valve area and mitral stenosis grading.
This article is all about the usage and other important details of the Gorlin formula calculator. It also provides sufficient details regarding the Gorlin equation and associated factors. Stay connected with the article to clear your concepts relevant to the Gorlin formula calculator.
What are the common uses of the Gorlin formula calculator?
The Gorlin formula calculator helps to evaluate the area calculation of human cardiac valves. In common practice, it is mostly used for the calculation of the aortic and mitral valve areas. These valves play a main role to maintain the blood flow in different blood vessels. So, it is mandatory for these valves to function properly to regulate the blood flow.
What if the cardiac valve area decreases than normal?
The cardiac valve area is influential in the interpretation of any underlying diseased factor related to the valve. In diseased conditions, the cardiac valve area may decrease. Decreased valve area indicates a stenosis condition, in which the valve inlet gets narrowed. This reduced opening may cause hindrance in the normal blood flow, leading to multiple disorders.
What are the grading levels of aortic stenosis?
Aortic stenosis is one of the commonest valvular diseases caused by the narrowing or stenosis of the aortic valve. The grading level defines the severity of the aortic stenosis. Aortic stenosis may cause decreased blood flow to the aorta and other important structures of the body. In addition, the left ventricle needs to push more forcefully than normal to pass the blood through the valve because of the narrowing. The most common symptoms of aortic stenosis include
- Pain in the chest region
- Shortness of breath
- Fluttering and rapid heartbeat
- Fatigue
This condition usually occurs during the older age period due to increased chances of calcification, rheumatic fever, and scarring. In addition, younger people can also present with aortic stenosis because of a congenital bicuspid aortic valve. The aortic valve area is not the only parameter to define aortic stenosis. But, there is a grading system based on the narrowing of the aortic valve, defining the aortic stenosis severity.
| Severity level: | Aortic valve area in cm²: | Mean pressure gradient in mmHg: | Maximum aortic velocity in m/s: |
| Normal: | 3 to 4 | Lesser than 10 | Lesser than 2 |
| Mild: | 1.5 to 3 | Ranging between 10 to 19 | Ranging between 2 to 2.9 |
| Moderate: | 1 to 1.5 | Ranging between 20 to 39 | Ranging between 3 to 3.9 |
| Severe: | ≤1 | ≥40 | ≥4 |
This grading system follows the 2014 American Heart Association and American College of Cardiology guidelines. The complete guidelines explain more detailed cases following the valve anatomy and the presence of symptoms.
How can we use the Gorlin formula calculator to evaluate the aortic valve area?
The Gorlin formula calculator uses a special Gorlin equation to evaluate the aortic valve area. The Gorlin equation for aortic valve area is as follows:
Aortic valve area = cardiac output (ml/min) / [44.3 * heart rate * systolic ejection period (sec/beat) * √mean gradient]
Note: In patients with cardiac output lesser than 2.5 l/min (low flow states), the Gorlin formula equation often inclines towards more severe stenosis. In such cases, the aortic valve area is determined by using the continuity equation to get better results.
Example to calculate aortic valve area
Let us take an example to elaborate on the usage of the Gorlin formula calculator according to your ease. You only need to put the specific values mentioned in the Gorlin equation to get the results of the aortic valve area. Assuming the following values of hemodynamic parameters:
Heart rate = 77 beats per minute
Cardiac output = 4.5 l/min = 4500 ml/ min
Mean pressure gradient = 16 mmHg
Systolic ejection period = 0.23 sec/beat
Let us put these values in the equation to find out the aortic valve area for these values.
Aortic valve area = 4500 ml/min / 44.3 * 77 beats/minute * 0.23 sec/beat * √16 mmHg
Aortic valve area = 1.4 cm²
This aortic valve area indicates a moderate level of aortic stenosis
How can we use the Gorlin equation to evaluate mitral valve area?
The Gorlin equation can also be used for the evaluation of the mitral valve area. But for the mitral valve area, the Gorlin equation is a bit modified and dependent on the diastolic filling period.
Mitral valve area = cardiac output / 37.7 * heart rate * diastolic filling period * √mean gradient
This Gorlin equation for mitral valve area is quite similar to the aortic valve area equation. We can further simplify this equation by using aortic valve area.
Mitral valve area = aortic valve area / 0.85
Mitral stenosis grading
Mitral stenosis disturbs the blood flow from the left atrium to the left ventricle. It results in increased pressure on the left side of the heart, leading to lung fluid congestion. The symptoms of mitral stenosis are similar to aortic stenosis except having a difference in heart sounds. The mitral stenosis grading helps to evaluate the severity level of stenosis in the mitral valve.
| Severity level: | Mitral valve area in cm²: | Mean gradient in mmHg: | Pulmonary arterial systolic pressure in mmHg: |
| Normal: | 4 – 5 | – | 10 – 20 |
| Mild: | 1.5 – 4 | Lesser than 5 | 20 – 30 |
| Moderate: | 1 – 1.5 | 5 – 10 | 30 – 50 |
| Severe: | Lesser than 1 | Greater than 10 | Greater than 50 |
Conclusion
The Gorlin formula calculator is used for the calculation of the cardiac valve area. Most commonly, this calculator is used for the evaluation of the aortic and mitral valve areas. This Gorlin formula calculator follows the specific Gorlin equation for the aortic and mitral valve area. There are some modifications in the Gorlin equation depending on whether you are evaluating the aortic valve area or the mitral valve area. In addition, the Gorlin formula calculator also depends on multiple hemodynamic parameters, including cardiac output, heart rate, and mean pressure gradient.
Moreover, there is a limitation of the Gorlin formula calculator in case of low fluid states. In patients with low cardiac output, the Gorlin formula calculator tends to provide results regarding the severe level of aortic stenosis. In such cases, it is recommended to use the continuity equation instead of Gorlin equation for better results.
Frequently asked questions (FAQs)
What is the normal value for the aortic valve area?
The normal aortic valve area ranges between 3 to 4 cm². The aortic valve area below 3 cm² indicates aortic stenosis. Whereas, if the values decrease below 1 cm² for the aortic valve area, it indicates a severe level of aortic stenosis.
What is the main difference between aortic and mitral stenosis?
The main difference between aortic and mitral stenosis lies between heart sounds. As the left ventricle needs to push harder than normal during aortic stenosis, the murmur sound is high-pitched because of the increased pressure gradient between the left ventricle and the aorta. Whereas in the case of mitral stenosis, there is decreased pressure in the left atrium and left ventricle (but increased pressure in the lungs), the murmur sound is low-pitched during diastole.