The clicking sound produced by a mechanical heart valve (MHV) is a common and often unexpected experience for patients and their families. This persistent noise, which can sometimes be loud enough to be heard by others, is a direct consequence of the device’s design and function. While the sound may initially cause alarm or anxiety, it is generally an expected characteristic of a properly working mechanical valve. Understanding the mechanism behind the sound, the factors that influence its volume, and when a change in the noise requires medical attention can help demystify this aspect of living with an MHV.
The Physics of the Click
The distinctive metallic “click” is produced when the rigid components of the mechanical valve close to prevent the backflow of blood. Modern mechanical heart valves are typically made from durable materials like pyrolytic carbon, which is highly biocompatible and resistant to wear. This material is used to construct the valve’s leaflets or discs that open and close with every heartbeat.
The sound itself is generated by the rapid, forceful impact of the rigid leaflets against the inner housing ring of the valve as they snap shut. This action is necessary because the valve must close completely and quickly to maintain the heart’s one-way blood flow. The most common design currently implanted is the bileaflet valve, which features two semi-circular discs attached to a rigid ring.
Because pyrolytic carbon is a dense, hard substance, the impact creates a sharp, high-frequency sound impulse. This mechanical impact sound is then transmitted through the body’s tissues, blood, and bones to the inner ear. The sound is essentially an acoustic byproduct of the valve performing its function of regulating blood flow under significant pressure.
Why the Sound Varies in Loudness
The perceived loudness of the mechanical click varies significantly from person to person and moment to moment, even among patients with the same type of valve. This variation is due to a combination of anatomical, physiological, and environmental factors. One major factor is the valve’s location within the heart, with aortic valves often perceived as louder than mitral valves. Aortic valves are situated closer to the chest wall, allowing the sound to travel through less tissue before reaching the surface.
The amount of tissue surrounding the valve also plays a role in sound transmission. Thinner individuals generally transmit the noise more easily than those with more body tissue. Changes in the heart’s activity level directly affect the sound, since a higher heart rate or increased blood pressure leads to a more forceful closing of the valve leaflets. This increased force causes a louder click, which is often noticeable during exercise or emotional stress.
An individual’s perception of the sound can also be influenced by the surrounding environment. The noise is naturally more noticeable in very quiet settings, such as at night when ambient sound levels are low. Additionally, some patients perceive the sound as two to four times louder than nearby listeners because of vibrations transmitted directly through their body’s tissues and bone structure.
When a Change in Sound Requires Attention
While a consistent clicking sound is normal, any sudden or qualitative change in the valve’s noise should prompt an immediate medical consultation. A sudden, significant muffling or a complete absence of the expected sound can be a serious warning sign. This change may indicate that a clot has formed and is restricting the movement of the valve leaflets, a condition requiring urgent intervention.
The appearance of entirely new sounds, such as a distinct high-pitched squeak, a whooshing sound, or a hiss, is also cause for concern. A new whooshing noise might suggest that blood is leaking backward through the valve, a condition known as regurgitation. Similarly, a chaotic or irregular clicking pattern, especially when accompanied by symptoms like breathlessness or dizziness, could signal a change in heart rhythm or valve function. It is important to distinguish these qualitative changes from the normal loudness fluctuations related to heart rate or body position.
Strategies for Adjusting to the Audible Valve
Adjusting to the persistent sound of a mechanical heart valve involves a combination of psychological coping and practical noise management techniques. Many patients find that the sound eventually fades into the background as their brain adapts to the constant stimulus, especially within the first year after surgery. Reframing the sound as a positive affirmation of the valve’s proper function and the continuation of life can be a helpful psychological tool.
To manage the heightened audibility at night, many people find relief by using white noise machines, fans, or earplugs to mask the sound. Noise-canceling earplugs have been shown to effectively improve sleep quality for patients with mechanical valves. Furthermore, patients can prepare themselves for social situations by having a simple, direct explanation ready for when others notice the sound.