What is the Difference Between Mitral Valve and Aortic Valve

The main difference between mitral valve and aortic valve is that the mitral valve is located between the left atrium and the left ventricle whereas aortic valve is located between the left ventricle and the aorta. Furthermore, the mitral valve consists of two flaps while the aortic valve consists of three flaps. 

Mitral valve and aortic valve are two types of heart valves which allow the directional flow of blood through the heart. The mitral valve is also called the bicuspid valve. 

Key Areas Covered 

1. What is Mitral Valve
     – Definition, Features, Role
2. What is Aortic Valve
     – Definition, Features, Role
3. What are the Similarities Between Mitral Valve and Aortic Valve
     – Outline of Common Features
4. What is the Difference Between Mitral Valve and Aortic Valve
     – Comparison of Key Differences  

Key Terms

Aorta, Aortic Valve, Bicuspid Valve, Heart Valves, Left Atrium, Left Ventricle, Oxygenated Blood

What is Mitral Valve 

The mitral valve is the left atrioventricular (AV) valve of the heart, located between the left atrium and the left ventricle. The right atrioventricular valve is the tricuspid valve located between the right atrium and the right ventricle. The mitral valve is also called the bicuspid valve since it is made up of two flaps. It allows the unidirectional blood flow from the left atrium to the left ventricle.  

Actually, the left atrium receives oxygenated blood from the lungs through the pulmonary veins. This blood has to be transported to the aorta through the left ventricle. During the contraction or the systole of the left ventricle to supply blood to the aorta, the pressurized blood tends to enter the left atrium and the mitral valve is there to prevent that backward flow of the blood. The mitral valve is closed at this moment. When the mitral valve is closed, the left atrium fills with the oxygenated blood for the second round. Again, when the mitral valve opens, that blood can flow to the left ventricle. 

Figure 1: The Mitral Valve

The three main types of clinical problems occurring in the mitral valve are the mitral valve prolapse, which is the loosening of the muscles of the valve, mitral valve regurgitation, and mitral valve stenosis. 

What is Aortic Valve 

The aortic valve is one of the two types of semilunar (SL) valves of the heart. It is located between the left ventricle and the aorta. The other semilunar valve of the heart is the pulmonary valve located between the right ventricle and the pulmonary trunk. Generally, the semilunar valves are more similar to the valves in the veins rather than the atrioventricular valves in the heart.  

When the left ventricle contracts at the ventricle systole, the aortic valve also opens, allowing the flow of the oxygenated blood into the aorta. The aorta is the main artery of the body, which supplies oxygenated blood throughout the body. At diastole, the ventricle relaxes and due to the low pressure inside the ventricle, the blood inside the aorta tends to move back to the left ventricle. In order to prevent this, the aortic valve closes. Also, at this moment, the mitral valve opens allowing the blood flow to the left ventricle. The closed aortic valve prevents the entering of this blood to the aorta as well. This allows the heart to supply blood to the aorta with a pressure.  

Figure 2: Blood Flow through the Heart Valves

The two main types of clinical problems associated with the aortic valve are aortic regurgitation/aortic insufficiency and aortic stenosis. 

Similarities Between Mitral Valve and Aortic Valve 

• Mitral valve and aortic valve are two types of valves found in the heart. 
• They are made up of flaps, which can prevent the bidirectional blood flow. 
• The main function of these valves is to assure a unidirectional blood flow through the heart. 
• Also, both mitral and aortic valves allow the flow of oxygenated blood since they are located in the left side of the heart. 
• The general term which refers to the dysfunction of the heart valves is valvular heart disease. The two main forms of valvular heart disease are regurgitation and stenosis. The flow of blood in the wrong direction by a dysfunctional valve is called the regurgitation while stenosis refers to the narrowing of the heart valves. 

Difference Between Mitral Valve and Aortic Valve 

Definition 

Mitral valve is the valve of the heart located between the left atrium and the left ventricle while aortic valve is the valve of the heart located between the left ventricle and the aorta. Thus, this is the main difference between mitral valve and aortic valve.

Type of Valve 

Another difference between mitral valve and aortic valve is that the mitral valve is one of the two types of atrioventricular valves while the aortic valve is one of the two types of semilunar valves.  

Heart Sound 

The closure of the atrioventricular valves, including the mitral valve causes the lub or the first heart sound while the closure of the semilunar valves, including the aortic valve, causes the dub or the second heart sound. 

Flaps 

While mitral valve has two flaps, aortic valve has three flaps. Therefore, the number of flaps in each contributes to another difference between mitral valve and aortic valve.

Chordae Tendineae  

Furthermore, the mitral valve consists of chordae tendineae, which prevents the valves from inverting while the aortic valve does not contain chordae tendineae. 

Rhythm 

Also, while the mitral valve closes when the aortic valve opens, the aortic valve closes when the mitral valve opens. 

Function 

Another important difference between mitral valve and aortic valve is their function. Mitral valve supplies blood from the left atrium to the left ventricle while the aortic valve supplies blood from the left ventricle to the aorta.  

Role 

The mitral valve is responsible for preventing the backward flow of blood to the left atrium during the ventricular systole while the aortic valve is responsible for preventing the backward flow of blood to the left ventricle during the ventricular diastole. This is another major difference between mitral valve and aortic valve.

Clinical Conditions 

Besides, the main clinical condition that arises in the mitral valve is the mitral valve prolapse while the main clinical condition that arises in the aortic valve is the aortic stenosis. 

Conclusion 

The mitral valve or the bicuspid valve is a type of atrioventricular valve located between the left atrium and the left ventricle. It prevents the backward flow of blood from the left ventricle to the left atrium during the ventricular systole. On the other hand, the aortic valve is a type of semilunar valve located between the left ventricle and the aorta. It prevents the backward flow of the blood to the left ventricle during the ventricular diastole. The main difference between mitral valve and aortic valve is their role as heart valves. 

 Reference:

1. “Roles of Your Four Heart Valves.” American Heart Association, American Heart Association, Inc, 31 May 2016, Available Here

Image Courtesy:

1. “2012 Blood Flow Relaxed Ventricles” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia  
2. “Heart valves NIH” By National Heart Lung and Blood Institute (NIH) – National Heart Lung and Blood Institute (NIH) (Public Domain) via Commons Wikimedia