Valves of the Heart | 3D Anatomy
by Robert Tallitsch, PhD | September 28, 2021
Blog and video explanation on the valves of the heart and heart valve surgery with symptoms, causes, treatments and a patient case example!
Written by: Robert Tallitsch, PhD
In order for the cells of the body to function they must receive nutrients and eliminate wastes — processes dependent upon the circulation of the blood. Blood flow is accomplished by the pumping actions of the heart and the proper functioning of the cardiovascular system. Blood passes through a valve before leaving each chamber of the heart, thereby preventing the backflow of blood.
The Atrioventricular Valves
The atrioventricular (AV) valves are located between the right atrium and the right ventricle (right AV valve or tricuspid valve), as well as between the left atrium and the left ventricle (left AV valve, bicuspid, or mitral valve). Each atrioventricular valve consists of four parts.
- The annulus (annulus fibrosis) of the fibrous skeleton serves as the foundation of the AV valves.
- The valve cusps are thin sheets of tissue attached to the annulus. When these cusps overlap they should completely close the opening of the AV valve.
- Thin, tough cords of connective tissue termed chordae tendineae attach to the ventricular margins of the valve cusps.
- Cone-shaped pieces of ventricular muscle, termed papillary muscles, project into the cavity of the ventricle from the ventricular wall. The pointed ends of these papillary muscles attach to the chordae tendineae of the AV valves.
The right AV valve typically has three cusps, but often exhibits only two. The left AV valve, which is the thicker of the two valves, has two cusps. The interior of the cusps contains an extension of the fibrous skeleton of the heart. A thin layer of connective tissue that is an extension of the endocardium – the lining of the heart – covers the atrial and ventricular surfaces of the valves.
The Semilunar Valves
The two semilunar valves are located in the roots of the aorta (aortic semilunar valve) and pulmonary trunk (pulmonary semilunar valve). Each semilunar valve consists of two parts: the anulus, which serves as the foundation for the valves, and three semilunar cusps, which are small, thin leaflets of connective tissue. Each cusp is half-moon in shape, with a margin attached to the annulus and a free margin extending superiorly into the lumen of the artery.
The leaflets of the semilunar valves are covered by epithelial tissue. The proximal side is covered by a continuation of the endocardium of the heart, while the distal side is covered by a continuation of the endothelium of the aorta (on the aortic semilunar valve) or pulmonary trunk (on the pulmonary semilunar valve).
Types of Heart Valve Disorders
Heart valve disorders may be congenital (present at birth) or may be acquired after birth. Some causes of acquired heart valve disorders are:
- Rheumatic fever, which is an inflammatory illness that may follow a severe streptococcal throat infection.
- Endocarditis, which is an inflammation of the heart valves.
- Connective tissue disorders, such as Marfan’s syndrome.
- Idiopathic calcified aortic stenosis, which is a degenerative condition seen with increased age. In this condition the aortic valve cusps thicken, fuse, and become infiltrated with calcium.
Although someone with a heart valve disorder may not exhibit symptoms, here are some common symptoms of a heart valve disorder:
- Heart murmur
- Constant fatigue
- Shortness of breath — especially during exercise
- Repeated dizziness and/or fainting
- Swelling of the ankles or feet
- Abdominal swelling
A heart valve may not open properly, causing valvular stenosis, or may not close properly, causing valvular prolapse (insufficiency).
Left AV valve prolapse is a common valvular disorder, particularly in females between the ages of 14- and 30-years of age. The cause for this disorder is unknown, and most females with this condition do not exhibit symptoms. AV prolapse in males is often a progressive disease, with the valve cusps deteriorating with age. This condition often requires surgical repair or replacement of the valve.
Right AV stenosis is typically the result of a severe case of rheumatic fever. In many of these cases some damage to the left AV valve is also seen.
In adults, damage to the right AV valve and/or the pulmonary valve is often the result of pulmonary hypertension (high blood pressure within the pulmonary vasculature). Pulmonary hypertension may be related to sleep apnea or COPD (chronic obstructive pulmonary disease).
Treatment of Heart Valve Disorders
The treatment of a heart valve disorder will be determined by the severity of the disease and the probability of the disease progressing and severely affecting the patient’s quality of life. Repair or replacement of a heart valve may be accomplished by several different techniques.
Treatment of valvular stenosis
- Valvotomy by traditional surgical procedures: In this procedure the surgeon performs open-heart surgery in order to separate valve cusps that have become fused together.
- Percutaneous balloon valvoplasty: Here a catheter with a balloon is inserted into an artery or vein and passed into the heart and through the affected valve. The surgeon then inflates the balloon and pulls the balloon back through the valve in an attempt to widen the valve.
Treatment for valvular prolapse
- This type of valvular disorder may be repaired by traditional open-heart surgical procedures.
Transcutaneous valve replacement
- In this type of surgery (which typically involves the aortic valve or the left AV valve) the replacement valve is crimped onto a deflated balloon, which is attached to a catheter. The catheter is inserted into the femoral or brachial artery and is maneuvered into place. The balloon is then inflated, expanding the new valve. The new valve is then surgically placed at the location of the damaged valve. Once the new valve is in place the balloon is deflated and the catheter is removed.
The maintenance of homeostasis within the tissues and fluids of the body is dependent upon the function of the cardiovascular system. The proper functioning of the cardiovascular system is, in turn, dependent upon the function of the heart. Ensuring that blood flows through the heart in the proper direction is the function of the four heart valves.
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